bluuebunny/crossref_metadata_2025 huggingface dataset:
A NOVEL MULTIPLEX PCR SYSTEM FOR THE DETECTION OF STAPHYLOCOCCAL ENTEROTOXIN B, TSST, NUC AND FEM GENES OF STAPHYLOCOCCUS AUREUS IN FOOD SYSTEM
Authors: SHYLAJA R. , MURALI H.S. , BATRA H.V. , BAWA A.S.
Published: March 2010

Staphylococcal enterotoxin B (SEB), toxic shock syndrome, the superantigens are responsible for diseases such as staphylococcal food poisoning and toxic shock syndrome. An easy and quick system is desirable to detect toxin‐producing strains. In this report, we described standardization of a novel multiplex‐polymerase chain reaction (PCR) assay for simultaneous detection of four important genes associated with the Staphylococcus aureus viz., SEB, Tsst, genus‐specific nuclease (nuc) and Fem genes along with an internal amplification control (IAC), which has now become mandatory in diagnostic PCRs, particularly when tested on environmental or food samples. This mPCR method is sensitive enough to detect cells as low as 103 cfu/mL or /g of the food samples. When evaluated on 136 food and environmental samples, the system detected 4 SEB‐positive S. aureus strains. The S. aureus strains that have been identified to contain the SEB gene in the mPCR were unequivocally detected for the toxin expression by the TECRA kit. mPCR produced a 100% correlation with conventional identification method. As SEB and Tsst are qualified as biowarfare molecules, this system is of immense help in detecting them during emergencies of biological war and suspected outbreaks of S. aureus food poisoning directly from the food and environmental samples.

PRACTICAL APPLICATIONS

The virulence‐associated genes targeted in this study are super antigenic in nature and are responsible for diseases such as staphylococcal food poisoning and toxic shock syndrome, and these molecules are also qualified as biowarfare agents. The high throughput and cost‐effective multiplex PCR method reported here could identify all these genes successfully from both artificially spiked and natural food samples and may also find its application in detection of these toxin‐producing Staphylococcus aureus from clinical and environmental samples.
Evolutionary Computation for Remote Sensing Applications
Authors: Easson Greg , Momm H. G.
Published: March 2010

As the volume of available remotely sensed imagery increases so does the need to extract more specific information in a timely and cost‐effective fashion to enhance and/or update decision support systems. This manuscript provides an overview of the existing image information extraction techniques using evolutionary computation algorithms. Emphasis is given to remote sensing applications. The literature investigated is further divided into four groups based on the research objectives: image enhancement, image classification, feature extraction, and modeling. Some of the strengths of evolutionary computation are discussed, such as robust classification capabilities and ability to work with linear and non‐linear problems. Conversely, the works reviewed reveal some of the challenges in the integration of evolutionary computation and remote sensing as well as possible solutions. Limited work was found addressing the multi‐class image classification problem and assessment of the randomness involved in the generation of the first set of candidate solutions from which the algorithm begins. Based on our study, the use of evolutionary computation algorithms for information extraction from imagery is likely to grow, specifically in two areas: inverse modeling and object‐based approaches. This technology is still in its early stages of development and the capabilities of evolutionary computation are well suited to the complexities of the image processing and information extraction problems.
Role of fungal trehalose and bacterial thiamine in the improved survival and growth of the ectomycorrhizal fungus Laccaria bicolor S238N and the helper bacterium Pseudomonas fluorescens BBc6R8
Authors: Deveau A. , Brulé C. , Palin B. , Champmartin D. , Rubini P. , Garbaye J. , Sarniguet A. , Frey‐Klett P.
Published: March 2010

The mycorrhiza helper bacterial strain Pseudomonas fluorescens BBc6R8 enhances the establishment of Laccaria bicolor S238N ectomycorrhizae by improving the pre‐symbiotic growth and survival of the fungus. Nothing is known about the effect of the ectomycorrhizal fungus on the helper bacteria or the molecules that are involved in the interaction. In this study, we have monitored the population density of the helper strain P. fluorescens BBc6R8 in soils inoculated with L. bicolor and in control soils and found that the ectomycorhizal fungus improves the survival of the helper bacteria. We investigated the identity of the fungal and bacterial metabolites involved in this reciprocal growth‐promoting effect using a combination of growth measurements, chemoattractant assays, HPLC and in silico genome analyses. We showed that trehalose, a disaccharide that accumulates to high levels in the fungal hyphae, chemoattracted and promoted the growth of the helper bacteria. Meanwhile, P. fluorescens BBc6R8 produced thiamine at concentrations that enhanced the fungal growth in vitro. Altogether our data indicate that the interaction between the two microorganisms is beneficial for both species and relies, at least in part, on trophic mutualism.
CTX‐M‐15‐type extended‐spectrum beta‐lactamases‐producing Escherichia coli from wild birds in Germany
Authors: Guenther Sebastian , Grobbel Mirjam , Beutlich Janine , Bethe Astrid , Friedrich Nicole D. , Goedecke Andreas , Lübke‐Becker Antina , Guerra Beatriz , Wieler Lothar H. , Ewers Christa
Published: March 2010

The isolation of Escherichia coli from wild birds in Germany revealed the occurrence of four CTX‐M‐15‐producing strains from four different birds (2.3% of 172 isolates). CTX‐M producers were recovered from two Eurasian Blackbirds, one Rock Pigeon and a Greater White‐fronted Goose. All CTX‐M‐producing E. coli revealed a clonal relationship as determined by pulsed‐field gel electrophoresis (PFGE) and were assigned to multilocus sequence type (ST) 648. Our findings suggest the emergence of a new clone with epidemiological importance and strengthen the role of wild bird species other than waterfowl as possible reservoirs of ESBL‐producing Enterobacteriaceae.
Quantitative dopant profiling of p-n junction in InGaAs∕AlGaAs light-emitting diode using off-axis electron holography
Authors: Chung Suk , Johnson Shane R. , Ding Ding , Zhang Yong-Hang , Smith David J. , McCartney Martha R.
Published: March 2010

The electrostatic potential profile across the p-n junction of an InGaAs light-emitting diode with linearly graded AlGaAs triangular barriers has been measured using off-axis electron holography. Simulations of the junction profile show small discrepancies with experimental measurements in the region of the p-and n-doped AlGaAs barriers, which are located away from the InGaAs quantum wells. Revised simulations reproduce the measurements reasonably when a carrier-trap density of 6×1016cm−3 in the AlGaAs barriers is subtracted from the dopant concentrations. The presence of oxygen impurities is considered as the most likely reason for the reduction in doping efficiency.
Plasma doping two-dimensional characterization using low energy x-ray emission spectroscopy and full wafer secondary ion mass spectrometry/angle-resolved x-ray electron spectroscopy techniques
Authors: Qin Shu , Morinville Wendy , Zhuang Kent , Fabreguette Francois , McTeer Allen , Hu Y. Jeff , Lu Shifeng
Published: March 2010

Several metrologies may be used to analyze plasma doping (PLAD) [S. Qin and A. McTeer, IEEE Trans. Electron Devices 54, 2497 (2007)] results, each with its own advantages and disadvantages. An investigation into the available characterization methods has been performed in order to reduce costs associated with the current qualification process, such as additional clean and annealing steps. This article will introduce an improved analytical method developed at Micron and demonstrate results of a correlation study between characterization techniques for B doped PLAD. The combined secondary ion mass spectrometry/angle-resolved x-ray electron spectroscopy two-dimensional (2D) dose mapping data provide excellent confirmation of the low energy x-ray emission spectroscopy (LEXES) 2D dose mapping data, and the nonuniformity from annealing can be deconvoluted from nonuniformities due to the implantation process. The data demonstrate that LEXES may replace the thermally processed RS measurement for tool and/or process qualifications.
Monte Carlo calculated absorbed‐dose energy dependence of EBT and EBT2 film
Authors: Sutherland J. G. H. , Rogers D. W. O.
Published: March 2010

Purpose:

The absorbed‐dose energy dependence of GAFCHROMIC EBT and EBT2 film irradiated in photon beams is studied to understand the shape of the curves and the physics behind them.

Methods:

The absorbed‐dose energy dependence is calculated using the EGSnrc‐based EGS_chamber and DOSRZnrc codes by calculating the ratio of dose to water to dose to active film layers at photon energies ranging from 3 keV to 18 MeV. These data are compared to the mass energy absorption coefficient ratios and the restricted stopping power ratios of water to active film materials as well as to previous experimental results.

Results:

In the photon energy range of 100 keV to 18 MeV the absorbed‐dose energy dependence is found to be energy independent within ±0.6%. However, below 100 keV, the absorbed‐dose energy dependence of EBT varies by approximately 10% due to changes in mass energy absorption coefficient ratios of water to film materials, as well as an increase in the number of electrons being created and scattered in the central surface layer of the film. Results are found to disagree with previous experimental studies suggesting the possibility of an intrinsic energy dependence at lower photon energies. For EBT2 film the absorbed‐dose energy dependence at low photon energies varies by 50% or 10% depending on the manufacturing lot due to changes in the ratio of mass energy absorption coefficients of the active emulsion layers to water.

Conclusions:

Caution is recommended when using GAFCHROMIC EBT/EBT2 films at photon energies below 100 keV. It is recommended that the effective atomic number of future films be produced as close to that of water and that thicker active layers are advantageous.
A convolution‐superposition dose calculation engine for GPUs
Authors: Hissoiny Sami , Ozell Benoît , Després Philippe
Published: March 2010

Purpose:

Graphic processing units (GPUs) are increasingly used for scientific applications, where their parallel architecture and unprecedented computing power density can be exploited to accelerate calculations. In this paper, a new GPU implementation of a convolution/superposition (CS) algorithm is presented.

Methods:

This new GPU implementation has been designed from the ground‐up to use the graphics card's strengths and to avoid its weaknesses. The CS GPU algorithm takes into account beam hardening, off‐axis softening, kernel tilting, and relies heavily on raytracing through patient imaging data. Implementation details are reported as well as a multi‐GPU solution.

Results:

An overall single‐GPU acceleration factor of 908× was achieved when compared to a nonoptimized version of the CS algorithm implemented in PlanUNC in single threaded central processing unit (CPU) mode, resulting in approximatively 2.8 s per beam for a 3D dose computation on a 0.4 cm grid. A comparison to an established commercial system leads to an acceleration factor of approximately 29× or 0.58 versus 16.6 s per beam in single threaded mode. An acceleration factor of 46× has been obtained for the total energy released per mass (TERMA) calculation and a 943× acceleration factor for the CS calculation compared to PlanUNC. Dose distributions also have been obtained for a simple water‐lung phantom to verify that the implementation gives accurate results.

Conclusions:

These results suggest that GPUs are an attractive solution for radiation therapy applications and that careful design, taking the GPU architecture into account, is critical in obtaining significant acceleration factors. These results potentially can have a significant impact on complex dose delivery techniques requiring intensive dose calculations such as intensity‐modulated radiation therapy (IMRT) and arc therapy. They also are relevant for adaptive radiation therapy where dose results must be obtained rapidly.
Accurate brain volumetry with diffusion‐weighted spin‐echo single‐shot echo‐planar‐imaging and dual‐clustering segmentation: Comparison with volumetry‐validated quantitative magnetic resonance imaging
Authors: Watanabe Memi , Sakai Osamu , Norbash Alexander M. , Jara Hernán
Published: March 2010

Purpose:

Although the diffusion‐weighted spin‐echo single‐shot echo‐planar‐imaging (DW‐SE‐sshEPI) is an established quantitative MRI (qMRI) pulse sequence, it is known to be vulnerable to geometric distortions. The purpose of this work is to study is to study brain volumetry accuracy with DW‐SE‐sshEPI relative previously published volumetry‐validated qMRI pulse sequence, specifically the mixed turbo spin‐echo (mixed‐TSE) pulse sequence, which is robust to magnetic field inhomogeneities and affords much higher spatial resolution.

Methods:

Twenty‐eight subjects were imaged with both DW‐SE‐sshEPI and mixed‐TSE pulse sequences. For each subject, the intracranial structures were segmented using a single‐qMRI‐channel dual‐clustering algorithm (for DW‐SE‐sshEPI) and a three‐qMRI‐channel dual‐clustering algorithm (for mixed‐TSE). The respective intracranial volumes were calculated with both data sets and then compared.

Results:

The intracranial volumes derived from DW‐SE‐sshEPI and mixed‐TSE data sets are highly and linearly correlated with a slope of 0.9911, with one distorted DW‐SE‐sshEPI data set demonstrating remarkable volume underestimation. Excluding this outlier resulted in improved linear correlation with a slope of 1.0003.

Conclusions:

Brain volumetry with DW‐SE‐sshEPI at 1.5 T data sets can be very accurate for most patients for whom the major magnetic field inhomogeneities result from typical tissue interfaces (e.g., air‐tissue or bone‐tissue) and typical dental fillings, but not from larger metallic implants.
Evaluation of respiration‐correlated digital tomosynthesis in lunga)
Authors: Santoro Joseph , Kriminski Sergey , Lovelock D. Michael , Rosenzweig Kenneth , Mostafavi Hassan , Amols Howard I. , Mageras Gig S.
Published: March 2010

Digital tomosynthesis (DTS) with a linear accelerator‐mounted imaging system provides a means of reconstructing tomographic images from radiographic projections over a limited gantry arc, thus requiring only a few seconds to acquire. Its application in the thorax, however, often results in blurred images from respiration‐induced motion. This work evaluates the feasibility of respiration‐correlated (RC) DTS for soft‐tissue visualization and patient positioning. Image data acquired with a gantry‐mounted kilovoltage imaging system while recording respiration were retrospectively analyzed from patients receiving radiotherapy for non‐small‐cell lung carcinoma. Projection images spanning an approximately 30° gantry arc were sorted into four respiration phase bins prior to DTS reconstruction, which uses a backprojection, followed by a procedure to suppress structures above and below the reconstruction plane of interest. The DTS images were reconstructed in planes at different depths through the patient and normal to a user‐selected angle close to the center of the arc. The localization accuracy of RC‐DTS was assessed via a comparison with CBCT. Evaluation of RC‐DTS in eight tumors shows visible reduction in image blur caused by the respiratory motion. It also allows the visualization of tumor motion extent. The best image quality is achieved at the end‐exhalation phase of the respiratory motion. Comparison of RC‐DTS with respiration‐correlated cone‐beam CT in determining tumor position, motion extent and displacement between treatment sessions shows agreement in most cases within 2–3 mm, comparable in magnitude to the intraobserver repeatability of the measurement. These results suggest the method's applicability for soft‐tissue image guidance in lung, but must be confirmed with further studies in larger numbers of patients.
Of Mice and Men: How an Oncogene Transgresses the Limits and Predisposes to T Cell Acute Lymphoblastic Leukemia
Authors: Hoang Trang
Published: March 2010

The
Lmo2
oncogene confers self-renewal potential on
nonrenewing thymocyte progenitors.
Detection and Genetic Analysis of Human Sapoviruses in River Water in Japan
Authors: Kitajima Masaaki , Oka Tomoichiro , Haramoto Eiji , Katayama Hiroyuki , Takeda Naokazu , Katayama Kazuhiko , Ohgaki Shinichiro
Published: February 2010

We investigated the prevalence of sapoviruses (SaVs) in the Tamagawa River in Japan from April 2003 to March 2004 and performed genetic analysis of the SaV genes identified in river water. A total of 60 river water samples were collected from five sites along the river, and 500 ml was concentrated using the cation-coated filter method. By use of a real-time reverse transcription (RT)-PCR assay, 12 (20%) of the 60 samples were positive for SaV. SaV sequences were obtained from 15 (25%) samples, and a total of 30 SaV strains were identified using six RT-PCR assays followed by cloning and sequence analysis. A newly developed nested RT-PCR assay utilizing a broadly reactive forward primer showed the highest detection efficiency and amplified more diverse SaV genomes in the samples. SaV sequences were frequently detected from November to March, whereas none were obtained in April, July, September, or October. No SaV sequences were detected in the upstream portion of the river, whereas the midstream portion showed high positive rates. Based on phylogenetic analysis, SaV strains identified in the river water samples were classified into nine genotypes, namely, GI/1, GI/2, GI/3, GI/5, GI/untyped, GII/1, GII/2, GII/3, and GV/1. To our knowledge, this is the first study describing seasonal and spatial distributions and genetic diversity of SaVs in river water. A combination of real-time RT-PCR assay and newly developed nested RT-PCR assay is useful for identifying and characterizing SaV strains in a water environment.
Siderophores Are Not Involved in Fe(III) Solubilization during Anaerobic Fe(III) Respiration by
Shewanella oneidensis
MR-1
Authors: Fennessey Christine M. , Jones Morris E. , Taillefert Martial , DiChristina Thomas J.
Published: February 2010

Shewanella oneidensis
MR-1 respires a wide range of anaerobic electron acceptors, including sparingly soluble Fe(III) oxides. In the present study,
S. oneidensis
was found to produce Fe(III)-solubilizing organic ligands during anaerobic Fe(III) oxide respiration, a respiratory strategy postulated to destabilize Fe(III) and produce more readily reducible soluble organic Fe(III). In-frame gene deletion mutagenesis, siderophore detection assays, and voltammetric techniques were combined to determine (i) if the Fe(III)-solubilizing organic ligands produced by
S. oneidensis
during anaerobic Fe(III) oxide respiration were synthesized via siderophore biosynthesis systems and (ii) if the Fe(III)-siderophore reductase was required for respiration of soluble organic Fe(III) as an anaerobic electron acceptor. Genes predicted to encode the siderophore (hydroxamate) biosynthesis system (SO3030 to SO3032), the Fe(III)-hydroxamate receptor (SO3033), and the Fe(III)-hydroxamate reductase (SO3034) were identified in the
S. oneidensis
genome, and corresponding in-frame gene deletion mutants were constructed. ΔSO3031 was unable to synthesize siderophores or produce soluble organic Fe(III) during aerobic respiration yet retained the ability to solubilize and respire Fe(III) at wild-type rates during anaerobic Fe(III) oxide respiration. ΔSO3034 retained the ability to synthesize siderophores during aerobic respiration and to solubilize and respire Fe(III) at wild-type rates during anaerobic Fe(III) oxide respiration. These findings indicate that the Fe(III)-solubilizing organic ligands produced by
S. oneidensis
during anaerobic Fe(III) oxide respiration are not synthesized via the hydroxamate biosynthesis system and that the Fe(III)-hydroxamate reductase is not essential for respiration of Fe(III)-citrate or Fe(III)-nitrilotriacetic acid (NTA) as an anaerobic electron acceptor.
Multilocus Sequence Type Analysis Reveals both Clonality and Recombination in Populations of Candida glabrata Bloodstream Isolates from U.S. Surveillance Studies
Authors: Lott Timothy J. , Frade João P. , Lockhart Shawn R.
Published: February 2010

The human commensal yeast
Candida glabrata
is becoming increasingly important as an agent of nosocomial bloodstream infection. However, relatively little is known concerning the genetics and population structure of this species. We have analyzed 230 incident bloodstream isolates from previous and current population-based surveillance studies by using multilocus sequence typing (MLST). Our results show that in the U.S. cities of Atlanta, GA; Baltimore, MD; and San Francisco, CA during three time periods spanning 1992 to 2009, five populations of
C. glabrata
bloodstream isolates are defined by a relatively small number of sequence types. There is little genetic differentiation in the different
C. glabrata
populations. We also show that there has been a significant temporal shift in the prevalence of one major subtype in Atlanta. Our results support the concept that both recombination and clonality play a role in the population structure of this species.
Kinetic Characterization of the WalRKSpn(VicRK) Two-Component System ofStreptococcus pneumoniae: Dependence of WalKSpn(VicK) Phosphatase Activity on Its PAS Domain
Authors: Gutu Alina D. , Wayne Kyle J. , Sham Lok-To , Winkler Malcolm E.
Published: February 2010

The WalRK two-component system plays important roles in maintaining cell wall homeostasis and responding to antibiotic stress in low-GC Gram-positive bacteria. In the major human pathogen,Streptococcus pneumoniae, phosphorylated WalRSpn(VicR) response regulator positively controls the transcription of genes encoding the essential PcsB division protein and surface virulence factors. WalRSpnis phosphorylated by the WalKSpn(VicK) histidine kinase. Little is known about the signals sensed by WalK histidine kinases. To gain information about WalKSpnsignal transduction, we performed a kinetic characterization of the WalRKSpnautophosphorylation, phosphoryltransferase, and phosphatase reactions. We were unable to purify soluble full-length WalKSpn. Consequently, these analyses were performed using two truncated versions of WalKSpnlacking its single transmembrane domain. The longer version (Δ35 amino acids) contained most of the HAMP domain and the PAS, DHp, and CA domains, whereas the shorter version (Δ195 amino acids) contained only the DHp and CA domains. The autophosphorylation kinetic parameters of Δ35 and Δ195 WalKSpnwere similar [Km(ATP) ≈ 37 μM;kcat≈ 0.10 min−1] and typical of those of other histidine kinases. The catalytic efficiency of the two versions of WalKSpn∼P were also similar in the phosphoryltransfer reaction to full-length WalRSpn. In contrast, absence of the HAMP-PAS domains significantly diminished the phosphatase activity of WalKSpnfor WalRSpn∼P. Deletion and point mutations confirmed that optimal WalKSpnphosphatase activity depended on the PAS domain as well as residues in the DHp domain. In addition, these WalKSpnDHp domain and ΔPAS mutations led to attenuation of virulence in a murine pneumonia model.
A LOW-VOLTAGE LOW-POWER 10-BIT 200 MS/S PIPELINED ADC IN 90 NM CMOS
Authors: ABDINIA SAHEL , YAVARI MOHAMMAD
Published: March 2010

This paper presents a low-power 10-bit 200 MS/s pipelined ADC in a 90 nm CMOS technology with 1 V supply voltage. To decrease the power dissipation efficiently, a new architecture using a combination of two power reduction techniques named double-sampling and opamp-sharing has been used to reduce the power consumption significantly, without any degradation in the performance of the ADC. In addition, the stage scaling technique has been applied to the ADC efficiently, and two-stage class A/AB and class A amplifiers and dynamic comparators have been used in sample and hold and sub-ADCs. According to HSPICE simulation results, the 10-bit 200 MSample/s pipeline ADC with a 9.375 MHz, 1-VP-P,diff input signal in a 90 nm CMOS process achieves a SNDR of 58.5 dB while consuming only 30.9 mW power from a 1 V supply voltage.
A PARAMETRIC SLANT-HADAMARD SYSTEM FOR ROBUST IMAGE WATERMARKING
Authors: LATIF ALIMOHAMMAD , NAGHSH-NILCHI AHMAD REZA , MONADJEMI S. AMIRHASAN
Published: March 2010

In this paper, a novel watermarking technique based on parametric slant-Hadamard transform is presented. Our approach embeds a pseudo-random sequence of real numbers in a selected set of the parametric slant-Hadamard transform coefficients. By exploiting statistical properties of the embedded sequence, the mark can be reliably extracted without resorting to the original uncorrupted image. The presented method is capable of increasing the flexibility of the watermarking scheme, where the changes in parameter set help to improve fidelity and robustness against a number of attacks. Experimental results show that the proposed technique is secure and indeed highly robust to these attacks.
GEOMETRIC STREAMING ALGORITHM WITH A SORTING PRIMITIVE
Authors: CHEN ERIC Y.
Published: March 2010

We solve several fundamental geometric problems under a new streaming model recently proposed by Ruhl et al.2,15In this model, in one pass the input stream can be scanned to generate an output stream or be sorted based on a user-defined comparator; all intermediate streams must be of size O(n). We obtain the following geometric results for any fixed constant ϵ > 0:

• We can construct 2D convex hulls in O(1) passes with O(nϵ) extra space.

• We can construct 3D convex hulls in O(1) expected number of passes with O(nϵ) extra space.

• We can construct a triangulation of a simple polygon in O(1) expected number of passes with O(nϵ) extra space, where n is the number of vertices on the polygon.

• We can report all k intersections of a set of 2D line segments in O(1) passes with O(nϵ) extra space, if an intermediate stream of size O(n + k) is allowed.

We also consider a weaker model, where we do not have the sorting primitive but are allowed to choose a scan direction for every scan pass. Here we can construct a 2D convex hull from an x-ordered point set in O(1) passes with O(nϵ) extra space.
DILATION-OPTIMAL EDGE DELETION IN POLYGONAL CYCLES
Authors: AHN HEE-KAP , FARSHI MOHAMMAD , KNAUER CHRISTIAN , SMID MICHIEL , WANG YAJUN
Published: March 2010

Consider a geometric network G in the plane. The dilation between any two vertices x and y in G is the ratio of the shortest path distance between x and y in G to the Euclidean distance between them. The maximum dilation over all pairs of vertices in G is called the dilation of G. In this paper, a randomized algorithm is presented which, when given a polygonal cycle C on n vertices in the plane, computes in O(n log 3 n) expected time, the edge of C whose removal results in a polygonal path of smallest possible dilation. It is also shown that the edge whose removal gives a polygonal path of largest possible dilation can be computed in O(n log n) time. If C is a convex polygon, the running time for the latter problem becomes O(n). Finally, it is shown that a (1 - ϵ)-approximation to the dilation of every path C \{e}, for all edges e of C, can be computed in O(n log n) total time.
On Thermal Stability of Topological Qubit in Kitaev's 4D Model
Authors: Alicki R. , Horodecki M. , Horodecki P. , Horodecki R.
Published: March 2010

We analyse stability of the four-dimensional Kitaev model — a candidate for scalable quantum memory — in finite temperature within the weak coupling Markovian limit. It is shown that, below a critical temperature, certain topological qubit observables X and Z possess relaxation times exponentially long in the size of the system. Their construction involves polynomial in system size algorithm which uses as an input the results of measurements performed on all individual spins. We also discuss the drawbacks of such candidate for quantum memory and mention the implications of the stability of qubit for statistical mechanics.
Exendin-4 increases blood glucose levels acutely in rats by activation of the sympathetic nervous system
Authors: Pérez-Tilve Diego , González-Matías Lucas , Aulinger Benedikt A. , Alvarez-Crespo Mayte , Gil-Lozano Manuel , Alvarez Elias , Andrade-Olivie Amalia M. , Tschöp Matthias H. , D'Alessio David A. , Mallo Federico
Published: March 2010

Exendin-4 (Ex-4), an agonist of the glucagon-like peptide-1 receptor (GLP-1R), shares many of the actions of GLP-1 on pancreatic islets, the central nervous system (CNS), and the gastrointestinal tract that mediates glucose homeostasis and food intake. Because Ex-4 has a much longer plasma half-life than GLP-1, it is an effective drug for reducing blood glucose levels in patients with type 2 diabetes mellitus (T2DM). Here, we report that acute administration of Ex-4, in relatively high doses, into either the peripheral circulation or the CNS, paradoxically increased blood glucose levels in rats. This effect was independent of the insulinotropic and hypothalamic-pituitary-adrenal activating actions of Ex-4 and could be blocked by a GLP-1R antagonist. Comparable doses of GLP-1 did not induce hyperglycemia, even when protected from rapid metabolism by a dipeptidyl peptidase IV inhibitor. Acute hyperglycemia induced by Ex-4 was blocked by hexamethonium, guanethidine, and adrenal medullectomy, indicating that this effect was mediated by sympathetic nervous system (SNS) activation. The potency of Ex-4 to elevate blood glucose waned with chronic administration such that after 6 days the familiar actions of Ex-4 to improve glucose tolerance were evident. These findings indicate that, in rats, high doses of Ex-4 activate a SNS response that can overcome the expected benefits of this peptide on glucose metabolism and actually raise blood glucose. These results have important implications for the design and interpretation of studies using Ex-4 in rats. Moreover, since there are many similarities in the response of the GLP-1R system across mammalian species, it is important to consider whether there is acute activation of the SNS by Ex-4 in humans.
Angiotensin-(1–7) stimulates high atrial pacing-induced ANP secretion via Mas/PI3-kinase/Akt axis and Na+/H+exchanger
Authors: Shah Amin , Gul Rukhsana , Yuan Kuichang , Gao Shan , Oh Young-Bin , Kim Uh-Hyun , Kim Suhn Hee
Published: February 2010

Angiotensin-(1–7) [ANG-(1–7)], one of the bioactive peptides produced in the renin-angiotensin system, plays a pivotal role in cardiovascular physiology by providing a counterbalance to the function of ANG II. Recently, it has been considered as a potential candidate for therapeutic use in the treatment of various types of cardiovascular diseases. The aim of the present study is to explain the modulatory role of ANG-(1–7) in atrial natriuretic peptide (ANP) secretion and investigate the functional relationship between two peptides to induce cardiovascular effects using isolated perfused beating rat atria and a cardiac hypertrophied rat model. ANG-(1–7) (0.01, 0.1, and 1 μM) increased ANP secretion and ANP concentration in a dose-dependent manner at high atrial pacing (6.0 Hz) with increased cGMP production. However, at low atrial pacing (1.2 Hz), ANG-(1–7) did not cause changes in atrial parameters. Pretreatment with an antagonist of the Mas receptor or with inhibitors of phosphatidylinositol 3-kinase (PI3K), protein kinase B (Akt), or nitric oxide synthase blocked the augmentation of high atrial pacing-induced ANP secretion by ANG-(1–7). A similar result was observed with the inhibition of the Na+/H+exchanger-1 and Ca2+/calmodulin-dependent kinase II (CaMKII). ANG-(1–7) did not show basal intracellular Ca2+signaling in quiescent atrial myocytes. In an in vivo study using an isoproterenol-induced cardiac hypertrophy animal model, an acute infusion of ANG-(1–7) increased the plasma concentration of ANP by twofold without changes in blood pressure and heart rate. A chronic administration of ANG-(1–7) increased the plasma ANP level and attenuated isoproterenol-induced cardiac hypertrophy. The antihypertrophic effect was abrogated by a cotreatment with the natriuretic peptide receptor-A antagonist. These results suggest that 1) ANG-(1–7) increased ANP secretion at high atrial pacing via the Mas/PI3K/Akt pathway and the activation of Na+/H+exchanger-1 and CaMKII and 2) ANG-(1–7) decreased cardiac hypertrophy which might be mediated by ANP.
Inhibition of VEGF- and NO-dependent angiogenesis does not impair liver regeneration
Authors: Shergill U. , Das A. , Langer D. , Adluri RS. , Maulik N. , Shah V. H.
Published: March 2010

Angiogenesis occurs through a convergence of diverse signaling mechanisms with prominent pathways that include autocrine effects of endothelial nitric oxide (NO) synthase (eNOS)-derived NO and vascular endothelial growth factor (VEGF). However, the redundant and distinct roles of NO and VEGF in angiogenesis remain incompletely defined. Here, we use the partial hepatectomy model in mice genetically deficient in eNOS to ascertain the influence of eNOS-derived NO on the angiogenesis that accompanies liver regeneration. While sinusoidal endothelial cell (SEC) eNOS promotes angiogenesis in vitro, surprisingly the absence of eNOS did not influence the angiogenesis that occurs after partial hepatectomy in vivo. While this observation could not be attributed to induction of alternate NOS isoforms, it was associated with induction of VEGF signaling as evidenced by enhanced levels of VEGF ligand in regenerating livers from mice genetically deficient in eNOS. However, surprisingly, mice that were genetically heterozygous for deficiency in the VEGF receptor, fetal liver kinase-1, also maintained unimpaired capacity for liver regeneration. In summary, inhibition of VEGF- and NO-dependent angiogenesis does not impair liver regeneration, indicating signaling redundancies that allow liver regeneration to continue in the absence of this canonical vascular pathway.
Effect of paricalcitol and cinacalcet on serum phosphate, FGF-23, and bone in rats with chronic kidney disease
Authors: Finch Jane L. , Tokumoto Masanori , Nakamura Hironori , Yao Wei , Shahnazari Mohammad , Lane Nancy , Slatopolsky Eduardo
Published: March 2010

Calcimimetics activate the calcium-sensing receptor (CaR) and reduce parathyroid hormone (PTH) by increasing the sensitivity of the parathyroid CaR to ambient calcium. The calcimimetic, cinacalcet, is effective in treating secondary hyperparathyroidism in dialysis patients [chronic kidney disease (CKD 5)], but little is known about its effects on stage 3–4 CKD patients. We compared cinacalcet and paricalcitol in uremic rats with creatinine clearances “equivalent” to patients with CKD 3–4. Uremia was induced in anesthetized rats using the 5/6th nephrectomy model. Groups were 1) uremic control, 2) uremic + cinacalcet (U+Cin; 15 mg·kg−1·day−1po for 6 wk), 3) uremic + paricalcitol (U+Par; 0.16 μg/kg, 3 × wk, ip for 6 wk), and 4) normal. Unlike U+Par animals, cinacalcet promoted hypocalcemia and marked hyperphosphatemia. The Ca × P in U+Cin rats was twice that of U+Par rats. Both compounds suppressed PTH. Serum 1,25-(OH)2D3was decreased in both U+Par and U+Cin rats. Serum FGF-23 was increased in U+Par but not in U+Cin, where it tended to decrease. Analysis of tibiae showed that U+Cin, but not U+Par, rats had reduced bone volume. U+Cin rats had similar bone formation and reduced osteoid surface, but higher bone resorption. Hypocalcemia, hyperphosphatemia, low 1,25-(OH)2D3, and cinacalcet itself may play a role in the detrimental effects on bone seen in U+Cin rats. This requires further investigation. In conclusion, due to its effects on bone and to the hypocalcemia and severe hyperphosphatemia it induces, we believe that cinacalcet should not be used in patients with CKD without further detailed studies.
Crystal structure of silver metagermanate, Ag2GeO3
Authors: Kurachi Hirokazu , Iwata Tomoyuki , Ouyang Shuxin , Ye Jinhua , Fukuda Koichiro
Published: March 2010

The crystal structure of Ag2GeO3was determined from laboratory X-ray powder diffraction data (CuKα1) using the Rietveld method. The title compound is orthorhombic with space groupP212121,Z=4, unit-cell dimensionsa=0.463 09(1) nm,b=0.713 93(2) nm, andc=1.040 79(3) nm, andV=0.344 10(2) nm3. The final reliability indices wereRwp=5.58%,S=1.26,Rp=4.20%,RB=0.67% , andRF=0.35% . The GeO4tetrahedra form infinite chains of [Ge2O6] along theaaxis, with two tetrahedra per identity period of 0.463 nm. Individual chains are connected by Ag atoms, one-half of which are almost linearly coordinated by two O atoms and the rest are coordinated by three O atoms. The relatively short Ag-Ag distances of 0.299 to 0.339 nm indicate Ag(I)-Ag(I) interaction. This compound is isostructural with Ag2SiO3.
Lattice parameters and orthorhombic distortion of CaMnO3
Authors: Paszkowicz Wojciech , Piętosa Jarosław , Woodley Scott M. , Dłużewski Piotr A. , Kozłowski Mirosław , Martin Christine
Published: March 2010

CaMnO3is a parent compound for numerous multicomponent manganese perovskite oxides. Its crystallographic data are of primary importance in the science and technology of functional CaMnO3-based materials. In the present study, data were collected for a CaMnO3sample at 302 K. The crystal structure refinement yields accurate absolute values of lattice parameters,a=5.281 59(4) Å,b=7.457 30(4) Å, andc=5.267 48(4) Å, leading to orthorhombic distortion of (c/a, √2c/b)=(0.997 33,0.998 95). The orthorhombic distortion of the CaMnO3structure is discussed on the basis of comparison of our unit-cell size with data already published. At a graphical representation of the distortion, it is observed that there is a considerable scatter of the distortion values among the literature data but, interestingly, a considerable fraction of experimental results (including the present one) for stoichiometric samples are grouped around the distortion (c/a, √2c/b)=(0.9973,0.9990), which lies close to a maximum in the extent of orthorhombicity. The influence of off-stoichiometry on the orthorhombic distortion is discussed on the basis of available experimental data. Simulations, employing a mean-field approach for low temperatures, predict an increase in cell volume and structural distortions with the concentration of oxygen vacancies when the additional electrons are localized on the manganese. A simple model of delocalization produced the opposite effect, which is expected to combine with lattice vibrations to recover the cubic phase at high temperatures.
UPFC Location and Performance Analysis in Deregulated Power Systems
Authors: Taher Seyed Abbas , Abrishami Ali Akbar
Published: February 2010

We deal with the effect of Unified Power Flow Controller (UPFC) installation on the objective function of an electricity market. Also this paper proposes a Novel UPFC modelling in OPF which facilities the consideration of the impact of four factors on power market. These include the series transformer impedance addition, the shunt reactive power injection, the in‐phase component of the series voltage and the quadrature component of the series voltage. The impact of each factor on the electricity market objective function is measured and then compared with the results from a sensitivity approach. The proposed sensitivity approach is fast so it does not need to repeat OPF solutions. The total impacts of the factors are used to offer UPFC insertion candidate points. It is shown that there is a clear match between the candidate points of the sensitivity method and those proposed by the introduced UPFC modelling in our test case. Furthermore, based on the proposed method, the relation between settings of UPFC series part and active and reactive power spot prices is presented.
Tolerance Intervals in a Heteroscedastic Linear Regression Context with Applications to Aerospace Equipment Surveillance
Authors: Myhre Janet , Jeske Daniel R. , Rennie Michael , Bi Yingtao
Published: February 2010

A heteroscedastic linear regression model is developed from plausible assumptions that describe the time evolution of performance metrics for equipment. The inherited motivation for the related weighted least squares analysis of the model is an essential and attractive selling point to engineers with interest in equipment surveillance methodologies. A simple test for the significance of the heteroscedasticity suggested by a data set is derived and a simulation study is used to evaluate the power of the test and compare it with several other applicable tests that were designed under different contexts. Tolerance intervals within the context of the model are derived, thus generalizing well-known tolerance intervals for ordinary least squares regression. Use of the model and its associated analyses is illustrated with an aerospace application where hundreds of electronic components are continuously monitored by an automated system that flags components that are suspected of unusual degradation patterns.
Effect of Elevated Carbon Dioxide on Two Scleractinian Corals:Porites cylindrica(Dana, 1846) andGalaxea fascicularis(Linnaeus, 1767)
Authors: Hii Yii-Siang , Ambok Bolong Abol Munafi , Yang Teng-Teng , Liew Hock-Chark
Published: February 2010

This study reveals the effect of elevatedpCO2onPorites cylindricaandGalaxea fascicularis. The corals responded differently under elevatedpCO2. Zooxanthellae cell density, cell mitotic index, and photosynthesis rate ofP. cylindricadecreased drastically under the elevatedpCO2. At the end of the experiment,P. cylindricasuffered from a declining calcium carbonate precipitation rate.G. fascicularisincreased its respiration rate and expelled 71% of its symbiotic zooxanthellae algae under elevatedpCO2. Photosynthetic pigments in the remaining zooxanthellae algae increased from 1.85 to 11.5 times to sustain its photosynthetic outputs. At the end of the experiment,G. fascicularismanaged to increase the rate of its calcium carbonate precipitation. IncreasepCO2in the atmosphere may affect species diversity of coral reefs.
Optical Properties of Blue Phosphor
Authors: Derbal Mourad , Guerbous Lakhdar , Djamel Ouadjaout , Jean Pierre Chaminade , Kadi-Hanifi Mohyddine
Published: February 2010

(, 0.5, 1, 5, and 10 at.%) polycrystalline powders blue phosphors were prepared via the classical solid-state reaction method. X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation, and emission spectra were used to characterize phosphors. By analyzing the excitation and emission spectra of samples, the result indicates that there exists the energy transfer only from the group to the energy level of ion. On the other hand, the influence of the thulium concentration on the blue emission transition and and the emission of group are investigated.
Reaction Diffusion and Chemotaxis for Decentralized Gathering on FPGAs
Authors: Girau Bernard , Torres-Huitzil César , Vlassopoulos Nikolaos , Barrón-Zambrano José Hugo
Published: February 2010

We consider here the feasibility of gathering multiple computational resources by means of decentralized and simple local rules. We study such decentralized gathering by means of a stochastic model inspired from biology: the aggregation of the Dictyostelium discoideum cellular slime mold. The environment transmits information according to a reaction‐diffusion mechanism and the agents move by following excitation fronts. Despite its simplicity this model exhibits interesting properties of self‐organization and robustness to obstacles. We first describe the FPGA implementation of the environment alone, to perform large scale
and rapid simulations of the complex dynamics of this reaction‐diffusion model. Then we describe the FPGA implementation of the environment together with the agents, to study the major challenges that must be solved when designing a fast embedded implementation of the decentralized gathering model. We analyze the results according to the different goals of these hardware implementations.
Glomus Tumor of the Stomach: Depiction by Multidetector CT and Three-Dimensional Volume Rendering Imaging
Authors: Patel Tarak H. , Horton Karen M. , Hruban Ralph H. , Fishman Elliot K.
Published: March 2010

Glomus tumors are uncommon tumors which can occur anywhere within the gastrointestinal tract but have been shown to occur most commonly in the gastric antrum. On CT, these tumors demonstrate hyperenhancement which may help distinguish them from other gastric masses.
Intercell Interference Coordination through Limited Feedback
Authors: Liu Lingjia , Zhang Jianzhong (Charlie) , Yu Jae-Chon , Lee Juho
Published: March 2010

We consider the applications of multicell transmission schemes to the downlink of future wireless communication networks. A multicell multiple-input multiple output-(MIMOs) based scheme with limited coordination among neighboring base stations (BSs) is proposed to effectively combat the intercell interference by taking advantage of the degreesoffreedom in the spatial domain. In this scheme, mobile users are required to feedback channel-related information to both serving base station and interfering base station. Furthermore, a chordal distance-based compression scheme is introduced to reduce the feedback overhead. The performance of the proposed scheme is investigated through theoretical analysis as well as system level simulations. Both results suggest that the so-called “intercell interference coordination through limited feedback” scheme is a very good candidate for improving the cell-edge user throughput as well as the average cell throughput of the future wireless communication networks.
Dietary Glycemic Index, Dietary Glycemic Load, Blood Lipids, and Coronary Heart Disease
Authors: Denova-Gutiérrez Edgar , Huitrón-Bravo Gerardo , Talavera Juan O. , Castañón Susana , Gallegos-Carrillo Katia , Flores Yvonne , Salmerón Jorge
Published: February 2010

Objective. To examine the associations of dietary glycemic index (GI) and dietary glycemic load (GL) with blood lipid concentrations and coronary heart disease (CHD) in nondiabetic participants in the Health Worker Cohort Study (HWCS).Materials and Methods. A cross-sectional analysis was performed, using data from adults who participated in the HWCS baseline assessment. We collected information on participants' socio-demographic conditions, dietary patterns and physical activity via self-administered questionnaires. Dietary GI and dietary GL were measured using a validated food frequency questionnaire. Anthropometric and clinical measurements were assessed with standardized procedures. CHD risk was estimated according to the sex-specific Framingham prediction algorithms.Results. IIn the 5,830 individuals aged 20 to 70 who were evaluated, dietary GI and GL were significantly associated with HDL-C, LDL-C, LDL-C/HDL-C ratio, and triglycerides serum levels. Subjects with high dietary GI have a relative risk of 1.56 (CI 95%; 1.13–2.14), and those with high dietary GL have a relative risk of 2.64 (CI 95%; 1.15–6.58) of having an elevated CHD risk than those who had low dietary GI and GL.Conclusions. Our results suggest that high dietary GI and dietary GL could have an unfavorable effect on serum lipid levels, which are in turn associated with a higher CHD risk.
Pericardial Tamponade in a Patient with Inactive Ulcerative Colitis
Authors: Rezaie Ali , Wong Karen , Gyenes Gabor
Published: February 2010

Cardiac tamponade is a rare extraintestinal manifestation of ulcerative colitis. We present a case report of tamponade occurring four years after curative proctocolectomy and in the absence of any medical therapy for ulcerative colitis. Options for medical management of this condition are also discussed.