bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical and Molecular Characteristics of Emerging Hypervirulent Klebsiella pneumoniae Bloodstream Infections in Mainland China
Authors: Liu Ying Mei , Li Bin Bin , Zhang Yu Yu , Zhang Wu , Shen Hong , Li Hui , Cao Bin
Published: July 2014

Recently, the newly emerged hypervirulent
Klebsiella pneumoniae
strain (hvKP) has caused great concern globally, but the clinical features and molecular characteristics of bacteremia caused by hvKP are rarely reported in mainland China. Seventy patients with
K. pneumoniae
bacteremia were investigated to study the clinical features of hvKP infection from 2008 till 2012 in Beijing Chao-Yang Hospital. The molecular characteristics of the hvKP strains were also studied using PCR, multilocus sequence typing, and pulsed-field gel electrophoresis (PFGE) methods. hvKP was identified in 31.4% of the patients with
K. pneumoniae
bacteremia, which displayed 4 serotypes (K1, K2, K20, and K57). Patients with hvKP infection tended to have no underlying diseases compared to those with classic
K. pneumoniae
(cKP). More hvKP-positive patients (95.5%) had community-acquired infection than did cKP-infected patients (35.4%) (
P
< 0.001). The 30-day mortality rate was lower in hvKP-infected patients than in cKP-infected patients (4.5% compared to 16.7%). Resistance to tested antimicrobials was significantly greater in cKP- than in hvKP-infected patients. Two extended-spectrum-beta-lactamase (ESBL)-producing hvKP strains were found. Seven novel sequence types (STs) and 4 new alleles of
K. pneumoniae
were revealed. A strong correlation was found between two STs (ST23, ST1265) and the K1 serotype. The hvKP isolates (
n
= 22) had 14 different PFGE patterns, and among them 10 K1 isolates shared similar PFGE patterns. The emerging hvKP strain was prevalent in patients with severe community-acquired infections in healthy individuals in China. Identification of ESBL-producing hvKP strains in hvKP-infected patients will facilitate clinical management of hvKP infection.
NDM-5 Carbapenemase-Encoding Gene in Multidrug-Resistant Clinical Isolates of Escherichia coli from Algeria
Authors: Sassi Asma , Loucif Lotfi , Gupta Sushim Kumar , Dekhil Mazouz , Chettibi Houria , Rolain Jean-Marc
Published: July 2014

Here, we report the first autochthonous cases of infections caused by
bla
NDM-5
New Delhi metallo-β-lactamase-producing
Escherichia coli
strains recovered from urine and blood specimens of three patients from Algeria between January 2012 and February 2013. The three isolates belong to sequence type 2659 and they coexpress
bla
CTX-M-15
with the
bla
TEM-1
and
bla
aadA2
genes.
In Vitro
and
In Vivo
Activities of Antimicrobial Peptides Developed Using an Amino Acid-Based Activity Prediction Method
Authors: Wu Xiaozhe , Wang Zhenling , Li Xiaolu , Fan Yingzi , He Gu , Wan Yang , Yu Chaoheng , Tang Jianying , Li Meng , Zhang Xian , Zhang Hailong , Xiang Rong , Pan Ying , Liu Yan , Lu Lian , Yang Li
Published: July 2014

To design and discover new antimicrobial peptides (AMPs) with high levels of antimicrobial activity, a number of machine-learning methods and prediction methods have been developed. Here, we present a new prediction method that can identify novel AMPs that are highly similar in sequence to known peptides but offer improved antimicrobial activity along with lower host cytotoxicity. Using previously generated AMP amino acid substitution data, we developed an amino acid activity contribution matrix that contained an activity contribution value for each amino acid in each position of the model peptide. A series of AMPs were designed with this method. After evaluating the antimicrobial activities of these novel AMPs against both Gram-positive and Gram-negative bacterial strains, DP7 was chosen for further analysis. Compared to the parent peptide HH2, this novel AMP showed broad-spectrum, improved antimicrobial activity, and in a cytotoxicity assay it showed lower toxicity against human cells. The
in vivo
antimicrobial activity of DP7 was tested in a
Staphylococcus aureus
infection murine model. When inoculated and treated via intraperitoneal injection, DP7 reduced the bacterial load in the peritoneal lavage solution. Electron microscope imaging and the results indicated disruption of the
S. aureus
outer membrane by DP7. Our new prediction method can therefore be employed to identify AMPs possessing minor amino acid differences with improved antimicrobial activities, potentially increasing the therapeutic agents available to combat multidrug-resistant infections.
In Vitro
Activities of Nine Antifungal Drugs and Their Combinations against Phialophora verrucosa
Authors: Li Yali , Wan Zhe , Li Ruoyu
Published: July 2014

The
in vitro
activities of nine antifungal drugs and their combinations against 31 clinical and 15 environmental
Phialophora verrucosa
strains were tested. The MIC
90
/90% minimum effective concentration (MIC/MEC
90
) values (μg/ml) across all strains were as follows: for terbinafine, 0.25; for posaconazole, 0.5; for voriconazole, 1; for itraconazole, 2; for amphotericin B, 4; for caspofungin and micafungin, 16; and for fluconazole and flucytosine, 64. The highest synergy was shown by the combination of itraconazole plus caspofungin (with synergy against 100% of the 31 clinical strains), followed by amphotericin B plus flucytosine (45.2%) and itraconazole plus terbinafine or micafungin (25.8% or 12.9%, respectively).
In Vitro
Antifungal Susceptibility Profile and Correlation of Mycelial and Yeast Forms of Molecularly Characterized Histoplasma capsulatum Strains from India
Authors: Kathuria Shallu , Singh Pradeep K. , Meis Jacques F. , Chowdhary Anuradha
Published: July 2014

The antifungal susceptibility profiles of the mycelial and yeast forms of 23
Histoplasma capsulatum
strains from pulmonary and disseminated histoplasmosis patients in India are reported here. The MIC data of this dimorphic fungus had good agreement between both forms for azoles, amphotericin B, and caspofungin. Therefore, the use of mycelial inocula for
H. capsulatum
antifungal susceptibility testing is suggested, which is less time-consuming vis-à-vis the yeast form, which requires 6 to 8 weeks for conversion.
Emergence of Multidrug-Resistant Campylobacter Species Isolates with a Horizontally Acquired rRNA Methylase
Authors: Wang Yang , Zhang Maojun , Deng Fengru , Shen Zhangqi , Wu Congming , Zhang Jianzhong , Zhang Qijing , Shen Jianzhong
Published: July 2014

Antibiotic-resistantCampylobacterconstitutes a serious threat to public health, and resistance to macrolides is of particular concern, as this class of antibiotics is the drug of choice for clinical therapy of campylobacteriosis. Very recently, a horizontally transferrable macrolide resistance mediated by the rRNA methylase geneerm(B) was reported in aCampylobacter coliisolate, but little is known about the dissemination oferm(B) amongCampylobacterisolates and the association oferm(B)-carrying isolates with clinical disease. To address this question and facilitate the control of antibiotic-resistantCampylobacter, we determined the distribution oferm(B) in 1,554C. coliandCampylobacter jejuniisolates derived from food-producing animals and clinically confirmed human diarrheal cases. The results revealed that 58 of the examined isolates harborederm(B) and exhibited high-level resistance to macrolides, and most were recent isolates, derived in 2011-2012. In addition, theerm(B)-positive isolates were all resistant to fluoroquinolones, another clinically important antibiotic used for treating campylobacteriosis. Theerm(B) gene is found to be associated with chromosomal multidrug resistance genomic islands (MDRGIs) of Gram-positive origin or with plasmids of various sizes. All MDRGIs were transferrable to macrolide-susceptibleC. jejuniby natural transformation under laboratory conditions. Molecular typing of theerm(B)-carrying isolates by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) identified diverse genotypes and outbreak-associated diarrheal isolates. Molecular typing also suggested zoonotic transmission oferm(B)-positiveCampylobacter. These findings reveal an emerging and alarming trend of dissemination oferm(B) and MDRGIs inCampylobacterand underscore the need for heightened efforts to control their further spread.
Genotypic and Phenotypic Analyses of Hepatitis C Virus Variants Observed in Clinical Studies of VX-222, a Nonnucleoside NS5B Polymerase Inhibitor
Authors: Jiang Min , Zhang Eileen Z. , Ardzinski Andrzej , Tigges Ann , Davis Andrew , Sullivan James C. , Nelson Michelle , Spanks Joan , Dorrian Jennifer , Nicolas Olivier , Bartels Doug J. , Rao B. Govinda , Rijnbrand Rene , Kieffer Tara L.
Published: July 2014

VX-222, a thiophene-2-carboxylic acid derivative, is a selective nonnucleoside inhibitor of the hepatitis C virus (HCV) NS5B RNA-dependent RNA polymerase. In phase 1 and 2 clinical studies, VX-222 demonstrated effective antiviral efficacy, with substantial reductions in plasma HCV RNA in patients chronically infected with genotype 1 HCV. To characterize the potential for selection of VX-222-resistant variants in HCV-infected patients, the HCV NS5B gene was sequenced at baseline and during and after 3 days of VX-222 dosing (monotherapy) in a phase 1 study. Variants with the substitutions L419C/I/M/P/S/V, R422K, M423I/T/V, I482L/N/T, A486S/T/V, and V494A were selected during VX-222 dosing, and their levels declined over time after the end of dosing. Phenotypic analysis of these variants was conducted using HCV replicons carrying site-directed mutations. Of the 17 variants, 14 showed reduced susceptibility to VX-222 compared with the wild type, with the L419C/S and R422K variants having higher levels of resistance (>200-fold) than the rest of the variants (6.8- to 76-fold). The M423I and A486S variants remained susceptible to VX-222. The 50% effective concentration (EC
50
) for the L419P variant could not be obtained due to the poor replication of this replicon. The majority of the variants (15/17) were less fit than the wild type. A subset of the variants, predominately the L419S and R422K variants, were observed when the efficacy and safety of VX-222- and telaprevir-based regimens given for 12 weeks were investigated in genotype 1 HCV-infected patients in a phase 2 study. The NS3 and NS5B variants selected during the dual combination therapy showed reduced susceptibility to both telaprevir and VX-222 and had a lower replication capacity than the wild type. The phase 1b study has the ClinicalTrials.gov identifier NCT00911963, and the phase 2a study has ClinicalTrials.gov identifier NCT01080222.
Quasi-Experimental Study of Sodium Citrate Locks and the Risk of Acute Hemodialysis Catheter Infection among Critically Ill Patients
Authors: Parienti Jean-Jacques , Deryckère Stéphanie , Mégarbane Bruno , Valette Xavier , Seguin Amélie , Sauneuf Bertrand , Mira Jean-Paul , Souweine Bertrand , Cattoir Vincent , Daubin Cédric , du Cheyron Damien
Published: July 2014

Critically ill patients who require renal replacement therapy (RRT) are vulnerable to catheter-related bloodstream infections (CRBSI). This study compared the risks of dialysis catheter infection according to the choice of locking solution in the intensive care unit (ICU). A prospective quasi-experimental study with marginal structural models (MSM) and 2:1 greedy propensity-score matching (PSM) was conducted at nine university-affiliated hospitals and three general hospitals. A total of 596 critically ill patients received either saline solution or heparin lock solution (the standard of care [SOC]) from 2004 to 2007 in the Cathedia cohort (
n
= 464 for MSM;
n
= 124 for PSM) or 46.7% citrate lock from 2011 to 2012 in the citrate (CLock) cohort (
n
= 132 for MSM;
n
= 62 for PSM) to perform RRT using intermittent hemodialysis. Catheter-tip colonization and CRBSI were analyzed. The mean duration (standard deviation [SD]) of catheterization was 7.1 days (6.1) in the SOC group and 7.0 days (5.9) in the CLock group (
P
= 0.84). The risk of dialysis catheter-tip colonization was lower in the CLock group (20.5 versus 38.7 per 1,000 catheter-days in the SOC group; hazard ratio [HR] from MSM, 0.73; 95% confidence interval [CI], 0.57 to 0.93;
P
< 0.02). Consistent findings were found from PSM (HR, 0.46; 95% CI, 0.22 to 0.95;
P
< 0.04). The risk of CRBSI was nonsignificantly different in the CLock group (1.1 versus 1.8 per 1,000 catheter-days in the SOC group; HR from MSM, 0.48; 95% CI, 0.12 to 1.87;
P
= 0.29). By reducing the risk of catheter-tip colonization, citrate lock has the potential to improve hemodialysis safety in the ICU. Additional studies are warranted before the routine use of citrate locks can be recommended in the ICU.
A Broad-Spectrum Antibiofilm Peptide Enhances Antibiotic Action against Bacterial Biofilms
Authors: Reffuveille Fany , de la Fuente-Núñez César , Mansour Sarah , Hancock Robert E. W.
Published: July 2014

Biofilm-related infections account for at least 65% of all human infections, but there are no available antimicrobials that specifically target biofilms. Their elimination by available treatments is inefficient since biofilm cells are between 10- and 1,000-fold more resistant to conventional antibiotics than planktonic cells. Here we describe the synergistic interactions, with different classes of antibiotics, of a recently characterized antibiofilm peptide, 1018, to potently prevent and eradicate bacterial biofilms formed by multidrug-resistant ESKAPE (
Enterococcus faecium
,
Staphylococcus aureus
,
Klebsiella pneumoniae
,
Acinetobacter baumannii
,
Pseudomonas aeruginosa
, and
Enterobacter
species) pathogens. Combinations of peptide 1018 and the antibiotic ceftazidime, ciprofloxacin, imipenem, or tobramycin were synergistic in 50% of assessments and decreased by 2- to 64-fold the concentration of antibiotic required to treat biofilms formed by
Pseudomonas aeruginosa
,
Escherichia coli
,
Acinetobacter baumannii
,
Klebsiella pneumoniae
,
Salmonella enterica
, and methicillin-resistant
Staphylococcus aureus
. Furthermore, in flow cell biofilm studies, combinations of low, subinhibitory levels of the peptide (0.8 μg/ml) and ciprofloxacin (40 ng/ml) decreased dispersal and triggered cell death in mature
P. aeruginosa
biofilms. In addition, short-term treatments with the peptide in combination with ciprofloxacin prevented biofilm formation and reduced
P. aeruginosa
PA14 preexisting biofilms. PCR studies indicated that the peptide suppressed the expression of various antibiotic targets in biofilm cells. Thus, treatment with the peptide represents a novel strategy to potentiate antibiotic activity against biofilms formed by multidrug-resistant pathogens.
Bacterial Siderophores That Evade or Overwhelm Lipocalin 2 Induce Hypoxia Inducible Factor 1α and Proinflammatory Cytokine Secretion in Cultured Respiratory Epithelial Cells
Authors: Holden Victoria I. , Lenio Steven , Kuick Rork , Ramakrishnan Sadeesh K. , Shah Yatrik M. , Bachman Michael A.
Published: July 2014

Iron is essential for many cellular processes and is required by bacteria for replication. To acquire iron from the host, pathogenic Gram-negative bacteria secrete siderophores, including enterobactin (Ent). However, Ent is bound by the host protein lipocalin 2 (Lcn2), preventing bacterial reuptake of aferric or ferric Ent. Furthermore, the combination of Ent and Lcn2 (Ent+Lcn2) leads to enhanced secretion of interleukin-8 (IL-8) compared to that induced by either stimulus alone. Modified or structurally distinct siderophores, including yersiniabactin (Ybt) and glycosylated Ent (GlyEnt, or salmochelin), deliver iron to bacteria despite the presence of Lcn2. We hypothesized that the robust immune response to Ent and Lcn2 requires iron chelation rather than the Ent+Lcn2 complex itself and also can be stimulated by Lcn2-evasive siderophores. To test this hypothesis, cultured respiratory epithelial cells were stimulated with combinations of purified siderophores and Lcn2 and analyzed by gene expression microarrays, quantitative PCR, and cytokine immunoassays. Ent caused HIF-1α protein stabilization, induced the expression of genes regulated by hypoxia-inducible factor 1α (HIF-1α), and repressed genes involved in cell cycle and DNA replication, whereas Lcn2 induced expression of proinflammatory cytokines. Iron chelation by excess Ent or Ybt significantly increased Lcn2-induced secretion of IL-8, IL-6, and CCL20. Stabilization of HIF-1α was sufficient to enhance Lcn2-induced IL-6 secretion. These data indicate that respiratory epithelial cells can respond to bacterial siderophores that evade or overwhelm Lcn2 binding by increasing proinflammatory cytokine production.
Evidence that Intraspecific Trait Variation among Nasal Bacteria Shapes the Distribution of Staphylococcus aureus
Authors: Libberton Ben , Coates Rosanna E. , Brockhurst Michael A. , Horsburgh Malcolm J.
Published: July 2014

Nasal carriage of
Staphylococcus aureus
is a risk factor for infection, yet the bacterial determinants required for carriage are poorly defined. Interactions between
S. aureus
and other members of the bacterial flora may determine colonization and have been inferred in previous studies by using correlated species distributions. However, traits mediating species interactions are often polymorphic, suggesting that understanding how interactions structure communities requires a trait-based approach. We characterized
S. aureus
growth inhibition by the culturable bacterial aerobe consortia of 60 nasal microbiomes, and this revealed intraspecific variation in growth inhibition and that inhibitory isolates clustered within communities that were culture negative for
S. aureus
. Across microbiomes, the cumulative community-level growth inhibition was negatively associated with
S. aureus
incidence. To fully understand the ecological processes structuring microbiomes, it will be crucial to account for intraspecific variation in the traits that mediate species interactions.
Genome-Wide Analysis of the Role of Global Transcriptional Regulator GntR1 in Corynebacterium glutamicum
Authors: Tanaka Yuya , Takemoto Norihiko , Ito Terukazu , Teramoto Haruhiko , Yukawa Hideaki , Inui Masayuki
Published: July 2014

The transcriptional regulator GntR1 downregulates the genes for gluconate catabolism and pentose phosphate pathway in
Corynebacterium glutamicum
. Gluconate lowers the DNA binding affinity of GntR1, which is probably the mechanism of gluconate-dependent induction of these genes. In addition, GntR1 positively regulates
ptsG
, a gene encoding a major glucose transporter, and
pck
, a gene encoding phosphoenolpyruvate carboxykinase. Here, we searched for the new target of GntR1 on a genome-wide scale by chromatin immunoprecipitation in conjunction with microarray (ChIP-chip) analysis. This analysis identified 56
in vivo
GntR1 binding sites, of which 7 sites were previously reported. The newly identified GntR1 sites include the upstream regions of carbon metabolism genes such as
pyk
,
maeB
,
gapB
, and
icd
, encoding pyruvate kinase, malic enzyme, glyceraldehyde 3-phosphate dehydrogenase B, and isocitrate dehydrogenase, respectively. Binding of GntR1 to the promoter region of these genes was confirmed by electrophoretic mobility shift assay. The activity of the
icd
,
gapB
, and
maeB
promoters was reduced by the mutation at the GntR1 binding site, in contrast to the
pyk
promoter activity, which was increased, indicating that GntR1 is a transcriptional activator of
icd
,
gapB
, and
maeB
and is a repressor of
pyk
. Thus, it is likely that GntR1 stimulates glucose uptake by inducing the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS) gene while repressing
pyk
to increase PEP availability in the absence of gluconate. Repression of
zwf
and
gnd
may reduce the NADPH supply, which may be compensated by the induction of
maeB
and
icd
. Upregulation of
icd
,
gapB
, and
maeB
and downregulation of
pyk
by GntR1 probably support gluconeogenesis.
Implementation of clinical practices to reduce return visits within 72 h to a paediatric emergency department
Authors: Jeong Jin Hee , Hwang Seung Sik , Kim Kyuseok , Lee Jin Hee , Rhee Joong Eui , Kang Changwoo , Lee Soo Hoon , Kim Hooyoung , Im Yeon Sook , Lee Boeknam , Byeon Young Im , Lee Ji Sook
Published: July 2014

Objective

Return visits to the paediatric emergency department (PED) are an important measure of quality of healthcare and are associated with patients’ and parents’/guardians’ satisfaction. Previous studies have been limited to describing characteristics and factors related to return visits. The objectives of this study were to develop new clinical practices to reduce return visits to the PED and to see whether implementation of these practices had the desired effect.

Patients and methods

This was a controlled before-and-after study. New clinical practices were developed by analysing data for patients visiting in 2011 (before) and by surveying emergency physicians and nurses in the PED. New clinical practices were implemented between 16 July and 4 November 2012 (after). The rate of return visits and admission rates after return visits were compared between matched periods in 2011 and 2012. We also investigated return visits at three independent hospitals to overcome the limitation of the intervention application to a single hospital.

Results

The new clinical practices included five protocols: set orders for common symptoms; management plans for patients at high risk of a return visit; a daily physician feedback system; protocolised discharge instructions; early planned visits to clinics. After implementation, the rate of return visits was reduced significantly, from 4.4% to 2.6% (p<0.01). The admission rate for return visits was also reduced, but not significantly so, from 22.3% to 17.5% (p=0.37). Return visits at the other hospitals were similar or significantly increased in 2012 compared with 2011.

Conclusions

The development and implementation of clinical practices were effective in reducing return visits of paediatric patients to the ED.
New Barrett's oesophagus surveillance guidelines: significant cost savings over the next 10 years on implementation
Authors: Hewett Rhys , Chan Derek , Kang Jin-Yong , Poullis Andrew
Published: July 2014

Objective

We aimed to estimate the cost saving (over the next 10 years) by our trust implementing the new British Society of Gastroenterology (BSG) surveillance guidelines for Barrett's oesophagus (BO).

Design

Retrospective endoscopy database analysis.

Setting

Two endoscopy units of St George's Hospital NHS Trust, London.

Patients

Gastroscopy records between 2009 and 2012 were retrieved and patients with an endoscopic diagnosis of BO were identified. BO segment length was recorded and the presence (or absence) of intestinal metaplasia in the oesophageal biopsy samples was reviewed from pathology databases. Patients were then stratified into risk groups in accordance with the new BSG guidelines.

Interventions

Nil.

Main outcome measures

The projected surveillance costs using the new and the old guidelines were calculated over the next 10 years and the cost saving by the implementation of the new guidelines thus determined.

Results

The 10 year projected cost saving for our trust by implementing the new BO surveillance guidelines was £720 330 (or £72 033 per annum). Projected across the NHS, implementation of the new guidance may save £100 million over the next 10 years.

Conclusions

All trusts should review their Barrett's surveillance population and implement these new recommendations expeditiously.
Dynamics of Functionally Graded Beams on Viscoelastic Foundation
Authors: Babilio Enrico
Published: July 2014

In the present contribution, the nonlinear dynamics of beams under axial time-dependent excitation is studied. The beams, which rest on a linear viscoelastic foundation, are assumed as axially graded both in terms of geometrical and material properties. The transversal motion equation is derived under two main hypotheses, namely the beams satisfy the requirements of Euler–Bernoulli theory and undergo moderately large deflections (MLDs).
A Technique to Capture Multi-Disciplinary Tacit Knowledge During the Conceptual Design Phase of a Building Project
Authors: Pourzolfaghar Zohreh , Ibrahim Rahinah , Abdullah Rusli , Adam Nor Mariah
Published: July 2014

The construction industry is suffering from incomplete knowledge flow that results in time and cost over-runs. Many researchers believe that a large part of this problem is related to the design phase being a tacit knowledge-dominated area. Since tacitness of knowledge contributes to incomplete flow of knowledge, we posit that facilitating the conversion of tacit knowledge to explicit knowledge can improve the overall knowledge flow. Within this context, this paper analyses recognised knowledge-capturing techniques and compares them in view of the operating characteristics of the conceptual design phase. This paper proposes a new tacit knowledge-capturing technique for this phase. The outcomes include a new knowledge-capturing technique, a method for validation of the proposed technique, and recommendations on how to deal with the challenges concomitant with the application and utilisation of the proposed technique in the building industry. By proposing a combinational tacit knowledge-capturing technique, this study attempts to mitigate the impact of the potential incomplete knowledge flow during the conceptual design phase in building projects.
Formation mechanism of large subsidence sinkholes in the Lar valley in Iran
Authors: Messerklinger Sophie
Published: July 2014

Large suffusion and cover-collapse sinkholes, of up to 100 m in diameter, developed in the Lar valley in Iran. The sinkholes formed through overburden several hundred metres thick comprising coarse- and fine-grained deposits. The formation mechanism for these large sinkholes was studied based on the topography of the bedrock and on deep borehole log data. It could be determined that the large cover-collapse sinkholes are located above permeable bedrock berms and that they formed through a layer of fine-grained, cohesive soil that was both underlain and overlain by coarse-grained soil layers. The data analysis showed that suffusion from the coarse-grained layer at the bedrock and subsequent erosion of these particles through permeable zones in the bedrock to the karst channels caused settlement of these coarse-grained layers and the formation of open caverns above them, at the interface with the fine-grained layer. With continuing erosion, the caverns widened until the limit equilibrium of the fine-grained layer was reached and then collapsed to form a depression with a horizontal bottom surface, termed a cover-collapse sinkhole. An analytical model was developed for this mechanism, considering cohesive and non-cohesive soil layers. This analytical model confirmed that, for the given composition of the overburden, cover-collapse sinkholes of 80–100 m in diameter can be expected. The paper also analysed the formation mechanism of the suffusion sinkholes and it was shown that their formation took place through coarse-grained, non-cohesive formations, in this case alluvium and slope talus. Finally, it was analysed whether the formation of new cover-collapse and suffusion sinkholes after the rehabilitation of the reservoir leakage is likely.
PDVLoc
Authors: Mun Min Y. , Kim Donnie H. , Shilton Katie , Estrin Deborah , Hansen Mark , Govindan Ramesh
Published: July 2014

Location-Based Mobile Service (LBMS) is one of the most popular smartphone services. LBMS enables people to more easily connect with each other and analyze the aspects of their lives. However, sharing location data can leak people's privacy. We present PDVLoc, a controlled location data-sharing framework based on selectively sharing data through a Personal Data Vault (PDV). A PDV is a privacy architecture in which individuals retain ownership of their data. Data are routinely filtered before being shared with content-service providers, and users or data custodian services can participate in making controlled data-sharing decisions. Introducing PDVLoc gives users flexible and granular access control over their location data. We have implemented a prototype of PDVLoc and evaluated it using real location-sharing social networking applications, Google Latitude and Foursquare. Our user study of 19 participants over 20 days shows that most users find that PDVLoc is useful to manage and control their location data, and are willing to continue using PDVLoc.
Using Metrics of Curation to Evaluate Information-Based Ideation
Authors: Kerne Andruid , Webb Andrew M. , Smith Steven M. , Linder Rhema , Lupfer Nic , Qu Yin , Moeller Jon , Damaraju Sashikanth
Published: July 2014

Evaluating creativity support environments is challenging. Some approaches address people’s experiences of creativity. The present method measures creativity, across conditions, in the products that people make.

This research introduces
information-based ideation
(IBI), a paradigm for investigating open-ended tasks and activities in which users develop new ideas. IBI tasks span imagining, planning, and reflecting on a weekend, vacation, outfit, makeover, paper, internship, thesis, design, campaign, crisis response, career, or invention. What products do people create through engagement in IBI?
Curation
of digital media incorporates conceptualization, finding and choosing information objects, annotation, and synthesis. Through engagement in IBI tasks, people create curation products. This article formulates a quantitative methodology for evaluating IBI support tools, building on prior creative cognition research in engineering design to derive a battery of
ideation metrics of curation. Elemental ideation metrics
evaluate creativity within curated found objects.
Holistic ideation metrics
evaluate how a curation puts elements together.

IBI support environments are characterized by their underlying medium of curation. Curation media include lists, such as listicles, and grids, such as the boards of Pinterest.

An in-depth case study investigates
information composition
, an art-based medium representing a curation as a freeform visual semantic connected whole. We raise two creative cognition challenges for IBI. One challenge is overcoming fixation—for instance, when a person gets stuck in a counterproductive mental set. The other challenge is to bridge information visualization’s
synthesis gap
, by providing support for connecting findings. To address the challenges, we develop
mixed-initiative information composition
(MI
2
C), integrating human curation of information composition with automated agents of information retrieval and visualization.

We hypothesize that MI
2
C generates
provocative stimuli
that help users overcome fixation to become more creative on IBI tasks. We hypothesize that MI
2
C’s integration of curation and visualization bridges the synthesis gap to help users become more creative. To investigate these hypotheses, we apply ideation metrics of curation to interpret results from experiments with 44 and 49 participants.
Maximizing Quality of Coverage under Connectivity Constraints in Solar-Powered Active Wireless Sensor Networks
Authors: Gaudette Benjamin , Hanumaiah Vinay , Krunz Marwan , Vrudhula Sarma
Published: July 2014

Energy harvesting is a promising solution for reducing network maintenance and the overhead of replacing chemical batteries in sensor networks. In this article, problems related to controlling an active wireless sensor network comprised of nodes powered by both rechargeable batteries and solar energy are investigated. The objective of this control is to maximize the network's Quality of Coverage (QoC), defined as the minimum number of targets that can be covered by the network over a 24-hour period. Assuming a time-varying solar profile, the underlying problem is to optimally control the sensing range of each sensor so as to maximize the QoC. The problem is further constrained by requiring all active sensors to report any sensed data to a centralized base station, making connectivity a key factor in sensor management. Implicit in the solution is the allocation of solar energy during the day to sensing tasks and recharging of the battery so that a minimum coverage is guaranteed at all times. The problem turns out to be a nonlinear optimal control problem of high complexity. By exploiting the particular structure of the problem, we present a novel method for determining near-optimal sensing radii and routing paths as a series of quasiconvex (unimodal) optimization problems. The runtime of the proposed solution is 60X less than the standard optimal control method based on dynamic programming, while the worst-case error is less than 8%. The proposed method is scalable to large networks consisting of hundreds of sensors and targets. Several insights in the design of energy-harvesting networks are provided.
Towards the Temporally Perfect Virtual Button: Touch-Feedback Simultaneity and Perceived Quality in Mobile Touchscreen Press Interactions
Authors: Kaaresoja Topi , Brewster Stephen , Lantz Vuokko
Published: July 2014

Pressing a virtual button is still the major interaction method in touchscreen mobile phones. Although phones are becoming more and more powerful, operating system software is getting more and more complex, causing latency in interaction. We were interested in gaining insight into touch-feedback simultaneity and the effects of latency on the perceived quality of touchscreen buttons. In an experiment, we varied the latency between touch and feedback between 0 and 300 ms for tactile, audio, and visual feedback modalities. We modelled the proportion of simultaneity perception as a function of latency for each modality condition. We used a Gaussian model fitted with the maximum likelihood estimation method to the observations. These models showed that the point of subjective simultaneity (PSS) was 5ms for tactile, 19ms for audio, and 32ms for visual feedback. Our study included the scoring of perceived quality for all of the different latency conditions. The perceived quality dropped significantly between latency conditions 70 and 100 ms when the feedback modality was tactile or audio, and between 100 and 150 ms when the feedback modality was visual. When the latency was 300ms for all feedback modalities, the quality of the buttons was rated significantly lower than in all of the other latency conditions, suggesting that a long latency between a touch on the screen and feedback is problematic for users. Together with PSS and these quality ratings, a 75% threshold was established to define a guideline for the recommended latency range between touch and feedback. Our guideline suggests that tactile feedback latency should be between 5 and 50 ms, audio feedback latency between 20 and 70 ms, and visual feedback latency between 30 and 85 ms. Using these values will ensure that users will perceive the feedback as simultaneous with the finger's touch. These values also ensure that the users do not perceive reduced quality. These results will guide engineers and designers of touchscreen interactions by showing the trade-offs between latency and user preference and the effects that their choices might have on the quality of the interactions and feedback they design.
Discrete Event Execution with One-Sided and Two-Sided GVT Algorithms on 216,000 Processor Cores
Authors: Perumalla Kalyan S. , Park Alfred J. , Tipparaju Vinod
Published: July 2014

Global Virtual Time (GVT) computation is a key determinant of the efficiency and runtime dynamics of Parallel Discrete Event Simulations (PDES), especially on large-scale parallel platforms. Here, three execution modes of a generalized GVT computation algorithm are studied on high-performance parallel computing systems: (1) a synchronous GVT algorithm that affords ease of implementation, (2) an asynchronous GVT algorithm that is more complex to implement but can relieve blocking latencies, and (3) a variant of the asynchronous GVT algorithm to exploit one-sided communication in extant supercomputing platforms. Performance results are presented of implementations of these algorithms on up to 216,000 cores of a Cray XT5 system, exercised on a range of parameters: optimistic and conservative synchronization, fine- to medium-grained event computation, synthetic and nonsynthetic applications, and different lookahead values. Detailed PDES-specific runtime metrics are presented to further the understanding of tightly coupled discrete event dynamics on massively parallel platforms.
A Mapping-Scheduling Algorithm for Hardware Acceleration on Reconfigurable Platforms
Authors: Clemente Juan Antonio , Beretta Ivan , Rana Vincenzo , Atienza David , Sciuto Donatella
Published: July 2014

Reconfigurable platforms are a promising technology that offers an interesting trade-off between flexibility and performance, which many recent embedded system applications demand, especially in fields such as multimedia processing. These applications typically involve multiple ad-hoc tasks for hardware acceleration, which are usually represented using formalisms such as Data Flow Diagrams (DFDs), Data Flow Graphs (DFGs), Control and Data Flow Graphs (CDFGs) or Petri Nets. However, none of these models is able to capture at the same time the pipeline behavior between tasks (that therefore can coexist in order to minimize the application execution time), their communication patterns, and their data dependencies. This article proves that the knowledge of all this information can be effectively exploited to reduce the resource requirements and the timing performance of modern reconfigurable systems, where a set of hardware accelerators is used to support the computation. For this purpose, this article proposes a novel task representation model, named Temporal Constrained Data Flow Diagram (TCDFD), which includes all this information. This article also presents a mapping-scheduling algorithm that is able to take advantage of the new TCDFD model. It aims at minimizing the dynamic reconfiguration overhead while meeting the communication requirements among the tasks. Experimental results show that the presented approach achieves up to 75% of resources saving and up to 89% of reconfiguration overhead reduction with respect to other state-of-the-art techniques for reconfigurable platforms.
Applying user-centered design to research work
Authors: Scholtz Jean , Love Oriana , Pike William , Bruce Joseph , Kim Dee , McBain Arthur
Published: July 2014

Evaluation and usability as a practice area has diversified its approaches, broadened the spectrum of UX issues it addresses, methodological, and professional issues that arise in the field's continuing effort to contribute robust information about users to product planning and design. ---
David Siegel and Susan Dray, Editors
Big data and its technical challenges
Authors: Jagadish H. V. , Gehrke Johannes , Labrinidis Alexandros , Papakonstantinou Yannis , Patel Jignesh M. , Ramakrishnan Raghu , Shahabi Cyrus
Published: July 2014

Exploring the inherent technical challenges in realizing the potential of Big Data.
Pure Land
Authors: Kenderdine Sarah , Chan Leith K. Y. , Shaw Jeffrey
Published: July 2014

This article describes the design and implementation of the
Pure Land
projects, consisting of two visualization systems and their respective applications,
Pure Land: Inside the Mogao Grottoes at Dunhuang
[2012] and
Pure Land Augmented Reality Edition
[2012]. Each installation allows participants to engage in different ways with a full-scale augmented digital facsimile of Cave 220 from the UNESCO World Heritage site of the Mogao Grottoes, Gansu Province, northwestern China. This project is a collaboration between the Applied Laboratory for Interactive Visualization and Embodiment (ALiVE), City University of Hong Kong, and the Dunhuang Academy. In the
Pure Land
projects, the digital facsimiles of this cultural paragon have been transformed, providing formative personal experiences for museum visitors. The projects integrate high-resolution digital archeological datasets (photography and 3D architectural models) with immersive, interactive display systems. This work is of great importance because the treasuries of paintings and sculptures at Dunhuang are extremely vulnerable to human presence and, in the case of Cave 220, permanently closed to public visitors. Comprehensive digitization has become a primary method of preservation at the site. Both installations have been shown to the public at a variety of museums and galleries worldwide—to critical acclaim. The projects contribute to new strategies for rendering cultural content and heritage landscapes and suggest the future for embodied museography. Here, each project is described in detail, including innovations in interface technological application and user experience.
The Hybrid Artisans
Authors: Zoran Amit , Shilkrot Roy , Nanyakkara Suranga , Paradiso Joseph
Published: July 2014

We present an approach to combining digital fabrication and craft, demonstrating a hybrid interaction paradigm where human and machine work in synergy. The FreeD is a hand-held digital milling device, monitored by a computer while preserving the makers freedom to manipulate the work in many creative ways. Relying on a pre-designed 3D model, the computer gets into action only when the milling bit risks the objects integrity, preventing damage by slowing down the spindle speed, while the rest of the time it allows complete gestural freedom. We present the technology and explore several interaction methodologies for carving. In addition, we present a user study that reveals how synergetic cooperation between human and machine preserves the expressiveness of manual practice. This quality of the hybrid territory evolves into design personalization. We conclude on the creative potential of open-ended procedures within this hybrid interactive territory of manual smart tools and devices.
VTR 7.0
Authors: Luu Jason , Goeders Jeffrey , Wainberg Michael , Somerville Andrew , Yu Thien , Nasartschuk Konstantin , Nasr Miad , Wang Sen , Liu Tim , Ahmed Nooruddin , Kent Kenneth B. , Anderson Jason , Rose Jonathan , Betz Vaughn
Published: July 2014

Exploring architectures for large, modern FPGAs requires sophisticated software that can model and target hypothetical devices. Furthermore, research into new CAD algorithms often requires a complete and open source baseline CAD flow. This article describes recent advances in the open source Verilog-to-Routing (VTR) CAD flow that enable further research in these areas. VTR now supports designs with multiple clocks in both timing analysis and optimization. Hard adder/carry logic can be included in an architecture in various ways and significantly improves the performance of arithmetic circuits. The flow now models energy consumption, an increasingly important concern. The speed and quality of the packing algorithms have been significantly improved. VTR can now generate a netlist of the final post-routed circuit which enables detailed simulation of a design for a variety of purposes. We also release new FPGA architecture files and models that are much closer to modern commercial architectures, enabling more realistic experiments. Finally, we show that while this version of VTR supports new and complex features, it has a 1.5× compile time speed-up for simple architectures and a 6× speed-up for complex architectures compared to the previous release, with no degradation to timing or wire-length quality.
FPGA Implementation of a Special-Purpose VLIW Structure for Double-Precision Elementary Function
Authors: Lei Yuanwu , Guo Lei , Dou Yong , Ma Sheng , Xu Jinbo
Published: July 2014

In the current article, the capability and flexibility of field programmable gate-arrays (FPGAs) to implement IEEE-754 double-precision floating-point elementary functions are explored. To perform various elementary functions on the unified hardware efficiently, we propose a special-purpose very long instruction word (VLIW) processor, called DP_VELP. This processor is equipped with multiple basic units, and its performance is improved through an explicitly parallel technique. Pipelined evaluation of polynomial approximation with Estrin's scheme is proposed, by scheduling basic components in an optimal order to avoid data hazard stalls and achieve minimal latency. The custom VLIW processor can achieve high scalability. Under the control of specific VLIW instructions, the basic units are combined into special-purpose hardware for elementary functions. Common elementary functions are presented as examples to illustrate the design of elementary function in DP_VELP in detail. Minimax approximation scheme is used to reduce degree of polynomial. Compromise between the size of lookup table and the latency is discussed, and the internal precision is carefully planned to guarantee accuracy of the result. Finally, we create a prototype of the DP_VELP unit and an FPGA accelerator based on the DP_VELP unit on a Xilinx XC6VLX760 FPGA chip to implement the SGP4/SDP4 application.

Compared with previous researches, the proposed design can achieve low latency with a reasonable amount of resources and evaluate a variety of elementary functions with the unified hardware to satisfy the demands in scientific applications. Experimental results show that the proposed design guarantees more than 99% of correct rounding. Moreover, the SGP4/SDP4 accelerator, which is equipped with 39 DP_VELP units and runs at 200 MHz, outperforms the parallel software approach with hyper-thread technology on an Intel Xeon Quad E5620 CPU at 2.40 GHz by a factor of 7X.
Mobile Sensor Networks
Authors: Wang You-Chiun
Published: July 2014

Wireless sensor networks (WSNs) provide a convenient way to monitor the physical environment. They consist of a large number of sensors that have sensing, computing, and communication abilities. In the past, sensors were considered as static, but the network functionality would degrade when some sensors were broken. Today, the emerging hardware techniques have promoted the development of mobile sensors. Introducing mobility to sensors not only improves their capability but also gives them flexibility to deal with node failure. The article studies the research progress of mobile sensor networks, which embraces both system hardware and dispatch software. For system hardware, we review two popular types of mobile sensor platforms. One is to integrate mobile robots with sensors, whereas the other is to use existing conveyances to carry sensors. Dispatch software includes two topics. We first address how to solve different coverage problems by using a purely mobile WSN and then investigate how to dispatch mobile sensors in a hybrid WSN to perform various missions including data collection, faulty recovery, and event analysis. A discussion about research challenges in mobile sensor networks is also presented in the article.
Toward a pedagogy of ethical practice
Authors: Huff Chuck , Furchert Almut
Published: July 2014

Teaching computing ethics in a manner that allows students to address both abstract ethical knowledge and actual ethical practice.
Demo hour
Authors: Charland Caleb , Dörfelt Matthias , Echelman Janet , Koblin Aaron , Song Miao , Mokhov Serguei A. , Grogono Peter
Published: July 2014

Demo Hour highlights new prototypes and projects that exemplify innovation and novel forms of interaction. Audrey Desjardins, Editor
Social awareness in HCI
Authors: Baranauskas M. Cecília C.
Published: July 2014

In this forum we celebrate research that helps to successfully bring the benefits of computing technologies to children, older adults, people with disabilities, and other populations that are often ignored in the design of mass-marketed products. ---
Juan Pablo Hourcade, Editor
Finding more than one worm in the apple
Authors: Bland Mike
Published: July 2014

If you see something, say something.