bluuebunny/crossref_metadata_2025 huggingface dataset:
Disease Progression and Resolution in Rodent Models of Clostridium difficile Infection and Impact of Antitoxin Antibodies and Vancomycin
Authors: Warn Peter , Thommes Pia , Sattar Abdul , Corbett David , Flattery Amy , Zhang Zuo , Black Todd , Hernandez Lorraine D. , Therien Alex G.
Published: August 2016

Clostridium difficile
causes infections of the colon in susceptible patients. Specifically, gut dysbiosis induced by treatment with broad-spectrum antibiotics facilitates germination of ingested
C. difficile
spores, expansion of vegetative cells, and production of symptom-causing toxins TcdA and TcdB. The current standard of care for
C. difficile
infections (CDI) consists of administration of antibiotics such as vancomycin that target the bacterium but also perpetuate gut dysbiosis, often leading to disease recurrence. The monoclonal antitoxin antibodies actoxumab (anti-TcdA) and bezlotoxumab (anti-TcdB) are currently in development for the prevention of recurrent CDI. In this study, the effects of vancomycin or actoxumab/bezlotoxumab treatment on progression and resolution of CDI were assessed in mice and hamsters. Rodent models of CDI are characterized by an early severe phase of symptomatic disease, associated with high rates of morbidity and mortality; high intestinal
C. difficile
burden; and a disrupted intestinal microbiota. This is followed in surviving animals by gradual recovery of the gut microbiota, associated with clearance of
C. difficile
and resolution of disease symptoms over time. Treatment with vancomycin prevents disease initially by inhibiting outgrowth of
C. difficile
but also delays microbiota recovery, leading to disease relapse following discontinuation of therapy. In contrast, actoxumab/bezlotoxumab treatment does not impact the
C. difficile
burden but rather prevents the appearance of toxin-dependent symptoms during the early severe phase of disease, effectively preventing disease until the microbiota (the body's natural defense against
C. difficile
) has fully recovered. These data provide insight into the mechanism of recurrence following vancomycin administration and into the mechanism of recurrence prevention observed clinically with actoxumab/bezlotoxumab.
Correlation of Checkerboard Synergy Testing with Time-Kill Analysis and Clinical Outcomes of Extensively Drug-Resistant Acinetobacter baumannii Respiratory Infections
Authors: Bremmer Derek N. , Bauer Karri A. , Pouch Stephanie M. , Thomas Keelie , Smith Debra , Goff Debra A. , Pancholi Preeti , Balada-Llasat Joan-Miquel
Published: August 2016

We tested 76 extensively drug-resistant (XDR)
Acinetobacter baumannii
isolates by the checkerboard method using only wells containing serum-achievable concentrations (SACs) of drugs. Checkerboard results were correlated by time-kill assay and clinical outcomes. Minocycline-colistin was the best combination
in vitro
, as it inhibited growth in one or more SAC wells in all isolates. Patients who received a combination that inhibited growth in one or more SAC wells demonstrated better microbiological clearance than those who did not (88% versus 30%;
P
= 0.025). The checkerboard platform may have clinical utility for XDR
A. baumannii
infections.
Lipopolysaccharide Domains Modulate Urovirulence
Authors: Aguiniga Lizath M. , Yaggie Ryan E. , Schaeffer Anthony J. , Klumpp David J.
Published: August 2016

Uropathogenic
Escherichia coli
(UPEC) accounts for 80 to 90% of urinary tract infections (UTI), and the increasing rate of antibiotic resistance among UPEC isolates reinforces the need for vaccines to prevent UTIs and recurrent infections. Previous studies have shown that UPEC isolate NU14 suppresses proinflammatory NF-κB-dependent cytokines (D. J. Klumpp, A. C. Weiser, S. Sengupta, S. G. Forrestal, R. A. Batler, and A. J. Schaeffer, Infect Immun 69:6689–6695, 2001,
http://dx.doi.org/10.1128/IAI.69.11.6689-6695.2001
; B. K. Billips, A. J. Schaeffer, and D. J. Klumpp, Infect Immun 76:3891–3900, 2008,
http://dx.doi.org/10.1128/IAI.00069-08
). However, modification of lipopolysaccharide (LPS) structure by deleting the O-antigen ligase gene (
waaL
) enhanced proinflammatory cytokine secretion. Vaccination with the Δ
waaL
mutant diminished NU14 reservoirs and protected against subsequent infections. Therefore, we hypothesized that LPS structural determinants shape immune responses. We evaluated the contribution of LPS domains to urovirulence corresponding to the inner core (
waaP
,
waaY
, and
rfaQ
), outer core (
rfaG
), and O-antigen (
waaL
,
wzzE
, and
wzyE
). Deletion of
waaP
,
waaY
, and
rfaG
attenuated adherence to urothelial cells
in vitro
. In a murine UTI model, the Δ
rfaG
mutant had the most severe defect in colonization. The mutation of
rfaG
,
waaL
,
wzzE
, and
wzyE
resulted in an inability to form reservoirs in mouse bladders. Infection with the LPS mutant panel resulted in various levels of urinary myeloperoxidase. Since the Δ
waaL
mutant promoted Th
1
-associated adaptive responses in previous studies (B. K. Billips, R. E. Yaggie, J. P. Cashy, A. J. Schaeffer, and D. J. Klumpp, J Infect Dis 200:263–272, 2009,
http://dx.doi.org/10.1086/599839
), we assessed NU14 for Th
2
-associated cytokines. We found NU14 infection stimulated TLR4-dependent bladder interleukin-33 (IL-33) production. Inoculation with
rfaG
,
waaL
,
wzzE
, and
wzyE
mutants showed decreased IL-33 production. We quantified antigen-specific antibodies after infection and found significantly increased IgE and IgG1 in Δ
waaP
mutant-infected mice. Our studies show LPS structural constituents mediate multiple aspects of the UPEC life cycle, including the ability to acutely colonize bladders, form reservoirs, and evoke innate and adaptive immune responses.
Inhibition of P2X Receptors Protects Human Monocytes against Damage by Leukotoxin from Aggregatibacter actinomycetemcomitans and α-Hemolysin from Escherichia coli
Authors: Fagerberg Steen K. , Jakobsen Martin R. , Skals Marianne , Praetorius Helle A.
Published: August 2016

α-Hemolysin (HlyA) from
Escherichia coli
and leukotoxin A (LtxA) from
Aggregatibacter actinomycetemcomitans
are important virulence factors in ascending urinary tract infections and aggressive periodontitis, respectively. The extracellular signaling molecule ATP is released immediately after insertion of the toxins into plasma membranes and, via P2X receptors, is essential for the erythrocyte damage inflicted by these toxins. Moreover, ATP signaling is required for the ensuing recognition and phagocytosis of damaged erythrocytes by the monocytic cell line THP-1. Here, we investigate how these toxins affect THP-1 monocyte function. We demonstrate that both toxins trigger early ATP release and a following increase in the intracellular Ca
2+
concentration ([Ca
2+
]
i
) in THP-1 monocytes. The HlyA- and LtxA-induced [Ca
2+
]
i
response is diminished by the P2 receptor antagonist in a pattern that fits the functional P2 receptor expression in these cells. Both toxins are capable of lysing THP-1 cells, with LtxA being more aggressive. Either desensitization or blockage of P2X
1
, P2X
4
, or P2X
7
receptors markedly reduces toxin-induced cytolysis. This pattern is paralleled in freshly isolated human monocytes from healthy volunteers. Interestingly, only a minor fraction of the toxin-damaged THP-1 monocytes eventually lyse. P2X
7
receptor inhibition generally prevents cell damage, except from a distinct cell shrinkage that prevails in response to the toxins. Moreover, we find that preexposure to HlyA preserves the capacity of THP-1 monocytes to phagocytose damaged erythrocytes and may induce readiness to discriminate between damaged and healthy erythrocytes. These findings suggest a new pharmacological target for protecting monocytes during exposure to pore-forming cytolysins during infection or injury.
Pseudomonas aeruginosa Condensins Support Opposite Differentiation States
Authors: Zhao Hang , Clevenger April L. , Ritchey Jerry W. , Zgurskaya Helen I. , Rybenkov Valentin V.
Published: August 2016

Condensins play a key role in global chromosome packing.
Pseudomonas aeruginosa
encodes two condensins, SMC-ScpAB and MksBEF. We report here that the two proteins are involved in the differentiation of the bacterium and impose opposite physiological states. The inactivation of SMC induced a state characterized by increased adhesion to surfaces as well as defects in competitive growth and colony formation. In contrast, MksB-deficient cells were impaired in biofilm formation with no obvious defects during planktonic growth. The phenotype of the double mutant was dominated by the absence of MksB, indicating that the observed growth defects are regulatory in their nature rather than structural. ATPase mutations recapitulated many of the phenotypes of the condensins, indicating their requirement for a functional protein. Additionally, inactivation of condensins dramatically reduced the virulence of the bacterium in a murine model of lung infection. These data demonstrate that condensins are involved in the differentiation of
P. aeruginosa
and reveal their importance for pathogenicity.

IMPORTANCE
Adaptation and differentiation play key roles in bacterial pathogenicity. In
Pseudomonas aeruginosa
, an opportunistic human pathogen, these processes are mediated by the activity of an intricate regulatory network. We describe here novel members of this network, condensins. We show that the two
P. aeruginosa
condensins specialize in the establishment of the sessile and planktonic states of the bacterium. Whereas condensins have well-established roles in global chromosome organization, their roles in regulating bacterial physiology have remained unknown. Our data indicate that the two programs may be linked. We further show that condensins are essential for the pathogenicity of
P. aeruginosa
.
Depletion of Undecaprenyl Pyrophosphate Phosphatases Disrupts Cell Envelope Biogenesis in Bacillus subtilis
Authors: Zhao Heng , Sun Yingjie , Peters Jason M. , Gross Carol A. , Garner Ethan C. , Helmann John D.
Published: August 2016

The integrity of the bacterial cell envelope is essential to sustain life by countering the high turgor pressure of the cell and providing a barrier against chemical insults. In
Bacillus subtilis
, synthesis of both peptidoglycan and wall teichoic acids requires a common C
55
lipid carrier, undecaprenyl-pyrophosphate (UPP), to ferry precursors across the cytoplasmic membrane. The synthesis and recycling of UPP requires a phosphatase to generate the monophosphate form Und-P, which is the substrate for peptidoglycan and wall teichoic acid synthases. Using an optimized
c
lustered
r
egularly
i
nterspaced
s
hort
p
alindromic
r
epeat (CRISPR) system with catalytically inactive (“
d
ead”)
C
RISPR-
as
sociated protein
9
(dCas9)-based transcriptional repression system (CRISPR interference [CRISPRi]), we demonstrate that
B. subtilis
requires either of two UPP phosphatases, UppP or BcrC, for viability. We show that a third predicted lipid phosphatase (YodM), with homology to diacylglycerol pyrophosphatases, can also support growth when overexpressed. Depletion of UPP phosphatase activity leads to morphological defects consistent with a failure of cell envelope synthesis and strongly activates the σ
M
-dependent cell envelope stress response, including
bcrC
, which encodes one of the two UPP phosphatases. These results highlight the utility of an optimized CRISPRi system for the investigation of synthetic lethal gene pairs, clarify the nature of the
B. subtilis
UPP-Pase enzymes, and provide further evidence linking the σ
M
regulon to cell envelope homeostasis pathways.

IMPORTANCE
The emergence of antibiotic resistance among bacterial pathogens is of critical concern and motivates efforts to develop new therapeutics and increase the utility of those already in use. The lipid II cycle is one of the most frequently targeted processes for antibiotics and has been intensively studied. Despite these efforts, some steps have remained poorly defined, partly due to genetic redundancy. CRISPRi provides a powerful tool to investigate the functions of essential genes and sets of genes. Here, we used an optimized CRISPRi system to demonstrate functional redundancy of two UPP phosphatases that are required for the conversion of the initially synthesized UPP lipid carrier to Und-P, the substrate for the synthesis of the initial lipid-linked precursors in peptidoglycan and wall teichoic acid synthesis.
Season and region of birth as risk factors for coeliac disease a key to the aetiology?
Authors: Namatovu Fredinah , Lindkvist Marie , Olsson Cecilia , Ivarsson Anneli , Sandström Olof
Published: August 2016

Background

Coeliac disease (CD) incidence has increased in recent decades, characterised by variations according to sex, age at diagnosis, year of birth, month of birth and region of birth. Genetic susceptibility and exposure to gluten are the necessary factors in CD aetiology, although several environmental factors are considered.

Methods

A nationwide prospective cohort longitudinal study was conducted consisting of 1 912 204 children aged 0–14.9 years born in Sweden from 1991 to 2009. A total of 6569 children were diagnosed with biopsy-verified CD from 47 paediatric departments. Using Cox regression, we examined the association between CD diagnosis and season of birth, region of birth and year of birth.

Results

Overall, CD risk was higher for children born during spring, summer and autumn as compared with children born during winter: adjusted HR for spring 1.08 (95% CI 1.01 to 1.16), summer 1.10 (95% CI 1.03 to 1.18) and autumn 1.10 (95% CI 1.02 to 1.18). Increased CD risk was highest if born in the south, followed by central Sweden when compared with children born in northern Sweden. Children diagnosed at <2 years had an increased CD risk if born in spring while those diagnosed at 2–14.9 years the risk was increased for summer and autumn births. The birth cohort of 1991–1996 had increased CD risk if born during spring, for the 1997–2002 birth cohort the risk increased for summer and autumn births, while for the birth cohort of 2003–2009 the risk was increased if born during autumn.

Conclusions

Season of birth and region of birth are independently and jointly associated with increased risk of developing CD during the first 15 years of life. Seasonal variation in infectious load is the likely explanation.
Left paraduodenal hernia: a rare cause of small bowel obstruction in the elderly
Authors: Barbosa L , Ferreira A , Póvoa A A , Maciel J P
Published: August 2016

Left paraduodenal hernia is a rarely found condition in which the small bowel herniates through a congenital peritoneal defect located behind the 4th portion of duodenum. It usually courses with non-specific symptoms and a widely variable clinical presentation which makes preoperative diagnosis very difficult. It has been associated with a high rate of complications, including bowel strangulation and even death. Prompt surgical intervention consisting of intraoperative surgeon's awareness and recognition of this condition are crucial in order to improve postoperative morbidity and mortality. The authors present a case of a 73-year-old man with acute intestinal obstruction as the first presentation of a left paraduodenal hernia.
Successful use of adalimumab in patient with treatment-refractory microscopic colitis
Authors: Anderson Rebecca Jane , Makins Richard
Published: August 2016

A 50-year-old woman with treatment-refractory lymphocytic colitis was diagnosed with ankylosing spondylitis. She was started on adalimumab injections which significantly improved her stool frequency and consistency and, consequently, her quality of life.
Tibial hypoplasia with a bifid tibia: an unclassified tibial hemimelia
Authors: Shah Krupa , Shah Hitesh
Published: August 2016

Tibial hemimelia is a rare congenital limb deficiency which is characterised by a hypoplastic/aplastic tibia. It actually represents a spectrum of anomalies, ranging from mild hypoplasia of the tibia to total absence of the tibia. Several classifications based on radiological description exist in the literature. The tibial hemimelia is usually described with preaxial mirror polydactyly, split hand/foot syndrome—ectrodactyly, polydactyly—triphalangeal thumb syndrome (Werner syndrome) and micromelia–trigonal brachycephaly syndrome. We describe a child with unclassified tibial hemimelia. The child had right incomplete tibial hemimelia with bifid tibia, left complete tibial hemimelia, bilateral split hands and left split foot. This is the first report of the bifid tibia in the literature.
Upper extremity deep venous thrombosis and pulmonary embolus after ovarian hyperstimulation
Authors: Cramer Anne Catherine Miller , McLean Anna Warszawa , Ahari Jalil
Published: August 2016

A healthy female presented with upper extremity (UE) swelling of several days duration. Admission laboratories were normal except for an elevated D-dimer. An UE ultrasound with Doppler revealed a thrombus in the right subclavian vein. A subsequent chest CT angiogram further characterised the subclavian vein thrombus and also identified a pulmonary embolus. A thorough history and laboratory evaluation showed that her only risk factors were long-time contraceptive pills and a recent cycle of ovarian hyperstimulation (OH) 7 weeks prior to presentation. Anticoagulation treatment was started and the patient's remaining outpatient work-up was negative for all other hereditary causes. A complete anatomic work-up showed bilateral thoracic outlet syndrome (TOS). A review of the literature on the occurrence of upper extremity deep venous thrombosis suggests that these usually occur in the presence of a predisposing factor, including catheters, indwelling devices and active malignancies. OH has been shown to precipitate venous thromboembolism events; however, the diagnosis of bilateral TOS as a predisposing risk factor has not been described in a patient who had recently undergone recent OH and in one who was not actively pregnant.
Barriers to becoming a female surgeon and the influence of female surgical role models
Authors: Kerr Hui-Ling , Armstrong Lesley Ann , Cade Jennifer Ellen
Published: August 2016

Objectives

We aim to investigate the reasons that medical students and junior doctors who are women are less likely to pursue a career in surgery compared with their male counterparts.

Methods

An anonymous questionnaire was distributed to female final year medical students and female junior doctors in two UK hospitals between August and September 2012. Topics included career choice, attitudes to surgery, recognition of female surgical role models and perceived sexual discrimination.

Results

50 medical students and 50 junior doctors were given our survey. We received a 96% response rate; 46 medical students and 50 junior doctors. 6/50 (12%) junior doctors planned a career in surgery compared with 14/46 (30%) medical students. ‘Work-life balance’ was the main reason cited for not wishing to pursue surgery (29/46 (63%) medical students and 25/50 (50%) junior doctors). 28/46 (61%) medical students and 28/50 (56%) junior doctors had encountered a female surgical role model; only five students and two junior doctors felt that these were influential in their career decision. Of those who had not, approximately 40% in each group felt that if they had, they may have considered surgery. Approximately 30% in each group had encountered female surgeons that had dissuaded them from a surgical career.

Conclusions

Work-life balance is still cited by female junior doctors as being the main deterrent to a surgical career. The paucity of female role models and some perceived sexual discrimination may cause female doctors to discount surgery as a career.
Inhibition of Akt2 phosphorylation abolishes the calorie restriction-induced improvement in insulin-stimulated glucose uptake by rat soleus muscle
Authors: Sharma Naveen , Arias Edward B. , Cartee Gregory D.
Published: August 2016

Calorie restriction (CR; ∼60%–65% of ad libitum consumption) can enhance insulin-stimulated glucose uptake (ISGU) in predominantly slow-twitch skeletal muscles (e.g., soleus) by an incompletely understood mechanism. We used an Akt inhibitor (MK-2206) to eliminate CR’s effect on insulin-stimulated Akt2 phosphorylation in isolated rat soleus muscles. We found long-term CR-enhanced ISGU was abolished by eliminating the CR effect on Akt2 phosphorylation, suggesting the CR-induced benefit on ISGU in the predominantly slow-twitch soleus relies on enhanced Akt2 phosphorylation.
Assessing the penetration resistance acting on a dynamically installed anchor in normally consolidated and overconsolidated clay
Authors: O’Beirne C. , O’Loughlin C.D. , Gaudin C.
Published: August 2016

Predicting the final embedment depth of a dynamically installed anchor is a key prerequisite for reliable calculation of anchor capacity. This paper investigates the embedment characteristics of dynamically installed anchors in normally consolidated and overconsolidated clay through a series of centrifuge tests involving a model anchor instrumented with a microelectric mechanical system (MEMS) accelerometer, enabling the full motion response of the anchor to be established. The data are used to assess the performance of an anchor embedment model based on strain-rate-dependent shearing resistance and fluid mechanics drag resistance. Predictions of a database of over 100 anchor installations — formed from this study and the literature — result in calculated anchor embedment depths that are within ±15% of the measurements. An interesting aspect, consistent across the entire database, relates to the strain rate dependence on frictional resistance relative to bearing resistance. The predictions reveal that strain rate dependency may indeed be higher for frictional resistance, although only if a soil strength lower than the fully remoulded strength is considered as the reference strength, which suggests that water may be entrained along a boundary layer at the anchor–soil interface during installation.
Synergistic interaction between diclofenac and pyrilamine on nociception, inflammation, and gastric damage in rats
Authors: Ortiz Mario I.
Published: August 2016

Experiments using nonsteroidal anti-inflammatory drugs (NSAIDs) alone have produced limited antinociceptive effects in animal models. For this reason, the number of studies involving the administration of NSAIDs along with an adjuvant drug harboring different mechanisms of action has increased enormously. Here, combinations of diclofenac and pyrilamine were used to determine their influence on nociception (formalin test), inflammation (paw inflammation produced by carrageenan), and gastric damage in rodents. Diclofenac, pyrilamine, or combinations of diclofenac and pyrilamine produced antinociceptive and anti-inflammatory effects in the rat. The systemic administration of diclofenac alone and in combination with pyrilamine produced significant gastric damage. Effective dose (ED) values were determined for each individual drug, and isobolograms were prepared. The theoretical ED values for the antinociceptive (systemic, 35.4 mg/kg; local, 343.4 μg/paw) and the anti-inflammatory (37.9 mg/kg) effects differed significantly from the experimental ED values (systemic antinociception, 18.1 mg/kg; local antinociception, 183.3 μg/paw; anti-inflammation, 10.6 mg/kg). Therefore, it was concluded that the interactions between diclofenac and pyrilamine are synergistic. The data suggest that the diclofenac–pyrilamine combinations can interact at the systemic and local peripheral levels, thereby offering a therapeutic alternative for the clinical management of inflammatory pain.
Review of neutrino oscillations with sterile and active neutrinos
Authors: Kisslinger Leonard S.
Published: August 2016

Recently neutrino oscillation experiments have shown that it is very likely that there are one or two sterile neutrinos. In this review neutrino oscillations with one, two, three sterile and three active neutrinos, and parameters that are consistent with experiments, are reviewed.
Simulation on a novel micron-array inertial impactor for submicron and ultrafine particle separation
Authors: Liu Rui-Tao , Tao Lu-Qi , Yang Yi , Ren Tian-Ling
Published: August 2016

The particulate matter (PM), which was put forward in 1997 by US, had taken more and more attention due to the influence on human health. Although the mass concentration, number concentration and chemical composition of PM were still major research directions, how to collect these PMs more efficiently becomes critical. Inertial impactor is an effective separation device, however, due to different motion states of PM[Formula: see text] and PM[Formula: see text] in the flow field, the inertial impactor which can separate PM[Formula: see text] from other PMs has not been fabricated. In this work, the motion states for both submicron and ultrafine particles were studied by using classical theory of channel aerodynamic, and a novel micron-array inertial impactor was designed and simulated for the first time. Besides, the influence of some characteristic parameters (W, T, S, Dc, etc.) on particle collection efficiency were researched and discussed through simulation results. This novel structure can be easily fabricated by MEMS technology or laser direct writing and also can be widely used in particle separation or flexible sensor fields.
Localized surface plasmon resonance modes on an asymmetric cylindrical nanorod dimer
Authors: Wang Rui-Bing , Zhang Zhi-Dong , Jiao Guo-Tai , Xue Chen-Yang , Yan Shu-Bin , Wang Hongyang
Published: August 2016

The extinction spectra and electric field distribution of an asymmetric cylindrical nanorod dimer (ACND) are calculated by discrete dipole approximation. The ACND is composed of two linear orders of cylindrical silver nanorods with different radii and lengths. The effects of the structural parameters of ACND on the localized surface plasmon resonance (LSPR) mode are also studied. Results show two resonance peaks in the extinction spectra of ACND: the higher-energy anti-bonding mode and the lower-energy bonding mode. The interaction of two hybridization plasmonic resonance modes produces an asymmetric line shape in the extinction spectra, which is considered to be a Fano resonance profile.
The Nernst effect in layered superconductors under a magnetic field
Authors: Tinh Bui Duc , Thu Le Minh , Hoc Nguyen Quang
Published: August 2016

We calculated the Nernst signal [Formula: see text], describing the Nernst effect in type-II superconductor in the vortex–liquid regime, by using the time-dependent Ginzburg–Landau (TDGL) equation with thermal noise. The nonlinear interaction term in the TDGL equation is treated within self-consistent Gaussian approximation. The expression of the Nernst signal [Formula: see text] including all the Landau levels is presented in explicit form which is applicable essentially to the whole phase. Our results are compared with the recent experimental data on high-[Formula: see text] superconductor.
The stability of portfolio investment in stock crashes
Authors: Li Yun-Xian , Qian Zhen-Wei , Li Jiang-Cheng , Tang Nian-Sheng , Mei Dong-Cheng
Published: August 2016

The stability of portfolio investment in stock market crashes with Markowitz portfolio is investigated by the method of theoretical and empirical simulation. From numerical simulation of the mean escape time (MET), we conclude that: (i) The increasing number [Formula: see text] of stocks in Markowitz portfolio induces a maximum in the curve of MET versus the initial position; (ii) A critical value of [Formula: see text] in the behavior of MET versus the long-run variance or amplitude of volatility fluctuations maximumlly enhances the stability of portfolio investment. When [Formula: see text] takes value below the critical value, the increasing [Formula: see text] enhances the stability of portfolio investment, but restrains it when [Formula: see text] takes value above the critical value. In addition, a good agreement of both the MET and probability density functions of returns is found between real data and theoretical results.
Using General-Purpose Serial-Link Manipulators for Laparoscopic Surgery with Moving Remote Center of Motion
Authors: Marinho Murilo M. , Bernardes Mariana C. , Bo Antonio P. L.
Published: August 2016

Minimally invasive surgical systems are being widely used to aid operating rooms across the globe. Although arguably successful in laparoscopic surgery, the da Vinci robotic system has limitations mostly regarding cost and lack of patient physiological motion compensation. To obtain a more cost-effective alternative, earlier works used general-purpose fully actuated serial-link robots to control instruments in laparoscopic research using constrained Jacobian techniques. In contrast with those works, we present a new technique to solve the laparoscopic constraints for the serial-link manipulator by using a constrained trajectory. This novel technique allows complex 3D remote center-of-motion trajectories to be taken into account. Moreover, it does not have problems related to drifting, and is less prone to singularity related issues as it can be used with redundant manipulators. The proof-of-concept experiments are done by performing artificial trajectories with static and moving trocar points using a physical robot manipulator. Furthermore, the system is tested using user input of 13 medically untrained personnel in an endoscope navigation task. The experiments show that the system can be operated reliably under arbitrary and unpredictable user inputs.
Practices as a unit of design
Authors: Kuijer Lenneke , Jong Annelise de , Eijk Daan van
Published: August 2016

The sustainability challenges facing society today require approaches that look beyond single product-user interactions. Focusing on socially shared practices—e.g. cooking, laundering—has been identified as a promising direction. Building on a growing body of research in sustainable HCI that takes practices as unit of analysis, this article explores what it means to take practices as a unit of design. Drawing on theories of practice, it proposes that practice-oriented design approaches should: involve bodily performance, create crises of routine and generate a variety of performances. These guidelines were integrated into a Generative Improv Performances (GIP) approach, entailing a series of performances by improvisation actors with low-fidelity prototypes in a lab environment. The approach was implemented in an empirical study on bathing. Although the empirical example does not deal with common types of interactive technologies, the guidelines and GIP approach offer sustainable HCI a way to think beyond immediate interactions and to conceptualize change on a practice level.
Walking and the social life of solar charging in rural africa
Authors: Bidwell Nicola J. , Siya Masbulele , Marsden Gary , Tucker William D. , Tshemese M. , Gaven N. , Ntlangano S. , Robinson Simon , Eglinton Kristen ALI
Published: August 2016

We consider practices that sustain social and physical environments beyond those dominating sustainable HCI discourse. We describe links between walking, sociality, and using resources in a case study of community-based, solar, cellphone charging in villages in South Africa's Eastern Cape. Like 360 million rural Africans, inhabitants of these villages are poor and, like 25% and 92% of the world, respectively, do not have domestic electricity or own motor vehicles. We describe nine practices in using the charging stations we deployed. We recorded 700 people using the stations, over a year, some regularly. We suggest that the way we frame practices limits insights about them, and consider various routines in using and sharing local resources to discover relations that might also feature in charging. Specifically, walking interconnects routines in using, storing, sharing and sustaining resources, and contributes to knowing, feeling, wanting and avoiding as well as to different aspects of sociality, social order and perspectives on sustainability. Along the way, bodies acquire literacies that make certain relationalities legible. Our study shows we cannot assert what sustainable practice means a priori and, further, that detaching practices from bodies and their paths limits solutions, at least in rural Africa. Thus, we advocate a more “alongly” integrated approach to data about practices.
Applying the lens of sensory ethnography to sustainable HCI
Authors: Pink Sarah , Mackley Kerstin Leder , Mitchell Val , Hanratty Marcus , Escobar-Tello Carolina , Bhamra Tracy , Morosanu Roxana
Published: August 2016

Sociological appropriations of practice theory as applied to sustainable design have successfully problematized overly simplistic and individualistic models of consumer choice and behavior change. By taking everyday practices as the principal units of analysis, they move towards acknowledging the socially and materially structured nature of human activity. However, to inform sustainable HCI we also need to understand how practices are part of wider experiential environments and flows of practical activity. In this article, we develop an approach rooted in phenomenological anthropology and sensory ethnography. This approach builds on theories of place, perception and movement and enables us to situate practices, and understand practical activity, as emplaced within complex and shifting ecologies of things. Drawing on an interdisciplinary study of domestic energy consumption and digital media use, we discuss ethnographic and design practice examples. We demonstrate how this theoretical and methodological framework can be aligned with the 3rd paradigm of HCI.
Data Structures for Path Queries
Authors: He Meng , Munro J. Ian , Zhou Gelin
Published: August 2016

Consider a tree
T
on
n
nodes, each having a weight drawn from [1‥σ]. In this article, we study the problem of supporting various path queries over the tree
T
. The path counting query asks for the number of the nodes on a query path whose weights are in a query range, while the path reporting query requires to report these nodes. The path median query asks for the median weight on a path between two given nodes, and the path selection query returns the
k
-th smallest weight. We design succinct data structures to encode
T
using n
nH
(

W
T

) + 2
n
+
o
(
n
lg σ) bits of space, such that we can support path counting queries in
O
(lg σ/lg lg
n
+ 1)) time, path reporting queries in
O
((
occ
+1)(lg σ / lg lg
n
+ 1)) time, and path median and path selection queries in
O
(lg σ / lg lg σ) time, where
H
(

W
T

) is the entropy of the multiset of the weights of the nodes in
T
and
occ
is the size of the output. Our results not only greatly improve the best known data structures [Chazelle 1987; Krizanc et al. 2005], but also match the lower bounds for path counting, median, and selection queries [Pătraşcu 2007, 2011; Jørgensen and Larsen 2011] when σ = Ω(
n
/polylog(
n
)).
Pipelined Iterative Solvers with Kernel Fusion for Graphics Processing Units
Authors: Rupp Karl , Weinbub Josef , Jüngel Ansgar , Grasser Tibor
Published: August 2016

We revisit the implementation of iterative solvers on discrete graphics processing units and demonstrate the benefit of implementations using extensive kernel fusion for pipelined formulations over conventional implementations of classical formulations. The proposed implementations with both CUDA and OpenCL are freely available in ViennaCL and are shown to be competitive with or even superior to other solver packages for graphics processing units. The highest-performance gains are obtained for small to medium-sized systems, while our implementations are on par with vendor-tuned implementations for very large systems. Our results are especially beneficial for transient problems, where many small to medium-sized systems instead of a single big system need to be solved.
Scalable and Efficient Web Search Result Diversification
Authors: Naini Kaweh Djafari , Altingovde Ismail Sengor , Siberski Wolf
Published: August 2016

It has been shown that top-
k
retrieval quality can be considerably improved by taking not only relevance but also diversity into account. However, currently proposed diversification approaches have not put much attention on practical usability in large-scale settings, such as modern web search systems. In this work, we make two contributions toward this goal. First, we propose a combination of optimizations and heuristics for an implicit diversification algorithm based on the desirable facility placement principle, and present two algorithms that achieve linear complexity without compromising the retrieval effectiveness. Instead of an exhaustive comparison of documents, these algorithms first perform a clustering phase and then exploit its outcome to compose the diverse result set. Second, we describe and analyze two variants for distributed diversification in a computing cluster, for large-scale IR where the document collection is too large to keep in one node. Our contribution in this direction is pioneering, as there exists no earlier work in the literature that investigates the effectiveness and efficiency of diversification on a distributed setup. Extensive evaluations on a standard TREC framework demonstrate a competitive retrieval quality of the proposed optimizations to the baseline algorithm while reducing the processing time by more than 80% and up to 97%, and shed light on the efficiency and effectiveness tradeoffs of diversification when applied on top of a distributed architecture.
Analytical Modeling Is Enough for High-Performance BLIS
Authors: Low Tze Meng , Igual Francisco D. , Smith Tyler M. , Quintana-Orti Enrique S.
Published: August 2016

We show how the BLAS-like Library Instantiation Software (BLIS) framework, which provides a more detailed layering of the GotoBLAS (now maintained as OpenBLAS) implementation, allows one to analytically determine tuning parameters for high-end instantiations of the matrix-matrix multiplication. This is of both practical and scientific importance, as it greatly reduces the development effort required for the implementation of the level-3 BLAS while also advancing our understanding of how hierarchically layered memories interact with high-performance software. This allows the community to move on from valuable engineering solutions (empirically autotuning) to scientific understanding (analytical insight).
Optimal Contest Design for Simple Agents
Authors: Ghosh Arpita , Kleinberg Robert
Published: August 2016

Incentives are more likely to elicit desired outcomes when they are designed based on accurate models of agents’ strategic behavior. A growing literature, however, suggests that people do not quite behave like standard economic agents in a variety of environments, both online and offline. What consequences might such differences have for the optimal design of mechanisms in these environments? In this article, we explore this question in the context of optimal contest design for
simple
agents—agents who strategically reason about whether or not to participate in a system, but not about the input they provide to it. Specifically, consider a contest where
n
potential contestants with types (

q
i

,

c
i

) each choose between participating and producing a submission of quality

q
i

at cost

c
i

, versus not participating at all to maximize their utilities. How should a principal distribute a total prize
V
among the
n
ranks to maximize some increasing function of the qualities of elicited submissions in a contest with such simple agents?

We first solve the optimal contest design problem for settings where agents have homogenous participation costs

c
i

=
c
. Here, the contest that maximizes every increasing function of the elicited contributions is always a simple contest, awarding equal prizes of
V
/
j
* each to the top
j
*=
V
/
c
− Θ(√
V
/(
c
ln (
V
/
c
))) contestants. This is in contrast to the optimal contest structure in comparable models with strategic effort choices, where the optimal contest is either a winner-take-all contest or awards possibly unequal prizes, depending on the curvature of agents’ effort cost functions. We next address the general case with heterogenous costs where agents’ types (

q
i

,

c
i

) are inherently two dimensional, significantly complicating equilibrium analysis. With heterogenous costs, the optimal contest depends on the objective being maximized: our main result here is that the winner-take-all contest is a 3-approximation of the optimal contest when the principal’s objective is to maximize the quality of the best elicited contribution. The proof of this result hinges around a “subequilibrium” lemma establishing a stochastic dominance relation between the distribution of qualities elicited in an equilibrium and a
subequilibrium
—a strategy profile that is a best response for all agents who choose to participate in that strategy profile; this relation between equilibria and subequilibria may be of more general interest.
A Comprehensive Survey and Classification of Approaches for Community Question Answering
Authors: Srba Ivan , Bielikova Maria
Published: August 2016

Community question-answering (CQA) systems, such as Yahoo! Answers or Stack Overflow, belong to a prominent group of successful and popular Web 2.0 applications, which are used every day by millions of users to find an answer on complex, subjective, or context-dependent questions. In order to obtain answers effectively, CQA systems should optimally harness collective intelligence of the whole online community, which will be impossible without appropriate collaboration support provided by information technologies. Therefore, CQA became an interesting and promising subject of research in computer science and now we can gather the results of 10 years of research. Nevertheless, in spite of the increasing number of publications emerging each year, so far the research on CQA systems has missed a comprehensive state-of-the-art survey. We attempt to fill this gap by a review of 265 articles published between 2005 and 2014, which were selected from major conferences and journals. According to this evaluation, at first we propose a framework that defines descriptive attributes of CQA approaches. Second, we introduce a classification of all approaches with respect to problems they are aimed to solve. The classification is consequently employed in a review of a significant number of representative approaches, which are described by means of attributes from the descriptive framework. As a part of the survey, we also depict the current trends as well as highlight the areas that require further attention from the research community.
FlexDPDP
Authors: Esiner Ertem , Kachkeev Adilet , Braunfeld Samuel , Küpçü Alptekin , Özkasap Öznur
Published: August 2016

With increasing popularity of cloud storage, efficiently proving the integrity of data stored on an untrusted server has become significant. Authenticated skip lists and rank-based authenticated skip lists (RBASL) have been used to provide support for provable data update operations in cloud storage. However, in a dynamic file scenario, an RBASL based on block indices falls short when updates are not proportional to a fixed block size; such an update to the file, even if small, may result in
O
(
n
) updates on the data structure for a file with
n
blocks.

To overcome this problem, we introduce FlexList, a flexible length-based authenticated skip list. FlexList translates variable-size updates to
O
(⌈ u/B ⌉) insertions, removals, or modifications, where
u
is the size of the update and
B
is the (average) block size. We further present various optimizations on the four types of skip lists (regular, authenticated, rank-based authenticated, and FlexList). We build such a structure in
O
(
n
) time and parallelize this operation for the first time. We compute one single proof to answer multiple (non)membership queries and obtain efficiency gains of 35%, 35%, and 40% in terms of proof time, energy, and size, respectively. We propose a method of handling multiple updates at once, achieving efficiency gains of up to 60% at the server side and 90% at the client side. We also deployed our implementation of FlexDPDP (dynamic provable data possession (DPDP) with FlexList instead of RBASL) on PlanetLab, demonstrating that FlexDPDP performs comparable to the most efficient static storage scheme (provable data possession (PDP)) while providing dynamic data support.
Prediction and Predictability for Search Query Acceleration
Authors: Hwang Seung-Won , Kim Saehoon , He Yuxiong , Elnikety Sameh , Choi Seungjin
Published: August 2016

A commercial web search engine shards its index among many servers, and therefore the response time of a search query is dominated by the slowest server that processes the query. Prior approaches target improving responsiveness by reducing the
tail latency
, or high-percentile response time, of an individual search server. They predict query execution time, and if a query is predicted to be long-running, it runs in parallel; otherwise, it runs sequentially. These approaches are, however, not accurate enough for reducing a high tail latency when responses are aggregated from many servers because this requires each server to reduce a substantially higher tail latency (e.g., the 99.99th percentile), which we call extreme tail latency.

To address tighter requirements of
extreme
tail latency, we propose a new
design space
for the problem, subsuming existing work and also proposing a new solution space. Existing work makes a prediction using features available at indexing time and focuses on optimizing prediction features for accelerating tail queries. In contrast, we identify “when to predict?” as another key optimization question. This opens up a new solution of delaying a prediction by a short duration to allow many short-running queries to complete without parallelization and, at the same time, to allow the predictor to collect a set of dynamic features using runtime information. This new question expands a solution space in two meaningful ways. First, we see a significant reduction of tail latency by leveraging “dynamic” features collected at runtime that estimate query execution time with higher accuracy. Second, we can ask whether to override prediction when the “predictability” is low. We show that considering predictability accelerates the query by achieving a higher recall.

With this prediction, we propose to accelerate the queries that are predicted to be long-running. In our preliminary work, we focused on parallelization as an acceleration scenario. We extend to consider heterogeneous multicore hardware for acceleration. This hardware combines processor cores with different microarchitectures such as energy-efficient little cores and high-performance big cores, and accelerating web search using this hardware has remained an open problem.

We evaluate the proposed prediction framework in two scenarios: (1) query parallelization on a multicore processor and (2) query scheduling on a heterogeneous processor. Our extensive evaluation results show that, for both scenarios of query acceleration using parallelization and heterogeneous cores, the proposed framework is effective in reducing the extreme tail latency compared to a start-of-the-art predictor because of its higher recall, and it improves server throughput by more than 70% because of its improved precision.