bluuebunny/crossref_metadata_2025 huggingface dataset:
TH‐EF‐207A‐04: A Dynamic Contrast Enhanced Cone Beam CT Technique for Evaluation of Renal Functions
Authors: Wang Z , Shi J , Yang Y
Published: July 2016

Purpose:

To develop a simple but robust method for the early detection and evaluation of renal functions using dynamic contrast enhanced cone beam CT technique.

Methods:

Experiments were performed on an integrated imaging and radiation research platform developed by our lab. Animals (n=3) were anesthetized with 20uL Ketamine/Xylazine cocktail, and then received 200uL injection of iodinated contrast agent Iopamidol via tail vein. Cone beam CT was acquired following contrast injection once per minute and up to 25 minutes. The cone beam CT was reconstructed with a dimension of 300×300×800 voxels of 130×130×130um voxel resolution. The middle kidney slices in the transvers and coronal planes were selected for image analysis. A double exponential function was used to fit the contrast enhanced signal intensity versus the time after contrast injection. Both pixel‐based and region of interest (ROI)‐based curve fitting were performed. Four parameters obtained from the curve fitting, namely the amplitude and flow constant for both contrast wash in and wash out phases, were investigated for further analysis.

Results:

Robust curve fitting was demonstrated for both pixel based (with R2>0.8 for >85% pixels within the kidney contour) and ROI based (R2>0.9 for all regions) analysis. Three different functional regions: renal pelvis, medulla and cortex, were clearly differentiated in the functional parameter map in the pixel based analysis. ROI based analysis showed the half‐life T1/2 for contrast wash in and wash out phases were 0.98±0.15 and 17.04±7.16, 0.63±0.07 and 17.88±4.51, and 1.48±0.40 and 10.79±3.88 minutes for the renal pelvis, medulla and cortex, respectively.

Conclusion:

A robust method based on dynamic contrast enhanced cone beam CT and double exponential curve fitting has been developed to analyze the renal functions for different functional regions. Future study will be performed to investigate the sensitivity of this technique in the detection of radiation induced kidney dysfunction.
TH‐E‐209‐02: Dose Monitoring and Protocol Optimization: The Pediatric Perspective
Authors: MacDougall R.
Published: July 2016

Radiation dose monitoring solutions have opened up new opportunities for medical physicists to be more involved in modern clinical radiology practices. In particular, with the help of comprehensive radiation dose data, data‐driven protocol management and informed case follow up are now feasible.

Significant challenges remain however and the problems faced by medical physicists are highly heterogeneous. Imaging systems from multiple vendors and a wide range of vintages co‐exist in the same department and employ data communication protocols that are not fully standardized or implemented making harmonization complex.

Many different solutions for radiation dose monitoring have been implemented by imaging facilities over the past few years. Such systems are based on commercial software, home‐grown IT solutions, manual PACS data dumping, etc., and diverse pathways can be used to bring the data to impact clinical practice. The speakers will share their experiences with creating or tailoring radiation dose monitoring/management systems and procedures over the past few years, which vary significantly in design and scope.

Topics to cover: (1) fluoroscopic dose monitoring and high radiation event handling from a large academic hospital; (2) dose monitoring and protocol optimization in pediatric radiology; and (3) development of a home‐grown IT solution and dose data analysis framework.

Learning Objectives:

Describe the scope and range of radiation dose monitoring and protocol management in a modern radiology practice

Review examples of data available from a variety of systems and how it managed and conveyed.

Reflect on the role of the physicist in radiation dose awareness.
Distinct neural systems recruited when speech production is modulated by different masking sounds
Authors: Meekings Sophie , Evans Samuel , Lavan Nadine , Boebinger Dana , Krieger-Redwood Katya , Cooke Martin , Scott Sophie K.
Published: July 2016

When talkers speak in masking sounds, their speech undergoes a variety of acoustic and phonetic changes. These changes are known collectively as the Lombard effect. Most behavioural research and neuroimaging research in this area has concentrated on the effect of energetic maskers such as white noise on Lombard speech. Previous fMRI studies have argued that neural responses to speaking in noise are driven by the quality of auditory feedback—that is, the audibility of the speaker's voice over the masker. However, we also frequently produce speech in the presence of informational maskers such as another talker. Here, speakers read sentences over a range of maskers varying in their informational and energetic content: speech, rotated speech, speech modulated noise, and white noise. Subjects also spoke in quiet and listened to the maskers without speaking. When subjects spoke in masking sounds, their vocal intensity increased in line with the energetic content of the masker. However, the opposite pattern was found neurally. In the superior temporal gyrus, activation was most strongly associated with increases in informational, rather than energetic, masking. This suggests that the neural activations associated with speaking in noise are more complex than a simple feedback response.
Trigeminocardiac reflex caused by selective angiography of the middle meningeal artery
Authors: Tamura Takamitsu , Rex David E , Marosfoi Miklos G , Puri Ajit S , Gounis Matthew J , Wakhloo Ajay K
Published: July 2016

We describe an interesting case of trigeminocardiac reflex (TCR) caused by selective angiography of the middle meningeal artery (MMA). A 28-year-old woman presented with a symptomatic meningioma. Preoperative tumour embolisation was performed. In the procedure, when selective MMA angiography was done with Omnipaque 300 mg I/mL for 3 mL by manual injection, the patient complained of flashing lights in her eye followed by vomiting and bradycardia down to 40 bpm without increased intracranial pressure signs. On selective MMA angiography, the choroidal crescent and arteries of the periorbital region were opacified by anastomosis from the MMA via the meningo-ophthalmic artery. We diagnosed that her symptoms were caused by selective MMA angiography leading to high pressure stimulation towards the ophthalmic nerve innervation around the orbit as a TCR. We suggest that the operator should be prepared to manage TCR during treatment with expected selective MMA angiography, and gentle low pressure contrast injection should be attempted.
Burning mouth syndrome associated with varicella zoster virus
Authors: Nagel Maria A , Gilden Don
Published: July 2016

We present two cases of burning mouth syndrome (BMS)—of 8-month duration in a 61-year-old woman and of 2-year duration in a 63-year-old woman—both associated with increased levels of antivaricella zoster virus (VZV) IgM antibodies in serum and with pain that improved with antiviral treatment. Combined with our previous finding of BMS due to herpes simplex virus type 1 (HSV-1) infection, we recommend evaluation of patients with BMS not only for VZV or HSV-1 DNA in the saliva, but also for serum anti-VZV and anti-HSV-1 IgM antibodies. Both infections are treatable with oral antiviral agents.
Improving the detection of environmental enteric dysfunction: a lactulose, rhamnose assay of intestinal permeability in children aged under 5 years exposed to poor sanitation and hygiene
Authors: Faubion W A , Camilleri M , Murray J A , Kelly P , Amadi B , Kosek M N , Enders F , Larson J , Grover Madhusudan , Boe G , Dyer R , Singh R
Published: July 2016

Background

Environmental enteric dysfunction (EED) is an asymptomatic intestinal disorder affecting populations living in conditions of poor sanitation and hygiene. The study tested intestinal barrier function in infants with EED.

Methods

We prospectively studied an advanced high-performance liquid chromatography mass spectrometry assay of urine collected after oral intake of the monosaccharide, L-rhamnose and the disaccharide, lactulose, in 112 children from three continents.

Findings

Compared to the US cohort (n=27), the cohorts of children from Peru (n=19) and Zambia (n=85) were older with evidence of growth impairment. The median (range) of age (months) was 8.0 (2.0 to 13.0), 27.0 (15.0 to 29.0) and 21.0 (12.0 to 36.0), respectively. The median (range) of height for age Z score was −0.1 (−1.8 to 2.4), −1.8 (−3.3 to −0.2) and −2.3 (−8.5 to 1.2), respectively. Among children with valid sugar data (n=22 USA, n=19 Peru, n=73 Zambia), there were no significant differences in the median rhamnose urine concentrations between the three groups. The median (range) lactulose concentration (µg/mL) was 6.78 (0.29 to 31.90), 47.60 (4.23 to 379.00) and 75.40 (0.67 to 873.00) in the US, Peruvian and Zambian cohorts, respectively (p<0.001). The lactulose/rhamnose ratio (LRR) was higher in cohorts from Peru (0.75, 0.15, 5.02) and Zambia (2.26, 0.08, 14.48) compared to the US (0.14, 0.06, 1.00) cohort (p<0.001). In a multivariate effect modification model, higher weight-for-age z scores were associated with lower post-dose lactulose when rhamnose excretion was constant (p=0.003).

Conclusions

This non-invasive two saccharide permeability protocol measures changes in intestinal permeability in children with EED and permits the identification of individuals for interventional trials.
Managed Activity Graded Exercise iN Teenagers and pre-Adolescents (MAGENTA) feasibility randomised controlled trial: study protocol
Authors: Brigden Amberly , Beasant Lucy , Hollingworth William , Metcalfe Chris , Gaunt Daisy , Mills Nicola , Jago Russell , Crawley Esther
Published: July 2016

Introduction

Paediatric chronic fatigue syndrome or myalgic encephalomyelitis (CFS/ME) is a relatively common and disabling condition, yet there is a limited evidence base for treatment. There is good evidence that graded exercise therapy is moderately effective in adults with CFS/ME, but there is little evidence for the effectiveness, cost-effectiveness, acceptability or best method of delivery for paediatric CFS/ME. This study aims to investigate the acceptability and feasibility of carrying out a multicentre randomised controlled trial investigating the effectiveness of graded exercise therapy compared with activity management for children/teenagers who are mildly or moderately affected with CFS/ME.

Methods and analysis

100 paediatric patients (8–17 years) with CFS/ME will be recruited from 3 specialist UK National Health Service (NHS) CFS/ME services (Bath, Cambridge and Newcastle). Patients will be randomised (1:1) to receive either graded exercise therapy or activity management. Feasibility analysis will include the number of young people eligible, approached and consented to the trial; attrition rate and treatment adherence; questionnaire and accelerometer completion rates. Integrated qualitative methods will ascertain perceptions of feasibility and acceptability of recruitment, randomisation and the interventions. All adverse events will be monitored to assess the safety of the trial.

Ethics and dissemination

The trial has received ethical approval from the National Research Ethics Service (South West—Frenchay 15/SW/0124).

Trial registration number

ISRCTN23962803; Pre-results.
Sleeve gastrectomy versus Roux-en-Y gastric bypass for type 2 diabetes and morbid obesity: double-blind randomised clinical trial protocol
Authors: Murphy Rinki , Evennett Nicholas J , Clarke Michael G , Robinson Steven J , Humphreys Lee , Jones Bronwen , Kim David D , Cutfield Richard , Plank Lindsay D , Hammodat Hisham , Booth Michael W C
Published: July 2016

Introduction

Type 2 diabetes (T2D) in association with obesity is an increasing disease burden. Bariatric surgery is the only effective therapy for achieving remission of T2D among those with morbid obesity. It is unclear which of the two most commonly performed types of bariatric surgery, laparoscopic sleeve gastrectomy (LSG) and laparoscopic Roux-en-Y gastric bypass (LRYGB), is most effective for obese patients with T2D. The primary objective of this study is to determine whether LSG or LRYGB is more effective in achieving HbA1c<6% (<42 mmol/mol) without the use of diabetes medication at 5 years.

Methods and analysis

Single-centre, double-blind (assessor and patient), parallel, randomised clinical trial (RCT) conducted in New Zealand, targeting 106 patients. Eligibility criteria include age 20–55 years, T2D of at least 6 months duration and body mass index 35–65 kg/m2for at least 5 years. Randomisation 1:1 to LSG or LRYGB, used random number codes disclosed to the operating surgeon after induction of anaesthesia. A standard medication adjustment schedule will be used during postoperative metabolic assessments. Secondary outcomes include proportions achieving HbA1c<5.7% (39 mmol/mol) or HbA1c<6.5% (48 mmol/mol) without the use of diabetes medication, comparative weight loss, obesity-related comorbidity, operative complications, revision rate, mortality, quality of life, anxiety and depression scores. Exploratory outcomes include changes in satiety, gut hormone and gut microbiota to gain underlying mechanistic insights into T2D remission.

Ethics and dissemination

Ethics approval was obtained from the New Zealand regional ethics committee (NZ93405) who also provided independent safety monitoring of the trial. Study commenced in September 2011. Recruitment completed in October 2014. Data collection is ongoing. Results will be reported in manuscripts submitted to peer-reviewed journals and in presentations at national and international meetings.

Trial registration numbers

ACTRN12611000751976,NCT01486680; Pre-results.
A snapshot survey of perceptions of healthcare professionals on ageing surgeons
Authors: Rajaratnam Vaikunthan , Kumar Chandra M , Roy Chowdhury Anupama , Su Chang
Published: July 2016

Objective

The aim of this research was to understand healthcare professionals’ perception of the continued practice of ageing surgeons in Singapore.

Methodology

A quantitative method was chosen for this research to determine healthcare professionals’ perception of the practice of ageing surgeons. Ethical approval was obtained from the local ethical review board. A cross-sectional method using a population survey was performed among healthcare professionals in two tertiary institutions and the study was confined to stakeholders in practices of ageing surgeons. The population sampled was limited to nurses in the theatre, anaesthetists, surgeons and geriatricians (physicians). An online questionnaire was designed for the survey that took into consideration the various conceptual frameworks of ageing surgeons’ practice that was obtained from a literature review.

Results

There were 104 respondents of a population of 350 sampled (theatre nurses, anaesthetists, physicians and surgeons) giving a respondent rate of 30%. The mean age of the participants was 39.7; 72% were doctors (surgeons 34%, physicians 20% and anaesthetists 18%) and 28% nurses. Only 35% agreed with the statement that older surgeons face deterioration in cognitive faculties and 29% remained neutral. A similar trend was seen with the perception that older surgeons face a decline in memory. However, 44% agreed with the statement that older surgeons face a decline in visuospatial ability and another 40% agreed that they had a decline in psychomotor skills and reaction time. Fifty per cent agreed with the statement that they face deterioration in physical abilities. Sixty-three per cent did not think that older surgeons face a decline in reasoning and judgement. Forty-eight per cent believed that older surgeons’ vast fund of knowledge and experience could compensate for physical and cognitive changes. Only 13% agreed with the statement that older surgeons have higher surgical mortality. Forty-five per cent agreed that the retirement age should be 65 while 22% believed it should be over 65. Forty-four per cent agreed that a regular multidisciplinary, objective and comprehensive evaluation of an older surgeon’s physical and cognitive function would help to identify and treat reversible problems which when corrected would aid in restoring the surgeon’s function. Seventy-four per cent felt that it was the responsibility of all stakeholders to decide or report on when an ageing surgeon is unsafe to continue practicing. Fifty-five per cent disagreed with a mandatory retirement age for surgeons.

Conclusions

This study showed that, in Singapore, stakeholders agreed there are changes in physical and cognitive abilities of ageing surgeons but they thought that these can be overcome with selective strategies to optimise their role in the workforce. They also disagreed on a mandatory retirement age.
Average symptom trajectories following incident radiographic knee osteoarthritis: data from the Osteoarthritis Initiative
Authors: Whittle Rebecca , Jordan Kelvin P , Thomas Elaine , Peat George
Published: July 2016

Introduction

Previous research has identified the existence of a prodromal phase of symptom worsening beginning on average 2–3 years prior to the first appearance of radiographic knee osteoarthritis (OA). The current study extends these observations to investigate the trajectory of self-reported pain, stiffness, function and other symptoms following the incidence of radiographic OA.

Methods

Data were from the incidence cohort of the Osteoarthritis Initiative public use data sets. Cases were defined as knees without symptoms at enrolment, which developed incident radiographic OA (Kellgren and Lawrence grade ≥2) at any of the first 4 annual follow-up visits. Symptoms investigated were knee-specific Western Ontario & McMaster Universities Osteoarthritis Index and Knee injury and Osteoarthritis Outcome Score subscale scores and individual items, available up to 3 years before and 5 years after the incidence of radiographic OA. Trajectories of having at least one of the symptoms from a subscale, and for each individual symptom over time, were fitted using multilevel logistic regression models.

Results

The probability of symptoms following the initial prodromal phase generally stabilised, whereas the probability of moderate, severe or extreme symptoms was consistently low. Two exceptions were pain frequency, which increased greatly in the lead up to incidence, then decreased slightly, and audible joint sounds, which had a much higher overall probability, and after increasing prior to incident radiographic OA, stabilised then started to increase again at 5 years.

Conclusions

Following an increase in the risk of symptoms during the prodromal phase, this risk does not continue to increase in the period up to 5 years after the incidence of radiographic OA.
A winter dysentery (coronavirus infection) outbreak in a dairy herd in Galicia (northwestern Spain)
Authors: Abuelo Angel , Perez‐Santos Maria
Published: July 2016

Bovine coronavirus infections in adult cattle are commonly referred as to winter dysentery and present as an epidemic outbreak characterised by the sudden onset of diarrhoea with fresh blood that presents with high morbidity but low mortality. Despite the low mortality, milk production may not return fully to expected levels until several weeks post infection. This case report demonstrates the symptoms, examination and evaluation of a referred outbreak of winter dysentery in adult and youngstock cattle in a dairy herd located in northwestern Spain, highlighting the importance of precise questioning and on‐farm assessment for examining the biocontainment practices of a herd.
Do prior diel thermal cycles influence the physiological response of Atlantic salmon (Salmo salar) to subsequent heat stress?
Authors: Tunnah Louise , Currie Suzanne , MacCormack Tyson J.
Published: July 2016

We designed two environmentally relevant thermal cycling regimes using monitoring data from an Atlantic salmon (Salmo salar) river to determine whether exposure to prior diel cycles stimulated protective mechanisms (e.g., heat hardening) and (or) resulted in physiological and cellular stress. Wild fish were exposed to 3 days of diel cycling in the lab and then exposed to an acute thermal challenge near their upper reported critical temperature. We measured routine metabolic rate across the time course as well as indicators of physiological status (e.g., plasma glucose and osmolality) and cellular stress (e.g., heat shock protein 70). We observed that thermal cycling altered physiological and cellular responses, compared with an acute heat shock, but saw no differences between cycling regimes. Unique temperature regime and tissue-specific responses were observed in heat shock protein induction, metabolites, haematology, and osmotic indicators. Routine metabolic rate was not affected by the thermal cycling and increased according to Q10predictions. While we report unique physiological and cellular responses among all treatment groups, we did not observe a clear indication of a heat hardening response.
Biochar influences on agricultural soils, crop production, and the environment: A review
Authors: Ahmed Ahmed , Kurian Jiby , Raghavan Vijaya
Published: July 2016

Given its high pore volume and adsorption capacity, and when applied as an agricultural soil amendment, its ability to enhance the soil’s nutrient- and water- holding capacities, biochar has become a focus of research interest. In most applications, crop productivity is significantly increased after agricultural soils are amended with biochar. In addition to increasing soil quality, the biochar amendments sequester carbon within the soil. However, the long-term effects of amending agricultural soils with biochar are difficult to predict, because the mechanisms behind the increase in productivity of biochar amended soils are not yet fully understood. Long-term detrimental effects on soil and the environment can occur if biochar is applied haphazardly. Current knowledge and the additional experimental work required to thoroughly understand the influence of biochar amendment on the behavior of agricultural soils processes are reviewed. Further, studies on the post production processing of biochar are discussed in the context of the possible engineering of biochar for particular states of soil degradation.
Holographic superconductors in IR modified Hořava–Lifshitz gravity
Authors: Lu Jun-Wang , Wu Ya-Bo , Xiao Jian , Lu Cui-Juan , Liu Mo-Lin
Published: July 2016

In the probe limit, we study the holographic [Formula: see text]- and [Formula: see text]-wave superconductors in the IR modified Hořava–Lifshitz gravity and obtain the effect of the gravity parameter [Formula: see text] on the condensate and the AC conductivity. Concretely, for the two models, the increasing [Formula: see text] makes the superconductor phase transition more difficult. Moreover, at the critical point, both systems undergo a second-order phase transition as expected from the mean field theory, and the superfluid density decreases with the temperature linearly, which is consistent with the Ginzburg–Landau theory. Meanwhile, the analytical results back up the numerical results. What is more, in the superconducting phase, the ratio of the energy gap to the critical temperature, i.e. [Formula: see text], decreases with the increasing [Formula: see text]. In addition, our results generalize the previous work on holographic superconductors in Hořava–Lifshitz gravity to some extent.
Global existence of solutions for a multi-phase flow: A drop in a gas-tube
Authors: Amadori Debora , Baiti Paolo , Corli Andrea , Santo Edda Dal
Published: July 2016

In this paper we study the flow of an inviscid fluid composed by three different phases. The model is a simple hyperbolic system of three conservation laws, in Lagrangian coordinates, where the phase interfaces are stationary. Our main result concerns the global existence of weak entropic solutions to the initial-value problem for large initial data.
Distributed Intelligent MEMS
Authors: Liang Junbin , Cao Jiannong , Liu Rui , Li Tao
Published: July 2016

In recent years, distributed intelligent microelectromechanical systems (DiMEMSs) have appeared as a new form of distributed embedded systems. DiMEMSs contain thousands or millions of removable autonomous devices, which will collaborate with each other to achieve the final target of the whole system. Programming such systems is becoming an extremely difficult problem. The difficulty is due not only to their inherent nature of distributed collaboration, mobility, large scale, and limited resources of their devices (e.g., in terms of energy, memory, communication, and computation) but also to the requirements of real-time control and tolerance for uncertainties such as inaccurate actuation and unreliable communications. As a result, existing programming languages for traditional distributed and embedded systems are not suitable for DiMEMSs. In this article, we first introduce the origin and characteristics of DiMEMSs and then survey typical implementations of DiMEMSs and related research hotspots. Finally, we propose a real-time programming framework that can be used to design new real-time programming languages for DiMEMSs. The framework is composed of three layers: a real-time programming model layer, a compilation layer, and a runtime system layer. The design challenges and requirements of these layers are investigated. The framework is then discussed in further detail and suggestions for future research are given.
Consistency in Non-Transactional Distributed Storage Systems
Authors: Viotti Paolo , Vukolić Marko
Published: July 2016

Over the years, different meanings have been associated with the word
consistency
in the distributed systems community. While in the ’80s “consistency” typically meant
strong consistency
, later defined also as
linearizability
, in recent years, with the advent of highly available and scalable systems, the notion of “consistency” has been at the same time both weakened and blurred.

In this article, we aim to fill the void in the literature by providing a structured and comprehensive overview of different consistency notions that appeared in distributed systems, and in particular
storage
systems research, in the last four decades. We overview more than 50 different consistency notions, ranging from linearizability to eventual and weak consistency, defining precisely many of these, in particular where the previous definitions were ambiguous. We further provide a partial order among different consistency predicates, ordering them by their semantic “strength,” which we believe will be useful in future research. Finally, we map the consistency semantics to different practical systems and research prototypes.

The scope of this article is restricted to non-transactional semantics, that is, those that apply to single storage object operations. As such, our article complements the existing surveys done in the context of transactional, database consistency semantics.
Using Cohesion and Coupling for Software Remodularization
Authors: Candela Ivan , Bavota Gabriele , Russo Barbara , Oliveto Rocco
Published: July 2016

Refactoring and, in particular, remodularization operations can be performed to repair the design of a software system and remove the erosion caused by software evolution. Various approaches have been proposed to support developers during the remodularization of a software system. Most of these approaches are based on the underlying assumption that developers pursue an optimal balance between cohesion and coupling when modularizing the classes of their systems. Thus, a remodularization recommender proposes a solution that implicitly provides a (near) optimal balance between such quality attributes. However, there is still no empirical evidence that such a balance is the
desideratum
by developers. This article aims at analyzing both objectively and subjectively the aforementioned phenomenon. Specifically, we present the results of (1) a large study analyzing the modularization quality, in terms of package cohesion and coupling, of 100 open-source systems, and (2) a survey conducted with 29 developers aimed at understanding the driving factors they consider when performing modularization tasks. The results achieved have been used to distill a set of lessons learned that might be considered to design more effective remodularization recommenders.
A Distributed-Memory Package for Dense Hierarchically Semi-Separable Matrix Computations Using Randomization
Authors: Rouet François-Henry , Li Xiaoye S. , Ghysels Pieter , Napov Artem
Published: July 2016

We present a distributed-memory library for computations with dense structured matrices. A matrix is considered structured if its off-diagonal blocks can be approximated by a rank-deficient matrix with low numerical rank. Here, we use Hierarchically Semi-Separable (HSS) representations. Such matrices appear in many applications, for example, finite-element methods, boundary element methods, and so on. Exploiting this structure allows for fast solution of linear systems and/or fast computation of matrix-vector products, which are the two main building blocks of matrix computations. The
compression
algorithm that we use, that computes the HSS form of an input dense matrix, relies on randomized sampling with a novel adaptive sampling mechanism. We discuss the parallelization of this algorithm and also present the parallelization of structured matrix-vector product, structured factorization, and solution routines. The efficiency of the approach is demonstrated on large problems from different academic and industrial applications, on up to 8,000 cores.

This work is part of a more global effort, the STRUctured Matrices PACKage (STRUMPACK) software package for computations with sparse and dense structured matrices. Hence, although useful on their own right, the routines also represent a step in the direction of a distributed-memory sparse solver.
Hexahedral-Dominant Meshing
Authors: Sokolov Dmitry , Ray Nicolas , Untereiner Lionel , Lévy Bruno
Published: July 2016

This article introduces a method that generates a hexahedral-dominant mesh from an input tetrahedral mesh. It follows a three-step pipeline similar to the one proposed by Carrier Baudoin et al.: (1) generate a frame field, (2) generate a pointset
P
that is mostly organized on a regular grid locally aligned with the frame field, and (3) generate the hexahedral-dominant mesh by recombining the tetrahedra obtained from the constrained Delaunay triangulation of
P
.

For step (1), we use a state-of-the-art algorithm to generate a smooth frame field. For step (2), we introduce an extension of Periodic Global Parameterization to the volumetric case. As compared with other global parameterization methods (such as CubeCover), our method relaxes some global constraints to avoid creating degenerate elements, at the expense of introducing some singularities that are meshed using non-hexahedral elements. For step (3), we build on the formalism introduced by Meshkat and Talmor, fill in a gap in their proof, and provide a complete enumeration of all the possible recombinations, as well as an algorithm that efficiently detects all the matches in a tetrahedral mesh.

The method is evaluated and compared with the state of the art on a database of examples with various mesh complexities, varying from academic examples to real industrial cases. Compared with the method of Carrier-Baudoin et al., the method results in better scores for classical quality criteria of hexahedral-dominant meshes (hexahedral proportion, scaled Jacobian, etc.). The method also shows better robustness than CubeCover and its derivatives when applied to complicated industrial models.
Affordances
Authors: Burlamaqui Leonardo , Dong Andy
Published: July 2016

This forum addresses conceptual, methodological, and professional issues that arise in the UX field's continuing effort to contribute robust information about users to product planning and design.
--- David Siegel and Susan Dray, Editors
Like It or Not
Authors: Giachanou Anastasia , Crestani Fabio
Published: July 2016

Sentiment analysis in Twitter is a field that has recently attracted research interest. Twitter is one of the most popular microblog platforms on which users can publish their thoughts and opinions. Sentiment analysis in Twitter tackles the problem of analyzing the tweets in terms of the opinion they express. This survey provides an overview of the topic by investigating and briefly describing the algorithms that have been proposed for sentiment analysis in Twitter. The presented studies are categorized according to the approach they follow. In addition, we discuss fields related to sentiment analysis in Twitter including Twitter opinion retrieval, tracking sentiments over time, irony detection, emotion detection, and tweet sentiment quantification, tasks that have recently attracted increasing attention. Resources that have been used in the Twitter sentiment analysis literature are also briefly presented. The main contributions of this survey include the presentation of the proposed approaches for sentiment analysis in Twitter, their categorization according to the technique they use, and the discussion of recent research trends of the topic and its related fields.
Confidentiality-Preserving Publish/Subscribe
Authors: Onica Emanuel , Felber Pascal , Mercier Hugues , Rivière Etienne
Published: July 2016

Publish/subscribe (pub/sub) is an attractive communication paradigm for large-scale distributed applications running across multiple administrative domains. Pub/sub allows event-based information dissemination based on constraints on the nature of the data rather than on pre-established communication channels. It is a natural fit for deployment in untrusted environments such as public clouds linking applications across multiple sites. However, pub/sub in untrusted environments leads to major confidentiality concerns stemming from the content-centric nature of the communications. This survey classifies and analyzes different approaches to confidentiality preservation for pub/sub, from applications of trust and access control models to novel encryption techniques. It provides an overview of the current challenges posed by confidentiality concerns and points to future research directions in this promising field.
Extensions from the 'field'
Authors: Fox Sarah , Rosner Daniela
Published: July 2016

Community + Culture features practitioner perspectives on designing technologies for and with communities. We highlight compelling projects and provocative points of view that speak to both community technology practice and the interaction design field as a whole.
--- Christopher A. Le Dantec, Editor
Asymptotics of Insensitive Load Balancing and Blocking Phases
Authors: Jonckheere Matthieu , Prabhu Balakrishna J.
Published: July 2016

Load balancing with various types of load information has become a key component of modern communication and information systems. In many systems, characterizing precisely the blocking probability allows to establish a performance trade-off between delay and losses. We address here the problem of giving robust performance bounds based on the study of the asymptotic behavior of the insensitive load balancing schemes when the number of servers and the load scales jointly. These schemes have the desirable property that the stationary distribution of the resulting stochastic network depends on the distribution of job sizes only through its mean. It was shown that they give good estimates of performance indicators for systems with finite buffers, generalizing henceforth Erlang's formula whereas optimal policies are already theoretically and computationally out of reach for networks of moderate size.

We study a single class of traffic acting on a symmetric set of processor sharing queues with finite buffers and we consider the case where the load scales with the number of servers.We characterize the response of symmetric systems under those schemes at different scales and show that three amplitudes of deviations can be identified according to whether ρ < 1, ρ = 1, and ρ > 1. A central limit scaling takes place for a sub-critical load;for ρ=1, the number of free servers scales like n
{θ/θ+1}
(θ being the buffer depth and
n
being the number of servers) and is of order 1 for super-critical loads. This further implies the existence of different phases for the blocking probability. Before a (refined) critical load ρ
c
(n)=1-a n
- {θ/θ+1}
, the blocking is exponentially small and becomes of order n
- {θ/θ+1}
at ρ
c
(n). This generalizes the well-known Quality and Efficiency Driven (QED) regime or Halfin-Whitt regime for a one-dimensional queue, and leads to a generalized staffing rule for a given target blocking probability.
Instability in Distributed Mobility Management
Authors: Li Yuanjie , Deng Haotian , Li Jiayao , Peng Chunyi , Lu Songwu
Published: July 2016

Mobility support is critical to offering seamless data service to mobile devices in 3G/4G cellular networks. To accommodate policy requests by users and carriers, micro-mobility management scheme among cells (i.e., handoff) is designated to be configurable. Each cell and mobile device can configure or even customize its own handoff procedure. In this paper, we examine the handoff misconfiguration issues in 3G/4G networks. We show that they may incur handoff instability in the form of persistent loops, where the device oscillates between cells even without radio-link and location changes. Such instability is mainly triggered by uncoordinated parameter configurations and inconsistent decision logic in the hand- off procedure. It can degrade user data performance, incur excessive signaling overhead, and violate network's expected handoff goals. We derive the instability conditions, and validate them on two major US mobile carrier networks. We further design a soft- ware tool for automatic loop detection, and run it over operational networks. We discuss possible fixes to such uncoordinated configurations among devices and cells.
The Value of Privacy
Authors: Wang Weina , Ying Lei , Zhang Junshan
Published: July 2016

We study the value of data privacy in a game-theoretic model of trading private data, where a data collector purchases private data from strategic data subjects (individuals) through an incentive mechanism. The private data of each individual represents her knowledge about an underlying state, which is the information that the data collector desires to learn. Different from most of the existing work on privacy-aware surveys, our model does not assume the data collector to be trustworthy. Then, an individual takes full control of its own data privacy and reports only a privacy-preserving version of her data. In this paper, the value of ε units of privacy is measured by the minimum payment of all nonnegative payment mechanisms, under which an individual's best response at a Nash equilibrium is to report the data with a privacy level of ε. The higher ε is, the less private the reported data is. We derive lower and upper bounds on the value of privacy which are asymptotically tight as the number of data subjects becomes large. Specifically, the lower bound assures that it is impossible to use less amount of payment to buy ε units of privacy, and the upper bound is given by an achievable payment mechanism that we designed. Based on these fundamental limits, we further derive lower and upper bounds on the minimum total payment for the data collector to achieve a given learning accuracy target, and show that the total payment of the designed mechanism is at most one individual's payment away from the minimum.
Exploiting Core Criticality for Enhanced GPU Performance
Authors: Jog Adwait , Kayiran Onur , Pattnaik Ashutosh , Kandemir Mahmut T. , Mutlu Onur , Iyer Ravishankar , Das Chita R.
Published: July 2016

Modern memory access schedulers employed in GPUs typically optimize for memory throughput. They implicitly assume that all requests from different cores are equally important. However, we show that during the execution of a subset of CUDA applications, different cores can have different amounts of tolerance to latency. In particular, cores with a larger fraction of warps waiting for data to come back from DRAM are less likely to tolerate the latency of an outstanding memory request. Requests from such cores are more critical than requests from others. Based on this observation, this paper introduces a new memory scheduler, called (C)ritica(L)ity (A)ware (M)emory (S)cheduler (CLAMS), which takes into account the latency-tolerance of the cores that generate memory requests. The key idea is to use the fraction of critical requests in the memory request buffer to switch between scheduling policies optimized for criticality and locality. If this fraction is below a threshold, CLAMS prioritizes critical requests to ensure cores that cannot tolerate latency are serviced faster. Otherwise, CLAMS optimizes for locality, anticipating that there are too many critical requests and prioritizing one over another would not significantly benefit performance.

We first present a core-criticality estimation mechanism for determining critical cores and requests, and then discuss issues related to finding a balance between criticality and locality in the memory scheduler. We progressively devise three variants of CLAMS, and show that the Dynamic CLAMS provides significantly higher performance, across a variety of workloads, than the commonly-employed GPU memory schedulers optimized solely for locality. The results indicate that a GPU memory system that considers both core criticality and DRAM access locality can provide significant improvement in performance.
Rumor Source Obfuscation on Irregular Trees
Authors: Fanti Giulia , Kairouz Peter , Oh Sewoong , Ramchandran Kannan , Viswanath Pramod
Published: July 2016

Anonymous messaging applications have recently gained popularity as a means for sharing opinions without fear of judgment or repercussion. Messages in these applications propagate anonymously (without authorship metadata) over a network that is typically defined by social connections or physical proximity. However, recent advances in rumor source detection show that the source of such an anonymous message can be inferred by statistical inference attacks. Adaptive diffusion was recently proposed as a solution that achieves optimal source obfuscation over regular trees. However, in real social networks, node degrees differ from node to node, and adaptive diffusion can be significantly sub-optimal. This gap increases as the degrees become more irregular.

In order to quantify this gap, we model the underlying network as coming from standard branching processes with i.i.d. degree distributions. Building upon the analysis techniques from branching processes, we give an analytical characterization of the dependence between the probability of detection achieved by adaptive diffusion and the degree distribution. Further, this analysis provides a key insight: passing a rumor to a friend who has many friends makes the source more ambiguous. This leads to a new family of protocols that we call Preferential Attachment Adaptive Diffusion (PAAD). When messages are propagated according to PAAD, we give both the MAP estimator for finding the source and also an analysis of the probability of detection achieved by this adversary. The analytical results are not directly comparable, since the adversary's observed information has a different distribution under adaptive diffusion than under PAAD. Instead, we present results from numerical experiments that suggest that PAAD achieves a lower probability of detection, at the cost of increased communication for coordination.
On the Duration and Intensity of Competitions in Nonlinear Pólya Urn Processes with Fitness
Authors: Jiang Bo , Figueiredo Daniel R. , Ribeiro Bruno , Towsley Don
Published: July 2016

Cumulative advantage (CA) refers to the notion that accumulated resources foster the accumulation of further resources in competitions, a phenomenon that has been empirically observed in various contexts. The oldest and arguably simplest mathematical model that embodies this general principle is the Pólya urn process, which finds applications in a myriad of problems. The original model captures the dynamics of competitions between two equally fit agents under linear CA effects, which can be readily generalized to incorporate different fitnesses and nonlinear CA effects. We study two statistics of competitions under the generalized model, namely duration (i.e., time of the last tie) and intensity (i.e., number of ties). We give rigorous mathematical characterizations of the tail distributions of both duration and intensity under the various regimes for fitness and nonlinearity, which reveal very interesting behaviors. For example, fitness superiority induces much shorter competitions in the sublinear regime while much longer competitions in the superlinear regime. Our findings can shed light on the application of Pólya urn processes in more general contexts where fitness and nonlinearity may be present.
Freestyle Dancing
Authors: Liu Liang , Wang Yating , Fortnow Lance , Li Jin , Xu Jun
Published: July 2016

In this work, we study a challenging research problem that arises in minimizing the cost of storing customer data online for reliable accesses in a cloud. It is how to near-perfectly balance the remaining capacities of all disks across the cloud system while adding new file blocks so that the inevitable event of capacity expansion can be postponed as much as possible. The challenges of solving this problem are twofold. First, new file blocks are added to the cloud concurrently by many dispatchers (computing servers) that have no communication or coordination among themselves. Though each dispatcher is updated with information on disk occupancies, the update is infrequent and not synchronized. Second, for fault-tolerance purposes, a combinatorial constraint has to be satisfied in distributing the blocks of each new file across the cloud system. We propose a randomized algorithm, in which each dispatcher independently samples a blocks-to-disks assignment according to a probability distribution on a set of assignments conforming to the aforementioned combinatorial requirement. We show that this algorithm allows a cloud system to near-perfectly balance the remaining disk capacities as rapidly as theoretically possible, when starting from any unbalanced state that is correctable mathematically.
Explicit Back-off Rates for Achieving Target Throughputs in CSMA/CA Networks
Authors: Van Houdt Benny
Published: July 2016

CSMA/CA networks have often been analyzed using a stylized model that is fully characterized by a vector of back-off rates and a conflict graph. We present an explicit formula for the unique vector of back-off rate needed to achieve any achievable throughput vector provided that the network has a chordal conflict graph. These back-off rates are such that the back-off rate of a node only depends on its own target throughput and the target throughput of its neighbors and can be determined in a distributed manner. We also introduce a distributed chordal approximation algorithm for general conflict graphs which is shown (using numerical examples) to be more accurate than the Bethe approximation.