bluuebunny/crossref_metadata_2025 huggingface dataset:
Bacterial Resistance to Leucyl-tRNA Synthetase Inhibitor GSK2251052 Develops during Treatment of Complicated Urinary Tract Infections
Authors: O'Dwyer Karen , Spivak Aaron T. , Ingraham Karen , Min Sharon , Holmes David J. , Jakielaszek Charles , Rittenhouse Stephen , Kwan Alan L. , Livi George P. , Sathe Ganesh , Thomas Elizabeth , Van Horn Stephanie , Miller Linda A. , Twynholm Monique , Tomayko John , Dalessandro Marybeth , Caltabiano Madelyn , Scangarella-Oman Nicole E. , Brown James R.
Published: October 2014

GSK2251052, a novel leucyl-tRNA synthetase (LeuRS) inhibitor, was in development for the treatment of infections caused by multidrug-resistant Gram-negative pathogens. In a phase II study (study LRS114688) evaluating the efficacy of GSK2251052 in complicated urinary tract infections, resistance developed very rapidly in 3 of 14 subjects enrolled, with ≥32-fold increases in the GSK2251052 MIC of the infecting pathogen being detected. A fourth subject did not exhibit the development of resistance in the baseline pathogen but posttherapy did present with a different pathogen resistant to GSK2251052. Whole-genome DNA sequencing ofEscherichia coliisolates collected longitudinally from two study LRS114688 subjects confirmed that GSK2251052 resistance was due to specific mutations, selected on the first day of therapy, in the LeuRS editing domain. Phylogenetic analysis strongly suggested that resistantEscherichia coliisolates resulted from clonal expansion of baseline susceptible strains. This resistance development likely resulted from the confluence of multiple factors, of which only some can be assessed preclinically. Our study shows the challenges of developing antibiotics and the importance of clinical studies to evaluate their effect on disease pathogenesis. (These studies have been registered at ClinicalTrials.gov under registration no. NCT01381549 for the study of complicated urinary tract infections and registration no. NCT01381562 for the study of complicated intra-abdominal infections.)
A Hybrid Cationic Peptide Composed of Human β-Defensin-1 and Humanized θ-Defensin Sequences Exhibits Salt-Resistant Antimicrobial Activity
Authors: Olli Sudar , Nagaraj Ramakrishnan , Motukupally Swapna R.
Published: October 2014

We have designed a hybrid peptide by combining sequences of human β-defensin-1 (HBD-1) and θ-defensin, in an attempt to generate a molecule that combines the diversity in structure and biological activity of two different peptides to yield a promising therapeutic candidate. HBD-1 was chosen as it is a natural defensin of humans that is constitutively expressed, but its antibacterial activity is considerably impaired by elevated ionic strength. θ-Defensins are expressed in human bone marrow as a pseudogene and are homologous to rhesus monkey circular minidefensins. Retrocyclins are synthetic human θ-defensins. The cyclic nature of the θ-defensin peptides makes them salt resistant, nonhemolytic, and virtually noncytotoxic
in vitro
. However, a nonhuman circular molecule developed for clinical use would be less viable than a linear molecule. In this study, we have fused the C-terminal region of HBD-1 to the nonapeptide sequence of a synthetic retrocyclin. Cyclization was achieved by joining the terminal ends of the hybrid peptide by a disulfide bridge. The hybrid peptide with or without the disulfide bridge exhibited enhanced antimicrobial activity against both Gram-negative and Gram-positive bacteria as well as against fungi, including clinical bacterial isolates from eye infections. The peptide retained activity in the presence of NaCl and serum and was nonhemolytic
in vitro
. Thus, the hybrid peptide generated holds potential as a new class of antibiotics.
Anti-Alpha-Toxin Monoclonal Antibody and Antibiotic Combination Therapy Improves Disease Outcome and Accelerates Healing in a Staphylococcus aureus Dermonecrosis Model
Authors: Hilliard Jamese J. , Datta Vivekananda , Tkaczyk Christine , Hamilton Melissa , Sadowska Agnieszka , Jones-Nelson Omari , O'Day Terrence , Weiss William J. , Szarka Szabolcs , Nguyen Vien , Prokai Laszlo , Suzich JoAnn , Stover C. Kendall , Sellman Bret R.
Published: October 2014

Alpha-toxin (AT) is a major virulence determinant in
Staphylococcus aureus
skin and soft tissue infection models. We previously demonstrated that prophylactic administration of 2A3, an AT-neutralizing monoclonal antibody (MAb), prevents
S. aureus
disease in a mouse dermonecrosis model by neutralizing AT-mediated tissue necrosis and immune evasion. In the present study, MEDI4893*, an affinity-optimized version of 2A3, was characterized for therapeutic activity in the dermonecrosis model as a single agent and in combination with two frontline antibiotics, vancomycin and linezolid. MEDI4893* postinfection therapy was found to exhibit a therapeutic treatment window similar to that for linezolid but longer than that for vancomycin. Additionally, when combined with either vancomycin or linezolid, MEDI4893* resulted in reduced tissue damage, increased neutrophil and macrophage infiltration and abscess formation, and accelerated healing relative to those with the antibiotic monotherapies. These data suggest that AT neutralization with a potent MAb holds promise for both prophylaxis and adjunctive therapy with antibiotics and may be a valuable addition to currently available options for the treatment of
S. aureus
skin and soft tissue infections.
Activities of Antibiotic Combinations against Resistant Strains of Pseudomonas aeruginosa in a Model of Infected THP-1 Monocytes
Authors: Buyck Julien M. , Tulkens Paul M. , Van Bambeke Françoise
Published: October 2014

Antibiotic combinations are often used for treating
Pseudomonas aeruginosa
infections but their efficacy toward intracellular bacteria has not been investigated so far. We have studied combinations of representatives of the main antipseudomonal classes (ciprofloxacin, meropenem, tobramycin, and colistin) against intracellular
P. aeruginosa
in a model of THP-1 monocytes in comparison with bacteria growing in broth, using the reference strain PAO1 and two clinical isolates (resistant to ciprofloxacin and meropenem, respectively). Interaction between drugs was assessed by checkerboard titration (extracellular model only), by kill curves, and by using the fractional maximal effect (FME) method, which allows studying the effects of combinations when dose-effect relationships are not linear. For drugs used alone, simple sigmoidal functions could be fitted to all concentration-effect relationships (extracellular and intracellular bacteria), with static concentrations close to (ciprofloxacin, colistin, and meropenem) or slightly higher than (tobramycin) the MIC and with maximal efficacy reaching the limit of detection in broth but only a 1 to 1.5 (colistin, meropenem, and tobramycin) to 2 to 3 (ciprofloxacin) log
10
CFU decrease intracellularly. Extracellularly, all combinations proved additive by checkerboard titration but synergistic using the FME method and more bactericidal in kill curve assays. Intracellularly, all combinations proved additive only based on both FME and kill curve assays. Thus, although combinations appeared to modestly improve antibiotic activity against intracellular
P. aeruginosa
, they do not allow eradication of these persistent forms of infections. Combinations including ciprofloxacin were the most active (even against the ciprofloxacin-resistant strain), which is probably related to the fact this drug was the most effective alone intracellularly.
Evaluation of Antimalarial Resistance Marker Polymorphism in Returned Migrant Workers in China
Authors: Feng Jun , Li Jun , Yan He , Feng Xinyu , Xia Zhigui
Published: October 2014

Imported malaria has been a great challenge for public health in China due to decreased locally transmitted cases and frequent exchange worldwide.
Plasmodium falciparum
has been mainly responsible for the increasing impact. Currently, artesunate plus amodiaquine, one of the artemisinin combination therapies recommended by the World Health Organization, has been mainly used against uncomplicated
P. falciparum
malaria in China. However, drug resistance marker polymorphism in returning migrant workers has not been demonstrated. Here, we have evaluated the prevalence of
pfmdr1
and
pfcrt
polymorphisms, as well as the K13 propeller gene, a molecular marker of artemisinin resistance, in migrant workers returned from Ghana to Shanglin County, Guangxi Province, China, in 2013. A total of 118 blood samples were randomly selected and used for the assay. Mutations of the
pfmdr1
gene that covered codons 86, 184, 1034, and 1246 were found in 11 isolates. Mutations at codon N86Y (9.7%) were more frequent than at others, and Y
86
Y
184
S
1034
D
1246
was the most prevalent (63.6%) of the four haplotypes. Mutations of the
pfcrt
gene that covered codons 74, 75, and 76 were observed in 17 isolates, and M
74
N
75
T
76
was common (70.6%) in three haplotypes. Eight different genotypes of the K13 propeller were first observed in 10 samples in China, 2 synonymous mutations (V487V and A627A) and 6 nonsynonymous mutations. C580Y was the most prevalent (2.7%) in all the samples. The data presented might be helpful for enrichment of molecular surveillance of antimalarial resistance and will be useful for developing and updating antimalarial guidance in China.
The R262K Substitution Combined with H51Y in HIV-1 Subtype B Integrase Confers Low-Level Resistance against Dolutegravir
Authors: Cutillas Vincent , Mesplede Thibault , Anstett Kaitlin , Hassounah Said , Wainberg Mark A.
Published: October 2014

Clinical studies have shown that integrase strand transfer inhibitors (INSTIs) can be used effectively against HIV-1 infection. To date, no resistance substitution has been found in INSTI-naive patients treated with the new integrase inhibitor dolutegravir (DTG). In a recent selection study with DTG, using a virus bearing the H51Y substitution in integrase, the emergence of an R to K substitution at position 262 (R262K) was observed. We characterized this double mutant with respect to integrase strand transfer activity and susceptibility to DTG both biochemically and in tissue culture. We showed that the addition of R262K to H51Y decreased recombinant integrase strand transfer activity but improved integrase DNA-binding affinity, compared to wild-type or H51Y-containing enzymes. The defect in strand transfer activity did not translate into a decrease in HIV-1 infectivity. The combination of H51Y and R262K substitutions slightly decreased susceptibility to DTG (fold change = 1.87) in cell-based resistance assays. Although viral replication was not affected and enzyme efficiency was impaired by the addition of R262K to H51Y, there was an overall increase in the level of biochemical drug resistance against DTG. Our findings suggest that the R at position 262 plays an important role in DNA binding.
Intestinal Alkaline Phosphatase Deficiency Leads to Lipopolysaccharide Desensitization and Faster Weight Gain
Authors: Yang Ye , Millán José Luis , Mecsas Joan , Guillemin Karen
Published: October 2014

Animals develop in the presence of complex microbial communities, and early host responses to these microbes can influence key aspects of development, such as maturation of the immune system, in ways that impact adult physiology. We previously showed that the zebrafish intestinal alkaline phosphatase (ALPI) gene
alpi.1
was induced by Gram-negative bacterium-derived lipopolysaccharide (LPS), a process dependent on myeloid differentiation primary response gene 88 (MYD88), and functioned to detoxify LPS and prevent excessive host inflammatory responses to commensal microbiota in the newly colonized intestine. In the present study, we examined whether the regulation and function of ALPI were conserved in mammals. We found that among the mouse ALPI genes,
Akp3
was specifically upregulated by the microbiota, but through a mechanism independent of LPS or MYD88. We showed that disruption of
Akp3
did not significantly affect intestinal inflammatory responses to commensal microbiota or animal susceptibility to
Yersinia pseudotuberculosis
infection. However, we found that
Akp3
−/−
mice acquired LPS tolerance during postweaning development, suggesting that
Akp3
plays an important role in immune education. Finally, we demonstrated that inhibiting LPS sensing with a mutation in
CD14
abrogated the accelerated weight gain in
Akp3
−/−
mice receiving a high-fat diet, suggesting that the weight gain is caused by excessive LPS in
Akp3
−/−
mice.
Combinatorial Regulation of thedevOperon by MrpC2 and FruA during Myxococcus xanthus Development
Authors: Campbell Ashleigh , Viswanathan Poorna , Barrett Terry , Son Bongjun , Saha Shreya , Kroos Lee
Published: October 2014

Proper expression of thedevoperon is important for normal development ofMyxococcus xanthus. When starved, these bacteria coordinate their gliding movements to build mounds that become fruiting bodies as some cells differentiate into spores. Mutations in thedevTRSgenes impair sporulation. Expression of the operon occurs within nascent fruiting bodies and depends in part on C signaling. Here, we report that expression of thedevoperon, like that of several other C-signal-dependent genes, is subject to combinatorial control by the transcription factors MrpC2 and FruA. A DNA fragment upstream of thedevpromoter was bound by a protein in an extract containing MrpC2, protecting the region spanning positions −77 to −54. Mutations in this region impaired binding of purified MrpC2 and abolished developmental expression of reporter fusions. The association of MrpC2 and/or its longer form, MrpC, with thedevpromoter region depended on FruAin vivo, based on chromatin immunoprecipitation analysis, and purified FruA appeared to bind cooperatively with MrpC2 to DNA just upstream of thedevpromoterin vitro. We conclude that cooperative binding of the two proteins to this promoter-proximal site is crucial fordevexpression. 5′ deletion analysis implied a second upstream positive regulatory site, which corresponded to a site of weak cooperative binding of MrpC2 and FruA and boosteddevexpression 24 h into development. This site is unique among the C-signal-dependent genes studied so far. Deletion of this site in theM. xanthuschromosome did not impair sporulation under laboratory conditions.
First‐year student diary
Authors: Perrett Rosie
Published: October 2014

Rosie Perrett is moving to Liverpool today to begin her first year studying veterinary science, something that she says still hasn't really sunk in. Rosie is going to share her experiences with VR Careers.
Modeling of the thermohydromechanical–chemical response of Ontario sedimentary rocks to future glaciations
Authors: Nasir Othman , Fall Mamadou , Nguyen T. Son , Evgin Erman
Published: October 2014

In this work, the response of a proposed deep geological repository (DGR), located in sedimentary rock formations of southern Ontario, to potential future glaciation cycles is investigated numerically. A coupled thermohydromechanical–chemical model is developed and solved numerically by using the finite element method. The general circulation model (GCM) from the University of Toronto is used to generate future glacial cycles and related surface boundary conditions based on the past 120 000 years of glacial history. The geometry of the hypothetical DGR is adopted from the proposed design. Two types of vertical shaft conditions, effective and failed, are included and investigated in this study. For the case with effective vertical shafts, the results show that the potential radioactive solute transport is diffusion-dominated and the transport distance is contained within natural barriers. However, the results for the case of a shaft seal failure show that future glaciations could potentially lead to significant advection transport of radionuclides from the level of the DGR to the shallow ground water horizons. From a safety perspective, the shaft structure is concluded to be a critical part of the DGR system and needs to be considered as an important factor in safety assessments and future research.
Construction knowledge discovery system using fuzzy approach
Authors: Elwakil Emad , Zayed Tarek
Published: October 2014

Most research works in simulating construction operations have predominantly focused on modeling and mistreated data preparation that is paramount for simulation. To prepare data for simulation process, a knowledge discovery system (KDS) is indispensable in extracting hidden knowledge from construction data sets. This knowledge is typically hard to obtain using traditional means, such as statistical analysis. The presented research develops, using fuzzy approach, a KDS to prepare, utilize, analyze, and extract the hidden patterns from construction data to predict work task durations. The KDS depends mainly on finding the relation between quantitative and qualitative variables, which affect the duration of construction operations and work tasks as well as prepare data for simulation modeling. It consists of two stages: data processing and mining. Data processing consists of cleaning, integrating, transforming, and selecting the appropriate knowledge. Data mining consists of selecting the factors that affect a construction operation, generating their fuzzy sets, defining fuzzy rule and models, developing a fuzzy knowledge base, and testing the effectiveness of this knowledge base in predicting work task durations. The developed KDS has been tested using a construction case study in which the results found satisfactory with an average validity percent of 92%. The developed system assists researchers and practitioners in utilizing historical construction data to extract knowledge that could not be obtained by traditional techniques and precisely predicting work task durations.
Helicobacter pylori γ-glutamyl transpeptidase-induced Ca2+ release via PLC–IP3 receptors in AGS cells
Authors: Park Eun-Hee , Kim Jung-Min , Kim Kyung-Mi , Kang Dawon , Cho Young-Ah , Choi Jun-Young , Song Jea-Young , Kang Hyung-Lyun , Lee Woo-Kon , Cho Myung-Je , Rhee Kwang-Ho , Seo Ji-Hyun , Youn Hee-Shang , Baik Seung-Chul
Published: October 2014

In our previous study, γ-glutamyl transpeptidase (GGT) isolated from Helicobacter pylori induced apoptosis of AGS cells. Here, we investigate Ca2+ effects on GGT-induced apoptosis. The GGT transiently and significantly increased intracellular Ca2+ concentration ([Ca2+]i) in AGS cells in a dose-dependent manner (P < 0.05). The GGT-induced Ca2+ increase resulted from Ca2+ influx and release through the phospholipase C – inositol 1,4,5-trisphosphate (PLC–IP3) pathway. The GGT-induced apoptosis was significantly reduced by treatment with U73122 (a PLC inhibitor) and xestospongin (an IP3 receptor antagonist) (P < 0.05). These results indicate that GGT could induce apoptosis of AGS cells by high levels of [Ca2+]i.
2D isotropic negative permeability in a Λ-type three-level atomic system
Authors: Zhang Shuang-Ying , Gong Ai-Ling , Zhao Shun-Cai
Published: October 2014

An approach for two-dimensional (2D) negative permeability in a Λ-type three-level atomic system interacting with a magnetic probe and the superposition of two orthogonal standing-wave fields is proposed. Through theoretical analysis and numerical simulation, two equally and tunable peak maxima of negative magnetic responses are observed in the x-y plane, and around the peak maxima region the negative permeability is isotropic. A new avenue to 2D isotropic negative permeability in isotropic applications, via the quantum optics method, is achieved in our scheme.
AN ADAPTIVE HEURISTIC ALGORITHM WITH THE PROBABILISTIC SAFETY VECTOR FOR FAULT-TOLERANT ROUTING ON THE (n, k)-STAR GRAPH
Authors: CHIU CHIAO-WEI , HUANG KUO-SI , YANG CHANG-BIAU , TSENG CHIOU-TING
Published: October 2014

The (n, k)-star graph is a generalization of the n-star graph. It has better scalability than the n-star graph and holds some good properties compared with the hypercube. This paper focuses on the design of the fault-tolerant routing algorithm for the (n, k)-star graph. We adopt the idea of collecting the limited global information used for routing on the n-star graph to the (n, k)-star graph. In the preliminary version of this paper, we built the probabilistic safety vector (PSV) with modified cycle patterns and developed the routing algorithm to decide the fault-free routing path with the help of PSV. Afterwards, we observed that the routing performance of PSV gets worse as the percentage of fault nodes increases, especially it exceeds 25%. In order to improve the routing performance with more faulty nodes, an adaptive method of threshold assignment for the PSV is also proposed. The performance is judged by the average length of routing paths. Compared with distance first search and safety level, PSV with dynamic threshold gets the best performance in the simulations.
ONLINE SCHEDULING OF MIXED CPU-GPU JOBS
Authors: CHEN LIN , YE DESHI , ZHANG GUOCHUAN
Published: October 2014

We consider the online scheduling problem in a CPU-GPU cluster. In this problem there are two sets of processors, the CPU processors and the GPU processors. Each job has two distinct processing times, one for the CPU processor and the other for the GPU processor. Once a job is released, a decision should be made immediately about which processor it should be assigned to. The goal is to minimize the makespan, i.e., the largest completion time among all the processors. Such a problem could be seen as an intermediate model between the scheduling problem on identical machines and unrelated machines. We provide a 3.85-competitive online algorithm for this problem and show that no online algorithm exists with competitive ratio strictly less than 2. We also consider two special cases of this problem, the balanced case where the number of CPU processors equals to that of GPU processors, and the one-sided case where there is only one CPU or GPU processor. For the balanced case, we first provide a simple 3-competitive algorithm, and then a better algorithm with competitive ratio of 2.732 is derived. For the one-sided case, a 3-competitive algorithm is given.
Thermodynamic approach to field equations in Lovelock gravity and f(R) gravity revisited
Authors: Miao Yan-Gang , Yuan Fang-Fang , Zhang Zheng-Zheng
Published: October 2014

The first law of thermodynamics at black hole horizons is known to be obtainable from the gravitational field equations. A recent study claims that the contributions at inner horizons should be considered in order to give the conventional first law of black hole thermodynamics. Following this method, we revisit the thermodynamic aspects of field equations in the Lovelock gravity and f(R) gravity by focusing on two typical classes of charged black holes in the two theories.
PEOPLE WATCH
Authors: Lim Rachel
Published: October 2014

Looking into the Brain.
QMLE OF A STANDARD EXPONENTIAL ACD MODEL: ASYMPTOTIC DISTRIBUTION AND RESIDUAL CORRELATION
Authors: SIN CHOR-YIU
Published: October 2014

Since the seminal work by Engle and Russell, (1998), numerous studies have applied their standard/linear ACD(m,q) model (autoregressive conditional duration model of orders m and q) to fit the irregular spaced transaction data. Recently, Araichi et al. (2013) also applied the ACD model to claims in insurance. Many of these papers assume that the standardized error follows a standard exponential distribution. In this paper, we derive the asymptotic distribution of the quasi-maximum likelihood estimator (QMLE) when a standard exponential distribution is used. In other words, we provide robust standard errors for an ACD model. Applying this asymptotic theory, we then derive the asymptotic distribution of the corresponding residual autocorrelation.
StaRMAP---A Second Order Staggered Grid Method for Spherical Harmonics Moment Equations of Radiative Transfer
Authors: Seibold Benjamin , Frank Martin
Published: October 2014

We present a simple method to solve spherical harmonics moment systems, such as the the time-dependent
PN
and
SPN
equations, of radiative transfer. The method, which works for arbitrary moment order
N
, makes use of the specific coupling between the moments in the
PN
equations. This coupling naturally induces staggered grids in space and time, which in turn give rise to a canonical, second-order accurate finite difference scheme. While the scheme does not possess TVD or realizability limiters, its simplicity allows for a very efficient implementation in Matlab. We present several test cases, some of which demonstrate that the code solves problems with ten million degrees of freedom in space, angle, and time within a few seconds. The code for the numerical scheme, called StaRMAP (Staggered grid Radiation Moment Approximation), along with files for all presented test cases, can be downloaded so that all results can be reproduced by the reader.
A Parallel Sparse Direct Solver via Hierarchical DAG Scheduling
Authors: Kim Kyungjoo , Eijkhout Victor
Published: October 2014

We present a parallel sparse direct solver for multicore architectures based on Directed Acyclic Graph (DAG) scheduling. Recently, DAG scheduling has become popular in advanced Dense Linear Algebra libraries due to its efficient asynchronous parallel execution of tasks. However, its application to sparse matrix problems is more challenging as it has to deal with an enormous number of highly irregular tasks. This typically results in substantial scheduling overhead both in time and space, which causes overall parallel performance to be suboptimal. We describe a parallel solver based on two-level task parallelism: tasks are first generated from a parallel tree traversal on the assembly tree; next, those tasks are further refined by using
algorithms
-
by
-
blocks
to gain fine-grained parallelism. The resulting fine-grained tasks are asynchronously executed after their dependencies are analyzed. Our approach is distinct from others in that we adopt two-level task scheduling to mirror the two-level parallelism. As a result, we reduce scheduling overhead, and increase efficiency and flexibility. The proposed parallel sparse direct solver is evaluated for the particular problems arising from the
hp
-Finite Element Method where conventional sparse direct solvers do not scale well.
Using UML Modeling to Facilitate Three-Tier Architecture Projects in Software Engineering Courses
Authors: Mitra Sandeep
Published: October 2014

This article presents the use of a model-centric approach to facilitate software development projects conforming to the three-tier architecture in undergraduate software engineering courses. Many instructors intend that such projects create software applications for use by real-world customers. While it is important that the first version of these applications satisfy the customer by providing the functionality the customer expects and perform reliably and efficiently, it is equally important to be able to accommodate the customer's change requests over the period of the product's lifetime. The challenges in achieving these goals include the lack of real-world software development experience among the student developers and the fact that postdeployment change requests will almost certainly have to be handled by students who are not among the original developers. In this article, we describe how a model-centric approach using UML has been effective in enabling students to develop and maintain eight software applications for small businesses over a 9-year period. We discuss the characteristics of our modeling technique, which include the application of modeling patterns and quality check rules that enable students to create a model that can be clearly and consistently mapped to code. We also describe the nature of these mapping-to-code techniques, emphasizing how they reduce coupling among the implementation's classes. We then discuss our experiences in the classroom with these techniques, focusing on how we have improved our teaching over the years based on the analysis of student performance and feedback. Finally, we compare our approach to related work teaching modeling and the development and maintenance of code in software engineering courses with both extensive and minimal modeling.
Integrating Testing into Software Engineering Courses Supported by a Collaborative Learning Environment
Authors: Clarke Peter J. , Davis Debra , King Tariq M. , Pava Jairo , Jones Edward L.
Published: October 2014

As software becomes more ubiquitous and complex, the cost of software bugs continues to grow at a staggering rate. To remedy this situation, there needs to be major improvement in the knowledge and application of software validation techniques. Although there are several software validation techniques, software testing continues to be one of the most widely used in industry. The high demand for software engineers in the next decade has resulted in more software engineering (SE) courses being offered in academic institutions. However, due to the number of topics to be covered in SE courses, little or no attention is given to software testing, resulting in students entering industry with little or no testing experience.

We propose a minimally disruptive approach of integrating software testing into SE courses by providing students access to a collaborative learning environment containing learning materials on testing techniques and testing tools. In this article, we describe the learning environment and the studies conducted to measure the benefits accrued by students using the learning environment in the SE courses.
Hardware Fault Recovery for I/O Intensive Applications
Authors: Ramachandran Pradeep , Hari Siva Kumar Sastry , Li Manlap , Adve Sarita V.
Published: October 2014

With continued process scaling, the rate of hardware failures in commodity systems is increasing. Because these commodity systems are highly sensitive to cost, traditional solutions that employ heavy redundancy to handle such failures are no longer acceptable owing to their high associated costs.

Detecting such faults by identifying anomalous software execution and recovering through checkpoint-and-replay is emerging as a viable low-cost alternative for future commodity systems. An important but commonly ignored aspect of such solutions is ensuring that external outputs to the system are fault-free. The outputs must be delayed until the detectors guarantee this, influencing fault-free performance. The overheads for resiliency must thus be evaluated while taking these delays into consideration; prior work has largely ignored this relationship.

This article concerns recovery for I/O intensive applications from in-core faults. We present a strategy to buffer external outputs using dedicated hardware and show that checkpoint intervals previously considered as acceptable incur exorbitant overheads when hardware buffering is considered. We then present two techniques to reduce the checkpoint interval and demonstrate a practical solution that provides high resiliency while incurring low overheads.
Adoption of Bundled Services with Network Externalities and Correlated Affinities
Authors: Guérin Roch , de Oliveira Jaudelice C. , Weber Steven
Published: October 2014

The goal of this article is to develop a principled understanding of when it is beneficial to bundle technologies or services whose value is heavily dependent on the size of their user base, that is, exhibits positive exernalities. Of interest is how the joint distribution, and in particular the correlation, of the values users assign to components of a bundle affect its odds of success. The results offer insight and guidelines for deciding when bundling new Internet technologies or services can help improve their overall adoption. In particular, successful outcomes appear to require a minimum level of value correlation.

Categories and Subject Descriptors (2012): Networks -- Network Algorithms -- Network economics; Networks -- Network properties -- Network dynamics; Information systems -- Information systems applications -- Collaborative and social computing systems and tools; Security and privacy -- Human and societal aspects of security and privacy; Human-centered computing -- Collaborative and social computing theory, concepts and paradigms
Demand-Invariant Price Relationships and Market Outcomes in Competitive Private Commons
Authors: Kavurmacioglu Emir , Alanyali Murat , Starobinski David
Published: October 2014

We introduce a private commons model that consists of network providers who serve a fixed primary demand and strategically price to improve their revenues from an additional secondary demand. For
general
forms of secondary demand, we establish the existence and uniqueness of two characteristic prices: the break-even price and the market sharing price. We show that the market sharing price is
always
greater than the break-even price, leading to a price interval in which a provider is both profitable and willing to share the demand. Making use of this result, we give insight into the nature of market outcomes.
Approximation Algorithms for Secondary Spectrum Auctions
Authors: Hoefer Martin , Kesselheim Thomas , Vöcking Berthold
Published: October 2014

We study combinatorial auctions for secondary spectrum markets, where short-term communication licenses are sold to wireless nodes. Channels can be assigned to multiple bidders according to interference constraints captured by a conflict graph. We suggest a novel approach to such combinatorial auctions using a graph parameter called inductive independence number. We achieve good approximation results by showing that interference constraints for wireless networks imply a bounded inductive independence number. For example, in the physical model the factor becomes
O
(√
k
log
2
n
) for
n
bidders and
k
channels. Our algorithms can be turned into incentive-compatible mechanisms for bidders with arbitrary valuations.
Measurements of Soil Carbon Dioxide Emissions from Two Maize Agroecosystems at Harvest under Different Tillage Conditions
Authors: Giacomo Gerosa , Angelo Finco , Fabio Boschetti , Stefano Brenna , Riccardo Marzuoli
Published: October 2014

In this study a comparison of the soil CO2fluxes emitted from two maize (Zea maysL.) fields with the same soil type was performed. Each field was treated with a different tillage technique: conventional tillage (30 cm depth ploughing) and no-tillage. Measurements were performed in the Po Valley (Italy) from September to October 2012, covering both pre- and postharvesting conditions, by means of two identical systems based on automatic static soil chambers. Main results show that no-tillage technique caused higher CO2emissions than conventional tillage (on average 2.78 and 0.79 μmol CO2 m−2 s−1, resp.). This result is likely due to decomposition of the organic litter left on the ground of the no-tillage site and thus to an increased microbial and invertebrate respiration. On the other hand, fuel consumption of conventional tillage technique is greater than no-tillage consumptions. For these reasons this result cannot be taken as general. More investigations are needed to take into account all the emissions related to the field management cycle.
Elevational Patterns of Plant Richness in the Taibai Mountain, China
Authors: Tang Lili , Li Tanbao , Li Dengwu , Meng Xiaxia
Published: October 2014

The elevational distribution of plant diversity is a popular issue in ecology and biogeography, and several studies have examined the determinants behind plant diversity patterns. In this study, using published data of the local flora of Taibai Mountain, we explored the effects of spatial and climatic factors on plant species richness. We also evaluated Rapoport’s elevational rule by examining the relationship between elevational range size and midpoint. Species richness patterns were regressed against area, middle domain effect (MDE), mean annual temperature (MAT), and mean annual precipitation (MAP). The results showed that richness of overall plants, seed plants, bryophytes, and ferns all showed hump-shaped patterns along the elevational gradient, although the absolute elevation of richness peaks differed in different plant groups. Species richness of each plant group was all associated strongly with MAT and MAP. In addition to climatic factors, overall plants and seed plants were more related to area in linear regression models, while MDE was a powerful explanatory variable for bryophytes. Rapoport’s elevational rule on species richness was not supported. Our study suggests that a combined interaction of spatial and climatic factors influences the elevational patterns of plant species richness on Taibai Mountain, China.
Hemifacial Spasm and Neurovascular Compression
Authors: Lu Alex Y. , Yeung Jacky T. , Gerrard Jason L. , Michaelides Elias M. , Sekula Raymond F. , Bulsara Ketan R.
Published: October 2014

Hemifacial spasm (HFS) is characterized by involuntary unilateral contractions of the muscles innervated by the ipsilateral facial nerve, usually starting around the eyes before progressing inferiorly to the cheek, mouth, and neck. Its prevalence is 9.8 per 100,000 persons with an average age of onset of 44 years. The accepted pathophysiology of HFS suggests that it is a disease process of the nerve root entry zone of the facial nerve. HFS can be divided into two types: primary and secondary. Primary HFS is triggered by vascular compression whereas secondary HFS comprises all other causes of facial nerve damage. Clinical examination and imaging modalities such as electromyography (EMG) and magnetic resonance imaging (MRI) are useful to differentiate HFS from other facial movement disorders and for intraoperative planning. The standard medical management for HFS is botulinum neurotoxin (BoNT) injections, which provides low-risk but limited symptomatic relief. The only curative treatment for HFS is microvascular decompression (MVD), a surgical intervention that provides lasting symptomatic relief by reducing compression of the facial nerve root. With a low rate of complications such as hearing loss, MVD remains the treatment of choice for HFS patients as intraoperative technique and monitoring continue to improve.
Analysis of the Influence of Cracked Sleepers under Static Loading on Ballasted Railway Tracks
Authors: Montalbán Domingo Laura , Zamorano Martín Clara , Palenzuela Avilés Cristina , Real Herráiz Julia I.
Published: October 2014

The principal causes of cracking in prestressed concrete sleepers are the dynamic loads induced by track irregularities and imperfections in the wheel-rail contact and the in-phase and out-of-phase track resonances. The most affected points are the mid-span and rail-seat sections of the sleepers. Central and rail-seat crack detection require visual inspections, as legislation establishes, and involve sleepers’ renewal even though European Normative considers that thicknesses up to 0.5 mm do not imply an inadequate behaviour of the sleepers. For a better understanding of the phenomenon, the finite element method constitutes a useful tool to assess the effects of cracking from the point of view of structural behaviour in railway track structures. This paper intends to study how the cracks at central or rail-seat section in prestressed concrete sleepers influence the track behaviour under static loading. The track model considers three different sleeper models: uncracked, cracked at central section, and cracked at rail-seat section. These models were calibrated and validated using the frequencies of vibration of the first three bending modes obtained from an experimental modal analysis. The results show the insignificant influence of the central cracks and the notable effects of the rail-seat cracks regarding deflections and stresses.
Leclercia adecarboxylataBacteremia in a Patient with Ulcerative Colitis
Authors: Kashani Amir , Chitsazan Morteza , Che Kendrick , Garrison Roger C.
Published: October 2014

Patients with inflammatory bowel disease (IBD) are a high risk population for bacteremia. Derangement in the mucosal architecture of the gastrointestinal (GI) tract and frequent endoscopic interventions in immunocompromised individuals are considered primary causes. Isolation of opportunistic microorganisms from the bloodstream of IBD patients has been increasingly reported in recent years.Leclercia adecarboxylatais a ubiquitous, aerobic, motile, gram-negative bacillus. The human GI tract is known to harbor this rarely pathogenic microorganism. There are only a few case reports of bacteremia with this microorganism; the majority are either polymicrobial or associated with immunocompromised patients. We describe a case of monomicrobialL. adecarboxylatabacteremia in a 43-year-old female who presented with bloody diarrhea. Colonoscopy revealed diffuse colonic mucosal inflammation with numerous ulcers, and histopathology revealed crypt abscesses. Following an episode of rectal bleeding, two sets of blood cultures grewL. adecarboxylata, which was treated with intravenous ceftriaxone. After a complicated hospital course, she was eventually diagnosed with ulcerative colitis and enteropathic arthritis, treated with intravenous methylprednisolone, mesalamine, and infliximab which resulted in resolution of her symptoms. In our previously immunocompetent patient, derangement of the gut mucosal barrier was the likely cause of bacteremia, yet performing endoscopic intervention may have contributed to bacterial translocation.
Tug-of-War Injuries: A Case Report and Review of the Literature
Authors: Chotai Pranit N. , Abdelgawad Amr A.
Published: October 2014

We report a case of a 10-year-old boy presenting with radial nerve palsy due to injury during a tug-of-war game. Patient was managed nonoperatively and regained radial nerve function. Tug-of-war is a globally popular noncontact sport. Injuries during this game are inevitable and may range from simple sprains to life and limb threatening trauma. Combined hip and knee injuries and soft-tissue injuries involving the back are most frequent. Most injuries occur when tug-of-war was played in an informal setting and where the tug-of-war International Federation rules were less likely to be followed. Measures should be taken to increase the awareness about these safety rules and prevention of consequent injuries. Sports physicians, pediatricians, orthopedic surgeons, general physicians, and athletic trainers should be aware of potential injuries resulting from this game while caring for these athletes, so as to be well prepared for apt management of the injuries associated with TOW.
Two-Sided Annihilator Condition with Generalized Derivations on Multilinear Polynomials
Authors: De Filippis V. , Scudo G. , Sorrenti L.
Published: October 2014

LetRbe a prime ring of characteristic different from 2, with extended centroidC,Uits two-sided Utumi quotient ring,Fa nonzero generalized derivation ofR,f(x1,…,xn)a noncentral multilinear polynomial overCinnnoncommuting variables, anda,b∈Rsuch thata[F(f(r1,…,rn)),f(r1,…,rn)]b=0for anyr1,…,rn∈R. Then one of the following holds: (1)a=0; (2)b=0; (3) there existsλ∈Csuch thatF(x)=λx, for allx∈R; (4) there existq∈Uandλ∈Csuch thatF(x)=(q+λ)x+xq, for allx∈R, andf(x1,…,xn)2is central valued onR; (5) there existq∈Uandλ,μ∈Csuch thatF(x)=(q+λ)x+xq, for allx∈R, andaq=μa,qb=μb.
An Efficient Solution for Hierarchical Access Control Problem in Cloud Environment
Authors: He Bing-Zhe , Chen Chien-Ming , Wu Tsu-Yang , Sun Hung-Min
Published: October 2014

The time‐bound hierarchical key assignment scheme provides a cryptographic solution for the access control problem in distributed systems (e.g., Pay‐TV and cloud computing applications). Most time‐bound hierarchical key assignment schemes can be divided into two types: adopting tamper‐resistant devices and utilizing public values. Despite the fact that adopting tamper‐resistant devices can easily resist to collusion attacks, utilizing public values is much cheaper and more suitable for cloud environment. In this paper, we proposed a new time‐bound hierarchical key assignment scheme, which can effectively defeat the collusion attack. Besides, the proposed scheme utilizes public values instead of tamper‐resistant devices, which will restrict user’s convenience. Compared with the previous works, our scheme requires fewer public values and has better performance.
Agent-Based Model to Study and Quantify the Evolution Dynamics of Android Malware Infection
Authors: Alegre-Sanahuja Juan , Camacho Javier , Cortés López Juan Carlos , Santonja Francisco-José , Villanueva Micó Rafael Jacinto
Published: October 2014

In the last years the number of malware Apps that the users download to their devices has risen. In this paper, we propose an agent-based model to quantify the Android malware infection evolution, modeling the behavior of the users and the different markets where the users may download Apps. The model predicts the number of infected smartphones depending on the type of malware. Additionally, we will estimate the cost that the users should afford when the malware is in their devices. We will be able to analyze which part is more critical: the users, giving indiscriminate permissions to the Apps or not protecting their devices with antivirus software, or the Android platform, due to the vulnerabilities of the Android devices that permit their rooted. We focus on the community of Valencia, Spain, although the obtained results can be extrapolated to other places where the number of Android smartphones remains fairly stable.
The Effect of Different Parameters on the Development of Compressive Strength of Oil Palm Shell Geopolymer Concrete
Authors: Kupaei Ramin Hosseini , Alengaram U. Johnson , Jumaat Mohd Zamin
Published: October 2014

This paper presents the experimental results of an on-going research project on geopolymer lightweight concrete using two locally available waste materials—low calcium fly ash (FA) and oil palm shell (OPS)—as the binder and lightweight coarse aggregate, respectively. OPS was pretreated with three different alkaline solutions of sodium hydroxide (NaOH), potassium hydroxide, and sodium silicate as well as polyvinyl alcohol (PVA) for 30 days; afterwards, oil palm shell geopolymer lightweight concrete (OPSGPC) was cast by using both pretreated and untreated OPSs. The effect of these solutions on the water absorption of OPS, and the development of compressive strength in different curing conditions of OPSGPC produced by pretreated OPS were investigated; subsequently the influence of NaOH concentration, alkaline solution to FA ratio (A/FA), and different curing regimes on the compressive strength and density of OPSGPC produced by untreated OPS was inspected. The 24-hour water absorption value for OPS pretreated with 20% and 50% PVA solution was about 4% compared to 23% for untreated OPS. OPSGPC produced from OPS treated with 50% PVA solution produced the highest compressive strength of about 30 MPa in ambient cured condition. The pretreatment with alkaline solution did not have a significant positive effect on the water absorption of OPS aggregate and the compressive strength of OPSGPC. The result revealed that a maximum compressive strength of 32 MPa could be obtained at a temperature of 65°C and curing period of 4 days. This investigation also found that an A/FA ratio of 0.45 has the optimum amount of alkaline liquid and it resulted in the highest level of compressive strength.
Prediction of Three-Dimensional Milling Forces Based on Finite Element
Authors: Zhu Lida , Zhu Chunxia , Pei Jiaying , Li Xuebing , Wang Wei
Published: October 2014

The model of milling force is mainly proposed to predict and analyze the cutting process based on finite element method in this paper. Firstly, milling finite element model is given based on orthogonal cutting principle, and then the influence laws of cutting parameters on chip formation are analyzed by using different simulation parameters. In addition, the three-dimensional milling forces are obtained from finite element models. Finally, the values of milling force by the milling experiment are also compared and analyzed with the simulation values to verify the feasibility and reasonability. It can be shown that milling forces match well between simulation and experiment results, which can provide many good basic data and analysis methods to optimize the machining parameters, reduce tool wear, and improve the workpiece surface roughness and adapt to the programming strategy of high speed machining.