bluuebunny/crossref_metadata_2025 huggingface dataset:
A Condition Monitoring for Collapsing Bubble Mechanism for Sonoluminescence and Sonochemistry
Authors: Alhelfi Ali , Sundén Bengt
Published: January 2015

The acoustic cavitation phenomenon is a source of energy for a wide range of applications such as sonoluminescence and sonochemistry. The behavior of a single bubble in liquids is an essential study for acoustic cavitation. The bubbles react with the pressure forces in liquids and reveal their full potential when periodically driven by acoustic waves. As a result of extreme compression of the bubble oscillation in an acoustic field, the bubble produces a very high pressure and temperature during collapse. The temperature may increase many thousands of Kelvin, and the pressure may approach up to hundreds of bar. Subsequently, short flashes can be emitted (sonoluminescence) and the high local temperatures and pressures induce chemical reactions under extreme conditions (sonochemistry). Different models have been presented to describe the bubble dynamics in acoustic cavitation. These studies are done through full numerical simulation of the compressible Navier–Stokes equations. This task is very complex and consumes much computation time. Several features of the cavitation fields remain unexplained. In the current model, all hydrodynamics forces acting on the bubble are considered in the typical solution. Bubble oscillation and its characteristics under the action of a sound wave are presented in order to improve and give a more comprehensive understanding of the phenomenon, which is considered to have a significant role in different areas of science and technology.
Nanochannel fabrication based on double patterning with hydrogen silsesquioxane
Authors: Diest Kenneth , Goodman Russell , Rothschild Mordechai
Published: January 2015

A double patterning process is presented to pattern sub-35 nm wide channels in hydrogen silsesquioxane with near 100% pattern densities. Using aligned electron beam lithography, each side of the nanochannel structure is patterned as a separate layer. A 50 000 μC/cm2 high-dose anneal is applied to the first layer after exposure and develop to densify the structure and improve resistance to subsequent chemical exposure. Channels with widths below ∼60 nm are shown to exhibit footing with standard tetramethyl ammonium hydroxide developers. This problem is resolved by adding surfactant during the development of the final channel structure. The resulting process produced channels <35 nm wide with smooth sidewalls and a height of 45 nm.
13.2% efficiency double-hetero structure single-junction InGaAsN solar cells grown by MOVPE
Authors: Kim TaeWan , Mawst Luke J. , Kim Youngjo , Kim Kangho , Lee Jaejin , Kuech Thomas F.
Published: January 2015

Low background carbon concentration InGaAsN (Eg ∼ 1.18 eV), lattice-matched on a GaAs substrate, was grown at high temperatures (∼600 °C) using metalorganic vapor phase epitaxy. This material was used as an alternative to GaAs as the middle cell in triple-junction InGaP/GaAs/Ge solar cells. The low background carbon concentration (∼5 × 1016 cm−3) and increased depletion region width of the InGaAsN material significantly improves the solar cell performance over that found with dilute-nitride cells grown at lower growth temperatures (∼525 °C). The device performance of the solar cells with the low carbon InGaAsN active region yielded a short-circuit current density, open-circuit voltage, fill factor, and efficiency values of 26.05 mA/cm2, 0.67 V, 75.85%, and 13.2%, with antireflecting coating, respectively.
Therapeutic treasure hunt in the myeloid secretome
Authors: Erbay Ebru
Published: January 2015

Myeloid-derived growth-factor infusion might be superior to and safer than bone marrow cell transfusion in treating myocardial infarction.
Just keep breathing: How mitochondrial metabolism influences sepsis outcome
Authors: Serezani Henrique
Published: January 2015

UCP2 inhibition of fatty acid metabolism controls inflammasome activation and animal survival during polymicrobial sepsis.
Origins of Transcriptional Transition: Balance between Upstream and Downstream Regulatory Gene Sequences
Authors: Sala Adrien , Shoaib Muhammad , Anufrieva Olga , Mutharasu Gnanavel , Yli-Harja Olli , Kandhavelu Meenakshisundaram
Published: January 2015

By measuring individual mRNA production at the single-cell level, we investigated the
lac
promoter’s transcriptional transition during cell growth phases. In exponential phase, variation in transition rates generates two mixed phenotypes, low and high numbers of mRNAs, by modulating their burst frequency and sizes. Independent activation of the regulatory-gene sequence does not produce bimodal populations at the mRNA level, but bimodal populations are produced when the regulatory gene is activated coordinately with the upstream and downstream region promoter sequence (URS and DRS, respectively). Time-lapse microscopy of mRNAs for
lac
and a variant
lac
promoter confirm this observation. Activation of the URS/DRS elements of the promoter reveals a counterplay behavior during cell phases. The promoter transition rate coupled with cell phases determines the mRNA and transcriptional noise. We further show that bias in partitioning of RNA does not lead to phenotypic switching. Our results demonstrate that the balance between the URS and the DRS in transcriptional regulation determines population diversity.

IMPORTANCE
 By measuring individual mRNA production at the single-cell level, we investigated the
lac
promoter transcriptional transition during cell growth phases. In exponential phase, variation in transition rate generates two mixed phenotypes producing low and high numbers of mRNAs by modulating the burst frequency and size. Independent activation of the regulatory gene sequence does not produce bimodal populations at the mRNA level, while it does when activated together through the coordination of upstream/downstream promoter sequences (URS/DRS). Time-lapse microscopy of mRNAs for
lac
and a
lac
variant promoter confirm this observation. Activation of the URS/DRS elements of the promoter reveals a counterplay behavior during cell phases. The promoter transition rate coupled with cell phases determines the mRNA and transcriptional noise. We further show that bias in partitioning of RNA does not lead to phenotypic switching. Our results demonstrate that the balance between URS and DRS in transcription regulation is determining the population diversity.
The Lipid-Modifying Multiple Peptide Resistance Factor Is an Oligomer Consisting of Distinct Interacting Synthase and Flippase Subunits
Authors: Ernst Christoph M. , Kuhn Sebastian , Slavetinsky Christoph J. , Krismer Bernhard , Heilbronner Simon , Gekeler Cordula , Kraus Dirk , Wagner Samuel , Peschel Andreas
Published: January 2015

Phospholipids are synthesized at the inner leaflet of the bacterial cytoplasmic membrane but have to be translocated to the outer leaflet to maintain membrane lipid bilayer composition and structure. Even though phospholipid flippases have been proposed to exist in bacteria, only one such protein, MprF, has been described. MprF is a large integral membrane protein found in several prokaryotic phyla, whose C terminus modifies phosphatidylglycerol (PG), the most common bacterial phospholipid, with lysine or alanine to modulate the membrane surface charge and, as a consequence, confer resistance to cationic antimicrobial agents such as daptomycin. In addition, MprF is a flippase for the resulting lipids, Lys-PG or Ala-PG. Here we demonstrate that the flippase activity resides in the N-terminal 6 to 8 transmembrane segments of the
Staphylococcus aureus
MprF and that several conserved, charged amino acids and a proline residue are crucial for flippase function. MprF protects S. aureus against the membrane-active antibiotic daptomycin only when both domains are present, but the two parts do not need to be covalently linked and can function in
trans
. The Lys-PG synthase and flippase domains were each found to homo-oligomerize and also to interact with each other, which illustrates how the two functional domains may act together. Moreover, full-length MprF proteins formed oligomers, indicating that MprF functions as a dimer or larger oligomer. Together our data reveal how bacterial phospholipid flippases may function in the context of lipid biosynthetic processes.

IMPORTANCE
  Bacterial cytoplasmic membranes are crucial for maintaining and protecting cellular integrity. For instance, they have to cope with membrane-damaging agents such as cationic antimicrobial peptides (CAMPs) produced by competing bacteria (bacteriocins), secreted by eukaryotic host cells (defensins), or used as antimicrobial therapy (daptomycin). The MprF protein is found in many Gram-positive, Gram-negative, and even archaeal commensals or pathogens and confers resistance to CAMPs by modifying anionic phospholipids with amino acids, thereby compromising the membrane interaction of CAMPs. Here we describe how MprF does not only modify phospholipids but uses an additional, distinct domain for translocating the resulting lysinylated phospholipids to the outer leaflet of the membrane. We reveal critical details for the structure and function of MprF, the first dedicated prokaryotic phospholipid flippase, which may pave the way for targeting MprF with new antimicrobials that would not kill bacteria but sensitize them to antibiotics and innate host defense molecules.
Clinically led performance management in secondary healthcare: evaluating the attitudes of medical and non-clinical managers
Authors: Trebble Timothy M , Paul Maureen , Hockey Peter M , Heyworth Nicola , Humphrey Rachael , Powell Timothy , Clarke Nicholas
Published: January 2015

Introduction

Improving the quality and activity of clinicians’ practice improves patient care. Performance-related human resource management (HRM) is an established approach to improving individual practice but with limited use among clinicians. A framework for performance-related HRM was developed from successful practice in non-healthcare organisations centred on distributive leadership and locally provided, validated and interpreted performance measurement. This study evaluated the response of medical and non-clinical managers to its implementation into a large secondary healthcare organisation.

Methods

A semistructured qualitative questionnaire was developed from themes identified during framework implementation and included attitudes to previous approaches to measuring doctors’ performance, and the structure and response to implementation of the performance-related HRM framework. Responses were analysed through a process of data summarising and categorising.

Results

A total of 29, from an invited cohort of 31, medical and non-clinical managers from departmental to executive level were interviewed. Three themes were identified: (1) previous systems of managing clinical performance were considered to be ineffective due to insufficient empowerment of medical managers and poor quality of available performance data; (2) the implemented framework was considered to address these needs and was positively received by medical and non-clinical managers; (3) introduction of performance-related HRM required the involvement of the whole organisation to executive level and inclusion within organisational strategy, structure and training.

Conclusions

This study suggests that a performance-related HRM framework may facilitate the management of clinical performance in secondary healthcare, but is dependent on the design and methods of application used. Such approaches contrast with those currently proposed for clinicians in secondary healthcare in the UK and suggest that alternative strategies should be considered.
Identifying clusters of falls-related hospital admissions to inform population targets for prioritising falls prevention programmes
Authors: Finch Caroline F , Stephan Karen , Shee Anna Wong , Hill Keith , Haines Terry P , Clemson Lindy , Day Lesley
Published: January 2015

Background

There has been limited research investigating the relationship between injurious falls and hospital resource use. The aims of this study were to identify clusters of community-dwelling older people in the general population who are at increased risk of being admitted to hospital following a fall and how those clusters differed in their use of hospital resources.

Methods

Analysis of routinely collected hospital admissions data relating to 45 374 fall-related admissions in Victorian community-dwelling older adults aged ≥65 years that occurred during 2008/2009 to 2010/2011. Fall-related admission episodes were identified based on being admitted from a private residence to hospital with a principal diagnosis of injury (International Classification of Diseases (ICD)-10-AM codes S00 to T75) and having a first external cause of a fall (ICD-10-AM codes W00 to W19). A cluster analysis was performed to identify homogeneous groups using demographic details of patients and information on the presence of comorbidities. Hospital length of stay (LOS) was compared across clusters using competing risks regression.

Results

Clusters based on area of residence, demographic factors (age, gender, marital status, country of birth) and the presence of comorbidities were identified. Clusters representing hospitalised fallers with comorbidities were associated with longer LOS compared with other cluster groups. Clusters delineated by demographic factors were also associated with increased LOS.

Conclusions

All patients with comorbidity, and older women without comorbidities, stay in hospital longer following a fall and hence consume a disproportionate share of hospital resources. These findings have important implications for the targeting of falls prevention interventions for community-dwelling older people.
Force and aspiration analysis of the ADAPT technique in acute ischemic stroke treatment
Authors: Hu Yin C , Stiefel Michael F
Published: January 2015

Introduction

The development of new revascularization devices has significantly improved recanalization rates and time to reperfusion. A direct aspiration first-pass (ADAPT) technique for stroke thrombectomy was recently shown to be an effective and rapid way to achieve revascularization. The technique focuses on engaging and removing a clot without the use of a separator or retriever by relying on the force and aspiration generated by the catheter. We sought to compare the physical and fluid dynamic properties (force and aspiration) of commercially available catheters to determine the most effective catheter for the ADAPT technique.

Methods

Benchtop models were employed to compare aspiration for each catheter by submersing the catheter into a graduated cylinder and aspirating water. The volume of fluid aspirated and flow rates were calculated. Force of aspiration at the tip of each catheter was measured using a vacuum pressure gauge while the catheter was attached to a standard aspiration pump. Force was then calculated.

Results

The Penumbra 5MAX ACE catheter had the greatest aspiration rate of all the catheters at 245 mL/min. The Penumbra 5 MAX catheter aspirated 212 mL/min, followed by the Navien 058 and DAC 057 with 198 mL/min and 197 mL/min, respectively. The Penumbra 5MAX ACE generated the greatest tip force (18.25 g) and the 5MAX had the least amount of force (14.77 g).

Conclusions

The physical and fluid dynamic properties of currently available catheters suggest that the 5MAX ACE is the optimal catheter to use in direct aspiration for stroke therapy.
Short-term mortality of adult inpatients with community-acquired pneumonia: external validation of a modified CURB-65 score
Authors: Pflug Marc Andre , Tiutan Timothy , Wesemann Thomas , Nüllmann Harald , Heppner Hans Jürgen , Pientka Ludger , Thiem Ulrich
Published: January 2015

Objective

The management of community-acquired pneumonia (CAP) continues to be a challenge, especially in older people. To enable better risk stratification, a variation of the severity scores CRB-65 and CURB-65, called CURB-age, has been suggested. We compared the association between risk groups as defined by the scores and 30-day mortality for a cohort of mainly older inpatients with CAP.

Methods

We retrospectively analysed data from the CAP database from the years 2005 to 2009 of a single centre in Herne, Germany. Patient characteristics, criteria values within the severity scores CURB-65, CRB-65 and CURB-age, and 30-day mortality were assessed. We compared the association between score points and score-defined risk groups and mortality. Sensitivity and specificity with corresponding 95% CIs were calculated, and receiver operating characteristic (ROC) curve analysis was performed.

Results

Data from 559 patients were analysed (mean age 74.1 years, 55.3% male). Mortality at day 30 was 10.9%. CURB-age included more patients in the low-risk category than CRB-65 (195 vs 89), and the patient group had a lower mortality (2.6% vs 3.4%). When compared with CURB-65, CURB-age included slightly fewer patients (195 vs 214) with lower mortality (2.6% vs 4.2%). CURB-age sorted the most patients who died within 30 days into the high-risk CAP group (CURB-age, 32; CURB-65, 28; CRB-65, 9), which had the highest mortality (CURB-age, 26.4%; CURB-65, 19.4%; CRB-65, 21.4%). Advantages of CURB-age categories were depicted through ROC curve analysis (area under the curve 0.73 (95% CI 0.67 to 0.79) for CURB-age categories, 0.67 (95% CI 0.60 to 0.74) for CURB-65 categories, and 0.59 (95% CI 0.52 to 0.66) for CRB-65 categories).

Conclusions

In comparison with CRB-65 and CURB-65, risk stratification as defined by CURB-age showed the closest association with 30-day mortality in our sample. Further prospective studies are needed to assess the potential of CURB-age for better risk prediction, especially in older patients with CAP.
Surgical treatment of bilateral distal femoral Salter‐Harris type I fractures in a juvenile southern hairy‐nosed wombat
Authors: Anderson Gail I , Boardman Wayne Stuart John , Davies Sarah , McEwen Mary Margaret
Published: January 2015

We report a case of a 13‐month‐old 7.5 kg male hand‐raised orphaned southern hairy‐nosed wombat that presented with progressive hindlimb lameness and reluctance to move. Radiographs revealed bilateral distal femoral Salter‐Harris fractures with caudal displacement of the epiphyseal fragments. His hip radiographs exhibited some changes in his femoral capital epiphyses suggestive of epiphyseal dysplasia. Surgical correction of the position of the distal femoral epiphyses was performed bilaterally and their corrected position maintained using crossed Kirschner wires. He exhibited steady recovery over four months and was rehabilitated on a wombat sanctuary where he is active and apparently normal. We highlight this case to add to the limited resources available for this species as well as to comment on the mechanism of injury that was likely to have been forcible removal by his hindlimbs from his deceased mother's pouch.
Harvest control rules for mixed-stock fisheries coping with autocorrelated recruitment variation, conservation of weak stocks, and economic well-being
Authors: Hawkshaw Michael , Walters Carl
Published: January 2015

Dynamic programming is used to construct harvest control rules that account for persistent changes in productivity, exploitation rate constraints that prevent extinction of nontarget weak stocks, and an economic objective that recognizes moderate income to be more important to fishermen than maximization of total profit. Persistent productivity changes imply downward adjustment in spawning abundance targets during periods of low productivity, while conservation constraints simply imply upper limits on exploitation rate at high stock sizes. When the economic objective is to maximize the logarithm of net income (diminishing marginal utility or welfare from higher incomes), the optimum control rule shifts from a fixed escapement form to a curve where exploitation rate increases smoothly from zero at the minimum stock size that can be fished profitably to the upper limit set by a conservation constraint. This policy is not the fixed-exploitation rate form that has been historically suggested as a way of stabilizing harvests without major loss in profits. Application of harvest control rules constructed using dynamic programming in a mixed-stock salmon fishery in fact results in total profits close to those obtainable with fixed escapement policies but without the frequent low catches or closures implied by fixed escapement policies.
Parametrization of Pontecorvo–Maki–Nakagawa–Sakata mixing matrix based on CP-violating bipair neutrino mixing
Authors: Iizuka Jun , Kitabayashi Teruyuki , Minagawa Yuki , Yasuè Masaki
Published: January 2015

CP violation in neutrino interactions is described by three phases contained in Pontecorvo–Maki–Nakagawa–Sakata mixing matrix (U PMNS ). We argue that the phenomenologically consistent result of the Dirac CP violation can be obtained if U PMNS is constructed along bipair neutrino mixing scheme, namely, requiring that |U12| = |U32| and |U22| = |U23| (case 1) and |U12| = |U22| and |U32| = |U33| (case 2), where Uij stands for the i × j matrix element of U PMNS . As a result, the solar, atmospheric and reactor neutrino mixing angles θ12, θ23 and θ13, respectively, are correlated to satisfy cos 2θ12 = sin 2 θ23 - tan 2 θ13 (case 1) or cos 2θ12 = cos 2 θ23 - tan 2 θ13 (case 2). Furthermore, if Dirac CP violation is observed to be maximal, θ23 is determined by θ13 to be: [Formula: see text] (case 1) or [Formula: see text] (case 2). For the case of non-maximal Dirac CP violation, we perform numerical computation to show relations between the CP-violating Dirac phase and the mixing angles.
Accelerating black holes, spin-$\frac32$ fields and C-metric
Authors: Lin Hai , Saifullah K. , Yau Shing-Tung
Published: January 2015

We consider spin-[Formula: see text] particles on the background of general accelerating black holes and the C-metric. The Rarita–Schwinger equations of spin-[Formula: see text] particles are analyzed on these backgrounds. The emission and absorption probabilities of these particles on these spacetimes are calculated. These backgrounds which we analyze contain both black hole horizon and acceleration horizon, and have general electric and magnetic charges, rotation, and acceleration parameter. Other physical quantities of the spin-[Formula: see text] field near the acceleration horizon are also computed.
Combinatorics of link diagrams and volume
Authors: Giambrone Adam
Published: January 2015

We show that the volumes of certain hyperbolic A-adequate links can be bounded (above and) below in terms of two diagrammatic quantities: the twist number and the number of certain alternating tangles in an A-adequate diagram. We then restrict our attention to plat closures of certain braids, a rich family of links whose volumes can be bounded in terms of the twist number alone. Furthermore, in the absence of special tangles, our volume bounds can be expressed in terms of a single stable coefficient of the colored Jones polynomial. Consequently, we are able to provide a new collection of links that satisfy a Coarse Volume Conjecture.
Nonlinear optical absorption of a two electron GaN/AlN constant total effective radius multi-shells quantum rings
Authors: Solaimani M.
Published: January 2015

In this paper, we have investigated the effect of the well number and quantum ring thickness on subband energies, intersubband transition energy and linear and nonlinear optical properties of a two electron GaN / AlN constant total effective radius multi-shells quantum rings (CTER-MSQRs). Effect of well number increase on linear and third order absorption coefficients and refractive index changes is not monotonic, while if inner ring radius R0 increases absorption coefficient monotonically decreases. Absorption peak positions have no red/blueshifts when well number or inner quantum ring radius R0 increase. When well number increases, the amount of nonlinearity monotonically decreases. Finally, six-wells CTER-MSQR has minimum nonlinearity.
Transient spectrum of sin2-pulsed driven harmonic oscillator
Authors: Hassan S. S. , Alharbey R. A. , Al-Zaki H.
Published: January 2015

Exact analytical results are derived for the coupled system of nondissipative single mode quantized harmonic oscillator (HO) and arbitrary pulse shape. Specifically, for a sin2-pulse shape, the transient fluorescent spectrum is obtained in the general case of initial coherent state |α〉 of the HO. The dominant central Lorentzian is surrounded by weak oscillations due to the larger number of sequential pulses which get amplified asymmetrically in the nonresonant case as a result of balancing and interference processes between the initial excitation (|α2|) and the strength of the exciting pulse. Further pronounced oscillations is noticed with "hole burning" structure in the central peak due to nonzero phase of the initial amplitude (α).
NANOMECHANICAL CHARACTERIZATION OF ZIRCONIA THIN FILMS DEPOSITED ON UHMWPE BY PULSED PLASMA DEPOSITION
Authors: BIANCHI MICHELE , BOI MARCO , LOPOMO NICOLA , MALTARELLO MARIA CRISTINA , LISCIO FABIOLA , MILITA SILVIA , VISANI ANDREA , RUSSO ALESSANDRO , MARCACCI MAURILIO
Published: January 2015

Plastic deformation and wear of the ultra-high molecular weight polyethylene (UHMWPE) insert have been pointed out as major issues relating to the long-term stability of an orthopaedic implant. The deposition of protective hard, tough and well-adhered zirconia ( ZrO2) thin films directly on the surface of the UHMWPE component via the Pulsed Plasma Deposition (PPD) technique has been already demonstrated to be a feasible way to approach this problem. In the current study, the tribo-mechanical properties of ZrO2-coated UHMWPE with respect to pristine UHMWPE were investigated in detail. Specifically, strength to local plastic deformation, indentation work portioning and creep behavior were evaluated through nanoindentation and micro-scratch tests. Further, preliminary wear data (i.e., rate and volume) were obtained by tribology tests mating coated and pristine UHMWPE with an alumina ball under dry conditions. The results of the mechanical tests evidenced a strong reduction of plastic deformation under both normal and tangential local loads and a drop of the 80% of the creep phenomenon for coated UHMWPE compared to pristine UHMWPE. Despite tribological tests showed similar wear data for coated and pristine UHMWPE, a different wear mechanism was detected between the two groups. The reported results supported the possibility to pursue this novel approach of depositing ZrO2thin film to protect the UHWMPE insert and enhance the long-term stability of the orthopaedic implants.
ADOMIAN DECOMPOSITION METHOD (ADM) SIMULATION OF MAGNETO-BIO-TRIBOLOGICAL SQUEEZE FILM WITH MAGNETIC INDUCTION EFFECTS
Authors: BÉG O. ANWAR , TRIPATHI D. , SOCHI T. , GUPTA P. K.
Published: January 2015

The Adomian decomposition method (ADM) is applied to analyze Newtonian bio-magneto-tribological squeeze film flow with magnetic induction effects incorporated. Robust solutions are developed for the transformed radial and tangential momentum and radial and tangential induced magnetic field conservation equations. The effects of squeeze Reynolds number (N1= Rem/ Bt where Bt = Batchelor number), dimensionless axial magnetic force strength parameter (N2), dimensionless tangential magnetic force strength parameter (N3), magnetic Reynolds number ( Rem) are depicted graphically. ADM is observed to demonstrate excellent convergence, stability and versatility in simulating both magnetic squeeze film problems. Numerical verification is achieved with Nakamura's tridiagonal finite difference method (NTM). The simulations are relevant to "smart" biological bearings and prosthetics (e.g., "smart knees") exploiting magnetic fluids.
Energy-Efficient Thread Assignment Optimization for Heterogeneous Multicore Systems
Authors: Petrucci Vinicius , Loques Orlando , Mossé Daniel , Melhem Rami , Gazala Neven Abou , Gobriel Sameh
Published: January 2015

The current trend to move from homogeneous to heterogeneous multicore systems provides compelling opportunities for achieving performance and energy efficiency goals. Running multiple threads in multicore systems poses challenges on meeting limited shared resources, such as memory bandwidth. We propose an optimization approach that includes an Integer Linear Programming (ILP) optimization model and a scheme to dynamically determine thread-to-core assignment. We present simulation analysis that shows energy savings and performance gains for a variety of workloads compared to state-of-the-art schemes. We implemented and evaluated a prototype of our thread assignment approach at user level, leveraging Linux scheduling and performance-monitoring capabilities.
Complications with Complexity in Requirements
Authors: King John Leslie , Simon Carl P.
Published: January 2015

Requirements engineering must recognize the difference between complicated and complex problems. The former can lead to successful solutions. The latter should be avoided because they often lead to failure. As a starting point for distinguishing between complicated and complex, this article offers six characteristics of complex problems, with examples from economics, logistics, forecasting, among others. These characteristics make it easier and more systematic to recognize complexity during requirements elicitation and formulation.
Process Mining for Clinical Processes
Authors: Partington Andrew , Wynn Moe , Suriadi Suriadi , Ouyang Chun , Karnon Jonathan
Published: January 2015

Business process analysis and process mining, particularly within the health care domain, remain under-utilized. Applied research that employs such techniques to routinely collected health care data enables stakeholders to empirically investigate care as it is delivered by different health providers. However, cross-organizational mining and the comparative analysis of processes present a set of unique challenges in terms of ensuring population and activity comparability, visualizing the mined models, and interpreting the results. Without addressing these issues, health providers will find it difficult to use process mining insights, and the potential benefits of evidence-based process improvement within health will remain unrealized. In this article, we present a brief introduction on the nature of health care processes, a review of process mining in health literature, and a case study conducted to explore and learn how health care data and cross-organizational comparisons with process-mining techniques may be approached. The case study applies process-mining techniques to administrative and clinical data for patients who present with chest pain symptoms at one of four public hospitals in South Australia. We demonstrate an approach that provides detailed insights into clinical (quality of patient health) and fiscal (hospital budget) pressures in the delivery of health care. We conclude by discussing the key lessons learned from our experience in conducting business process analysis and process mining based on the data from four different hospitals.
A Hardware Framework for Yield and Reliability Enhancement in Chip Multiprocessors
Authors: Pan Abhisek , Rodrigues Rance , Kundu Sandip
Published: January 2015

Device reliability and manufacturability have emerged as dominant concerns in end-of-road CMOS devices. An increasing number of hardware failures are attributed to manufacturability or reliability problems. Maintaining an acceptable manufacturing yield for chips containing tens of billions of transistors with wide variations in device parameters has been identified as a great challenge. Additionally, today’s nanometer scale devices suffer from accelerated aging effects because of the extreme operating temperature and electric fields they are subjected to. Unless addressed in design, aging-related defects can significantly reduce the lifetime of a product. In this article, we investigate a micro-architectural scheme for improving yield and reliability of homogeneous chip multiprocessors (CMPs). The proposed solution involves a hardware framework that enables us to utilize the redundancies inherent in a multicore system to keep the system operational in the face of partial failures. A micro-architectural modification allows a faulty core in a CMP to use another core’s resources to service any instruction that the former cannot execute correctly by itself. This service improves yield and reliability but may cause loss of performance. The target platform for quantitative evaluation of performance under degradation is a dual-core and a quad-core chip multiprocessor with one or more cores sustaining partial failure. Simulation studies indicate that when a large, high-latency, and sparingly used unit such as a floating-point unit fails in a core, correct execution may be sustained through outsourcing with at most a 16% impact on performance for a floating-point intensive application. For applications with moderate floating-point load, the degradation is insignificant. The performance impact may be mitigated even further by judicious selection of the cores to commandeer depending on the current load on each of the candidate cores. The area overhead is also negligible due to resource reuse.
The Next 700 BFT Protocols
Authors: Aublin Pierre-Louis , Guerraoui Rachid , Knežević Nikola , Quéma Vivien , Vukolić Marko
Published: January 2015

We present Abstract (ABortable STate mAChine replicaTion), a new abstraction for designing and reconfiguring generalized replicated state machines that are, unlike traditional state machines, allowed to
abort
executing a client’s request if “something goes wrong.”

Abstract can be used to considerably simplify the incremental development of efficient Byzantine fault-tolerant state machine replication (
BFT
) protocols that are notorious for being difficult to develop. In short, we treat a
BFT
protocol as a composition of Abstract instances. Each instance is developed and analyzed independently and optimized for specific system conditions. We illustrate the power of Abstract through several interesting examples.

We first show how Abstract can yield benefits of a state-of-the-art
BFT
protocol in a less painful and error-prone manner. Namely, we develop
AZyzzyva
, a new protocol that mimics the celebrated best-case behavior of Zyzzyva using less than 35% of the Zyzzyva code. To cover worst-case situations, our abstraction enables one to use in
AZyzzyva
any existing
BFT
protocol.

We then present
Aliph
, a new
BFT
protocol that outperforms previous
BFT
protocols in terms of both latency (by up to 360%) and throughput (by up to 30%). Finally, we present
R-Aliph
, an implementation of
Aliph
that is
robust
, that is, whose performance degrades gracefully in the presence of Byzantine replicas and Byzantine clients.
A Brief Comment on “A Complete Self-Testing and Self-Configuring NoC Infrastructure for Cost-Effective MPSoCs” [ACM Transactions on Embedded Computing Systems 12 (2013) Article 106]
Authors: Bishnoi Rimpy , Laxmi Vijay , Gaur Manoj Singh , Flich José , Triviño Francisco
Published: January 2015

In the Ghiribaldi et al. [2013] paper, a complete self-testing and self configuring NoC infrastructure for cost-effective MPSoCs was presented in order to make NoC architecture tolerant to faults. To overcome the complexity involved during the complete reconfiguration of routing instances in the face of most of the usual failure patterns, Ghiribaldi et al. [2013] proposed a fast self-reconfiguration algorithm. The algorithm is based on segment-based routing implemented using Logic-Based Distributed Routing (LBDR) and claimed to have handled the most common NoC faults.

The purpose of this comment is to demonstrate the inconsistency of the fast self-configuration method presented in Ghiribaldi et al. [2013]. To handle inconsistency, we present the correct set of LBDR bits and also argue that complete reconfiguration of the routing instance is mandatory to handle some fault combinations. New coverage results of the fast self-reconfiguration algorithm of Ghiribaldi et al. [2013] are also presented.
Maximal Synthesis for Hennessy-Milner Logic
Authors: Hulst A. C. Van , Reniers M. A. , Fokkink W. J.
Published: January 2015

This article concerns the maximal synthesis for Hennessy-Milner Logic on Kripke structures with labeled transitions. We formally define, and prove the validity of, a theoretical framework that modifies a Kripke model to the least possible extent in order to satisfy a given HML formula. Applications of this work can be found in the field of controller synthesis and supervisory control for discrete-event systems. Synthesis is realized technically by first projecting the given Kripke model onto a bisimulation-equivalent partial tree representation, thereby unfolding up to the depth of the synthesized formula. Operational rules then define the required adaptations upon this structure in order to achieve validity of the synthesized formula. Synthesis might result in multiple valid adaptations, which are all related to the original model via simulation. Each simulant of the original Kripke model, which satisfies the synthesized formula, is also related to one of the synthesis results via simulation. This indicates maximality, or maximal permissiveness, in the context of supervisory control. In addition to the formal construction of synthesis as presented in this article, we present it in algorithmic form and analyze its computational complexity. Computer-verified proofs for two important theorems in this article have been created using the Coq proof assistant.
Active Learning for Web Search Ranking via Noise Injection
Authors: Cai Wenbin , Zhang Muhan , Zhang Ya
Published: January 2015

Learning to rank has become increasingly important for many information retrieval applications. To reduce the labeling cost at training data preparation, many active sampling algorithms have been proposed. In this article, we propose a novel active learning-for-ranking strategy called ranking-based sensitivity sampling (RSS), which is tailored for Gradient Boosting Decision Tree (GBDT), a machine-learned ranking method widely used in practice by major commercial search engines for ranking. We leverage the property of GBDT that samples close to the decision boundary tend to be sensitive to perturbations and design the active learning strategy accordingly. We further theoretically analyze the proposed strategy by exploring the connection between the sensitivity used for sample selection and model regularization to provide a potentially theoretical guarantee w.r.t. the generalization capability. Considering that the performance metrics of ranking overweight the top-ranked items, item rank is incorporated into the selection function. In addition, we generalize the proposed technique to several other base learners to show its potential applicability in a wide variety of applications. Substantial experimental results on both the benchmark dataset and a real-world dataset have demonstrated that our proposed active learning strategy is highly effective in selecting the most informative examples.
Apt
Authors: Ricci Robert , Wong Gary , Stoller Leigh , Webb Kirk , Duerig Jonathon , Downie Keith , Hibler Mike
Published: January 2015

Repeating research in computer science requires more than just code and data: it requires an appropriate environment in which to run experiments. In some cases, this environment appears fairly straightforward: it consists of a particular operating system and set of required libraries. In many cases, however, it is considerably more complex: the execution environment may be an entire network, may involve complex and fragile configuration of the dependencies, or may require large amounts of resources in terms of computation cycles, network bandwidth, or storage. Even the "straightforward" case turns out to be surprisingly intricate: there may be explicit or hidden dependencies on compilers, kernel quirks, details of the ISA, etc. The result is that when one tries to repeat published results, creating an environment sufficiently similar to one in which the experiment was originally run can be troublesome; this problem only gets worse as time passes. What the computer science community needs, then, are environments that have the explicit goal of enabling repeatable research. This paper outlines the problem of repeatable research environments, presents a set of requirements for such environments, and describes one facility that attempts to address them.
On Data Placement in Distributed Systems
Authors: Paiva João , Rodrigues Luís
Published: January 2015

Data placement refers to the problem of deciding how to assign data items to nodes in a distributed system to optimize one or several of a number of performance criteria such as reducing network congestion, improving load balancing, among others. This document reports on our experience when addressing this problem in distributed systems of different scales, namely: medium size datacenter-scale and internet-scale systems.
A heuristic approach to solve the elementary sprint optimization problem for non-cross-functional teams in Scrum
Authors: Sobiech Fabian , Eilermann Beate , Rausch Andreas
Published: January 2015

One goal of Scrum is to deliver as much added value as possible for the customer at the end of an iteration but in an environment with multiple different customers and stakeholders the definition of value varies. Therefore we defined the concept of value in the context of an OEM in the automotive industry for management information systems. We identified seven relevant value dimensions in a first case study and in a second case study we investigated the relation between the seven different value dimensions. Afterwards we define an optimal iteration based on our value definition for multiple non-cross-functional teams and show that this problem is a NP-hard problem. Finally we present a heuristic approach to solve this problem.
A light-weight compression method for Java card technology
Authors: Zilli Massimiliano , Raschke Wolfgang , Weiss Reinhold , Steger Christian , Loinig Johannes
Published: January 2015

Java Card is a Java running environment tailored for smart cards. In such small systems, resources are limited, and keeping application size as small as possible is a first order issue. Dictionary compression is a promising technique taken into consideration by several authors. The main drawback of this technique is a degradation in the execution speed.

In this paper we propose combining the dictionary compression with another compression technique based on the folding mechanism; the latter is less effective in terms of space savings, but has the advantage of speeding up the execution. A combination of the two techniques leads to higher space savings with a very low decrease in execution time compared with the plain dictionary compression.
Adaptive resource synchronization in hierarchical real-time systems
Authors: Springer Tom , Peter Steffen , Givargis Tony
Published: January 2015

In this paper we outline the Adaptive Resource Allocation Protocol (ARAP) as an improved resource synchronization algorithm for hierarchically scheduled real-time systems. ARAP exploits knowledge about task utilization, using a proportional-integral-derivative (PID) controller, to estimate required resource bandwidth and improve scheduling decisions. Our analysis and experiments with RTSIM show that ARAP provides better temporal isolation and resource utilization during periods of transient overload compared to state-of-the-art resource synchronization algorithms. Implemented as part of
VxWorks
, the results are confirmed using an avionic system, for which ARAP substantially reduced the number of hard real-time deadline misses.
Minimizing energy under performance constraints on embedded platforms
Authors: Imes Connor , Hoffmann Henry
Published: January 2015

This paper explores the problem of energy optimization in embedded platforms. Specifically, it studies resource allocation strategies for meeting performance constraints with minimal energy consumption. We present a comparison of solutions for both homogeneous and single-ISA heterogeneous multi-core embedded systems. We demonstrate that different hardware platforms have fundamentally different performance/energy tradeoff spaces. As a result, minimizing energy on these platforms requires substantially different resource allocation strategies. Our investigations reveal that one class of systems requires a race-to-idle heuristic to achieve optimal energy consumption, while another requires a never-idle heuristic to achieve the same. The differences are dramatic: choosing the wrong strategy can increase energy consumption by over 2× compared to optimal.
Computational aspects of random serial dictatorship
Authors: Aziz Haris , Brandt Felix , Brill Markus , Mestre Julián
Published: January 2015

Two fundamental problems in economics are voting and assignment. In both settings,
random serial dictatorship
is a well-established mechanism that satisfies anonymity,
ex post
efficiency, and strategyproofness. We present an overview of recent results on the computational complexity of problems related to random serial dictatorship.
High-fat diet-induced β-cell proliferation occurs prior to insulin resistance in C57Bl/6J male mice
Authors: Mosser Rockann E. , Maulis Matthew F. , Moullé Valentine S. , Dunn Jennifer C. , Carboneau Bethany A. , Arasi Kavin , Pappan Kirk , Poitout Vincent , Gannon Maureen
Published: January 2015

Both short- (1 wk) and long-term (2–12 mo) high-fat diet (HFD) studies reveal enhanced β-cell mass due to increased β-cell proliferation. β-Cell proliferation following HFD has been postulated to occur in response to insulin resistance; however, whether HFD can induce β-cell proliferation independent of insulin resistance has been controversial. To examine the kinetics of HFD-induced β-cell proliferation and its correlation with insulin resistance, we placed 8-wk-old male C57Bl/6J mice on HFD for different lengths of time and assayed the following: glucose tolerance, insulin secretion in response to glucose, insulin tolerance, β-cell mass, and β-cell proliferation. We found that β-cell proliferation was significantly increased after only 3 days of HFD feeding, weeks before an increase in β-cell mass or peripheral insulin resistance was detected. These results were confirmed by hyperinsulinemic euglycemic clamps and measurements of α-hydroxybutyrate, a plasma biomarker of insulin resistance in humans. An increase in expression of key islet-proliferative genes was found in isolated islets from 1-wk HFD-fed mice compared with chow diet (CD)-fed mice. These data indicate that short-term HFD feeding enhances β-cell proliferation before insulin resistance becomes apparent.