bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of sea ice on primary production in the Southern Ocean: A satellite perspective
Authors: Smith Walker O. , Comiso Josefino C.
Published: May 2008

Sea ice in the Southern Ocean is a major controlling factor on phytoplankton productivity, but the relationship is modified by regional differences in atmospheric and oceanographic conditions. We used the phytoplankton biomass, photosynthetically active radiation (PAR), and cloud cover data from Sea‐viewing Wide Field of View Sensor (SeaWiFS), ice concentrations data from Special Sensor Microwave Imager (SSM/I) and Advanced Microwave Scanning Radiometer‐EOS (AMSR‐E), sea‐surface temperature data from advanced very high resolution radiometer (AVHRR), and a vertically integrated model to estimate primary productivity south of 60°S. We also selected six areas within the Southern Ocean and analyzed the variability of the primary productivity and trends through time. We found substantial interannual variability in productivity from 1997 to 2005 in all regions of the Southern Ocean, and this variability appeared to be driven in large part by ice dynamics. The most productive regions of Antarctic waters were the continental shelves, and no sustained blooms occurred in waters of greater depth (>1000 m). We suggest that this is due to the slightly greater mixed layer depths found in waters off the continental shelf, and that the interactive effects of iron and irradiance result in the limitation of phytoplankton biomass over large regions of the Southern Ocean. Annual productivity of the Southern Ocean averaged 23.65 g C m−2 a−1, but yearly means for the years between 1998 and 2004 ranged from 22.10 to 25.49 g C m−2 d−1, respectively. Annual primary productivity over the entire Southern Ocean appears to have increased significantly since 1998, and much of this increase was confined to the months of January and February. Causes for this trend are presently unclear.
Thickness distribution of Antarctic sea ice
Authors: Worby Anthony P. , Geiger Cathleen A. , Paget Matthew J. , Van Woert Michael L. , Ackley Stephen F. , DeLiberty Tracy L.
Published: May 2008

Ship‐based observations are used to describe regional and seasonal changes in the thickness distribution and characteristics of sea ice and snow cover thickness around Antarctica. The data set comprises 23,373 observations collected over more than 2 decades of activity and has been compiled as part of the Scientific Committee on Antarctic Research (SCAR) Antarctic Sea Ice Processes and Climate (ASPeCt) program. The results show the seasonal progression of the ice thickness distribution for six regions around the continent together with statistics on the mean thickness, surface ridging, snow cover, and local variability for each region and season. A simple ridge model is used to calculate the total ice thickness from the observations of level ice and surface topography, to provide a best estimate of the total ice mass, including the ridged component. The long‐term mean and standard deviation of total sea ice thickness (including ridges) is reported as 0.87 ± 0.91 m, which is 40% greater than the mean level ice thickness of 0.62 m. Analysis of the structure function along north/south and east/west transects revealed lag distances over which sea ice thickness decorrelates to be of the order of 100–300 km, which we use as a basis for presenting near‐continuous maps of sea ice and snow cover thickness plotted on a 2.5° × 5.0° grid.
Quantifying Antarctic Bottom Water and North Atlantic Deep Water volumes
Authors: Johnson Gregory C.
Published: May 2008

A near‐global census of Antarctic Bottom Water (AABW) and North Atlantic Deep Water (NADW) is essayed through a nonnegative least squares analysis of conservative and quasi‐conservative seawater properties. AABW thickness generally decreases from south to north, modulated by ocean bathymetry. Likewise, NADW thickness generally decreases from north to south in the Atlantic Ocean. NADW dominates below the thermocline of the Atlantic Ocean at least as far south as the subtropical gyre of the South Atlantic, with a lesser, but still significant, influence around the entire Antarctic Circumpolar Current, in the Indian Ocean, and in the Pacific Ocean. However, in the Pacific and Indian oceans, AABW dominates below the thermocline. In addition, measurable quantities of AABW reach into the abyssal North Atlantic on both sides of the mid‐Atlantic Ridge. The census results suggest that AABW occupies roughly twice the volume of NADW in the three main oceans, and that AABW is in contact with roughly twice the area of the deep main ocean floor compared with NADW. However, these results are somewhat sensitive to choices of water masses, their values of seawater properties, and the weightings of the seawater properties used in the analysis.
Validation of Tropospheric Emission Spectrometer ozone profiles with aircraft observations during the Intercontinental Chemical Transport Experiment–B
Authors: Richards Nigel A. D. , Osterman Gregory B. , Browell Edward V. , Hair Johnathan W. , Avery Melody , Li Qinbin
Published: May 2008

The Tropospheric Emission Spectrometer (TES) is an infrared instrument that was launched on board NASA's Aura satellite in 2004. TES is the first instrument to provide vertical information on tropospheric ozone while simultaneously measuring CO on a global basis. Before they may be used for scientific study, TES profiles must first be validated to determine if there are any systematic biases present. In this study we present a validation of TES tropospheric ozone using airborne differential absorption lidar (DIAL) profiles obtained during the Intercontinental Chemical Transport Experiment–B (INTEX‐B) campaign, which took place during March–May 2006. During INTEX‐B the NASA DC‐8 aircraft conducted several flights, which allowed the DIAL instrument to obtain ozone profile measurements that were spatially coincident with TES special observations in three different geographical regions. Here we present comparisons of TES and DIAL tropospheric ozone profiles that show that, on average, TES exhibits a small positive bias in the troposphere of 5–15%. We also examine the use of in situ profile observations for the validation of TES tropospheric ozone, and we find these to be of most use in clean regions where the background ozone field is homogeneous.
A system for operational aerosol optical depth data assimilation over global oceans
Authors: Zhang Jianglong , Reid Jeffrey S. , Westphal Douglas L. , Baker Nancy L. , Hyer Edward J.
Published: May 2008

In this study, we present an aerosol data assimilation system destined for operational use at the Fleet Numerical Meteorological and Oceanographic Center (FNMOC). The system is an aerosol physics version of the Naval Research Laboratory (NRL) Atmospheric Variational Data Assimilation System (NAVDAS) that is already operational. The purpose of this new system, NAVDAS‐Aerosol Optical Depth (NAVDAS‐AOD) is to improve the NRL Aerosol Analysis and Prediction System (NAAPS)'s forecasting capability by assimilating observational data sources with NAAPS forecast fields. This will allow for not only improved aerosol forecasting but also for dramatically enhanced global scale research capabilities for the study of aerosol‐meteorology interaction. NAVDAS‐AOD assimilates a newly developed over‐water Moderate‐Resolution Imaging Spectroradiometers (MODIS) level 3 aerosol product with NAAPS. This paper is the second in a series which describes NRL's program to realistically monitor global aerosol distributions. Here we explain the reasons and procedures for constructing the over‐water level 3 MODIS aerosol product, describe the theoretical basis for NAVDAS‐AOD, and provide a thorough statistical error analysis for both the MODIS observations and the NAAPS model background fields that are critical to aerosol data assimilation. Using 5 months of analysis, our study shows that by carefully screening over‐water satellite observations to ensure only the best quality data are used in the aerosol assimilation process, the NAVDAS‐AOD can significantly improve the NAAPS global aerosol optical depth analysis as well as improve the aerosol forecast skill.
Comparison of aerosol extinction coefficients, surface area density, and volume density from SAGE II and in situ aircraft measurements
Authors: Reeves J. M. , Wilson J. C. , Brock C. A. , Bui T. P.
Published: May 2008

Aerosol size distributions measured in the lower stratosphere by the University of Denver's focused cavity aerosol size spectrometer (FCAS) were used to calculate aerosol extinction coefficients, surface area densities, and volume densities for comparison with the Stratospheric Aerosol and Gas Experiment (SAGE) II version 6.20 data products. Profiles from ten high‐altitude aircraft flights, ranging approximately 8.5 to 20.5 km altitude, are compared with nearby SAGE II occultation events. Nine of the flights date from late 1995 through 1997, and one is from early 2004. Extinctions are found to agree within instrumental uncertainties except at 386 nm below 17 km, where the SAGE II values are systematically low despite their large errors. Above 12 km, where the comparisons are statistically significant, the SAGE II volume density is about 35% lower than the FCAS measurements, though just within combined uncertainties, while the SAGE II surface area density is low compared to FCAS by a factor of 1.5 to 3. The limitations of principal component analysis may account for up to two thirds of the discrepancy in surface area density.
Fe oxidation processes at Meridiani Planum and implications for secondary Fe mineralogy on Mars
Authors: Tosca Nicholas J. , McLennan Scott M. , Dyar M. Darby , Sklute Elizabeth C. , Michel F. Marc
Published: May 2008

Fe oxidation processes may have occurred during groundwater‐mediated diagenesis in Meridiani Planum sediments. To address this question, melanterite oxidation experiments were conducted at epsomite saturation as a function of pH. Results show that schwertmannite is initially formed from acidic Fe oxidation and that its formation and aging to mixtures of jarosite and nanocrystalline goethite is strongly controlled by pH over the range ∼2.0–4.0. The pH is controlled in turn by Fe oxidation and Fe3+ hydrolysis. In one 77‐d oxidation experiment, nanocrystalline hematite was tentatively identified by Mössbauer spectroscopy. Accordingly, aging experiments with synthetic nanocrystalline goethite were conducted (1) to further resolve the formation mechanisms of Fe‐phases identified from oxidation experiments and (2) to test whether low water activity (aw) controls the thermodynamically favored goethite to hematite transition at low temperature. Mössbauer spectroscopy and total X‐ray scattering show no observable changes after 4 months of aging, and instead, these results point to a jarosite precursor for the tentatively identified hematite. On the basis of these results, we suggest that the oxidation and maturation of initially formed Fe2+‐bearing saline minerals may account in large part for the distribution of secondary Fe minerals at the Martian surface, contributing to the association of Fe oxides and Mg/Ca sulfates observed from orbital surface analyses. We hypothesize that oxidation of Fe2+ sulfates at low temperature could account for sustained diagenetic acidity in addition to much of the observed Fe mineralogy in Meridiani Planum outcrop rocks. The origin of the gray crystalline hematite at Meridiani, however, is deserving of further experimental work to test this mechanism.
Quantitative forecast of relativistic electron flux at geosynchronous orbit based on low‐energy electron flux
Authors: Turner Drew L. , Li Xinlin
Published: May 2008

A strong correlation between the behavior of low‐energy (tens to hundreds of keV) and high‐energy (>1 MeV) electron fluxes measured at geosynchronous orbit has been discussed, and this correlation is further enhanced when a time offset is taken into account. A model has been developed incorporating this delay time between similar features in low‐ and high‐energy electron fluxes to forecast the logarithm of daily averaged, 1.1–1.5 MeV electron flux at geosynchronous orbit several days in advance. The model uses only the current and previous days' daily averaged fluxes of low‐ and high‐energy electrons as input. Parameters in the model are set by optimizing prediction efficiency (PE) for the years 1995–1996, and the optimized PE for these 2 years is 0.81. The model is run for more than one full solar cycle (1995–2006), and it consistently performs significantly better than a simple persistence model, where tomorrow's forecasted flux is simply today's value. Model results are also compared with an inward radial diffusion forecast model, in which the diffusion coefficient is a function of solar wind parameters. When the two models are combined, the resulting model performs better overall than each does individually.
Thermochronometer record of central Andean Plateau growth, Bolivia (19.5°S)
Authors: Barnes J. B. , Ehlers T. A. , McQuarrie N. , O'Sullivan P. B. , Tawackoli S.
Published: May 2008

Quantifying the timing, magnitude, and rates of exhumation and deformation across the central Andes is a prerequisite for understanding the history of plateau rise. We present 23 new apatite and zircon fission track thermochronometer samples to chronicle the exhumation and deformation across the entire (∼500 km) Andean fold‐thrust belt at ∼19.5°S in Bolivia. Exhumation and deformation are constrained with inverse thermal modeling of the thermochronometer data, regional stratigraphy, geothermal gradients, and mass deficits inferred from a balanced section. Results suggest the following: (1) Initial exhumation of the Eastern Cordillera (EC) fore‐thrust and back‐thrust belts began in the late Eocene to early Oligocene (27–36 Ma) and continued in a distributed manner in the late Oligocene to early Miocene (19–25 Ma). Interandean zone (IA) exhumation began 19–22 Ma, followed by a third pulse of exhumation (11–16 Ma) in the EC back‐thrust belt and initial cooling in the westernmost Subandes (SA) 8–20 Ma. Finally, exhumation propagated eastward across the SA during the late Mio‐Pliocene (2–8 Ma). (2) Exhumation magnitudes are spatially variable and range from maximums of <8 km in the EC fore‐thrust belt to average values of ∼4–7 km across the EC, ∼2.5–3 km in the Altiplano, ∼4–6 km in the IA, and ∼3 km in the SA. (3) Exhumation rates range from ∼0.1 to 0.2 mm/a in the EC, from ∼0.1 to 0.6 mm/a in the IA, and from ∼0.1 to 0.4 mm/a to locally 1.4 mm/a or more in the eastern SA. We synthesize similar constraints with sediments throughout Bolivia and characterize plateau development by (1) distributed deformation throughout the Altiplano and EC regions from ∼20 to 40 Ma with minor deformation continuing until ∼10 Ma, (2) contemporaneous cessation of most EC deformation and exhumation of the IA ∼20 Ma implying establishment of the modern plateau width with significant, but unknown crustal thickness and elevation shortly thereafter by ∼15–20 Ma, and (3) dominantly eastward propagation of deformation from the IA since ∼20 Ma with minor out‐of‐sequence deformation in the central to eastern SA.
Pacific trench motions controlled by the asymmetric plate configuration
Authors: Nagel Thorsten J. , Ryan William B. F. , Malinverno Alberto , Buck W. Roger
Published: May 2008

We present a novel explanation for absolute trench‐normal motions of slabs surrounding the Pacific. Rapid subduction‐zone retreat on the eastern side of the Pacific and slow advance in the west can result from the large‐scale asymmetric plate configuration. We use simple fluid dynamics to explain the mechanical background of this hypothesis, and we use the results of a simple finite difference scheme to estimate the effect on trench motion velocities. The hypothesis is based on two key assumptions. First, we follow the concept of plate‐scale horizontal counterflow in the asthenosphere driven by accretion of asthenosphere into lithosphere and by plate motion. Second, we assume that horizontally wide slabs without large slab windows drift passively in the mantle flow field and do not retreat as a result of flow around the slab. If the asthenosphere transfers flow‐related horizontal shear stress into deeper levels of the mantle, an asymmetry in the plate configuration leads to different net pressure forces on the two slabs and thus affects the retreat behavior. In an ocean with an asymmetric ridge position, the slab of the smaller plate should retreat faster than the slab of the large plate, which may even advance. Also, the domain of a slower moving plate should collapse faster than the domain of the faster plate. Our model explains the counterintuitive negative correlation between slab age and retreat velocity observed in the Pacific. It also accords with the topographic asymmetry of the ridge flanks along the Pacific rise.
Late Quaternary activity of the Scorciabuoi Fault (southern Italy) as inferred from morphotectonic investigations and numerical modeling
Authors: Caputo Riccardo , Salviulo Luigi , Bianca Marcello
Published: May 2008

Following a detailed morphotectonic analysis of the fluvial terraces of the Sauro River (Basilicata, southern Italy), the present research documents for the first time the late Quaternary tectonic activity of the Scorciabuoi Fault and discusses its inferred seismogenic potential. On the basis of both remote sensing techniques and detailed field investigations, four fill terraces have been recognized and mapped along the Sauro Valley showing differential cumulative displacements across the fault. These terraces are genetically correlated with four highstand sea level periods. Following stratigraphic and geological age constraints and on the basis of the correlation with a sequence of marine and fluvial terraces characterizing the lower Agri Valley, the Sauro terraces likely formed between 80 (or 100) ka and Present. The inferred long‐term slip rate of the Scorciabuoi Fault ranges between 0.5 and 1.0 mm/a. Numerical simulations based on a crustal elastic deformation model also contribute to separate and tentatively quantify the regional uplift rate (∼1.0–1.4 mm/a) and to improve the overall reconstruction of the late Quaternary evolution of the area. The synergic but distinct roles played by eustatism, regional uplift, and faulting are eventually appreciated.
Three‐dimensional equatorial spread F modeling
Authors: Huba J. D. , Joyce G. , Krall J.
Published: May 2008

The Naval Research Laboratory (NRL) has developed a new three‐dimensional code to study equatorial spread F (ESF). The code is based on the comprehensive NRL 3D ionosphere model SAMI3 and includes a potential equation to self‐consistently solve for the electric field. The model assumes equipotential field lines so a 2D electrodynamic problem is considered. In this study a narrow wedge of the post‐sunset ionosphere is simulated. It is found that (1) bubbles can rise to ∼1600 km, (2) extremely steep ion density gradients can develop in both longitude and latitude, (3) upward plasma velocities approach 1 km/s, and (4) the growth time of the instability is ≃15 min. These results are shown to be consistent with radar and satellite observations.
Tropical cyclones in ERA‐40: A detection and tracking method
Authors: Kleppek S. , Muccione V. , Raible C. C. , Bresch D. N. , Koellner‐Heck P. , Stocker T. F.
Published: May 2008

A tracking method for tropical cyclones (TCs) is presented and their characteristics for data sets with a lower horizontal resolution, e.g., the ERA‐40 Reanalysis data set from 1958 to 2001 are explored. The tracking method uses sea level pressure, relative vorticity and wind speed at 850 hPa, and vertical wind shear. The method, assessed in the Atlantic basin, identifies a realistic number of TCs. However, the ERA‐40 TCs compared with best track data from the U.S. National Hurricane Center are too weak to reach hurricane character, i.e., the tracked TCs do not show hurricanes of category three to five. Another caveat is that the life cycle of central pressure values is often not realistically reproduced by ERA‐40 TCs. To correct the life cycle of the central pressure, a two‐step statistical downscaling approach is applied to the ERA‐40 TCs which strongly improves the finding of major hurricanes.
A rare SAR11 fosmid clone confirming genetic variability in the ‘Candidatus Pelagibacter ubique’ genome
Authors: Gilbert Jack A , Mühling Martin , Joint Ian
Published: May 2008

A sequence analysis is described of a fosmid clone from a coastal marine metagenomic library that contains a 16S rRNA gene with high sequence similarity to that of the SAR11 bacterium ‘Candidatus Pelagibacter ubique’ HTCC1062. The sequence of the fosmid clone was 32 086 bp in length and contained 23 187 bp of the 48-kb hyper-variable region 2 (HVR2) present in the genome of ‘Cand. P. ubique’. However, half of the sequences within the HVR2 region of the fosmid clone show little sequence similarity to or have no representative homologues in the genome sequence of ‘Cand. P. ubique’ HTCC1062. Given their putative functions, the acquisition of these genes suggests that SAR11 could harbour more diverse phenotypes than represented by the 16S rRNA taxonomy. Variation in SAR11 genomes from different locations might explain why SAR11 is abundant in so many diverse marine provinces.
Natural evidence for garnet-spinel transition (GST) in the Earth's mantle
Authors: Su BenXun
Published: May 2008

This study based on compiled world-wide garnet peridotite data confirms the GST in high P and T conditions, which was obtained from Al-free experimental system (MgO-Cr~2~O~3~-SiO~2~) by Klemme (2004). A new spinel-phase peridotite zone, garnet peridotite discontinuous zone, is defined, and another GST, although no experimental data, is principally and presumably proposed to exist. The garnet inclusion-bearing spinel harzburgite from Lashaine (Tanzania) provides the first evidence for the existence of ultra-high spinel zone and is explained as recrystallized minerals hosting the interacted residue of ancient oceanic lithosphere subducted into the great depth of more than 220km. These previously unexpected findings are generating great challenges to phase transition in extreme conditions and to our understanding of layered-structure of the Earth. In addition, coexistent five-phase peridotite is suggested to be naturally useful tool to constrain the GST.
Parental Perceptions of Overweight Counseling in Primary Care: The Roles of Race/ethnicity and Parent Overweight
Authors: Taveras Elsie M. , Gortmaker Steven L. , Mitchell Kathleen F. , Gillman Matthew W.
Published: May 2008

Objective: To examine parental perceptions of primary care efforts aimed at childhood obesity prevention

Methods and Procedures: We interviewed 446 parents of children, aged 2–12 years, with an age‐ and sex‐specific BMI ≥85th percentile; interviews occurred within 2 weeks of their child's primary care visit. We assessed parental ratings of the nutrition and physical activity advice received. Using children's clinical heights and weights and parents' self‐reported heights and weights, we classified children into three categories: BMI 85th–94th percentile without an overweight parent, BMI 85th–94th percentile with an overweight parent (adult BMI ≥25 kg/m2), and BMI ≥95th percentile.

Results: In multivariate analyses, compared to parents of children with BMI ≥95th percentile, overweight parents with children whose BMI was 85th–94th percentile were more likely to report receiving too little advice on nutrition and physical activity (odds ratio (OR) 3.05; 95% confidence interval (CI) 1.49, 6.25) and to rate as poor or fair the quality of advice they received (OR 2.23; 95% CI 1.18, 4.24). Independently, African‐American (OR 2.55; 95% CI 1.18, 5.51) and Hispanic/Latino (OR 2.78; 95% CI 1.27, 6.10) parents were more likely than white parents to rate as poor or fair the quality of advice they received.

Discussion: Parental overweight is associated with low subjective ratings of overweight counseling in pediatric primary care. Our findings of poorer perceived quality among racial/ethnic minority parents need further investigation.
Caspase‐mediated Degradation of PPARγ Proteins in Adipocytes
Authors: He Fang , Doucet Julie A. , Stephens Jacqueline M.
Published: May 2008

Objective: Peroxisome proliferator‐activated receptor γ (PPARγ) is a transcription factor that plays an important role in adipocyte gene expression. Previous studies from our laboratory and others have shown that PPARγ can be ubiquitin modified and targeted to the proteasome for degradation in response to transcriptional activation. In this study, we determined whether other degradation pathways contributed to the tumor necrosis factor α (TNFα)–induced degradation of PPARγ proteins in 3T3‐L1 adipocytes.

Methods and Procedures: In these studies, 3T3‐L1 cells were studied by performing subcellular fractionations and western blotting after various TNFα treatments. Whole tissue extracts from rat adipose tissue were also used to examine PPARγ degradation.

Results: We observed that TNFα can induce a caspase‐mediated degradation of PPARγ proteins in the presence of cycloheximide. The caspase‐mediated degradation of both PPARγ1 and PPARγ2 resulted in the generation of a specific 44‐kd cleavage product. The specific cleavage product was unaffected by proteasome inhibitors, but was repressed by a general caspase inhibitor. Use of several specific caspase inhibitors revealed that caspase‐1 was activated following treatment with TNFα and cycloheximide (CH), and inhibition of caspase‐1 blocked the cleavage of PPARγ proteins in cultured adipocytes. In addition, a similar PPARγ degradation product was observed in rodent adipose tissue.

Discussion: In summary, this is the first study to demonstrate that PPARγ levels can be modulated by caspase activity.
Raised CRP Levels in Obese Patients: Symptoms of Depression Have an Independent Positive Association
Authors: Dixon John B. , Hayden Melissa J. , Lambert Gavin W. , Dawood Tye , Anderson Margaret L. , Dixon Maureen E. , O'Brien Paul E.
Published: May 2008

Background: Depression and obesity, the two common ailments of modern society, are associated with increased risk of coronary artery disease and raised C‐reactive protein (CRP) levels. Are the effects of depression and obesity related or do they influence CRP levels independently?

Objective: In 493 consecutive patients presenting for obesity surgery, we explored the relationship between symptoms of depression and raised CRP levels after controlling for confounding factors.

Methods and Procedures: Depression was measured using the Beck Depression Inventory (BDI). Confounding variables were age, gender, BMI, waist and hip measures, smoking and alcohol habits, medications, biochemical measures of the metabolic syndrome, and indirect measures of insulin resistance. General linear regression sought variables independently associated with CRP levels.

Results: These patients had a BMI range from 31 to 91 kg/m2, participants age ranged from 14 to 71 years, and 76% were women. The median CRP concentration was 7.7 mg/l (interquartile range: 3.9–14), 40% had an abnormally raised concentration (>10 mg/l). The mean BDI score was 17.0 ± 9.0, indicating symptoms of moderate depression. We found five independent factors associated with raised CRP levels. In order of strength of association, these were: higher BMI (β = 0.36, P < 0.001), female gender (β = −0.19, P < 0.001), estrogen therapy (β = 0.18, P < 0.001), higher BDI score (β = 0.11, P = 0.01), and insulin resistance index (β = 0.11, P = 0.01), and with a combined R 2 = 0.24, (P < 0.001).

Discussion: In obese patients, symptoms of depression were associated with raised CRP levels after controlling for confounding variables. Obese women on estrogen therapy are at risk of high CRP levels.
LMNA mRNA Expression Is Altered in Human Obesity and Type 2 Diabetes
Authors: Miranda Merce , Chacón Matilde R. , Gutiérrez Cristina , Vilarrasa Nuria , Gómez Jose M. , Caubet Enric , Megía Ana , Vendrell Joan
Published: May 2008

Objective: The aim of this study was to analyze lamin A/C mRNA levels in abdominal subcutaneous adipose tissue in two conditions—obesity and type 2 diabetes—that share common inflammatory and metabolic features, and to assess their relationship with selected inflammatory and adipogenic genes.

Methods and Procedures: This is a cross‐sectional study involving 52 nondiabetic and 54 type 2 diabetes patients. Anthropometrical and analytical measurements (glycemic, lipidic, and inflammatory profiles) were performed, and mRNA expression was determined using real‐time PCR.

Results: Lamin A and C isoforms are expressed differentially. Lamin A/C mRNA levels were increased in obese and in type 2 diabetes patients. We also observed a strong relationship between both isoforms (B = 2.218, P < 0.001) and among lamin C mRNA expression and adipogenic (sterol‐responsive element binding protein‐1 (SREBP1c)) and inflammatory (interleukin‐6 (IL‐6)) markers (B = 0.854, P = 0.001, and B = 0.557, P < 0.001, respectively).

Discussion: These data suggest that lamin A/C may be involved in the adipocyte gene profile observed in obesity and type 2 diabetes.
Atomic Transition Probabilities of Aluminum. A Critical Compilation
Authors: Kelleher D. E. , Podobedova L. I.
Published: May 2008

This compilation is the second in a series of updates to Atomic Transition Probabilities, Sodium through Calcium, published in 1969 by Wiese et al. [Atomic Transition Probabilities, Vol. II, Vol. II: Sodium through Calcium, NSROS-NBS Vol. 2 (U.S. GPO, Washington, D.C., 1969)]. Atomic transition probabilities have been critically evaluated and compiled for about 5000 spectral lines of aluminum (nuclear charge Z=13). The cited values and their estimated uncertainties are based on our consideration of all available theoretical and experimental literature sources. All ionization stages (except for hydrogenic) are covered, and the data are presented in separate tables for each atom and ion. Separate listings are given for “allowed” (electric dipole) and “forbidden” (magnetic dipole plus electric and magnetic quadrupole) transitions. In each spectrum, lines are grouped into multiplets which are arranged in order of ascending lower- and upper-level energies, respectively. For each line, the emission transition probability Aki, the line strength S, and (for allowed lines) the absorption oscillator strength fik are given, together with the spectroscopic designation, the wavelength, the statistical weights, and the energy levels of the lower and upper states. The estimated relative uncertainties of the line strength are also indicated, as are the source citations. We include only those lines whose transition rates are deemed sufficiently accurate to qualify as reference values. Short introductions precede the tables for each ion.
IUPAC-NIST Solubility Data Series. 85. Transition and 12–14 Main Group Metals, Lanthanide, Actinide, and Ammonium Halates
Authors: Balarew Christo , Zagnit’ko E. V. , Eysseltova Jitka , Counioux Jean-Jacques
Published: May 2008

This paper is the fourth and final volume in the halate solubility series. The solubility data for halates of transition metals, lanthanides, actinides, ammonium, and metallic elements of the main groups 12–14 are reviewed. Where appropriate, binary, ternary, and multicomponent systems are critically evaluated. Most of the solubility results were obtained in water or aqueous solutions of electrolytes. The solubility in organic solvents and aqueous-organic solvent mixtures is also collected in this volume. All these data were critically examined for their reliability. The best values were selected on the basis of critical evaluations and presented in tabular form. Fitting equations and graphical plots are also provided. When numerical data were not reported in an original publication, they were read out from figures and digitized by the compilers. The quantities, units, and symbols used in this volume are in accord with IUPAC recommendations. We always reported the original data and, if necessary, transferred them into the IUPAC recommended units and symbols. The literature on the solubility data was researched through 2002. The halates of these metals play a role in industrial processes. For example, some halates are essential as catalysts, heat stabilizers, and blanching reagents for manufacturing polymer products such as textiles and resins. Some iodates are used in pyrotechnic compounds for weather modification and colored smoke generation. The nonlinear halate crystals are important in construction of optical devices.
IUPAC-NIST Solubility Data Series. 86. Ethers and Ketones with Water. Part 1. C2–C5 Ethers with Water
Authors: Góral Marian , Wiśniewska-Gocłowska Barbara
Published: May 2008

The mutual solubilities and related liquid-liquid equilibria of C2–C5 ethers with water are exhaustively and critically reviewed. Reports of experimental determination of solubility in ten chemically distinct binary systems that appeared in the primary literature prior to the end of 2006 are compiled. For three systems, sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a recently developed method based on the evaluation of all experimental data for a given series of ethers was used.
Cross Sections for Electron Collisions with Hydrogen Molecules
Authors: Yoon Jung-Sik , Song Mi-Young , Han Jeong-Min , Hwang Sung Ha , Chang Won-Seok , Lee BongJu , Itikawa Yukikazu
Published: May 2008

Cross section data have been compiled for electron collisions with hydrogen molecules based on 71 references. Cross sections are collected and reviewed for total scattering, elastic scattering, momentum transfer, excitations of rotational, vibrational, and electronic states, dissociation, ionization, emission of radiation, and dissociative attachment. For each process, the recommended values of the cross section are presented for use. The literature has been surveyed through the end of 2006.
IUPAC-NIST Solubility Data Series. 86. Ethers and Ketones with Water. Part 2. C6 Ethers with Water
Authors: Góral Marian , Wiśniewska-Gocłowska Barbara
Published: May 2008

The mutual solubilities and related liquid-liquid equilibria of C6 ethers with water are exhaustively and critically reviewed. Reports of experimental determination of solubility in binary systems that appeared in the primary literature prior to the end of 2006 are compiled. For four of the seven systems treated, sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a method based on the evaluation of all experimental data for a given series of ethers was used.
IUPAC-NIST Solubility Data Series. 86. Ethers and Ketones with Water. Part 3. C7–C14 Ethers with Water
Authors: Góral Marian , Wiśniewska-Gocłowska Barbara
Published: May 2008

The mutual solubilities and related liquid-liquid equilibria of nine binary systems of C7–C14 ethers with water are exhaustively and critically reviewed. Reports of experimental determination of solubility that appeared in the primary literature prior to the end of 2006 are compiled. For three systems, sufficient data are available to allow critical evaluation. All data are expressed as mass percent and mole fraction as well as the originally reported units. In addition to the standard evaluation criteria used throughout the Solubility Data Series, a method based on the evaluation of all experimental data for a given series of ethers was used.
Bursting characteristics of a neuron model based on a concept of potential with active areas
Authors: Nakajima Koji , Suenaga Shinya
Published: May 2008

We present various bursting wave forms that are obtained from a simple model of the Hodgkin–Huxley type. The model is a typical example whose characteristics can be discussed through the concept of potential with active areas. A potential function is able to provide a global landscape for dynamics of a model, and the dynamics are explained in relation to the disposition of the active areas on the potential. We obtain the potential functions and the active areas for the Hindmarsh–Rose model, the Morris–Lecar system, and the Hodgkin–Huxley system, and hence, we are able to discuss the common properties among these models based on the concept of potential with active areas.
Structural transitions in model β-sheet tapes
Authors: Bellesia Giovanni , Fedorov Maxim V. , Timoshenko Edward G.
Published: May 2008

We present a molecular-scale simulation study of the structural transitions between helicoidal, helical, and tubular geometries in supramolecular β-sheet tapes. Such geometries have been observed in different self-assembled amyloid systems (based on either natural or synthetic peptides) for which the β-sheet tapes represent the simplest fibrillar aggregates. A coarse-grained model for the β-sheet tapes is proposed, with chiral degrees of freedom and asymmetrical chemical properties, which provides a quantitative characterization of the structural transitions. A quantitative connection is established between the molecular properties and the elastic parameters of the supramolecular tapes.
Guided ion beam studies of the reactions of Con+ (n=1–18) with N2: Cobalt cluster mononitride and dinitride bond energies
Authors: Liu Fuyi , Li Ming , Tan Lin , Armentrout P. B.
Published: May 2008

The reactions of Con+ (n=1–18) with N2 are measured as a function of kinetic energy over a range of 0–15eV in a guided ion beam tandem mass spectrometer. A variety of Com+, ComN+, and ComN2+ (m⩽n) product ions are observed, all in endothermic processes, with collision-induced dissociation dominating the products for all clusters. Bond dissociation energies for both cobalt cluster nitrides and dinitrides are derived from threshold analysis of the energy dependence of the endothermic reactions using several different approaches. These values show only a mild dependence on cluster size over the range studied, although the Co13+–N bond energy is relatively weak. The bond energies of Con+–N for larger clusters suggest that a reasonable value for the desorption energy of atomic nitrogen from bulk phase cobalt is 6.3±0.2eV, which is somewhat lower than the only available value in the literature, an estimate based on the enthalpy of formation of bulk cobalt nitride. The trends in the cobalt nitride thermochemistry are also compared to previously determined metal-metal bond energies, D0(Con+–Co), and to D0(Fen+–N). Implications for catalytic ammonia production using cobalt versus iron are discussed.
Lower hybrid instability in a tokamak under neutral beam injection and magnetic shear
Authors: Kuley Animesh , Tripathi V. K.
Published: May 2008

A slab model is developed to study the excitation of lower hybrid instability triggered by the injection of a transverse neutral beam in a tokamak with magnetic shear. The lower hybrid mode is evanescent in the inner and outer region while propagating waves in the intermediate region. The neutral beam, on getting fully ionized in the plasma, resonantly couples with the lower hybrid wave in the intermediate region, driving the mode unstable. The theory of this process reveals that the growth rate scales as one third power of beam density, and increases significantly with the sheared magnetic field due to modification in the parallel wave number and the mode structure.
The effect of modulating a parameter in the logistic map
Authors: Elhadj Zeraoulia , Sprott J. C.
Published: May 2008

The effect of using the output of one logistic map to modulate the accessible parameter of a second logistic map is examined. Rigorous analytical results provide some predictions on the effect of this type of modulation, and those effects are tested numerically.
The accuracy of rotational constants predicted by high-level quantum-chemical calculations. I. molecules containing first-row atoms
Authors: Puzzarini Cristina , Heckert Miriam , Gauss Jürgen
Published: May 2008

A statistical analysis of the accuracy of theoretically predicted rotational constants is presented based on the data for a total of 16molecules and 97 isotopologues. Special focus is given on the treatment of electron correlation by using coupled-cluster methods up to quadruple excitations, core correlation, basis-set effects, zero-point vibrational corrections, and the electronic contribution to the rotational constants. The high accuracy achieved in the present investigation is demonstrated by the fact that at our best theoretical level, termed as CCSD(T)∕cc-pV∞Z+Δcore+ΔT+ΔQ+ΔBvib+ΔBel, the mean absolute error is 0.04% and the standard deviation is 0.07% in comparison with the available experimental data. The importance of higher excitations, core correlation, and zero-point vibrational effects is emphasized, while the electronic contribution is found to be less important.
Insights into the characterization of polymer-based organic thin-film transistors using capacitance-voltage analysis
Authors: Hamadani B. H. , Richter C. A. , Suehle J. S. , Gundlach D. J.
Published: May 2008

Frequency dependent capacitance-voltage characteristics of organic thin-film transistors based on poly(3-hexylthiophene) as the active polymer layer are investigated. The frequency response of the channel capacitance in accumulation is examined through an analytical transmission line model, with the effect of contact resistances included in the model to account for deviations from ideal behavior. The model provides an excellent fit to the data. Furthermore, we show that the technique can be used to extract device parameters such as the mobility and the contact resistance and quantitative information on the influence of charge trapping on transport.
A compact, multiangle electron spectrometer for ultraintense laser-plasma interaction experiments
Authors: Gotchev O. V. , Brijesh P. , Nilson P. M. , Stoeckl C. , Meyerhofer D. D.
Published: May 2008

Experiments on the multiterawatt (MTW) laser at the Laboratory for Laser Energetics will study the effect of the focal-spot shape on the forward acceleration and collimation of electrons. A compact electron spectrometer has been developed to record the energy spectra of electrons ejected in the interaction of the laser at multiple angular locations simultaneously. The modular system with replaceable magnets provides an adjustable energy band, currently 0.2–6MeV. The detector is an array of imaging plates. The device is designed to operate in the high-noise environment (bremsstrahlung and Compton x rays, gamma rays, and scattered electrons), while being compact enough to fit in the 30cm radius MTW target chamber. The detector geometry and shielding were optimized with the particle/radiation transport code GEANT4. Calibration was performed with beta sources. The required dynamic range, sensitivity, and resolution were confirmed with initial MTW experimental data.
Proton-beam driven fast ignition of inertially confined fuels: Reduction of the ignition energy by the use of two proton beams with radially shaped profiles
Authors: Temporal M. , Honrubia J. J. , Atzeni S.
Published: May 2008

Fast ignition of a spherical compressed deuterium-tritium assembly induced by the energy deposition of laser-accelerated proton beams is considered. An efficient way to reduce the ignition energy consists of using a two proton beams scheme [M. Temporal, Phys Plasmas 13, 122704 (2006)]. For a uniformly compressed fuel at 500g∕cm3 irradiated by proton beams with Maxwellian energy distribution with a temperature of 4MeV, the ignition energy is 10kJ using only one proton beam and reduces to a total of 8kJ with the two-beam scheme. Further reduction of the ignition energy is found by using a first beam with annular radial profile and a second beam with the uniform radial profile. It is found that the first beam causes some additional fuel compression and confinement that decrease the total beam energy required for the ignition to 6kJ, which is 40% smaller than in the case of a single beam with uniform radial profile.
Using a nondirect product discrete variable representation for angular coordinates to compute vibrational levels of polyatomic molecules
Authors: Wang Xiao-Gang , Carrington Tucker
Published: May 2008

In this paper we test a nondirect product discrete variable representation (DVR) method for solving the bend vibration problem and compare it with well-established direct product DVR and finite basis representation approaches.
Monte Carlo simulations of liquid crystals between microstructured substrates
Authors: Cheung David L.
Published: May 2008

The structure of a model liquid crystalline fluid confined between two microstructured substrates is studied through Monte Carlo simulations. A simple model for a structured substrate, similar in spirit to those used for rough walls of walls with grafted polymers, is introduced. It is found that varying the structure of the substrate, a transition in the alignment of the confined fluid, from parallel to perpendicular, is induced. For particular substrate structures, it is possible to induce tilted alignment in the confined fluid, the tilt angle being temperature dependent.
Structural, energetic, and electronic properties of hydrogenated titanium clusters
Authors: Dhilip Kumar T. J. , Tarakeshwar P. , Balakrishnan N.
Published: May 2008

Hydrogen undergoes dissociative chemisorption on small titanium clusters. How the electronic structure of the cluster changes as a function of the number of adsorbed hydrogen atoms is an important issue in nanocatalysis and hydrogen storage. In this paper, a detailed theoretical investigation of the structural, energetic, and electronic properties of the icosahedral Ti13 cluster is presented as a function of the number of adsorbed hydrogen atoms. The results show that hydrogen loaded Ti13H20 and Ti13H30 clusters are exceptionally stable and are characterized by hydrogen multicenter bonds. In Ti13H20, the dissociated hydrogen atoms are bound to each of the 20 triangular faces of Ti13, while in Ti13H30, they are bound to the 30 Ti–Ti edges of Ti13. Consequently, the chemisorption and desorption energies of the Ti13H20 (1.93eV, 3.10eV) are higher than that of Ti13H30 (1.13eV, 1.95eV). While increased hydrogen adsorption leads to an elongation of the Ti–Ti bonds, there is a concomitant increase in the electrostatic interaction between the dissociated hydrogen atoms and the Ti13 cluster. This enhanced interaction results from the participation of the subsurface titanium atom at higher hydrogen concentrations. Illustrative results of hydrogen saturation on the larger icosahedral Ti55 cluster are also discussed. The importance of these results on hydrogen saturated titanium clusters in elucidating the mechanism of hydrogen adsorption and desorption in titanium doped complex metal hydrides is discussed.
Thermodynamic trends in the uptake capacity of porous adsorbents on methane and hydrogen
Authors: Chakraborty Anutosh , Saha Bidyut Baran , Koyama Shigeru , Ng Kim Choon , Yoon Seong-Ho
Published: May 2008

A considerable progress has been made for the development of novel porous materials with controlled architectures and surface treatment. An important feature of these adsorbent materials is the maximization of adsorption capacity at Henry’s region. A thermodynamic framework is presented to capture the relationship between the pore specific surface areas with the enthalpy of adsorption. By using this approach, the scientific community can be guided to the development of advanced porous adsorbent and adsorbate pairs. The adsorbents with the highest porous surface areas tend to possess lower isosteric heat of adsorption when storing the methane and hydrogen gases at room temperature.