bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimates of the temporal and spatial variability of ocean sound speed on the New Jersey shelf
Authors: Ballard Megan S. , Frisk George V. , Becker Kyle M.
Published: June 2014

Estimates of the spatial and temporal variability of ocean sound speed on the New Jersey shelf were obtained using acoustic signals measured by a set of freely drifting buoys. The range- and time-dependent inversion problem is computationally intensive and a linearized perturbative algorithm was applied to obtain results in an efficient manner. The inversion algorithm uses estimates of modal travel time to determine sound speed as a function of range and depth. In order to handle the high volume of data associated with the acoustic sensing network, the modal travel time estimation process was automated using an adaptive time-frequency signal processing method known as time-warping. Time-warping is a model-based transform that converts the frequency-dependent modal arrivals to monotones in the warped domain where they can be easily filtered. The data analyzed in this paper were collected on 16 March 2011 on the New Jersey shelf when the ocean was relatively well-mixed. While the observed sound-speed variations are small, both spatial and temporal trends are observed in the results. Furthermore, the estimated sound-speed profiles show good agreement with temporally and spatially collocated measurements.
Particle velocity gradient based acoustic mode beamforming for short linear vector sensor arrays
Authors: Gur Berke
Published: June 2014

In this paper, a subtractive beamforming algorithm for short linear arrays of two-dimensional particle velocity sensors is described. The proposed method extracts the highly directional acoustic modes from the spatial gradients of the particle velocity field measured at closely spaced sensors along the array. The number of sensors in the array limits the highest order of modes that can be extracted. Theoretical analysis and numerical simulations indicate that the acoustic mode beamformer achieves directivity comparable to the maximum directivity that can be obtained with differential microphone arrays of equivalent aperture. When compared to conventional delay-and-sum beamformers for pressure sensor arrays, the proposed method achieves comparable directivity with 70%–85% shorter apertures. Moreover, the proposed method has additional capabilities such as high front–back (port–starboard) discrimination, frequency and steer direction independent response, and robustness to correlated ambient noise. Small inter-sensor spacing that results in very compact apertures makes the proposed beamformer suitable for space constrained applications such as hearing aids and short towed arrays for autonomous underwater platforms.
Real and causal hysteresis elements
Authors: Parker Kevin J.
Published: June 2014

Hysteresis is a phenomenon that has been observed across many different materials and situations. Under small-amplitude cyclical motion, classical hysteresis designates a constant loss per cycle over a wide range of frequencies. This is also consistent with an increase in losses or attenuation with frequency that is strictly proportional to the first power of frequency. Unfortunately, the classical (and simple) frequency domain description of hysteresis does not result in a real and causal impulse response, and therefore is not useful for predicting laboratory results. This problem has led to many errors as well as other more fruitful approaches over the years. The frequency domain requirements for hysteresis are re-examined and it is demonstrated that there is a family of solutions that provide real and causal impulse responses over some extended frequency range. The family is conveniently divided into highpass, lowpass, and bandpass causal systems. These are populated by closed form analytical solutions which can be applied to the prediction of motion and waves in hysteretic materials and systems.
Markov-chain Monte Carlo identification of favorable design choices with application to anechoic coatings
Authors: Ivansson Sven M.
Published: June 2014

Global optimization methods can be used to numerically determine optimal design parameters for an object. However, this does not by itself give a good appreciation of other parameter choices that may be almost as good and even preferable from other points of view. In the present paper, Markov-chain Monte Carlo methods are used to go beyond the optimal solution and create an ensemble of object models in parameter space that covers a set of favorable models uniformly. In direct analogy with applications to Bayesian inversion with determination of an unknown posterior probability density, projections of the model ensemble onto parameter axes and planes are used to exhibit parameter sensitivities and dependencies. Design of anechoic rubber coatings, with cylinder cavities having axes in a lateral direction, is considered as a particular application. The anechoic effect is evaluated by the efficient layer-multiple-scattering method, which is extended to handle cylinder scatterers of noncircular cross sections and mixed types. As anticipated by computed scattering and absorption cross sections for an isolated cavity, the favorable coatings have oblate cavity cross-section shapes, which is useful to achieve good low-frequency reflection reduction with a thin coating.
Hold Your Breath or the Catfish Will Find You
Authors: Vignieri Sacha N.
Published: June 2014

Japanese sea catfish whiskers help to locate hidden worms by sensing pH increases associated with respiration.
Emerging from the Shade into the Light
Authors: Hines Pamela J.
Published: June 2014

Phytochrome and its partner transcription factor go to their doom together in response to a change in light quality.
Genes, Synapses, and Hallucinations
Authors: Stern Peter
Published: June 2014

In mice, dopamine D2 receptor up-regulation in the thalamus is responsible for auditory hallucinations.
GlyR Gets Inflamed
Authors: Berndt Jason D.
Published: June 2014

Inflammatory cytokines promote long-term potentiation of glycine receptors.
Metabolism OutFOXes Circadian Rhythm
Authors: VanHook Annalisa M.
Published: June 2014

The transcription factor FOXO3 promotes the expression of
Clock
and links insulin signaling to regulation of circadian rhythm in the liver.
Centrosomes Coordinate Cancer Invasion
Authors: Ferrarelli Leslie K.
Published: June 2014

Targeting microtubule nucleation induced by centrosome amplification may prevent invasive progression of tumors.
Leishmanicidal Activities of Novel Synthetic Furoxan and Benzofuroxan Derivatives
Authors: Dutra Luiz Antônio , de Almeida Letícia , Passalacqua Thais G. , Reis Juliana Santana , Torres Fabio A. E. , Martinez Isabel , Peccinini Rosangela Gonçalves , Chin Chung Man , Chegaev Konstantin , Guglielmo Stefano , Fruttero Roberta , Graminha Marcia A. S. , dos Santos Jean Leandro
Published: June 2014

A novel series of furoxan (1,2,5-oxadiazole 2-oxide) (compounds 3, 4a and -b, 13a and -b, and 14a to -f) and benzofuroxan (benzo[c][1,2,5]oxadiazole 1-oxide) (compounds 7 and 8a to -c) derivatives were synthesized, characterized, and evaluated for
in vitro
activity against promastigote and intracellular amastigote forms of
Leishmania amazonensis
. The furoxan derivatives exhibited the ability to generate nitric oxide at different levels (7.8% to 27.4%). The benzofuroxan derivative 8a was able to increase nitrite production in medium supernatant from murine macrophages infected with
L. amazonensis
at 0.75 mM after 48 h. Furoxan and benzofuroxan derivatives showed remarkable leishmanicidal activity against both promastigote and intracellular amastigote forms. Compounds 8a, 14a and -b, and 14d exerted selective leishmanicidal activities superior to those of amphotericin B and pentamidine.
In vitro
studies at pH 5.4 reveal that compound 8a is stable until 8 h and that compound 14a behaves as a prodrug, releasing the active aldehyde 13a. These compounds have emerged as promising novel drug candidates for the treatment of leishmaniasis.
Downregulation of Cellular c-Jun N-Terminal Protein Kinase and NF-κB Activation by Berberine May Result in Inhibition of Herpes Simplex Virus Replication
Authors: Song Siwei , Qiu Min , Chu Ying , Chen Deyan , Wang Xiaohui , Su Airong , Wu Zhiwei
Published: June 2014

Berberine is a quaternary ammonium salt from the protoberberine group of isoquinoline alkaloids. Some reports show that berberine exhibits anti-inflammatory, antitumor, and antiviral properties by modulating multiple cellular signaling pathways, including p53, nuclear factor κB (NF-κB), and mitogen-activated protein kinase. In the present study, we investigated the antiviral effect of berberine against herpes simplex virus (HSV) infection. Current antiherpes medicines such as acyclovir can lessen the recurring activation when used early at infection but are unable to prevent or cure infections where treatment has selected for resistant mutants. In searching for new antiviral agents against herpesvirus infection, we found that berberine reduced viral RNA transcription, protein synthesis, and virus titers in a dose-dependent manner. To elucidate the mechanism of its antiviral activity, the effect of berberine on the individual steps of viral replication cycle of HSV was investigated via time-of-drug addition assay. We found that berberine acted at the early stage of HSV replication cycle, between viral attachment/entry and genomic DNA replication, probably at the immediate-early gene expression stage. We further demonstrated that berberine significantly reduced HSV-induced NF-κB activation, as well as IκB-α degradation and p65 nuclear translocation. Moreover, we found that berberine also depressed HSV-induced c-Jun N-terminal kinase (JNK) phosphorylation but had little effect on p38 phosphorylation. Our results suggest that the berberine inhibition of HSV infection may be mediated through modulating cellular JNK and NF-κB pathways.
Antibiotics for Treatment of Clostridium difficile Infection in Hospitalized Patients with Inflammatory Bowel Disease
Authors: Horton Henry A. , Dezfoli Seper , Berel Dror , Hirsch Julianna , Ippoliti Andrew , McGovern Dermot , Kaur Manreet , Shih David , Dubinsky Marla , Targan Stephan R. , Fleshner Phillip , Vasiliauskas Eric A. , Grein Jonathan , Murthy Rekha , Melmed Gil Y.
Published: June 2014

Patients with inflammatory bowel disease (IBD), namely ulcerative colitis (UC) and Crohn's disease (CD), have worse outcomes with
Clostridium difficile
infection (CDI), including increased readmissions, colectomy, and death. Oral vancomycin is recommended for the treatment of severe CDI, while metronidazole is the standard of care for nonsevere infection. We aimed to assess treatment outcomes of CDI in IBD. We conducted a retrospective observational study of inpatients with CDI and IBD from January 2006 through December 2010. CDI severity was assessed using published criteria. Outcomes included readmission for CDI within 30 days and 12 weeks, length of stay, colectomy, and death. A total of 114 patients met inclusion criteria (UC, 62; CD, 52). Thirty-day readmissions were more common among UC than CD patients (24.2% versus 9.6%;
P
= 0.04). Same-admission colectomy occurred in 27.4% of UC patients and 0% of CD patients (
P
< 0.01). Severe CDI was more common among UC than CD patients (32.2% versus 19.4%;
P
= 0.12) but not statistically significant. Two patients died from CDI-associated complications (UC, 1; CD, 1). Patients with UC and nonsevere CDI had fewer readmissions and shorter lengths of stay when treated with a vancomycin-containing regimen compared to those treated with metronidazole (30-day readmissions, 31.0% versus 0% [
P
= 0.04]; length of stay, 13.62 days versus 6.38 days [
P
= 0.02]). Patients with UC and nonsevere CDI have fewer readmissions and shorter lengths of stay when treated with a vancomycin-containing regimen relative to those treated with metronidazole alone. Patients with ulcerative colitis and CDI should be treated with vancomycin.
Switch-Loop Flexibility Affects Transport of Large Drugs by the Promiscuous AcrB Multidrug Efflux Transporter
Authors: Cha Hi-jea , Müller Reinke T. , Pos Klaas M.
Published: June 2014

Multidrug efflux transporters recognize a variety of structurally unrelated compounds for which the molecular basis is poorly understood. For the
r
esistance
n
odulation and cell
d
ivision (RND) inner membrane component AcrB of the AcrAB-TolC multidrug efflux system from
Escherichia coli
, drug binding occurs at the access and deep binding pockets. These two binding areas are separated by an 11-amino-acid-residue-containing switch loop whose conformational flexibility is speculated to be essential for drug binding and transport. A G616N substitution in the switch loop has a distinct and local effect on the orientation of the loop and on the ability to transport larger drugs. Here, we report a distinct phenotypical pattern of drug recognition and transport for the G616N variant, indicating that drug substrates with minimal projection areas of >70 Å
2
are less well transported than other substrates.
Differential Protection from Tobramycin by Extracellular Polymeric Substances from Acinetobacter baumannii and Staphylococcus aureus Biofilms
Authors: Davenport Emily K. , Call Douglas R. , Beyenal Haluk
Published: June 2014

We investigated biofilms of two pathogens,
Acinetobacter baumannii
and
Staphylococcus aureus
, to characterize mechanisms by which the extracellular polymeric substance (EPS) found in biofilms can protect bacteria against tobramycin exposure. To do so, it is critical to study EPS-antibiotic interactions in a homogeneous environment without mass transfer limitations. Consequently, we developed a method to grow biofilms, harvest EPS, and then augment planktonic cultures with isolated EPS and tobramycin. We demonstrated that planktonic cultures respond differently to being treated with different types of EPS (
A. baumannii
versus
S. aureus
) in the presence of tobramycin. By harvesting EPS from the biofilms, we found that
A. baumannii
EPS acts as a “universal protector” by inhibiting tobramycin activity against bacterial cells regardless of species;
S. aureus
EPS did not show any protective ability in cell cultures. Adding Mg
2+
or Ca
2+
reduced the protective effect of
A. baumannii
EPS. Finally, when we selectively digested the proteins or DNA of the EPS, we found that the protective ability did not change, suggesting that neither has a significant role in protection. To the best of our knowledge, this is the first study that demonstrates how EPS protects pathogens against antibiotics in a homogeneous system without mass transfer limitations. Our results suggest that EPS protects biofilm communities, in part, by adsorbing antibiotics near the surface. This may limit antibiotic diffusion to the bottom of the biofilms but is not likely to be the only mechanism of protection.
Discovery of Gene Cluster for Mycosporine-Like Amino Acid Biosynthesis from Actinomycetales Microorganisms and Production of a Novel Mycosporine-Like Amino Acid by Heterologous Expression
Authors: Miyamoto Kiyoko T. , Komatsu Mamoru , Ikeda Haruo
Published: June 2014

Mycosporines and mycosporine-like amino acids (MAAs), including shinorine (mycosporine-glycine-serine) and porphyra-334 (mycosporine-glycine-threonine), are UV-absorbing compounds produced by cyanobacteria, fungi, and marine micro- and macroalgae. These MAAs have the ability to protect these organisms from damage by environmental UV radiation. Although no reports have described the production of MAAs and the corresponding genes involved in MAA biosynthesis from Gram-positive bacteria to date, genome mining of the Gram-positive bacterial database revealed that two microorganisms belonging to the order
Actinomycetales
,
Actinosynnema mirum
DSM 43827 and
Pseudonocardia
sp. strain P1, possess a gene cluster homologous to the biosynthetic gene clusters identified from cyanobacteria. When the two strains were grown in liquid culture,
Pseudonocardia
sp. accumulated a very small amount of MAA-like compound in a medium-dependent manner, whereas
A. mirum
did not produce MAAs under any culture conditions, indicating that the biosynthetic gene cluster of
A. mirum
was in a cryptic state in this microorganism. In order to characterize these biosynthetic gene clusters, each biosynthetic gene cluster was heterologously expressed in an engineered host,
Streptomyces avermitilis
SUKA22. Since the resultant transformants carrying the entire biosynthetic gene cluster controlled by an alternative promoter produced mainly shinorine, this is the first confirmation of a biosynthetic gene cluster for MAA from Gram-positive bacteria. Furthermore,
S. avermitilis
SUKA22 transformants carrying the biosynthetic gene cluster for MAA of
A. mirum
accumulated not only shinorine and porphyra-334 but also a novel MAA. Structure elucidation revealed that the novel MAA is mycosporine-glycine-alanine, which substitutes
l
-alanine for the
l
-serine of shinorine.
ε-Poly-
l
-Lysine Peptide Chain Length Regulated by the Linkers Connecting the Transmembrane Domains of ε-Poly-
l
-Lysine Synthetase
Authors: Hamano Yoshimitsu , Kito Naoko , Kita Akihiro , Imokawa Yuuki , Yamanaka Kazuya , Maruyama Chitose , Katano Hajime
Published: June 2014

ε-Poly-
l
-lysine (ε-PL), consisting of 25 to 35
l
-lysine residues with linkages between the α-carboxyl groups and ε-amino groups, is produced by
Streptomyces albulus
NBRC14147. ε-PL synthetase (Pls) is a membrane protein with six transmembrane domains (TM1 to TM6) as well as both an adenylation domain and a thiolation domain, characteristic of the nonribosomal peptide synthetases. Pls directly generates ε-PL chain length diversity (25- to 35-mer), but the processes that control the chain length of ε-PL during the polymerization reaction are still not fully understood. Here, we report on the identification of Pls amino acid residues involved in the regulation of the ε-PL chain length. From approximately 12,000 variants generated by random mutagenesis, we found 8 Pls variants that produced shorter chains of ε-PL. These variants have one or more mutations in two linker regions connecting the TM1 and TM2 domains and the TM3 and TM4 domains. In the Pls catalytic mechanism, the growing chain of ε-PL is not tethered to the enzyme, implying that the enzyme must hold the growing chain until the polymerization reaction is complete. Our findings reveal that the linker regions are important contributors to grasp the growing chain of ε-PL.
Knockout of Extracytoplasmic Function Sigma Factor ECF-10 Affects Stress Resistance and Biofilm Formation in Pseudomonas putida KT2440
Authors: Tettmann Beatrix , Dötsch Andreas , Armant Olivier , Fjell Christopher D. , Overhage Joerg
Published: June 2014

Pseudomonas putida
is a Gram-negative soil bacterium which is well-known for its versatile lifestyle, controlled by a large repertoire of transcriptional regulators. Besides one- and two-component regulatory systems, the genome of
P. putida
reveals 19 extracytoplasmic function (ECF) sigma factors involved in the adaptation to changing environmental conditions. In this study, we demonstrate that knockout of extracytoplasmic function sigma factor ECF-10, encoded by open reading frame PP4553, resulted in 2- to 4-fold increased antibiotic resistance to quinolone, β-lactam, sulfonamide, and chloramphenicol antibiotics. In addition, the ECF-10 mutant exhibited enhanced formation of biofilms after 24 h of incubation. Transcriptome analysis using Illumina sequencing technology resulted in the detection of 12 genes differentially expressed (>2-fold) in the ECF-10 knockout mutant strain compared to their levels of expression in wild-type cells. Among the upregulated genes were
ttgA
,
ttgB
, and
ttgC
, which code for the major multidrug efflux pump TtgABC in
P. putida
KT2440. Investigation of an ECF-10 and
ttgA
double-knockout strain and a
ttgABC
-overexpressing strain demonstrated the involvement of efflux pump TtgABC in the stress resistance and biofilm formation phenotypes of the ECF-10 mutant strain, indicating a new role for this efflux pump beyond simple antibiotic resistance in
P. putida
KT2440.
Platelet Endothelial Cell Adhesion Molecule-1, a Putative Receptor for the Adhesion of Streptococcus pneumoniae to the Vascular Endothelium of the Blood-Brain Barrier
Authors: Iovino Federico , Molema Grietje , Bijlsma Jetta J. E.
Published: June 2014

The Gram-positive bacterium
Streptococcus pneumoniae
is the main causative agent of bacterial meningitis.
S. pneumoniae
is thought to invade the central nervous system via the bloodstream by crossing the vascular endothelium of the blood-brain barrier. The exact mechanism by which pneumococci cross endothelial cell barriers before meningitis develops is unknown. Here, we investigated the role of PECAM-1/CD31, one of the major endothelial cell adhesion molecules, in
S. pneumoniae
adhesion to vascular endothelium of the blood-brain barrier. Mice were intravenously infected with pneumococci and sacrificed at various time points to represent stages preceding meningitis. Immunofluorescent analysis of brain tissue of infected mice showed that pneumococci colocalized with PECAM-1. In human brain microvascular endothelial cells (HBMEC) incubated with
S. pneumoniae
, we observed a clear colocalization between PECAM-1 and pneumococci. Blocking of PECAM-1 reduced the adhesion of
S. pneumoniae
to endothelial cells
in vitro
, implying that PECAM-1 is involved in pneumococcal adhesion to the cells. Furthermore, using endothelial cell protein lysates, we demonstrated that
S. pneumoniae
physically binds to PECAM-1. Moreover, both
in vitro
and
in vivo
PECAM-1 colocalizes with the
S. pneumoniae
adhesion receptor pIgR. Lastly, immunoprecipitation experiments revealed that PECAM-1 can physically interact with pIgR. In summary, we show for the first time that blood-borne
S. pneumoniae
colocalizes with PECAM-1 expressed by brain microvascular endothelium and that, in addition, they colocalize with pIgR. We hypothesize that this interaction plays a role in pneumococcal binding to the blood-brain barrier vasculature prior to invasion into the brain.
Benzylidene Acylhydrazides Inhibit Chlamydial Growth in a Type III Secretion- and Iron Chelation-Independent Manner
Authors: Bao Xiaofeng , Gylfe Åsa , Sturdevant Gail L. , Gong Zheng , Xu Shuang , Caldwell Harlan D. , Elofsson Mikael , Fan Huizhou
Published: June 2014

Chlamydiae are widespread Gram-negative pathogens of humans and animals. Salicylidene acylhydrazides, developed as inhibitors of type III secretion system (T3SS) in
Yersinia
spp., have an inhibitory effect on chlamydial infection. However, these inhibitors also have the capacity to chelate iron, and it is possible that their antichlamydial effects are caused by iron starvation. Therefore, we have explored the modification of salicylidene acylhydrazides with the goal to uncouple the antichlamydial effect from iron starvation. We discovered that benzylidene acylhydrazides, which cannot chelate iron, inhibit chlamydial growth. Biochemical and genetic analyses suggest that the derivative compounds inhibit chlamydiae through a T3SS-independent mechanism. Four single nucleotide polymorphisms were identified in a
Chlamydia muridarum
variant resistant to benzylidene acylhydrazides, but it may be necessary to segregate the mutations to differentiate their roles in the resistance phenotype. Benzylidene acylhydrazides are well tolerated by host cells and probiotic vaginal
Lactobacillus
species and are therefore of potential therapeutic value.
Fifty Years after the Replicon Hypothesis: Cell-Specific Master Regulators as New Players in Chromosome Replication Control
Authors: Wolański Marcin , Jakimowicz Dagmara , Zakrzewska-Czerwińska Jolanta
Published: June 2014

Numerous free-living bacteria undergo complex differentiation in response to unfavorable environmental conditions or as part of their natural cell cycle. Developmental programs require the
de novo
expression of several sets of genes responsible for morphological, physiological, and metabolic changes, such as spore/endospore formation, the generation of flagella, and the synthesis of antibiotics. Notably, the frequency of chromosomal replication initiation events must also be adjusted with respect to the developmental stage in order to ensure that each nascent cell receives a single copy of the chromosomal DNA. In this review, we focus on the master transcriptional factors, Spo0A, CtrA, and AdpA, which coordinate developmental program and which were recently demonstrated to control chromosome replication. We summarize the current state of knowledge on the role of these developmental regulators in synchronizing the replication with cell differentiation in
Bacillus subtilis
,
Caulobacter crescentus
, and
Streptomyces coelicolor
, respectively.
Identification of Three Noncontiguous Regions on Bacillus anthracis Plasmid pXO1 That Are Important for Its Maintenance
Authors: Pomerantsev Andrei P. , Chang Zanetta , Rappole Catherine , Leppla Stephen H.
Published: June 2014

Bacillus anthracis
pXO1 minireplicon (MR) plasmid consisting of open reading frames (ORFs) GBAA_pXO1_0020 to GBAA_pXO1_0023 is not stably maintained in
B. anthracis
, whereas the full-size parent pXO1 plasmid (having 181,677 bp and 217 ORFs) is extremely stable under the same growth conditions. Two genetic tools developed for DNA manipulation in
B. anthracis
(Cre-
loxP
and Flp-
FRT
systems) were used to identify pXO1 regions important for plasmid stability. We localized a large segment of pXO1 that enables stable plasmid maintenance during vegetative growth. Further genetic analysis identified three genes that are necessary for pXO1 maintenance:
amsP
(GBAA_pXO1_0069),
minP
(GBAA_pXO1_0082), and
sojP
(GBAA_pXO1_0084). Analysis of conserved domains in the corresponding proteins indicated that only AmsP (activator of maintenance system of pXO1) is predicted to bind DNA, due to its strong helix-turn-helix domain. Two conserved domains were found in the MinP protein (Min protein from pXO1): an N-terminal domain having some similarity to the
B. anthracis
septum site-determining protein MinD and a C-terminal domain that resembles a baculovirus single-stranded-DNA-binding protein. The SojP protein (Soj from pXO1) contains putative Walker box motifs and belongs to the ParA family of ATPases. No sequences encoding other components of type I plasmid partition systems, namely,
cis
-acting centromere
parS
and its binding ParB protein, were identified within the pXO1 genome. A model describing the role of the MinP protein in pXO1 distribution between daughter cells is proposed.
TraK and TraB Are Conserved Outer Membrane Proteins of the Neisseria gonorrhoeae Type IV Secretion System and Are Expressed at Low Levels in Wild-Type Cells
Authors: Ramsey Meghan E. , Hackett Kathleen T. , Bender Tobias , Kotha Chaitra , van der Does Chris , Dillard Joseph P.
Published: June 2014

Neisseria gonorrhoeae
uses a type IV secretion system (T4SS) to secrete chromosomal DNA into the medium, and this DNA is effective in transforming other gonococci via natural transformation. In addition, the T4SS is important in the initial stages of biofilm development and mediates intracellular iron uptake in the absence of TonB. To better understand the mechanism of type IV secretion in
N. gonorrhoeae
, we examined the expression levels and localization of two predicted T4SS outer membrane proteins, TraK and TraB, in the wild-type strain as well as in overexpression strains and in a strain lacking all of the T4SS proteins. Despite very low sequence similarity to known homologues, TraB (VirB10 homolog) and TraK (VirB9 homolog) localized similarly to related proteins in other systems. Additionally, we found that TraV (a VirB7 homolog) interacts with TraK, as in other T4SSs. However, unlike in other systems, neither TraK nor TraB required the presence of other T4SS components for proper localization. Unlike other gonococcal T4SS proteins we have investigated, protein levels of the outer membrane proteins TraK and TraB were extremely low in wild-type cells and were undetectable by Western blotting unless overexpressed or tagged with a FLAG3 triple-epitope tag. Localization of TraK-FLAG3 in otherwise wild-type cells using immunogold electron microscopy of thin sections revealed a single gold particle on some cells. These results suggest that the gonococcal T4SS may be present in single copy per cell and that small amounts of T4SS proteins TraK and TraB are sufficient for DNA secretion.
Persistence of hepatitis B surface antigen in blood in a chronic haemodialysis patient following vaccination booster
Authors: Calisti Giorgio , Herman Omar , Powley Michelle , Haque Tanzina
Published: June 2014

Patients receiving haemodialysis are at an increased risk of hepatitis B infection; regular screening for incident infection and vaccination of susceptible individuals is recommended. Haemodialysis patients often require repeated high-dose hepatitis B vaccination boosters because of impaired response. Since the hepatitis B surface antigen is used as an immunogenic agent for vaccination and as a marker of hepatitis B infection, it has occasionally been detected in the blood shortly after vaccine administration and can be mistaken for a new infection. These transient results, however, are unlikely to persist for longer than 14 days after vaccination. We report the case of a haemodialysis patient who tested weakly positive for hepatitis B surface antigen 52 days after a vaccine booster. This is the longest vaccine-induced antigenaemia described in the literature and indicates that vaccination can cause weakly positive hepatitis B surface antigen results for longer than previously reported.
Treating enuresis in a patient with ADHD: application of a novel behavioural modification therapy
Authors: Tajima-Pozo Kazuhiro , Ruiz-Manrique Gonzalo , Montañes Francisco
Published: June 2014

We report the case of a 6-year-old patient diagnosed with attention-deficit hyperactivity disorder (ADHD) and comorbid enuresis disorder, who was treated with methylphenidate for the past 3 months and a novel behavioural modification therapy by using an application called ‘Enuresis Trainer’. This therapeutic application is basically an interactive ‘Bedwetting Calendar’, based on traditional cognitive behavioural modification therapies and positive reinforcement systems. Enuresis is defined as the failure of voluntary control of the urethral sphincter. The prevalence of enuresis is 15–20% in the child population; however, children with ADHD had a 2.7 times higher incidence of nocturnal enuresis. Bedwetting is a common cause of isolation in children as well as loss of self-esteem and other psychological distress for the child and the family.
Unusual panuveitis in a child: toxocariasis associated with ocular myiasis
Authors: Marques André , Rodrigues António , Belo Silvana , Guedes Marta Esteves
Published: June 2014

Most panuveitis in children are caused by infectious agents. A detailed clinical history and clinical examination are helpful in the diagnosis, but specific techniques are sometimes required to identify the causing specimen. We report the first published case of panuveitis in a child caused by simultaneous ocular infection byToxocara canisand a fly larva and the innovative use of immunodiffusion technique in the vitreous for the diagnosis.
Successful treatment ofSalmonellaaortitis with endovascular aortic repair and antibiotic therapy
Authors: Parekh Parth J , Shams Rouzbeh , Challapallisri Vaishnavi , Marik Paul E
Published: June 2014

We report a case of a 77-year-old Asian man with a history significant for type II diabetes mellitus and chronic kidney disease who presented with abdominal pain, nausea, vomiting and a 20-pound weight loss of 3 weeks’ duration. Further evaluation revealed an infected mycotic aneurysm and distal abdominal aortitis as a result ofSalmonella. This case demonstrates an interesting case of aortitis and a successful therapeutic approach.
Psychiatric disorders following fetal death: a population-based cohort study
Authors: Munk-Olsen Trine , Bech Bodil Hammer , Vestergaard Mogens , Li Jiong , Olsen Jørn , Laursen Thomas Munk
Published: June 2014

Objectives

Women have increased risks of severe mental disorders after childbirth and death of a child, but it remains unclear whether this association also applies to fetal loss and, if so, to which extent. We studied the risk of any inpatient or outpatient psychiatric treatment during the time period from 12 months before to 12 months after fetal death.

Design

Cohort study using Danish population-based registers.

Setting

Denmark.

Participants

A total of 1 112 831 women born in Denmark from 1960 to 1995 were included. In total, 87 687cases of fetal death (International Classification of Disease-10 codes for spontaneous abortion or stillbirth) were recorded between 1996 and 2010.

Primary and secondary outcome measures

The main outcome measures were incidence rate ratios (risk of first psychiatric inpatient or outpatient treatment).

Results

A total of 1379 women had at least one psychiatric episode during follow-up from the year before fetal death to the year after. Within the first few months after the loss, women had an increased risk of psychiatric contact, IRR: 1.51 (95% CI 1.15 to 1.99). In comparison, no increased risk of psychiatric contact was found for the period before fetal death. The risk of experiencing a psychiatric episode was highest for women with a loss occurring after 20 weeks of gestation (12 month probability: 1.95%, 95% CI 1.50 to 2.39).

Conclusions

Fetal death was associated with a transient increased risk of experiencing a first-time episode of a psychiatric disorder, primarily adjustment disorders. The risk of psychiatric episodes tended to increase with increasing gestational age at the time of the loss.
Incidence, characteristics and risk factors for household and neighbourhood injury among young children in semiurban Ghana: a population-based household survey
Authors: Gyedu A , Nakua E K , Otupiri E , Mock C , Donkor P , Ebel B
Published: June 2014

Background

There are few population-based studies on household child injury in African countries.

Objectives

To determine the incidence, characteristics and risk factors of household and neighbourhood injury among children in semiurban communities in Kumasi, Ghana.

Methods

We conducted a cross-sectional population-weighted survey of 200 randomly selected caregivers of children under 18, representing 6801 households. Caregivers were interviewed about moderate to severe childhood injuries occurring within the past 6 months, for which the child staying home from school or activity, and/or required medical care. Multivariable logistic regression was used to identify factors associated with injury risk.

Results

Annual injury incidence was 593.5 injuries per 1000 children. Common causes of injury were falls (315.7 injuries per 1000 children), followed by cuts/lacerations and burns. Most injuries (93.8%) were of moderate severity. Children whose caregivers were hourly workers (AOR=1.97; 95% CI 1.06 to 3.68) had increased odds of sustaining an injury compared to those of unemployed caregivers. Girls had decreased odds of injury (AOR=0.59; 95% CI 0.39 to 0.91). Cooking outdoors (AOR=0.45; 95% CI 0.27 to 0.76) and presence of cabinet/cupboards (AOR=0.41; 95% CI 0.24 to 0.70) in the house were protective. Among children under 5 years of age, living in uncompleted accommodation was associated with higher odds of injury compared with living in a rented single room (AOR=3.67; 95% CI 1.17 to 11.48).

Conclusions

The incidence of household and neighbourhood child injury is high in semiurban Kumasi. We identified several novel injury risk factors (hourly work, younger children) and protective factors (cooking outdoors, presence of cabinet/cupboards). These data may identify priorities for household injury prevention.
Pregnancy outcomes among African–American patients with systemic lupus erythematosus compared with controls
Authors: Barnado April , Wheless Lee , Meyer Anna K , Gilkeson Gary S , Kamen Diane L
Published: June 2014

Objective

In a study of Gullah African–Americans, we compared pregnancy outcomes before and after systemic lupus erythematosus (SLE) diagnosis to controls to test whether there is a predisease state that negativelyaffects pregnancy outcomes.

Design

Cases and controls reporting at least one pregnancy were included. Controls were all Gullah African-American females. We collected demographic, socioeconomic and pregnancy data. We modelled pregnancy outcome associations with case status using multiple logistic regression to calculate ORs.

Results

After adjustment for age, years of education, medical coverage and pregnancy number, compared with controls, cases were more likely to have any adverse outcome (OR 2.35, 95% CI 1.78 to 3.10), including stillbirth (OR 4.55, 95% CI 1.53 to 13.50), spontaneous abortion (OR 2.05, 95% CI 1.40 to 3.00), preterm birth (OR 2.58, 95% CI 1.58 to 4.20), low birth weight (OR 2.64, 95% CI 1.61 to 4.34) and preeclampsia (OR 1.80, 95% CI 1.08 to 3.01). The odds of adverse pregnancy outcomes all increased after SLE diagnosis compared with before diagnosis, even after adjustment for age, years of education, pregnancy number and medical coverage.

Conclusion

From a large cohort of African–American women, our findings suggest there may be a predisease state that predisposes to adverse pregnancy outcomes.
Incidence and prevalence of lupus in Buenos Aires, Argentina: a 11-year health management organisation-based study
Authors: Scolnik M , Marin J , Valeiras S M , Marchese M F , Talani A S , Avellaneda N L , Etchepare A , Etchepare P , Plou M S , Soriano E R
Published: June 2014

Objectives

Studies regarding the epidemiology of systemic lupus erythematosus (SLE) are lacking in Argentina. Our purpose was to estimate the incidence and prevalence of SLE in a university hospital-based health management organisation in Buenos Aires (HIMCP).

Methods

For incidence calculation, the population at risk included all adult members of the HIMCP, with continuous affiliation for at least 1 year from January 1998 to January 2009. Each person was followed until he/she voluntarily left the HIMCP, death or finalisation of the study. Multiple methods for case finding were used to ensure complete ascertainment: (a) patients with problem SLE, undifferentiated autoimmune disease or mixed connective tissue disease in the Computer-based Patient Record System, (b) patients with positive antinuclear antibody test, anti-Sm antibodies and/or anti-dsDNA antibodies in the laboratory database and (c) patients who consumed hydroxichloroquine, chloroquine, azathioprine, cyclophosphamide, mycophenolate, cyclosporine or rituximab, from the administrative HIMCP drugs database. Medical records of all patients found were reviewed, and only patients fulfilling ACR criteria for SLE were included. Global and gender incidence rate (IR) was calculated. Prevalence was estimated on 1 January 2009, and the denominator population was the number of active members >18 years at that date (n=127 959).

Results

In the study period, 68 patients developed SLE. The observed IR (per 100 000 person-years, (CI 95%)) was 6.3 (4.9 to 7.7) for total population; 8.9 (CI 6.6 to 11.2) for women and 2.6 (1.2 to 3.9) for men. On 1 January 2009, 75 prevalent cases were identified. Prevalence rates (cases per 100 000 habitants, (CI 95%)) were 58.6 (46.1 to 73.5) for total population; 83.2 (63.9 to 106.4) for women and 23 (CI 11.9 to 40.1) for men.

Conclusions

SLE incidence and prevalence rates in Argentina are in agreement with those of other studies from different parts of the world.
Internet Use Among Incoming Undergraduate Students of Kuwait University
Authors: Alqudsi-ghabra Taghreed , Al-Dousari Elham
Published: June 2014

Information and technological skills instruction has been a lingering challenge for librarians and information professionals. Even though undergraduate incoming students to colleges and universities are a technology-savvy generation, evaluation of their Information Literacy (IL) and Technology Literacy (TL) skills might reveal a different situation. This research evaluates the familiarity and skills of the incoming class of undergraduate students of the College of Social Sciences at Kuwait University with Internet and other Social Media Networks (SMN). It seeks to investigate the relation to the educational background of the family and tries to ascertain the uses and means of accessing Internet and its various tools and practical implications on librarianship and the undergraduate curriculum.
Study of elastic moduli and thermal properties of RMnO3 (R = La, Nd) compounds
Authors: Varshney Dinesh , Choudhary Dinesh
Published: June 2014

In this paper, we develop a theoretical model for quantitative analysis of temperature-dependent heat capacity calculation of the magnetoresistance compounds RMnO 3 ( R = La , Nd ). The results on heat capacity obtained by us are in good agreement with the measured values. An effective interionic interaction potential (EIoIP) with the long-range Coulomb, van der Waals (vdW) interaction and short-range repulsive interaction up to second neighbor ions within the Hafemeister and Flygare approach was formulated to estimate the Debye and Einstein temperature and was found to be consistent with the available experimental data. In addition, the properties studied are the cohesive energy, molecular force constant, Restrahlen frequency and Gruneisen parameter. After characterizing thermal properties, a systematic investigation of elastic behavior has been undertaken and it has been found that the elastic moduli are decreasing continuously with increasing temperature.
Near-Regular Structure Discovery Using Linear Programming
Authors: Huang Qixing , Guibas Leonidas J. , Mitra Niloy J.
Published: June 2014

Near-regular structures are common in manmade and natural objects. Algorithmic detection of such regularity greatly facilitates our understanding of shape structures, leads to compact encoding of input geometries, and enables efficient generation and manipulation of complex patterns on both acquired and synthesized objects. Such regularity manifests itself both in the repetition of certain geometric elements, as well as in the structured arrangement of the elements. We cast the regularity detection problem as an optimization and efficiently solve it using linear programming techniques. Our optimization has a discrete aspect, that is, the connectivity relationships among the elements, as well as a continuous aspect, namely the locations of the elements of interest. Both these aspects are captured by our near-regular structure extraction framework, which alternates between discrete and continuous optimizations. We demonstrate the effectiveness of our framework on a variety of problems including near-regular structure extraction, structure-preserving pattern manipulation, and markerless correspondence detection. Robustness results with respect to geometric and topological noise are presented on synthesized, real-world, and also benchmark datasets.
Eliciting Predictions and Recommendations for Decision Making
Authors: Chen Yiling , Kash Ian A. , Ruberry Michael , Shnayder Victor
Published: June 2014

When making a decision, a decision maker selects one of several possible actions and hopes to achieve a desirable outcome. To make a better decision, the decision maker often asks experts for advice. In this article, we consider two methods of acquiring advice for decision making. We begin with a method where one or more experts predict the effect of each action and the decision maker then selects an action based on the predictions. We characterize
strictly
proper
decision making, where experts have an incentive to accurately reveal their beliefs about the outcome of each action. However, strictly proper decision making requires the decision maker use a completely mixed strategy to choose an action. To address this limitation, we consider a second method where the decision maker asks a single expert to recommend an action. We show that it is possible to elicit the decision maker’s most preferred action for a broad class of preferences of the decision maker, including when the decision maker is an expected value maximizer.
Data-driven Learner Modeling to Understand and Improve Online Learning
Authors: Koedinger Kenneth R. , McLaughlin Elizabeth A. , Stamper John C.
Published: June 2014

Advanced educational technologies are developing rapidly and online MOOC courses are becoming more prevalent, creating an enthusiasm for the seemingly limitless data-driven possibilities to affect advances in learning and enhance the learning experience. For these possibilities to unfold, the expertise and collaboration of many specialists will be necessary to improve data collection, to foster the development of better predictive models, and to assure models are interpretable and actionable. The big data collected from MOOCs needs to be bigger, not in its height (number of students) but in its width more meta-data and information on learners' cognitive and self-regulatory states needs to be collected in addition to correctness and completion rates. This more detailed articulation will help open up the black box approach to machine learning models where prediction is the primary goal. Instead, a data-driven learner model approach uses fine grain data that is conceived and developed from cognitive principles to build explanatory models with practical implications to improve student learning.
Signaling Schemes for Revenue Maximization
Authors: Emek Yuval , Feldman Michal , Gamzu Iftah , PaesLeme Renato , Tennenholtz Moshe
Published: June 2014

Signaling is an important topic in the study of asymmetric information in economic settings. In particular, the transparency of information available to a seller in an auction setting is a question of major interest. We introduce the study of signaling when conducting a second price auction of a probabilistic good whose actual instantiation is known to the auctioneer but not to the bidders. This framework can be used to model impressions selling in display advertising. We establish several results within this framework. First, we study the problem of computing a signaling scheme that maximizes the auctioneer’s revenue in a Bayesian setting. We show that this problem is polynomially solvable for some interesting special cases, but computationally hard in general. Second, we establish a tight bound on the minimum number of signals required to implement an optimal signaling scheme. Finally, we show that at least half of the maximum social welfare can be preserved within such a scheme.
Ex-Post Equilibrium and VCG Mechanisms
Authors: Rozen Rakefet , Smorodinsky Rann
Published: June 2014

Consider an abstract social choice setting with incomplete information, where the number of alternatives is large. Albeit natural, implementing VCG mechanisms is infeasible due to the prohibitive communication constraints. However, if players restrict attention to a subset of the alternatives, feasibility may be recovered.

This article characterizes the class of subsets that induce an ex-post equilibrium in the original game. It turns out that a crucial condition for such subsets to exist is the availability of a type-independent optimal social alternative for each player. We further analyze the welfare implications of these restrictions.

This work follows that of Holzman et al. [2004] and Holzman and Monderer [2004] where similar analysis is done for combinatorial auctions.
A novel, generalized recommender system for social media using the collaborative-filtering technique
Authors: A. Ramesh , J. Anusha , Tauro Clarence J.M.
Published: June 2014

Our goal in this paper is to discuss various methods available for Recommender Systems and describe an end-to-end approach for designing a Recommender System for social media using the collaborative-filtering approach. We will discuss the scope of contributions made in the recommender-system field, pros and cons for the collaborative-filtering approach, and current trends and challenges involved in the market with respect to the implementation of collaborative filtering.