bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Inlet Structures on the Performance of Oil Supply System of a Variable Speed Rotary Compressor
Authors: Zhu Yihao , He Guogeng , Sun Wei , Shimoji Mihoko , Chen Xiaoxia
Published: March 2019

Variable speed rotary compressors are now increasingly favored in the market of household air-conditioners in China due to its advantage of energy saving and system stability. Oil supply system plays a pivotal role in high efficiency and good reliability of a variable speed rotary compressor. This paper presents an investigation of the effect of inlet structures on the performance of oil supply system of a variable speed rotary compressor by means of numerical simulation and experiment. The method of volume of fluid (VOF) has been employed in the simulation model and a novel experimental test rig is designed to perform oil flow rate measurements in order to validate the simulated results. With the help of numerical simulation, oil flow patterns in oil pump can be visualized and oil supply rate under different working conditions can be predicted. Good agreement between the simulated oil flow rates and the experimental data has been achieved. The results indicate that oil supply rate increases with an increase in oil level height, oil viscosity as well as the rotating speed. Vertical oil suction pipe with a tapered port contributes to oil pumping in comparison with a straight suction pipe and no suction pipe. Additionally, the minimum rotational speed at which oil starts to flow out of the oil pump increases with the oil inlet diameter and the increment of oil inlet diameter allows the improvement oil pumping performance at a high rotating speed.
Flow Dynamics of a Film Cooling Jet Issued From a Round Hole Embedded in Contoured Crater
Authors: Kalghatgi Prasad , Acharya Sumanta
Published: March 2019

Recent advances in gas turbine film cooling technology such as round film cooling holes embedded in craters or trenches, and shaped film cooling holes are of interest due to a marked improvement in the effectiveness of film cooling jets. Typically, shaped film cooling holes have higher manufacturing cost, while film cooling holes embedded in craters/trenches etched in thermal barrier coatings (TBC) are seen as a cost-effective alternative. In a recent numerical study Kalghatgi and Acharya (2015, “Improved Film Cooling Effectiveness With a Round Film Cooling Hole Embedded in Contoured Crater,” ASME J. Turbomach., 137(10), p. 101006) reported a novel crater shape to generate anti-counter rotating vortex pair (CRVP) beneath the film cooling jet and showed a significant improvement in film cooling performance. In the present paper, a comprehensive study of flow dynamics is presented to gain insight into the unsteady flow physics of film cooling jet issued from a round hole embedded in the contoured crater. As a baseline case, a round film cooling hole with a 35 deg inclined short delivery tube (l/D = 1.75) is used as from a previous study with freestream Reynolds number based on jet diameter set to ReD = 16,000 and density ratio of coolant to freestream fluid of ρj/ρo = 2.0. These flow conditions are used for the cases of film cooling jet embedded in contoured crater. The results are presented for two crater depths: (i) shallow crater with 0.2D depth and (ii) deep crater with 0.75D depth. First- and second-order flow statistics are presented for all the cases, including the experimental data for baseline case from the literature. Time-averaged and instantaneous flow structures are visualized to reveal the mechanisms of anti-CRVP and attenuating CRVP. The dynamics of flow structures studied using single-point spectral analysis in the shear layer and modal analysis of three-dimensional flow field shows a loss of coherency and increased time scales of shear layer structures as the crater depth is increased, primarily due to attenuating of CRVP in the downstream vicinity of the crater. The modal analysis confirmed reduced magnitude of temperature fluctuations (hot spots) on the cooling wall compared with baseline round film cooling hole. Finally, a 2–5% additional pressure loss due to the crater is reported over the existing ≈7% loss in pressure for baseline case.
Validation and Stabilization of a Prophage Lysin of Clostridium perfringens by Using Yeast Surface Display and Coevolutionary Models
Authors: Ritter Seth C. , Hackel Benjamin J.
Published: March 2019

Bacteriophage lysins exhibit high specificity and activity toward host bacteria with which the phage coevolved. These properties of lysins make them attractive for use as antimicrobials. Although there has been significant effort to develop platforms for rapid lysin engineering, there have been numerous shortcomings when pursuing the ultrahigh throughput necessary for the discovery of rare combinations of mutations to improve performance. In addition to validation of a putative lysin and stabilization thereof, the experimental and computational methods presented here offer a new avenue for improving protein stability and are easily scalable to analysis of tens of millions of mutations in single experiments.
Disruption of the Putative Ribosome-Binding Motif of a Scaffold Protein Impairs CytochromecOxidase Subunit Expression inLeishmania major
Authors: Cardenas Daviel , Sylvester Charity , Cao Bo , Nation Catherine S. , Pizarro Juan C. , Lu Hua , Guidry Jessie , Wojcik Edward J. , Kelly Ben L.
Published: March 2019

Leishmaniaparasites are trypanosomatid protozoans that persist in infected human hosts to cause a spectrum of pathologies, from cutaneous and mucocutaneous manifestations to visceral leishmaniasis caused byLeishmania donovani. The latter is usually fatal if not treated. Persistence ofL. majorin the mammalian host depends upon maintaining gene-regulatory programs to support essential parasite metabolic functions. These include expression and assembly of mitochondrialL. majorcytochromecoxidase (LmCOX) subunits, important forLeishmaniaATP production. Significantly, under mammalian conditions, WT levels of LmCOX subunits require threshold levels of theLeishmaniaribosome-associated scaffold protein, LACK. Unexpectedly, we find that although disruption of LACK’s putative ribosome-binding motif does not grossly perturb ribosome association or global protein synthesis, it nonetheless impairs COX subunit expression, mitochondrial function, and virulence. Our data indicate that the quality of LACK’s interaction withLeishmaniaribosomes is critical for LmCOX subunit expression and parasite mitochondrial function in the mammalian host. Collectively, these findings validate LACK’s ribosomal interactions as a potential therapeutic target.
StraboSpot data system for structural geology
Authors: Walker J. Douglas , Tikoff Basil , Newman Julie , Clark Ryan , Ash Jason , Good Jessica , Bunse Emily G. , Möller Andreas , Kahn Maureen , Williams Randolph T. , Michels Zachary , Andrew Joseph E. , Rufledt Carson
Published: March 2019

StraboSpot is a geologic data system that allows researchers to digitally collect, store, and share both field and laboratory data. StraboSpot is based on how geologists actually work to collect field data; although initially developed for the structural geology research community, the approach is easily extensible to other disciplines. The data system uses two main concepts to organize data: spots and tags. A spot is any observation that characterizes a specific area, a concept applicable at any spatial scale from regional to microscopic. Spots are related in a purely spatial manner, and consequently, one spot can enclose multiple other spots that themselves contain other spots. In contrast, tags provide conceptual grouping of spots, allowing linkages between spots that are independent of their spatial position.

The StraboSpot data system uses a graph database, rather than a relational database approach, to increase flexibility and to track geologically complex relationships. StraboSpot operates on two different platform types: (1) a field-based application that runs on iOS and Android mobile devices, which can function in either Internet-connected or disconnected environments; and (2) a web application that runs only in Internet-connected settings. We are presently engaged in incorporating microstructural data into StraboSpot, as well as expanding to include additional field-based (sedimentology, petrology) and lab-based (experimental rock deformation) data. The StraboSpot database will be linked to other existing and future databases in order to provide integration with other digital efforts in the geological sciences and allow researchers to do types of science that were not possible without easy access to digital data.
Shape of Training Review: an impact assessment for UK gastroenterology trainees
Authors: Clough Jennifer , FitzPatrick Michael , Harvey Philip , Morris Liam
Published: March 2019

Background

Physician training in the UK is undergoing considerable change due to the implementation of recommendations made in the Shape of Training Review. In particular, higher specialty training (HST), including gastroenterology, will be shortened from 5 to 4 years. This will also incorporate general internal medicine (GIM) training. There is concern among gastroenterologists regarding how high-quality gastroenterology training will be delivered in 4 years.

Methods

The 2018 British Society of Gastroenterology (BSG) trainees’ survey results were used to examine the potential impact of a 4-year HST period on achieving key competencies in gastroenterology.

Results

291 (49.4%) gastroenterology trainees responded. Satisfaction with gastroenterology training was high (79.6% respondents), and self-reported confidence in hepatology training was also high (84% senior respondents). However, only half (51.1%) of the respondents achieved complete colonoscopy certification by their final year of training. Comparison with the 2014 BSG trainees’ survey demonstrated that the number of endoscopy procedures achieved by trainees has reduced in sigmoidoscopy (p=0.006) and colonoscopy (p<0.001). The proportion of time spent in GIM training has increased since the last survey, with 81.8% of the respondents spending more than 25% of their time in GIM. GIM training was reported to be a key barrier to adequate gastroenterology and endoscopy training.

Conclusion

These data indicate significant barriers to delivering gastroenterology and endoscopy training within the current 5-year programme. Novel strategies will be required to improve the rate of progression in endoscopy training, in particular if high-quality gastroenterology HST training is to be delivered in 4 years.
Impacts of helmet law on the changes in potential years of life lost due to traffic injury: a multiple-province evaluation in Vietnam
Authors: Phung Dung , Nguyen Ha Trong , Chu Cordia , Sadler Ross , Luong Anh Mai , Nguyen Huyen Thi , Pham Tuan Cong , Huang Cunrui
Published: March 2019

Introduction

This study aimed to evaluate the impact of the helmet law on the changes in potential years of life lost (PYLL) due to traffic mortality and to examine modification effects of socioeconomic factors on the impacts in Vietnam.

Methods

We applied an interrupted time series design using the Bayesian framework to estimate the impact of the law at the provincial level. Then, we used random effects meta-analysis to estimate the impact of the law at the country level and to examine the modification effects of socioeconomic factors.

Results

The results indicate that the impacts varied among the provinces. These impacts could be classified by four main groups comprising positive impact, and positive impact without sustainability, possible positive impact, negative or inconsistent impact. For the country-level impact, the results reveal a significantly consistent change in monthly PYLLs at the level of 18 per 100 000 persons, and the post-trend was stable without significant change. The results of meta-regression show that 1 unit increase in the population density (persons/km2), migration rate (%) and income (×1000 dong) are non-significantly associated with increases of PYLLs at 1.3, 27 and 27 per 100 000 person-months, respectively, whereas 1% increase in literacy associated with a decrease of PYLL at 44 per 100 000 person-months.

Discussion

Further studies should be warranted to provide a comprehensive evaluation of the law implementation, including its acceptability, adoption, appropriateness, feasibility, cost-effectiveness and sustainability.
CO466 corn inbred line
Authors: Reid L.M. , Zhu X. , Wu J. , Voloaca C. , Woldemariam T. , Jindal K.K.
Published: March 2019

CO466 is a short-season corn (Zea mays L.) inbred line with excellent combining ability with both Iodent and stiff stalk inbred testers, and the early maturing AAFC line CL30. CO466 has moderate resistance to eyespot, Goss’s bacterial wilt, grey leaf spot, common rust, and fusarium stalk rot.
A Pumping Lemma for Permitting Semi-Conditional Languages
Authors: Gazdag Zsolt , Tichler Krisztián , Csuhaj-Varjú Erzsébet
Published: March 2019

Permitting semi-conditional grammars (pSCGs) are extensions of context-free grammars where each rule is associated with a word [Formula: see text] and such a rule can be applied to a sentential form [Formula: see text] only if [Formula: see text] is a subword of [Formula: see text]. We consider permitting generalized SCGs (pgSCGs) where each rule [Formula: see text] is associated with a set of words [Formula: see text] and [Formula: see text] is applicable only if every word in [Formula: see text] occurs in [Formula: see text]. We investigate the generative power of pgSCGs with no erasing rules and prove a pumping lemma for their languages. Using this lemma we show that pgSCGs are strictly weaker than context-sensitive grammars. This solves a long-lasting open problem concerning the generative power of pSCGs. Moreover, we give a comparison of the generating power of pgSCGs and that of forbidding random context grammars with no erasing rules.
On the Interplay Between Černý and Babai’s Conjectures
Authors: Gonze François , Gusev Vladimir V. , Jungers Raphaël M. , Gerencsér Balázs , Volkov Mikhail V.
Published: March 2019

Motivated by the Babai conjecture and the Černý conjecture, we study the reset thresholds of automata with the transition monoid equal to the full monoid of transformations of the state set. For automata with [Formula: see text] states in this class, we prove that the reset threshold is upper-bounded by [Formula: see text] and can attain the value [Formula: see text]. In addition, we study diameters of the pair digraphs of permutation automata and construct [Formula: see text]-state permutation automata with diameter [Formula: see text].
Protective Effects of Ligustroflavone, an Active Compound from Ligustrum lucidum, on Diabetes-Induced Osteoporosis in Mice: A Potential Candidate as Calcium-Sensing Receptor Antagonist
Authors: Feng Rui , Ding Fan , Mi Xiu-Hua , Liu Shu-Fen , Jiang Ai-Ling , Liu Bi-Hui , Lian Yin , Shi Qi , Wang Yong-Jun , Zhang Yan
Published: March 2019

Ligustroflavone is one major compound contained in active fraction from Fructus Ligustri Lucidi (the fruit of Ligustrum lucidum), which could regulate parathyroid hormone (PTH) levels and improve calcium balance by acting on calcium-sensing receptors (CaSR). This study aimed to explore the potency of ligustroflavone as a CaSR antagonist and its protective effects against diabetic osteoporosis in mice. LF interacted well with the allosteric site of CaSR shown by molecular docking analysis, increased PTH release of primary parathyroid gland cells and suppressed extracellular calcium influx in HEK-293 cells. The serum level of PTH attained peak value at 2[Formula: see text]h and maintained high during the period of 1[Formula: see text]h and 3[Formula: see text]h than that before treatment in mice after a single dose of LF. Treatment of diabetic mice with LF inhibited the decrease in calcium level of serum and bone and the enhancement in urinary calcium excretion as well as elevated circulating PTH levels. Trabecular bone mineral density and micro-architecture were markedly improved in diabetic mice upon to LF treatment for 8 weeks. LF reduced CaSR mRNA and protein expression in the kidneys of diabetic mice. Taken together, ligustroflavone could transiently increase PTH level and regulate calcium metabolism as well as prevent osteoporosis in diabetic mice, suggesting that ligustroflavone might be an effective antagonist on CaSR.
Higher order multipoint flux mixed finite element methods on quadrilaterals and hexahedra
Authors: Ambartsumyan Ilona , Khattatov Eldar , Lee Jeonghun J. , Yotov Ivan
Published: March 2019

We develop higher order multipoint flux mixed finite element (MFMFE) methods for solving elliptic problems on quadrilateral and hexahedral grids that reduce to cell-based pressure systems. The methods are based on a new family of mixed finite elements, which are enhanced Raviart–Thomas spaces with bubbles that are curls of specially chosen polynomials. The velocity degrees of freedom of the new spaces can be associated with the points of tensor-product Gauss–Lobatto quadrature rules, which allows for local velocity elimination and leads to a symmetric and positive definite cell-based system for the pressures. We prove optimal [Formula: see text]th order convergence for the velocity and pressure in their natural norms, as well as [Formula: see text]st order superconvergence for the pressure at the Gauss points. Moreover, local postprocessing gives a pressure that is superconvergent of order [Formula: see text] in the full [Formula: see text]-norm. Numerical results illustrating the validity of our theoretical results are included.
Visco-energetic solutions to some rate-independent systems in damage, delamination, and plasticity
Authors: Rossi Riccarda
Published: March 2019

This paper revolves around a newly introduced weak solvability concept for rate-independent systems, alternative to the notions of Energetic ([Formula: see text]) and Balanced Viscosity ([Formula: see text]) solutions. Visco-Energetic ([Formula: see text]) solutions have been recently obtained by passing to the time-continuous limit in a time-incremental scheme, akin to that for [Formula: see text] solutions, but perturbed by a “viscous” correction term, as in the case of [Formula: see text] solutions. However, for VE solutions this viscous correction is tuned by a fixed parameter. The resulting solution notion turns out to describe a kind of evolution in between Energetic and BV evolution. In this paper we aim to investigate the application of [Formula: see text] solutions to nonsmooth rate-independent processes in solid mechanics such as damage and plasticity at finite strains. We also address the limit passage, in the [Formula: see text] formulation, from an adhesive contact to a brittle delamination system. The analysis of these applications reveals the wide applicability of this solution concept, in particular to processes for which [Formula: see text] solutions are not available, and confirms its intermediate character between the [Formula: see text] and [Formula: see text] notions.
Sharp error estimates for spline approximation: Explicit constants, n-widths, and eigenfunction convergence
Authors: Sande Espen , Manni Carla , Speleers Hendrik
Published: March 2019

In this paper, we provide a priori error estimates in standard Sobolev (semi-)norms for approximation in spline spaces of maximal smoothness on arbitrary grids. The error estimates are expressed in terms of a power of the maximal grid spacing, an appropriate derivative of the function to be approximated, and an explicit constant which is, in many cases, sharp. Some of these error estimates also hold in proper spline subspaces, which additionally enjoy inverse inequalities. Furthermore, we address spline approximation of eigenfunctions of a large class of differential operators, with a particular focus on the special case of periodic splines. The results of this paper can be used to theoretically explain the benefits of spline approximation under [Formula: see text]-refinement by isogeometric discretization methods. They also form a theoretical foundation for the outperformance of smooth spline discretizations of eigenvalue problems that has been numerically observed in the literature, and for optimality of geometric multigrid solvers in the isogeometric analysis context.
Lévy differential operators and Gauge invariant equations for Dirac and Higgs fields
Authors: Volkov Boris O.
Published: March 2019

We study the Lévy infinite-dimensional differential operators (differential operators defined by the analogy with the Lévy Laplacian) and their relationship to the Yang–Mills equations. We consider the parallel transport on the space of curves as an infinite-dimensional analogue of chiral fields and show that it is a solution to the system of differential equations if and only if the associated connection is a solution to the Yang–Mills equations. This system is an analogue of the equations of motion of chiral fields and contains the Lévy divergence. The systems of infinite-dimensional equations containing Lévy differential operators, that are equivalent to the Yang–Mills–Higgs equations and the Yang–Mills–Dirac equations (the equations of quantum chromodynamics), are obtained. The equivalence of two ways to define Lévy differential operators is shown.
Nonlinear Dynamics of a Fluid–Structure Coupling Model for Vortex-Induced Vibration
Authors: Chen Jie , Li Qiu-Sheng
Published: March 2019

This paper presents a fluid–structure coupling model to investigate the vortex-induced vibration of a circular cylinder subjected to a uniform cross-flow. A modified van der Pol nonlinear equation is employed to represent the fluctuating nature of vortex shedding. The wake oscillator is coupled with the motion equation of the cylinder by applying coupling terms in modeling the fluid–structure interaction. The transient responses of the fluid–structure coupled model are presented and discussed by numerical simulations. The results demonstrate the main features of the vortex-induced vibration, such as lock-in phenomenon, i.e. resonant oscillation of the cylinder occurs when the vortex shedding frequency is near to the natural frequency of the cylinder. The resonant responses of the fluid–structure coupled model in the lock-in region are determined by the multiple scales method. The accuracy of the asymptotic solution by the multiple scales method is verified by comparing with the numerical solution from the motion equation. The effects of different parameters on the steady state amplitude of oscillation are investigated for a given set of parameters. Frequency–response curves obtained from the modulation equation demonstrate the existence of jump phenomena.
Computational studies, NMR, Raman and infrared spectral analysis of centrosymmetric (2Z,4Z)-Hexa-2,4-dienedinitrile
Authors: Mohamed Tarek A. , Shaaban Ibrahim A. , Soliman Usama A. , Zoghaib Wajdi M.
Published: March 2019

The Raman (50–3500[Formula: see text]cm[Formula: see text]) and infrared (200–3500[Formula: see text]cm[Formula: see text]) spectra of (2Z,4Z)-Hexa-2,4-dienedinitrile (C6H4N2; cis,cis-HDDN) have been recorded. Initially, three conformers were proposed based on following point groups: C2h, C2v and [Formula: see text] (gauche). For comparison purposes, M05-2X, M06-2X method were used in addition to B3LYP, MP2[Formula: see text]full and MP4[Formula: see text]full quantum mechanical calculations employing 6-31G(d) and 6-311+G(d,p) basis sets using Gaussian 09 program. Aided by potential energy surface scan, the C2h conformer is verified as a global minimum and the gauche ([Formula: see text]) being a local minimum with an energy barrier of 2.82[Formula: see text]kcal/mol. The energy difference ranged from 4.87 to 13.70[Formula: see text]kcal/mol favors the C2h conformer in good agreement with Raman and infrared spectral analysis. These results were also supported by the observed [Formula: see text] value (H9-H[Formula: see text]) at 10.8[Formula: see text]Hz which is consistent to 10.19[Formula: see text]Hz estimated for centrosymmetric conformer (C2h) rather than 4.81[Formula: see text]Hz predicted for gauche ([Formula: see text]). Complete vibrational assignments are proposed herein based on normal coordinate analysis (NCA) and potential energy distributions (PEDs) combined with theoretical vibrational frequencies and force constants in internal coordinates. It is crucial that NCA using VEDA 4 program with mixing shows large deviations from ours due to neglecting symmetry elements while mixing molecular vibrational motions. The results of these spectroscopic and theoretical studies are reported herein and compared with similar molecules whenever appropriate.
Almost Ricci solitons isometric to spheres
Authors: Deshmukh Sharief
Published: March 2019

We find a characterization of a sphere using a compact gradient almost Ricci soliton and the lower bound on the integral of Ricci curvature in the direction of potential field. Also, we use Poisson equation on a compact gradient almost Ricci soliton to find a characterization of the unit sphere.
Juggler
Authors: Belviranli Mehmet E. , Lee Seyong , Vetter Jeffrey S. , Bhuyan Laxmi N.
Published: March 2019

Scientific applications with single instruction, multiple data (SIMD) computations show considerable performance improvements when run on today's graphics processing units (GPUs). However, the existence of data dependences across thread blocks may significantly impact the speedup by requiring global synchronization across multiprocessors (SMs) inside the GPU. To efficiently run applications with interblock data dependences, we need fine-granular task-based execution models that will treat SMs inside a GPU as stand-alone parallel processing units. Such a scheme will enable faster execution by utilizing all internal computation elements inside the GPU and eliminating unnecessary waits during device-wide global barriers.

In this paper, we propose
Juggler
, a task-based execution scheme for GPU workloads with data dependences. The Juggler framework takes applications embedding OpenMP 4.5 tasks as input and executes them on the GPU via an efficient in-device runtime, hence eliminating the need for kernel-wide global synchronization. Juggler requires no or little modification to the source code, and once launched, the runtime entirely runs on the GPU without relying on the host through the entire execution. We have evaluated Juggler on an NVIDIA Tesla P100 GPU and obtained up to 31% performance improvement against global barrier based implementation, with minimal runtime overhead.
vS
ensor
Authors: Tang Xiongchao , Zhai Jidong , Qian Xuehai , He Bingsheng , Xue Wei , Chen Wenguang
Published: March 2019

Performance variance becomes increasingly challenging on current large-scale HPC systems. Even using a fixed number of computing nodes, the execution time of several runs can vary significantly. Many parallel programs executing on supercomputers suffer from such variance. Performance variance not only causes unpredictable performance requirement violations, but also makes it unintuitive to understand the program behavior. Despite prior efforts, efficient on-line detection of performance variance remains an open problem.

In this paper, we propose vS
ensor
, a novel approach for light-weight and on-line performance variance detection. The key insight is that, instead of solely relying on an external detector, the source code of a program itself could reveal the runtime performance characteristics. Specifically, many parallel programs contain code snippets that are executed repeatedly with an invariant quantity of work. Based on this observation, we use compiler techniques to automatically identify these fixed-workload snippets and use them as performance variance sensors (v-sensors) that enable effective detection. We evaluate vS
ensor
with a variety of parallel programs on the Tianhe-2 system. Results show that vS
ensor
can effectively detect performance variance on HPC systems. The performance overhead is smaller than 4% with up to 16,384 processes. In particular, with vS
ensor
, we found a bad node with slow memory that slowed a program's performance by 21%. As a showcase, we also detected a severe network performance problem that caused a 3.37X slowdown for an HPC kernel program on the Tianhe-2 system.
Featherlight on-the-fly false-sharing detection
Authors: Chabbi Milind , Wen Shasha , Liu Xu
Published: March 2019

Shared-memory parallel programs routinely suffer from false sharing---a performance degradation caused by different threads accessing different variables that reside on the same CPU cacheline and at least one variable is modified. State-of-the-art tools detect false sharing via a heavyweight process of logging memory accesses and feeding the ensuing access traces to an offline cache simulator. We have developed F
eather
, a lightweight, on-the-fly false-sharing detection tool. F
eather
achieves low overhead by exploiting two hardware features ubiquitous in commodity CPUs: the
performance monitoring units
(PMU) and
debug registers.
Additionally, F
eather
is a first-of-its-kind tool to detect false sharing in multi-process applications that use shared memory. F
eather
allowed us to scale false-sharing detection to myriad codes. F
eather
detected several false-sharing cases in important multi-core and multi-process codes including previous PPoPP artifacts. Eliminating false sharing resulted in dramatic (up to 16x) speedups.
Register optimizations for stencils on GPUs
Authors: Rawat Prashant Singh , Rastello Fabrice , Sukumaran-Rajam Aravind , Pouchet Louis-Noël , Rountev Atanas , Sadayappan P.
Published: March 2019

The recent advent of compute-intensive GPU architecture has allowed application developers to explore high-order 3D stencils for better computational accuracy. A common optimization strategy for such stencils is to expose sufficient data reuse by means such as loop unrolling, with the expectation of register-level reuse. However, the resulting code is often highly constrained by register pressure. While current state-of-the-art register allocators are satisfactory for most applications, they are unable to effectively manage register pressure for such complex high-order stencils, resulting in sub-optimal code with a large number of register spills. In this paper, we develop a statement reordering framework that models stencil computations as a DAG of trees with shared leaves, and adapts an optimal scheduling algorithm for minimizing register usage for expression trees. The effectiveness of the approach is demonstrated through experimental results on a range of stencils extracted from application codes.
Safe privatization in transactional memory
Authors: Khyzha Artem , Attiya Hagit , Gotsman Alexey , Rinetzky Noam
Published: March 2019

Transactional memory
(TM) facilitates the development of concurrent applications by letting the programmer designate certain code blocks as atomic. Programmers using a TM often would like to access the same data both inside and outside transactions, e.g., to improve performance or to support legacy code. In this case, programmers would ideally like the TM to guarantee
strong atomicity
, where transactions can be viewed as executing atomically also with respect to non-transactional accesses. Since guaranteeing strong atomicity for arbitrary programs is prohibitively expensive, researchers have suggested guaranteeing it only for certain
data-race free (DRF)
programs, particularly those that follow the
privatization
idiom: from some point on, threads agree that a given object can be accessed non-transactionally. Supporting privatization safely in a TM is nontrivial, because this often requires correctly inserting
transactional fences
, which wait until all active transactions complete.

Unfortunately, there is currently no consensus on a single definition of transactional DRF, in particular, because no existing notion of DRF takes into account transactional fences. In this paper we propose such a notion and prove that, if a TM satisfies a certain condition generalizing opacity and a program using it is DRF
assuming
strong atomicity, then the program indeed has strongly atomic semantics. We show that our DRF notion allows the programmer to use privatization idioms. We also propose a method for proving our generalization of opacity and apply it to the TL2 TM.
Efficient shuffle management with SCache for DAG computing frameworks
Authors: Fu Zhouwang , Song Tao , Qi Zhengwei , Guan Haibing
Published: March 2019

In large-scale data-parallel analytics, shuffle, or the cross-network read and aggregation of partitioned data between tasks with data dependencies, usually brings in large overhead. To reduce shuffle overhead, we present
SCache
, an open source plug-in system that particularly focuses on shuffle optimization. By extracting and analyzing shuffle dependencies prior to the actual task execution, SCache can adopt heuristic pre-scheduling combining with shuffle size prediction to pre-fetch shuffle data and balance load on each node. Meanwhile, SCache takes full advantage of the system memory to accelerate the shuffle process. We have implemented SCache and customized Spark to use it as the external shuffle service and co-scheduler. The performance of SCache is evaluated with both simulations and testbed experiments on a 50-node Amazon EC2 cluster. Those evaluations have demonstrated that, by incorporating SCache, the shuffle overhead of Spark can be reduced by nearly 89%, and the overall completion time of TPC-DS queries improves 40% on average.
Performance challenges in modular parallel programs
Authors: Acar Umut A. , Aksenov Vitaly , Charguéraud Arthur , Rainey Mike
Published: March 2019

Over the past decade, many programming languages and systems for parallel-computing have been developed, including Cilk, Fork/Join Java, Habanero Java, Parallel Haskell, Parallel ML, and X10. Although these systems raise the level of abstraction at which parallel code are written, performance continues to require the programmer to perform extensive optimizations and tuning, often by taking various architectural details into account. One such key optimization is granularity control, which requires the programmer to determine when and how parallel tasks should be sequentialized.

In this paper, we briefly describe some of the challenges associated with automatic granularity control when trying to achieve portable performance for parallel programs with arbitrary nesting of parallel constructs. We consider a result from the functional-programming community, whose starting point is to consider an "oracle" that can predict the work of parallel codes, and thereby control granularity. We discuss the challenges in implementing such an oracle and proving that it has the desired theoretical properties under the nested-parallel programming model.
Reducing the burden of parallel loop schedulers for many-core processors
Authors: Arif Mahwish , Vandierendonck Hans
Published: March 2019

This work proposes a low-overhead half-barrier pattern to schedule fine-grain parallel loops and considers its integration in the Intel OpenMP and Cilkplus schedulers. Experimental evaluation demonstrates that the scheduling overhead of our techniques is 43% lower than Intel OpenMP and 12.1x lower than Cilk. We observe 22% speedup on 48 threads, with a peak of 2.8x speedup.
Strong trylocks for reader-writer locks
Authors: Correia Andreia , Ramalhete Pedro
Published: March 2019

A reader-writer lock provides basic methods for shared and exclusive lock acquisition. A thread calling one of these methods may have to wait indefinitely to enter its critical section, with no guarantee of completion.

We present two new reader-writer
strong
trylock algorithms, where a call to a trylock method always completes in a finite number of steps, and is guaranteed to succeed unless there is a linearizable history for which another thread has the lock. The first algorithm, named StrongTryRW, uses a single word of memory to reach consensus, thus yielding reduced scalability for readers. To address read scalability, we designed StrongTryRWRI which matches in throughput the current state of the art reader-writer lock algorithms.
Register-based implementation of the sparse general matrix-matrix multiplication on GPUs
Authors: Liu Junhong , He Xin , Liu Weifeng , Tan Guangming
Published: March 2019

General sparse matrix-matrix multiplication (SpGEMM) is an essential building block in a number of applications. In our work, we fully utilize GPU registers and shared memory to implement an efficient and load balanced SpGEMM in comparison with the existing implementations.
A microbenchmark to study GPU performance models
Authors: Volkov Vasily
Published: March 2019

Basic microarchitectural features of NVIDIA GPUs have been stable for a decade, and many analytic solutions were proposed to model their performance. We present a way to review, systematize, and evaluate these approaches by using a microbenchmark. In this manner, we produce a brief algebraic summary of key elements of selected performance models, identify patterns in their design, and highlight their previously unknown limitations. Also, we identify a potentially superior method for estimating performance based on classical work.
SIMD code generation for stencils on brick decompositions
Authors: Zhao Tuowen , Hall Mary , Basu Protonu , Williams Samuel , Johansen Hans
Published: March 2019

We present a stencil library and associated compiler code generation framework designed to maximize performance on higher-order stencil computations through the use of two main technologies: a fine-grained
brick
data layout designed to exploit the inherent multidimensional spatial locality endemic to stencil computations, and a
vector scatter
associative reordering transformation that reduces vector loads and alignment operations and exposes opportunities for the backend compiler to reduce computation. For a range of stencil computations, we compare the generated code expressed in the brick library to the standard tiled code. We attain up to a 7.2X speedup on the most complex stencils when running on an Intel Knights Landing (Xeon Phi) processor.
Inequality and Social Stratification in Postsocialist China
Authors: Wu Xiaogang
Published: March 2019

This article reviews research on inequality and social stratification in China since the mid-1990s. Going beyond the theoretical framework of the market transition debate, research in the field has been advanced by paying more attention to the roles of the institutions of Chinese state socialism, such as the household registration ( hukou) and urban work unit ( danwei) systems, and workers’ self-selective mobility. Empirical studies have benefited from the systematic collection of well-designed and high-quality survey data and from the application of advanced statistical methods. Substantive analysis has been extended to new themes related to social class, gender, ethnicity, education, and housing wealth. This review concludes by seeking to identify the wider implications of empirical findings from China for comparative research on inequality and social stratification and by providing some suggestions for the future direction of the field.
Ten maxims of formative assessment
Authors: Prashanti Eachempati , Ramnarayan Komattil
Published: March 2019

In an era that is seemingly saturated with standardized tests of all hues and stripes, it is easy to forget that assessments not only measure the performance of students, but also consolidate and enhance their learning. Assessment for learning is best elucidated as a process by which the assessment information can be used by teachers to modify their teaching strategies while students adjust and alter their learning approaches. Effectively implemented, formative assessments can convert classroom culture to one that resonates with the triumph of learning. In this paper, we present 10 maxims that show ways that formative assessments can be better understood, appreciated, and implemented.
MicroRNA-183 inhibition exerts suppressive effects on diabetic retinopathy by inactivating BTG1-mediated PI3K/Akt/VEGF signaling pathway
Authors: Zhang Zhen-Zhen , Qin Xiu-Hong , Zhang Jing
Published: March 2019

Diabetic retinopathy (DR) is a serious diabetic complication caused by both environmental and genetic factors. Molecular mechanisms of DR may lead to the discovery of reliable prognostic indicators. The current study aimed to clarify the mechanism of microRNA-183 (miR-183) in DR in relation to the PI3K/Akt/VEGF signaling pathway. Microarray-based gene expression profiling of DR was used to identify the differentially expressed genes. Sprague-Dawley rats were used for the establishment of DR models, and then miR-183 was altered by mimic or inhibitor or BTG1 was downregulated by siRNA to explore the regulatory mechanism of miR-183 in DR. Furthermore, the expression of miR-183, CD34, endothelial nitric oxide synthase (eNOS), BTG1 and the PI3K/Akt/VEGF signaling pathway-related genes as well as reactive oxygen species (ROS) level was determined, and the relationship between miR-183 and BTG1 was also verified. Cell growth, cell apoptosis, and angiogenesis were determined. Microarray analysis revealed the involvement of miR-183 in DR via the PI3K/Akt/VEGF signaling pathway by targeting BTG1. Upregulated miR-183 and downregulated BTG1 were observed in retinal tissues of DR rats. miR-183 overexpression activated the PI3K/Akt/VEGF signaling pathway, upregulated CD34, eNOS, and ROS, and inhibited BTG1. BTG1 was confirmed as a target gene of miR-183. miR-183 overexpression or BTG1 knockdown promoted cell growth and tube formation while it suppressed cell apoptosis of vascular endothelial cells in DR rats. In this study, we demonstrated that miR-183 silencing inhibiting cell growth and tube formation in vascular endothelial cells of DR rats via the PI3K/Akt/VEGF signaling pathway by upregulating BTG1.
Extract fromBougainvillea xbuttiana(Variety Orange) Inhibits Production of LPS-Induced Inflammatory Mediators in Macrophages and Exerts a Protective EffectIn Vivo
Authors: Abarca-Vargas Rodolfo , Petricevich Vera L.
Published: March 2019

Background. Different pharmacological properties, such as antioxidant, antiproliferative, and anti-inflammatory properties, have been described among natural products. We previously described that theBougainvillea xbuttiana(Variety Orange) ethanolic extract (BxbO) has an anti-inflammatory effect; however, this action is not fully understood. In this study, the action of the BxbO extract on the secretion of inflammatory mediators in two experimental models,in vitroandin vivo, after LPS challenge was evaluated.Methods. Peritoneal macrophages were obtained from female BALB/c mice and LPS-challenged with or without the BxbO extract. For the evaluation of mediators, the supernatants at 0, 12, 24, 36, and 48 hours were collected. Forin vivoestimation, groups of female BALB/c mice were first intraperitoneously injected with different amounts of LPS and later administered the oral BxbO extract (v.o.) for 144 hours. To understand the mechanism of action, sera obtained from mice were collected at 0, 2, 4, 8, 12, and 24 hours after LPS challenge (with or without BxbO) for the detection of mediators.Results. The results showed that, in both peritoneal macrophages and sera of mice treated with the BxbO extract 1 hour before or together with LPS challenge, proinflammatory cytokines and nitric oxide release were unquestionably repressed. In contrast, in both systems studied here, the IL-10 levels were elevated to 5 to 9 times. At lethal doses of LPS, the BxbO extract treatment was found to protect animals from death.Conclusions. The results revealed that the inhibitory, protective, and benign effects of the BxbO extract were due to its capacity to balance the secretion of mediators.
Suboxone Treatment and Recovery Trial (STAR-T): Study Protocol for a Randomised Controlled Trial of Opioid Medication Assisted Treatment with Adjunctive Medication Management Using Therapeutic Drug Monitoring and Contingency Management
Authors: Elarabi Hesham , Elrasheed Abuelgasim , Ali Ahmed , Shawky Mansour , Hasan Nael , Gawad Tarek A. , Adem Abdu , Marsden John
Published: March 2019

Introduction. Opioid assisted treatment (OAT) with buprenorphine (BUP) is front-line medical maintenance intervention for illicit and prescription opioid use disorder (OUD). In many clinics, opioid medication is dispensed for several days for self-administration. This provides flexibility to the patient but may compromise the effectiveness of OAT because of nonadherence or medication diversion. OAT can be delivered as an entirely supervised intervention, but many patients discontinue treatment under this arrangement and dispensing costs may be prohibitive. An alternative is to enable patients to receive take-home doses contingent on OAT adherence guided by a medication management framework using Therapeutic Drug Monitoring (TDM) alongside negative urine drug screens (UDS) to provide evidence of abstinence. TDM is recommended to monitor adherence with BUP but it has not been applied in OAT programs and evaluation research to date. Methods. The Suboxone Treatment and Recovery Trial (STAR-T) is a single site, 16-week, parallel-group, randomised controlled trial. The aim of the study is to determine the effectiveness of a medication management framework including TDM and UDS to enable patients enrolled on outpatient OAT (with buprenorphine/naloxone [sublingual film formulation; BUP/NX-F; Suboxone™]) to receive stepped take-home doses. Following stabilisation during inpatient care, adult participants with illicit or prescription OUD were allocated (1:1) to receive (1) BUP/NX-F plus medication management for take-home doses based on TDM, UDS, and contingency management protocol (the experimental group) or (2) BUP/NX-F plus UDS only (treatment-as-usual, the control group). The primary outcome is the mean percentage of negative UDS over 16 weeks. The secondary outcome is treatment retention defined as completion of 16 weeks of OAT without interruption. There will be an exploratory analysis of the association between participant characteristics, clinical data, and outcomes. Conclusions. Providing BUP/NX-F take-home doses contingent on adherence and opioid abstinence may enable OAT to be delivered flexibly and effectively. Trial Registration. ISRCTN41645723 is retrospectively registered on 15/11/2015.
Water Sorption and Mechanical Properties of Starch/Chitosan Nanoparticle Films
Authors: Othman Siti H. , Kechik Nurul R. A. , Shapi’i Ruzanna A. , Talib Rosnita A. , Tawakkal Intan S. M. A.
Published: March 2019

The usage of biopolymer as food packaging material has been limited due to high water sorption and poor mechanical properties of the biopolymer. Thus, this study is aimed at improving the water sorption and mechanical properties of biopolymer particularly starch films by incorporation of a natural filler particularly chitosan nanoparticle (CNP) and investigating the properties of starch/CNP films at different storage conditions (relative humidity: 23, 50, and 75%; temperature: 4, 30, and 40°C). The water sorption behavior and isotherms of the films were investigated by fitting the water sorption data to the Peleg model and Guggenheim, Anderson, and de Boer model. Both the models were well fitted to the experimental data, thus proving the reliability of water sorption behavior prediction. It was found that different storage conditions of the films significantly affected the mechanical properties of the films due to the sensitivity of the films towards moisture. Water sorption and mechanical properties of the films were best improved at relative humidity of 23% and temperature of 30°C. The water sorption and mechanical properties of the films are worth to be investigated because the properties affected the stability, shelf life, and application of the films in the food packaging field.