Sensor Observability Index: Evaluating Sensor Alignment for Task-Space Observability in Robotic Manipulators

In this paper, we propose a preliminary definition and analysis of the novel concept of sensor observability index. The goal is to analyse and evaluate the performance of distributed directional or axial-based sensors to observe specific axes in task space as a function of joint configuration in serial robot manipulators. For example, joint torque sensors are often used in serial robot manipulators and assumed to be perfectly capable of estimating end effector forces, but certain joint configurations may cause one or more task-space axes to be unobservable as a result of how the joint torque sensors are aligned. The proposed sensor observability provides a method to analyse the quality of the current robot configuration to observe the task space. Parallels are drawn between sensor observability and the traditional kinematic Jacobian for the particular case of joint torque sensors in serial robot manipulators. Although similar information can be retrieved from kinematic analysis of the Jacobian transpose in serial manipulators, sensor observability is shown to be more generalizable in terms of analysing non-joint-mounted sensors and other sensor types. In addition, null-space analysis of the Jacobian transpose is susceptible to false observability singularities. Simulations and experiments using the robot Baxter demonstrate the importance of maintaining proper sensor observability in physical interactions.Comment: 7 pages, 5 figures, conference pape

Vision- and tactile-based continuous multimodal intention and attention recognition for safer physical human-robot interaction

Employing skin-like tactile sensors on robots enhances both the safety and usability of collaborative robots by adding the capability to detect human contact. Unfortunately, simple binary tactile sensors alone cannot determine the context of the human contact -- whether it is a deliberate interaction or an unintended collision that requires safety manoeuvres. Many published methods classify discrete interactions using more advanced tactile sensors or by analysing joint torques. Instead, we propose to augment the intention recognition capabilities of simple binary tactile sensors by adding a robot-mounted camera for human posture analysis. Different interaction characteristics, including touch location, human pose, and gaze direction, are used to train a supervised machine learning algorithm to classify whether a touch is intentional or not with an F1-score of 86%. We demonstrate that multimodal intention recognition is significantly more accurate than monomodal analyses with the collaborative robot Baxter. Furthermore, our method can also continuously monitor interactions that fluidly change between intentional or unintentional by gauging the user's attention through gaze. If a user stops paying attention mid-task, the proposed intention and attention recognition algorithm can activate safety features to prevent unsafe interactions. We also employ a feature reduction technique that reduces the number of inputs to five to achieve a more generalized low-dimensional classifier. This simplification both reduces the amount of training data required and improves real-world classification accuracy. It also renders the method potentially agnostic to the robot and touch sensor architectures while achieving a high degree of task adaptability.Comment: 11 pages, 8 figures, preprint under revie

Increased phosphorylation of Cx36 gap junctions in the AII amacrine cells of RD retina

Retinal degeneration (RD) encompasses a family of diseases that lead to photoreceptor death and visual impairment. Visual decline due to photoreceptor cell loss is further compromised by emerging spontaneous hyperactivity in inner retinal cells. This aberrant activity acts as a barrier to signals from the remaining photoreceptors, hindering therapeutic strategies to restore light sensitivity in RD. Gap junctions, particularly those expressed in AII amacrine cells, have been shown to be integral to the generation of aberrant activity. It is unclear whether gap junction expression and coupling are altered in RD. To test this, we evaluated the expression and phosphorylation state of connexin36, the gap junction subunit predominantly expressed in AII amacrine cells, in two mouse models of RD, rd10 (slow degeneration) and rd1 (fast degeneration). Using Ser293-P antibody, which recognizes a phosphorylated form of connexin36, we found that phosphorylation of connexin36 in both slow and fast RD models was significantly greater than in wildtype controls. This elevated phosphorylation may underlie the increased gap junction coupling of AII amacrine cells exhibited by RD retina

Jet Noise Receptivity to Nozzle-upstream Perturbations in Compressible Heated Jets

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97078/1/AIAA2012-2259.pd

Network Deficiency Exacerbates Impairment in a Mouse Model of Retinal Degeneration

Neural oscillations play an important role in normal brain activity, but also manifest during Parkinson’s disease, epilepsy, and other pathological conditions. The contribution of these aberrant oscillations to the function of the surviving brain remains unclear. In recording from retina in a mouse model of retinal degeneration (RD), we found that the incidence of oscillatory activity varied across different cell classes, evidence that some retinal networks are more affected by functional changes than others. This aberrant activity was driven by an independent inhibitory amacrine cell oscillator. By stimulating the surviving circuitry at different stages of the neurodegenerative process, we found that this dystrophic oscillator further compromises the function of the retina. These data reveal that retinal remodeling can exacerbate the visual deficit, and that aberrant synaptic activity could be targeted for RD treatment

Dual Space Preconditioning for Gradient Descent

The conditions of relative smoothness and relative strong convexity were recently introduced for the analysis of Bregman gradient methods for convex optimization. We introduce a generalized left-preconditioning method for gradient descent, and show that its convergence on an essentially smooth convex objective function can be guaranteed via an application of relative smoothness in the dual space. Our relative smoothness assumption is between the designed preconditioner and the convex conjugate of the objective, and it generalizes the typical Lipschitz gradient assumption. Under dual relative strong convexity, we obtain linear convergence with a generalized condition number that is invariant under horizontal translations, distinguishing it from Bregman gradient methods. Thus, in principle our method is capable of improving the conditioning of gradient descent on problems with non-Lipschitz gradient or non-strongly convex structure. We demonstrate our method on p-norm regression and exponential penalty function minimization.Comment: SIAM J. Optim, accepte

Global affordability of fluoride toothpaste

<p>Abstract</p> <p>Objective</p> <p>Dental caries remains the most common disease worldwide and the use of fluoride toothpaste is a most effective preventive public health measure to prevent it. Changes in diets following globalization contribute to the development of dental caries in emerging economies. The aim of this paper is to compare the cost and relative affordability of fluoride toothpaste in high-, middle- and low-income countries. The hypothesis is that fluoride toothpaste is not equally affordable in high-, middle- and low-income countries.</p> <p>Methods</p> <p>Data on consumer prices of fluoride toothpastes were obtained from a self-completion questionnaire from 48 countries. The cost of fluoride toothpaste in high-, middle- and low-income countries was compared and related to annual household expenditure as well as to days of work needed to purchase the average annual usage of toothpaste per head.</p> <p>Results</p> <p>The general trend seems to be that the proportion of household expenditure required to purchase the annual dosage of toothpaste increases as the country's per capita household expenditure decreases. While in the UK for the poorest 30% of the population only 0.037 days of household expenditure is needed to purchase the annual average dosage (182.5 g) of the lowest cost toothpaste, 10.75 days are needed in Kenya. The proportion of annual household expenditure ranged from 0.02% in the UK to 4% in Zambia to buy the annual average amount of lowest cost toothpaste per head.</p> <p>Conclusion</p> <p>Significant inequalities in the affordability of this essential preventive care product indicate the necessity for action to make it more affordable. Various measures to improve affordability based on experiences from essential pharmaceuticals are proposed.</p

Understanding Russian Offensive Cyber to Repair Private-Public Relations in Critical Infrastructure Defense

This policy study assesses how concepts of monitoring IT (Information Technology) and OT (Operational Technology) mitigate the success of Russian Offensive Cyber Operations (OCO) against critical infrastructure. The study answers, "how can monitoring systems that surveil both IT and OT mitigate offensive Russian cyber operations against critical infrastructure?" Current scholarship shows substantial efforts to reform cyber defenses – exemplified by the US's changes since the early 2000s. Although reforms resulted in new defensive programs, they contributed to a convoluted system that made private-public cooperation difficult. Combined with technological trends that emphasized cost-efficiencies, these reforms created a contentious balance between private and public organizations where infrastructure providers valued costs over security. This unfortunate position supports Russia's strategy. Russian cyber-attacks since 2007 illustrate increasingly destructive capabilities that manipulate critical infrastructure vulnerabilities and weak defenses. This study examines Russian cyber-attacks since 2007 to test if Moscow's cyber tactics create abnormal behavioral traits that modern surveillance, IT-OT monitoring, could detect. Through comparative case studies of Russian OCO, the study builds common TTPs (Tactics, Techniques, and Procedures) and possible warning signs. The results are the foundation of several policy recommendations. The study used data from established technical trade associates, non-governmental organizations, government agencies, translated Russian strategy documents, and scholarly literature that discussed Russia's cyber activities. The analysis indicates that Russia's offensive cyber creates several observable behavioral traits that IT-OT monitoring would detect, mitigating Russian OCO's success against critical infrastructure. However, the technique needs to intervene when an attacker is in initial set-up phases, as the beginning segments of a Russian OCO are the most vulnerable to detection. The study recommends streamlining government cybersecurity and regulatory agencies, providing the necessary intelligence to customize defensive systems, and broadening access to commercial solutions. These steps would help create a collaborative relationship between the public and private sector while encouraging the broad adoption of IT-OT monitoring. The study concludes that the government should focus on policies that support industry to encourage cybersecurity modernization and avoid problems seen in America's reforms during the 2000s

Database Queries in Java

In conventional programming languages like Java, the interface for accessing databases is often inelegant. Typically, an entire separate database query language must be embedded inside a conventional programming language for programmers to access the full power and speed of a database. Programmers, though, prefer working entirely from within their conventional programming languages, both for general-purpose computation and for database access. This thesis explores how database operations can be expressed using the existing syntax of conventional programming languages. Programmers are able to write all their code –both general purpose code and database access code– in a single language. To run these database operations efficiently though, algorithms are needed for finding these database operations and optimizing them. This thesis focuses on techniques that can be easily adopted because they do not require changes to existing compilers. Three systems have been developed: Queryll, JReq, and HadoopToSQL. Each system examines the problem from the context of functional-style code, imperative-style code, and MapReduce-style code respectively