cssi/SciSciGPT-SciSciNet huggingface dataset:
grim: A Flexible, Conservative Scheme for Relativistic Fluid Theories

Hot, diffuse, relativistic plasmas such as sub-Eddington black-hole accretion flows are expected to be collisionless, yet are commonly modeled as a fluid using ideal general relativistic magnetohydrodynamics (GRMHD). Dissipative effects such as heat conduction and viscosity can be important in a collisionless plasma and will potentially alter the dynamics and radiative properties of the flow from that in ideal fluid models; we refer to models that include these processes as Extended GRMHD. Here we describe a new conservative code, grim, that enables all of the above and additional physics to be efficiently incorporated. grim combines time evolution and primitive variable inversion needed for conservative schemes into a single step using an algorithm that only requires the residuals of the governing equations as inputs. This algorithm enables the code to be physics agnostic as well as flexibility regarding time-stepping schemes. grim runs on CPUs, as well as on GPUs, using the same code. We formulate a performance model and use it to show that our implementation runs optimally on both architectures. grim correctly captures classical GRMHD test problems as well as a new suite of linear and nonlinear test problems with anisotropic conduction and viscosity in special and general relativity. As tests and example applications, we resolve the shock substructure due to the presence of dissipation, and report on relativistic versions of the magneto-thermal instability and heat flux driven buoyancy instability, which arise due to anisotropic heat conduction, and of the firehose instability, which occurs due to anisotropic pressure (i.e., viscosity). Finally, we show an example integration of an accretion flow around a Kerr black hole, using Extended GRMHD.
Decoder Error Probability of MRD Codes

In this paper, we first introduce the concept of elementary linear subspace, which has similar properties to those of a set of coordinates. Using this new concept, we derive properties of maximum rank distance (MRD) codes that parallel those of maximum distance separable (MDS) codes. Using these properties, we show that the decoder error probability of MRD codes with error correction capability t decreases exponentially with t2 based on the assumption that all errors with the same rank are equally likely. We argue that the channel based on this assumption is an approximation of a channel corrupted by crisscross errors.
Analysis of envelope signal injection for improvement of RF amplifier intermodulation distortion

Adaptive bias techniques based on envelope signal power detection have been proposed for linearity enhancement and dc current reduction in RF amplifiers. Experimental results show an improvement in amplifier linearity, although asymmetric intermodulation distortion (IMD) was observed. This work rigorously studies the effects of the envelope signal injection on amplifier distortion using the Volterra series formulations. The results intuitively explain the spectral regrowth asymmetry, and point to a design technique in which third-order IMD can be optimally cancelled. The theory was verified through comparison to measurement and simulation results.
Evidence of Large Empty Lava Tubes on the Moon using GRAIL Gravity

NASA's GRAIL mission employed twin spacecraft in polar orbits around the Moon to measure the lunar gravity field at unprecedentedly high accuracy and resolution. The low spacecraft altitude in the extended mission enables the detection of small-scale surface or subsurface features. We analyzed these data for evidence of empty lava tubes beneath the lunar maria. We developed two methods, gradiometry and cross-correlation, to isolate the target signal of long, narrow, sinuous mass deficits from a host of other features present in the GRAIL data. Here, we report the discovery of several strong candidates that are either extensions of known lunar rilles, collocated with the recently discovered “skylight” caverns, or underlying otherwise unremarkable surfaces. Owing to the spacecraft polar orbits, our techniques are most sensitive to east-west trending near-surface structures and empty lava tubes with minimum widths of several kilometers, heights of hundreds of meters, and lengths of tens of kilometers.
Sub-mm wave imaging techniques for non-destructive aerospace materials evaluation

A millimeter and sub-millimeter continuous wave system has been used to image corrosion pitting, structural defects, and heat damage in common aircraft materials such as aluminum and polyamides. In order to avoid failure of components during operation, many aircraft parts are replaced earlier than necessary leading to higher costs that could be reduced if the degree of damage in the component material could be determined non-destructively. Millimeter and Sub-millimeter waves are ideally suited for this purpose because of their ability to penetrate through dielectric substances and obscurants such as pain, oil, and epoxy commonly found on the surfaces of aircraft.
Nuclear structure and reactions with stored nuclei

Abstract The use of ion-storage rings is discussed for studies of nuclear reactions and structure, with emphasis on energetic beams of short-lived, radioactive nuclei. Aspects of internal versus external luminosity are considered as well as other issues connected with the inverse kinematics of reactions induced by a circulating beam of complex nuclei. Some of the physics motivation that is driving studies with radioactive beams is described.
Golf ball mark severity and recovery as affected by mowing height, rolling frequency, foot traffic, and moisture

Putting greens experience stress from golf balls striking the surface, maintenance equipment, and foot traffic. Improved creeping bentgrass (Agrostis stolonifera L.) cultivars, sand-based root zones, and skilled superintendents maintain plant health while providing firmer conditions. Many researchers have studied effects of compaction and wear on putting greens, but few have determined the effect of these stresses on ball marks. The objective of this research was to evaluate ball mark severity and recovery of creeping bentgrass under different mowing heights (2.5, 3.2, and 4.0 mm), rolling frequencies (0, 3, or 6 d wk–¹), and foot traffic using digital image analysis. Digital images of golf balls placed in the depression were used to calculate ball mark depth, and a cover analysis was conducted to model ball mark injury area using a one phase decay model to determine theoretical maximum injury, slope, and days to 50% recovery. Soil moisture content was positively correlated with ball mark depth, but common stresses rarely altered ball mark depth. The mean theoretical maximum ball mark injury was 377 mm² greater for daily rolled treatments in 2010 compared to non-rolled treatments. The slope of recovery rarely changed among treatments suggesting that theoretical maximum ball mark injury area has a greater effect on recovery. Lastly, combining the lowest mowing height or daily rolling and foot traffic slowed the time ball marks took to reach 50% recovery. This research demonstrates the effects common management practices and soil moisture have on the severity and recovery of ball marks during environmental stress.
On Indescribable Contingencies and Incomplete Contracts

Abstract I examine the theoretical foundations underlying the incomplete contracts literature. A common justification for the assumption that contracts are not fully contingent on the state of nature is to point out that some aspects of the state may be unforeseen or indescribable to the contracting partners at the time the contract is written. I argue, however, that as long as risk-averse parties can foresee the probabilities of their possible payoffs, then the fact that they cannot describe the possible physical states does not matter; even with renegotiation, the parties can attain the same welfare as when full description is possible.
Physical Activity Education: The New Name for Our Field

This article is a follow-up to a previous Viewpoint article, wherein the authors challenged the oft-cited distinction between physical education and physical activity, and proposed an alternate definition of physical education that is aligned with the need to promote physical activity in schools.
Applications of nuclear physics

Today the applications of nuclear physics span a very broad range of topics and fields. This review discusses a number of aspects of these applications, including selected topics and concepts in nuclear reactor physics, nuclear fusion, nuclear non-proliferation, nuclear-geophysics, and nuclear medicine. The review begins with a historic summary of the early years in applied nuclear physics, with an emphasis on the huge developments that took place around the time of World War II, and that underlie the physics involved in designs of nuclear explosions, controlled nuclear energy, and nuclear fusion. The review then moves to focus on modern applications of these concepts, including the basic concepts and diagnostics developed for the forensics of nuclear explosions, the nuclear diagnostics at the National Ignition Facility, nuclear reactor safeguards, and the detection of nuclear material production and trafficking. The review also summarizes recent developments in nuclear geophysics and nuclear medicine. The nuclear geophysics areas discussed include geo-chronology, nuclear logging for industry, the Oklo reactor, and geo-neutrinos. The section on nuclear medicine summarizes the critical advances in nuclear imaging, including PET and SPECT imaging, targeted radionuclide therapy, and the nuclear physics of medical isotope production. Each subfield discussed requires a review article unto itself, which is not the intention of the current review; rather, the current review is intended for readers who wish to get a broad understanding of applied nuclear physics.
Detectivity limits for diffused junction PbSnTe detectors

Abstract The resistance-area product ( R 0 A ) of diffused junction PbSnTe photo-voltaic detectors under conditions of zero bias voltage is calculated for linearly graded and one-sided abrupt junctions. Equations are developed to demonstrate the overall dependence of R 0 A on grading constant when minority carrier diffusion current, depletion layer current, and tunneling current are taken into account for the linearly graded junction. Similarly, for the one-sided abrupt junction the dependence of R 0 A on the carrier concentration of the lightly doped side is shown for the diffusion, depletion, and tunneling mechanisms. The calculations are carried out for two devices of practical interest: Pb 0.982 Sn 0.018 Te diffused with Sb with a 5 μm cutoff at an operating temperature of 170°K, and Pb 0.79 Sn 0.21 Te diffused with Cd with an 11 μm cutoff at 77°K. The junctions formed by Sb diffusion obey the linearly graded model, whereas the Cd junctions formed in unannealed substrates are one-sided abrupt. Upon comparing measured R 0 A products with calculated values, we have established approximate values for the lifetimes within the depletion layers for each of these devices. The consequences of these results for the thermal noise-limited detectivity ( D ∗ ) of these detectors are shown by plotting D ∗ vs R 0 A . Within this framework, it can be argued that the inherently short lifetimes of PbSnTe play the dominant role in placing the upper limits on achievable D ∗ .
Inhibition of the Aldehyde Dehydrogenase 1/2 Family by Psoralen and Coumarin Derivatives.

Aldehyde dehydrogenase 2 (ALDH2), one of 19 ALDH superfamily members, catalyzes the NAD+-dependent oxidation of aldehydes to their respective carboxylic acids. In this study, we further characterized the inhibition of four psoralen and coumarin derivatives toward ALDH2 and compared them to the ALDH2 inhibitor daidzin for selectivity against five ALDH1/2 isoenzymes. Compound 2 (Ki = 19 nM) binds within the aldehyde-binding site of the free enzyme species of ALDH2. Thirty-three structural analogs were examined to develop a stronger SAR profile. Seven compounds maintained or improved upon the selectivity toward one of the five ALDH1/2 isoenzymes, including compound 36, a selective inhibitor for ALDH2 (Ki = 2.4 μM), and compound 32, which was 10-fold selective for ALDH1A1 (Ki = 1.2 μM) versus ALDH1A2. Further medicinal chemistry on the compounds’ basic scaffold could enhance the potency and selectivity for ALDH1A1 or ALDH2 and generate chemical probes to examine the unique and overlapping functions of the ALD...
Robust video communication by combining scalability and multiple description coding techniques

Layered coding (LC) and multiple description coding (MDC) have been proposed as two different kinds of 'quality adaptation' schemes for video delivery over the current Internet or wireless networks. To combine the advantages of LC and MDC, we present a new approach -- Multiple Description Layered Coding (MDLC), to provide reliable video communication over a wider range of network scenarios and application requirements. MDLC improves LC in that it introduces redundancy in each layer so that the chance of receiving at least one description of base layer is greatly enhanced. Though LC and MDC are each good in limit cases (e.g., long end-to-end delay for LC vs. short delay for MDC), the proposed MDLC system can address intermediate cases as well. Same as a LC system with retransmission, the MDLC system can have a feedback channel to indicate which descriptions have been correctly received. Thus a low redundancy MDLC system can be implemented with our proposed runtime packet scheduling system based on the feedback information. The goal of our scheduling algorithm is to find a proper on-line packet scheduling policy to maximize the playback quality at the decoder. Previous work on scheduling algorithms has not considered multiple decoding choices due to the redundancy between data units, because of the increase in complexity involved in considering alternate decoding paths. In this paper, we introduce a new model of Directed Acyclic HyperGraph (DAHG) to represent the data dependencies among frames and layers, as well as the data correlation between descriptions. The impact of each data unit to others is represented by messages passing along the graph with updates based on new information received. Experimental results show that the proposed system provides more robust and efficient video communication for real-time applications over lossy packet networks.
Leavitt path algebras: the first decade

The algebraic structures known as Leavitt path algebras were initially developed in 2004 by Ara, Moreno and Pardo, and almost simultaneously (using a different approach) by the author and Aranda Pino. During the intervening decade, these algebras have attracted significant interest and attention, not only from ring theorists, but from analysts working in C ∗ -algebras, group theorists, and symbolic dynamicists as well. The goal of this article is threefold: to introduce the notion of Leavitt path algebras to the general mathematical community; to present some of the important results in the subject; and to describe some of the field’s currently unresolved questions.
A microRNA family exerts maternal control on sex determination in C. elegans

Gene expression in early animal embryogenesis is in large part controlled post-transcriptionally. Maternally contributed microRNAs may therefore play important roles in early development. We elucidated a major biological role of the nematode mir-35 family of maternally contributed essential microRNAs. We show that this microRNA family regulates the sex determination pathway at multiple levels, acting both upstream of and downstream from her-1 to prevent aberrantly activated male developmental programs in hermaphrodite embryos. Both of the predicted target genes that act downstream from the mir-35 family in this process, suppressor-26 (sup-26) and NHL (NCL-1, HT2A, and LIN-41 repeat) domain-containing-2 (nhl-2), encode RNA-binding proteins, thus delineating a previously unknown post-transcriptional regulatory subnetwork within the well-studied sex determination pathway of Caenorhabditis elegans Repression of nhl-2 by the mir-35 family is required for not only proper sex determination but also viability, showing that a single microRNA target site can be essential. Since sex determination in C. elegans requires zygotic gene expression to read the sex chromosome karyotype, early embryos must remain gender-naive; our findings show that the mir-35 family microRNAs act in the early embryo to function as a developmental timer that preserves naivete and prevents premature deleterious developmental decisions.
Special study on benchmarking the quality of project economic analysis for the South Asia Region

This paper benchmarks the quality of project economic analysis in South Asia against other World Bank regions, using data on project exits between 1975 and 2015. The results show that the South Asia region performs on par with the other regions, in that the share of project documents that report estimated economic rates of return have declined from 70 to 36 percent for South Asia and the other regions. This finding suggests there is less attention to project economic analysis (especially for sectors where this has been a traditional practice, such as energy, transport, water, and agriculture). The finding also indicates that the incidence of reporting rates of return in project documents and the dispersion or difference between rates of return estimated at project appraisal and completion are significantly correlated with project performance (after correcting for country- and project-level variables). For the project-level variables, the task team effect is a key variable that explains project outcomes. The paper discusses the implications of the analyses for strengthening project performance and risk mitigation.
Deterministic extractors for small-space sources

We give polynomial-time, deterministic randomness extractors for sources generated in small space, where we model space s sources on {0,1}^n as sources generated by width 2^s branching programs. Specifically, there is a constant @h>0 such that for any @z>n^-^@h, our algorithm extracts m=(@d-@z)n bits that are exponentially close to uniform (in variation distance) from space s sources with min-entropy @dn, where s=@W(@z^3n). Previously, nothing was known for @d=<1/2, even for space 0. Our results are obtained by a reduction to the class of total-entropy independent sources. This model generalizes both the well-studied models of independent sources and symbol-fixing sources. These sources consist of a set of r independent smaller sources over {0,1}^@?, where the total min-entropy over all the smaller sources is k. We give deterministic extractors for such sources when k is as small as polylog(r), for small enough @?.
Limit Theorems for Marked Hawkes Processes with Application to a Risk Model

This article focuses on limit theorems for linear Hawkes processes with random marks. We prove a large deviation principle, which answers the question raised by Bordenave and Torrisi. A central limit theorem is also obtained. We conclude with an example of application in finance.
Developing a Comprehensive Framework for Multimodal Feature Extraction

Feature extraction is a critical component of many applied data science workflows. In recent years, rapid advances in artificial intelligence and machine learning have led to an explosion of feature extraction tools and services that allow data scientists to cheaply and effectively annotate their data along a vast array of dimensions--ranging from detecting faces in images to analyzing the sentiment expressed in coherent text. Unfortunately, the proliferation of powerful feature extraction services has been mirrored by a corresponding expansion in the number of distinct interfaces to feature extraction services. In a world where nearly every new service has its own API, documentation, and/or client library, data scientists who need to combine diverse features obtained from multiple sources are often forced to write and maintain ever more elaborate feature extraction pipelines. To address this challenge, we introduce a new open-source framework for comprehensive multimodal feature extraction. Pliers is an open-source Python package that supports standardized annotation of diverse data types (videos, images, audio, and text), and is expressly implemented with both ease-of-use and extensibility in mind. Users can apply a wide range of pre-existing feature extraction tools to their data in just a few lines of Python code, and can also easily add their own custom extractors by writing modular classes. A graph-based API enables rapid development of feature extraction pipelines that output results in a single, standardized format. We describe the package's architecture, detail its advantages over previous feature extraction toolboxes, and use a sample application to a large functional MRI dataset to illustrate how pliers can significantly reduce the time and effort required to construct simple feature extraction workflows while increasing code clarity and maintainability.
Estimated Perinatal HIV Infection Among Infants Born in the United States, 2002-2013.

Importance Perinatal transmission of human immunodeficiency virus (HIV) can be reduced through services including antiretroviral treatment and prophylaxis. Data on the national incidence of perinatal HIV transmission and missed prevention opportunities are needed to monitor progress toward elimination of mother-to-child HIV transmission. Objective To estimate the number of perinatal HIV cases among infants born in the United States. Design, Setting, and Participants Data were obtained from the National HIV Surveillance System on infants with HIV born in the United States (including the District of Columbia) and their mothers between 2002 and 2013 (reported through December 31, 2015). Estimates were adjusted for delay in diagnosis and reporting by weighting each reported case based on a model incorporating time from birth to diagnosis and report. Analysis was performed from April 1 to August 15, 2016. Exposures Maternal HIV infection and antiretroviral medication, including maternal receipt prenatally or during labor/delivery and infant receipt postnatally. Main Outcomes and Measures Diagnosis of perinatally acquired HIV infection in infants born in the United States. Infant and maternal characteristics, including receipt of perinatal HIV testing, treatment, and prophylaxis. Results The estimated annual number of perinatally infected infants born in the United States decreased from 216 (95% CI, 206-230) in 2002 to 69 (95% CI, 60-83) in 2013. Among perinatally HIV-infected children born in 2002-2013, 836 (63.0%) of the mothers identified as black or African American and 243 (18.3%) as Hispanic or Latino. A total of 236 (37.5%) of the mothers had HIV infection diagnosed before pregnancy in 2002-2005 compared with 120 (51.5%) in 2010-2013; the proportion of mother-infant pairs receiving all 3 recommended arms of antiretroviral prophylaxis or treatment (prenatal, intrapartum, and postnatal) was 22.4% in 2002-2005 and 31.8% in 2010-2013, with approximately 179 (28.4%) (2002-2005) and 94 (40.3%) (2010-2013) receiving antiretroviral prophylaxis or treatment during pregnancy. Five Southern states (Florida, Texas, Georgia, Louisiana, and Maryland) accounted for 687 (38.0%) of infants born with HIV infection in the United States during the overall period. According to national data for live births, the incidence of perinatal HIV infection among infants born in the United States in 2013 was 1.75 per 100 000 live births. Conclusions and Relevance Despite reduced perinatal HIV infection in the United States, missed opportunities for prevention were common among infected infants and their mothers in recent years. As of 2013, the incidence of perinatal HIV infection remained 1.75 times the proposed Centers for Disease Control and Prevention elimination of mother-to-child HIV transmission goal of 1 per 100 000 live births.
LaraDB: A Minimalist Kernel for Linear and Relational Algebra Computation

Analytics tasks manipulate structured data with variants of relational algebra (RA) and quantitative data with variants of linear algebra (LA). The two computational models have overlapping expressiveness, motivating a common programming model that affords unified reasoning and algorithm design. At the logical level we propose LARA, a lean algebra of three operators, that expresses RA and LA as well as relevant optimization rules. We show a series of proofs that position LARA at just the right level of expressiveness for a middleware algebra: more explicit than MapReduce but more general than RA or LA. At the physical level we find that the LARA operators afford efficient implementations using a single primitive that is available in a variety of backend engines: range scans over partitioned sorted maps.To evaluate these ideas, we implemented the LARA operators as range iterators in Apache Accumulo, a popular implementation of Google's BigTable. First we show how LARA expresses a sensor quality control task, and we measure the performance impact of optimizations LARA admits on this task. Second we show that the LARADB implementation outperforms Accumulo's native MapReduce integration on a core task involving join and aggregation in the form of matrix multiply, especially at smaller scales that are typically a poor fit for scale-out approaches. We find that LARADB offers a conceptually lean framework for optimizing mixed-abstraction analytics tasks, without giving up fast record-level updates and scans.
An efficient curing policy for epidemics on graphs

This paper provides an implementable dynamic policy for the rapid containment of a contagious process modeled as an SIS epidemic. We show that for graphs with low CutWidth (sublinear) rapid containment defined as achieving sublinear expected extinction time for the epidemic is feasible with sublinear budget and is achieved by this policy.
Rotavirus Vaccination and the Risk of Celiac Disease or Type 1 Diabetes in Finnish Children at Early Life

Background:Rotavirus infection has been suggested as a trigger of type 1 diabetes (T1D)-related autoimmunity and celiac disease (CD)-related autoimmunity.Methods:We carried out a nationwide, population-based cohort study evaluating whether prevention of rotavirus infection with vaccination affects t
Further Characterization of the Mitigation of Radiation Lethality by Protective Wounding

There continues to be a major effort in the United States to develop mitigators for the treatment of mass casualties that received high-intensity acute ionizing radiation exposures from the detonation of an improvised nuclear device during a radiological terrorist attack. The ideal countermeasure should be effective when administered after exposure, and over a wide range of absorbed doses. We have previously shown that the administration of a subcutaneous incision of a defined length, if administered within minutes after irradiation, protected young adult female C57BL/6 mice against radiation-induced lethality, and increased survival after total-body exposure to an LD50/30 X-ray dose from 50% to over 90%. We refer to this approach as “protective wounding”. In this article, we report on our efforts to further optimize, characterize and demonstrate the validity of the protective wounding response by comparing the response of female and male mice, varying the radiation dose, the size of the wound, and the ti...
The role of corporate governance for acquisitions by the emerging market multinationals: Evidence from India

Abstract Acquisitions by emerging market firms of targets located in developed markets have increased drastically over the recent years. We use this setting to test Coffee's (1999) bonding hypothesis in a cross-border M&A context by examining whether acquirers adopt the corporate governance practices prevalent in the target's country. Using firm-level data spanning 2001–2010, we find that (i) ownership and board characteristics of Indian firms change significantly after acquiring developed market targets, (ii) the change in firm governance is more pronounced when the target countries have better investor protection and (iii) acquirers that exhibit changes in firm governance are associated with higher valuation after these transactions. These findings suggest that emerging market firms bond to higher corporate governance standards of the developed markets through cross-border acquisitions.
Uncertainty, learning, and local opposition to hydraulic fracturing

Abstract New extraction technologies, including hydraulic fracturing (fracking), have increased fossil fuel reserves in the United States. Despite local economic benefits, many jurisdictions have adopted bans on fracking. We develop a dynamic learning model parameterized with a computable general equilibrium (CGE) model to quantify the associated quasi-option value (QOV), and to explore if uncertainty about environmental damages with the potential to learn can rationalize such bans. The model is calibrated to a representative municipality in Colorado, the site of several fracking bans. With plausible damages, we find that the QOV increases the incentive to delay drilling within a range of energy prices. The results suggest that improving the ability to learn about fracking impacts could increase the prevalence of bans in the short run and lead to better policymaking over time. Incorporating CGE output into a dynamic learning framework permits calculation of the locality-wide QOV associated with a range of policies.
Inverse design of near unity efficiency perfectly vertical grating couplers

Efficient coupling between integrated optical waveguides and optical fibers is essential to the success of silicon photonics. While many solutions exist, perfectly vertical grating couplers that scatter light out of a waveguide in the direction normal to the waveguide's top surface are an ideal candidate due to their potential to reduce packaging complexity. Designing such couplers with high efficiencies, however, has proven difficult. In this paper, we use inverse electromagnetic design techniques to optimize a high efficiency two-layer perfectly vertical silicon grating coupler. Our base design achieves a chip-to-fiber coupling efficiency of 99.2% (-0.035 dB) at 1550 nm. Using this base design as a starting point, we run subsequent constrained optimizations to realize vertical couplers with coupling efficiencies over 96% and back reflections of less than -40 dB which can be fabricated using 65 nm-resolution lithography. These results demonstrate a new path forward for designing fabrication-tolerant ultra high efficiency grating couplers.
Effective out-of-core parallel delaunay mesh refinement using off-the-shelf software

We present three related out-of-core parallel mesh generation algorithms and their implementations for small size computational clusters. Computing out-of-core permits to solve larger problems than otherwise possible on the same hardware setup. Also, when using shared computing resources with high demand, a problem can take longer to compute in terms of wall-clock time when using an in-core algorithm on many nodes instead of using an out-of-core algorithm on few nodes. The difference is due to wait-in-queue delays that can grow exponentially to the number of requested nodes. In one specific case, using our best method and only 16 nodes it can take several times less wall-clock time to generate a 2 billion element mesh than to generate the same size mesh in-core with 121 nodes.Although our best out-of-core method exhibits unavoidable overheads (could be as low as 19p in some cases) over the corresponding in-core method (for mesh sizes that fit completely in-core), this is a modest and expected performance penalty. We evaluated our methods on traditional clusters of workstations as well as presented preliminary performance evaluation on emerging BlueWaters supercomputer.
Bridging Properties of Multiblock Copolymers

Using self-consistent field theory, we attempt to elucidate the links between microscopically determined properties, such as the bridging fraction of chains, and mechanical properties of multiblock copolymer materials. We determine morphological aspects such as period and interfacial width and calculate the bridging fractions, and compare with experimental data.
Feasibility of Parallelization of Nonlinear Feedback Method of Robot ARM Control

Abstract Computation of Robot model is expensive. Most model-based schemes use a reduced dynamic model and customized programming techniques to achieve good tracking performance. This cannot be done in general. Strong coupling and nonlinearities are a major concern in high speed applications and do not permit large scale model reductions. In order to satisfactorily implement model intensive schemes, fast computation is neccessary. In this paper we discuss the computational aspects of the Nonlinear Feedback Control scheme with task space servo. It fits into recursive computational schemes and a computational overlay using these schemes is developed. Simulation studies, for a PUMA 560 robot model, of the trajectory tracking performance using these recursive computational schemes is presented. These recursive schemes are amenable to parallelization. A distributed computing architecture using this computational overlay for coordinated control of multirobot systems is proposed.
Electro-optical frequency division and stable microwave synthesis

A new method of optical frequency division is demonstrated using a tunable electrical oscillator to create combs through phase modulation of a dual Brillouin laser frequency reference. The method is used to generate stable microwaves.
Toward Establishing a Standard Symptom Set for Assessing Sluggish Cognitive Tempo in Children: Evidence From Teacher Ratings in a Community Sample:

Despite increasing interest in sluggish cognitive tempo (SCT) in children, the field is stymied by the lack of a standard symptom set that can be used across studies. Without a standard symptom set...
ENGINEERING-ECONOMIC SYSTEMS: A PROBLEM-SOLVING DISCIPLINE

Abstract Engineering-Economic Systems represents a discipline that has an engineering, or problem-solving, orientation, but which encompasses application areas beyond those traditionally considered part of engineering. Applications include control engineering, energy policy analysis, urban service planning, medical decision making, investment strategy development, business analysis, algorithm design, as well as subtopics in all other branches of engineering. The discipline is based on a set of fundamental core concepts: dynamics, probability, optimization, economics, and decision analysis; these provide a framework for structuring and solving complex system problems in the same way that physical science forms the foundation for physical branches of engineering. The Department of Engineering-Economic Systems, Stanford University, was established to help create this discipline, through education, research, and involvement in applications. In the twenty years since its creation, the Department has pioneered the concept of broad analytical problem-solving as a discipline, and has evolved strong programs in systems engineering, public policy analysis, and business analysis a wide spectrum of areas cemented together by the foundation of core concepts and a commitment to apply these concepts wherever important issues arise
The Role of Hospital and Market Characteristics in Invasive Cardiac Service Diffusion

Little is known about how the adoption and diffusion of medical innovation is related to and influenced by market characteristics such as competition. The particular complications that are involved in investigating these relationships in the health care sector may explain the dearth of research. We examine three invasive cardiac services: diagnostic angiography, percutaneous coronary interventions, and coronary artery bypass grafting. We document the relationship between the adoption by hospitals of these three invasive cardiac services and the characteristics of the hospitals, their markets, and the interactions among them, from 1997 to 2014. The results show that the probability of hospitals’ adopting a new cardiac service depends on competition in two distinct ways: (1) hospitals are substantially more likely to adopt an invasive cardiac service if competitor hospitals also adopt new services; and (2) hospitals are less likely to adopt a new service if a larger fraction of the nearby population already has geographic access to the service at a nearby hospital. The first effect is stronger, leading to the net effect that hospitals duplicate rather than expand access to care. In addition, for-profit hospitals are considerably more likely to adopt these cardiac services than are either nonprofit or government-owned hospitals. Nonprofit hospitals in high-penetration, for-profit markets are also more likely to adopt them relative to other nonprofits. These results suggest that factors other than medical need—such as a medical arms race—partially explain technological adoption.
The Role of the Human Tumor Stem Cell Assay in Medical Oncology

• The human tumor stem cell assay is a technique that allows in vitro sensitivity testing of antineoplastic agents against cells from tumor specimens removed from patients. This assay predicts clinical response to drugs and permits Individualization of chemotherapy. It is more accurate in predicting drug resistance than drug sensitivity. Although there are technical problems with the assay, it has been successfully applied to nearly every possible type of human solid tumor and can be performed using cells from malignant effusions as well. Screening of new agents for activity against a range of human tumor specimens may prove to be the most important application of the human tumor stem cell assay. ( Arch Intern Med 1983;143:111-114)
Approaching the Controversies in Antibacterial Management of Cancer Patients

The principles for management of infectious complications in cancer patients are continuing to evolve. The critical element includes the prompt institution of broad-spectrum antibiotic(s) empirically when granulocytopenic patients become febrile and continuation and modification of the regimen in patients with persistent fever and granulocytopenia. The view is presented that antibiotics provide systemic prophylaxis as well as therapy in persistently granulocytopenic patients and that they should be continued until all signs of infection have cleared or the granulocyte count has recovered. Such aggressive therapy, supplemented by continued evaluation and monitoring of the patient, can significantly reduce infection-relation morbidity and mortality.
On unique decoding from insertion errors

For any code, the set of received words generated by insertion errors is infinitely large. We prove that infinitely many of these words are uniquely decodable. We proceed to analyze how often unique decoding from insertions occurs for arbitrary codes. These questions are relevant because insertion errors frequently occur in synchronization and DNA, a medium which is beginning to be used for long term data storage. For a codeword c of length n, we are interested in two particular measures. The first is the probability of unique decoding when t insertions occur, if each distinct length n + t received word is output with equal probability. The second is the probability of unique decoding when t sequential insertions occur, and each insertion position and element are selected uniformly at random. This paper attempts to better understand the behavior of the measures for arbitrary codewords, placing a particular emphasis on limiting behavior as t or n increases. Our most substantial contribution is the derivation of upper bounds on both measures, which are mathematically related to Levenshtein's reconstruction problem.
Principles for Possibilia

It seems to be an obvious truth that(1) There could be something that doesn't actually exist.That is, it seems to be obiously true that(1a) ◊∃×(Actually ∼ (× exists)).It is sufficient for the truth of (1) that there could be more people, or trees, or cars, than there actually are. It is also sufficient for the truth of (1) that there could be some pepole, or trees, or cars that are distinct from all those that actually exist. Do (1) and suchlike statements involve a commitment to possibilia, to things that possibly exist, but do not actually exist? If not, why not? And if so, what is the nature of the possibilia to which (1) and its ilk commit us? These simple little questions are at the tip of an iceberg.
Functional Dissection of the Pol V Largest Subunit CTD in RNA-Directed DNA Methylation.

Summary Plant multisubunit RNA polymerase V (Pol V) transcription recruits Argonaute-small interfering RNA (siRNA) complexes that specify sites of RNA-directed DNA methylation (RdDM) for gene silencing. Pol V's largest subunit, NRPE1, evolved from the largest subunit of Pol II but has a distinctive C-terminal domain (CTD). We show that the Pol V CTD is dispensable for catalytic activity in vitro yet essential in vivo. One CTD subdomain (DeCL) is required for Pol V function at virtually all loci. Other CTD subdomains have locus-specific effects. In a yeast two-hybrid screen, the 3′→ 5′ exoribonuclease RRP6L1 was identified as an interactor with the DeCL and glutamine-serine (QS)-rich subdomains located downstream of an Argonaute-binding subdomain. Experimental evidence indicates that RRP6L1 trims the 3′ ends of Pol V transcripts sliced by Argonaute 4 (AGO4), suggesting a model whereby the CTD enables the spatial and temporal coordination of AGO4 and RRP6L1 RNA processing activities.
Multivariable Compensator Design Using Bode Diagrams and Nichols Charts

Abstract In this paper the basic concepts associated with the Multivariable Nyquist Array (MNA) methods are extended to the log-magnitude/frequency and phase-angle/frequency planes. The resulting multivariable Bode diagrams (MBD) are subsequently presented in the log-magnitude/phase angle plane as characterized by the familiar Nichols Chart. A closed loop compensator design procedure is then presented using an interactive graphics facility. An example is provided to demonstrate the utility of the proposed method in the design of dynamic feedback compensators.
How much do online consumers really value free product returns? Evidence from eBay

Abstract Consumer return rates have been steadily rising in recent years, resulting in growing costs for retailers who must manage the returns process and the disposition of returned products. This cost pressure is driven in part by extremely generous return policies, such as giving consumers a full refund upon return. Interestingly, this common retail practice of full refunds is inconsistent with the recommendations of many analytical models of returns, which nearly always show that a partial refund is optimal. Such inconsistencies between theory and practice might arise when the decision drivers included in the analytical models do not match the decision drivers in practice. It might also be the case that retailers are overly optimistic about the value that consumers assign to a full refund, and thus assume that the value of such a policy outweighs its costs. In this paper, we use data collected from eBay, where identical products are sold with different return policies, to investigate these open questions in the literature. We analyze both the return policy drivers from the retailer's perspective and the return policy value from the consumer's perspective. Our results suggest that the value of a full refund policy to consumers may not be as large as one might expect, and it also exhibits a large heterogeneity across buyers with different levels of online purchase experience. In addition, we provide empirical evidence for what has long been suspected by online retailers – that a non-refundable forward shipping charge quickly erodes any value that consumers assign to return policies. The generality of our results is limited by the fact that eBay differs from traditional retail contexts in many respects, including the fact that eBay buyers may not be representative of the general buyer population. However, our study of how eBay consumers value free returns provides new insights into an understudied area, and it can serve as a starting point for future studies of the value of return policies in other retail contexts.
Impact of local transmission congestion on energy storage arbitrage opportunities

Reduced installation and operating costs give energy storage systems an opportunity to participate actively and profitably in electricity markets. In addition to providing ancillary services, energy storage systems can also arbitrage temporal price differences. Congestion in the transmission network often accentuates these price differences and will under certain circumstances enhance the profitability of arbitrage. On the other hand, congestion may also limit the ability of a given storage device to take advantage of arbitrage opportunities.
The Decision to Concentrate: Active Management, Manager Skill, and Portfolio Size

Recent research shows that more highly concentrated portfolios produce superior risk-adjusted returns. The untested premise is that it is the most skillful managers who hold the most concentrated portfolios. In this article, the authors formally examine the implicit assertion that the initial portfolio concentration decision is related to a manager’s inherent investment skill. First, they present a theoretical model indicating that the greater the manager’s skill level, the more concentrated the portfolio should be. Second, they conduct a simulation analysis of the capacity to make accurate ex ante security return forecasts; they show that skilled managers would select as few as 5% of the available securities and that the portfolio concentration decision is directly proportional to investment prowess. Finally, they provide an empirical examination of the actual skill–concentration relationship for actively managed equity mutual funds over 2002–2015 and document that managers who demonstrated past skill do form portfolios with higher concentration levels. The authors conclude that talented asset managers should and actually do hold more concentrated portfolios and that the extent of this concentration decision is meaningfully related to forecasting skill. TOPICS:Manager selection, mutual fund performance, equity portfolio management Key Findings • The authors analyze the level of skill that an active manager must have to justify the decision to form a concentrated set of security holdings rather than a broadly diversified portfolio. • Using a conceptual model and a simulation, they establish a strong direct connection between a manager’s forecasting talent and the portfolio concentration decision. Optimal portfolio sizes decline to as little as 5% of the investable universe with increasing skill. • The authors develop three portfolio concentration measures and demonstrate with an extensive set of historical mutual fund returns that managers with the best past performance do indeed hold the most concentrated portfolios over time.