bluuebunny/crossref_metadata_2025 huggingface dataset:
Left Ventricular Three‐Dimensional Quadripolar Lead Acute Clinical Study: The LILAC Study
Authors: PHILIPPON FRANÇOIS , LIU LILI , FUNG JEFFREY WING‐HONG , DEHARO JEAN‐CLAUDE , ANSELME FREDERIC , DELNOY PETER PAUL , CRIJNS HARRY , MORILLO CARLOS A. , KRAHN ANDREW D. , GUTLEBEN KLAUS , DELUMEAU JULIEN , MOLIN FRANCK
Published: January 2015

Aims

This multicenter acute clinical study was designed to verify novel three‐dimensional (3D) quadripolar lead designs that can achieve ≤2.5 V average pacing capture threshold (PCT) not only at the apex, but also at the base of the left ventricle with phrenic nerve stimulation (PNS) avoidance for cardiac resynchronization.

Methods

During the implant procedure, up to two different left ventricular investigational leads were introduced and tested in the same target coronary vein based on the coronary sinus venogram in a wedged and unwedged position. Adverse events were collected in 30 days following the procedure.

Results

Eighty‐seven leads were tested in 50 patients. When the best performing spiral electrode was chosen from each lead testing, the average of the best PCT on spiral in a wedged position was similar to the unwedged position (1.7 ± 1.5 V vs 1.9 ± 1.5 V, P = ns) and was similar to the wedged tip electrode average PCT (1.7 ± 1.5 V vs 1.6 ± 1.6 V, P = ns). In the majority of patients (89–96%), pacing was achievable in a mid‐basal ventricular location without PNS.

Conclusions

This acute study demonstrated that a 3D quadripolar spiral lead design can achieve acceptable PCTs and avoid PNS without repositioning the lead at implant in the vast majority of patients. It also demonstrated that this lead design can achieve mid‐basal ventricular stimulation with low PCT and good acute stability.
Cardiac Resynchronization Therapy Acutely Improves Ventricular‐Arterial Coupling by Reducing the Arterial Load: Assessment by Pressure–Volume Loops
Authors: PIERAGNOLI PAOLO , PEREGO GIOVANNI BATTISTA , RICCIARDI GIUSEPPE , SACCHI STEFANIA , PADELETTI MARGHERITA , MICHELUCCI ANTONIO , VALSECCHI SERGIO , PADELETTI LUIGI
Published: January 2015

Background

Cardiac resynchronization therapy (CRT) has been demonstrated to improve ventricular‐arterial coupling by reducing effective arterial elastance (Ea) on long‐term follow‐up. Detailed invasive studies showing possible acute peripheral effects of CRT are not available. We evaluated the hemodynamic effects of CRT in patients with systolic dysfunction, in order to investigate the impact on ventricular‐arterial coupling and, in particular, on Ea immediately after the initiation of pacing.

Methods

We studied 37 heart failure patients undergoing CRT implantation based on conventional criteria. On implantation, left ventricular (LV) pressure and volume data were determined via a conductance catheter. Twelve patients with a standard indication for electrophysiologic study and preserved LV function served as a control group.

Results

In comparison with the control group, heart failure patients showed reduced systolic and diastolic function. LV end‐systolic elastance (Ees: end‐systolic pressure/volume) was impaired (0.79 ± 0.33 mm Hg/mL vs 1.84 ± 0.89 mm Hg/mL, P = 0.012) and Ees/Ea reduced (0.36 ± 0.17 vs 1.19 ± 1.81, P = 0.022). In heart failure patients, CRT immediately improved systolic function, increasing stroke work from 3.9 ± 1.8 L*mm Hg to 6.9 ± 3.3 L*mm Hg (P < 0.001) and Ees to 1.02 ± 0.62 mm Hg/mL (P = 0.001). Ea decreased from 2.59 ± 1.35 mm Hg/mL to 1.68 ± 0.91 mm Hg/mL (P < 0.001), leading to an increase in Ees/Ea to 0.70 ± 0.38 (P < 0.001).

Conclusion

Our data indicate that switching CRT on induces an immediate reduction in arterial load, conceivably as a consequence of restored autonomic balance.
Risk Prediction for Adverse Events during Initiation of Sotalol and Dofetilide for the Treatment of Atrial Fibrillation
Authors: AGUSALA KARTIK , OESTERLE ADAM , KULKARNI CHIRAAG , CAPRIO TIMOTHY , SUBACIUS HARIS , PASSMAN ROD
Published: January 2015

Background

Inpatient antiarrhythmic drug initiation for atrial fibrillation is mandated for dofetilide (DF) and is often performed for sotalol (SL), particularly if proarrhythmia risk factors are present. Whether low‐risk patients can be identified to safely allow outpatient initiation is unknown.

Methods

A single‐center retrospective cohort study was performed on patients initiated with DF or SL. Risk factors for adverse events (AEs), defined as any arrhythmia or electrocardiogram change requiring dose reduction or cessation, were identified.

Results

Of 329 patients, 227 (69%) received SL and 102 (31%) DF. The cohort had a mean age of 63 ± 13 years; 70% of patients were male and had a baseline QTc of 440 ± 37 ms. A total of 105 AEs occurred in 92 patients: QTc prolongation or ventricular tachyarrhythmia in 70 patients (67% of AEs), bradyarrhythmias in 35 patients (33% of AEs), with some experiencing both AE types. Ventricular arrhythmias were seen in 23 patients (7%) and torsades de pointes in one (0.3%). Total AE rates were similar between drugs (P = 0.09); however, DF patients had more QTc prolongation or ventricular arrhythmias (P = 0.001). In SL patients, there were no predictors for QTc prolongation or ventricular proarrhythmia. In DF patients, higher baseline QTc interval (odds ratio = 1.64/25 ms, P = 0.01) was an independent predictor of QTc prolongation or ventricular proarrhythmias. For patients without proarrhythmia risk factors, overall AE rate was 26%.

Conclusions

In conclusion, AEs are common during DF and SL initiation but rarely severe in hospitalized inpatients. Baseline QTc predicts AEs for DF patients only and AE are common even in “low‐risk” patients. These results support in‐hospital drug initiation for all DF and SL patients.
Thromboembolic Events 7–11 Years after Catheter Ablation of Atrial Fibrillation
Authors: TRAN VAN NAM , TESSITORE ELENA , GENTIL‐BARON PASCALE , JANNOT ANNE‐SOPHIE , SUNTHORN HENRI , BURRI HARAN , MACH FRANÇOIS , SHAH DIPEN
Published: January 2015

Background

The results of catheter ablation of atrial fibrillation (AF) beyond 6 years remain unknown. The goal of this study is to assess the risk of thromboembolic events (TEs) and outcomes of AF ablation at long‐term follow‐up (FU).

Methods

All patients who had AF ablation from 2002 until 2005 in our center were contacted for a FU including a questionnaire, cardiac rhythm monitoring, and transthoracic echocardiography.

Results

Among the 264 eligible patients, 164 (62%) completed the study. The mean FU was 9.1 years (7.7–10.5). Seven patients had a TE during FU (event ratio 0.41 per 100 patient years [PY]) and their mean CHA2DS2‐VASc score was 3.1 ± 1.3. Two patients died from stroke (0.14 per 100 PY) and five of the seven were considered in sinus rhythm (SR) and were off anticoagulation at the time of event. Prior to ablation, 13 patients had history of TE, and only one had a TE during FU. Overall, 14 deaths were documented (0.58 per 100 PY). Stable SR was present in 111 patients (68% of 164 patients) after 1.5 ± 0.6 procedures/patient. Univariate analysis showed that dyslipidemia (odds ratio [OR] = 2.95, P = 0.003), CHA2DS2‐VASc ≥2 (OR = 3.22, P = 0.001), and amiodarone (OR = 5.64, P < 0.001) were predictors of long‐term recurrence. Multivariate analysis showed that only CHA2DS2‐VASc ≥2 (OR = 2.67, P = 0.023) and amiodarone (OR = 4.62, P = 0.001) were predictors.

Conclusions

Our study shows low TE rates 9 years after ablation of AF that are lower than published data for AF patients with anticoagulation only. AF patients with a CHA2DS2‐VASc ≥2 should, however, be maintained on anticoagulation.
Decontamination Efficiency of a DBD Lamp Containing an UV–C Emitting Phosphor
Authors: Caillier Bruno , Caiut José Maurício Almeida , Muja Cristina , Demoucron Julien , Mauricot Robert , Dexpert‐Ghys Jeanette , Guillot Philippe
Published: January 2015

Among different physical and chemical agents, the UV radiation appears to be an important route for inactivation of resistant microorganisms. The present study introduces a new mercury‐free Dielectric Barrier Discharge (DBD) flat lamp, where the biocide action comes from the UV emission produced by rare‐earth phosphor obtained by spray pyrolysis, following plasma excitation. In this study, the emission intensity of the prototype lamp is tuned by controlling gas pressure and electrical power, 500 mbar and 15 W, corresponding to optimal conditions. In order to characterize the prototype lamp, the energetic output, temperature increase following lamp ignition and ozone production of the source were measured. The bactericidal experiments carried out showed excellent results for several gram‐positive and gram‐negative bacterial strains, thus demonstrating the high decontamination efficiency of the DBD flat lamp. Finally, the study of the external morphology of the microorganisms after the exposure to the UV emission suggested that other mechanisms than the bacterial DNA damage could be involved in the inactivation process.
Gender and Risk Taking: Evidence From Jumping Competitions
Authors: Böheim René , Lackner Mario
Published: January 2015

We analyse whether female athletes differ from male athletes in their risk-taking behaviour in a competitive setting. Data from high jump and pole vault competitions allow us to identify risky strategies. We estimate whether female athletes use risky strategies as often as male athletes and whether or not their returns to risky strategies differ. Returns to risky strategies are identified via an instrumental variable approach where we use competitive pressure to instrument individual risk taking. Female athletes take fewer risky decisions than men and could improve their outcomes by incurring more risk. We show that competitive pressure results in more risky decisions by both men and women; however, men react stronger to competitive pressure.
Phosphorus control as an effective strategy to adapt soybean to drought at the reproductive stage: evidence from field experiments across northeast China
Authors: Zheng H.F. , Chen L.D. , Yu X.Y. , Zhao X.F. , Ma Y. , Ren Z.B.
Published: January 2015

Drought stress during the reproductive stage is one of the most important constraints on growth and productivity of soybean. There is compelling evidence that physiological and molecular approaches can effectively improve drought resistance in soybean, but strategies derived from soil management are poorly documented, especially under field conditions. In this study, we combined data from field experiments and used multivariate regression analyses to investigate factors determining soybean yield variability over two growing seasons with drought stress during the reproductive stage. Phosphorus application and soil available phosphorus explained a significant proportion of the variation in soybean yield under drought stress. As a whole, soybean fields that received adequate P supply had greater yields than those that did not. However, excessive P application significantly decreased soybean yield. These results suggest that P control is critical to mitigate soybean yield losses resulting from drought at the reproductive stage.
A novel KIR2DL3 variant allele, KIR2DL3*032, which has arisen by a missense mutation in codon 231
Authors: He L. , Zhen J. , Deng Z.
Published: January 2015

The novel 2DL3*032 allele differs from the closest allele KIR2DL3*0010101 by a non‐synonymous mutation in exon 7.
Identification of a novel three‐domain KIR allele: KIR3DL1*087 using high‐resolution molecular techniques
Authors: Yindom L.‐M. , de Silva T. I , Rowland‐Jones S. L.
Published: January 2015

KIR3DL1*087 is significantly different from KIR3DL1*0010101 with multiple non‐synonymous changes and insertion/deletion sites.
Identification of a novel HLA‐A*33 allele, HLA‐*33:03:13, in a Chinese family
Authors: Zou H.‐Y. , Jin S.‐Z. , Li Z.
Published: January 2015

A*33:03:13 differs from A*33:03:01 by one nucleotide change at nucleotide 714 in exon 4 from A to G.
Robust biological nitrogen fixation in a model grass–bacterial association
Authors: Pankievicz Vânia C. S. , do Amaral Fernanda P. , Santos Karina F. D. N. , Agtuca Beverly , Xu Youwen , Schueller Michael J. , Arisi Ana Carolina M. , Steffens Maria. B.R. , de Souza Emanuel M. , Pedrosa Fábio O. , Stacey Gary , Ferrieri Richard A.
Published: January 2015

Nitrogen‐fixing rhizobacteria can promote plant growth; however, it is controversial whether biological nitrogen fixation (BNF) from associative interaction contributes to growth promotion. The roots of Setaria viridis, a model C4 grass, were effectively colonized by bacterial inoculants resulting in a significant enhancement of growth. Nitrogen‐13 tracer studies provided direct evidence for tracer uptake by the host plant and incorporation into protein. Indeed, plants showed robust growth under nitrogen‐limiting conditions when inoculated with an ammonium‐excreting strain of Azospirillum brasilense. 11C‐labeling experiments showed that patterns in central carbon metabolism and resource allocation exhibited by nitrogen‐starved plants were largely reversed by bacterial inoculation, such that they resembled plants grown under nitrogen‐sufficient conditions. Adoption of S. viridis as a model should promote research into the mechanisms of associative nitrogen fixation with the ultimate goal of greater adoption of BNF for sustainable crop production.
Globalisation and Obesity
Authors: Miljkovic Dragan , Shaik Saleem , Miranda Silvia , Barabanov Nikita , Liogier Anais
Published: January 2015

The WHO has recently announced the global obesity epidemic. An economic model is developed in which globalisation factors generate health externalities and contribute to global obesity growth. The unbalanced panel data set contains the information for 79 countries over the period 1986–2008. Fixed‐effects panel data estimation and quantile regression analysis were used to analyse the data. The fixed‐effects panel model results indicate that the impact of trade openness and the globalisation social index (GSI) on global obesity rates is positive and significant, which is consistent with prior expectations, while surprisingly the foreign direct investments (FDI) has no impact on global obesity. While these results are interesting, they are hiding the effect of globalisation processes across the conditional distribution of the obesity variable. The use of quantile regression uncovered that the impact of the FDI and the GSI on low and average quantiles (low and average obesity rates in our sample) is positive and significant, while high quantiles are not affected. Since low and average quantiles (low and average obesity rates) are representative of the less‐ and medium‐developed countries, this result implies that social globalisation and FDI adversely impact obesity in less‐to‐medium developed countries. Trade openness generally has no impact on changes in obesity rates across quantiles.
Theoretical and Experimental Investigations of Solar-Thermoelectric Air-Conditioning System for Remote Applications
Authors: Alomair Muath , Alomair Yazeed , Mahmud Shohel , Abdullah Hussein A.
Published: January 2015

In this paper, we have designed and constructed a low cost solar-thermoelectric (TE) air-conditioning system for people in remote areas where electricity is still in short supply. Such system can be potentially used to condition tents and living areas. The proposed solar-powered TE air-conditioning system is based on the principles of Peltier effect to create a finite temperature difference across the condenser and the evaporator of the TE air-conditioning system. The cold side (or the evaporator) of the TE module is used for air-conditioning application; provides cooling to the living space. The thermal energy from the hot side of the module is dumped to the surrounding environment. Using the existing heat transfer and thermodynamics knowledge, an analytical model is developed to predict the performance of the solar-TE air-conditioning system in terms of the hot and cold reservoir temperatures, heat removal rates from the conditioned space, power input, and coefficient of performance (COP). A second analytical model is proposed to predict the cooling down period of the conditioned space as a function of heat removed by air-conditioning system, heat gained through the wall of the conditioned space, and heat generated inside the conditioned space. A detailed system is constructed to predict the performance of solar-TE air-conditioning system experimentally. A conditioned space was constructed to carry out the experimental work. Multiple air-conditioning systems were installed in the conditioned space. The cooling performance of the designed solar-TE air-conditioning system was experimentally tested and verified with the analytical calculation.
Regulation of dendrimer/dextran material performance by altered tissue microenvironment in inflammation and neoplasia
Authors: Oliva Nuria , Carcole Maria , Beckerman Margarita , Seliktar Sivan , Hayward Alison , Stanley James , Parry Nicola Maria Anne , Edelman Elazer R. , Artzi Natalie
Published: January 2015

Disease type and severity spur specific tissue alterations that can guide formulation of an optimal material for a selected clinical condition.
Inflammasome Activation Contributes to Interleukin-23 Production in Response to Clostridium difficile
Authors: Cowardin Carrie A. , Kuehne Sarah A. , Buonomo Erica L. , Marie Chelsea S. , Minton Nigel P. , Petri William A.
Published: January 2015

Clostridium difficileis the most common hospital-acquired pathogen, causing antibiotic-associated diarrhea in over 250,000 patients annually in the United States. Disease is primarily mediated by toxins A and B, which induce potent proinflammatory signaling in host cells and can activate an ASC-containing inflammasome. Recent findings suggest that the intensity of the host response to infection correlates with disease severity. Our lab has identified the proinflammatory cytokine interleukin-23 (IL-23) as a pathogenic mediator during C. difficile infection (CDI). The mechanisms by which C. difficile induces IL-23, however, are not well understood, and the role of toxins A and B in this process is unclear. Here, we show that toxins A and B alone are not sufficient for IL-23 production but synergistically increase the amount of IL-23 produced in response to MyD88-dependent danger signals, including pathogen-associated molecular patterns (PAMPs) and host-derived damage associated molecular patterns (DAMPs). Danger signals also enhanced the secretion of IL-1β in response to toxins A and B, and subsequent IL-1 receptor signaling accounted for the majority of the increase in IL-23 that occurred in the presence of the toxins. Inhibition of inflammasome activation in the presence of extracellular K+likewise decreased IL-23 production. Finally, we found that IL-1β was increased in the serum of patients with CDI, suggesting that this systemic response could influence downstream production of pathogenic IL-23. Identification of the synergy of danger signals with toxins A and B via inflammasome signaling represents a novel finding in the mechanistic understanding of C. difficile-induced inflammation.

IMPORTANCEClostridium difficileis among the leading causes of death due to health care-associated infection, and factors determining disease severity are not well understood. C. difficile secretes toxins A and B, which cause inflammation and tissue damage, and recent findings suggest that some of this tissue damage may be due to an inappropriate host immune response. We have found that toxins A and B, in combination with both bacterium- and host-derived danger signals, can induce expression of the proinflammatory cytokines IL-1β and IL-23. Our results demonstrate that IL-1β signaling enhances IL-23 production and could lead to increased pathogenic inflammation during CDI.
A ventral incisional hernia with herniation of the left hepatic lobe and review of the literature
Authors: Neelamraju Lakshmi Harish , Saini Devendra , Om Prabha , Bagree Rajendra
Published: January 2015

Ventral incisional hernias with hepatic herniation are extremely rare. Only six cases have been reported so far in the literature. We report a case of a ventral incisional hernia with hepatic herniation along with a review of the literature. A 70-year-old female patient with a history of coronary artery bypass graft surgery 6 months earlier, was admitted to our hospital with symptoms of epigastric swelling and discomfort for 3 months. On examination, she had a mild tender 5 cm×5 cm epigastric lump and was diagnosed as ventral incisional hernia. Contrast-enhanced CT of the abdomen revealed a ventral hernia with herniation of omentum and left hepatic lobe. The patient underwent onlay mesh repair and is asymptomatic at 1-month follow-up. There is a need for evaluation of risk factors for this type of ventral incisional hernia and to recognise it as a special entity.
An unusual cause of stridor in an adult: mediastinal foregut duplication cyst
Authors: Wooles Nicola Rachel , Hoskison Emma , Elloy Marianne
Published: January 2015

We present a case of unusual presentation of stridor in an adult man who was identified to have a sudden expansion of a foregut duplication cyst in the mediastinum. This resulted in superior vena caval obstruction and subsequent airway compromise. Following resuscitation, the cyst was surgically removed via a thoracotomy which confirmed the diagnosis and provided definitive management. Foregut duplication cysts are an unusual cause of stridor in adults, with only five cases ever documented worldwide in the literature, presenting in such a manner. This case is a reminder of the importance of thorough clinical examination, the benefits of radiology as an indispensible adjunct and essential role of the multidisciplinary team.
Is schizophrenia associated with an increased risk of chronic kidney disease? A nationwide matched-cohort study
Authors: Tzeng Nian-Sheng , Hsu Yung-Ho , Ho Shinn-Ying , Kuo Yu-Ching , Lee Hua-Chin , Yin Yun-Ju , Chen Hong-An , Chen Wen-Liang , Chu William Cheng-Chung , Huang Hui-Ling
Published: January 2015

Objective

The impact of schizophrenia on vital diseases, such as chronic kidney disease (CKD), has not as yet been verified. This study aims to establish whether there is an association between schizophrenia and CKD.

Design

A nationwide matched cohort study.

Setting

Taiwan's National Health Insurance Research Database.

Participants

A total of 2338 patients with schizophrenia, and 7014 controls without schizophrenia (1:3), matched cohort for sex, age group, geography, urbanisation and monthly income, between 1 January 2003 and 31 December 2007, based on the International Classifications of Disease Ninth Edition (ICD-9), Clinical Modification codes.

Primary and secondary outcome measures

After making adjustments for confounding risk factors, a Cox proportional hazards model was used to compare the risk of developing CKD during a 3-year follow-up period from the index date.

Results

Of the 2338-subject case cohort, 163 (6.97%) developed a CKD, as did 365 (5.20%) of the 7014 control participants. Cox proportional hazards regression analysis revealed that patients with schizophrenia were more likely to develop CKD (HR=1.36, 95% CI 1.13 to 1.63; p<0.001). After adjusting for gender, age group, hypertension, diabetes mellitus, hyperlipidaemia, heart disease and non-steroid anti-inflammatory drugs (NSAIDs) usage, the HR for patients with schizophrenia was 1.25 (95% CI 1.04 to 1.50; p<0.05). Neither typical nor atypical antipsychotics was associated an increased risk of CKD in patients with schizophrenia.

Conclusions

The findings from this population-based retrospective cohort study suggest that schizophrenia is associated with a 25% increase in the risk of developing CKD within only a 3-year follow-up period.
Determination of three-dimensional shape of failure in soil slopes
Authors: Kalatehjari Roohollah , Arefnia Ali , A Rashid Ahmad Safuan , Ali Nazri , Hajihassani Mohsen
Published: January 2015

This paper presents the application of particle swarm optimization (PSO) in three-dimensional (3D) slope stability analysis to determine the shape and direction of failure as the critical slip surface. A detailed description of adopted PSO is presented and a rotating ellipsoidal shape is introduced as the possible failure surface in the analysis. Based on the limit equilibrium method, an equation of factor of safety (FoS) was developed with the ability to calculate the direction of sliding (DoS) in its internal process. A computer code was developed in Matlab to determine the 3D shape of the failure surface and calculate its FoS and DoS. Then, two example problems were used to verify the applicability of the presented code, the first by conducting a comparison between the results of the code and PLAXIS-3D finite element software and the second by re-analyzing an example from the literature to find the 3D failure surface. In addition, a hypothetical 3D asymmetric slope was introduced and analyzed to demonstrate the ability of the presented method to determine the shape and DOS of failure in 3D slope stability problems. Finally, a small-scale physical model of a 3D slope under vertical load was constructed and tested in the laboratory and the results were re-analyzed and compared with the code results. The results demonstrate the efficiency and effectiveness of the presented code in determining the 3D shape of the failure surface in soil slopes.
Cosmological models with the spinor and non-minimally interacting scalar field
Authors: Osetrin K. E. , Makarenko A. N. , Rybalov Yu. A.
Published: January 2015

The solution to the current extending Universe problem, and the description of all stages of evolution compels scientists to consider various cosmological models. Scalar–tensor models are rather simple and also allow us to clearly define the separate stages of evolution. Furthermore, other cosmological models are reduced. Our work takes into consideration the non-minimally interacted scalar field and the spinor field. The spinor field has been considered to establish a better understanding of the stages of evolution in our universe.
Hamiltonian analysis for Lifshitz type fields
Authors: Gaona Alejandro , Romero Juan M.
Published: January 2015

Using the Dirac method, we study the Hamiltonian consistency for three field theories. First, we study the electrodynamics a la Hořava and we show that this system is consistent for an arbitrary dynamical exponent z. Second, we study a Lifshitz type electrodynamics, which was proposed by Alexandre and Mavromatos [Phys. Rev. D 84, 105013 (2011)]. For this latter system we found that the canonical momentum and the electrical field are related through a Proca type Green function, however this system is consistent. In addition, we show that the anisotropic Yang–Mills theory with dynamical exponent z = 2 is consistent. Finally, we study a generalized anisotropic Yang–Mills theory and we show that this system is consistent too.
Temperature effects on excited state of strong-coupling polaron in an asymmetric RbCl quantum dot
Authors: Feng Li-Qin , Li Jing-Qi , Xiao Jing-Lin
Published: January 2015

On the condition of strong electron–LO phonon coupling in an asymmetric RbCl quantum dot (QD), the first excited state energy (FESE), the excitation energy (EE), and the transition frequency (TF) between the first excited ground states (FEGS) of the polaron are calculated by using the linear combination operator and the unitary transformation methods. The variation of the FESE, the EE and the TF with the temperature, the transverse and longitudinal confinement strengths (TLCS) of the QD are studied in detail. We find that the FESE, the EE and the TF decreases (increases) with increasing temperature when the temperature is in lower (higher) temperature regime. They are increasing functions of the TLCS. We find three ways to tune the FESE, the EE and the TF via controlling the temperature and the TLCS.
Magnetic properties of cobalt single layer added on graphene: A density functional theory study
Authors: Afshar M. , Doosti H.
Published: January 2015

In this paper, we have demonstrated magnetic ordering of single cobalt layer added on graphene using relativistic density functional theory at the level of generalized gradient approximation. We have shown that the single Co layer added on graphene show ferromagnetic ordering with perpendicular alignment to the graphene sheet. In the presence of spin-orbit coupling, a spin-polarization degree of about 92% was found for this quasi-two-dimensional magnetic system where it is shown a nearly half-metallic feature.
PEOPLE WATCH
Authors: Lim Rachel
Published: January 2015

Celebrating Innovation.
BIOMECHANICS OF CERVICAL SPINE FOLLOWING IMPLANTATION OF A SEMI-CONSTRAINED ARTIFICIAL DISC WITH UPWARD CENTER OF ROTATION: A FINITE ELEMENT INVESTIGATION
Authors: AKBARIAN D. , ROUHI G. , MASHHADI M. MOSAVI , HERZOG W.
Published: January 2015

The objective of this study was to evaluate the effects of a semi-constrained artificial disc with upward instantaneous center of rotation (ICR) on the biomechanics of the cervical spine. A three-dimensional nonlinear finite element model of the lower cervical spine (C4–C7) was developed using computed tomography (CT) data. The FE model was validated by comparing it to previously published experimental results for flexion-extension, lateral bending and axial rotation movements. The validated model was then altered to include prosthesis at the C5–C6 level. A hybrid test protocol was used to investigate the effects of total disc replacement. The results of this study showed that this artificial disc can help maintain the same range of motion (ROM) and intradiscal pressure as the intact model for most loading conditions. We also found that loads on the facet joints increased dramatically at index level. The capsular ligaments were also found to transmit more tension during flexion at implanted level. Although the artificial disc with upward ICR was found to restore normal kinematics, and prevented increases in intradiscal pressure, it was also associated with an overloading of the facet joints and capsular ligaments leading to potentially undesirable outcomes in the long term.
Area-Efficient Near-Associative Memories on FPGAs
Authors: Dhawan Udit , Dehon André
Published: January 2015

Associative memories can map sparsely used keys to values with low latency but can incur heavy area overheads. The lack of customized hardware for associative memories in today’s mainstream FPGAs exacerbates the overhead cost of building these memories using the fixed address match BRAMs. In this article, we develop a new, FPGA-friendly, memory system architecture based on a multiple hash scheme that is able to achieve near-associative performance without the area-delay overheads of a fully associative memory on FPGAs. At the same time, we develop a novel memory management algorithm that allows us to statistically mimic an associative memory. Using the proposed architecture as a 64KB L1 data cache, we show that it is able to achieve near-associative miss rates while consuming 3--13 × fewer FPGA memory resources for a set of benchmark programs from the SPEC CPU2006 suite than fully associative memories generated by the Xilinx Coregen tool. Benefits for our architecture increase with key width, allowing area reduction up to 100 ×. Mapping delay is also reduced to 3.7ns for a 1,024-entry flat version or 6.1ns for an area-efficient version compared to 17.6ns for a fully associative memory for a 64-bit key on a Xilinx Virtex 6 device.
Performance and Reliability Analysis of Cross-Layer Optimizations of NAND Flash Controllers
Authors: Bertozzi Davide , Carlo Stefano Di , Galfano Salvatore , Indaco Marco , Olivo Piero , Prinetto Paolo , Zambelli Cristian
Published: January 2015

NAND flash memories are becoming the predominant technology in the implementation of mass storage systems for both embedded and high-performance applications. However, when considering data and code storage in Non-Volatile Memories (NVMs), such as NAND flash memories, reliability and performance become a serious concern for systems designers. Designing NAND flash-based systems based on worst-case scenarios leads to waste of resources in terms of performance, power consumption, and storage capacity. This is clearly in contrast with the request for runtime reconfigurability, adaptivity, and resource optimization in modern computing systems. There is a clear trend toward supporting differentiated access modes in flash memory controllers, each one setting a differentiated tradeoff point in the performance-reliability optimization space. This is supported by the possibility of tuning the NAND flash memory performance, reliability, and power consumption through several tuning knobs such as the flash programming algorithm and the flash error correcting code. However, to successfully exploit these degrees of freedom, it is mandatory to clearly understand the effect that the combined tuning of these parameters has on the full NVM subsystem. This article performs a comprehensive quantitative analysis of the benefits provided by the runtime reconfigurability of an MLC NAND flash controller through the combined effect of an adaptable memory programming circuitry coupled with runtime adaptation of the ECC correction capability. The full NVM subsystem is taken into account, starting from a characterization of the low-level circuitry to the effect of the adaptation on a wide set of realistic benchmarks in order to provide readers a clear view of the benefit this combined adaptation may provide at the system level.
NCBI BLASTP on High-Performance Reconfigurable Computing Systems
Authors: Mahram Atabak , Herbordt Martin C.
Published: January 2015

The BLAST sequence alignment program is a central application in bioinformatics. The de facto standard version, NCBI BLAST, uses complex heuristics that make it challenging to simultaneously achieve both high performance and exact agreement. We propose a system that uses novel FPGA-based filters that reduce the input database by over 99.97% without loss of sensitivity. There are several contributions. First is design of the filters themselves, which perform two-hit seeding, exhaustive ungapped alignment, and exhaustive gapped alignments, respectively. Second is the coupling of the filters, especially the two-hit seeding and the ungapped alignment. Third is pipelining the filters in a single design, including maintaining load balancing as data are reduced by orders of magnitude at each stage. Fourth is the optimization required to maintain operating frequency for the resulting complex design. And finally, there is system integration both in hardware (the Convey HC1-EX) and software (NCBI BLASTP). We present results for various usage scenarios and find complete agreement and a factor of nearly 5x speedup over a fully parallel implementation of the reference code on a contemporaneous CPU. We believe that the resulting system is the leading per-socket-accelerated NCBI BLAST.
Resource-Aware Task Scheduling
Authors: Tillenius Martin , Larsson Elisabeth , Badia Rosa M. , Martorell Xavier
Published: January 2015

Dependency-aware task-based parallel programming models have proven to be successful for developing efficient application software for multicore-based computer architectures. The programming model is amenable to programmers, thereby supporting productivity, whereas hardware performance is achieved through a runtime system that dynamically schedules tasks onto cores in such a way that all dependencies are respected. However, even if the scheduling is completely successful with respect to load balancing, the scaling with the number of cores may be suboptimal due to resource contention. Here we consider the problem of scheduling tasks not only with respect to their interdependencies but also with respect to their usage of resources, such as memory and bandwidth. At the software level, this is achieved by user annotations of the task resource consumption. In the runtime system, the annotations are translated into scheduling constraints. Experimental results for different hardware, demonstrating performance gains both for model examples and real applications, are presented. Furthermore, we provide a set of tools to detect resource sensitivity and predict the performance improvements that can be achieved by resource-aware scheduling. These tools are solely based on parallel execution traces and require no instrumentation or modification of the application code.
Static Task Partitioning for Locked Caches in Multicore Real-Time Systems
Authors: Sarkar Abhik , Mueller Frank , Ramaprasad Harini
Published: January 2015

Growing processing demand on multitasking real-time systems can be met by employing scalable multicore architectures. For such environments, locking cache lines for hard real-time systems ensures timing predictability of data references and may lower worst-case execution time. This work studies the benefits of cache locking on massive multicore architectures with private caches in the context of hard real-time systems. In shared cache architectures, the cache is a single resource shared among
all
of the tasks. However, in scalable cache architectures with private caches, conflicts exist only among the tasks scheduled on one core. This calls for a cache-aware allocation of tasks onto cores.

The objective of this work is to increase the predictability of memory accesses resolved by caches while reducing the number of cores for a given task set. This allows designers to reduce the footprint of their subsystem of real-time tasks and thereby cost, either by choosing a product with fewer cores as a target or to allow more subsystems to be co-located on a given fixed number of cores.

Our work proposes a novel variant of the cache-unaware First Fit Decreasing (FFD) algorithm called Naive locked First Fit Decreasing (NFFD) policy. We propose two cache-aware static scheduling schemes: (a) Greedy First Fit Decreasing (GFFD) and (b) Colored First Fit Decreasing (CoFFD) for task sets where tasks do not have intratask conflicts among locked regions (Scenario A). NFFD is capable of scheduling high utilization task sets that FFD cannot schedule. Experiments also show that CoFFD consistently outperforms GFFD, resulting in a lower number of cores and lower system utilization. CoFFD reduces the number of core requirements by 30% to 60% compared to NFFD.

For a more generic case where tasks have intratask conflicts, we split the task partitioning between two phases: task selection and task allocation (Scenario B). Instead of resolving conflicts at a global level, these algorithms resolve conflicts among regions while allocating a task onto a core and unlocking at region level instead of task level. We show that a combination of dynamic ordering (task selection) with Chaitin’s Coloring (task allocation) scheme reduces the number of cores required by up to 22% over a basic scheme (in a combination of monotone ordering and regional FFD). Regional unlocking allows this scheme to outperform CoFFD for medium utilization task sets from Scenario A. However, CoFFD performs better than any other scheme for high utilization task sets from Scenario A. Overall, this work is unique in considering the challenges of future multicore architectures for real-time systems and provides key insights into task partitioning and cache-locking mechanisms for architectures with private caches.
Sponsored Search Auctions
Authors: Qin Tao , Chen Wei , Liu Tie-Yan
Published: January 2015

Sponsored search has been proven to be a successful business model, and sponsored search auctions have become a hot research direction. There have been many exciting advances in this field, especially in recent years, while at the same time, there are also many open problems waiting for us to resolve. In this article, we provide a comprehensive review of sponsored search auctions in hopes of helping both industry practitioners and academic researchers to become familiar with this field, to know the state of the art, and to identify future research topics. Specifically, we organize the article into two parts. In the first part, we review research works on sponsored search auctions with basic settings, where fully rational advertisers without budget constraints, preknown click-through rates (CTRs) without interdependence, and exact match between queries and keywords are assumed. Under these assumptions, we first introduce the generalized second price (GSP) auction, which is the most popularly used auction mechanism in the industry. Then we give the definitions of several well-studied equilibria and review the latest results on GSP’s efficiency and revenue in these equilibria. In the second part, we introduce some advanced topics on sponsored search auctions. In these advanced topics, one or more assumptions made in the basic settings are relaxed. For example, the CTR of an ad could be unknown and dependent on other ads; keywords could be broadly matched to queries before auctions are executed; and advertisers are not necessarily fully rational, could have budget constraints, and may prefer rich bidding languages. Given that the research on these advanced topics is still immature, in each section of the second part, we provide our opinions on how to make further advances, in addition to describing what has been done by researchers in the corresponding direction.
Does the Sharing of Execution Units Improve Performance/Power of Multicores?
Authors: Rodrigues Rance , Koren Israel , Kundu Sandip
Published: January 2015

Several studies and recent real-world designs have promoted sharing of underutilized resources between cores in a multicore processor to achieve better performance/power. It has been argued that when utilization of such resources is low, sharing has a negligible impact on performance while offering considerable area and power benefits. In this article, we investigate the performance and performance/watt implications of sharing large and underutilized resources between pairs of cores in a multicore. We first study sharing of the entire floating-point datapath (including reservation stations and execution units) by two cores, similar to AMD’s Bulldozer. We find that while this architecture results in power savings for certain workload combinations, it also results in significant performance loss of up to 28%. Next, we study an alternative sharing architecture where only the floating-point execution units are shared, while the individual cores retain their reservation stations. This reduces the highest performance loss to 14%. We then extend the study to include sharing of other large execution units that are used infrequently, namely, the integer multiply and divide units. Subsequently, we analyze the impact of sharing hardware resources in Simultaneously Multithreaded (SMT) processors where multiple threads run concurrently on the same core. We observe that sharing improves performance/watt at a negligible performance cost only if the shared units have high throughput. Sharing low-throughput units reduces both performance and performance/watt. To increase the throughput of the shared units, we propose the use of Dynamic Voltage and Frequency Boosting (DVFB) of only the shared units that can be placed on a separate voltage island. Our results indicate that the use of DVFB improves both performance and performance/watt by as much as 22% and 10%, respectively.
The Psi-Calculi Workbench
Authors: Borgstrom Johannes , Gutkovas Ramūnas , Rodhe Ioana , Victor Björn
Published: January 2015

Psi-calculi is a parametric framework for extensions of the pi-calculus with arbitrary data and logic. All instances of the framework inherit machine-checked proofs of the metatheory such as compositionality and bisimulation congruence. We present a generic analysis tool for psi-calculus instances, enabling symbolic execution and (bi)simulation checking for both unicast and broadcast communication. The tool also provides a library for implementing new psi-calculus instances. We provide examples from traditional communication protocols and wireless sensor networks. We also describe the theoretical foundations of the tool, including an improved symbolic operational semantics, with additional support for scoped broadcast communication.
Elastic Personalized Nonfunctional Attribute Preference and Trade-off Based Service Selection
Authors: Fletcher Kenneth K. , Liu Xiaoqing F. , Tang Mingdong
Published: January 2015

For service users to get the best service that meet their requirements, they prefer to personalize their nonfunctional attributes, such as reliability and price. However, the personalization makes it challenging for service providers to completely meet users’ preferences, because they have to deal with conflicting nonfunctional attributes when selecting services for users. With this in mind, users may sometimes want to explicitly specify their trade-offs among nonfunctional attributes to make their preferences known to service providers. In this article, we present a novel service selection method based on fuzzy logic that considers users’ personalized preferences and their trade-offs on nonfunctional attributes during service selection. The method allows users to represent their elastic nonfunctional requirements and associated importance using linguistic terms to specify their personalized trade-off strategies. We present examples showing how the service selection framework is used and a prototype with real-world airline services to evaluate the proposed framework's application.
The Scalable Commutativity Rule
Authors: Clements Austin T. , Kaashoek M. Frans , Zeldovich Nickolai , Morris Robert T. , Kohler Eddie
Published: January 2015

What opportunities for multicore scalability are latent in software interfaces, such as system call APIs? Can scalability challenges and opportunities be identified even before any implementation exists, simply by considering interface specifications? To answer these questions, we introduce the scalable commutativity rule:
whenever interface operations commute, they can be implemented in a way that scales.
This rule is useful throughout the development process for scalable multicore software, from the interface design through implementation, testing, and evaluation.

This article formalizes the scalable commutativity rule. This requires defining a novel form of commutativity,
SIM commutativity
, that lets the rule apply even to complex and highly stateful software interfaces.

We also introduce a suite of software development tools based on the rule. Our
Commuter
tool accepts high-level interface models, generates tests of interface operations that commute and hence could scale, and uses these tests to systematically evaluate the scalability of implementations. We apply
Commuter
to a model of 18 POSIX file and virtual memory system operations. Using the resulting 26,238 scalability tests,
Commuter
highlights Linux kernel problems previously observed to limit application scalability and identifies previously unknown bottlenecks that may be triggered by future workloads or hardware.

Finally, we apply the scalable commutativity rule and
Commuter
to the design and implementation sv6, a new POSIX-like operating system. sv6’s novel file and virtual memory system designs enable it to scale for 99% of the tests generated by
Commuter
. These results translate to linear scalability on an 80-core x86 machine for applications built on sv6’s commutative operations.