bluuebunny/crossref_metadata_2025 huggingface dataset:
Neighborhood Characteristics and Adolescent Suicidal Behavior: Evidence from a Population‐based Study
Authors: Allen Kristina , Goldman‐Mellor Sidra
Published: September 2017

Research on the relationship between neighborhood characteristics and adolescents’ risk of nonfatal suicidal behavior is scarce. We used California survey data to examine associations between measures of objective neighborhood quality (levels of violent crime, property crime, and socioeconomic disadvantage) and subjective neighborhood quality (perceptions of neighborhood safety and social cohesion) and adolescents’ self‐reported suicidal ideation and suicide attempt. Objective measures of neighborhood quality were unrelated to adolescents’ risk of suicidal behavior. However, adolescents who perceived their neighborhoods to be less safe and less cohesive were 20%–45% more likely than nonsuicidal peers to report suicidal ideation and attempt.
Tangent cones to generalised theta divisors and generic injectivity of the theta map
Authors: Hitching George H. , Hoff Michael
Published: September 2017

Let $C$ be a Petri general curve of genus $g$ and $E$ a general stable vector bundle of rank $r$ and slope $g-1$ over $C$ with $h^{0}(C,E)=r+1$. For $g\geqslant (2r+2)(2r+1)$, we show how the bundle $E$ can be recovered from the tangent cone to the generalised theta divisor $\unicode[STIX]{x1D6E9}_{E}$ at ${\mathcal{O}}_{C}$. We use this to give a constructive proof and a sharpening of Brivio and Verra’s theorem that the theta map $\mathit{SU}_{C}(r){\dashrightarrow}|r\unicode[STIX]{x1D6E9}|$ is generically injective for large values of $g$.
Detailed Analysis of the Wake Structure of a Straight-Blade H-Darrieus Wind Turbine by Means of Wind Tunnel Experiments and Computational Fluid Dynamics Simulations
Authors: Bianchini Alessandro , Balduzzi Francesco , Ferrara Giovanni , Ferrari Lorenzo , Persico Giacomo , Dossena Vincenzo , Battisti Lorenzo
Published: September 2017

Darrieus vertical axis wind turbines (VAWTs) have been recently identified as the most promising solution for new types of applications, such as small-scale installations in complex terrains or offshore large floating platforms. To improve their efficiencies further and make them competitive with those of conventional horizontal axis wind turbines, a more in depth understanding of the physical phenomena that govern the aerodynamics past a rotating Darrieus turbine is needed. Within this context, computational fluid dynamics (CFD) can play a fundamental role, since it represents the only model able to provide a detailed and comprehensive representation of the flow. Due to the complexity of similar simulations, however, the possibility of having reliable and detailed experimental data to be used as validation test cases is pivotal to tune the numerical tools. In this study, a two-dimensional (2D) unsteady Reynolds-averaged Navier–Stokes (U-RANS) computational model was applied to analyze the wake characteristics on the midplane of a small-size H-shaped Darrieus VAWT. The turbine was tested in a large-scale, open-jet wind tunnel, including both performance and wake measurements. Thanks to the availability of such a unique set of experimental data, systematic comparisons between simulations and experiments were carried out for analyzing the structure of the wake and correlating the main macrostructures of the flow to the local aerodynamic features of the airfoils in cycloidal motion. In general, good agreement on the turbine performance estimation was constantly appreciated.
Blue Refrigeration: Capacitive De-ionization for Brackish Water Treatment
Authors: Hatzell Marta C. , Hatzell Kelsey B.
Published: September 2017

There is a growing interest in minimizing the energy and cost associated with desalination. To do this, various new desalination systems and approaches are being explored. One growing area of interest revolves around electrochemical separations for deionization. Electrochemical separations primarily consist of technologies which either intercalate or electroadorb species of interest from a bulk mixture. This can be conducted through polarizing a battery electrode, or more commonly a capacitive electrode. One example is the technology capacitive deionization (CDI). CDI is being investigated as a means to augment the current state of the art, and as a stand-alone brackish water treatment technology. Despite the potential of this technology, there is still much that is not known regarding the energetics and efficiency of both the desalination and brine formation process. Here, blue refrigeration is a term used to broadly describe desalination cycles and processes. The analogy aims to compare the energetics associated with a desalination cycle to the energetics well studied in thermal refrigeration cycles. This perspective aims to evaluate some of the emerging energetic issues associated with CDI, and to describe how new system architectures may play a role in achieving more ideal energy and desalination performance.
Numerical Model of Liquid Film Formation and Breakup in Last Stage of a Low-Pressure Steam Turbine
Authors: Rossi Pietro , Raheem Asad , Abhari Reza S.
Published: September 2017

Formation of thin liquid films on steam turbine airfoils, particularly in last stages of low-pressure (LP) steam turbines, and their breakup into coarse droplets is of paramount importance to assess erosion of last stage rotor blades given by the impact of those droplets. An approach for this problem is presented in this paper: this includes deposition of liquid water mass and momentum, film mass and momentum conservation, trailing edge breakup and droplets Lagrangian tracking accounting for inertia and drag. The use of thickness-averaged two-dimensional (2D) equations in local body-fitted coordinates, derived from Navier–Stokes equations, makes the approach suitable for arbitrary curved blades and integration with three-dimensional (3D) computational fluid dynamics (CFD) simulations. The model is implemented in the in-house solver MULTI3, which uses Reynolds-averaged Navier–Stokes equations κ – ω model and steam tables for the steam phase and was previously modified to run on multi-GPU architecture. The method is applied to the last stage of a steam turbine in full and part load operating conditions to validate the model by comparison with time-averaged data from experiments conducted in the same conditions. Droplets impact pattern on rotor blades is also predicted and shown.
Imaging the halogen bond in self-assembled halogenbenzenes on silver
Authors: Han Zhumin , Czap Gregory , Chiang Chi-lun , Xu Chen , Wagner Peter J. , Wei Xinyuan , Zhang Yanxing , Wu Ruqian , Ho W.
Published: September 2017

Visualizing halogen bonding

Even though halogen atoms are highly electronegative, a noncovalent bond can form between an electron donor and a halogen atom in a covalent bond. Such interactions are facilitated by the formation of electron-depleted regions in the halogen's covalent bond, a situation least likely for fluorine atoms. Han
et al.
used noncontact scanning tunneling microscopy with submolecular resolution to explore how the size and polarizability of halogens affect complex formation by halogenated benzene molecules adsorbed on a silver surface (see the Perspective by Neaton). With the help of density functional theory, they show how several weak interactions, including van der Waals forces, electrostatic repulsions, and halogen bonds, affect structure.

Science
, this issue p.
206
; see also p.
167
Draft Genome Sequence of Prevotella copri Isolated from the Gut of a Healthy Indian Adult
Authors: Bag Satyabrata , Ghosh Tarini Shankar , Das Bhabatosh
Published: September 2017

Prevotella copri
, a Gram-negative anaerobic rod-shaped bacterium, is frequently associated with the human gastrointestinal tract and influences host physiology, immunity, and metabolic pathways. In the present study, we report the draft genome sequence of
P. copri
isolated from the gut of a healthy Indian adult.
Complete Genome Sequence of a Shiga Toxin-Producing Enterobacter cloacae Clinical Isolate
Authors: Carter Michelle Qiu , Pham Antares , Huynh Steven , He Xiaohua
Published: September 2017

Enterobacter cloacae
strain M12X01451 was isolated from a patient with mild diarrhea. This strain produces a novel subtype of Shiga toxin 1, Stx1e. The Stx1e-converting prophage in strain M12X01451 is stable and can infect other bacteria following induction. Here we report the complete genome sequence and annotation of strain M12X01451.
Draft Genome Sequence of Bacillus thuringiensis subsp.
aizawai
HD133
Authors: Fu Zujiao , Xiao Rong , Luo Rongjun , Hu Zhan , Yang Hua , Guo Zhaohui , Lei Ping , Shan Shiping
Published: September 2017

We report here the 6,512,057-bp draft genome sequence of
Bacillus thuringiensis
subsp.
aizawai
HD133. This strain contains at least 6
cry
genes and 13 candidate biosynthetic gene clusters.
Genome Sequence of Grapevine Virus T, a Novel Foveavirus Infecting Grapevine
Authors: Jo Yeonhwa , Song Myung-Kyu , Choi Hoseong , Park Jae-Seong , Lee Jae-Wung , Lian Sen , Lee Bong Choon , Cho Won Kyong
Published: September 2017

Here, we report the genome sequence of grapevine virus T (GVT), a novel single-stranded RNA virus identified from a transcriptome of grapevine. The genome of GVT is 8,701 nucleotides in length and encodes five open reading frames. GVT is a putative member of the genus
Foveavirus
in the family
Betaflexiviridae
.
Draft Genome Sequence of
Paenibacillus
sp. XY044, a Potential Plant Growth Promoter Isolated from a Tea Plant
Authors: Liu Huihui , Shan Wenna , Zhou Ying , Yu Xiaomin
Published: September 2017

Paenibacillus
sp. XY044 is an endophytic bacterium isolated from the stem of a tea plant (
Camellia sinensis
cv. Maoxie). Here, we present the draft genome sequence of XY044, which includes genes encoding features related to plant growth promotion and biocontrol.
Neonatal resuscitation using a laryngeal mask airway: a randomised trial in Uganda
Authors: Pejovic Nicolas J , Trevisanuto Daniele , Lubulwa Clare , Myrnerts Höök Susanna , Cavallin Francesco , Byamugisha Josaphat , Nankunda Jolly , Tylleskär Thorkild
Published: September 2017

Objective

Mortality rates from birth asphyxia in low-income countries remain high. Face mask ventilation (FMV) performed by midwives is the usual method of resuscitating neonates in such settings but may not always be effective. The i-gel is a cuffless laryngeal mask airway (LMA) that could enhance neonatal resuscitation performance. We aimed to compare LMA and face mask (FM) during neonatal resuscitation in a low-resource setting.

Setting

Mulago National Referral Hospital, Kampala, Uganda.

Design

This prospective randomised clinical trial was conducted at the labour ward operating theatre. After a brief training on LMA and FM use, infants with a birth weight >2000 g and requiring positive pressure ventilation at birth were randomised to resuscitation by LMA or FM. Resuscitations were video recorded.

Main outcome measures

Time to spontaneous breathing.

Results

Forty-nine (24 in the LMA and 25 in the FM arm) out of 50 enrolled patients were analysed. Baseline characteristics were comparable between the two arms. Time to spontaneous breathing was shorter in LMA arm than in FM arm (mean 153 s (SD±59) vs 216 s (SD±92)). All resuscitations were effective in LMA arm, whereas 11 patients receiving FM were converted to LMA because response to FMV was unsatisfactory. There were no adverse effects.

Conclusion

A cuffless LMA was more effective than FM in reducing time to spontaneous breathing. LMA seems to be safe and effective in clinical practice after a short training programme. Its potential benefits on long-term outcomes need to be assessed in a larger trial.

Clinical trial registry

This trial was registered in https://clinicaltrials.gov, with registration number NCT02042118.
[18F]AV-1451 binding in vivo mirrors the expected distribution of TDP-43 pathology in the semantic variant of primary progressive aphasia
Authors: Bevan-Jones W R , Cope Thomas E , Jones P Simon , Passamonti Luca , Hong Young T , Fryer Tim D , Arnold Robert , Allinson Kieren S J , Coles Jonathan P , Aigbirhio Franklin I , Patterson Karalyn , O’Brien John T , Rowe James B
Published: September 2017

Introduction

Semantic dementia, including the semantic variant of primary progressive aphasia (svPPA), is strongly associated with TAR-DNA binding protein 43 (TDP-43) type C pathology. It provides a useful model in which to test the specificity of in vivo binding of the putative tau ligand [18F]AV-1451, which is elevated in frontotemporal lobar degeneration tauopathies.

Methods and results

Seven patients (five with svPPA and two with ‘right’ semantic dementia) and 12 healthy controls underwent positron emission tomography brain imaging with [18F]AV-1451. Two independent preprocessing methods were used. For both methods, all patients had clearly elevated binding potential (BPND(non-displaceable binding potential)) in temporal lobes, lateralising according to their clinical syndrome and evident in raw images. Region of interest analyses confirmed that BPNDwas significantly increased in temporal regions, insula and fusiform gyrus, consistent with those areas known to be most affected in semantic dementia. Hierarchical cluster analysis, based on the distribution of [18F]AV-1451 binding potential, separated semantic dementia from controls with 86% sensitivity and 100% specificity.

Conclusions

[18F]AV-1451 binds in vivo regions that are likely to contain TDP-43 and not significant tau pathology. While this suggests a non-tau target for [18F]AV-1451, the pathological regions in semantic dementia do not normally contain significant levels of recently proposed ‘off target’ binding sites for [18F]AV-1451, such as neuronal monoamine oxidase or neuromelanin. Postmortem and longitudinal data will be useful to assess the utility of [18F]AV-1451 to differentiate and track different types of frontotemporal lobar degeneration.
Using best interests meetings for people in a prolonged disorder of consciousness to improve clinical and ethical management
Authors: Wade Derick T
Published: September 2017

Current management of people with prolonged disorders of consciousness is failing patients, families and society. The causes include a general lack of concern, knowledge and expertise; a legal and professional framework which impedes timely and appropriate decision-making and/or enactment of the decision; and the exclusive focus on the patient, with no legitimate means to consider the broader consequences of healthcare decisions. This article argues that a clinical pathway based on the principles of (a) the English Mental Capacity Act 2005 and (b) using time-limited treatment trials could greatly improve patient management and reduce stress on families. There needs to be early and continuing use of formal best interests meetings, starting between 7 and 21 days after onset of unconsciousness (from any cause, including progressive disorders). The treatment options need to evolve as the clinical state and prognosis becomes more certain. A formal discussion of treatment withdrawal should occur when the upper bound of predicted recovery falls below a level the patient would have considered acceptable, and it should always be discussed when the condition is considered permanent. Any decision to stop treatment should be contingent on a formal second opinion from an independent expert who should review the clinical situation and expected prognosis, but not the best interests decision. The article also asks how, if at all, the adverse effects on the family and the resource implications of long-term care of people left in a prolonged state of unconsciousness should be incorporated in the process.
Invitations received from potential predatory publishers and fraudulent conferences: a 12-month early-career researcher experience
Authors: Mercier Eric , Tardif Pier-Alexandre , Moore Lynne , Le Sage Natalie , Cameron Peter A
Published: September 2017

Purpose of the study

This study aims to describe all unsolicited electronic invitations received from potential predatory publishers or fraudulent conferences over a 12-month period following the first publication as a corresponding author of a junior academician.

Study design

Unsolicited invitations received at an institutional email address and perceived to be sent by predatory publishers or fraudulent conferences were collected.

Results

A total of 502 invitations were included of which 177 (35.3%) had subject matter relevant to the recipient’s research interests and previous work. Two hundred and thirty-seven were invitations to publish a manuscript. Few disclosed the publication fees (32, 13.5%) but they frequently reported accepting all types of manuscripts (167, 70.5%) or emphasised on a deadline to submit (165, 69.6%). Invitations came from 39 publishers (range 1 to 87 invitations per publisher). Two hundred and ten invitations from a potential fraudulent conference were received. These meetings were held in Europe (97, 46.2%), North America (65, 31.0%), Asia (20.4%) or other continents (5, 2.4%) and came from 18 meeting organisation groups (range 1 to 137 invitations per organisation). Becoming an editorial board member (30), the editor-in-chief (1), a guest editor for journal special issue (6) and write a book chapter (11) were some of the roles offered in the other invitations included while no invitation to review a manuscript was received.

Conclusions

Young researchers are commonly exposed to predatory publishers and fraudulent conferences following a single publication as a corresponding author. Academic institutions worldwide need to educate and inform young researchers of this emerging problem.
Thiamin deficiency on fetal brain development with and without prenatal alcohol exposure
Authors: Kloss Olena , Eskin N.A. Michael , Suh Miyoung
Published: September 2017

Adequate thiamin levels are crucial for optimal health through maintenance of homeostasis and viability of metabolic enzymes, which require thiamine as a co-factor. Thiamin deficiency occurs during pregnancy when the dietary intake is inadequate or excessive alcohol is consumed. Thiamin deficiency leads to brain dysfunction because thiamin is involved in the synthesis of myelin and neurotransmitters (e.g., acetylcholine, γ-aminobutyric acid, glutamate), and its deficiency increases oxidative stress by decreasing the production of reducing agents. Thiamin deficiency also leads to neural membrane dysfunction, because thiamin is a structural component of mitochondrial and synaptosomal membranes. Similarly, in-utero exposure to alcohol leads to fetal brain dysfunction, resulting in negative effects such as fetal alcohol spectrum disorder (FASD). Thiamin deficiency and prenatal exposure to alcohol could act synergistically to produce negative effects on fetal development; however, this area of research is currently under-studied. This minireview summarizes the evidence for the potential role of thiamin deficiency in fetal brain development, with or without prenatal exposure to alcohol. Such evidence may influence the development of new nutritional strategies for preventing or mitigating the symptoms of FASD.
Efficacy of hyperthermia in human colon adenocarcinoma cells is improved by auraptene
Authors: Moussavi Mahdi , Haddad Farhang , Matin Maryam M. , Iranshahi Mehrdad , Rassouli Fatemeh B.
Published: September 2017

Colon adenocarcinoma is one of the most common cancers worldwide, and resistance to current therapeutic modalities is a serious drawback in its treatment. Auraptene is a natural coumarin with considerable anticancer effects. The goal of this study was to introduce a novel combinatorial approach for treatment against colon adenocarcinoma cells. To do so, HT29 cells were pretreated with nontoxic auraptene and then hyperthermia was induced. Afterwards, the viability of the cells was assessed, changes induced in the cell cycle were analyzed, and the expression patterns of candidate genes were studied. Results from the MTT assay demonstrated significant (p < 0.01) decreases in cell viability when 20 μg/mL auraptene was used for 72 h, heat shock was induced, and cells were allowed to recover for 24 h. Flow cytometry analysis also indicated considerable changes in the distribution of cells between the sub-G1/G1 and G2/M phases of cell cycle after the combinatorial treatment. Real-time RT–PCR studies revealed significant (p < 0.01) up-regulation of P21 in the cells pretreated with auraptene after heat shock, whereas no significant change was observed in HSP27 expression. Our findings not only indicate, for the first time, that the efficacy of hyperthermia was improved by auraptene pretreatment, but also suggest that this coumarin could be used in the future to achieve more effective therapeutic outcomes.
Eigenvalues of transition weight matrix and eigentime identity of weighted network with two hub nodes
Authors: Zou Jiahui , Dai Meifeng , Wang Xiaoqian , Tang Hualong , He Di , Sun Yu , Su Weiyi
Published: September 2017

The eigenvalues of the normalized Laplacian of a graph provide information on its structural properties and also on some relevant dynamical aspects, in particular those related to weight-dependent walk. In this paper, we first present a study on the transition weight matrix of a weighted network. To get the eigentime identity for weight-dependent walk and weighted counting of spanning trees, we need to obtain all the eigenvalues and their multiplicities of the transition weight matrix. Then we obtain the recursive relationship of its eigenvalues at two successive generations of transition weight matrix. By substituting, we can obtain the relationship of normalized Laplacian matrix’s eigenvalues at two successive generations. Using the relationship and Vietas formulas, we obtain the scalings of the eigentime identity. Afterwards, we classify normalized Laplacian matrix’s eigenvalues and compute the product of all nonzero normalized Laplacian eigenvalues by the product recursive relationship. The product is used to obtain weighted counting of spanning trees. Finally, by weighted counting of spanning trees, we validate the obtained eigenvalues and their multiplicities. The obtained results show that the weight factor has a strong effect on the behavior of weight-dependent walks.
A Computational Algorithm for Equilibrium Asset Pricing Under Heterogeneous Information and Short-Sale Constraints
Authors: Tong Jun , Hu Jian-Qiang , Hu Jiaqiao
Published: September 2017

We propose an efficient algorithm for computing the equilibrium of a capital asset pricing model with heterogeneous investors and short-sale constraints. We show that the equilibrium prices of the risky assets in the model are proportional to the Lagrangian multipliers of an equivalent dual formulation of the problem. Based on this observation, we derive sufficient conditions to guarantee the existence and uniqueness of equilibrium and prove the convergence of the algorithm. Numerical examples are also provided to illustrate the algorithm.
A Mathematical Programming Model with Equilibrium Constraints for Competitive Closed-Loop Supply Chain Network Design
Authors: Yang Yuxiang , Huang Zuqing , Qiang Qiang Patrick , Zhou Gengui
Published: September 2017

A firm sets up his facilities including manufacturing/remanufacturing plants and distribution/collection centers, incorporating an existing closed-loop supply chain (CLSC) network. The entering firm has to compete with the existing firms in the existing network. The entering firm behaves as the leader of a Stackelberg game while the existing firms in the existing network are followers. We assume that the entering firm can anticipate the existing firms’ reaction to his potential location decision before choosing his optimal policy. We use a CLSC network equilibrium model in which the decision makers are faced with multiple objectives to capture the existing firms’ reaction. A mathematical programming model with equilibrium constraints is developed for this competitive CLSC network design problem by taking into account the market competition existing in the decentralized CLSC network. A solution method is developed by integrating Genetic algorithm with an inexact logarithmic-quadratic proximal augmented Lagrangian method. Finally, numerical examples and the related results are studied for illustration purpose.
Dielectric properties of (SWCNTs)x GdBa2CuO7−δ superconductor nanocomposites
Authors: Anas M. , Ebrahim S. , Eldeen I. G. , Awad R. , Abou-Aly A. I.
Published: September 2017

Gd-123 superconducting phase was prepared by solid-state reaction technique. Single-walled carbon nanotubes (SWCNTs) were added in Gd-123 superconducting matrix with different concentrations during the final sintering process to obtain (SWCNTs)[Formula: see text] GdBa2Cu3O[Formula: see text] (x = 0.0–0.1 wt.%) nanoparticles–superconductor composite. The influence of SWCNTs addition on the phase formation, structural, morphological, superconducting and dielectric properties of Gd-123 phase was investigated. It was found that SWCNTs addition enhance the phase formation and does not change the crystal structure of the host Gd-123 superconducting phase. The superconducting properties of Gd-123 samples were improved after the addition of SWCNTs up to x = 0.06 wt.% due to the enhancement in intergrain connectivity by healing up of micro-cracks and reduction of defects, while these properties were retarded with further increase in x. The dielectric response of (SWCNTs)[Formula: see text] Gd-123 superconducting phase with x = 0.0, 0.01, 0.04, 0.05, 0.06 and 0.1 wt.% was measured from 100 KHz to 5 MHz at 77 K. The results reveal that for both real ([Formula: see text]) and imaginary ([Formula: see text]) parts of dielectric constant, the frequency of dispersion increased by increasing SWCNTs amount up to 0.06 wt.%, then this frequency shifted to lower values for x [Formula: see text] 0.06 wt.%. The results were discussed according to the presence and interference of both interfacial and dipolar polarizations.
Sterilization by negative and positive DC plasma with a micro discharge gap at atmospheric pressure
Authors: Li Hua , Jiang Lin-Xiu , Jiang Yong-Rong , Zhu Jian-Min , Chen Zhen-Cheng
Published: September 2017

A new needle-to-droplet electrode structure with a micro discharge gap (2 mm) was designed to achieve direct current (DC) discharge plasma in ambient air with the aim of using the plasma to sterilize liquids. Without using noble gases or an external air flow, we succeeded in generating both a negative and positive DC plasma at atmospheric pressure. The plasma was driven by a 0 to −20,000 V, 100 W DC power supply. A stainless steel needle with a tip diameter of [Formula: see text] and a 200-[Formula: see text] droplet of bacteria-containing liquid served as the electrodes. At atmospheric pressure and room temperature (23[Formula: see text]C), utilizing the negative DC plasma, the discharge time lasted 10 s; the results showed that the higher the discharge voltage, the more efficient the sterilization effect. Conversely, when we applied a voltage of −5.5 kV, we found that the sterilization effect was more efficient for longer discharge times. Our findings demonstrate that Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) can be killed in about 30 s. Our experiments show that our sterilization method required less time and was more efficient for positive than for negative DC plasma under the same conditions.
Carter constant and angular momentum
Authors: Mukherjee Sajal , Nayak K. Rajesh
Published: September 2017

We investigate the Carter-like constant in the case of a particle moving in a nonrelativistic dipolar potential. This special case is a missing link between the Carter constant in stationary and axially symmetric spacetimes (SASS) such as Kerr solution and its possible Newtonian counterpart. We use this system to carry over the definition of angular momentum from the Newtonian mechanics to the relativistic SASS.
Cohen-Macaulay Lexsegment Complexes in Arbitrary Codimension
Authors: Haghighi Hassan , Yassemi Siamak , Zaare-Nahandi Rahim
Published: September 2017

We characterize pure lexsegment complexes which are Cohen-Macaulay in arbitrary codimension. More precisely, we prove that any lexsegment complex is Cohen-Macaulay if and only if it is pure and its 1-dimensional links are connected, and that a lexsegment flag complex is Cohen-Macaulay if and only if it is pure and connected. We show that any non-Cohen-Macaulay lexsegment complex is a Buchsbaum complex if and only if it is a pure disconnected flag complex. For [Formula: see text], a lexsegment complex is strictly Cohen-Macaulay in codimension t if and only if it is the join of a lexsegment pure disconnected flag complex with a [Formula: see text]-dimensional simplex. When the Stanley-Reisner ideal of a pure lexsegment complex is not quadratic, the complex is Cohen-Macaulay if and only if it is Cohen-Macaulay in some codimension. Our results are based on a characterization of Cohen-Macaulay and Buchsbaum lexsegment complexes by Bonanzinga, Sorrenti and Terai.
On Connected Tetravalent Cayley Graphs of a Non-abelian Group of Order 3p2
Authors: Darafsheh M.R. , Abdollahi M.
Published: September 2017

In this paper we determine all tetravalent Cayley graphs of a non-abelian group of order 3p2, where p is a prime number greater than 3, and with a cyclic Sylow p-subgroup. We show that all of these tetravalent Cayley graphs are normal. The full automorphism group of these Cayley graphs is given and the half-transitivity and the arc-transitivity of these graphs are investigated. We show that this group is a 5-CI-group.
Embedding Countably Generated Algebras into Simple 2-Generated Algebras
Authors: Mo Qiuhui , Zhao Xiangui , Pan Qingnian
Published: September 2017

In this paper, by using Gröbner-Shirshov bases theories, we prove that each countably generated associative differential algebra (resp., associative Ω-algebra, associative λ-differential algebra) can be embedded into a simple 2-generated associative differential algebra (resp., associative Ω-algebra, associative λ-differential algebra).
Existence results for diffusion–convection equations of nonlinear unilateral problems defined in Orlicz–Sobolev spaces
Authors: Moussa H. , Rhoudaf M. , Sabiki H.
Published: September 2017

We prove the existence result of unilateral problems associated to strongly nonlinear elliptic equations whose model, including the diffusion–convection equation, is [Formula: see text]. We study exactly the following general case [Formula: see text] where [Formula: see text] is a Leray–Lions operator having a growth not necessarily of polynomial type, the lower order term [Formula: see text] : [Formula: see text] is a Carathéodory function, for a.e. [Formula: see text] and for all [Formula: see text] satisfying only a growth condition and the right-hand side [Formula: see text] belongs to [Formula: see text].
Positivity and recursion formula of the linearization coefficients of Bessel polynomials
Authors: Benabdallah M. , Atia M. J.
Published: September 2017

Positivity of the linearization coefficients for Bessel polynomials is proved in a more general case. The proof is based not only on a recursion formula (a formula similar to one given by Berg and Vignat) but also on giving an explicit triple sum formula. Moreover, this triple sum is simplified and a double sum formula for these linearization coefficients is given. In two general cases, this formula reduces indeed to either Atia and Zeng’s formula (M. J. Atia and J. Zeng, An explicit formula for the linearization coefficients of Bessel polynomials, Ramanujan J. 28(2) (2012) 211–221, doi: 10.1007/s11139-011-9348-4) or Berg and Vignat’s formulas in their proof of the positivity results about these coefficients (C. Berg and C. Vignat, Linearization coefficients of Bessel polynomials and properties of student [Formula: see text]-distributions, Constr. Approx. 27 (2008) 15–32).
Ideals of core regular double Stone algebra
Authors: Srikanth A. R. J. , Ravi Kumar R. V. G.
Published: September 2017

A regular double Stone algebra with nonvoid core is called core regular double Stone algebra (CRDSA) [6] and this particular core element affects the behavior of the algebra in certain aspects especially in characterization of maximal and prime ideals. In this paper, an elegant characterization for maximal and prime ideals of a CRDSA is established.
Bifrost: A Python/C++ Framework for High-Throughput Stream Processing in Astronomy
Authors: Cranmer Miles D. , Barsdell Benjamin R. , Price Danny C. , Dowell Jayce , Garsden Hugh , Dike Veronica , Eftekhari Tarraneh , Hegedus Alexander M. , Malins Joseph , Obenberger Kenneth S. , Schinzel Frank , Stovall Kevin , Taylor Gregory B. , Greenhill Lincoln J.
Published: September 2017

Radio astronomy observatories with high throughput back end instruments require real-time data processing. While computing hardware continues to advance rapidly, development of real-time processing pipelines remains difficult and time-consuming, which can limit scientific productivity. Motivated by this, we have developed Bifrost: an open-source software framework for rapid pipeline development. (a) Bifrost combines a high-level Python interface with highly efficient reconfigurable data transport and a library of computing blocks for CPU and GPU processing. The framework is generalizable, but initially it emphasizes the needs of high-throughput radio astronomy pipelines, such as the ability to process data buffers as if they were continuous streams, the capacity to partition processing into distinct data sequences (e.g. separate observations), and the ability to extract specific intervals from buffered data. Computing blocks in the library are designed for applications such as interferometry, pulsar dedispersion and timing, and transient search pipelines. We describe the design and implementation of the Bifrost framework and demonstrate its use as the backbone in the correlation and beamforming back end of the Long Wavelength Array (LWA) station in the Sevilleta National Wildlife Refuge, NM.
Algorithms versus mechanisms
Authors: Niazadeh Rad
Published: September 2017

Online markets and platforms rely on human user decisions as inputs. This generates the challenge of managing user incentives and misbehaviors as strategic entities. Surprisingly, one can show that designers do not require much additional computational power to overcome this challenge.
Incentives and the crowd
Authors: Vaughan Jennifer Wortman
Published: September 2017

Crowdsourcing gives us a way to leverage the complementary strengths of humans and machines. But how do we solve the problem of low-quality crowdwork?
Games user research and gamification in human-computer interaction
Authors: Nacke Lennart E.
Published: September 2017

Video games inspire new tools for creating engaging user experiences.
Role of Morphology Injection in SMT
Authors: S Sreelekha , Bhattacharyya Pushpak
Published: September 2017

Phrase-based Statistical Machine Translation (PBSMT) is commonly used for automatic translation. However, PBSMT runs into difficulty when either or both of the source and target languages are morphologically rich. Factored models are found to be useful for such cases, as they consider word as a vector of factors. These factors can contain any information about the surface word and use it while translating. The objective of the current work is to handle morphological inflections in Hindi, Marathi, and Malayalam using Factored translation models when translating from English. Statistical MT approaches face the problem of data sparsity when translating to a morphologically rich language. It is very unlikely for a parallel corpus to contain all morphological forms of words. We propose a solution to generate these unseen morphological forms and inject them into the original training corpus. We propose a simple and effective solution based on enriching the input with various morphological forms of words. We observe that morphology injection improves the quality of translation in terms of both adequacy and fluency. We verify this with experiments on three morphologically rich languages when translating from English. From the detailed evaluations, we observed an order of magnitude improvement in translation quality.
Automatic program inversion using symbolic transducers
Authors: Hu Qinheping , D'Antoni Loris
Published: September 2017

We propose a fully-automated technique for inverting functional programs that operate over lists such as string encoders and decoders. We consider programs that can be modeled using symbolic extended finite transducers (), an expressive model that can describe complex list-manipulating programs while retaining several decidable properties. Concretely, given a program
P
expressed as an , we propose techniques for: (1) checking whether
P
is injective and, if that is the case, (2) building an
P
-1
describing its inverse. We first show that it is undecidable to check whether an is injective and propose an algorithm for checking injectivity for a restricted, but a practical class of . We then propose an algorithm for inverting based on the following idea: if an is injective, inverting it amounts to inverting all its individual transitions. We leverage recent advances program synthesis and show that the transition inversion problem can be expressed as an instance of the syntax-guided synthesis framework. Finally, we implement the proposed techniques in a tool called and show that can invert 13 out 14 real complex string encoders and decoders, producing inverse programs that are substantially identical to manually written ones.
Accelerating GPU Hardware Transactional Memory with Snapshot Isolation
Authors: Chen Sui , Peng Lu , Irving Samuel
Published: September 2017

Snapshot Isolation (SI) is an established model in the database community, which permits write-read conflicts to pass and aborts transactions only on write-write conflicts. With the Write Skew anomaly correctly eliminated, SI can reduce the occurrence of aborts, save the work done by transactions, and greatly benefit long transactions involving complex data structures.

GPUs are evolving towards a general-purpose computing device with growing support for irregular workloads, including transactional memory. The usage of snapshot isolation on transactional memory has proven to be greatly beneficial for performance. In this paper, we propose a multi-versioned memory subsystem for hardware-based transactional memory on the GPU, with a method for eliminating the Write Skew anomaly on the fly, and finally incorporate Snapshot Isolation with this system.

The results show that snapshot isolation can effectively boost the performance of dynamically sized data structures such as linked lists, binary trees and red-black trees, sometimes by as much as 4.5x, which results in improved overall performance of benchmarks utilizing these data structures.
Hardware Translation Coherence for Virtualized Systems
Authors: Yan Zi , Veselý Ján , Cox Guilherme , Bhattacharjee Abhishek
Published: September 2017

To improve system performance, operating systems (OSes) often undertake activities that require modification of virtual-to-physical address translations. For example, the OS may migrate data between physical pages to manage heterogeneous memory devices. We refer to such activities as page remappings. Unfortunately, page remappings are expensive. We show that a big part of this cost arises from address translation coherence, particularly on systems employing virtualization. In response, we propose hardware translation invalidation and coherence or HATRIC, a readily implementable hardware mechanism to piggyback translation coherence atop existing cache coherence protocols. We perform detailed studies using KVM-based virtualization, showing that HATRIC achieves up to 30% performance and 10% energy benefits, for per-CPU area overheads of 0.2%. We also quantify HATRIC's benefits on systems running Xen and find up to 33% performance improvements.
MCM-GPU
Authors: Arunkumar Akhil , Bolotin Evgeny , Cho Benjamin , Milic Ugljesa , Ebrahimi Eiman , Villa Oreste , Jaleel Aamer , Wu Carole-Jean , Nellans David
Published: September 2017

Historically, improvements in GPU-based high performance computing have been tightly coupled to transistor scaling. As Moore's law slows down, and the number of transistors per die no longer grows at historical rates, the performance curve of single monolithic GPUs will ultimately plateau. However, the need for higher performing GPUs continues to exist in many domains. To address this need, in this paper we demonstrate that package-level integration of multiple GPU modules to build larger logical GPUs can enable continuous performance scaling beyond Moore's law. Specifically, we propose partitioning GPUs into easily manufacturable basic GPU Modules (GPMs), and integrating them on package using high bandwidth and power efficient signaling technologies. We lay out the details and evaluate the feasibility of a basic Multi-Chip-Module GPU (MCM-GPU) design. We then propose three architectural optimizations that significantly improve GPM data locality and minimize the sensitivity on inter-GPM bandwidth. Our evaluation shows that the optimized MCM-GPU achieves 22.8% speedup and 5x inter-GPM bandwidth reduction when compared to the basic MCM-GPU architecture. Most importantly, the optimized MCM-GPU design is 45.5% faster than the largest implementable monolithic GPU, and performs within 10% of a hypothetical (and unbuildable) monolithic GPU. Lastly we show that our optimized MCM-GPU is 26.8% faster than an equally equipped Multi-GPU system with the same total number of SMs and DRAM bandwidth.
Viyojit
Authors: Kateja Rajat , Badam Anirudh , Govindan Sriram , Sharma Bikash , Ganger Greg
Published: September 2017

Non-Volatile Memories (NVMs) can significantly improve the performance of data-intensive applications. A popular form of NVM is Battery-backed DRAM, which is available and in use today with DRAMs latency and without the endurance problems of emerging NVM technologies. Modern servers can be provisioned with up-to 4 TB of DRAM, and provisioning battery backup to write out such large memories is hard because of the large battery sizes and the added hardware and cooling costs. We present Viyojit, a system that exploits the skew in write working sets of applications to provision substantially smaller batteries while still ensuring durability for the entire DRAM capacity. Viyojit achieves this by bounding the number of dirty pages in DRAM based on the provisioned battery capacity and proactively writing out infrequently written pages to an SSD. Even for write-heavy workloads with less skew than we observe in analysis of real data center traces, Viyojit reduces the required battery capacity to 11% of the original size, with a performance overhead of 7-25%. Thus, Viyojit frees battery-backed DRAM from stunted growth of battery capacities and enables servers with terabytes of battery-backed DRAM.
In-Datacenter Performance Analysis of a Tensor Processing Unit
Authors: Jouppi Norman P. , Young Cliff , Patil Nishant , Patterson David , Agrawal Gaurav , Bajwa Raminder , Bates Sarah , Bhatia Suresh , Boden Nan , Borchers Al , Boyle Rick , Cantin Pierre-luc , Chao Clifford , Clark Chris , Coriell Jeremy , Daley Mike , Dau Matt , Dean Jeffrey , Gelb Ben , Ghaemmaghami Tara Vazir , Gottipati Rajendra , Gulland William , Hagmann Robert , Ho C. Richard , Hogberg Doug , Hu John , Hundt Robert , Hurt Dan , Ibarz Julian , Jaffey Aaron , Jaworski Alek , Kaplan Alexander , Khaitan Harshit , Killebrew Daniel , Koch Andy , Kumar Naveen , Lacy Steve , Laudon James , Law James , Le Diemthu , Leary Chris , Liu Zhuyuan , Lucke Kyle , Lundin Alan , MacKean Gordon , Maggiore Adriana , Mahony Maire , Miller Kieran , Nagarajan Rahul , Narayanaswami Ravi , Ni Ray , Nix Kathy , Norrie Thomas , Omernick Mark , Penukonda Narayana , Phelps Andy , Ross Jonathan , Ross Matt , Salek Amir , Samadiani Emad , Severn Chris , Sizikov Gregory , Snelham Matthew , Souter Jed , Steinberg Dan , Swing Andy , Tan Mercedes , Thorson Gregory , Tian Bo , Toma Horia , Tuttle Erick , Vasudevan Vijay , Walter Richard , Wang Walter , Wilcox Eric , Yoon Doe Hyun
Published: September 2017

Many architects believe that major improvements in cost-energy-performance must now come from domain-specific hardware. This paper evaluates a custom ASIC---called a Tensor Processing Unit (TPU) --- deployed in datacenters since 2015 that accelerates the inference phase of neural networks (NN). The heart of the TPU is a 65,536 8-bit MAC matrix multiply unit that offers a peak throughput of 92 TeraOps/second (TOPS) and a large (28 MiB) software-managed on-chip memory. The TPU's deterministic execution model is a better match to the 99th-percentile response-time requirement of our NN applications than are the time-varying optimizations of CPUs and GPUs that help average throughput more than guaranteed latency. The lack of such features helps explain why, despite having myriad MACs and a big memory, the TPU is relatively small and low power. We compare the TPU to a server-class Intel Haswell CPU and an Nvidia K80 GPU, which are contemporaries deployed in the same datacenters. Our workload, written in the high-level TensorFlow framework, uses production NN applications (MLPs, CNNs, and LSTMs) that represent 95% of our datacenters' NN inference demand. Despite low utilization for some applications, the TPU is on average about 15X -- 30X faster than its contemporary GPU or CPU, with TOPS/Watt about 30X -- 80X higher. Moreover, using the CPU's GDDR5 memory in the TPU would triple achieved TOPS and raise TOPS/Watt to nearly 70X the GPU and 200X the CPU.
Left ventricular strain rate is reduced during voluntary apnea in healthy humans
Authors: Smith Joshua R. , Sutterfield Shelbi L. , Baumfalk Dryden R. , Didier Kaylin D. , Hammer Shane M. , Caldwell Jacob T. , Ade Carl J.
Published: September 2017

During an apneic event, sympathetic nerve activity increases resulting in subsequent increases in left ventricular (LV) afterload and myocardial work. It is unknown how cardiac mechanics are acutely impacted by the increased myocardial work during an apneic event. Ten healthy individuals (23 ± 3 yr) performed multiple voluntary end-expiratory apnea (VEEA) maneuvers exposed to room air, while a subset ( n = 7) completed multiple VEEA exposed to hyperoxic air (100% [Formula: see text]). Beat-by-beat blood pressure, heart rate, and stroke volume were measured continuously. Effective arterial elastance (EA) was calculated as an index of cardiac afterload, and myocardial work was calculated as the rate pressure product (RPP). Tissue Doppler echocardiography was used to measure LV tissue velocities, deformation via strain, and strain rate (SR). Systolic blood pressure (Δ18 ± 13 mmHg, P < 0.01), EA (Δ0.13 ± 0.10 mmHg/ml, P < 0.01), and RPP (Δ9 ± 10 beats/min × mmHg 10−2, P < 0.01) significantly increased with room air VEEA. This occurred in parallel with decreases in peak longitudinal systolic (Δ−0.62 ± 0.41 cm/s, P < 0.01) and early LV filling (Δ−2.81 ± 1.99 cm/s, P < 0.01) myocardial velocities. Longitudinal SR (Δ−0.30 ± 0.32 1/s, P = 0.01) was significantly decreased during room air VEEA. VEEA with hyperoxia did not alter ( P > 0.18) EA or RPP and attenuated the systolic blood pressure response compared with room air. Myocardial velocities and LV strain rate response to VEEA were unchanged ( P = 0.30) with hyperoxia. Consistent with our hypotheses, VEEA-induced increases in EA and myocardial work impact LV mechanics, which may depend, in part, on stimulation of peripheral chemoreceptors.

NEW & NOTEWORTHY Transient increases in arterial blood pressure and systemic vascular resistance occur during sleep apnea events and may contribute to the associated daytime hypertension and risk of overt cardiovascular disease. To date, the link between this apnea pressor response and acute changes in left ventricular function remains poorly understood. We demonstrate that in parallel to increases in cardiac afterload a depressed left ventricular systolic function occurs at end apnea.