bluuebunny/crossref_metadata_2025 huggingface dataset:
On Estimating the Reliability of Multiple Failure Region Problems Using Approximate Metamodels
Authors: Kuczera Ramon C. , Mourelatos Zissimos P.
Published: November 2009

In a complex system it is desirable to reduce the number of expensive function evaluations required for an accurate estimation of the probability of failure. An efficient reliability estimation method is presented for engineering systems with multiple failure regions and potentially multiple most probable points. The method can handle implicit nonlinear limit state functions with correlated or noncorrelated random variables, which can be described by any probabilistic distribution. It uses a combination of approximate or “accurate-on-demand,” global and local metamodels, which serve as indicators to determine the failure and safe regions. Sample points close to limit states define transition regions between safe and failure domains. A clustering technique identifies all transition regions, which can be, in general, disjoint, and local metamodels of the actual limit states are generated for each transition region. Importance sampling generates sample points only in the identified transition and failure regions, thus, allowing the method to focus on the areas near the failure region and not expend computational effort on the sample points in the safe domain. A robust maximin “space-filling” sampling technique is used to construct the metamodels. Two numerical examples highlight the accuracy and efficiency of the method.
Development of a Vehicle Modeling Function for Three-Dimensional Shape Optimization
Authors: Rho Joo-Hyun , Ku Yo-Cheon , Kee Jung-Do , Lee Dong-Ho
Published: November 2009

Representation of a complex three-dimensional (3D) shape requires extensive computer-aided design data consisting of millions (or tens of millions) of approximated discontinuous points. The quantity of data makes it difficult or impossible to efficiently optimize the entire shape. We present a vehicle-modeling function in the form of an exponential function to smoothly express the complex two-dimensional and 3D curved shapes of an automobile. This modeling function can modify and optimize the shape with fewer design variables compared with ordinary point-fitting methods. The subsectional parts of the vehicle-modeling function are defined as section functions by classifying each subsection of the automobile configuration as a section box model. The proposed approach is suitable for remodeling existing automobiles and for newly designed automobiles. The entire 3D aerodynamic shape of an automobile can be created using a set of the proposed modeling functions, which define a combination of section boxes. A 3D aerodynamic shape was developed to verify that the optimization of the shape was practical. This capability may help to reduce the developmental time or cost of automobiles and similarly complex systems. In addition, the proposed approach can be expanded to other fields of engineering.
Multiagent Shape Grammar Implementation: Automatically Generating Form Concepts According to a Preference Function
Authors: Orsborn Seth , Cagan Jonathan
Published: November 2009

In new product development, quickly generating many product form concepts that a potential consumer prefers is a challenge. This paper presents the inaugural multiagent shape grammar implementation (MASGI) to automatically generate product form designs according to a preference function that can represent designer or consumer design preference. Additionally, the multiagent system creates a flexible shape grammar implementation that enables modifications to the shape grammar as the form design space changes. The method is composed of three subprocesses: a shape grammar interpreter that implements the shape grammar, an agent system that chooses which shape grammar rules to implement and the parametric design choices according to a preference function, and a preference investigator that determines the preference function, which constraints the automated form design process.
Influence of Gerotor Performance in Varied Geometrical Design Parameters
Authors: Hsieh Chiu-Fan
Published: November 2009

Gerotor performance is influenced by sealing properties, area efficiency, contact stress, and outlet pressure. This paper uses the hypotrochoidal curve to generate the gerotor profile, and adopts the curvature difference method to assess the sealing property and predict the stress on the rotor profile. Numerical examples show that this method can successfully estimate and forecast the rotor sealing and the Hertz stress variation. For confirmation, these results are proved by theoretical stress calculations and software simulations. This paper also presents the results of sealing performance, stress variation, area efficiency, and outlet pressure for various geometrical design parameters. These results can serve as a pump performance reference, assisting designers wishing to create a better gerotor pump.
Design Optimization of Compliant Mechanisms Consisting of Standardized Elements
Authors: Jang Gang-Won , Kim Myung-Jin , Kim Yoon Young
Published: November 2009

We developed a design method to configure optimal compliant mechanisms consisting of standardized elements such as semirigid beams, hubs, and joints. In the proposed design approach, mechanism compliance is based upon elastic deformations of joint elements made of short elastic beams. To set up the design problem as an optimization problem, a standard ground beam-based topology optimization method is modified to handle compliant mechanisms comprised of design variable-independent semirigid beams and design variable-dependent elastic joints. In the proposed method, unlike structural stiffness maximization problems, intermediate values should appear to allow elastic deformations in the joints. With our approach, reconfiguration design from one existing compliant mechanism to another can be formulated wherein the number of beam element relocation operations is also minimized. This formulation can be useful in minimizing the time and effort required to convert one mechanism to another.
Coronary centerline extraction from CT coronary angiography images using a minimum cost path approach
Authors: Metz C. T. , Schaap M. , Weustink A. C. , Mollet N. R. , van Walsum T. , Niessen W. J.
Published: November 2009

Purpose:

The application and large‐scale evaluation of minimum cost path approaches for coronary centerline extraction from computed tomography coronary angiography (CTCA) data and the development and evaluation of a novel method to reduce the user‐interaction time.

Methods:

A semiautomatic method based on a minimum cost path approach is evaluated for two different cost functions. The first cost function is based on a frequently used vesselness measure and intensity information, and the second is a recently proposed cost function based on region statistics. User interaction is minimized to one or two mouse clicks distally in the coronary artery. The starting point for the minimum cost path search is automatically determined using a newly developed method that finds a point in the center of the aorta in one of the axial slices. This step ensures that all computationally expensive parts of the algorithm can be precomputed.

Results:

The performance of the aorta localization procedure was demonstrated by a success rate of 100% in 75 images. The success rate and accuracy of centerline extraction was quantitatively evaluated on 48 coronary arteries in 12 images by comparing extracted centerlines with a manually annotated reference standard. The method was able to extract 88% and 47% of the vessel centerlines correctly using the vesselness/intensity and region statistics cost function, respectively. For only the proximal part of the vessels these values were 97% and 86%, respectively. Accuracy of centerline extraction, defined as the average distance from correctly automatically extracted parts of the centerline to the reference standard, was 0.64 mm for the vesselness/intensity and 0.51 mm for the region statistics cost function. The interobserver variability was 99% for the success rate measure and 0.42 mm for the accuracy measure. Qualitative evaluation using the best performing cost function resulted in successful centerline extraction for 233 out of the 252 coronaries (92%) in 63 additional CTCA images.

Conclusions:

The presented results, in combination with minimal user interaction and low computation time, show that minimum cost path approaches can effectively be applied as a preprocessing step for subsequent analysis in clinical practice and biomedical research.
Correcting magnetic resonance ‐space data for in‐plane motion using an optical position tracking system
Authors: Marxen M. , Marmurek J. , Baker N. , Graham S. J.
Published: November 2009

Purpose

: Motion is a major confound of image quality in MRI. A method of retrospectively correcting the effects of rotations and translations on the acquired ‐space data is presented.

Methods:

In two phantom experiments of well‐controlled translation and rotation, two MRI‐compatible infrared cameras recorded motion data that were used subsequently to correct the position and phase of recorded‐space samples. Motion data can be acquired with a temporal resolution of 60 Hz and spatial accuracy of 0.1 mm for translations and 0.2° for rotations.

Results:

Significant improvements of image quality are demonstrated.

Conclusions:

The key advantages of the technique are that it is easy to implement, does not interfere with or complicate MR data acquisition, and is capable of correcting distortions within a single slice. Therefore, the technique has the potential to improve upon approaches that rely on the registration or realignment of successive imaging slices.
Registration of prone and supine CT colonography scans using correlation optimized warping and canonical correlation analysis
Authors: Wang Shijun , Yao Jianhua , Liu Jiamin , Petrick Nicholas , Van Uitert Robert L. , Periaswamy Senthil , Summers Ronald M.
Published: November 2009

Purpose:

In computed tomographic colonography (CTC), a patient will be scanned twice—Once supine and once prone—to improve the sensitivity for polyp detection. To assist radiologists in CTC reading, in this paper we propose an automated method for colon registration from supine and prone CTC scans.

Methods:

We propose a new colon centerline registration method for prone and supine CTC scans using correlation optimized warping (COW) and canonical correlation analysis (CCA) based on the anatomical structure of the colon. Four anatomical salient points on the colon are first automatically distinguished. Then correlation optimized warping is applied to the segments defined by the anatomical landmarks to improve the global registration based on local correlation of segments. The COW method was modified by embedding canonical correlation analysis to allow multiple features along the colon centerline to be used in our implementation.

Results:

We tested the COW algorithm on a CTC data set of 39 patients with 39 polyps (19 training and 20 test cases) to verify the effectiveness of the proposed COW registration method. Experimental results on the test set show that the COW method significantly reduces the average estimation error in a polyp location between supine and prone scans by 67.6%, from to , compared to the normalized distance along the colon centerline algorithm .

Conclusions:

The proposed COW algorithm is more accurate for the colon centerline registration compared to the normalized distance along the colon centerline method and the dynamic time warping method. Comparison results showed that the feature combination of‐coordinate and curvature achieved lowest registration error compared to the other feature combinations used by COW. The proposed method is tolerant to centerline errors because anatomical landmarks help prevent the propagation of errors across the entire colon centerline.
Optimizing non‐Pb radiation shielding materials using bilayers
Authors: McCaffrey J. P. , Mainegra‐Hing E. , Shen H.
Published: November 2009

Purpose:

The objective of this study was to demonstrate that the weight of non‐Pb radiation shielding materials can be minimized by structuring the material as a bilayer composed of different metal‐powder‐embedded elastomer layers.

Methods:

Measurements and Monte Carlo (MC) calculations were performed to study the attenuation properties of several non‐Pb metal bilayers over the x‐ray energy range 30–150 keV. Metals for the layers were chosen on the basis of low cost, nontoxicity, and complementary photoelectric absorption characteristics. The EGSnrc user code cavity.cpp was used to calculate the resultant x‐ray fluence spectra after attenuation by these metal layers. Air kerma attenuation was measured using commercially manufactured metal/elastomer test layers. These layers were irradiated using the primary standard calibration beams at the Institute for National Measurement Standards in Ottawa, Canada utilizing the six x‐ray beam qualities recommended in the German Standard DIN 6857. Both the measurements and the calculations were designed to approximate surface irradiation as well as penetrating radiation at 10 mm depth in soft tissue. The MC modeling point and the position of the measurement detector for surface irradiation were both directly against the downstream face of the attenuating material, as recommended in DIN 6857.

Results:

The low‐Z upstream/high‐Z downstream ordering of the metal bilayers provided substantially more attenuation than the reverse order. Optimal percentages of each metal in each bilayer were determined for each x‐ray radiation beam quality.

Conclusions:

Depending on the x‐ray quality, appropriate choices of two complementary metal‐embedded elastomer layers can decrease the weight of radiation shielding garments by up to 25% compared to Pb‐based elastomer garments while providing equivalent attenuation.
Influence of volumes of prostate, rectum, and bladder on treatment planning CT on interfraction prostate shifts during ultrasound image‐guided IMRTa)
Authors: Reddy Nandanuri M. S. , Nori Dattatreyudu , Sartin William , Maiorano Samuel , Modena Jennifer , Mazur Andrej , Osian Adrian , Sood Brijmohan , Ravi Akkamma , Sampath Seshadri , Lange Christopher S.
Published: November 2009

Purpose:

The purpose of this study was to analyze the relationship between prostate, bladder, and rectum volumes on treatment planning CT day and prostate shifts in the directions on treatment days.

Methods:

Prostate, seminal vesicles, bladder, and rectum were contoured on CT images obtained in supine position. Intensity modulated radiation therapy plans was prepared. Contours were exported to BAT‐ultrasound imaging system. Patients were positioned on the couch using skin marks. An ultrasound probe was used to obtain ultrasound images of prostate, bladder, and rectum, which were aligned with CT images. Couch shifts in the directions as recommended by BAT system were made and recorded. 4698 couch shifts for 42 patients were analyzed to study the correlations between interfraction prostate shifts vs bladder, rectum, and prostate volumes on planning CT.

Results:

Mean and range of volumes (cc): Bladder: 179 (42–582), rectum: 108 (28–223), and prostate: 55 (21–154). Mean systematic prostate shifts were (cm, ±SD) right and left lateral: (−0.361–0.251), anterior and posterior: (−0.466–0.669), and superior and inferior: (−0.342–0.633). Bladder volume was not correlated with lateral, anterior/posterior, and superior/inferior prostate shifts . Rectal volume was correlated with anterior/posterior but not with lateral and superior/inferior prostate shifts . The smaller the rectal volume or cross sectional area, the larger was the prostate shift anteriorly and vice versa . Prostate volume was correlated with superior/inferior but not with lateral and anterior/posterior prostate shifts . The smaller the prostate volume, the larger was prostate shift superiorly and vice versa .

Conclusions:

Prostate and rectal volumes, but not bladder volumes, on treatment planning CT influenced prostate position on treatment fractions. Daily image‐guided adoptive radiotherapy would be required for patients with distended or empty rectum on planning CT to reduce rectal toxicity in the case of empty rectum and to minimize geometric miss of prostate.
Science Signaling
Podcast: 24 November 2009
Authors: Pawson Tony , VanHook Annalisa M.
Published: November 2009

Bioinformatics analysis reveals how protein domain composition correlates with evolutionary change.
Lack of Bactericidal Antagonism or SynergismIn Vitrobetween Oxacillin and Vancomycin against Methicillin-Susceptible Strains ofStaphylococcus aureus
Authors: Joukhadar Christian , Pillai Satish , Wennersten Christine , Moellering Robert C. , Eliopoulos George M.
Published: November 2009

With the current high prevalence of infection caused by methicillin-resistantStaphylococcus aureus(MRSA) strains but in light of the general belief that β-lactam antibiotics are more effective than vancomycin against infections caused by methicillin-susceptibleS. aureus(MSSA) isolates, clinicians may utilize antistaphylococcal penicillins in combination with vancomycin for the empirical treatment ofS. aureusinfections. Vancomycin is considered to kill MSSA more slowly than oxacillin. Thus, we sought to evaluate the interaction of the combination of oxacillin and vancomycin on bacterial killingin vitro. Ten clinical isolates of MSSA isolated in the year 2000 were investigated. The killing observed at 24 h by vancomycin at 20 μg/ml, oxacillin at 16 μg/ml, or the combination did not differ (approximately 2.5 to 3.5 log10CFU/ml). In a separate experiment, we assessed bacterial killing in a dynamic model simulating the free plasma concentration profiles expected following the administration of a combination of vancomycin at 1 g every 12 h and oxacillin at 1 g every 6 h. The time-kill profiles of these regimens againstS. aureusATCC 29213 were comparable to those observed in the fixed-concentration experiments. Using these methods, we found no evidence that vancomycin antagonized the bactericidal effect of oxacillin or that there was any benefit from use of the combination.
Voriconazole Pharmacokinetics in Liver Transplant Recipients
Authors: Johnson H. J. , Han Kelong , Capitano B. , Blisard D. , Husain S. , Linden P. K. , Marcos A. , Kwak E. J. , Potoski B. , Paterson D. L. , Romkes M. , Venkataramanan R.
Published: November 2009

The objective of this study was to evaluate the pharmacokinetics of voriconazole and the potential correlations between pharmacokinetic parameters and patient variables in liver transplant patients on a fixed-dose prophylactic regimen. Multiple blood samples were collected within one dosing interval from 15 patients who were initiated on a prophylactic regimen of voriconazole at 200 mg enterally (tablets) twice daily starting immediately posttransplant. Voriconazole plasma concentrations were measured using high-pressure liquid chromatography (HPLC). Noncompartmental pharmacokinetic analysis was performed to estimate pharmacokinetic parameters. The mean apparent systemic clearance over bioavailability (CL/
F
), apparent steady-state volume of distribution over bioavailability (
V
ss
/
F
), and half-life (
t
1/2
) were 5.8 ± 5.5 liters/h, 94.5 ± 54.9 liters, and 15.7 ± 7.0 h, respectively. There was a good correlation between the area under the concentration-time curve from 0 h to infinity (AUC
0-∞
) and trough voriconazole plasma concentrations.
t
1/2
, maximum drug concentration in plasma (
C
max
), trough level, AUC
0-∞
, area under the first moment of the concentration-time curve from 0 h to infinity (AUMC
0-∞
), and mean residence time from 0 h to infinity (MRT
0-∞
) were significantly correlated with postoperative time.
t
1/2
, λ, AUC
0-∞
, and CL/
F
were significantly correlated with indices of liver function (aspartate transaminase [AST], total bilirubin, and international normalized ratio [INR]). The
C
max
, last concentration in plasma at 12 h (
C
last
), AUMC
0-∞
, and MRT
0-∞
were significantly lower in the presence of deficient
CYP2C19*2
alleles. Donor characteristics had no significant correlation with any of the pharmacokinetic parameters estimated. A fixed dosing regimen of voriconazole results in a highly variable exposure of voriconazole in liver transplant patients. Given that trough voriconazole concentration is a good measure of drug exposure (AUC), the voriconazole dose can be individualized based on trough concentration measurements in liver transplant patients.
Antimicrobial Peptide hLF1-11 Directs Granulocyte-Macrophage Colony-Stimulating Factor-Driven Monocyte Differentiation toward Macrophages with Enhanced Recognition and Clearance of Pathogens
Authors: van der Does Anne M. , Bogaards Sylvia J. P. , Ravensbergen Bep , Beekhuizen Henry , van Dissel Jaap T. , Nibbering Peter H.
Published: November 2009

The human lactoferrin-derived peptide hLF1-11 displays antimicrobial activities
in vitro
and is effective against infections with antibiotic-resistant bacteria and fluconazole-resistant
Candida albicans
in animals. However, the mechanisms underlying these activities remain largely unclear. Since hLF1-11 is ineffective
in vitro
at physiological salt concentrations, we suggested modulation of the immune system as an additional mechanism of action of the peptide. We investigated whether hLF1-11 affects human monocyte-macrophage differentiation and determined the antimicrobial activities of the resulting macrophages. Monocytes were cultured for 7 days with GM-CSF in the presence of hLF1-11, control peptide, or saline for various intervals. At day 6, the cells were stimulated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), or heat-killed
C. albicans
for 24 h. Thereafter, the levels of cytokines in the culture supernatants, the expression of pathogen recognition receptors, and the antimicrobial activities of these macrophages were determined. The results showed that a short exposure of monocytes to hLF1-11 during GM-CSF-driven differentiation is sufficient to direct differentiation of monocytes toward a macrophage subset characterized by both pro- and anti-inflammatory cytokine production and increased responsiveness to microbial structures. Moreover, these macrophages are highly effective against
C. albicans
and
Staphylococcus aureus
. In conclusion, hLF1-11 directs GM-CSF-driven differentiation of monocytes toward macrophages with enhanced effector functions.
Mode of Action of Van-M-02, a Novel Glycopeptide Inhibitor of Peptidoglycan Synthesis, in Vancomycin-Resistant Bacteria
Authors: Miura Kenji , Yamashiro Hidenori , Uotani Kouichi , Kojima Satoshi , Yutsudo Takashi , Lu Jun , Yoshida Osamu , Yamano Yoshinori , Maki Hideki , Arimoto Hirokazu
Published: November 2009

Van-M-02, a novel glycopeptide, was revealed to exert potent activities against Gram-positive bacteria, including vancomycin-resistant enterococci (VRE) and vancomycin-resistant
Staphylococcus aureus
(VRSA). A crude assay system was then used to study the mode of action of Van-M-02 as a peptidoglycan synthesis model of both vancomycin-susceptible and -resistant strains. The results suggested that Van-M-02 inhibits the synthesis of lipid intermediates irrespective of their termini. This inhibitory activity may contribute to the anti-VRE and anti-VRSA activities observed.
TMC278, a Next-Generation Nonnucleoside Reverse Transcriptase Inhibitor (NNRTI), Active against Wild-Type and NNRTI-Resistant HIV-1
Authors: Azijn Hilde , Tirry Ilse , Vingerhoets Johan , de Béthune Marie-Pierre , Kraus Guenter , Boven Katia , Jochmans Dirk , Van Craenenbroeck Elke , Picchio Gaston , Rimsky Laurence T.
Published: November 2009

Nonnucleoside reverse transcriptase inhibitors (NNRTIs) have proven efficacy against human immunodeficiency virus type 1 (HIV-1). However, in the setting of incomplete viral suppression, efavirenz and nevirapine select for resistant viruses. The diarylpyrimidine etravirine has demonstrated durable efficacy for patients infected with NNRTI-resistant HIV-1. A screening strategy used to test NNRTI candidates from the same series as etravirine identified TMC278 (rilpivirine). TMC278 is an NNRTI showing subnanomolar 50% effective concentrations (EC50values) against wild-type HIV-1 group M isolates (0.07 to 1.01 nM) and nanomolar EC50values against group O isolates (2.88 to 8.45 nM). Sensitivity to TMC278 was not affected by the presence of most single NNRTI resistance-associated mutations (RAMs), including those at positions 100, 103, 106, 138, 179, 188, 190, 221, 230, and 236. The HIV-1 site-directed mutant with Y181C was sensitive to TMC278, whereas that with K101P or Y181I/V was resistant.In vitro, considerable cross-resistance between TMC278 and etravirine was observed. Sensitivity to TMC278 was observed for 62% of efavirenz- and/or nevirapine-resistant HIV-1 recombinant clinical isolates. TMC278 inhibited viral replication at concentrations at which first-generation NNRTIs could not suppress replication. The rates of selection of TMC278-resistant strains were comparable among HIV-1 group M subtypes. NNRTI RAMs emerging in HIV-1 under selective pressure from TMC278 included combinations of V90I, L100I, K101E, V106A/I, V108I, E138G/K/Q/R, V179F/I, Y181C/I, V189I, G190E, H221Y, F227C, and M230I/L. E138R was identified as a new NNRTI RAM. Thesein vitroanalyses demonstrate that TMC278 is a potent next-generation NNRTI, with a high genetic barrier to resistance development.
Triclosan Resistance of
Pseudomonas aeruginosa
PAO1 Is Due to FabV, a Triclosan-Resistant Enoyl-Acyl Carrier Protein Reductase
Authors: Zhu Lei , Lin Jinshui , Ma Jincheng , Cronan John E. , Wang Haihong
Published: November 2009

Triclosan, a very widely used biocide, specifically inhibits fatty acid synthesis by inhibition of enoyl-acyl carrier protein (ACP) reductase.
Escherichia coli
FabI is the prototypical triclosan-sensitive enoyl-ACP reductase, and
E. coli
is extremely sensitive to the biocide. However, other bacteria are resistant to triclosan, because they encode triclosan-resistant enoyl-ACP reductase isozymes. In contrast, the triclosan resistance of
Pseudomonas aeruginosa
PAO1 has been attributed to active efflux of the compound (R. Chuanchuen, R. R. Karkhoff-Schweizer, and H. P. Schweizer, Am. J. Infect. Control
31:
124-127, 2003). We report that
P. aeruginosa
contains two enoyl-ACP reductase isozymes, the previously characterized FabI homologue plus a homologue of FabV, a triclosan-resistant enoyl-ACP reductase recently demonstrated in
Vibrio cholerae
. By deletion of the genes encoding
P. aeruginosa
FabI and FabV, we demonstrated that FabV confers triclosan resistance on
P. aeruginosa
. Upon deletion of the
fabV
gene, the mutant strain became extremely sensitive to triclosan (>2,000-fold more sensitive than the wild-type strain), whereas the mutant strain lacking FabI remained completely resistant to the biocide.
Micafungin Concentrations from Brain Tissue and Pancreatic Pseudocyst Fluid
Authors: Lat Asma , Thompson George R. , Rinaldi Michael G. , Dorsey Sheryl A. , Pennick Gennethel , Lewis James S.
Published: November 2009

We report the attainment of micafungin concentrations from brain tissue and pancreatic pseudocyst fluid from two patients with invasive candidiasis. Micafungin was present in low levels at both body sites, indicating limited penetration into central nervous system (CNS) tissue and pancreatic fluid. Further studies are needed to fully characterize its pharmacokinetics at these locations, as micafungin may potentially serve as an alternative antifungal therapy for CNS or pancreatic candidal infections for which the currently recommended first-line therapy fails.
The Virulence Transcriptional Activator AphA Enhances Biofilm Formation by
Vibrio cholerae
by Activating Expression of the Biofilm Regulator VpsT
Authors: Yang Menghua , Frey Erin M. , Liu Zhi , Bishar Rima , Zhu Jun
Published: November 2009

Vibrio cholerae
is the agent of the severe diarrheal disease cholera, and it perpetuates in aquatic reservoirs when not in the host. Within the host's intestines, the bacteria execute a complex regulatory pathway culminating with the production of virulence factors that allow colonization and cause disease. The ability of
V. cholerae
to form biofilms is thought to aid its persistence in the aquatic environment and passage through the gastric acid barrier of the stomach. The transcriptional activators VpsR and VpsT are part of the biofilm formation-regulatory network. In this study, we screened a
V. cholerae
genomic library in
Escherichia coli
cells containing a P

vpsT

-
luxCDBAE
transcriptional fusion reporter and found that a plasmid clone containing the
aphA
gene activates the expression of
vpsT
in
E. coli
. AphA is a master virulence regulator in
V. cholerae
that is required to activate the expression of
tcpP
, whose gene products in turn activate all virulence genes including those responsible for the synthesis of the toxin-coregulated pilus (TCP) and cholera toxin through the activation of
toxT
. AphA has a direct effect on the
vpsT
promoter, as gel shift experiments demonstrated that AphA binds to the
vpsT
promoter region. Furthermore,
V. cholerae aphA
mutants exhibit significantly lower levels of
vpsT
expression as well as reduced biofilm formation. AphA thus links the expression of virulence and biofilm synthesis genes.
Association of
Vibrio parahaemolyticus
Thermostable Direct Hemolysin with Lipid Rafts Is Essential for Cytotoxicity but Not Hemolytic Activity
Authors: Matsuda Shigeaki , Kodama Toshio , Okada Natsumi , Okayama Kanna , Honda Takeshi , Iida Tetsuya
Published: November 2009

Thermostable direct hemolysin (TDH), a major virulence factor of
Vibrio parahaemolyticus
, induces cytotoxicity in cultured cells. However, the mechanism of TDH's cytotoxic effect including its target molecules on the plasma membrane of eukaryotic cells remains unclear. In this study, we identified the role of lipid rafts, cholesterol- and sphingolipid-enriched microdomains, in TDH cytotoxicity. Treatment of cells with methyl-β-cyclodextrin (MβCD), a raft-disrupting agent, inhibited TDH cytotoxicity. TDH was associated with detergent-resistant membranes (DRMs), and MβCD eliminated this association. In contrast, there was no such association between a nontoxic TDH mutant and DRMs. The disruption of lipid rafts neither affected hemolysis nor inhibited Ca
2+
influx into HeLa cells induced by TDH. These findings indicate that the cytotoxicity but not the hemolytic activity of TDH is dependent on lipid rafts. The exogenous and endogenous depletion of cellular sphingomyelin also prevented TDH cytotoxicity, but a direct interaction between TDH and sphingomyelin was not detected with either a lipid overlay assay or a liposome absorption test. Treatment with sphingomyelinase (SMase) at 100 mU/ml disrupted the association of TDH with DRMs but did not affect the localization of lipid raft marker proteins (caveolin-1 and flotillin-1) with DRMs. These results suggest that sphingomyelin is important for the association of TDH with lipid rafts but is not a molecular target of TDH. We hypothesize that TDH may target a certain group of rafts that are sensitive to SMase at a certain concentration, which does not affect other types of rafts.
Health-related behaviours and sickness absence from work
Authors: Laaksonen M , Piha K , Martikainen P , Rahkonen O , Lahelma E
Published: November 2009

Objectives:

To compare associations of health-related behaviours with self-certified and medically confirmed sickness absence, and to examine whether these associations can be explained by psychosocial and physical working conditions and occupational social class.

Methods:

The study included 5470 female and 1464 male employees of the City of Helsinki surveyed in 2000–2002. These data were linked to sickness absence records until the end of 2005, providing a mean follow-up time of 3.9 years. Poisson regression analysis was used to examine associations of smoking, alcohol use, physical activity, dietary habits and relative weight (body mass index) with self-certified (1–3 days) and medically confirmed (⩾4 days) absence spells. Population attributable fractions (PAFs) were calculated to quantify the sickness absence burden related to the behaviours.

Results:

Smoking and high relative weight were most strongly associated with sickness absence, while the associations of other studied health-related behaviours were weaker. The associations were stronger for medically confirmed sickness absence spells for which heavy smoking and obesity more than doubled the risk of sickness absence in men and nearly doubled it in women. Adjusting for psychosocial working conditions had little or no effect on the associations. Physical working conditions and social class somewhat attenuated the associations, especially for smoking and relative weight. In self-certified sickness absence the PAF for smoking (16.4 in men, 10.3 in women) was largest, while in medically confirmed absence relative weight had the largest PAF (23.5 in men, 15.0 in women).

Conclusions:

Health-related behaviours, smoking and high relative weight in particular, were associated with subsequent sickness absence independently of psychosocial and physical working conditions and social class. Decreasing smoking and relative weight is likely to provide important gains in work ability and reduce sickness absence.
Evaluation of anti-obesity activity of duloxetine in comparison with sibutramine along with its anti-depressant activity: an experimental study in obese rats
Authors: Chudasama H.P. , Bhatt P.A.
Published: November 2009

5-HT and noradrenaline are important neurotransmitters that control increase in body mass and are involved in the pathophysiology of obesity and depression. Sibutramine, an established anti-obesity agent, and duloxetine, an anti-depressant agent, are serotonin noradrenaline reuptake inhibitors (SNRIs). The objective of the present study was to compare the anti-obesity effect of duloxetine with sibutramine along with its effect on blood pressure and depression in obese rats. The secondary objective of the study was to determine if a relationship exists between obesity and depression. Obesity was induced by high-fat diet (HFD) in healthy male Sprague–Dawley rats. After 5 weeks of feeding HFD, animals were overweight (17.57%) with high food intake (57.15%) in comparison with normal animals. These obese animals were treated with duloxetine (30 mg·kg–1, p.o.) and sibutramine (5 mg·kg–1, p.o.) for 4 weeks. Control animals were treated with duloxetine alone (30 mg·kg–1, p.o.). Our results depict that duloxetine was as effective as sibutramine in reducing food intake, body mass, and relative adiposity, and increasing rectal temperature with an added advantage of decreasing blood pressure, which sibutramine failed to do. Besides reduction in body mass, unlike sibutramine, duloxetine improved depressive state as evaluated by despair swimming test, tail suspension test, and open field test, speculating its use as an anti-obesity agent in obese-depressive animals. Since obese control animals reflected decreased locomotor activity, a positive relationship can be speculated to exist between obesity and depression. Further studies on various antidepressant models are required to confirm this relationship.
Hemodynamic and histomorphometric characteristics of heart failure induced by aortic stenosis in the guinea pig: comparison of two constriction sizes
Authors: Laviolle Bruno , Pape Danielle , Verdier Marie-Clémence , Lavenu Audrey , Bellissant Eric
Published: November 2009

Heart failure induced by aortic stenosis in young guinea pigs could constitute an interesting model for pharmacology, but its natural history needs to be characterized. One hundred five guinea pigs (3–4 weeks old) underwent thoracic aortic banding with 12- (B12G) or 14-gauge (B14G) needles or similar sham operations (S12G, S14G). Animals alive at 7 d (S12G, n = 16; B12G, n = 28; S14G, n = 19; B14G, n = 27) were assessed at 60 or 120 d. At 60 d, compared with sham groups, left ventricular (LV) mass and wall thickness increased in operated groups, but LV systolic pressure and right ventricular (RV) wall thickness only increased in the B14G group. At 120 d, B12G animals still showed signs of compensated hypertrophy with LV and RV wall thickening (+8%, +21%) and LV dilation (+20%), whereas B14G animals showed signs of decompensation with LV end-diastolic pressure increase (+167%) and mean arterial pressure decrease (–28%) associated with LV and RV hypertrophy (+77%, + 51%) and greater increases of LV and RV wall thickening (+19%, + 57%), as well as LV dilation (+43%). A 12G stenosis results in compensated hypertrophy at 60 and 120 d; a 14G stenosis leads to compensated hypertrophy at 60 d and heart failure at 120 d.
Aqueous extracts ofCimicifuga racemosaand phenolcarboxylic constituents inhibit production of proinflammatory cytokines in LPS-stimulated human whole blood
Authors: Schmid Diethart , Woehs Florian , Svoboda Martin , Thalhammer Theresia , Chiba Peter , Moeslinger Thomas
Published: November 2009

Cimicifuga racemosa (black cohosh) is commonly used in traditional medicines as treatment for menopausal symptoms and as an antiinflammatory remedy. To clarify the mechanism of action and active principle for the antiinflammatory action, the effects of aqueous C. racemosa root extracts (CRE) and its major constituents on the release of the proinflammatory cytokines IL-6, TNF-α, IFN-γ, and the chemokine IL-8 were investigated in lipopolysaccharide (LPS)-stimulated whole blood of healthy volunteers. CRE (3 µg/µL and 6 µg/µL) reduced LPS-induced release of IL-6 and TNF-α in a concentration- and time-dependent manner and almost completely blocked release of IFN-γ into the plasma supernatant. Except for IFN-γ, these effects were attenuated at longer incubation periods. IL-8 secretion was stimulated by CRE. As shown by quantitative real-time RT-PCR, effects on cytokines were based on preceding changes in mRNA levels except for IL-8. According to their content in CRE, the phenolcarboxylic compounds caffeic acid, ferulic acid, and isoferulic acid, as well as the triterpene glycosides 23-epi-26-deoxyactein and cimigenol-3-O-xyloside, were tested at representative concentrations. Among these, isoferulic acid was the prominent active principle in CRE, responsible for the observed inhibition of IL-6, TNF-α, and IFN-γ, but not for IL-8 stimulation. The effect of this compound may explain the antiinflammatory activities of CRE and its beneficial actions in rheumatism and other inflammatory diseases.
QUADRATIC EQUATIONS IN HILBERTIAN OPERATORS AND APPLICATIONS
Authors: MIZEL VICTOR J. , RAO M. M.
Published: November 2009

In this paper bounded linear operators in Hilbert space satisfying general quadratic equations are characterized. Necessary and sufficient conditions for sets of operators satisfying two such equations to compare relative to a weak ordering are presented. In addition, averaging operators in finite dimensional spaces are determined, and in this case it is shown that they are unitary models for all projections. It is pointed out, by an example, that the latter result does not hold in infinite dimensions. A key application to certain second order random fields of Karhunen type is given. The main purpose is to present the structure of bounded non-self adjoint operators solving quadratic equations, and indicate their use.
VARIATION OF THE POWER LAW EXPONENTS IN THE ANALYSIS OF UNIVERSAL DYNAMIC RESPONSE
Authors: LI TONGWEI , JU WEIWEI , GONG JIANGHONG
Published: November 2009

Frequency dependence of AC conductivity of four different solid electrolyte materials (covering electronic conduction, mixed conduction and ionic conduction) have been performed and the experimental data were analyzed according to a power law, which were frequently referred to as the so-called universal dynamic response (UDR). Results indicated for the four different materials, the power law exponent first decreases with increasing temperature. At a certain temperature, it exhibits a minimum and then increases again. For this novel phenomenon, the preliminary theoretical explanations and predictions also have been presented.
EFFECTS OF CONFINED LO AND SO PHONON MODES ON POLARON IN FREESTANDING CYLINDRICAL QUANTUM WIRE WITH PARABOLIC CONFINEMENT
Authors: ZOU ANYUN , XIE HONGJING
Published: November 2009

The electron self-energy and correction to the electron effective mass in a freestanding quantum wire with parabolic confining potential was investigated by the perturbation approach. Both the electron-confined longitudinal optical (LO) phonon and surface optical (SO) phonon interactions were considered. Results shows that, for small wire radius, the contributions of electron–LO phonon interaction to the electron self-energy and the correction to the electron effective mass are relatively small in compare with those of the electron–SO phonon interaction.
A PASSIVITY APPROACH TO SYNCHRONIZATION FOR TIME-DELAYED CHAOTIC SYSTEMS
Authors: AHN CHOON KI
Published: November 2009

In this letter, we propose a new passivity-based synchronization method for time-delayed chaotic systems. Based on Lyapunov–Krasovskii theory and linear matrix inequality (LMI) approach, the passivity-based controller is presented to make the synchronization error system for time-delayed chaotic systems not only passive but also asymptotically stable. The proposed controller can be obtained by solving a convex optimization problem represented by the LMI. As an application of the proposed method, the synchronization problem for chaotic delayed Hopfield neural networks is investigated.
NANO-VANADIUM DOPING-DRIVEN LOW TEMPERATURE STRUCTURAL PHASE TRANSFORMATION IN TITANIA
Authors: KUMAR ANUJ , GAHTORI BHASKER , KUMAR NEERAJ , AWANA V. P. S. , SRIVASTAVA A. K. , PANWAR NEERAJ , KISHAN H. , FELNER I.
Published: November 2009

Synthesis, X-ray diffraction (XRD), morphological, and magnetization studies of nano-vanadium doped TiO2are reported here. Commercially available anatase nano- TiO2and nano-vanadium powders were mixed and heat-treated in air at 600°C. X-ray diffraction revealed a complete anatase to rutile phase transformation at low vanadium content of 5%. Samples annealed under different environments such as Ar and O2also exhibited the same trend. Such a phase transformation at relatively low temperature (600°C) has been explained based on enhanced reactivity between vanadium and TiO2powders. Scanning electron micrographs elucidated the tunable microstructures from irregular-shaped, in the pristine TiO2(x=0.0), to well-faceted polyhedra V-doped (x=0.05 to 0.15) samples. Room temperature magnetization results revealed that upto 10% vanadium doping the samples are diamagnetic in nature and exhibit a paramagnetic transition for higher V content which presumably can be attributed to the presence of vanadium pentaoxide observed in the XRD.
A FLEXIBLE MICRO MANUFACTURING SYSTEM FOR MICRO PARTS ASSEMBLY VIA MICRO VISUAL SENSING AND EAP BASED GRASPING
Authors: UM DUGAN , ASIABANPOUR BAHRAM , JIMENEZ JESUS
Published: November 2009

In this paper, we developed a flexible micro workcell for micro part assembly and bio materials handling. The primary focus of the research is on the flexible manufacturing system that can handle parts in the size of 100 to 500 μm for various applications. Flexibility in micro assembly, though important, has not been examined in depth due to the complexity of micro operations of small parts. Micro gears, micro glass fibers or fragile bio materials require flexibility in gripping and haptic feedback control for further operation. To that end, we design grippers made out of electro active polymer, controlled by high precision micro manipulator for a novel micro assembly process, namely flexible micro assembly system (FMAS). The areas of research include micro/nano electro-mechanical system (MEMS) material and structure, micro sensor/actuator system, visual feedback control system, micro-robotic arm motion control and flexible micro-gripper system. In order to verify the functional aspect of the FMAS, we made micro mechanical gears fabricated via bulk micromachining technology for 3D micro vision capability and handling precision of micro robotic manipulator.
In the virtual extension
Authors: CACM Staff
Published: November 2009

Communications'
Virtual Extension brings more quality articles to ACM members. These articles are now available in the ACM Digital Library.
CS woes
Authors: Wing Jeannette M. , Guzdial Mark
Published: November 2009

The
Communications
Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish excerpts from selected posts.

Follow us on Twitter at http://twitter.com/blogCACM

Jeannette M. Wing writes about the negative effects of deadline-driven research and Mark Guzdial discusses the role of computer science faculty in fostering inequality.
Ready for a Web OS?
Authors: Wright Alex
Published: November 2009

A new generation of browsers may finally herald the long-awaited convergence of the Web and operating system.
Emerging marketsIsrael's technology industry as an economic growth engine
Authors: Berry Orna , Grayeff Yigal
Published: November 2009

How government-industry collaboration can have far-reaching economic influences.
The Bulk Multicore architecture for improved programmability
Authors: Torrellas Josep , Ceze Luis , Tuck James , Cascaval Calin , Montesinos Pablo , Ahn Wonsun , Prvulovic Milos
Published: November 2009

Easing the programmer's burden does not compromise system performance or increase the complexity of hardware implementation.
Computer science in the conceptual age
Authors: Zyda Michael
Published: November 2009

University CS departments are incorporating game design and development to prepare their students for the game industry's expectations.
Computer games and traditional CS courses
Authors: Sung Kelvin
Published: November 2009

Integrating computer games into existing CS courses may help attract students to the field, but there are guidelines to be considered.
Designing plush toys with a computer
Authors: Igarashi Yuki , Igarashi Takeo
Published: November 2009

We introduce Plushie, an interactive system that allows nonprofessional users to design their own original plush toys. To design a plush toy, one needs to construct an appropriate two-dimensional (2D) pattern. However, it is difficult for nonprofessional users to appropriately design a 2D pattern. Some recent systems automatically generate a 2D pattern for a given three-dimensional (3D) model, but constructing a 3D model is itself a challenge. Furthermore, an arbitrary 3D model cannot necessarily be realized as a real plush toy, and the final sewn result can be very different from the original 3D model. We avoid this mismatch by constructing appropriate 2D patterns and applying simple physical simulation to it on the fly during 3D modeling. In this way, the model on the screen is always a good approximation of the final sewn result, which makes the design process much more efficient. We use a sketching interface for 3D modeling and also provide various editing operations tailored for plush-toy design. Internally, the system constructs a 2D cloth pattern in such a way that the simulation result matches the user's input stroke. We successfully demonstrated that nonprofessional users could design plush toys or balloon easily using Plushie.
PuzzledSolutions and sources
Authors: Winkler Peter
Published: November 2009

Last month (November 2009, p. 112) we posted a trio of brain teasers, including one as yet unsolved, concerning the covering of a plane.