Category Archives: Machine Learning

Machine-learning-based diagnosis of thyroid fine-needle aspiration … – Nature.com

In this study, a combination of RI image data and color Papanicolaou-stained image data improved the accuracy of MLA for diagnosing cancer using thyroid FNAB specimens. The classification results of the MLA using color Papanicolaou-stained images were highly dependent on the size of the nucleus, but those of the MLA using RI images were less dependent on nucleus size and were affected by information around the nuclear membrane. The final algorithm using data from both types of images together distinguished thyroid cell clusters from benign thyroid nodules and PTC with 100% accuracy.

MLA has shown superior diagnostic performance using images of thyroid FNAB specimens when a convolutional neural network (CNN) architecture was adopted, which is effective for image analysis7,8,12,13. Guan et al.13 studied a CNN-based MLA for classifying hematoxylineosin-stained FNAB specimens of benign thyroid nodule and PTC (TBSRTC II, V and VI). A total of 887 fragmented color images were used in this study, which were cropped from 279 images taken using a digital camera attached to a brightfield microscope. The trained algorithm exhibited 97.7% accuracy for distinguishing between 128 test images of benign and malignant nodules. Range et al.8 used MLA to classify Papanicolaou-stained FNAB specimens of broader spectrum thyroid nodules (TBSRTC IIVI). They used 916 color images obtained using a whole slide scanner. The trained MLA distinguished malignant from benign nodules with high accuracy (90.8%), comparable to that of a pathologist. Similarly, a CNN-based MLA performed well in our study, exhibiting high-accuracy patch-level classification (97.3%) and cluster-level classification (99.0%), using only color Papanicolaou-stained images.

However, given that the purpose of FNAB is to determine whether to operate on thyroid nodules, it must not only exhibit high overall accuracy, but also minimize serious misclassification, such as classification of an obvious malignancy as benign or that of an overtly benign nodule as a malignancy. In Guans study, MLA misclassified some cases that a pathologist classified as obviously benign as a malignancy. Similarly, in Ranges study, MLA misclassified some clearly benign nodules as malignant or misclassified a malignant nodule that was indicated for surgery as benign8. These issues are problematic because they can lead to an erroneous treatment plan for patients who would receive proper treatment if they underwent the current standard care. We studied nodules with relatively distinct benign or malignant characteristics (TBSRTC II, V, and VI). Our findings that RI data improved the accuracy of MLA in these nodules have important clinical significance since these indicate a potential reduction in the aforementioned serious misclassification.

Guan et al.13 suggested that the significant misclassifications of MLA for the thyroid FNAB specimens could be related to the nucleus size. In their study, the cells in false-positive cases showed large nuclei with a high mean pixel color information similar to malignant cells, but the pathologist determined that these cells had a typically benign morphology. The authors interpreted that the classification of MLA was based on the size and staining of the nucleus, but not on the shape. Furthermore, in our results, MLA based on color images showed limitations in accurately classifying benign thyroid cells with a large nucleus or malignant thyroid cells with a small nucleus because the size of the nucleus was the main feature required for classification. However, MLA classification based on the RI image was less affected by nucleus size. This suggests that RI images for can compensate for the limitations of MLA using color images for FNAB specimens whose nuclear size is not typical for benign or malignant cells.

Further results from analyses to explain the models suggest that RI-image based MLA uses the structure and shape of the nucleus for classification. In addition to the algorithm being activated mainly for large nuclei in color images, the algorithm was activated not only by large nuclei but also by nuclei with a clear structure in RI images. The certainty of the MLA classification results was proportional to the detail of the information around the nuclear membrane when based on RI images, but not when based on color images. Detailed nuclear structures, such as nuclear membrane irregularity and micronucleoli are important indicators of thyroid cancer diagnosis26. Thus, the accuracy of MLA classification can be improved when such information is incorporated.

Another potential strength of RI images is the integration of information of a wide vertical space. In a thyroid cytology specimen, cells are scattered over a wide vertical space (i.e. multiple z-plains) rather than over a plane. A single layer (z-plain) 2D image cannot address this vertical spread, and information from out-of-focus cells is likely to be lost or distorted. In contrast, in the RI image obtained through ODT, cells located in different Z-plains are in focus simultaneously. In our study, MLA based on color images showed a false positive result for some out-of-focus patches, whereas MLA based on RI image showed a true negative result for the same image patches (data not shown). However, the out-of-focus area is only a part of the color images, and the use of multiple z-plane images did not improve the accuracy of MLA when compared to the use of a single z-plane image in a previous study8. Therefore, it is unclear whether the aforementioned factor significantly affects the accuracy of MLA.

This study has certain limitations. Despite the large number of sample measurements, this study was performed in a single center and could not cover all conditions of specimens that could exist in real clinical environments. ODT provides optimal RI imaging in un-manipulated living cells27, but we obtained RI images from chromatically stained cells. Staining acted as an extrinsic noise or artifact in the RI images, which reduced the accuracy of MLA. Further study is required to determine the effect of staining on the outcomes. Finally, up to 30% of FNABs may have indeterminate cytopathology (TBSRTC III and IV). This study targeted specimen characteristic of benign or malignant thyroid nodules (TBSRTC II, V, and VI), and therefore, the currently trained algorithm cannot be directly applied to TBSRTC III and IV specimens without relevant training.

To investigate the complementary nature of RI images and color images, a 2D MIP image was generated by projecting the 3D RI image along the z-axis, thereby excluding the influence of dimensionality. Previous studies in the field of cell classification have demonstrated improved performance when using 3D RI images compared to 2D images28,29. Although our research did not incorporate 3D images due to the specific research objectives, we plan to expand our investigations in future studies by incorporating 3D RI images and other 3D imaging modalities.

In this study, we demonstrated the efficacy of multiplexing of RI with standard brightfield imaging using a single ODT platform for MLA-based classification of benign and malignant thyroid FNABs. Multiplexed ODT showed promise for the development of a more accurate classification of thyroid FNABs while reducing the inherent uncertainty and error observed in the current diagnostic standards. Thus, an ODT-based MLA may potentially contribute to an improved cost-effective and rapid point-of-care management of thyroid malignancies.

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What Is Unsupervised Machine Learning? – The Motley Fool

Artificial intelligence (AI) is an area that focuses on enabling machines and software to process information and make decisions autonomously. Machine learning, a component of AI, involves computer systems enhancing their problem-solving and comprehension of complex issues through automated techniques.

The three central machine-learning methodologies that programmers can use are supervised learning, unsupervised learning, and reinforcement learning. For in-depth information on supervised machine learning and reinforcement machine learning, kindly refer to the articles dedicated to them. Here you can read up on the basics of unsupervised machine learning.

Image source: Getty Images.

With unsupervised machine learning, a system is like a curious toddler exploring a world they know nothing about. The system is exploring data without knowing what it's looking for but is excited -- in a digital kind of way -- about any new pattern it stumbles upon.

With this type of machine learning, algorithms sift through heaps of unstructured data without any specific directions or end goals in mind. They are looking for previously unknown patterns, much as you might look for a new stock pick in an overlooked corner of the market. This is rarely the last step since the owner of the raw data typically applies more sophisticated deep learning or supervised machine learning analyses to any potentially interesting patterns.

Why should you care about this artificial intelligence toddler on a quest without a firm goal? Well, unsupervised machine learning is actually on the cutting edge of technology and innovation. Its a key player in everything from autonomous vehicles learning to navigate roads to recommendation algorithms on your favorite streaming platforms. This pattern-finding method is a powerful first step in a deep analysis of any complex topic, from weather forecasting to genetic research.

Two major types of unsupervised learning are clustering and association.

So now you know what unsupervised machine learning is and why it matters. How can you take this newfound knowledge and put it to good use?

First off, you can make informed investment decisions. Companies leveraging unsupervised learning are often poised for growth as this technology continues to evolve. Think about Amazon (AMZN -1.27%) using unsupervised learning for its product recommendations or Netflix (NFLX -2.99%) running unsupervised machine learning routines across years of collected viewership data to generate your streaming home page and make future content production decisions.

These applications aren't just fun toys -- they are business advantages and growth drivers.

Also, AI and machine learning continue to reshape many industries. Whether you're into FAANG stocks or emerging AI startups, knowledge about unsupervised learning can give you an edge in evaluating a company's tech prowess and potential for future success.

We all appreciate a bit of connection, right? Well, thanks to unsupervised machine learning, we're getting better at finding people we might know or like on social media platforms. Facebook is a prime example.

Have you ever wondered how Facebook seems to know who your actual friends from high school are -- the ones you may actually want to keep in touch with? It's not sorcery. It's unsupervised learning in action.

Meta Platforms' (META -0.29%) massive social network continually analyzes a trove of user data, looking for patterns and shared features among users. Common friends are a helpful clue; similar locations and shared interests can point the platform in the right direction, and mutual workplaces can be the clincher. None of these qualities is enough in itself to find that long-lost flame or forgotten friend, but they add up through the power of unsupervised machine-learning algorithms.

So when Facebook suggests "People You May Know," it essentially gives you the output of an unsupervised learning model. The social network isn't just pulling these suggestions out of a digital hat. Each one is the result of a complex analysis of patterns and connections.

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What Is Unsupervised Machine Learning? - The Motley Fool

Mentorship and machine learning: Graduating student Irene Fang is … – University of Toronto

Majoring in human biology and immunology, Irene Fang capitalized on opportunities inside and outside the classroom to research innovative methods in ultrasound detection driven by artificial intelligence and machine learning. Shes also working on research into cells and proteins in humans that could lead to new treatments and therapies for immunocompromised patients.

As she earned her honours bachelor of science degree, Fang always wanted to help others succeed. As a senior academic peer advisor with Trinity College, shes admired throughout the community for her brilliance, kindness and dedication to U of T.

I want to keep giving back because I am so appreciative of the upper-year mentors I connected with, starting in first year, says Fang. They continue to serve as an inspiration, motivating me to further develop professional and personal skills.

Why was U of T the right place for you to earn your undergraduate degree?

U of T provided a plethora of academic, research and experiential learning opportunities alongside a world-class faculty to help cultivate my curiosity and consolidate my knowledge. In conjunction with an unparalleled classroom experience, I gained a real-world perspective with international considerations through the Research Opportunities Program.

I would be remiss if I didnt also mention how extracurricular activities enhanced and enriched my university experience. The many clubs at U of T helped me focus on my passions and make meaningful connections with like-minded peers who became my support network, enabling me to reach my full potential.

How do you explain your studies to people outside your field?

Im interested in machine learning, which is an offshoot of artificial intelligence that teaches and trains machines to perform specific tasks and identify patterns through programming.

There are two types of machine learning. Supervised learning involves training your machine learning algorithm with labelled images. In unsupervised learning, your algorithm learns with unlabeled images; this is advantageous as it eliminates the need to look for expert annotators or sonographers to label the images, saving time and costs. My research project compared how well unsupervised learning was able to identify and classify the three distinct ultrasound scanning planes at the human knee with supervised learning, the current standard for machine learning in ultrasound images.

My research project in immunology seeks to explore how a particular protein or receptor expressed on a specific subpopulation of human memory B cells mediates their immune responses. This is significant as memory B cells generate and maintain immunological memory, eliciting a more rapid and robust immune response upon the re-exposure to the same foreign invader, such as a pathogen or toxin, enabling a more effective clearance of the infection.

How is your area of study going to improve the life of the average person?

It is absolutely fascinating that AI has already revolutionized the medical field. Specifically, AI possesses the potential to aid in the classification of ultrasound images, enhancing early detection and diagnosis of internal bleeding because of injuries or hemophilia. Overall, AI may lead to more efficient care for patients, thereby improving health outcomes.

In terms of my immunology research, since the memory B cells expressing the specific receptor are dysregulated in people suffering from some autoimmune disorders and infectious diseases, a better understanding of how memory B cells are regulated could provide valuable insight into the underlying mechanisms of such diseases so we can enable scientists to develop new therapies that alleviate patients symptoms.

What career or job will you pursue after graduation?

I aspire to pursue a career in the medical field, conduct more research and nurture my profound enthusiasm for science while interacting with a diverse group of people. I hope to devote my career to improving human health outcomes while engaging in knowledge translation to make science more accessible to everyone.

You spent time at U of T as an academic peer advisor. Why was this work so important to you and what made it so fulfilling?

I remember feeling overwhelmed as a first-year student until I reached out to my academic peer advisors. Had I not chatted with them, I would not have known about, let alone applied for, my first research program. Looking back, it opened the door to many more new, incredible possibilities and opportunities. This experience made me realize the significance and power of mentorship, inspiring me to become an academic peer advisor. Seeing my mentees thrive and achieve their goals has made this role so rewarding so much so that I am determined to engage in mentorship throughout my career after graduation.

What advice do you have for current and incoming students to get the most out of their U of T experience?

Ask all questions because there are no silly questions. Get involved, whether it be volunteering, partaking in work-study programs, sports or joining a club. Meeting new people and talking to strangers can be daunting, but the undergraduate career is a journey of exploration, learning and growth.

Be open-minded and dont be afraid to try something new. Immersing yourself in distinct fields enables you to discover your interests and passions, which can lead you to an unexpected but meaningful path.

Also, be kind to yourself because failures are a normal part of the learning process; whats important is that you take it as an opportunity to learn, grow and bolster your resilience. And finally, although academia and work can keep you busy, remember to allocate time for self-care. Exercise, sleep and pursue hobbies because mental health is integral for success in life.

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Mentorship and machine learning: Graduating student Irene Fang is ... - University of Toronto

A reinforcement learning approach to airfoil shape optimization … – Nature.com

In the following section, we present the learning capabilities of the DRL agent with respect to optimizing an airfoil shape, trained in our custom RL environment. Different objectives for the DRL agent were tested, gathered into three tasks. In Task 1, the environment is initialized with a symmetric NACA0012 airfoil and successive tests were performed in which the agent must (i) maximize the lift-to-drag ratio L/D, (ii) maximize the lift coefficient Cl, (iii) maximize endurance (C^{3/2}_{l}/C_{d}), and (iv) minimize the drag coefficient Cd. In Task 2, the environment is initialized with a high performing airfoil having high lift-to-drag ratio and the agent must maximize this ratio. The goal is to test if the learning process is sensitive to the initial state of the environment and if higher performing airfoils can potentially be produced by the agent. In Task 3, the environment is initialized with this same higher performing airfoil, but has been flipped along the y axis. Under this scenario, we investigate the impact of initializing the environment with a poor performing airfoil on the agent and determine if the agent is able to modify the airfoil shape to recoup a high lift-to-drag ratio. Overall, these tasks demonstrate the learning capabilities of the DRL agent to meet specified aerodynamic objectives.

Since we are interested in evaluating the drag of the agent-produced airfoils, the viscous mode of Xfoil is used. In viscous flow conditions, Xfoil only requires the user to specify a Reynolds number (Re) and an airfoil angle of attack (alpha). In all tasks, the flow conditions specified in Xfoil were kept constant. A zero-degree angle of attack and Reynolds number equal to 106 were selected to define the design point for the flow conditions. The decision to keep the airfoils angle of attack at a fixed position is motivated by the interpretability of the agents policy. A less constrained problem, in which the agent can modify the angle of attack, would significantly increase the design space, leading to less interpretability of the agents actions. Additionally, the angle of attack is chosen to be fixed at zero in order to easily compare the performance of agent-generated shapes with those found in the literature. The Reynolds number was chosen to represent an airfoil shape optimization problem at speeds under the transonic flow regime15. Hence, given the relatively low Re number chosen, the flow is incompressible over the airfoil, although Xfoil does include some compressibility corrections when approaching transonic regimes (Karman-Tsien compressibility correction,43). All airfoils are thus compared at zero angle of attack.

Two parameters relating to the PPO algorithm in Stable Baselines can be set, namely the discount factor (gamma) and the learning rate. The discount factor impacts how important future rewards are to the current state: (gamma = 0) will favor short-term reward whereas (gamma = 1) aims at maximizing the cumulative reward in the long run. The learning rate controls the amount of change brought to the model: it is a hyperparameter tuning the PPO neural network. For the PPO agent, the learning rate must be withing ([5times 10^{-6}, 0.003]). A study of the effects of the discount factor and learning rate on the learning process was conducted. This study shows that optimal results are found when using a discount factor (gamma = 0.99) and learning rate equal to 0.00025.

In building our custom environment, we have set some parameters to limit the generation of unrealistic shapes by the agent. These parameters help take into account structural considerations as well as limit the size of the action space. For instance, we define limits to the thickness of the produced shape. If the generated shape (resulting from the splines represented by the control points) exhibits a thickness over or under a specified limit value, the agent will receive a poor reward. Regarding the action space, we set bounds for the change in thickness and camber. This allows the agent to search in a restricted action space thus eliminating a great number of unconverged shapes resulting from actions bringing changes to the airfoil shape that are too extreme. These parameters are given in Table2. Moreover, the iterations parameter is the number of times Xfoil is allowed to rerun a calculation for a given airfoil in the event the solver does not converge. Having a high iterations number increases the convergence rate of Xfoil but also increases run times.

The environment is initialized with a symmetric airfoil having (L/D = 0), (C_{l} = 0) and (C_{d} = 0.0054) at (alpha = 0) and (Re = 10^{6}). In a first experiment, the agent is tasked with producing the highest lift-to-drag airfoil, starting from the symmetric airfoil. During each experiment, the agent is trained over a total number of iterations (defined as the total timestep parameter), which are broken down into episodes having a given length (defined as the episode length parameter). The DRL agent is updated (i.e., changes are brought to the neural network parameters) every N steps. At the end of an experiment, several results are produced. Figure7a displays the L/D of the airfoil successively modified by the agent at the end of each episode.

Learning curves for max L/D objective starting with a symmetric airfoil.

In Fig.7a, each dot represents the L/D value of the shape at the end of an episode and the blue line represents the L/D running average value over 40 successive episodes. The maximum L/D obtained over all episodes is also displayed. Settings regarding the total number of iterations, episode length and N steps for the experiment are given above the graph. It can be observed from Fig.7a that starting with a low L/D during early episodes, the L/D at the end of an episode increases with the number of episodes. Though significant variance in the L/D at the end of an episode can be seen, with values ranging between (L/D = -30) and (L/D = 138), the average value however increases and stabilizes around (L/D = 100). This increase in L/D suggests that the agent in able to learn the appropriate modifications to bring to the symmetric airfoil resulting in an airfoil having high lift-to-drag ratio. We are also interested in tracking a score over a whole episode. Here, we arbitrarily define this score as the sum of the L/D of each shape produced during an episode. For instance, if an episode is comprised of 20 iterations, the agent will have the opportunity to modify the shape 20 times thus resulting in 20 L/D values. Summing these values corresponds to the score over one episode. If the agent produces a shape that does not converge in the aerodynamic solver, a value of 0 is added to the score, thus penalizing the score over the episode if the agent produces highly unrealistic shapes. The evolution of the score with the number of episodes played is displayed in Fig.7b.

Figure7b shows the significant increase in the average score at end of episode, signaling that the agent is learning the optimal shape modifications. We can then visualize the best produced shape over the training phase in Fig.8.

Agent-produced airfoil shape having highest L/D over training.

In Fig.8, the red dots are the control points accessible to the agent. The blue curve describing the shape is the spline resulting from these control points. It is interesting to observe that the optimal shape produced shares the characteristics of high lift-to-drag ratio airfoils, such as those found on gliders, having high camber and a drooped trailing edge. Finally, we run the trained agent on the environment over one episode and observe the generated shapes in Fig.9. Starting from the symmetric airfoil, we can notice the clear set of actions taken by the agent to modify the shape to increase L/D. The experiment detailed above was repeated by varying total timesteps, episode lengths and N steps.

Trained agent modifies shape to produce high L/D.

We then proceed to train the agent under different objectives: maximize Cl, maximize endurance and minimize Cd. Associated learning curves and modified shapes can be found in Figures10, 11, 12, 13.

Learning curves for max Cl objective starting with a symmetric airfoil.

Learning curves for max (C^{3/2}_{l}/C_{d}) objective starting with a symmetric airfoil.

For the minimization of Cd objective, the environment is initialized with a symmetric airfoil having Cd = 0.0341. This change in initial airfoil, compared to the previously used NACA0012 is justified by enhanced learning visualizations.

Learning curves for min Cd objective starting with a symmetric airfoil.

Trained agent modifies shape to produce low Cd starting with a low-performance airfoil.

Similarly, the results show a clear learning curve during which both the metric of interest and the score at end of episode increase with the number of episodes. The learning process appears to happen within the first 100 episodes as signaled by the rapid increase in the score and then plateaus, oscillating around an average score value.

A second set of experiments was performed to assess the impact of the initial shape. The environment is initialized with a high performing airfoil (i.e., having a relatively high lift-to-drag ratio) and the agent is tasked with bringing further improvement to this airfoil. We chose this airfoil by investigating the UIUC database41 and selected the airfoil having the highest L/D. This corresponds to the Eppler 58 airfoil (e58-il) having (L/D = 160) at (alpha = 0) and (Re = 10^{6}), displayed in Fig.14. Results for this experiments are displayed in Fig.15.

Eppler 58 high lift-to-drag ratio airfoil.

Learning curves for max L/D objective starting with a high L/D airfoil.

It is interesting to compare the learning curves and average scores achieved when starting with the symmetric airfoil and the high performance airfoil.

In Fig.16, we can observe that for both initial situations there is an increase in the average score during early episodes followed by stagnation, demonstrating the learning capabilities of the agent. However, the plateaued average score reached is significantly higher when the environment is initialized with the high performance airfoil, given that the environment is initialized in an already high-reward region (through the high-performance airfoil). Additionally, it was observed that a slightly higher maximum L/D value could be achieved when starting with the high lift-to-drag ratio airfoil. Overall, Task 1 and Task 2 emphasize the robustness of the RL agent to successfully converge on high L/D airfoils, regardless of the initial shapes (in both experiments, the agent converges on airfoils having (L/D > 160)). The agent-generated airfoil for Task 2 is represented in Fig.21a.

Initial airfoil impact on the learning curve.

For Task 3, the starting airfoil is a version of the Eppler 58 airfoil that has been flipped around the y axis. As such, the starting airfoil has a lift-to-drag ratio opposite of the Eppler 58 (i.e., (L/D = -160)), thus exhibits low aerodynamic performance. The goal for this task is for the agent to modify the shape into a high performing airfoil, having high L/D.

In Fig.17, we display the learning curves associated to the score and L/D value at the end of each episode when the environment is initialized with the flipped e58 airfoil at the beginning of each episode. A noticeable increase in both the score and L/D values between episode 30 and episode 75 can be observed, followed by a plateau region. This demonstrates that the agent is able to learn the optimal policy to transform the poor performing airfoil into a high performing airfoil by bringing adequate changes to the airfoil shape. The agent then applies this learned optimal policy after episode 100. Moreover, the agent is capable of producing airfoils having lift-to-drag ratios equivalent or higher than the Eppler e58 high-performance airfoil, signaling that the initial airfoil observed by the agent does not impact the optimal policy learned by the agent, but rather only delays its discovery (see Figs.15 and 17).

Score and L/D learning curves when starting with a low performance airfoil.

An example of a high L/D shape produced by the DRL agent when starting with the flipped e58 airfoil is displayed in Fig.18. It is interesting to notice that in this situation, the produced airfoil shares previously observed geometric characteristics, such as high camber and a drooped trailing edge, leading to a high L/D value. The trained agent is then run over one episode length in Fig.19. By successively modifying the airfoil shape, we can observe that the agent is able to recover positive L/D values having started with a low performance airfoil. This demonstrate the correctness of the behavior learned by the agent.

Agent-produced airfoil shape when starting with low performance airfoil.

Trained agent modifies shape to produce high L/D starting with a low-performance airfoil.

Finally, the best produced shapes (i.e., those maximizing the metric of interest) for the different objectives and tasks can now be compared, as illustrated in Figs.20 and21.

Best performing agent-produced shapes under different objectives and a symmetric initial airfoil.

Best performing agent-produced shapes under different objectives and an asymmetric initial airfoil.

The results presented above demonstrate that the number of function evaluations (i.e., the number of times Xfoil is run and converges on a new shape proposed by the agent) depends on the task at hand. For instance, around 2,000 function evaluations were needed in Task 2, while 4,000 are needed in Task 1 and around 20,000 were required in Task 3. These differences can be explained by the distance that exists between the starting shape and the optimal shape. In other terms, when starting with the low performing airfoil, the agent has to perform a greater number of successful steps to converge on an optimal shape, whereas when starting with an already high-performance airfoil, the agent is close to an optimal shape and requires fewer Xfoil evaluations to converge on an optimal shape. The number of episodes needed to reach an optimal policy, however, appears to be between 100 and 200 episodes across all tasks. Overall, when averaging across all tasks performed in this research, approximately 10,000 function evaluations were needed for the agent to converge on the optimal policy.

Having trained the RL agent on a given aerodynamic task, the designer can then draw physical insight by observing the actions the agent follows to optimize the airfoil shape. From the results presented in this research, it can be observed that high camber around the leading edge and low thickness around the trailing edge are preferred shapes to maximize L/D, given the flow conditions used here. Observing the various policies corresponding to different aerodynamic tasks, the designer can then make tradeoffs between the different aerodynamic metrics to optimize. Multi-point optimization can be achieved by including in the reward multiple aerodynamic objectives. For example, if the designer seeks to optimize both L/D and Cl, a new definition of the reward could be: (r = (L/D_{current} + Cl_{current})-(L/D_{previous} + Cl_{previous})) (after having normalized L/D and Cl). However, multi-point optimization will decrease interpretability of the agents actions. By introducing multiple objectives in the agents reward, it will become more difficult for the designer to draw insight from shape changes and link those changes to maximizing a specific aerodynamic objective.

The proposed methodology enables to reduce computational costs by leveraging a data-driven approach. Having learned an optimal policy for a given aerodynamic objective, the agent can be used to optimize new shapes, without having to restart the whole optimization process. More specifically, this approach can be used to alleviate the computational burden of problems requiring high-fidelity solvers (when RANS or compressibility are required). For these problems, the DRL agent can quickly find a first optimal solution, using a low-fidelity solver. The solution can then be refined using a higher-fidelity solver and a traditional optimizer. In other words, DRL is used in this context to extract prior experience to speed up the high-fidelity optimization. As such, our approach can speed up the airfoil optimization process by very rapidly offering an initial optimal solution. Similarly to8, our approach can also be used directly for high-fidelity models. To accelerate convergence speeds, the DRL agent is first trained using a low-fidelity solver in order to rapidly learn an optimal policy. The agent is then deployed using a high-fidelity solver. In doing so this approach (i) reduces computational cost by shifting from a low to a high-fidelity solver to speed up the learning process, (ii) is data-efficient as the policy learned by the agent can then be followed for any comparable problem and, (iii) bears some generative capabilities as it does not require any user-provided data.

As reinforcement learning does not rely on any provided database, no preconception of what a good airfoil shape should look like is available to the agent. This results in added design freedom leading the agent to occasionally generate airfoil shapes that can be viewed as unusual to the aerodynamicists eye. In Fig.22, we compare agent-produced shapes to existing airfoils in literature. The focus is not on the agents ability to produce a specific shape for given flow conditions and aerodynamic targets, but rather to illustrate the geometric similarities found on both existing airfoils and artificially-generated shapes. A strong resemblance between the agent-generated and existing airfoils can be observed. This highlights the rationality of the policy learned by the agent: having no preexisting knowledge on fluid mechanics or airfoils, an intelligent agent trained in the presented custom RL environment can generate realistic airfoil shapes.

We compare five existing airfoils to our agent-produced shapes in Fig.22. In Fig.22a and b, we compare the agent-produced shape to Whitcombs supercritical airfoil. The shared flat upper surface, cambered rear and blunt trailing edge can be noticed51. We then compare agent-generated shapes to existing high-lift airfoils. Here also, the geometric resemblance is noticeable, notably the shared high camber.

Airfoil shape comparison between agent-produced shapes and existing airfoils.

Detrimental effects of large episode lengths.

One observation was made when noticing drastic decreases in the average score at the end of episode after a first period of increase. We believe this can be explained by the fact that when the episode length is large, once the agent has learned a policy allowing to quickly (under relatively few iterations) attain high L/D values, the average score will then decrease because the agent reaches the optimal shape before the end of the episode. Within the remaining iterations before the episode ends, the agent continues to modify the shape hoping for higher performance, but reaches a limit where the shape is too extreme for the aerodynamic solver to converge, resulting in a poor reward. This would explain why we can observe on Fig.23 a rapid increase in the score between 0 and 25 episodes, during which the agent explores various shapes and estimates an optimal policy, and a strong decrease in the score following this peak during which the agent follows the determined optimal policy and reaches optimal shapes before the episode ends.

The results presented above demonstrate the ability of a DRL agent to learn how to optimize airfoil shapes, provided a custom RL environment to interact with. We now compare this approach to a classical simplex method, under the same possible action conditions: starting from a symmetric airfoil, the optimizer must successively modify the shape by changing thickness and camber at selected x positions to achieve the highest performing airfoil in terms of L/D.

Here, the optimizer is based on the Nelder-Mead simplex algorithm, capable of finding the minimum of a multivariate function without having to calculate the first or second derivatives52. In this case, the function maps a 3-set of actions, being [select x position, change thickness, change camber] to a -L/D value. More specifically, taking the 3-set of actions as inputs, the function modifies the airfoil accordingly, evaluates the modified airfoil in Xfoil and outputs the associated -L/D. As the optimizer tries to minimize the- -L/D value, it searches for the 3-set that will maximize L/D. Once the optimizer finds the optimal 3-set of actions, the airfoil shape is modified accordingly and the optimizer is rerun on this new modified shape. This defines what we call one optimization cycle. Hence, the optimizer is tasked with the exact same optimization problem as the DRL agent: optimizing the airfoil shape to reach the highest L/D value possible by successively modifying the shape. During each optimization cycle, the optimizer evaluates the function a certain number of times. In Fig.24, we monitor the increase in L/D with the number of function evaluations.

Simplex method approachL/D increase with function evaluations for different starting points.

In the three situations displayed, it can be observed that the value of L/D increases with the number of function evaluations. However, the converged L/D value is significantly lower than values obtained through the DRL approach. For instance, even after 500 optimization cycles (i.e., 500 shape modifications and over 30,000 function evaluations), the optimizer is unable to generate an airfoil having L/D over 70. We know that this value of L/D is not a global optimum, as an L/D of at least 160 can be reached with the Eppler 58 airfoil from the UIUC database41. Thus, it seems that the simplex algorithm has converged on a local minimum. Furthermore, as demonstrated in Fig.24a and c, the converged L/D value found by the optimizer is highly dependent on the initial point. The airfoil shapes generated using the simplex method can be found in Fig.25.

Gradient-free approach generated airfoil shapes.

In Table3, we compare the converged L/D values, number of iterations and run times of the simplex method and DRL approach. In both approaches, the agent or optimizer can modify the airfoil 60 times. Although the number of iterations and run time are lower for the simplex method, the converged L/D value is far lower compared to the DRL approach.

This rapid simplex approach to the airfoil shape optimization problem highlights the benefits and capabilities of the presented DRL approach. First, the DRL approach seems less prone to convergence on local minima, as very high values of L/D can be achieved. Second, once the DRL agent has learned the optimal policy during a training period, it can be applied directly to any new situation whereas the simplex approach will require a whole optimization process for each new scenario encountered.

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Breaking the 21-Day Myth: Machine Learning Unlocks the Secrets of … – SciTechDaily

A machine learning-based study by Caltech reveals that habit formation varies greatly, with gym habits taking six months to establish on average, while healthcare workers form a hand-washing habit in a few weeks. The study emphasized the power of machine learning in researching human behavior outside lab conditions.

New machine learning study finds different habits take varying amounts of time to take root.

Putting on your workout clothes and getting to the gym can feel like a slog at first. Eventually, you might get in the habit of going to the gym and readily pop over to your Zumba class or for a run on the treadmill. A new study from social scientists at Caltech now shows how long it takes to form the gym habit: an average of about six months.

The same study also looked at how long it takes healthcare workers to get in the habit of washing their hands: an average of a few weeks.

There is no magic number for habit formation, says Anastasia Buyalskaya (PhD 21), now an assistant professor of marketing atHEC Paris. Other authors of the study, which appears in the journalProceedings of the National Academy of Sciences,include CaltechsColin Camerer, Robert Kirby Professor of Behavioral Economics and director and leadership chair of the T&C Chen Center for Social and Decision Neuroscience, and researchers from the University of Chicago and the University of Pennsylvania. Xiaomin Li (MS 17, PhD 21), formerly a graduate student and postdoctoral scholar at Caltech, is also an author.

You may have heard that it takes about 21 days to form a habit, but that estimate was not based on any science, Camerer says. Our works supports the idea that the speed of habit formation differs according to the behavior in question and a variety of other factors.

The study is the first to use machine learning tools to study habit formation. The researchers employed machine learning to analyze large data sets of tens of thousands of people who were either swiping their badges to enter their gym or washing their hands during hospital shifts. For the gym research, the researchers partnered with 24 Hour Fitness, and for the hand-washing research, they partnered with a company that used radio frequency identification (RFID) technology to monitor hand-washing in hospitals. The data sets tracked more than 30,000 gymgoers over four years and more than 3,000 hospital workers over nearly 100 shifts.

With machine learning, we can observe hundreds of context variables that may be predictive of behavioral execution, explains Buyalskaya. You dont necessarily have to start with a hypothesis about a specific variable, as the machine learning does the work for us to find the relevant ones.

Machine learning also let the researchers study people over time in their natural environments; most previous studies were limited to participants filling out surveys.

The study found that certain variables had no effect on gym habit formation, such as time of day. Other factors, such as ones past behavior, did come into play. For instance, for 76 percent of gymgoers, the amount of time that had passed since a previous gym visit was an important predicator of whether the person would go again. In other words, the longer it had been since a gymgoer last went to the gym, the less likely they were to make a habit of it. Sixty-nine percent of the gymgoers were more likely to go to the gym on the same days of the week, with Monday and Tuesday being the most well-attended.

For the hand-washing part of the study, the researchers looked at data from healthcare workers who were given new requirements to wear RFID badges that recorded their hand-washing activity. It is possible that some health workers already had the habit prior to us observing them, however, we treat the introduction of the RFID technology as a shock and assume that they may need to rebuild their habit from the moment they use the technology, Buyalskaya says.

Overall, we are seeing that machine learning is a powerful tool to study human habits outside the lab, Buyalskaya says.

Reference: What can machine learning teach us about habit formation? Evidence from exercise and hygiene by Anastasia Buyalskaya, Hung Ho, Katherine L. Milkman, Xiaomin Li, Angela L. Duckworth and Colin Camerer, 17 April 2023, Proceedings of the National Academy of Sciences.DOI: 10.1073/pnas.2216115120

The study was funded by the Behavior Change for Good Initiative, the Ronald and Maxine Linde Institute of Economics and Management Sciencesat Caltech, and theTianqiao and Chrissy Chen Institute for Neuroscienceat Caltech.

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Zero-Shot Learning Demystified: Unveiling the Future of AI in … – YourStory

Machine learning has made significant strides in recent years, demonstrating remarkable capabilities in various domains such as image recognition, natural language processing, and recommendation systems. However, a fundamental limitation of traditional machine learning approaches is their reliance on labeled training data. This requirement poses a challenge when confronted with new, unseen classes or categories. Zero-Shot Learning (ZSL) emerges as a powerful technique that addresses this limitation, enabling machines to learn and generalise from previously unseen data with astonishing accuracy.

Zero-Shot Learning is an approach within machine learning that enables models to recognise and classify new instances without explicit training on those specific instances. In other words, it empowers machines to understand and identify objects or concepts they have never encountered before. Traditional machine learning models heavily rely on labeled training data, where each class or category is explicitly defined and represented. However, in real-world scenarios, it is impractical and time-consuming to label every possible class.

ZSL leverages the power of semantic relationships and attribute-based representations to bridge the gap between seen and unseen classes. Instead of relying solely on labeled training examples, ZSL incorporates additional information such as textual descriptions, attributes, or class hierarchies to learn a more generalised representation of the data. This allows the model to make accurate predictions even for novel or previously unseen classes.

Zero-Shot Learning operates on the premise of transferring knowledge learned from seen classes to unseen ones. The process typically involves the following steps:

Dataset Preparation: A dataset is created, containing labeled examples of seen classes and auxiliary information describing the unseen classes. This auxiliary information could be textual descriptions, attribute vectors, or semantic embeddings.

Feature Extraction: The model extracts meaningful features from the labeled data, learning to associate visual or textual representations with class labels. This step is crucial in building a robust and discriminative representation of the data.

Semantic Embedding: The auxiliary information for unseen classes is mapped into a common semantic space. This step enables the model to compare and relate the features of seen and unseen classes, even without explicit training examples.

Knowledge Transfer: The model leverages the learned features and semantic relationships to make predictions on unseen classes. By understanding the shared attributes or semantic characteristics, the model can generalise its knowledge to recognise and classify previously unseen instances accurately.

Zero-Shot Learning offers several advantages and opens up new possibilities in the field of machine learning:

Scalability: ZSL eliminates the need for retraining models every time a new class is introduced. This makes the learning process more efficient and scalable, as the model can seamlessly adapt to novel categories without requiring additional labeled examples.

Flexibility: ZSL allows for the incorporation of diverse sources of information, such as textual descriptions or attribute vectors, enabling models to generalise across different modalities. This flexibility broadens the applicability of machine learning in domains where explicit training data may be scarce or costly to obtain.

Real-World Relevance: In many real-world scenarios, new classes continuously emerge or evolve. Zero-Shot Learning equips models with the ability to adapt and recognise novel instances, making them more applicable in dynamic environments where traditional models would struggle.

Transfer Learning: ZSL leverages the knowledge gained from seen classes to make predictions on unseen classes. This ability to transfer knowledge opens up possibilities for transferring models trained on one domain to another related domain, even if the new domain lacks labeled examples.

The applications of Zero-Shot Learning are far-reaching and have the potential to transform various industries. Some notable applications include:

Object recognition and image classification in domains where new classes emerge frequently, such as wildlife conservation or fashion industry.

Natural language processing tasks like text categorisation or sentiment analysis, where new topics or categories continuously emerge.

Recommendation systems, where ZSL can enable personalised recommendations for previously unseen items or niche categories.

While Zero-Shot Learning has shown remarkable promise, there are still challenges that researchers and practitioners aim to address. Some of the key areas of focus include:

Semantic Gap: Bridging the semantic gap between seen and unseen classes remains a challenge. Developing more accurate and robust methods for mapping semantic information to feature representations is essential for improving ZSL performance.

Fine-Grained Learning: Zero-Shot Learning is particularly challenging in fine-grained domains where subtle differences exist between similar classes. Developing techniques that can capture and discriminate these fine-grained details is an ongoing research area.

Data Bias: Ensuring the fairness and generalisation of Zero-Shot Learning models is crucial. Models must be designed to handle data biases and prevent biased predictions when dealing with unseen classes.

As research continues in these areas, Zero-Shot Learning will likely continue to evolve, pushing the boundaries of machine learning and enabling machines to learn and generalise from previously unseen data in even more sophisticated ways.

Zero-Shot Learning represents a significant advancement in the field of machine learning by overcoming the limitations of traditional approaches. By leveraging auxiliary information and semantic relationships, ZSL enables machines to recognize and classify novel classes accurately, without the need for explicit training examples. With its scalability, flexibility, and real-world relevance, Zero-Shot Learning opens up new opportunities for applications in various domains. As research progresses and the challenges are addressed, ZSL is set to revolutionise the way machines learn and adapt, paving the way for more intelligent and capable systems

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Striking a Balance: The Imperative of Regulating Machine Learning – BBN Times

Machine learning, a branch of artificial intelligence (AI), has experienced significant advancements in recent years.

It has transformed industries, revolutionized decision-making processes, and powered innovations that were once deemed unimaginable. However, the rapid proliferation of machine learning technologies has raised concerns regarding their potential societal impact. As machine learning algorithms become increasingly autonomous and influential, the need for regulatory frameworks to govern their deployment and mitigate potential risks has become crucial. This article delves into the pressing need for regulating machine learning and explores the challenges, benefits, and potential approaches to ensure the responsible and ethical use of this powerful technology.

Machine learning algorithms are designed to analyze vast amounts of data, detect patterns, and make predictions or decisions based on learned patterns. These algorithms can autonomously improve their performance through iterative learning processes, without being explicitly programmed for every task. As a result, they have found applications in various domains, including finance, healthcare, transportation, and entertainment, among others.

While the advancements in machine learning bring numerous benefits, they also present challenges and risks that demand regulatory attention. Some of the key concerns include:

Machine learning algorithms learn from historical data, which can perpetuate biases present in the data. This can lead to discriminatory outcomes, such as biased hiring practices or unfair lending decisions. Without proper regulation, these biases can reinforce existing societal inequalities.

Machine learning relies on vast amounts of data, often personal and sensitive in nature. The unregulated use of such data raises concerns about privacy infringements, data breaches, and the potential misuse of personal information. Clear regulations are needed to safeguard individuals' privacy and ensure responsible data handling practices.

Many machine learning algorithms operate as "black boxes," meaning their decision-making processes are not easily understandable or explainable. This lack of transparency raises concerns about accountability, as decisions made by these algorithms may have significant real-world consequences. Regulating the transparency and explainability of machine learning systems is crucial for building trust and ensuring ethical decision-making.

Machine learning models are vulnerable to adversarial attacks, where malicious actors intentionally manipulate input data to deceive or disrupt the system's functionality. Without adequate regulation, these attacks can have severe consequences, compromising security, integrity, and reliability.

Regulating machine learning is not solely about curbing potential risks; it also offers several benefits:

Proper regulation can enforce fairness and prevent discrimination by mandating algorithms to be free from biases or ensuring that any biases are identified and addressed transparently. This can promote equal opportunities and reduce inequalities in various domains, including hiring, lending, and criminal justice systems.

Regulations can enforce the development of interpretable and explainable machine learning models. This empowers individuals and organizations to understand and challenge the decisions made by algorithms, leading to increased accountability and trust.

Regulatory frameworks can provide guidelines and standards for the collection, use, and storage of data in machine learning applications. By implementing strict privacy regulations, individuals' personal information can be safeguarded, fostering trust in machine learning systems.

Regulations can mandate measures to protect machine learning systems from adversarial attacks. By establishing security standards and best practices, potential vulnerabilities can be mitigated, ensuring the reliability and integrity of these systems.

Regulating machine learning requires a nuanced approach that balances the need for oversight without stifling innovation.

Here are some potential approaches to regulating machine learning:

Establishing ethical guidelines and principles for the development and deployment of machine learning systems can provide a foundation for responsible AI practices. These guidelines can outline principles such as fairness, transparency, accountability, and privacy protection. Industry associations and organizations can play a role in developing and promoting these guidelines, while governments can incentivize compliance and provide oversight.

Requiring algorithmic audits and impact assessments can help identify potential biases, risks, and unintended consequences of machine learning algorithms. These assessments can be conducted prior to deployment and periodically thereafter to ensure ongoing compliance. Independent third-party audits and certifications can enhance credibility and trust.

Regulating the collection, use, and storage of data is crucial in machine learning. Stricter data governance regulations can ensure that personal and sensitive data is handled with care, with explicit consent from individuals. Clear guidelines on data anonymization, data retention, and data sharing can help protect privacy while enabling responsible use of data for machine learning purposes.

Regulators can require machine learning models to be transparent and explainable to stakeholders. This can be achieved through methods such as interpretable algorithms, model documentation, or providing explanations for the decisions made by the algorithms. By enabling stakeholders to understand the reasoning behind machine learning outcomes, accountability and trust can be fostered.

Establishing regulatory bodies or expanding the roles of existing bodies to oversee machine learning applications can ensure compliance with ethical standards and regulations. Certification programs can be developed to assess the adherence of machine learning systems to regulatory requirements. These bodies can also handle complaints, conduct investigations, and impose penalties for non-compliance.

Collaboration between governments, industry stakeholders, and research institutions is essential in shaping effective regulations for machine learning. International standards can be developed to provide a common framework for responsible AI practices, enabling cross-border cooperation and harmonization of regulations. Such collaboration can prevent regulatory fragmentation and ensure consistent standards across jurisdictions.

It's important to harness the benefits of machine learning while mitigating potential risks. Striking a balance between innovation and oversight is essential for the responsible and ethical use of this transformative technology.

Clear regulations can address concerns such as bias, privacy, transparency, and security, while fostering trust and accountability. By implementing appropriate frameworks and working collaboratively across sectors and jurisdictions, we can ensure that machine learning remains a powerful tool for societal progress while upholding fundamental values and protecting the welfare of individuals and communities.

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Behind the AI Veil: The Energy Intensity of Machine Learning – EnergyPortal.eu

Artificial intelligence (AI) and machine learning (ML) have been hailed as revolutionary technologies that will reshape industries, improve productivity, and enhance our daily lives. However, behind the AI veil lies a hidden cost that is often overlooked: the energy intensity of machine learning. As AI and ML applications continue to grow, so does the demand for computational power, leading to an increase in energy consumption and environmental impact. This article will delve into the energy intensity of machine learning and explore the implications of this growing concern.

Machine learning, a subset of AI, involves training algorithms to learn from data and make predictions or decisions. This process requires vast amounts of computational power, particularly for deep learning models, which use artificial neural networks to mimic the human brains decision-making process. Training these models can take days, weeks, or even months, depending on the complexity of the task and the size of the dataset. During this time, the energy consumption of the computers running these algorithms can be immense.

One of the most striking examples of the energy intensity of machine learning is the training of large-scale language models like OpenAIs GPT-3. GPT-3, which has been described as one of the most powerful language models ever created, consists of 175 billion parameters and required hundreds of powerful GPUs to train. According to a study by researchers at the University of Massachusetts Amherst, training a single large-scale AI model like GPT-3 can generate as much carbon emissions as five cars over their entire lifetimes, including manufacturing and fuel consumption.

The energy intensity of machine learning is not only an environmental concern but also a barrier to entry for smaller organizations and researchers. The cost of training large-scale models can be prohibitive, with some estimates suggesting that training GPT-3 could cost around $4.6 million in electricity alone. This creates a competitive advantage for large tech companies with deep pockets, potentially stifling innovation and exacerbating existing inequalities in the AI research community.

To address the energy intensity of machine learning, researchers and industry leaders are exploring various strategies. One approach is to develop more energy-efficient hardware, such as specialized AI chips that can perform complex calculations with less power. Companies like Google, NVIDIA, and Graphcore are at the forefront of this effort, developing custom chips designed specifically for AI and ML workloads.

Another strategy is to improve the efficiency of machine learning algorithms themselves. Researchers are exploring techniques such as pruning, quantization, and knowledge distillation, which can reduce the computational complexity of models without sacrificing performance. These techniques can help make AI models more accessible to a wider range of users and reduce the overall energy consumption of the machine learning ecosystem.

In addition to these technical solutions, there is a growing awareness of the need for more sustainable AI practices. This includes considering the environmental impact of AI research and development, as well as incorporating sustainability metrics into the evaluation of AI systems. Organizations like the Partnership on AI and the AI for Good Foundation are working to promote responsible AI development and ensure that the benefits of AI are shared broadly across society.

In conclusion, the energy intensity of machine learning is a critical issue that must be addressed as AI and ML technologies continue to advance. By developing more energy-efficient hardware, improving the efficiency of algorithms, and promoting sustainable AI practices, the AI research community can help mitigate the environmental impact of machine learning and ensure that these transformative technologies are accessible to all. As we continue to push the boundaries of AI and ML, it is essential that we also consider the hidden costs behind the AI veil and work towards a more sustainable future for our planet.

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Bridging the Gap: Machine Learning Applications for Brain Tumour … – Digital Journal

PRESS RELEASE

Published June 17, 2023

Background

A brain tumour can be defined as the uncontrolled development of cancerous cells in the brain. According to previous research, if left unchecked, a brain tumour can lead to cancer. Therefore, it is essential for a radiologist to be accurate about the existence of brain tumours from magnetic resonance images (MRI) for their analysis.

With the advent of e-health and machine/deep learning techniques, medical specialists are able to provide better health care and quick responses to their patients. Using machine learning (ML) techniques, an ML model can be trained to know if brain tumours are in MRI images. Machine learning is a branch of artificial intelligence that can by themselves learn how to solve specific problems if given the right access to data. Furthermore, ML has been effective in making decisions and predictions from data produced by healthcare industries.

This article will critically review different ML pipelines and models used in detecting brain tumours from MRI images and evaluate their strengths and limitations. The datasets used for analysis in this article are the T1-CE MRI image dataset, TCIA (The Cancer Imaging Archive), and Rembrandt database for brain cancer imaging.

Methods and analysis

In this article, a deep neural network called Convolutional neural network and two traditional machine learning algorithms called K-Nearest Neighbours and Nave Bayes' for detecting cancer tumours in the human brain using MRI images in this study.

Method 1.

Convolutional Neural Networks (CNN):

A Convolutional Neural network is a method of deep learning that uses convolutions on a kernel that slides through an image and produces a feat map to better understand segments and objects within an image. A convolutional neural network is used here to segment brain tumour into one of various four classes:

This article will not emphasise which architecture performs best, but on some aspects that are worth taking note of when training a CNN.

A CNN's basic structure consists of an input image, a kernel or filter (usually a 3 x3) matrix that slides horizontally across the image repeatedly moving X strides at a time and generating an output. The weights are then adjusted depending on how alike the newly generated feature map compares to the original input image. The basic structure might sound simple, but many actors come into play for the algorithm to be able to segment and locate brain tumour cells accurately. This study summarizes some of these aspects:

CNN architecture: figure 1 below shows the CNN architecture used to classify the different tumours.

The figure above shows how the CNN architecture processes an image pixel by pixel and automatically extracts the features needed and classifies the tumours using one of four different labels from 0 to 3; 0 healthy region, 1 meningioma tumour, 2 glioma tumour, and 3 pituitary tumour.

Overfitting: This is a very important issue for CNN. When the machine learning algorithm overlearns or memorises the train data, it cannot generalise properly on unseen data. This issue can be taken care of by using more artificially generated data in data augmentation, which is a popular method for this. Another method to avoid overfitting is using dropouts, which is dropping out a certain percentage of the neurons in the network to prevent overlearning. Other methods of dealing with this issue include batch normalisation and pooling.

Batch normalisation is a method of normalisation in the data that employs mini batches, which speeds up the training process by reducing the normal of epochs to be trained and stabilising the training process.

Pooling is another important aspect that downsizes the image and causes the machine learning algorithm to learn features on a downsized or less detailed image. Different pooling methods exist, such as max pooling, which uses the maximum value from the pool to estimate, while mean pooling uses the mean as an estimator.

As the data is non-linear, they need a function to introduce non-linearity in the data. The right activation function for this is the ReLU function or the rectilinear unit. After several layers of convolutions and rectifying using the RelU, the data is completely flattened using pooling into a columnar matrix which is then passed through a fully connected layer. Using a SoftMax activation, the fully connected layers can then be classified based on the classes initiated. The feature map gotten from this will then be used to classify MRI images based on the features it has learned. Keras API was used here as it is a framework for object detection and segmentation.

Method 2

K-Nearest Neighbours (KNN):

K-Nearest Neighbours (KNN) is a classical shallow machine learning algorithm used for brain tumour segmentation and classification. In this study, MRI images undergo segmentation via k-means clustering, an unsupervised algorithm. Features extracted from these clusters are then analyzed using the Gray level Co-Occurrence matrix (GLCM) and inputted into the KNN classifier for classification.

KNN requires extensive data pre-processing to achieve significant results. The study focuses on key pre-processing techniques, including image enhancement through filtering and resizing. Filtering techniques such as mean and median filters are employed to eliminate noise like salt and pepper, Gaussian noise, speckle, and Brownian noise.

Image segmentation involves creating clusters based on color, texture, contrast, and brightness. Cluster analysis using the unsupervised algorithm k-means facilitates easy feature extraction.

Feature extraction utilizes the Gray level Co-occurrence matrix, which measures the spatial dependence of grey-level intensities between pixels. This method has shown accurate results (89.9%) in classifying brain tumour cells using MRI images.

Once features are extracted, they are fed into the KNN classifier, with each segment representing a distinct class. The focus of this article is not on the specific configurations or steps taken by KNN for classification of the feature set.

Method 3

Nave Bayes:

The Nave Bayes algorithm is a supervised machine learning technique used for classification based on the probabilistic theory of Bayes. It assumes that all features (pixels) are independent of each other, making it suitable for applications with randomness.

Similar to the KNN method discussed earlier, the Nave Bayes algorithm requires important pre-processing steps to prepare the data for the machine learning process. The accuracy of the model heavily relies on these pre-processing steps. This article focuses on the following pre-processing techniques:

By implementing these pre-processing techniques, the Nave Bayes algorithm can be applied for accurate brain tumour classification.

After all the above pre-processing steps, the data is now ready to be fed into the Nave Bayes classification algorithm, whose configuration shall not be discussed in this article.

Discussion & evaluation

When looking at the results from the three different methods, it is clearly seen that the use of machine learning in detecting a brain tumour from MRI scans is very promising, with all three methods producing a high level of accuracy. In the classification process, model validation is used to divide the data into training and testing in order to obtain the accuracy of testing results.

The result of the three models in this study can be seen in the figure below. However, all three models were trained and tested on different datasets, which should be noted when comparing accuracy.

Final thoughts

As machine learning gains traction in technology and e-health industries, it's vital to recognize how different models and pipelines impact performance.

The deep learning model Convolutional Neural Network (CNN) outperformed K-Nearest Neighbour Network (KNN) and Nave Bayes models in this study, despite lacking spatial information and potential pooling issues. However, performance comparison was based on three distinct datasets, limiting accurate assessment.

When selecting a model, dataset characteristics like size and complexity are crucial. Deep learning models excel in large datasets with intricate patterns, but require powerful GPUs. In contrast, traditional machine learning models thrive with smaller data volumes.

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Applied UV Retains Quantiva to Integrate AI and Machine Learning Capabilities into Its PURONet and Airocide Systems – Yahoo Finance

Applied UV, Inc.

Expected by Q4 2023, PURONet and Airocide to Help Address Estimated $400 Billion a Year Post Harvest Crop Lost Due to Spoilage Along Supply Chain

MOUNT VERNON, NY , June 15, 2023 (GLOBE NEWSWIRE) -- via NewMediaWire Applied UV, Inc. (Nasdaq: AUVI) (Applied UV or the Company), a leading provider of advanced food security and air and surface disinfection technology, has engaged Quantiva, a provider of AI-driven consulting and software engineering services and solutions, to support the further development and expansion of the Companys proprietary indoor air quality monitoring software, PURONet.

The initial objective of the collaboration is to leverage Machine Learning and Artificial Intelligence to expand the capabilities of Applied UVs flagship brand, Airocide, a patented air purification technology originally co-developed by the University of Wisconsin for use by NASA to grow crops in space. The Airocide proprietary technology eliminates airborne pathogens including bacteria, viruses, pollen, mold, yeast, allergens, VOCs, and odors and is known globally for its ability to remove ethylene by utilizing Photo-catalytic Oxidation. It is currently used extensively in the post-harvest food preservation supply-chain with global end users such as Delmonte, Whole Foods and Esmerelda Farms to name a few. According to the Food and Agriculture Organization of the United Nations, there is a world-wide estimated $400 billion per year a post-harvest crop loss due to Spoilage along the supply chain.

Quantiva is working with Applied UV to harness the power of diverse data inputs and Artificial Intelligence for integration into both the Companys existing PURONet indoor air monitoring and control software, and the Companys Airocide product line. This more advanced product offering is expected to improve outcomes in the logistical supply chains of growers to distributors, transportation companies, and grocers; significantly reducing the magnitude of food spoilage and loss which adversely impacts countries, companies, and consumers around the world.

Story continues

Applied UV Founder, CEO and Director Max Munn, stated, We are excited about the opportunity to collaborate with Quantiva to advance the development of our proprietary PURONet indoor air monitoring software, particularly in the rapidly growing field of food preservation and food security. The impact of crop loss is felt all around the world, and we believe our proven Airocide brand can help mitigate this loss, improving societal outcomes globally. We look forward to our next-generation product launch which we anticipate being completed in late 2023.

According to Quativa Co-Founder and Managing Director Tammo Mueller, Our quantitative approach to decision-making involves defining and analyzing opportunities and challenges and delivering effective solutions through a rational, systematic, and scientific process, based on data, facts, and logic. The opportunity to address this global post-harvest problem is at the very core of our values, improving societal outcomes. We look forward to working closely with the team at Applied UV.

In a March 2023 presentation, Maximo Torero Cullen, Chief Economist of the United Nations Food and Agriculture Organization (FAO), detailed that approximately $400 billion of food is lost each year between harvest and retail. Moreover, a staggering 31.15% of all fruits and vegetables are lost globally due to high perishability and a lack of adequate intervention strategies. The majority of these perennial crop losses are due to spoilage and the effects ethylene has in the degradation of high value crops all along the supply chain.

Mr. Torero predicted that solutions to the global challenge of food loss and waste will require the deployment of context-appropriate and resource efficient technologies together with innovation down the food chain that leverages the collection and real-time utilization of a broad array of economic and environmental data.

For more information about the presentation, click on the following link: https://issuu.com/horticulturaposcosecha/docs/maximo_torero_cullen_current_status_of_food_loss_a

About Quantiva

Quantiva empowers businesses with groundbreaking AI-driven solutions and strategic product development, facilitating innovative growth and agility in regulated environments. Quantivas team of business-focused technologists have provided consulting and software engineering services for a long list of companies including such names as Institutional Shareholder Services (ISS), Siemens, UP Medical, Quantitative Radiology Solutions, and The United Nation. Quantiva is a hands-on, full product lifecycle technology consultancy & digital transformation solution provider with expertise in delivering innovation strategies tailored for multiple industries. Quantivas business category focus includes Banking/Finance, Commerce, Healthcare, Media Ownership & Royalty solutions, Supply Chain Management, and Critical Infrastructure solutions. Quantiva partners with clients to formulate business and product strategies all the way to final implementation, to reimagine processes and platforms to maximize efficiency, ensure legal compliance, and deliver maximum ROI. For more information on Quantiva, please visit https://www.quantiva.co/

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About Applied UV

Applied UV, Inc., provides proprietary surface and air pathogen elimination and disinfection technology focused on Improving Indoor Air Quality (IAQ), specialty LED lighting and luxury mirrors and commercial furnishings all of which serves clients globally in both the commercial and retail segments. For information on Applied UV, Inc., and its subsidiaries, please visit https://www.applieduvinc.com.

Forward-Looking Statements

The information contained herein may contain forwardlooking statements. Forwardlooking statements reflect the current view about future events. When used in this press release, the words anticipate, believe, estimate, expect, future, intend, plan, or the negative of these terms and similar expressions, as they relate to us or our management, identify forwardlooking statements. Such statements include, but are not limited to, statements contained in this press release relating to the view of management of Applied UV concerning its business strategy, future operating results and liquidity and capital resources outlook. Forwardlooking statements are based on the Companys current expectations and assumptions regarding its business, the economy and other future conditions. Because forwardlooking statements relate to the future, they are subject to inherent uncertainties, risks and changes in circumstances that are difficult to predict. The Companys actual results may differ materially from those contemplated by the forwardlooking statements. They are neither statements of historical fact nor guarantees of assurance of future performance. We caution you therefore against relying on any of these forwardlooking statements. Factors or events that could cause the Companys actual results to differ may emerge from time to time, and it is not possible for the Company to predict all of them. The Company cannot guarantee future results, levels of activity, performance, or achievements. Except as required by applicable law, including the securities laws of the United States, the Company does not intend to update any of the forwardlooking statements. References and links to websites have been provided as a convenience, and the information contained on such websites is not incorporated by reference into this press release.

For additional Company Information:

Applied UV Inc.Max MunnApplied UV Founder, CEO & Directormax.munn@sterilumen.com

Investor Relations Contact:

TraDigital IR

Kevin McGrath+1-646-418-7002kevin@tradigitalir.com

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Applied UV Retains Quantiva to Integrate AI and Machine Learning Capabilities into Its PURONet and Airocide Systems - Yahoo Finance