bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effects of Freestream Turbulence, Turbulence Length Scale, and Exit Reynolds Number on Turbine Blade Heat Transfer in a Transonic Cascade
Authors: Carullo J. S. , Nasir S. , Cress R. D. , Ng W. F. , Thole K. A. , Zhang L. J. , Moon H. K.
Published: September 2010

This paper experimentally investigates the effect of high freestream turbulence intensity, turbulence length scale, and exit Reynolds number on the surface heat transfer distribution of a turbine blade at realistic engine Mach numbers. Passive turbulence grids were used to generate freestream turbulence levels of 2%, 12%, and 14% at the cascade inlet. The turbulence grids produced length scales normalized by the blade pitches of 0.02, 0.26, and 0.41, respectively. Surface heat transfer measurements were made at the midspan of the blade using thin film gauges. Experiments were performed at the exit Mach numbers of 0.55, 0.78, and 1.03, which represent flow conditions below, near, and above nominal conditions. The exit Mach numbers tested correspond to exit Reynolds numbers of 6×105, 8×105, and 11×105, based on true chord. The experimental results showed that the high freestream turbulence augmented the heat transfer on both the pressure and suction sides of the blade as compared with the low freestream turbulence case. At nominal conditions, exit Mach 0.78, average heat transfer augmentations of 23% and 35% were observed on the pressure side and suction side of the blade, respectively.
Shock Wave Propagation and Spallation Study in Laser Shock Peening
Authors: Cao Yunfeng , Shin Yung C.
Published: September 2010

This paper deals with the spallation induced by shock wave propagation in targets during the laser shock peening process. Physical aspects concerning laser-matter interaction, shock wave propagation, and spallation are considered. A continuous kinetic model for the spallation process is included in a one-dimensional finite-difference hydrodynamic code using Lagrangian coordinates in order to calculate the laser-induced spallation phenomena. Shock wave propagation in solids is calculated and validated by experimental data. The spallation zone location is then calculated for various materials with different thickness of foils and various laser shock peening parameters. The numerical simulations are compared with previously reported experimental results and good agreement is obtained for the spallation threshold and damage zone location.
A Film-Cooling Correlation for Shaped Holes on a Flat-Plate Surface
Authors: Colban Will F. , Thole Karen A. , Bogard David
Published: September 2010

A common method of optimizing coolant performance in gas turbine engines is through the use of shaped film-cooling holes. Despite widespread use of shaped holes, existing correlations for predicting performance are limited to narrow ranges of parameters. This study extends the prediction capability for shaped holes through the development of a physics-based empirical correlation for predicting laterally averaged film-cooling effectiveness on a flat-plate downstream of a row of shaped film-cooling holes. Existing data were used to determine the physical relationship between film-cooling effectiveness and several parameters, including blowing ratio, hole coverage ratio, area ratio, and hole spacing. Those relationships were then incorporated into the skeleton form of an empirical correlation, using results from the literature to determine coefficients for the correlation. Predictions from the current correlation, as well as existing shaped-hole correlations and a cylindrical hole correlation, were compared with the existing experimental data. Results show that the current physics-based correlation yields a significant improvement in predictive capability, by expanding the valid parameter range and improving agreement with experimental data. Particularly significant is the inclusion of higher blowing ratio conditions (up to M=2.5) into the current correlation, whereas the existing correlations worked adequately only at lower blowing ratios (M≈0.5).
Influence of the oxidation conditions on the structural characteristics and optical properties of zinc oxide thin films
Authors: Rambu A. P. , Sirbu D. , Rusu G. I.
Published: September 2010

ZnO thin films were obtained by two-step oxidation processes of Zn films: heating up to 575 K for 1–2 h followed by heating at higher temperature (775 K) for 1 h. Zinc thin films (d=450 nm) were deposited by the quasiclosed volume technique under vacuum onto glass substrates maintained at room temperature. The investigation of film structure, performed by x-ray diffraction technique, corroborated with atomic force microscopy, confirmed that as-prepared zinc films are polycrystalline. The as-prepared ZnO films have a polycrystalline wurtzite (hexagonal) structure, with film crystallites preferentially oriented with (002) planes parallel to the substrate. Transmission and absorption spectra were recorded in the spectral domain from 300 to 1400 nm. The energy band gap for respective films determined from absorption spectra ranged between 3.02 and 3.06 eV.
Empirical beam hardening correction (EBHC) for CT
Authors: Kyriakou Yiannis , Meyer Esther , Prell Daniel , Kachelrieß Marc
Published: September 2010

Purpose:

Due to x‐ray beam polychromaticity and scattered radiation, attenuation measurements tend to be underestimated. Cupping and beam hardening artifacts become apparent in the reconstructed CT images. If only one material such as water, for example, is present, these artifacts can be reduced by precorrecting the rawdata. Higher order beam hardening artifacts, as they result when a mixture of materials such as water and bone, or water and bone and iodine is present, require an iterative beam hardening correction where the image is segmented into different materials and those are forward projected to obtain new rawdata. Typically, the forward projection must correctly model the beam polychromaticity and account for all physical effects, including the energy dependence of the assumed materials in the patient, the detector response, and others. We propose a new algorithm that does not require any knowledge about spectra or attenuation coefficients and that does not need to be calibrated. The proposed method corrects beam hardening in single energy CT data.

Methods:

The onlya priori knowledge entering EBHC is the segmentation of the object into different materials. Materials other than water are segmented from the original image, e.g., by using simple thresholding. Then, a (monochromatic) forward projection of these other materials is performed. The measured rawdata and the forward projected material‐specific rawdata are monomially combined (e.g., multiplied or squared) and reconstructed to yield a set of correction volumes. These are then linearly combined and added to the original volume. The combination weights are determined to maximize the flatness of the new and corrected volume. EBHC is evaluated using data acquired with a modern cone‐beam dual‐source spiral CT scanner (Somatom Definition Flash, Siemens Healthcare, Forchheim, Germany), with a modern dual‐source micro‐CT scanner (TomoScope Synergy Twin, CT Imaging GmbH, Erlangen, Germany), and with a modern C‐arm CT scanner (Axiom Artis dTA, Siemens Healthcare, Forchheim, Germany). A large variety of phantom, small animal, and patient data were used to demonstrate the data and system independence of EBHC.

Results:

Although no physics apart from the initial segmentation procedure enter the correction process, beam hardening artifacts were significantly reduced by EBHC. The image quality for clinical CT, micro‐CT, and C‐arm CT was highly improved. Only in the case of C‐arm CT, where high scatter levels and calibration errors occur, the relative improvement was smaller.

Conclusions:

The empirical beam hardening correction is an interesting alternative to conventional iterative higher order beam hardening correction algorithms. It does not tend to over‐ or undercorrect the data. Apart from the segmentation step, EBHC does not require assumptions on the spectra or on the type of material involved. Potentially, it can therefore be applied to any CT image.
Differentiation between diamagnetic and paramagnetic cerebral lesions based on magnetic susceptibility mapping
Authors: Schweser Ferdinand , Deistung Andreas , Lehr Berengar W. , Reichenbach Jürgen R.
Published: September 2010

Purpose:

Identification of calcifications and hemorrhages is essential for the etiological diagnosis of cerebral lesions. The purpose of this work was to develop a robust method for characterization of para‐ and diamagnetic intracerebral lesions based on clinical gradient‐echo magnetic resonance phase data acquired at 1.5 Tesla.

Methods:

The magnetic susceptibility distribution of biological tissue produces a distinct magnetic field pattern, which is directly reflected in gradient‐echo magnetic resonance phase images. Compared to brain parenchyma, iron‐laden tissues are more paramagnetic, whereas mineralized tissues usually possess more diamagnetic susceptibilities. Magnetic resonance phase data were inverted to the underlying susceptibility distribution utilizing additional geometrical information about the lesions, which was obtained from the gradient‐echo magnitude signal void corresponding to the lesions. Clinical magnetic resonance exams of three patients with multiple brain lesions (total ) were processed and evaluated. For one patient, the results were validated by an additionally available computed tomography scan. Numerical simulations were conducted to evaluate the robustness of the method.

Results:

The obtained susceptibility maps showed impressive delineation of lesions, vessels, and potentially iron‐laden tissue. Compensation of the nonlocal field perturbations was clearly discernable on the susceptibility maps. In all cases, discrimination of para‐ from diamagnetic lesions was achieved and the results were confirmed by the additional computed tomography. The numerical simulations demonstrated that robust determination of the total magnetic moment of lesions is possible. Thus, the proposed method is able to yield quantitative values for the minimum magnetic susceptibility of lesions.

Conclusions:

A method has been developed for noninvasive, semiautomatic characterization of brain lesions based on magnetic resonance imaging data. Initial clinical results demonstrated that the proposed technique can be applied to diagnosis of lesions with calcifications or hemorrhages. If confirmed by larger studies, it bears the potential to obviate the need for confirmation with computed tomography.
A new method to combine 3D reconstruction volumes for multiple parallel circular cone beam orbits
Authors: Baek Jongduk , Pelc Norbert J.
Published: September 2010

Purpose:

This article presents a new reconstruction method for 3D imaging using a multiple 360° circular orbit cone beam CT system, specifically a way to combine 3D volumes reconstructed with each orbit. The main goal is to improve the noise performance in the combined image while avoiding cone beam artifacts.

Methods:

The cone beam projection data of each orbit are reconstructed using the FDK algorithm. When at least a portion of the total volume can be reconstructed by more than one source, the proposed combination method combines these overlap regions using weighted averaging in frequency space. The local exactness and the noise performance of the combination method were tested with computer simulations of a Defrise phantom, aFORBILD head phantom, and uniform noise in the raw data.

Results:

A noiseless simulation showed that the local exactness of the reconstructed volume from the source with the smallest tilt angle was preserved in the combined image. A noise simulation demonstrated that the combination method improved the noise performance compared to a single orbit reconstruction.

Conclusions:

In CT systems which have overlap volumes that can be reconstructed with data from more than one orbit and in which the spatial frequency content of each reconstruction can be calculated, the proposed method offers improved noise performance while keeping the local exactness of data from the source with the smallest tilt angle.
Measuring output factors of small fields formed by collimator jaws and multileaf collimator using plastic scintillation detectors
Authors: Klein David M. , Tailor Ramesh C. , Archambault Louis , Wang Lilie , Therriault‐Proulx Francois , Beddar A. Sam
Published: September 2010

Purpose:

As the practice of using high‐energy photon beams to create therapeutic radiation fields of subcentimeter dimensions (as in intensity‐modulated radiotherapy or stereotactic radiosurgery) grows, so too does the need for accurate verification of beam output at these small fields in which standard practices of dose verification break down. This study investigates small‐field output factors measured using a small plastic scintillation detector (PSD), as well as aionization chamber. Specifically, output factors were measured with both detectors using small fields that were defined by either the X‐Y collimator jaws or the multileaf collimator (MLC).

Methods:

A PSD of 0.5 mm diameter and 2 mm length was irradiated with 6 and 18 MV linac beams. The PSD was positioned vertically at a source‐to‐axis distance of 100 cm, at 10 cm depth in a water phantom, and irradiated with fields ranging in size fromto. The field sizes were defined either by the collimator jaws alone or by a MLC alone. The MLC fields were constructed in two ways: with the closed leaves (i.e., those leaves that were not opened to define the square field) meeting at either the field center line or at a 4 cm offset from the center line. Scintillation light was recorded using a CCD camera and an estimation of error in the median‐filtered signals was made using the bootstrapping technique. Measurements were made using a CC01 ionization chamber under conditions identical to those used for the PSD.

Results:

Output factors measured by the PSD showed close agreement with those measured using the ionization chamber for field sizes ofand above. At smaller field sizes, the PSD obtained output factors as much as 15% higher than those found using the ionization chamber byjaw‐defined fields. Output factors measured with no offset of the closed MLC leaves were as much as 20% higher than those measured using a 4 cm leaf offset.

Conclusions:

The authors’ results suggest that PSDs provide a useful and possibly superior alternative to existing dosimetry systems for small fields, as they are inherently less susceptible to volume‐averaging and perturbation effects than larger, air‐filled ionization chambers. Therefore, PSDs may provide more accurate small‐field output factor determination, regardless of the collimation mechanism.
Hyperpolarized MRS surface coil: Design and signal‐to‐noise ratio estimation
Authors: Giovannetti Giulio , Frijia Francesca , Menichetti Luca , Milanesi Matteo , Ardenkjaer‐Larsen Jan Henrik , De Marchi Daniele , Hartwig Valentina , Positano Vincenzo , Landini Luigi , Lombardi Massimo , Santarelli Maria Filomena
Published: September 2010

Purpose:

Hyperpolarized carbon‐13 magnetic resonance spectroscopy is a novel and powerful tool for exploring the metabolic state of tissue, but a number of technological problems still limit this technology and need innovative solutions. In particular, the low molar concentration of derivate metabolites give rise to low signal‐to‐noise ratio (SNR), which makes the design and development of dedicated RF coils a task of fundamental importance. In this article, the authors describe the simulation and the design of a dedicated surface coil for cardiac metabolism assessment in pig models.

Methods:

A SNR model for a circular loop is presented and applied to the design of a coil which guarantees the desired field‐of‐view and provides high SNR with a good penetration in deep sample regions. The coil resistance was calculated from Ohm's law and the magnetic field pattern was calculated using Biot–Savart law, while the sample induced resistance was calculated using a numerical finite‐difference time‐domain algorithm. Successively, a prototype of the coil was built and tested on the workbench and by acquisition of MR data.

Results:

The comparison of SNR‐vs‐depth profiles between the theoretical SNR model and the experimental SNR extracted from the phantom chemical shift image (CSI) showed the accuracy of the authors’ model. Moreover, the authors demonstrated the use of the coil for the acquisition of a CSI of a hyperpolarized pyruvate phantom.

Conclusions:

The results demonstrated the design trade‐offs to successfully design a dedicated coil for cardiac imaging in the pig with hyperpolarized by developing a SNR model which allows the prediction of the coil performance. This approach can be employed for deriving SNR formulations for coil with more complex geometries.
Coupling Mechanism of a GPCR and a Heterotrimeric G Protein During Chemoattractant Gradient Sensing in
Dictyostelium
Authors: Xu Xuehua , Meckel Tobias , Brzostowski Joseph A. , Yan Jianshe , Meier-Schellersheim Martin , Jin Tian
Published: September 2010

Imaging analyses and computer simulations suggest that a GPCR and its G protein associate only in the presence of ligand.
Shedding Light on FoxO Function
Authors: Adler Elizabeth M.
Published: September 2010

Vitamin D acts through its nuclear receptor to regulate FoxO function.
NF-κB Needs PPARγ
Authors: Gough Nancy R.
Published: September 2010

Unliganded PPARγ is proinflammatory, whereas agonist-bound PPARγ is anti-inflammatory.
Why Cell Signaling Is Noisy
Authors: Ray L. Bryan
Published: September 2010

Noise suppression in biochemical circuits comes at an extreme cost.
Down with TRPV4
Authors: Gough Nancy R.
Published: September 2010

β-arrestin connects stimulation of a G protein–coupled receptor to down-regulation of an ion channel.
Innervation for Branching
Authors: VanHook Annalisa M.
Published: September 2010

Neuronal input is required for maintenance of epithelial progenitor cells in the mouse salivary gland.
α-Synuclein and Aging
Authors: Hurtley Stella M.
Published: September 2010

A protein implicated in neurodegeneration promotes the assembly of membrane fusion complexes.
EASY-HIT: HIV Full-Replication Technology for Broad Discovery of Multiple Classes of HIV Inhibitors
Authors: Kremb Stephan , Helfer Markus , Heller Werner , Hoffmann Dieter , Wolff Horst , Kleinschmidt Andrea , Cepok Sabine , Hemmer Bernhard , Durner Jörg , Brack-Werner Ruth
Published: September 2010

HIV replication assays are important tools for HIV drug discovery efforts. Here, we present a full HIV replication system (EASY-HIT) for the identification and analysis of HIV inhibitors. This technology is based on adherently growing HIV-susceptible cells, with a stable fluorescent reporter gene activated by HIV Tat and Rev. A fluorescence-based assay was designed that measures HIV infection by two parameters relating to the early and the late phases of HIV replication, respectively. Validation of the assay with a panel of nine reference inhibitors yielded effective inhibitory concentrations consistent with published data and allowed discrimination between inhibitors of early and late phases of HIV replication. Finer resolution of the effects of reference drugs on different steps of HIV replication was achieved in secondary time-of-addition assays. The EASY-HIT assay yielded high
Z
′ scores (>0.9) and signal stabilities, confirming its robustness. Screening of the LOPAC
1280
library identified 10 compounds (0.8%), of which eight were known to inhibit HIV, validating the suitability of this assay for screening applications. Studies evaluating anti-HIV activities of natural products with the EASY-HIT technology led to the identification of three novel inhibitory compounds that apparently act at different steps of HIV-1 replication. Furthermore, we demonstrate successful evaluation of plant extracts for HIV-inhibitory activities, suggesting application of this technology for the surveillance of biological extracts with anti-HIV activities. We conclude that the EASY-HIT technology is a versatile tool for the discovery and characterization of HIV inhibitors.
Outbreak of Meropenem-ResistantSerratia marcescensComediated by Chromosomal AmpC β-Lactamase Overproduction and Outer Membrane Protein Loss
Authors: Suh Borum , Bae Il Kwon , Kim Juwon , Jeong Seok Hoon , Yong Dongeun , Lee Kyungwon
Published: September 2010

The aim of this study was to investigate the mechanisms involved in the meropenem resistance ofSerratia marcescensclinical isolates. Meropenem-resistant (MIC range, 16 to 32 μg/ml)S. marcescensisolates were recovered from nine patients in a tertiary hospital in Seoul, South Korea, from June to November 2005. All the isolates shared identical or similar (>85% similarity) SpeI macrorestriction patterns, indicating clonal spread. PCR experiments did not detect any carbapenemase in those isolates. They carried theblaCTX-M-22gene located on a 150-kbp plasmid of the incompatibility group L/M; however, the addition of clavulanic acid exhibited few effects on meropenem MICs. Although meropenem MICs were reduced 4- to 16-fold with the addition of boronic acid, no plasmid-borne AmpC β-lactamase gene was detected in PCR experiments. Real-time quantitative PCR experiments showed that expression levels of the chromosomalampCgene in those isolates were 87.06 to 155.76 times higher than that of the reference strain ATCC 8100. SDS-PAGE showed a lack of the 42-kDa outer membrane protein (OmpF). In combination with the overproduction of the chromosomal AmpC enzyme, the loss of OmpF may have played a role in the acquisition of meropenem resistance in our isolates.
Improved Detection of Mutated Human Cytomegalovirus UL97 by Pyrosequencing
Authors: Schindele Birgit , Apelt Luise , Hofmann Jörg , Nitsche Andreas , Michel Detlef , Voigt Sebastian , Mertens Thomas , Ehlers Bernhard
Published: September 2010

Ganciclovir (GCV) resistance frequently occurs upon prolonged treatment of ongoing active human cytomegalovirus (HCMV) infection in individuals with immature or compromised immune functions (e.g., recipients of solid-organ and hematopoietic stem cell transplants). Using pyrosequencing (PSQ), we established fast and sensitive detection of GCV resistance-associated mutations occurring in the HCMV open reading frame UL97. These mutations have been repeatedly associated with clinical treatment failure. We designed four PSQ assays and evaluated them by analyzing mixtures of plasmids or bacterial artificial chromosome-derived viruses containing UL97 wild-type and mutant sequences. A minimum level of 6% mutant sequence variants could be detected in these mixtures. In order to further evaluate the novel PSQ assays, we tested clinical specimens from patients with active HCMV infections. The results were compared with those obtained by conventional dideoxy chain terminator sequencing. As the PSQ method was more sensitive in detecting minor HCMV mutant fractions in a wild-type population, it is suggested that pyrosequencing is a useful tool for the early detection of emerging GCV-resistant HCMV in GCV-treated patients.
Novel Apramycin Resistance Gene
apmA
in Bovine and Porcine Methicillin-Resistant
Staphylococcus aureus
ST398 Isolates
Authors: Feßler Andrea T. , Kadlec Kristina , Schwarz Stefan
Published: September 2010

A novel apramycin resistance gene,
apmA
, was detected on the ca.-40-kb resistance plasmid pAFS11 from bovine methicillin-resistant
Staphylococcus aureus
(MRSA) of sequence type 398 (ST398). The
apmA
gene coded for a protein of 274 amino acids that was related only distantly to acetyltransferases involved in chloramphenicol or streptogramin A resistance. NsiI deletion of
apmA
resulted in a 16- to 32-fold decrease in the apramycin MICs. An
apmA
-specific PCR identified this gene in one additional bovine and four porcine MRSA ST398 isolates.
How Innate Immune Mechanisms Contribute to Antibody-Enhanced Viral Infections
Authors: Ubol Sukathida , Halstead Scott B.
Published: September 2010

Preexisting antibodies may enhance viral infections. In dengue, nonneutralizing antibodies raised by natural infection with one of four dengue viruses (DENVs) may enhance infection with a different virus by a process we term “intrinsic antibody-dependent enhancement” (iADE). In addition, nonprotective antibodies raised by formalin-inactivated respiratory syncytial virus (RSV) and measles virus vaccines have led to enhanced disease during breakthrough infections. Infections under iADE conditions not only facilitate the process of viral entry into monocytes and macrophages but also modify innate and adaptive intracellular antiviral mechanisms, suppressing type 1 interferon (IFN) production and resulting in enhanced DENV replication. The suppression observedin vitrohas been documented in patients with severe (dengue hemorrhagic fever [DHF]) but not in patient with mild (dengue fever [DF]) secondary dengue virus infections. Important veterinary viral infections also may exhibit iADE. It is thought that use of formalin deconforms viral epitopes of RSV, resulting in poor Toll-like receptor (TLR) stimulation; suboptimal maturation of dendritic cells with reduced production of activation factors CD40, CD80, and CD86; decreased germinal center formation in lymph nodes; and the production of nonprotective antibodies. These antibodies fail to neutralize RSV, allowing replication with secondary stimulation of RSV-primed Th2 cells producing more low-avidity antibody, resulting in immune complexes deposited into affected tissue. However, when formalin-inactivated RSV was administered with a TLR agonist to mice, they were protected against wild-type virus challenge. Safe and effective vaccines against RSV/measles virus and dengue virus may benefit from a better understanding of how innate immune responses can promote production of protective antibodies.
Alternative Endogenous Protein Processing via an Autophagy-Dependent Pathway Compensates forYersinia-Mediated Inhibition of Endosomal Major Histocompatibility Complex Class II Antigen Presentation
Authors: Rüssmann Holger , Panthel Klaus , Köhn Brigitte , Jellbauer Stefan , Winter Sebastian E. , Garbom Sara , Wolf-Watz Hans , Hoffmann Sigrid , Grauling-Halama Silke , Geginat Gernot
Published: September 2010

ExtracellularYersinia pseudotuberculosisemploys a type III secretion system (T3SS) for translocating virulence factors (Yersiniaouter proteins [Yops]) directly into the cytosol of eukaryotic cells. Recently, we used YopE as a carrier molecule for T3SS-dependent secretion and translocation of listeriolysin O (LLO) fromListeria monocytogenes. We demonstrated that translocation of chimeric YopE/LLO into the cytosol of macrophages byYersiniaresults in the induction of a codominant antigen-specific CD4 and CD8 T-cell response in orally immunized mice. In this study, we addressed the requirements for processing and major histocompatibility complex (MHC) class II presentation of chimeric YopE proteins translocated into the cytosol of macrophages by theYersiniaT3SS. Our data demonstrate the ability ofYersiniato counteract exogenous MHC class II antigen presentation of secreted hybrid YopE by the action of wild-type YopE and YopH. In the absence of exogenous MHC class II antigen presentation, an alternative pathway was identified for YopE fusion proteins originating in the cytosol. This endogenous antigen-processing pathway was sensitive to inhibitors of phagolysosomal acidification and macroautophagy, but it did not require the function either of the proteasome or of transporters associated with antigen processing. Thus, by an autophagy-dependent mechanism, macrophages are able to compensate for the YopE/YopH-mediated inhibition of the endosomal MHC class II antigen presentation pathway for exogenous antigens. This is the first report demonstrating that autophagy might enable the host to mount an MHC class II-restricted CD4 T-cell response against translocated bacterial virulence factors. We provide critical new insights into the interaction between the mammalian immune system and a human pathogen.
Transcriptomic and Innate Immune Responses toYersinia pestisin the Lymph Node during Bubonic Plague
Authors: Comer Jason E. , Sturdevant Daniel E. , Carmody Aaron B. , Virtaneva Kimmo , Gardner Donald , Long Dan , Rosenke Rebecca , Porcella Stephen F. , Hinnebusch B. Joseph
Published: September 2010

A delayed inflammatory response is a prominent feature of infection withYersinia pestis, the agent of bubonic and pneumonic plague. Using a rat model of bubonic plague, we examined lymph node histopathology, transcriptome, and extracellular cytokine levels to broadly characterize the kinetics and extent of the host response toY. pestisand how it is influenced by theYersiniavirulence plasmid (pYV). Remarkably, dissemination and multiplication of wild-typeY. pestisduring the bubonic stage of disease did not induce any detectable gene expression or cytokine response by host lymph node cells in the developing bubo. Only after systemic spread had led to terminal septicemic plague was a transcriptomic response detected, which included upregulation of several cytokine, chemokine, and other immune response genes. Although an initial intracellular phase ofY. pestisinfection has been postulated, a Th1-type cytokine response associated with classical activation of macrophages was not observed during the bubonic stage of disease. However, elevated levels of interleukin-17 (IL-17) were present in infected lymph nodes. In the absence of pYV, sustained recruitment to the lymph node of polymorphonuclear leukocytes (PMN, or neutrophils), the major IL-17 effector cells, correlated with clearance of infection. Thus, the ability to counteract a PMN response in the lymph node appears to be a majorin vivofunction of theY. pestisvirulence plasmid.
A 32-Kilodalton Hydrolase Plays an Important Role in
Paracoccidioides brasiliensis
Adherence to Host Cells and Influences Pathogenicity
Authors: Hernández Orville , Almeida Agostinho J. , Gonzalez Angel , Garcia Ana Maria , Tamayo Diana , Cano Luz Elena , Restrepo Angela , McEwen Juan G.
Published: September 2010

One of the most crucial events during infection with the dimorphic fungus
Paracoccidioides brasiliensis
is adhesion to pulmonary epithelial cells, a pivotal step in the establishment of disease. In this study, we have evaluated the relevance of a 32-kDa protein, a putative adhesion member of the haloacid dehalogenase (HAD) superfamily of hydrolases, in the virulence of this fungus. Protein sequence analyses have supported the inclusion of PbHad32p as a hydrolase and have revealed a conserved protein only among fungal dimorphic and filamentous pathogens that are closely phylogenetically related. To evaluate its role during the host-pathogen interaction, we have generated mitotically stable
P. brasiliensis HAD32
(
PbHAD32
) antisense RNA (aRNA) strains with consistently reduced gene expression. Knockdown of
PbHAD32
did not alter cell vitality or viability but induced morphological alterations in yeast cells. Moreover, yeast cells with reduced
PbHAD32
expression were significantly affected in their capacity to adhere to human epithelial cells and presented decreased virulence in a mouse model of infection. These data support the hypothesis that PbHad32p binds to extracellular matrix (ECM) proteins and modulates the initial immune response for evasion of host defenses. Our findings point to
PbHAD32
as a novel virulence factor active during the initial interaction with host cells in
P. brasiliensis
.
Comparison of the Regulation, Metabolic Functions, and Roles in Virulence of the Glyceraldehyde-3-Phosphate Dehydrogenase Homologues
gapA
and
gapB
in
Staphylococcus aureus
Authors: Purves Joanne , Cockayne Alan , Moody Peter C. E. , Morrissey Julie A.
Published: September 2010

The Gram-positive bacterium
Staphylococcus aureus
contains two glyceraldehyde-3-phosphate dehydrogenase (GAPDH) homologues known as GapA and GapB. GapA has been characterized as a functional GAPDH protein, but currently there is no biological evidence for the role of GapB in metabolism in
S. aureus
. In this study we show through a number of complementary methods that
S. aureus
GapA is essential for glycolysis while GapB is essential in gluconeogenesis. These proteins are reciprocally regulated in response to glucose concentrations, and both are influenced by the glycolysis regulator protein GapR, which is the first demonstration of the role of this regulator in
S. aureus
and the first indication that GapR homologues control genes other than those within the glycolytic operon. Furthermore, we show that both GapA and GapB are important in the pathogenesis of
S. aureus
in a
Galleria mellonella
model of infection, showing for the first time in any bacteria that both glycolysis and gluconeogenesis have important roles in virulence.
Reproducible Science
Authors: Casadevall Arturo , Fang Ferric C.
Published: September 2010

The reproducibility of an experimental result is a fundamental assumption in science. Yet, results that are merely confirmatory of previous findings are given low priority and can be difficult to publish. Furthermore, the complex and chaotic nature of biological systems imposes limitations on the replicability of scientific experiments. This essay explores the importance and limits of reproducibility in scientific manuscripts.
Epidemiology of fall related forearm and wrist fractures among adults treated in US hospital emergency departments
Authors: Orces Carlos H , Martinez Fidel J
Published: September 2010

Objective

To examine national estimates of forearm and wrist fractures among adults treated in US emergency departments.

Methods

The National Electronic Injury Surveillance System All Injury Program was used to estimate emergency department visits for unintentional fall related forearm and/or wrist fractures among adults aged 50 years or older between 2001 and 2007. Census population estimates were used as the denominator to calculate age-specific and age-adjusted fracture rates per 100 000 persons.

Results

Based on 14 771 cases, an estimated 1 045 008 adults aged ≥50 years were treated in US hospital emergency departments for fall related forearm and/or wrist fractures during the study period. Of these, an estimated 832 591 (80%) fractures occurred among women. The incidence of fractures among women increased gradually with age from the age of 50 years. In men, fracture rates remained low until later in life. Between 2001 and 2007, fracture rates increased predominantly among women in the age group 50–59 years at an annual rate of 3.9% (95% CI −0.1 to 8.2).

Conclusions

The study indicates marked gender differences in unintentional fall related forearm and/or wrist fractures among adults aged ≥50 years treated in US hospital emergency departments. Interventions aimed at preventing falls might be effective in reducing the incidence of this injury, particularly in those women who already have diminished bone mineral.
A theoretical study of the conformation of meso-tetraphenylporphyrin (TPPH2), its anions, cations and metal complexes (Mg2+, Ca2+ and Zn2+)
Authors: Alkorta Ibon , Elguero José , Silva Artur M. S. , Tomé Augusto C.
Published: September 2010

A theoretical study has been carried out on TPPH2 (both tautomers), its deprotonated and protonated forms, as well as complexes of TPP containing Mg 2+, Ca 2+ and Zn 2+ ions. Two properties have been analyzed. The first one considers the conformation of the meso-phenyl rings and the deformation of the porphyrin macrocycle, the second one relates to the barriers of rotation of the meso-phenyl rings (atropisomerism). In the case of the Zn complex ( ZnTPP ), the coordination effects with the N3 of 1H-imidazole have been calculated.
EFFECT OF HARMONIC IN-PLANE EDGE LOADING ON DYNAMIC STABILITY OF STIFFENED SHELL PANELS WITH CUTOUTS
Authors: PATEL S. N. , DATTA P. K. , SHEIKH A. H.
Published: September 2010

The effect of non-uniform in-plane pulsating edge loading on dynamic instability behavior of perforated stiffened shell panels is presented in this paper using finite element method. The eight-noded isoparametric degenerated shell element and a compatible three-noded curved beam element are used to model the shell panels and the stiffeners, respectively. Bolotin method is applied to analyze the dynamic instability regions. Numerical results of convergence studies are presented and comparison is made with the published results from the literature. The effects of various parameters like shell geometry, loading type, cutout size and dynamic load factors are considered in dynamic instability analysis of stiffened shell panels with cutout. The buckling results of the cutout stiffened panels are also presented.
3D ROCK MASS GEOMETRICAL MODELING WITH ARBITRARY DISCONTINUITIES
Authors: FU GUOYANG , HE LEI , MA GUOWEI
Published: September 2010

This paper describes an algorithm to generate the realistic numerical representation of three-dimensional rock masses. The discontinuities can be treated as infinite or finite planes with or without thickness. A finite plane is represented by a polygon and defined using centroid of the polygon, orientation, geometry in 2D plane, the angle between strike line and reference line and other properties including cohesion, friction angle, tensile strength and aperture. Through 3D discontinuity network simulation, the information of discontinuities is obtained as the input data for block generation. The block generation process includes boundary planes cutting, discontinuities cutting and block integration. The results are also verified by graphical check, topological and geometrical properties of a polyhedron. The algorithm we adopt is convenient to be developed into a computer program. The generated model, in which the blocks and loops of blocks could be convex or concave, can be used for single block stability analysis or block model codes like discrete element method (DEM) and discontinuous deformation analysis (DDA).
Chromitites from the Fiskenæsset anorthositic complex, West Greenland: clues to late Archaean mantle processes
Authors: Rollinson Hugh , Reid Claire , Windley Brian
Published: September 2010

Chromitites in the late Archaean Fiskenæsset anorthosite complex are characterized by a most unusual mineral assemblage: highly calcic plagioclase, iron-rich aluminous chromites and primary amphibole. In particular, the chromite compositions are atypical of chromitites in layered igneous intrusions. However, rare occurrences of this mineral assemblage are found in modern arcs and it is proposed here that the late Archaean calcic anorthositic chromitites formed by the partial melting of unusually aluminous harzburgite in a mantle wedge above a subduction zone. This melting process produced a hydrous, aluminous basalt, which fractionated at depth in the crust to produce a variety of high-alumina basalt compositions, from which the anorthosite complex with its chromitite horizons formed as a cumulate within the continental crust. The principal trigger for the late precipitation of chromite is thought to have been the removal of Al from the basaltic melt through plagioclase crystallization, and the build-up of Cr through an absence of clinopyroxene. It is proposed that the aluminous mantle source of the parent magma was produced by the melting of a harzburgitic mantle refertilized by small-volume, aluminous slab melts. This process ceased at the end of the Archaean because the dominant mechanism of crust generation changed such that melt production shifted from the slab into the mantle wedge, thus explaining why highly calcic anorthosites are almost totally restricted to the Archaean.
Roles of strike-slip faults during continental deformation: examples from the active Arabia–Eurasia collision
Authors: Allen Mark B.
Published: September 2010

This paper concerns the kinematics of active strike-slip faults in the Arabia–Eurasia collision zone, and how they accommodate plate convergence. Several roles are discernible:
(1) collision zone boundaries
, the left-lateral Dead Sea Fault System and right-lateral faults in eastern Iran form the western and eastern boundaries of the collision zone;
(2) tectonic escape structures
, the North and East Anatolian faults transport intervening crust westwards, out of the path of the Arabia;
(3) strain partitioning
, right-lateral slip on the Zagros Main Recent Fault and NW–SE-striking thrusts to its SW produce north–south convergence, parallel to the plate vector; left-lateral slip along the Alborz range and thrusts across it produce oblique left-lateral shortening;
(4) shortening arrays
, arrays of strike-slip faults (e.g. Kopeh Dagh and eastern Iranian faults) rotate about vertical axes, producing north–south shortening without crustal thickening;
(5) transfer zones
, fold trends and earthquake slip vectors change orientation across strike-slip faults in the Zagros, suggesting that these faults allow for changes in thrust transport along strike in the orogen. These different roles emphasize the complex behaviour of continental crust, and the advantages of studying active tectonics rather than ancient examples.
Was Late Cretaceous–Paleocene obduction of ophiolite complexes the primary cause of crustal thickening and regional metamorphism in the Pakistan Himalaya?
Authors: Searle M. P. , Treloar P. J.
Published: September 2010

Regional metamorphic rocks in the Pakistan Himalaya include both UHP coesite eclogite-facies and MP/T kyanite–sillimanite-grade Barrovian metamorphic rocks. Age data show that peak metamorphism of both was
c.
47 Ma.
40
Ar–
39
Ar hornblende cooling ages date post-peak metamorphic cooling of both through 500 °C by 40 Ma, some 20 Ma earlier than for metamorphic rocks in the central and eastern Himalaya. Typically these ages have been explained by obduction of the Kohistan arc onto the Indian plate at about 50 Ma and India–Asia collision. We suggest instead that the earlier metamorphic and cooling ages of the Pakistani Barrovian metamorphic sequence could be partially explained by Late Cretaceous to Early Paleocene crustal thickening linked to obduction of an ophiolite thrust sheet onto the leading edge of the Indian plate, similar to the Spontang Ophiolite in Ladakh. Heating following on from this Paleocene crustal thickening explains peak Barrovian metamorphism within 5–10 Ma of subsequent obduction of Kohistan. Remnants of the ophiolite sheet, and underlying Tethyan sediments, are preserved in NW India and in western Pakistan but not in northern Pakistan. Tectonic erosion removed all cover sequences (including the ophiolites) from the Indian plate basement.
Landscape development of the Himalayan–Tibetan orogen: a review
Authors: Owen Lewis A.
Published: September 2010

The Himalayan–Tibetan orogen provides one of the best natural laboratories in which to examine the nature and dynamics of landscape development within continent–continent collision zones. Many new tectonic–climatic–geomorphological theories and models have emerged and/or have been greatly influenced as a consequence of the study of the region and the quest to understand its geomorphological development. These include models of the interactions between tectonics, climate and surfice processes, notably, the influence of climate on surface uplift by denudational unloading; the limiting of topography by glaciation (the glacial buzz-saw model); localized uplift at syntaxes by enhanced fluvial and glacial erosion that, in turn, weaken the lithosphere, enhancing surface uplift and exhumation (the tectonic aneurysm model); climate-driven out-of-sequence thrusting and crustal channel flow; glacial damming leading to differential erosion and uplift; paraglaciation; and the influence of extreme events such as earthquakes, landslides, and floods as major formative processes. The development of new technologies, including satellite remote sensing and global positioning systems, and analytical methods such as numerical dating is now allowing these theories and models to be tested and will inevitably lead to new paradigms.
The anatomy and ontogeny of modern intra-oceanic arc systems
Authors: Stern Robert J.
Published: September 2010

Intra-oceanic arc systems (IOASs) represent the oceanic endmember of arc–trench systems and have been the most important sites of juvenile continental crust formation for as long as plate tectonics has operated. IOASs' crustal profiles are wedge-shaped, with crust up to 20–35 km thick; a more useful definition is that IOASs occur as chains of small islands, generally just the tops of the largest volcanoes. A very small fraction of IOASs lie above sea level, but advancing marine technologies allow their most important features to be defined. Modern IOASs subduct old, dense oceanic lithosphere and so tend to be under extension. They consist of four parallel components: trench, forearc, volcanic–magmatic arc, and back-arc, occupying a ≥200 km zone along the leading edge of the overriding plate. These components form as a result of hydrous melting of the mantle and reflect the strongly asymmetric nature of subduction processes. Forearcs preserve infant arc lithosphere whereas magmatism in mature IOASs is concentrated along the volcanic–magmatic front. Mature IOASs often have minor rear-arc volcanism and, because most IOASs are strongly extensional, sea-floor spreading often forms back-arc basins. Sub-IOAS mantle is also asymmetric, with serpentinized harzburgite beneath the forearc, pyroxene-rich low-
V
p
mantle beneath the magmatic front, and lherzolite–harzburgite beneath back-arc basins. Because most IOASs are far removed from continents, they subduct oceanic lithosphere with thin sediments and have naked forearcs subject to tectonic erosion. IOASs evolve from broad zones of very high degrees of melting and sea-floor spreading during their first 5–10 Ma, with the volcanic–magmatic front retreating to its ultimate position
c.
200 km from the trench.
The Khanka Block, NE China, and its significance for the evolution of the Central Asian Orogenic Belt and continental accretion
Authors: Wilde Simon A. , Wu Fu-Yuan , Zhao Guochun
Published: September 2010

Sensitive high-resolution ion microprobe and inductively coupled plasma mass spectrometry U–Pb dating of zircons from granitoids and paragneiss in the Chinese segment of the Khanka Block reveals that granite magmatism occurred at 518±7 Ma and was followed shortly after by high-grade metamorphism at
c
. 500 Ma (timing ranging from 491±4 Ma in medium-grained granitoid, through 499±10 Ma in porphyritic granite, to 501±8 Ma in paragneiss). Such a scenario has previously been established on similar lithologies in the Jiamusi Block to the west, with identical ages. This suggests that the Khanka and Jiamusi blocks form part of a single terrane and that the Dunhua–Mishan Fault, which was previously considered to separate two unique terranes, cannot be a terrane boundary fault. Previous suggestions of a link between the Khanka Block and the Hida Block in Japan are not supported following a comparison of the new zircon data with published ages for the Japanese terranes. A granitoid with an age of 112±1 Ma in the Khanka Block probably records the effect of Pacific plate subduction, as such ages are common further south in the extreme eastern part of the North China Craton, where they have been related to post-collisional extension and lithospheric thinning in the Jiaodong Peninsula. The presence of such young granitoids, and the previous dating of blueschist-facies metamorphism as late Early Jurassic in the Heilongjiang Complex of the Jiamusi Block, supports the view that the current location of the Jiamusi–Khanka terrane is a product of circum-Pacific accretion rather than it being a microcontinental block that was trapped by the northward collision of the North China Craton with Siberia as part of the assembly of the main Central Asian Orogenic Belt.