Generic system architecture for context-aware, distributed recommendation

In the existing literature on recommender systems, it is difficult to find an architecture for large-scale implementation. Often, the architectures proposed in papers are specific to an algorithm implementation or a domain. Thus, there is no clear architectural starting point for a new recommender system. This paper presents an architecture blueprint for a context-aware recommender system that provides scalability, availability, and security for its users. The architecture also contributes the dynamic ability to switch between single-device (offline), client-server (online), and fully distributed implementations. From this blueprint, a new recommender system could be built with minimal design and implementation effort regardless of the application.Electrical and Computer Engineerin

Flow-Control Effectiveness of Convergent Surface Indentations on an Aerofoil at Low Reynolds Numbers

Passive flow control on aerofoils has largely been achieved through the use of protrusions such as vane-type vortex generators. Consequently, innovative flow-control concepts should be explored in an effort to improve current component performance. Therefore, experimental research has been performed at The University of Manchester to evaluate the flow-control effectiveness of a novel type of vortex generator made in the form of a surface indentation. The surface indentation has a trapezoidal planform. A spanwise array of indentations has been applied in a convergent orientation around the maximum-thickness location of the upper surface of a NACA-0015 aerofoil. The aerofoil has been tested in a twodimensional set-up in a low-speed wind tunnel at an angle of attack (AoA) of 3° and a chordbased blockage-corrected Reynolds number (Recorr) of ~2.70 x 105 . The baseline model has been found to suffer from a long laminar separation bubble (LSB) at low AoA. The application of the indentations at low AoA has considerably shortened the separation bubble. The indentations achieve this by shedding up-flow pairs of streamwise vortices. Despite the considerable reduction in bubble length, the increase in leading-edge suction due to the shorter bubble is limited by the removal of surface curvature and blockage (increase in surface pressure) caused locally by the convergent indentations. Furthermore, the up-flow region of the vortices, which locally weakens the pressure recovery around the trailing edge of the aerofoil by thickening the boundary layer, also contributes to this limitation. Due to the conflicting effects of the indentations, the changes in the pressure-lift and pressure-drag coefficients, i.e., cl,p and cd,p, respectively, are small. Nevertheless, the indentations have improved cl,p and cd,p beyond the uncertainty range, i.e., by ~1.3% and ~0.3%, respectively, at 3° AoA. The wake measurements show that turbulence intensity and Reynolds stresses have considerably increased in the indented case, thus implying that the indentations increase the viscous drag on the model. In summary, the convergent indentations are able to reduce the size of the LSB, but conversely, they are not highly effective in enhancing cl,p and cd,p at the tested Re

COBOL Cripples The Mind!: Academia and the Alienation of Data Processing

This paper writes a social history of the programming language COBOL that focuses on its reception in academia. Through this focus, the paper seeks to understand the contentious relationship between data processing and the academy. In historicizing COBOL, the paper also illuminates the changing nature of the academy-industry-military triangle that was a mainstay of early computing

Development and Construct Validation of the Pharmacists\u27 Care of Migraineurs Scale

To develop and determine construct validity of the pharmacists\u27 care of migraineurs scale (PCMS) an initial set of domains and items were derived from a review of the literature and from the results of focus groups with community pharmacists and migraineurs. Results from a nationwide sample of community pharmacists yielded a seven-factor solution including the following domains: empathy, prospective drug utilization review for newly diagnosed migraineurs, medication counseling, non-pharmacologic treatment plan, headache sufferer triage, dissemination of public health information and maintenance of knowledge on migraine. Evidence supported the construct validity and reliability of the PCMS. The PCMS may be used to instruct pharmacists\u27 care of migraineurs and may prove useful in benchmarking care pursuant to educational interventions. Further study evaluating the utility of the PMCS is warranted

A Multi-Plane Block-Coordinate Frank-Wolfe Algorithm for Training Structural SVMs with a Costly max-Oracle

Structural support vector machines (SSVMs) are amongst the best performing models for structured computer vision tasks, such as semantic image segmentation or human pose estimation. Training SSVMs, however, is computationally costly, because it requires repeated calls to a structured prediction subroutine (called \emph{max-oracle}), which has to solve an optimization problem itself, e.g. a graph cut. In this work, we introduce a new algorithm for SSVM training that is more efficient than earlier techniques when the max-oracle is computationally expensive, as it is frequently the case in computer vision tasks. The main idea is to (i) combine the recent stochastic Block-Coordinate Frank-Wolfe algorithm with efficient hyperplane caching, and (ii) use an automatic selection rule for deciding whether to call the exact max-oracle or to rely on an approximate one based on the cached hyperplanes. We show experimentally that this strategy leads to faster convergence to the optimum with respect to the number of requires oracle calls, and that this translates into faster convergence with respect to the total runtime when the max-oracle is slow compared to the other steps of the algorithm. A publicly available C++ implementation is provided at http://pub.ist.ac.at/~vnk/papers/SVM.html

Numerical Simulation of a Cryogenic Spray

Cryogenic sprays have many applications in modern engineering. Cooling of electronic equipment subject to high heat flows, surgical ablation of gastrointestinal mucosae or orbital maneuvering are a few examples of their versatility. However, the atomization of a cryogenic liquid is a complex process. During such an event, aerodynamic effects associated with secondary atomization are further affected by thermodynamic flashing. A better understanding of the characteristics of cryogenic sprays is then necessary to allow for improved design and optimization in applications. The overarching objective of this study is to document such characteristics. The numerical simulation was performed over cryogenic nitrogen spray using an Eulerian-Lagrangian approach. In other words, while the gas phase of the flow is treated as a continuum, the nitrogen droplets are tracked individually in a Lagrangian sense. Models for evaporation, atomization, and breakups capture the physical processes experienced by droplets along their pathways. In addition, turbulence in the flow is captured by the k-omega SST model. Simulations performed over a wide range of nozzle inlet pressure suggest that the spray cone angle tends to remain constant. In contrast, the diameter of droplets along the centerline of the spray reduces significantly. Finally, it was noticed that a higher concentration of liquid nitrogen is observed on a target plate as the nozzle inlet pressure increases

Split Inteins: From Mechanistic Studies to Novel Protein Engineering Technologies

Inteins are auto-processing protein domains that carry out a post-translational process known as protein splicing. This process is characterized by excision of the intein (intervening protein) domain from within a larger polypeptide sequence with concomitant ligation of the flanking extein ( external protein) regions through a native peptide bond. Remarkably, a small subset of all inteins are naturally transcribed and translated as two fragments that efficiently associate and carry out the same biochemical process in trans, and these split inteins are potentially powerful tools for protein engineering. Recently, a split intein from the cyanobacterium Nostoc punctiforme (Npu) was discovered that can carry out protein splicing with a half-life of one minute, as opposed to hours as seen for previously characterized split and contiguous inteins. Inspired by the apparent uniqueness of this “ultrafast” splicing activity and its practical implications, we characterized several orthologous split inteins from the same family as Npu. Surprisingly, many of these inteins splice as quickly as Npu, and biochemical characterization of this family divulged sequence-activity correlations that provided insights into the molecular determinants for fast protein trans-splicing. Importantly, several of these inteins are extraordinarily efficient in their first auto-processing step, peptide bond cleavage coupled to thioester formation. Harnessing this property, along with efficient fragment association, a streamlined iteration of Expressed Protein Ligation (EPL), the most prevalent protein semi-synthesis technique, was developed. Further insights into protein splicing were obtained by the development of a novel kinetic assay that allowed for quantitative observation of a crucial intermediate in the protein splicing pathway, the branched intermediate (BI). Using this assay, BI resolution was unambiguously identified as the rate limiting step for Npu splicing. Furthermore, the roles of extein residues in individual steps along the splicing pathway were teased apart. Using protein semi-synthesis, kinetic measurements, and structural techniques, C-extein composition was found to be intimately linked to active-site dynamics and BI resolution kinetics. In addition to chemical reactivity, the fragment assembly of Npu was also characterized. Mutation of charged residues at the binding interface demonstrated that split intein binding affinity was dominated by intermolecular electrostatic interactions. By swapping charged residues between the intein fragments, a new split intein was engineered with orthogonal binding and reactivity to the wild-type Npu split intein. The wild-type and charges wapped inteins could be used in protein semi-synthesis endeavors requiring parallel selective splicing reactions in one pot. Finally, using a combination of biophysical techniques, the mechanism of split intein assembly was elucidated. Our analyses indicated that the assembly follows a unique trajectory comprised of coupled binding and folding of disordered regions of each fragment followed by a collapse of the structure into a stable functional domain. Collectively, these structural and functional studies not only provide insights into the inner workings of inteins but will also continue to aid in the development of important protein engineering technologies

Human-Machine Collaborative Optimization via Apprenticeship Scheduling

Coordinating agents to complete a set of tasks with intercoupled temporal and resource constraints is computationally challenging, yet human domain experts can solve these difficult scheduling problems using paradigms learned through years of apprenticeship. A process for manually codifying this domain knowledge within a computational framework is necessary to scale beyond the ``single-expert, single-trainee" apprenticeship model. However, human domain experts often have difficulty describing their decision-making processes, causing the codification of this knowledge to become laborious. We propose a new approach for capturing domain-expert heuristics through a pairwise ranking formulation. Our approach is model-free and does not require enumerating or iterating through a large state space. We empirically demonstrate that this approach accurately learns multifaceted heuristics on a synthetic data set incorporating job-shop scheduling and vehicle routing problems, as well as on two real-world data sets consisting of demonstrations of experts solving a weapon-to-target assignment problem and a hospital resource allocation problem. We also demonstrate that policies learned from human scheduling demonstration via apprenticeship learning can substantially improve the efficiency of a branch-and-bound search for an optimal schedule. We employ this human-machine collaborative optimization technique on a variant of the weapon-to-target assignment problem. We demonstrate that this technique generates solutions substantially superior to those produced by human domain experts at a rate up to 9.5 times faster than an optimization approach and can be applied to optimally solve problems twice as complex as those solved by a human demonstrator.Comment: Portions of this paper were published in the Proceedings of the International Joint Conference on Artificial Intelligence (IJCAI) in 2016 and in the Proceedings of Robotics: Science and Systems (RSS) in 2016. The paper consists of 50 pages with 11 figures and 4 table

Queueing Theory Analysis of Labor & Delivery at a Tertiary Care Center

Labor and Delivery is a complex clinical service requiring the support of highly trained healthcare professionals from Obstetrics, Anesthesiology, and Neonatology and the access to a finite set of valuable resources. In the United States, the rate of cesarean sections on labor floors is approximately twice as high as considered appropriate for patient care. We analyze one month of data from a Boston-area hospital to assess how well the labor and delivery process can be modelled with tools from queueing theory. We find that the labor and delivery process is highly amenable to analysis under queueing theory models. We also investigate the problem of high cesarean section rates and the potential effects of resource utilization of lowering the rate of cesarean section

Extracorporeal support prognostication-time to move the goal posts?

Advances in extracorporeal membrane oxygenation (ECMO) technology are associated with expanded indications, increased utilization and improved outcome. There is growing interest in developing ECMO prognostication scores to aid in bedside decision making. To date, the majority of available scores have been limited to mostly registry-based data and with mortality as the main outcome of interest. There continues to be a gap in clinically applicable decision support tools to aid in the timing of ECMO cannulation to improve patients\u27 long-term outcomes. We present a brief review of the commonly available adult and pediatric ECMO prognostication tools, their limitations, and future directions