bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetoresistance and magnetocaloric effect at a structural phase transition from a paramagnetic martensitic state to a paramagnetic austenitic state in Ni50Mn36.5In13.5 Heusler alloys
Authors: Pathak Arjun K. , Dubenko Igor , Pueblo Christopher , Stadler Shane , Ali Naushad
Published: April 2010

It is established, using magnetization measurements, that Ni50Mn36.5In13.5 is in a paramagnetic state (PS) above and below the martensitic transition temperature (TM). Magnetoresistance (MR) and magnetic entropy changes (ΔSM) in the vicinity of TM were studied. MR and ΔSM at TM were found to be ≈−8% and ≈+24 J Kg−1 K−1, respectively, at ΔH=5 T. Although MR and ΔSM values were lower than compared to those found in other Heusler systems, the significantly smaller hysteresis observed in Ni50Mn36.5In13.5 makes this compound, and other such compounds that undergo a martensitic transition in a PS, promising for the study and applications of magnetocaloric magnetic materials.
Demographic variability and long-term change in a coral reef sponge along a cross-shelf gradient of the Great Barrier Reef
Authors: Bannister R. J. , Battershill C. N. , de Nys R.
Published: April 2010

Effects of anthropogenic inputs on corals are well documented in regard to the ecology of coral reefs. However, responses to anthropogenic changes by sponge assemblages, also a key component of coral reefs, have received less attention. This paper quantifies differences in abundance, size and distribution of the sponge Rhopaloeides odorabile across a cross-shelf reef system on the central Great Barrier Reef (GBR) from neritic to outer reef oligotrophic waters. Benthic surveys were conducted in reef habitats spatially separated across the continental shelf. The mean abundance of R. odorabile increased significantly with increasing distance from coastal habitats, with 3.5 times more individuals offshore than inshore. In contrast, the mean size (volume) of R. odorabile individuals did not differ significantly across the cross-shelf reef system. On inshore reefs, R. odorabile was restricted to depths <10 m, with a preference for shallower depths (5–6 m). On offshore reefs, R. odorabile was found as deep as 15 m and predominantly between 9 and 10 m. These demographic changes in R. odorabile populations, together with a general population size reduction from surveys made decades prior, suggest a response to anthropogenic impacts across the continental shelf of the central GBR.
Trophic structure of benthic resources and consumers varies across a regulated floodplain wetland
Authors: Kelleway Jeff , Mazumder Debashish , Wilson G. Glenn , Saintilan Neil , Knowles Lisa , Iles Jordan , Kobayashi Tsuyoshi
Published: April 2010

Riverine food webs are often laterally disconnected (i.e. between watercourses) in regulated floodplain wetlands for prolonged periods. We compared the trophic structure of benthic resources and consumers (crustaceans and fish) of the three watercourses in a regulated floodplain wetland (the Gwydir Wetlands, Australia) that shared the same source water but were laterally disconnected. The crustaceans Cherax destructor (yabby), Macrobrachium australiense (freshwater prawn), the exotic fish Cyprinus carpio (European carp) and Carassius auratus (goldfish) showed significantly different δ13C values among the watercourses, suggesting spatial differences in primary carbon sources. Trophic positions were estimated by using δ15N values of benthic organic matter as the base of the food web in each watercourse. The estimated trophic positions and gut contents showed differences in trophic positions and feeding behaviours of consumers between watercourses, in particular for Melanotaenia fluviatilis (Murray–Darling rainbowfish) and M. australiense. Our findings suggest that the observed spatial variation in trophic structure appears to be largely related to the spatial differences in the extent and type of riparian vegetation (i.e. allochthonous carbon source) across the floodplain that most likely constituted part of the benthic resources.
Catadromous migrations by female tupong (Pseudaphritis urvillii) in coastal streams in Victoria, Australia
Authors: Crook David A. , Koster Wayne M. , Macdonald Jed I. , Nicol Simon J. , Belcher Chris A. , Dawson David R. , O'Mahony Damien J. , Lovett Danny , Walker Adam , Bannam Lucas
Published: April 2010

Understanding migratory requirements is critical for the conservation of diadromous fishes. Tupong (Pseudaphritis urvillii) are diadromous fishes found in freshwater and estuarine regions of south-eastern Australia. Previous studies have hypothesised that mature female tupong undertake downstream spawning migrations from freshwater to the estuary or sea, with a compensatory return of juveniles, and possibly spent fish, back upstream. We applied acoustic telemetry to test this hypothesis. We tagged 55 female tupong in two river systems in Victoria, Australia, and tracked movements for 4- to 6-month periods over 2 years. Thirty-one fish undertook rapid downstream migrations and then appeared to move through the estuary and out to sea between May and August in each year. Migration was associated with relatively high river discharges, and movement from the estuary to the sea tended to occur most frequently during intermediate moon phases. Low rates of movement between September and April suggested that tupong inhabited restricted home ranges outside of the spawning season. The apparently disparate migratory patterns of female (catadromous) and male (non-diadromous) tupong are rare amongst fishes globally. Differential exertion of a range of selective pressures may have resulted in the evolution of sexual differences in migratory modes in this species.
Peroxisome proliferator-activated receptor gamma activation is required for maintenance of innate antimicrobial immunity in the colon
Authors: Peyrin-Biroulet Laurent , Beisner Julia , Wang Guoxing , Nuding Sabine , Oommen Sajit Thottathil , Kelly Denise , Parmentier-Decrucq Erika , Dessein Rodrigue , Merour Emilie , Chavatte Philipe , Grandjean Teddy , Bressenot Aude , Desreumaux Pierre , Colombel Jean-Frédéric , Desvergne Béatrice , Stange Eduard F. , Wehkamp Jan , Chamaillard Mathias
Published: April 2010

Crohn's disease (CD), a major form of human inflammatory bowel disease, is characterized by primary immunodeficiencies. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) is essential for intestinal homeostasis in response to both dietary- and microbiota-derived signals. Its role in host defense remains unknown, however. We show that PPARγ functions as an antimicrobial factor by maintaining constitutive epithelial expression of a subset of β-defensin in the colon, which includes mDefB10 in mice and DEFB1 in humans. Colonic mucosa of
Pparγ
mutant animals shows defective killing of several major components of the intestinal microbiota, including
Candida albicans
,
Bacteroides fragilis
,
Enterococcus faecalis
, and
Escherichia coli
. Neutralization of the colicidal activity using an anti-mDefB10 blocking antibody was effective in a PPARγ-dependent manner. A functional promoter variant that is required for DEFB1 expression confers strong protection against Crohn's colitis and ileocolitis (odds ratio, 0.559;
P
= 0.018). Consistently, colonic involvement in CD is specifically linked to reduced expression of DEFB1 independent of inflammation. These findings support the development of PPARγ-targeting therapeutic and/or nutritional approaches to prevent colonic inflammation by restoring antimicrobial immunity in CD.
An ecological valence theory of human color preference
Authors: Palmer Stephen E. , Schloss Karen B.
Published: April 2010

Color preference is an important aspect of visual experience, but little is known about why people in general like some colors more than others. Previous research suggested explanations based on biological adaptations [Hurlbert AC, Ling YL (2007)
Curr Biol
17:623–625] and color-emotions [Ou L-C, Luo MR, Woodcock A, Wright A (2004)
Color Res Appl
29:381–389]. In this article we articulate an ecological valence theory in which color preferences arise from people’s average affective responses to color-associated objects. An empirical test provides strong support for this theory: People like colors strongly associated with objects they like (e.g., blues with clear skies and clean water) and dislike colors strongly associated with objects they dislike (e.g., browns with feces and rotten food). Relative to alternative theories, the ecological valence theory both fits the data better (even with fewer free parameters) and provides a more plausible, comprehensive causal explanation of color preferences.
A thermosensory pathway mediating heat-defense responses
Authors: Nakamura Kazuhiro , Morrison Shaun F.
Published: April 2010

Afferent neural transmission of temperature sensation from skin thermoreceptors to the central thermoregulatory system is important for the defense of body temperature against environmental thermal challenges. Here, we report a thermosensory pathway that triggers physiological heat-defense responses to elevated environmental temperature. Using in vivo electrophysiological and anatomical approaches in the rat, we found that neurons in the dorsal part of the lateral parabrachial nucleus (LPBd) glutamatergically transmit cutaneous warm signals from spinal somatosensory neurons directly to the thermoregulatory command center, the preoptic area (POA). Intriguingly, these LPBd neurons are located adjacent to another group of neurons that mediate cutaneous cool signaling to the POA. Functional experiments revealed that this LPBd–POA warm sensory pathway is required to elicit autonomic heat-defense responses, such as cutaneous vasodilation, to skin-warming challenges. These findings provide a fundamental framework for understanding the neural circuitry maintaining thermal homeostasis, which is critical to survive severe environmental temperatures.
Calcium isotope constraints on the end-Permian mass extinction
Authors: Payne Jonathan L. , Turchyn Alexandra V. , Paytan Adina , DePaolo Donald J. , Lehrmann Daniel J. , Yu Meiyi , Wei Jiayong
Published: April 2010

The end-Permian mass extinction horizon is marked by an abrupt shift in style of carbonate sedimentation and a negative excursion in the carbon isotope (
δ
13
C) composition of carbonate minerals. Several extinction scenarios consistent with these observations have been put forward. Secular variation in the calcium isotope (
δ
44/40
Ca) composition of marine sediments provides a tool for distinguishing among these possibilities and thereby constraining the causes of mass extinction. Here we report
δ
44/40
Ca across the Permian-Triassic boundary from marine limestone in south China. The
δ
44/40
Ca exhibits a transient negative excursion of ∼0.3‰ over a few hundred thousand years or less, which we interpret to reflect a change in the global
δ
44/40
Ca composition of seawater. CO
2
-driven ocean acidification best explains the coincidence of the
δ
44/40
Ca excursion with negative excursions in the
δ
13
C of carbonates and organic matter and the preferential extinction of heavily calcified marine animals. Calcium isotope constraints on carbon cycle calculations suggest that the average
δ
13
C of CO
2
released was heavier than -28‰ and more likely near -15‰; these values indicate a source containing substantial amounts of mantle- or carbonate-derived carbon. Collectively, the results point toward Siberian Trap volcanism as the trigger of mass extinction.
Secretory IgA-mediated protection againstV. choleraeand heat-labile enterotoxin-producing enterotoxigenicEscherichia coliby rice-based vaccine
Authors: Tokuhara Daisuke , Yuki Yoshikazu , Nochi Tomonori , Kodama Toshio , Mejima Mio , Kurokawa Shiho , Takahashi Yuko , Nanno Masanobu , Nakanishi Ushio , Takaiwa Fumio , Honda Takeshi , Kiyono Hiroshi
Published: April 2010

Cholera and enterotoxigenicEscherichia coli(ETEC) are among the most common causes of acute infantile gastroenteritis globally. We previously developed a rice-based vaccine that expressed cholera toxin B subunit (MucoRice-CTB) and had the advantages of being cold chain–free and providing protection against cholera toxin (CT)–induced diarrhea. To advance the development of MucoRice-CTB for human clinical application, we investigated whether the CTB-specific secretory IgA (SIgA) induced by MucoRice-CTB gives longstanding protection against diarrhea induced byVibrio choleraeand heat-labile enterotoxin (LT)–producing ETEC (LT-ETEC) in mice. Oral immunization with MucoRice-CTB stored at room temperature for more than 3 y provided effective SIgA-mediated protection against CT- or LT-induced diarrhea, but the protection was impaired in polymeric Ig receptor–deficient mice lacking SIgA. The vaccine gave longstanding protection against CT- or LT-induced diarrhea (for ≥6 months after primary immunization), and a single booster immunization extended the duration of protective immunity by at least 4 months. Furthermore, MucoRice-CTB vaccination prevented diarrhea in the event ofV. choleraeand LT-ETEC challenges. Thus, MucoRice-CTB is an effective long-term cold chain–free oral vaccine that induces CTB-specific SIgA-mediated longstanding protection againstV. cholerae– or LT-ETEC–induced diarrhea.
Mapping the physical and functional interactions between the tumor suppressors p53 and BRCA2
Authors: Rajagopalan Sridharan , Andreeva Antonina , Rutherford Trevor J. , Fersht Alan R.
Published: April 2010

p53 maintains genome integrity either by regulating the transcription of genes involved in cell cycle, apoptosis, and DNA repair or by interacting with partner proteins. Here we provide evidence for a direct physical interaction between the tumor suppressors p53 and BRCA2. We found that the transactivation domain of p53 made specific interactions with the C-terminal oligonucleotide/oligosaccharide-binding-fold domains of BRCA2 (BRCA2
CTD
). A second distinct site situated on the p53 DNA-binding domain, bound to a region containing BRC repeats of BRCA2 (BRCA2
[BRC1-8]
) and may contribute synergistically for high affinity association of intact full-length proteins. Overexpression of BRCA2 and BRCA2
CTD
suppressed the transcriptional activity of p53 with a concomitant reduction in the expression of p53-target genes such as Bax and p21. Consequently, p53-mediated apoptosis was significantly attenuated by BRCA2. The observed physical association of p53 and BRCA2 may have important functional implications in the p53 transactivation-independent suppression of homologous recombination and suggests a possible interregulatory role for both proteins in apoptosis and DNA repair.
Batf coordinates multiple aspects of B and T cell function required for normal antibody responses
Authors: Betz Briana C. , Jordan-Williams Kimberly L. , Wang Chuanwu , Kang Seung Goo , Liao Juan , Logan Michael R. , Kim Chang H. , Taparowsky Elizabeth J.
Published: April 2010

Batf belongs to the activator protein 1 superfamily of basic leucine zipper transcription factors that includes Fos, Jun, and Atf proteins. Batf is expressed in mouse T and B lymphocytes, although the importance of Batf to the function of these lineages has not been fully investigated. We generated mice (BatfΔZ/ΔZ) in which Batf protein is not produced. BatfΔZ/ΔZ mice contain normal numbers of B cells but show reduced numbers of peripheral CD4+ T cells. Analysis of CD4+ T helper (Th) cell subsets in BatfΔZ/ΔZ mice demonstrated that Batf is required for the development of functional Th type 17 (Th17), Th2, and follicular Th (Tfh) cells. In response to antigen immunization, germinal centers were absent in BatfΔZ/ΔZ mice and the maturation of Ig-secreting B cells was impaired. Although adoptive transfer experiments confirmed that this B cell phenotype can be driven by defects in the BatfΔZ/ΔZ CD4+ T cell compartment, stimulation of BatfΔZ/ΔZ B cells in vitro, or by a T cell–independent antigen in vivo, resulted in proliferation but not class-switch recombination. We conclude that loss of Batf disrupts multiple components of the lymphocyte communication network that are required for a robust immune response.
Finding metabolic pathways using atom tracking
Authors: Heath Allison P. , Bennett George N. , Kavraki Lydia E.
Published: April 2010

Motivation: Finding novel or non-standard metabolic pathways, possibly spanning multiple species, has important applications in fields such as metabolic engineering, metabolic network analysis and metabolic network reconstruction. Traditionally, this has been a manual process, but the large volume of metabolic data now available has created a need for computational tools to automatically identify biologically relevant pathways.

Results: We present new algorithms for finding metabolic pathways, given a desired start and target compound, that conserve a given number of atoms by tracking the movement of atoms through metabolic networks containing thousands of compounds and reactions. First, we describe an algorithm that identifies linear pathways. We then present a new algorithm for finding branched metabolic pathways. Comparisons to known metabolic pathways demonstrate that atom tracking enables our algorithms to avoid many unrealistic connections, often found in previous approaches, and return biologically meaningful pathways. Our results also demonstrate the potential of the algorithms to find novel or non-standard pathways that may span multiple organisms.

Availability: The software is freely available for academic use at: http://www.kavrakilab.org/atommetanet

Contact:  kavraki@rice.edu

Supplementary information:  Supplementary data are available at Bioinformatics online.
Genetic differentiation between eastern and western Mediterranean swordfish revealed by phylogeographic analysis of the mitochondrial DNA control region
Authors: Viñas Jordi , Pérez-Serra Alexandra , Vidal Oriol , Alvarado Bremer Jaime R. , Pla Carles
Published: April 2010

Viñas, J., Pérez-Serra, A., Vidal, O., Alvarado Bremer, J. R., and Pla, C. 2010. Genetic differentiation between eastern and western Mediterranean swordfish revealed by phylogeographic analysis of the mitochondrial DNA control region. – ICES Journal of Marine Science, 67: 1222–1229. Despite there being evidence of several discrete breeding grounds, Mediterranean populations of swordfish have been considered a single panmictic unit with no genetic substructure. Sequence analysis of the mitochondrial DNA (mtDNA) control region of five Mediterranean locations (n = 251) reveals for the first time a clear genetic differentiation between eastern and western Mediterranean populations. This differentiation was detected only after conducting separate phylogeographic analyses on two previously described mtDNA clades. Although the frequencies of these clades are similar throughout the Mediterranean Sea, the levels of intra-clade genetic variation drop substantially towards the eastern end. This, together with clear differences in past demographic history and uneven migration rates between Mediterranean basins, suggests that the two populations experienced different effects during the Pleistocene. Subsequently, the mtDNA distinctiveness of eastern and western Mediterranean swordfish populations has been maintained probably by homing towards breeding areas.
Receptor‐promoted exocytosis of airway epithelial mucin granules containing a spectrum of adenine nucleotides
Authors: Kreda Silvia M. , Seminario‐Vidal Lucia , Van Heusden Catharina A. , O’Neal Wanda , Jones Lisa , Boucher Richard C. , Lazarowski Eduardo R.
Published: April 2010

Purinergic regulation of airway innate defence activities is in part achieved by the release of nucleotides from epithelial cells. However, the mechanisms of airway epithelial nucleotide release are poorly understood. We have previously demonstrated that ATP is released from ionomycin‐stimulated airway epithelial goblet cells coordinately with mucin exocytosis, suggesting that ATP is released as a co‐cargo molecule from mucin‐containing granules. We now demonstrate that protease‐activated‐receptor (PAR) agonists also stimulate the simultaneous release of mucins and ATP from airway epithelial cells. PAR‐mediated mucin and ATP release were dependent on intracellular Ca2+ and actin cytoskeleton reorganization since BAPTA AM, cytochalasin D, and inhibitors of Rho and myosin light chain kinases blocked both responses. To test the hypothesis that ATP is co‐released with mucin from mucin granules, we measured the nucleotide composition of isolated mucin granules purified based on their MUC5AC and VAMP‐8 content by density gradients. Mucin granules contained ATP, but the levels of ADP and AMP within granules exceeded by nearly 10‐fold that of ATP. Consistent with this finding, apical secretions from PAR‐stimulated cells contained relatively high levels of ADP/AMP, which could not be accounted for solely based on ATP release and hydrolysis. Thus, mucin granules contribute to ATP release and also are a source of extracellular ADP and AMP. Direct release of ADP/AMP from mucin granules is likely to provide a major source of airway surface adenosine to signal in a paracrine faction ciliated cell A2b receptors to activate ion/water secretion and appropriately hydrate goblet cell‐released mucins.
Estimation of ambient GABA levels in layer I of the mouse neonatal cortex in brain slices
Authors: Dvorzhak Anton , Myakhar Olga , Unichenko Petr , Kirmse Knut , Kirischuk Sergei
Published: April 2010

GABAergic synapses on Cajal–Retzius neurons in layer I of the murine neocortex experience GABAB receptor (GABABR)‐mediated tonic inhibition. Extracellular GABA concentration ([GABA]o) that determines the strength of GABABR‐mediated inhibition is controlled by GABA transporters (GATs). In this study, we hypothesized that the strength ofpresynaptic GABABR activation reflects [GABA]o in the vicinity of synaptic contacts. Slices obtained from two age groups were used, namely postnatal days (P)2–3 and P5–7. GABAergic postsynaptic currents (IPSCs) were recorded using the whole‐cell patch‐clamp technique. Minimal electrical stimulation in layer I was applied to elicit evoked IPSCs (eIPSCs) using a paired‐pulse protocol. Three parameters were selected for comparison: the mean eIPSC amplitude, paired‐pulse ratio, and failure rate. When GAT‐1 and GAT‐2/3 were blocked by NO‐711 (10 μm) and SNAP‐5114 (40 μm), respectively, no tonic GABABR‐mediated inhibition was observed. In order to restore the control levels of GABABR‐mediated inhibition, 250 and 125 nm exogenous GABA was required at P2–3 and P5–7, respectively. Addition of 3‐mercaptopropionic acid, a glutamate decarboxylase inhibitor, did not significantly change the obtained values arguing against the suggestion that a mechanism different from GATs contributes to [GABA]o control. We conclude that juxtasynaptic [GABA]o is higher (about 250 nm) at P2–3 than at P5–7 (about 125 nm). As both radial cell migration and corticogenesis in general are strongly dependent on [GABA]o and the formation of the last layer 2/3 is finished by P4 in rodents, the observed [GABA]o reduction in layer I might reflect this crucial event in the cortical development.
Peripheral chemoreceptors determine the respiratory sensitivity of central chemoreceptors to CO2
Authors: Blain Gregory M. , Smith Curtis A. , Henderson Kathleen S. , Dempsey Jerome A.
Published: April 2010

We assessed the contribution of carotid body chemoreceptors to the ventilatory response to specific CNS hypercapnia in eight unanaesthetized, awake dogs. We denervated one carotid body (CB) and used extracorporeal blood perfusion of the reversibly isolated remaining CB to maintain normal CB blood gases (normoxic, normocapnic perfusate), to inhibit (hyperoxic, hypocapnic perfusate) or to stimulate (hypoxic, normocapnic perfusate) the CB chemoreflex, while the systemic circulation, and therefore the CNS and central chemoreceptors, were exposed consecutively to four progressive levels of systemic arterial hypercapnia via increased fractional inspired CO2 for 7 min at each level. Neither unilateral CB denervation nor CB perfusion, per se, affected breathing. Relative to CB control conditions (normoxic, normocapnic perfusion), we found that CB chemoreflex inhibition decreased the slope of the ventilatory response to CNS hypercapnia in all dogs to an average of 19% of control values (range 0–38%; n= 6), whereas CB chemoreflex stimulation increased the slope of the ventilatory response to CNS hypercapnia in all dogs to an average of 223% of control values (range 204–235%; n= 4). We conclude that the gain of the CNS CO2/H+ chemoreceptors in dogs is critically dependent on CB afferent activity and that CNS–CB interaction results in hyperadditive ventilatory responses to central hypercapnia.
Sex‐ and age‐specific effects of nutrition in early gestation and early postnatal life on hypothalamo‐pituitary‐adrenal axis and sympathoadrenal function in adult sheep
Authors: Poore Kirsten R. , Boullin Julian P. , Cleal Jane K. , Newman James P. , Noakes David E. , Hanson Mark A. , Green Lucy R.
Published: April 2010

The early‐life environment affects risk of later metabolic disease, including glucose intolerance, insulin resistance and obesity. Changes in hypothalamo‐pituitary‐adrenal (HPA) axis and sympathoadrenal function may underlie these disorders. To determine consequences of undernutrition in early gestation and/or immediately following weaning on HPA axis and sympathoadrenal function, 2‐ to 3‐year‐old Welsh Mountain ewes received 100% (C, n= 39) or 50% nutritional requirements (U, n= 41) from 1–31 days gestation, and 100% thereafter. From weaning (12 weeks) to 25 weeks of age, male and female offspring were then either fed ad libitum (CC, n= 22; UC, n= 19) or were undernourished (CU, n= 17; UU, n= 22) such that body weight was reduced to 85% of their individual target, based on a growth trajectory calculated from weights taken between birth and 12 weeks. From 25 weeks, ad libitum feeding was restored for all offspring. At 1.5 and 2.5 years, adrenocorticotropic hormone (ACTH) and cortisol concentrations were measured at baseline and in response to corticotropin‐releasing factor (CRF) (0.5 μg kg−1) plus arginine vasopressin (AVP) (0.1 μg kg−1). At 2.5 years, HPA axis and sympathoadrenal (catecholamine) responses to a transport and isolation stress test were also measured. In females, post‐weaning undernutrition reduced pituitary output (ACTH) but increased adrenocortical responsiveness (cortisol:ACTH area under curve) during CRF/AVP challenge at 1.5 years and increased adrenomedullary output (adrenaline) to stress at 2.5 years. In males, cortisol responses to stress at 2.5 years were reduced in those with slower growth rates from 12 to 25 weeks. Early gestation undernutrition was associated with increased adrenocortical output in 2.5‐year‐old females only. Pituitary and adrenal responses were also related to adult body composition. Thus, poor growth in the post‐weaning period induced by nutrient restriction has sex‐ and age‐specific effects on HPA and sympathoadrenal function. With altered glucose tolerance previously reported in this model, this may have long‐term detrimental effects on metabolic homeostasis and cardiovascular function.
Synthesized Synchronous Sampling Technique for Differential Bearing Damage Detection
Authors: Luo Huageng , Qiu Hai , Ghanime George , Hirz Melinda , van der Merwe Geo
Published: April 2010

The differential bearing between the low-pressure turbine (LPT) and high-pressure turbine (HPT) shafts is one of the most vulnerable parts in a turbomachinery engine. Unfortunately, it is also one of the most difficult parts to monitor for damage existence signatures, because the signal-to-noise ratio at the normal sensor locations is extremely low. In addition, the speed variations in both the LPT and HPT can further deteriorate the damage signature extracted by conventional analysis methods. In this paper, we developed a “synthesized synchronous sampling” technique to enhance the detection of differential bearing damage signature. Combining this technique together with the conventional acceleration enveloping technique, we are able to detect differential bearing damage at a much earlier stage, thus providing early warnings of the machinery health conditions.
Development and Validation of a Thickened Flame Modeling Approach for Large Eddy Simulation of Premixed Combustion
Authors: Strakey Peter A. , Eggenspieler Gilles
Published: April 2010

The development of a dynamic thickened flame (TF) turbulence-chemistry interaction model is presented based on a novel approach to determine the subfilter flame wrinkling efficiency. The basic premise of the TF model is to artificially decrease the reaction rates and increase the species and thermal diffusivities by the same amount, which thickens the flame to a scale that can be resolved on the large eddy simulation (LES) grid while still recovering the laminar flame speed. The TF modeling approach adopted here uses local reaction rates and gradients of product species to thicken the flame to a scale large enough to be resolved by the LES grid. The thickening factor, which is a function of the local grid size and laminar flame thickness, is only applied in the flame region and is commonly referred to as dynamic thickening. Spatial filtering of the velocity field is used to determine the efficiency function by accounting for turbulent kinetic energy between the grid-scale and the thickened flame scale. The TF model was implemented into the commercial computational fluid dynamics code FLUENT. Validation in the approach is conducted by comparing model results to experimental data collected in a laboratory-scale burner. The burner is based on an enclosed scaled-down version of the low swirl injector developed at Lawrence Berkeley National Laboratory. A perfectly premixed lean methane-air flame was studied, as well as the cold-flow characteristics of the combustor. Planar laser induced fluorescence of the hydroxyl molecule was collected for the combusting condition, as well as the velocity field data using particle image velocimetry. Thermal imaging of the quartz liner surface temperature was also conducted to validate the thermal wall boundary conditions applied in the LES calculations.
Probabilistic Fretting Fatigue Assessment of Aircraft Engine Disks
Authors: Enright Michael P. , Chan Kwai S. , Moody Jonathan P. , Golden Patrick J. , Chandra Ramesh , Pentz Alan C.
Published: April 2010

Fretting fatigue is a random process that continues to be a major source of damage associated with the failure of aircraft gas turbine engine components. Fretting fatigue is dominated by the fatigue crack growth phase and is strongly dependent on the magnitude of the stress values in the contact region. These stress values often have the most influence on small cracks where traditional long-crack fracture mechanics may not apply. A number of random variables can be used to model the uncertainty associated with the fatigue crack growth process. However, these variables can often be reduced to a few primary random variables related to the size and location of the initial crack, variability associated with applied stress and crack growth life models, and uncertainty in the quality and frequency of nondeterministic inspections. In this paper, an approach is presented for estimating the risk reduction associated with the nondestructive inspection of aircraft engine components subjected to fretting fatigue. Contact stress values in the blade attachment region are estimated using a fine mesh finite element model coupled with a singular integral equation solver and combined with bulk stress values to obtain the total stress gradient at the edge of contact. This stress gradient is applied to the crack growth life prediction of a mode I fretting fatigue crack. A probabilistic model of the fretting process is formulated and calibrated using failure data from an existing engine fleet. The resulting calibrated model is used to quantify the influence of inspection on the probability of fracture of an actual military engine disk under real life loading conditions. The results can be applied to quantitative risk predictions of gas turbine engine components subjected to fretting fatigue.
Preliminary Testing of Metal-Based Thermal Barrier Coating in a Spark-Ignition Engine
Authors: Marr Michael A. , Wallace James S. , Pershin Larry , Chandra Sanjeev , Mostaghimi Javad
Published: April 2010

A novel metal-based thermal barrier coating was tested in a spark-ignition engine. The coating was applied to the surface of aluminum plugs and exposed to in-cylinder conditions through ports in the cylinder wall. Temperatures were measured directly behind the coating and within the plug 3 and 11 mm from the surface. In-cylinder pressures were measured and analyzed to identify and quantify knock. Test results suggest the coating does not significantly reduce overall heat transfer, but it does reduce the magnitude of temperature fluctuations at the substrate surface. It was found that heat transfer can be reduced by reducing the surface roughness of the coating. The presence of the coating did not promote knock.
A Lattice-Boltzmann Approach to Fluid Film Lubrication
Authors: Kucinschi Bogdan R. , Afjeh Abdollah A.
Published: April 2010

This paper deals with the application of the lattice-Boltzmann method (LBM) to fluid-film lubrication. Compared with the traditional computational approach in lubrication (based on Reynolds equation), LBM does not neglect inertia forces. The implementation of LBM is less demanding than that of the Navier–Stokes solvers for complex geometric configurations. Various wall boundary conditions, as well as the multiple relaxation time model, are discussed. Bearing cavitation is approached in a simplified manner. The LBM solutions for two classic configurations are compared with the corresponding analytic and numeric solutions of the Reynolds or Navier–Stokes equations. The LBM results were satisfactory for the investigated cases.
Analytical Solution to the Hydrodynamic Lubrication of Fan-Shaped Thrust Step Bearings
Authors: Liu Shuangbiao , Chen W. Wayne , Hua Diann Y.
Published: April 2010

Step bearings are frequently used in industries for better load capacities. Analytical solutions to the Rayleigh step bearing and a rectangular slider with a finite width are available in literature, but none for a fan-shaped thrust step bearing. This study starts with a known solution to the Laplace equation in a cylindrical coordinate system, which is in the form of an infinite summation. A set of analytical solutions to pressure, load capacity, flow rate, and torque loss is derived in this paper for hydrodynamic lubrication problems encountered in the fan-shaped step bearing. These analytical solutions are compared with those for the rectangular slider and the Rayleigh step bearing to reveal relationships among them. When the inner radius becomes smaller, the load capacity increases, almost linearly in a certain region. The effects of inner radius, step height, and step location on pressure distribution and load capacity are studied in general and under a specific set of bearing geometry as an example. The presented solutions can be useful for designers to maximize bearing performance as well as for researchers to benchmark numerical lubrication models.
A Numerical Study of Friction in Isothermal EHD Rolling-Sliding Sphere-Plane Contacts With Spinning
Authors: Dormois H. , Fillot N. , Habchi W. , Dalmaz G. , Vergne P. , Morales-Espejel G. E. , Ioannides E.
Published: April 2010

This paper presents a study of the spinning influence on film thickness and friction in EHL circular contacts under isothermal and fully flooded conditions. Pressure and film thickness profiles are computed with an original full-system finite element approach. Friction was thereafter investigated with the help of a classical Ree–Eyring model to calculate the longitudinal and transverse shear stresses. An analysis of both the velocity and shear stress distributions at every point of the contact surfaces has allowed explaining the fall of the longitudinal friction coefficient due to the occurrence of opposite shear stresses over the contact area. Moreover in the transverse direction spinning favors large shear stresses of opposite signs, decreasing the fluid viscosity by non-Newtonian effects. These effects have direct and coupled consequences on the friction reduction that is observed in the presence of spinning. They are expected to further decrease friction in real situations due to shear heating.
An Efficient Elastic Displacement Analysis Procedure for Simulating Transient Conformal-Contact Elastohydrodynamic Lubrication Systems
Authors: Xiong Shangwu , Lin Chih , Wang Yansong , Liu Wing Kam , Wang Q. Jane
Published: April 2010

A compliance operator is often utilized to evaluate the elastic displacement of surfaces in the simulation of transient and steady-state elastohydrodynamic lubrication of conformal-contact systems. The values of the compliance operator represent the elastic responses of all nodes when only one node is under a unit load. The accuracy of compliance operator values, computational cost, and storage size are important issues. Our study of steady-state conformal-contact elastohydrodynamic lubrication analyses suggests a method of selective-fine-mesh with selective-storage, as well as a special technique of the combined selective-fine-mesh with selective-storage mapping. These two techniques enable an efficient elasticity procedure for the simulation of steady-state and transient conformal-contact elastohydrodynamic lubrication systems by means of the finite element method.
Design and Performance of Slurry Erosion Tester
Authors: Abouel-Kasem A. , Abd-elrhman Y. M. , Emara K. M. , Ahmed S. M.
Published: April 2010

A slurry whirling arm erosion test ring was constructed and a series of erosion tests and post-erosion analysis were carried out using a paint erosion indication technique. The pattern of the paint removal presented a highly visual and accelerated map for the erosion process and its behavior. Also, the erosion rate of paint removal was investigated under a number of erosion variables. It was observed that the rebounding of the erodent particles from the sample surface play an important role in developing erosion for this tester. The erosion pattern showed that the effect of the rebound particles depends on the impact velocity and impingement angle. It was also observed that the erosion behavior of paint as a function of impingement angle, impact velocity, and erosion time was similar to that reported in literature for engineering materials. The slurry whirling arm erosion tester seems to be promising for simulating the slurry process in real cases.
Structural properties of C60-multivalent metal composite layers grown by molecular beam epitaxy
Authors: Nishinaga Jiro , Horikoshi Yoshiji
Published: April 2010

C 60 -multivalent metal composite layers (aluminum, gallium, and germanium) are grown on GaAs and quartz glass substrates by molecular beam epitaxy. The structural properties of the C60-metal composite layers are investigated by reflection high-energy electron diffraction and transmission electron microscopy measurements, and it is confirmed that these layers have an amorphous structure. Mechanical properties of the layers are investigated by Vickers hardness test, and the values of the C60-metal composite layers are confirmed to be dramatically increased. The structural change and the hardness enhancement are induced by the bonding between C60 molecules and multivalent metal atoms. Optical properties of the layers are measured by the absorption coefficient spectra. The absorption peaks in C60–Ge composite layers become less pronounced with increasing Ge concentration and the intensity in visible light spectrum is increased. Pure C60, C60–Al, and C60–Ga composite layers are confirmed to be insulators in air. In contrast, the conductivity of a C60–Ge composite layer is found to be 0.02 Ω−1 cm−1 at room temperature with an activation energy of 120 meV. These enhancements of absorption coefficient and conductivity are very important for solar cells applications.
Dimerization as a Drug Target
Authors: Wong Wei
Published: April 2010

The flavonol quercetin stabilizes the dimeric active form of the intracellular stress sensor IRE1.
Focus Issue: Teaching Tools and Learning Opportunities
Authors: Gough Nancy R.
Published: April 2010

Science Signaling
provides authoring experience for students and resources for educators.
Costimulatory Role of CXCR4 with Pre-TCR and Its Crosstalk with PI3K in β-Selection of Thymocytes
Authors: Ahamed J. Ashik , Madhivadhani Periasamy
Published: April 2010

Chemokine and pre-TCR signaling cooperate in β-selection of thymocytes and promote their subsequent proliferation.
New Regulator for Energy Signaling Pathway in Plants Highlights Conservation Among Species
Authors: Meyer Anne K. , Longin C. Friedrich H. , Klose Christian , Hermann Andreas
Published: April 2010

The kinase CIPK links plant pathways involved in oxygen-sensing and carbohydrate metabolism.
Identification of TEM-135 β-Lactamase in Penicillinase-ProducingNeisseria gonorrhoeaeStrains in Japan
Authors: Ohnishi Makoto , Ono Emi , Shimuta Ken , Watanabe Haruo , Okamura Noboru
Published: April 2010

Ten penicillinase-producingNeisseria gonorrhoeae(PPNG) strains isolated from 2000 to 2008 were characterized by multilocus sequence typing, multiantigen sequence typing, and plasmid typing. Sequence analysis showed that 8 strains contained a TEM-1 β-lactamase gene. However, two other genetically distinct PPNG strains, isolated in 2004 and 2008, each contained a TEM-135 β-lactamase on different plasmids, a Toronto/Rio type R plasmid and an Asia type R plasmid, suggesting independent origins of these PPNG strains.
Role of the Surface Lipoprotein BBA07 in the Enzootic Cycle ofBorrelia burgdorferi
Authors: Xu Haijun , He Ming , He Jane Jingyuan , Yang X. Frank
Published: April 2010

Borrelia burgdorferi, the Lyme disease pathogen, dramatically alters its protein profile when it is transmitted between ticks and mammals. Several differentially expressed proteins have been shown to be critical for the enzootic cycle ofB. burgdorferi. In this study, we demonstrated that expression of the surface lipoprotein-encoding genebba07is induced by an elevated temperature and a reduced pH duringin vitrocultivation, as well as during nymphal tick feeding. Expression ofbba07is regulated by the Rrp2-RpoN-RpoS pathway, a central regulatory network that is activated during nymphal feeding. By generating abba07mutant of an infectious strain ofB. burgdorferi, we demonstrated that although BBA07-deficient spirochetes were capable of infecting mice via needle inoculation and surviving in ticks, they were defective in infection of mammals via tick transmission. Complementation of thebba07mutant with a wild-type copy ofbba07partially restored the transmission defect of thebba07mutant. Based on these findings, we concluded that the surface lipoprotein BBA07 is produced during tick feeding and facilitates optimal transmission ofB. burgdorferifrom the tick vector to a mammalian host.
Use of Amplified Fragment Length Polymorphism To Identify 42
Cladophialophora
Strains Related to Cerebral Phaeohyphomycosis with In Vitro Antifungal Susceptibility
Authors: Badali Hamid , de Hoog G. Sybren , Curfs-Breuker Ilse , Klaassen Corné H. W. , Meis Jacques F.
Published: April 2010

The amplified fragment length polymorphism technique has been applied to identify neurotropic chaetothyrialean black yeasts and relatives from clinical sources.
Cladophialophora bantiana
,
C. emmonsii
,
C. arxii
,
C. devriesii
, and
C. modesta
, previously identified on the basis of sequencing and phenotypic and physiological criteria, were confirmed by cluster analysis, demonstrating the clear separation of
C. bantiana
as a rather homogeneous group from the other species.
C. bantiana
is a neurotropic fungus causing cerebral abscesses with a mortality of up to 70%. Successful therapy consists of neurosurgical intervention and optimal antifungal therapy. Since the latter is not clearly defined in a large series, we tested the
in vitro
activities of eight antifungal drugs against clinical isolates of
C. bantiana
(
n
= 37),
C. modesta
(
n
= 2),
C. arxii
(
n
= 1),
C. emmonsii
(
n
= 1), and
C. devriesii
(
n
= 1), all of which had caused invasive infections. The resulting MIC
90
s for all neurotropic
C. bantiana
strains were as follows, in increasing order: posaconazole, 0.125 μg/ml; itraconazole, 0.125 μg/ml; isavuconazole, 0.5 μg/ml; amphotericin B, 1 μg/ml; voriconazole, 2 μg/ml; anidulafungin, 2 μg/ml; caspofungin, 4 μg/ml; and fluconazole, 64 μg/ml. On the basis of these
in vitro
results and the findings of previous clinical and animal studies, posaconazole seems to be a good alternative to the standard treatment, amphotericin B, for
C. bantiana
cerebral infections. The new agent isavuconazole, which is also available as an intravenous preparation, has adequate activity against
C. bantiana
.
Breakthrough Invasive Candidiasis in Patients on Micafungin
Authors: Pfeiffer Christopher D. , Garcia-Effron Guillermo , Zaas Aimee K. , Perfect John R. , Perlin David S. , Alexander Barbara D.
Published: April 2010

For
Candida
species, a bimodal wild-type MIC distribution for echinocandins exists, but resistance to echinocandins is rare. We characterized isolates from patients with invasive candidiasis (IC) breaking through ≥3 doses of micafungin therapy during the first 28 months of its use at our center: MICs were determined and hot-spot regions within
FKS
genes were sequenced. Eleven of 12 breakthrough IC cases identified were in transplant recipients. The median duration of micafungin exposure prior to breakthrough was 33 days (range, 5 to 165). Seventeen breakthrough isolates were recovered:
FKS
hot-spot mutations were found in 5
C. glabrata
and 2
C. tropicalis
isolates; of these, 5 (including all
C. glabrata
isolates) had micafungin MICs of >2 μg/ml, but all demonstrated caspofungin MICs of >2 μg/ml. Five
C. parapsilosis
isolates had wild-type
FKS
sequences and caspofungin MICs of 0.5 to 1 μg/ml, but 4/5 had micafungin MICs of >2 μg/ml. The remaining isolates retained echinocandin MICs of ≤2 μg/ml and wild-type
FKS
gene sequences. Breakthrough IC on micafungin treatment occurred predominantly in severely immunosuppressed patients with heavy prior micafungin exposure. The majority of cases were due to
C. glabrata
with an
FKS
mutation or wild-type
C. parapsilosis
with elevated micafungin MICs. MIC testing with caspofungin identified all mutant strains. Whether the naturally occurring polymorphism within the
C. parapsilosis FKS1
gene responsible for the bimodal wild-type MIC distribution is also responsible for micafungin MICs of >2 μg/ml and clinical breakthrough or an alternative mechanism contributes to the nonsusceptible echinocandin MICs in
C. parapsilosis
requires further study.