bluuebunny/crossref_metadata_2025 huggingface dataset:
A statistical study of the spatial structure of interplanetary magnetic field substorm triggers and their associated magnetic response
Authors: Hsu Tung‐Shin , McPherron Robert L.
Published: February 2009

An outstanding question in magnetospheric physics is whether substorms are always triggered externally by changes in the interplanetary magnetic field (IMF) or solar wind plasma, or whether they sometimes occur spontaneously as a result of internal processes. An apparent association between northward turnings of the IMF and substorm onset has been frequently demonstrated, but it is also found that not all substorms are triggered. Previous studies have shown that the ratio of triggered and nontriggered substorms is about 60/40. A surprising finding is that substorms classified as triggered exhibit a stronger response than nontriggered substorms. It has been suggested that this may be due to undetected small‐scale structures in the IMF which presumably have weak driving fields of short duration and hence transfer less energy to the magnetosphere. In this work we use a large database of 1978∼1985 ISEE 2 and IMP 8 IMF observations to investigate whether small‐scale structures occur frequently enough to account for the 40% nontriggered substorms. We find that the probability of observing IMF small‐scale structures is less than 13%. This low probability (13%) does not match the occurrence frequency of 40% for nontriggered substorm onsets. It is thus unlikely that all nontriggered substorms can be attributed to small‐scale IMF structures missed by an upstream monitor. Another interesting finding is that the small‐scale IMF Bz triggers do not seem to create significant AL response but the large‐scale IMF Bz triggers do. The median curve shows a sudden sharp drop of the AL index at the time the IMF trigger is expected to arrive at the magnetopause. This suggests that some substorms must be associated with the IMF triggers.
Tracking magma volume recovery at Okmok volcano using GPS and an unscented Kalman filter
Authors: Fournier Thomas , Freymueller Jeff , Cervelli Peter
Published: February 2009

Changes beneath a volcano can be observed through position changes in a GPS network, but distinguishing the source of site motion is not always straightforward. The records of continuous GPS sites provide a favorable data set for tracking magma migration. Dense campaign observations usually provide a better spatial picture of the overall deformation field, at the expense of an episodic temporal record. Combining these observations provides the best of both worlds. A Kalman filter provides a means for integrating discrete and continuous measurements and for interpreting subtle signals. The unscented Kalman filter (UKF) is a nonlinear method for time‐dependent observations. We demonstrate the application of this technique to deformation data by applying it to GPS data collected at Okmok volcano. Seven years of GPS observations at Okmok are analyzed using a Mogi source model and the UKF. The deformation source at Okmok is relatively stable at 2.5 km depth below sea level, located beneath the center of the caldera, which means the surface deformation is caused by changes in the strength of the source. During the 7 years of GPS observations more than 0.5 m of uplift has occurred, a majority of that during the time period January 2003 to July 2004. The total volume recovery at Okmok since the last eruption in 1997 is ∼60–80%. The UKF allows us to solve simultaneously for the time‐dependence of the source strength and for the location without a priori information about the source.
Evidence from coseismic slip gradients for dynamic control on rupture propagation and arrest through stepovers
Authors: Elliott A. J. , Dolan J. F. , Oglesby D. D.
Published: February 2009

Analysis of historic slip distributions from large‐magnitude continental strike‐slip earthquake ruptures reveals a pronounced correlation between the distance over which slip decreases as a rupture approaches a structural “step” in the fault and the ability of the rupture to propagate through the step. Our analysis of coseismic slip gradients near these stepovers indicates that in earthquakes in which slip decreases gradually toward a step, rupture will not continue on the next segment. Conversely, in earthquakes in which slip decreases abruptly, rupture commonly renucleates on the next segment. The fact that ruptures that stopped had low slip gradients near stepovers, relative to those that continued, indicates that rupture dynamics control the propagation of rupture through stepovers. These results corroborate dynamic rupture models that show that ruptures in which slip decreases abruptly at a step generate strong seismic waves that serve to renucleate rupture on the opposite side of the structural step. There are several potential causes for gradual decrease of displacement as rupture approaches a stepover, including transference of deformation onto subsidiary structures, rheological contrasts that could dictate favored rupture propagation directions, the existence of stress shadows from previous earthquakes within the system, or other material or frictional heterogeneities. All of these are potentially observable, and, if mapped systematically, could provide the basis for a strong constraint on the likely end points of future earthquakes. Inasmuch as earthquake magnitude is strongly dependent on the size of the rupture, such predictions would be of great utility as a basic component of scenario‐based earthquake rupture forecasts.
Elastic wave speeds and moduli in polycrystalline ice Ih, sI methane hydrate, and sII methane‐ethane hydrate
Authors: Helgerud M. B. , Waite W. F. , Kirby S. H. , Nur A.
Published: February 2009

We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory‐formed polycrystalline ice Ih, sI methane hydrate, and sII methane‐ethane hydrate. From the wave speed's linear dependence on temperature and pressure and from the sample's calculated density, we derived expressions for bulk, shear, and compressional wave moduli and Poisson's ratio from −20 to −5°C and 22.4 to 32.8 MPa for ice Ih, −20 to 15°C and 30.5 to 97.7 MPa for sI methane hydrate, and −20 to 10°C and 30.5 to 91.6 MPa for sII methane‐ethane hydrate. All three materials had comparable P and S wave speeds and decreasing shear wave speeds with increasing applied pressure. Each material also showed evidence of rapid intergranular bonding, with a corresponding increase in wave speed, in response to pauses in sample deformation. There were also key differences. Resistance to uniaxial compaction, indicated by the pressure required to compact initially porous samples, was significantly lower for ice Ih than for either hydrate. The ice Ih shear modulus decreased with increasing pressure, in contrast to the increase measured in both hydrates.
Absolute flow field estimation for the Nordic seas from combined gravimetric, altimetric, and in situ data
Authors: Hunegnaw A. , Siegismund F. , Hipkin R. , Mork K. A.
Published: February 2009

In the Nordic seas, we combine a computation of absolute surface current flow derived from geodetic data with in situ historical hydrographic data to estimate the absolute volume, heat, and salt transports as a function of depth. Our mean dynamic topography (MDT) is calculated from marine, airborne and satellite gravimetry, combined with satellite altimetry, using a new algorithm called the iterative combination method (ICM). Residual noise in the gravimetric geoid is the limit on MDT resolution and is suppressed using a Gaussian filter with a width at half‐peak amplitude of 59 km. Detailed and coherent flow paths for surface geostrophic currents are clearly identified. ICM MDT was used as fixed boundary condition to transform historical hydrography into absolute estimates of volume, heat, and salt transport, replacing the assumption of an isobaric surface at a predetermined depth. For the inflow of Atlantic Water (potential temperature Θ > 6°C) through the Faroe‐Shetland Channel into the Nordic seas, we obtain time‐averaged fluxes between 1993 and 1996 of 3.5 Sv (volume), 121 TW (heat), and 124 × 106 kg s−1 (salt), very close to reported observations from acoustic Doppler current profiler moorings and conductivity‐temperature‐depth data. For the Svinøy section, we obtain a northward transport of Atlantic Water (S > 35.0, T > 5.0°C) of 3.9 Sv in the eastern branch of the Norwegian Atlantic Current comparable with reported measurements of 4.2 Sv. Similarly good agreement is found for the Hornbanki and Iceland‐Faroe Ridge sections and for monitoring Atlantic Water outflow across the Barents Sea Opening to the Arctic shelf.
The role of initial conditions and forcing uncertainties in seasonal hydrologic forecasting
Authors: Li Haibin , Luo Lifeng , Wood Eric F. , Schaake John
Published: February 2009

A series of hydrologic forecasts with lead times up to 6 months are conducted to investigate the relative contributions of atmospheric forcing and hydrologic initial conditions (IC) to the overall errors in hydrologic forecasting during cold and warm seasons. These experiments are known as the ensemble streamflow prediction (ESP) and the reverse‐ESP (R‐ESP). Analysis of these hindcasts suggests that IC uncertainties outweigh forcing uncertainties thus dominating forecast errors in a short lead time up to about 1 month; at longer lead times, forcing uncertainties become a more important contributor. Further investigation shows that forecast errors at short lead times due to uncertain ICs are mainly determined by the prescribed IC variability, while the evolution of forecast errors due to imperfect atmospheric forcings mainly corresponds to the interannual variability of precipitation. With respect to difference in forecasts initialized in winter and summer times, ICs tend to have longer impacts on warm season forecasts than on cold season ones, due mainly to drier initial moisture state in the summer time. As far as the basin size is concerned, we find that the larger the basin, the stronger the impacts from ICs at short lead times. Small basins are more sensitive to forcing fields. Regardless of basin size, forcing uncertainties dominate relative forecast errors for long lead times. In order to see whether statistically downscaled forcing fields from dynamic climate models are more skillful than traditional ESP, we conducted additional ESP‐type experiments using the statistically downscaled climate forecast system (CFS) fields to drive the hydrological model. In comparison to traditional ESP, the IC errors show a larger impact on the forecasts when forced by the CFS fields, which suggests that the latter contains more skill than the traditional ESP approach.
Modeling on multi‐eigenpath channel in marine atmospheric duct
Authors: Zhao Xiao‐long , Huang Ji‐ying , Gong Shu‐hong
Published: February 2009

A multi‐eigenpath channel model is proposed to simulate the microwave transhorizon communication signal in marine atmospheric duct environment. The channel model identifies the relation between multiperiodical delay components and subeigenpath components. The simplified algorithm of subeigen signal is proposed on the basis on signal‐to‐multipath ratio. The application procedure of this model is described. The bit error rate of binary phase shift keying moduted signal in atmospheric duct is simulated by multi‐eigenpath channel model.
Soil amoebae rapidly change bacterial community composition in the rhizosphere of Arabidopsis thaliana
Authors: Rosenberg Katja , Bertaux Joanne , Krome Kristin , Hartmann Anton , Scheu Stefan , Bonkowski Michael
Published: February 2009

We constructed an experimental model system to study the effects of grazing by a common soil amoeba, Acanthamoeba castellanii, on the composition of bacterial communities in the rhizosphere of Arabidopsis thaliana. Amoebae showed distinct grazing preferences for specific bacterial taxa, which were rapidly replaced by grazing tolerant taxa in a highly reproducible way. The relative proportion of active bacteria increased although bacterial abundance was strongly decreased by amoebae. Specific bacterial taxa had disappeared already two days after inoculation of amoebae. The decrease in numbers was most pronounced in Betaproteobacteria and Firmicutes. In contrast, Actinobacteria, Nitrospira, Verrucomicrobia and Planctomycetes increased. Although other groups, such as betaproteobacterial ammonia oxidizers and Gammaproteobacteria did not change in abundance, denaturing gradient gel electrophoresis with specific primers for pseudomonads (Gammaproteobacteria) revealed both specific changes in community composition as well as shifts in functional genes (gacA) involved in bacterial defence responses. The resulting positive feedback on plant growth in the amoeba treatment confirms that bacterial grazers play a dominant role in structuring bacteria–plant interactions. This is the first detailed study documenting how rapidly protozoan grazers induce shifts in rhizosphere bacterial community composition.
Quantitative population dynamics of microbial communities in plankton-fed microbial fuel cells
Authors: White Helen K , Reimers Clare E , Cordes Erik E , Dilly Geoffrey F , Girguis Peter R
Published: February 2009

This study examines changes in diversity and abundance of bacteria recovered from the anodes of microbial fuel cells (MFCs) in relation to anode potential, power production and geochemistry. MFCs were batch-fed with plankton, and two systems were maintained at different potentials whereas one was at open circuit for 56.8 days. Bacterial phylogenetic diversity during peak power was assessed from 16S rDNA clone libraries. Throughout the experiment, microbial community structure was examined using terminal restriction fragment length polymorphism. Changes in cell density of key phylotypes, including representatives of δ-, ɛ-, γ-proteobacteria and Flavobacterium-Cytophaga-Bacteroides, were enumerated by quantitative PCR. Marked differences in phylogenetic diversity were observed during peak power versus the final time point, and changes in microbial community structure were strongly correlated to dissolved organic carbon and ammonium concentrations within the anode chambers. Community structure was notably different between the MFCs at different anode potentials during the onset of peak power. At the final time point, however, the anode-hosted communities in all MFCs were similar. These data demonstrate that differences in growth, succession and population dynamics of key phylotypes were due to anode potential, which may relate to their ability to exploit the anode as an electron acceptor. The geochemical milieu, however, governs overall community diversity and structure. These differences reflect the physiological capacity of specific phylotypes to catabolize plankton-derived organic matter and exploit the anode of an MFC for their metabolism directly or indirectly through syntrophy.
Horizontal gene transfer between Ralstonia solanacearum strains detected by comparative genomic hybridization on microarrays
Authors: Guidot Alice , Coupat Bénédicte , Fall Saliou , Prior Philippe , Bertolla Franck
Published: February 2009

The plant pathogenic Betaproteobacterium Ralstonia solanacearum is a complex species in that most of the strains share the common characteristic of being naturally transformable. In this study, we used a new approach based on comparative genomic hybridization (CGH) on microarrays to investigate the extent of horizontal gene transfers (HGTs) between different strains of R. solanacearum. Recipient strains from phylotypes I, II and III were naturally transformed in vitro by genomic DNA from the GMI1000 reference strain (phylotype I) and the resulting DNAs were hybridized on a microarray representative of the 5120 predicted genes from the GMI1000 strain. In addition to transfer of the antibiotic resistance marker, in 8 of the 16 tested transformants, CGH on microarrays detected other transferred GMI1000 genes and revealed their number, category, function and localization along the genome. We showed that DNA blocks up to 30 kb and 33 genes could be integrated during a single event. Most of these blocks flanked the marker gene DNA but, interestingly, multiple DNA acquisitions along the genome also occurred in a single recombinant clone in one transformation experiment. The results were confirmed by PCR amplification, cloning and sequencing and Southern blot hybridization. This represents the first comprehensive identification of gene acquisitions and losses along the genome of the recipient bacterial strain during natural transformation experiments. In future studies, this strategy should help to answer many questions related to HGT mechanisms.
The onset of microbial associations in the coral Pocillopora meandrina
Authors: Apprill Amy , Marlow Heather Q , Martindale Mark Q , Rappé Michael S
Published: February 2009

Associations between healthy adult reef-building corals and bacteria and archaea have been observed in many coral species, but the initiation of their association is not understood. We investigated the onset of association between microorganisms and Pocillopora meandrina, a coral that vertically seeds its eggs with symbiotic dinoflagellates before spawning. We compared the bacterial communities associated with prespawned oocyte bundles, spawned eggs, and week old planulae using multivariate analyses of terminal restriction fragment length polymorphisms of SSU rRNA genes, which revealed that the composition of bacteria differed between these life stages. Additionally, planulae raised in ambient seawater and seawater filtered to reduce the microbial cell density harbored dissimilar bacterial communities, though SSU rRNA gene clone libraries showed that planulae raised in both treatments were primarily associated with different members of the Roseobacter clade of Alphaproteobacteria. Fluorescent in situ hybridization with an oligonucleotide probe suite targeting all bacteria and one oligonucleotide probe targeting members of the Roseobacter clade was used to localize the bacterial cells. Only planulae greater than 3 days old were observed to contain internalized bacterial cells, and members of the Roseobacter clade were detected in high abundance within planula tissues exposed to the ambient seawater treatment. We conclude that the onset of association between microorganisms and the coral P. meandrina appears to occur through horizontal uptake by planulae older than 79 h, and that uptake is preferential to members of the Roseobacter clade and potentially sensitive to the ambient seawater microbial community.
Assembling the Tree of Life in Europe (AToLE)
Authors: Bininda-Emonds Olaf , Bogdanowicz Wieslaw , Borsch Thomas , Delsuc Frederic , Hassanin Alexandre , Jondelius Ulf , Petersen Gitte , Renner Susanne , Savolainen Vincent , Seberg Ole , Smets Erik , Vogler Alfried
Published: February 2009

A network of scientists under the umbrella of 'Assembling the Tree of Life in Europe (AToLE)' seeks funding under the FP7-Theme: Cooperation - Environment (including Climate Change and Biodiversity Conservation) programme of the European Commission.
COX‐2‐mediated Inflammation in Fat Is Crucial for Obesity‐linked Insulin Resistance and Fatty Liver
Authors: Hsieh Po‐Shiuan , Jin Jong‐Shiaw , Chiang Chih‐Fan , Chan Pei‐Chi , Chen Chih‐Hao , Shih Kuang‐Chung
Published: February 2009

The aim was to examine the role of cyclooxygenase (COX)‐2‐mediated inflammation in the development of obese linked insulin resistance and fatty liver. The rats were fed separately regular diet (CONT), high‐fat diet (HFD) ad libitum, or energy restrictedly for 12 weeks. Rats fed HFD ad libitum were further divided into three subgroups co‐treated with vehicle (HFa), or a selective COX‐2 inhibitor celecoxib (HFa‐Cel) or mesulid (HFa‐Mes). Euglycemic hyperinsulinemic clamp (EHC) experiment was performed at the end of study. Another set of rats with similar grouping was further divided into those with a 4, 8, or 12‐week intervention period for hepatic sampling. Body weight was increased significantly and similarly in HFa, HFa‐Cel, and HFa‐Mes. Time‐dependent increases in plasma insulin, glucose, 8‐isoprostanes, leptin levels, homeostasis model assessment of insulin resistance (HOMA‐IR) and hepatic triglyceride contents shown in HFa were significantly reversed in HFa‐Cel and HFa‐Mes. During EHC period, the reduction in stimulation of whole body glucose uptake, suppression of hepatic glucose production and metabolic clearance rate of insulin shown in HFa were significantly reversed in HFa‐Cel and HFa‐Mes. The enhanced COX‐2 and tumor necrosis factor‐α (TNF‐α) but attenuated PPAR‐γ and C/EBP‐α mRNA expressions in epididymal fat shown in HFa were significantly reversed in HFa‐Cel and HFa‐Mes. The increases in average cell size of adipocytes and CD68 positive cells shown in HFa were also significantly reversed in HFa‐Cel and HFa‐Mes. Our findings suggest that COX‐2 activation in fat inflammation is important in the development of insulin resistance and fatty liver in high fat induced obese rats.
Long‐term Exercise Training in Overweight Adolescents Improves Plasma Peptide YY and Resistin
Authors: Jones Terry E. , Basilio J.L. , Brophy P.M. , McCammon M.R. , Hickner R.C.
Published: February 2009

The objective of this study was to investigate the effect of long‐term exercise training on concentrations of five hormones related to appetite and insulin resistance in overweight adolescents. In addition, we were interested in the relationships of these hormones with each other and with anthropometric and/or cardiovascular disease marker changes. Participants were ≥ the 85th percentile for BMI for age and sex and participated in an 8‐month supervised aerobic training program. Anthropometrics, cardiovascular fitness assessment, and fasting blood samples were taken pre‐ and post‐training. Glucose, insulin, total cholesterol (TC), high‐density lipoprotein (HDL) cholesterol, low‐density lipoprotein (LDL) cholesterol, triglycerides, leptin, active ghrelin, total peptide YY (PYY), adiponectin, and resistin concentrations were measured. The participants increased their time to exhaustion on an incremental treadmill test and decreased both percent body fat and blood triglyceride concentrations. Total PYY concentration increased and resistin concentration decreased after long‐term exercise training, which are favorable outcomes. Leptin concentrations were related to weight, percent body fat, waist circumference, and triglyceride concentrations pre‐ and post‐training. The changes in resistin concentrations were related to the changes in triglyceride concentrations. We conclude that long‐term exercise training has beneficial effects for overweight adolescents with respect to PYY and resistin, hormones related to appetite and insulin sensitivity.
Resistance Training Preserves Fat‐free Mass Without Impacting Changes in Protein Metabolism After Weight Loss in Older Women
Authors: Campbell Wayne W. , Haub Mark D. , Wolfe Robert R. , Ferrando Arny A. , Sullivan Dennis H. , Apolzan John W. , Iglay Heidi B.
Published: February 2009

This study assessed the effects of resistance training (RT) on energy restriction–induced changes in body composition, protein metabolism, and the fractional synthesis rate of mixed muscle proteins (FSRm) in postmenopausal, overweight women. Sixteen women (age 68 ± 1 years, BMI 29 ± 1 kg/m2, mean ± s.e.m.) completed a 16‐week controlled diet study. Each woman consumed 1.0 g protein/kg/day. At baseline (weeks B1–B3) and poststudy (weeks RT12–RT13), energy intake matched each subject's need and during weeks RT1–RT11 was hypoenergetic by 2,092 kJ/day (500 kcal/day). From weeks RT1 to RT13, eight women performed RT 3 day/week (RT group) and eight women remained sedentary (SED group). RT did not influence the energy restriction–induced decrease in body mass (SED −5.8 ± 0.6 kg; RT −5.0 ± 0.2 kg) and fat mass (SED −4.1 ± 0.9 kg; RT −4.7 ± 0.5 kg). Fat free mass (FFM) and total body water decreased in SED (−1.6 ± 0.4 and −2.1 ± 0.5 kg) and were unchanged in RT (−0.3 ± 0.4 and −0.4 ± 0.7 kg) (group‐by‐time, P ≤ 0.05 and P = 0.07, respectively). Protein–mineral mass did not change in either group (SED 0.4 ± 0.2 kg; RT 0.1 ± 0.4 kg). Nitrogen balance, positive at baseline (2.2 ± 0.3 g N/day), was unchanged poststudy. After body mass loss, postabsorptive (PA) and postprandial (PP) leucine turnover, synthesis, and breakdown decreased. Leucine oxidation and balance were not changed. PA and total (PA + PP) FSRm in the vastus lateralis were higher after weight loss. RT did not influence these protein metabolism responses. In summary, RT helps older women preserve FFM during body mass loss. The comparable whole‐body nitrogen retentions, leucine kinetics, and FSRm between groups are consistent with the lack of differential protein–mineral mass change.
Low Fasting Triglycerides: Hallmark of the Healthy Large Hip?
Authors: Ruige Johannes B. , Van Gaal Luc F.
Published: February 2009

Body fat distribution modulates risk for type 2 diabetes mellitus. We evaluated potentially involved metabolic risk factors. In a population of 282 male and 157 female healthy subjects (data from the San Antonio and the European Group of Insulin Resistance (EGIR) study cohorts), we evaluated associations between body fat distribution (assessed by waist and hip circumference) and parameters of lipid‐ and glucose metabolism, including clamp measurements of insulin sensitivity. After stratification for BMI, fasting triglycerides were lower in the presence of a large hip, and higher in a large waist. Persons with the largest BMI (3rd tertile) showed a difference in triglyceride levels of 1.5 vs. 2.4 mmol/l in large vs. small hip circumference groups (P < 0.038), and a difference of 1.5 vs. 1.2 mmol/l in large vs. small waist circumference groups (P < 0.025). A similar analysis did not reveal a difference in insulin sensitivity. Linear regression analyses confirmed the findings; they revealed negative associations between triglycerides and hip, and (for women borderline statistically significant) positive associations between triglycerides and waist, after adjustment for BMI, mutual confounding, and age (β ± s.e.; men: −0.48 ± 0.005, P < 0.001, and 0.21 ± 0.005, P < 0.05; women: −0.78 ± 0.007, P < 0.001, and 0.24 ± 0.005, P < 0.065), respectively. Linear regression analyses revealed similar opposite associations with high‐density lipoprotein (HDL)‐cholesterol, though not with glucose, insulin, or insulin sensitivity as measured with the clamp method. In our study population of healthy persons, body fat distribution is associated with fasting triglycerides and HDL‐cholesterol, and not with insulin sensitivity. Metabolic risk of unfavorable body fat distribution may be modulated by lower triglyceride storage capacity.
Association Between the 4 bp Proinsulin Gene Insertion Polymorphism (IVS‐69) and Body Composition in Black South African Women
Authors: Berman Peter , Collins Malcolm , Baumgarten Ingrid , Seoighe Cathal , Jennings Courtney L. , Joffe Yael , Lambert Estelle V. , Levitt Naomi S. , Faulenbach Mirjam V. , Kahn Steven E. , Goedecke Julia H.
Published: February 2009

The objective of the study was to examine the association between a functional 4 bp proinsulin gene insertion polymorphism (IVS‐69), fasting insulin concentrations, and body composition in black South African women. Body composition, body fat distribution, fasting glucose and insulin concentrations, and IVS‐69 genotype were measured in 115 normal‐weight (BMI <25 kg/m2) and 138 obese (BMI ≥30 kg/m2) premenopausal women. The frequency of the insertion allele was significantly higher in the class 2 obese (BMI ≥35kg/m2) compared with the normal‐weight group (P = 0.029). Obese subjects with the insertion allele had greater fat mass (42.3 ± 0.9 vs. 38.9 ± 0.9 kg, P = 0.034) and fat‐free soft tissue mass (47.4 ± 0.6 vs. 45.1 ± 0.6 kg, P = 0.014), and more abdominal subcutaneous adipose tissue (SAT, 595 ± 17 vs. 531 ± 17 cm2, P = 0.025) but not visceral fat (P = 0.739), than obese homozygotes for the wild‐type allele. Only SAT was greater in normal‐weight subjects with the insertion allele (P = 0.048). There were no differences in fasting insulin or glucose levels between subjects with the insertion allele or homozygotes for the wild‐type allele in the normal‐weight or obese groups. In conclusion, the 4 bp proinsulin gene insertion allele is associated with extreme obesity, reflected by greater fat‐free soft tissue mass and fat mass, particularly SAT, in obese black South African women.
Similarities in Food Cravings and Mood States Between Obese Women and Women Who Smoke Tobacco
Authors: Pepino M. Yanina , Finkbeiner Susana , Mennella Julie A.
Published: February 2009

The present study assessed food cravings in a cohort of 229 women who differed in smoking history (i.e., never smoker, former smoker, and current smoker) and body weight (i.e., normal weight, overweight, and obese). Each subject completed the Food Craving Inventory (FCI), which measures cravings for sweets, high fats, carbohydrates/starches, and fast‐food fats, and the Profile of Mood States (POMS), which measures psychological distress. Smoking and obesity were independently associated with specific food cravings and mood states. Current smokers craved high fats more frequently than former and never smokers. They also craved starches more frequently and felt more depressed and angry than never smokers, but not former smokers. Whereas cravings for starchy foods and some mood states may be characteristic of women who are likely to smoke, more frequent cravings for fat among smokers is related to smoking per se. Similarly, obese women craved high fats more frequently than nonobese women and depression symptoms were intensified with increasing body weights. We hypothesize that the overlapping neuroendocrine alterations associated with obesity and smoking and the remarkable similarities in food cravings and mood states between women who smoke and women who are obese suggest that common biological mechanisms modulate cravings for fat in these women.
Identification of a conserved F-box protein 6 interactor essential for endocytosis and cytokinesis in fission yeast
Authors: Jourdain Isabelle , Spielewoy Nathalie , Thompson James , Dhut Susheela , Yates John R. , Toda Takashi
Published: February 2009

The F-box domain is a degenerated motif consisting of ∼40 amino acid residues that specifically bind Skp1, a core component of the SCF (Skp1-Cdc53/Cullin 1-F-box protein) ubiquitin ligase. Recent work, mainly performed in budding yeast, indicates that certain F-box proteins form non-SCF complexes together with Skp1 in the absence of cullins and play various roles in cell cycle and signalling pathways. However, it is not established whether these non-SCF complexes are unique to budding yeast or common in other eukaryotes. In the present paper, using TAP (tandem affinity purification) coupled to MudPIT (Multidimensional Protein Identification Technology) analysis, we have identified a novel conserved protein, Sip1, in fission yeast, as an interacting partner of an essential F-box protein Pof6. Sip1 is a large HEAT (huntingtin, elongation factor 3, the PR65/A subunit of protein phosphatase 2A and the lipid kinase Tor)-repeats containing protein (217 kDa) and forms a complex with Pof6 and Skp1. This complex does not contain cullins, indicating that it is a novel non-SCF complex. Like Pof6 and Skp1, Sip1 is essential for cell viability and temperature-sensitive sip1 mutants display cell division arrest as binucleate cells with septa. Sip1 localizes to the nucleus and dynamic cytoplasmic dots, which are shown in the present study to be endocytic vesicles. Consistent with this, sip1 mutants are defective in endocytosis. Furthermore, towards the end of cytokinesis, constriction of the actomyosin ring and dissociation of type II myosin and septum materials are substantially delayed in the absence of functional Sip1. These results indicate that the conserved Sip1 protein comprises a novel non-SCF F-box complex that plays an essential role in endocytosis, cytokinesis and cell division.
Two distinct signalling cascades target the NF-κB regulatory factor c-IAP1 for degradation
Authors: Csomos Rebecca A. , Wright Casey W. , Galbán Stefanie , Oetjen Karolyn A. , Duckett Colin S.
Published: February 2009

c-IAP1 (cellular inhibitor of apoptosis 1) has recently emerged as a negative regulator of the non-canonical NF-κB (nuclear factor κB) signalling cascade. Whereas synthetic IAP inhibitors have been shown to trigger the autoubiquitination and degradation of c-IAP1, less is known about the physiological mechanisms by which c-IAP1 stability is regulated. In the present paper, we describe two distinct cellular processes that lead to the targeted loss of c-IAP1. Recruitment of a TRAF2 (tumour necrosis factor receptor-associated factor 2)–c-IAP1 complex to the cytoplasmic domain of the Hodgkin's/anaplastic large-cell lymphoma-associated receptor, CD30, leads to the targeting and degradation of the TRAF2–c-IAP1 heterodimer through a mechanism requiring the RING (really interesting new gene) domain of TRAF2, but not c-IAP1. In contrast, the induced autoubiquitination of c-IAP1 by IAP antagonists causes the selective loss of c-IAP1, but not TRAF2, thereby releasing TRAF2. Thus c-IAP1 can be targeted for degradation by two distinct processes, revealing the critical importance of this molecule as a regulator of numerous intracellular signalling cascades.
Cross Sections for Electron Collisions with Oxygen Molecules
Authors: Itikawa Yukikazu
Published: February 2009

Cross section data are collected and reviewed for electron collisions with oxygen molecules. Included are the cross sections for total and elastic scatterings, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, electron attachment, and emission of radiations. For each process, the recommended values of the cross sections are presented, when possible. The literature has been surveyed through the end of 2007.
Reference Correlations for Thermophysical Properties of Liquid Water at 0.1MPa
Authors: Pátek Jaroslav , Hrubý Jan , Klomfar Jaroslav , Součková Monika , Harvey Allan H.
Published: February 2009

Simple but highly accurate correlations have been developed for the thermodynamic properties (including density, heat capacity, and speed of sound), viscosity, thermal conductivity, and static dielectric constant of liquid water as a function of temperature at a pressure of 0.1MPa. The calculations may be simply extended to a pressure range from the saturation pressure to 0.3MPa. The temperature range covered in most cases is from 253.15to383.15K; this includes some temperatures where liquid water is metastable. These correlations are designed to reproduce the best available data, which in most cases are described by formulations issued by the International Association for the Properties of Water and Steam (IAPWS). The equations presented here are simple enough to be used in applications such as spreadsheets. They provide a convenient alternative to the more complicated IAPWS formulations in cases where only liquid properties at near-atmospheric pressure are of interest without increasing the uncertainty beyond that of the more complex formulations.
To enhance the efficiency of a power supply circuit by the use of Fe–P–B–Nb-type ultralow loss glassy metal core
Authors: Matsumoto H. , Urata A. , Yamada Y. , Makino A.
Published: February 2009

The inductor in a power supply is required to be capable of dealing satisfactorily with the high-current supply and to improve the power loss characteristic. A novel glassy metal powder with a chemical composition Fe77P7B13Nb3 features both a high saturated magnetic flux density of 1.3 T and a low coercive force of 2.0 A/m, which has a stable amorphous structure suitable for glassy metal composite cores. Hence there is no magnetic saturation even under a high-current supply, and it is confirmed to have significantly low magnetic loss resulting from the low coercive force. As a result of using the glassy metal alloy Fe77P7B13Nb3 powder in an inductor core, we have achieved improvement in power supply efficiency by up to roughly 2.0%. Moreover, the reduction in the standby power requirement by the improvement in the power supply efficiency in the low load current case, where the core loss occupies a high ratio in the entire loss, can be expected. Additionally, heat generation in a core is suppressed by using the low loss powder, and it becomes easy to design a temperature rise in the entire power supply circuit.
Unusual magnetic behavior of SiCN/multiwalled carbon nanotubes nanocomposites
Authors: Francis A. , Riedel R.
Published: February 2009

Multiwalled carbon nanotubes (MWCNTs) have been dispersed homogeneously throughout a preceramic polysilazane matrix. The homogenized mixture was then warm pressed and subsequently pyrolyzed in Ar atmosphere at 1100  °C, yielding an amorphous silicon carbonitride (SiCN)/MWCNT nanocomposite. The hysteresis loop of the 5 vol % CNT/SiCN composite revealed a ferromagneticlike behavior up to 5000 Oe and a semiconductinglike feature at a higher applied field. The magnetic behavior of CNT-rich composites is due mainly to defects and to the interaction between the nanotubes and the SiCN matrix, which is indicated by a shift in the G and D bands of graphitic carbon as determined by Raman spectroscopy.
Calculations for the band lineup of strained InxGa1−xN/GaN quantum wells: Effects of strain on the band offsets
Authors: Das Tapas , Kabi Sanjib , Biswas Dipankar
Published: February 2009

Band lineup is one of the most important parameters associated with carrier confinement in heterostructures. Relations for computing the band lineups of InxGa1−xN based heterostructures have been developed. The band positions for InxGa1−xN/GaN heterointerfaces are calculated from the equations developed, which directly corelate the positions of the bands with the band gap of InN and strain at the interface. The strains are calculated from the In mole fractions and lattice constants. The parameters implicitly involved are the elastic stiffness constants (C11 and C12), the hydrostatic deformation potential of the conduction band (a′), and the hydrostatic deformation potential (a) and shear deformation potential (b) for the valence band. Computations have been carried out for different reported band gaps of InN. The effects of strain become prominent as the mole fraction of In increases, changing the band offset ratio.
Anisotropic magnetoresistance in biphase microwires
Authors: Infante G. , Merazzo K. J. , Badini-Confalonieri G. A. , Batallán F. , Vázquez M.
Published: February 2009

The magnetic properties and anisotropic magnetoresistance behavior of biphase microwires with an amorphous FeSiB nucleus are presented. The existence of an external CoNi magnetic layer is shown to modify the magnetoresistive response of the nucleus material by changing the internal anisotropies via magnetoelastic coupling. A careful control of the production parameters allows tailoring of the magnetic properties.
An approach to understand the effect of interlayer coupling in composite media using anomalous Hall effect measurement
Authors: Das Sarbanoo , Tanahashi Kiwamu , Suzuki Hiroyuki
Published: February 2009

Anomalous Hall effect measurement under a tilted magnetic field was applied to investigate the interlayer exchange coupling between the Co–Cr–Pt–SiO2 and Co–Cr–Pt layers of a composite perpendicular medium. The tilt of magnetization under the application of a tilted field detected selectively from the anomalous Hall voltage characteristics of the Co–Cr–Pt layer was influenced by the interlayer coupling effect. A magnetic anisotropy field term for the Co–Cr–Pt layer derived from the magnetization tilt characteristics increased with decreasing thickness of a spacer in between Co–Cr–Pt–SiO2 and Co–Cr–Pt layers, indicating the effect of increased interlayer exchange coupling.
Predicted half-metallicity with no net magnetization in Ca0.75Cr0.25As from a first-principles study
Authors: Lee Jae Il , Białek Beata , Kim Miyoung
Published: February 2009

The results of a first-principles study of the magnetic and half-metallic properties of ordered Ca-Cr-As alloy with zinc-blende like structure are presented. The full-potential linearized augmented plane wave method is used in order to resolve the electronic structure of CaxCr1−xAs alloy, in which concentration of Ca atoms varies from 25% to 75% (x=0.25,0.5,0.75). The obtained results indicate that all the investigated compounds are half-metallic with magnetic moment determined by the Ca concentration. Particularly, it is found that Ca0.75Cr0.25As is a half-metallic antiferromagnet with no net magnetization.
Anomalous temperature dependence of the magnetization in La0.84Sr0.16MnO3
Authors: Maryško M. , Savosta M. M. , Jirák Z. , Novák P.
Published: February 2009

The superconducting quantum interference device (SQUID) magnetization measurements have been performed on single crystal manganites La1−xSrxMnO3 (x=0.16;0.17) previously studied by the NMR method. For the x=0.16 sample an anomaly in the temperature dependence of the saturation magnetization at T1≈130 K is observed, which manifests itself as a cusp in dm/dT. This temperature lying well below the metal-insulator transition at TMI=157 K seems to correspond to an orbital ordering temperature Too indicated also by the decrease in the low field FC susceptibility. The observed anomaly, which is also reproduced in the temperature dependence of the NMR frequency, is ascribed to a continual decrease in the exchange interaction within the temperature interval 60 K and the difference between TMI and Too to an inherent inhomogeneity in Sr concentration. The relative SQUID magnetizations are compared with the NMR values.
Synthesis and magnetostriction of TbxPr1−x(Fe0.8Co0.2)1.9 cubic Laves alloys
Authors: Shi Y. G. , Tang S. L. , Yu J. Y. , Zhai L. , Zhang X. K. , Du Y. W. , Yang C. P.
Published: February 2009

Polycrystalline magnetostrictive alloys TbxPr1−x(Fe0.8Co0.2)1.9 (0≤x≤0.4) which cannot be obtained under normal pressure were synthesized by high-pressure annealing. Measurements of crystal structure, Curie temperature, magnetization, and magnetostriction were made on TbxPr1−x(Fe0.8Co0.2)1.9 alloys. X-ray diffraction results show that the alloys exhibit C15 cubic Laves phase with MgCu2-type structure. The lattice parameter decreases with increasing Tb concentration, while the Curie temperature increases. Because of the antiparallel magnetic moment of Tb and Pr, the saturation magnetization decreases with increasing Tb concentration. The magnetostriction of Tb0.05Pr0.95(Fe0.8Co0.2)1.9 shows a peak at low magnetic fields, while that of Tb0.4Pr0.6(Fe0.8Co0.2)1.9 exhibits a minimum in the whole range of magnetic fields.
Exploring hysteresis and energy dissipation in single-molecule force spectroscopy
Authors: Tshiprut Zion , Urbakh Michael
Published: February 2009

We propose an analytical approach to describe the active rebinding and force hysteresis observed in single-molecule pulling experiments. We derive equations for dependences of the measured quantities on the properties of molecular potential, effective stiffness of the pulling spring, and the pulling velocity. The calculations predict that the energy dissipated per an unbinding-rebinding cycle strongly increases with the steepness of the molecular potential and with decreasing the spring stiffness. A comparison of analytical results with Langevin simulations shows that the scaling relations for the barrier heights and most probable forces are more accurate in the case of active rebinding than for unbinding. Our consideration demonstrates that simultaneous analysis of probability density functions for unbinding and rebinding forces improves essentially the accuracy of retrieval information on intrinsic parameters of the molecular complex from the force measurements.
Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy
Authors: Elles Christopher G. , Rivera Christopher A. , Zhang Yuyuan , Pieniazek Piotr A. , Bradforth Stephen E.
Published: February 2009

Two-photon absorption (2PA) spectroscopy in the range from 7 to 10 eV provides new insight on the electronic structure of liquid water. Continuous 2PA spectra are obtained via the pump-probe technique, using broadband probe pulses to record the absorption at many wavelengths simultaneously. A preresonance enhancement of the absolute 2PA cross section is observed when the pump-photon energy increases from 4.6 to 6.2 eV. The absorption cross section also depends on the relative polarization of the pump and probe photons. The variation of the polarization ratio across the spectrum reveals a detailed picture of the 2PA and indicates that at least four different transitions play a role below 10 eV. Theoretical polarization ratios for the isolated molecule illustrate the value of the experimental polarization measurement in deciphering the 2PA spectrum and provide the framework for a simple simulation of the liquid spectrum. A more comprehensive model goes beyond the isolated molecule picture and connects the 2PA spectrum with previous one-photon absorption, photoelectron, and x-ray absorption spectroscopy measurements of liquid water. Previously unresolved, overlapping transitions are assigned for the first time. Finally, the electronic character of the vertical excited states is related to the energy-dependent ionization mechanism of liquid water.
Intersubband optical absorption in a step asymmetric semiconductor quantum well driven by a terahertz field
Authors: Zhu Hai-Yan , Zhang Tong-Yi , Zhao Wei
Published: February 2009

The nonlinear optical absorption in a three-subband step asymmetric semiconductor quantum well driven by a strong terahertz (THz) field is investigated theoretically by employing the intersubband semiconductor-Bloch equations. We show that the optical absorption spectrum strongly depends on the intensity, frequency, and phase of the pump THz wave. The strong THz field induces THz sidebands and Autler-Townes splitting in the probe absorption spectrum. Varying the pump frequency can bring not only the new absorption peaks but also the changing of the energy separation of the two higher-energy levels. The dependence of the absorption spectrum on the phase of the pump THz wave is also very remarkable.
Monte Carlo simulation for excessive Balmer line broadening generated by transport of fast H Atoms in an abnormal glow discharge
Authors: Cvetanović N. , Obradović B. M. , Kuraica M. M.
Published: February 2009

Monte Carlo code for fast hydrogen atom transport and generating of excessively Doppler broadened profiles based on the collision model is presented. Results for the initial monoenergetic atom beam and for a more realistic energy distribution of H atoms are reported. Line profiles obtained from the simulation are compared to our experimentally obtained data. Initial energy distribution for atoms is approximately calculated from the measured line profiles while the initial angle distribution was taken to be cosine. Balmer alpha intensity was found to exponentially decay in the negative glow region, which concurs with the experimental results. These agreements between the simulation and experiment support the collision model for excessive line broadening.