bluuebunny/crossref_metadata_2025 huggingface dataset:
A combined water balance and tree ring approach to understanding the potential hydrologic effects of climate change in the central Rocky Mountain region
Authors: Gray Stephen T. , McCabe Gregory J.
Published: May 2010

Models suggest that average temperatures in the central Rocky Mountains will increase by >3°C over the next century, while precipitation may remain within late Holocene boundaries. This study investigates the potential hydrologic effects of such warming when combined with the full range of precipitation variability experienced over the past millennium. Using the upper Yellowstone drainage as a test case, a water balance model is constructed to estimate river discharge from precipitation and temperature inputs (r = 0.85 versus observed). The model then was run using tree ring precipitation estimates for 1177–1910 and 1911–1995 A.D. combined with (1) average observed temperatures 1896–1995; (2) reconstructed Northern Hemisphere temperatures since 1177; or (3) Intergovernmental Panel on Climate Change temperature projections for 2025, 2050, and 2100. Discharge estimates generated by driving the model with tree ring precipitation for 1911–1995 and observed temperatures served as a baseline for comparisons with other climate runoff scenarios. All combinations of the various temperature scenarios and pre‐1911 precipitation resulted in mean discharge below the gauge period baseline. Projected temperatures for 2050 and 2100 produced the lowest mean discharge at 85% and 76% of baseline, respectively. Combining observed temperatures with the paleoprecipitation scenarios created numerous multidecadal periods with discharge <85% of baseline. Discharge during these same multidecadal droughts declined an additional 16–34% under the 2025–2100 temperature regimes. Likewise inherent multidecadal precipitation variability adds a large degree of nonstationarity to the climate change responses seen in discharge estimates. While this combined tree ring and water balance scenario exercise does not provide precise forecasts for future conditions, these results suggest that a 1°–3°C warming could have major negative effects on water availability in the upper Yellowstone. These results also indicate that twentieth‐century observations paint an incomplete and potentially overly optimistic picture of regional water supplies.
Unprecedented coastal upwelling in the East/Japan Sea and linkage to long‐term large‐scale variations
Authors: Park Kyung‐Ae , Kim Kyung‐Ryul
Published: May 2010

Unprecedented cold water was observed off the east coast of Korea in the summer of 2007, with the lowest temperature since 1961. The 9–year QuikSCAT satellite scatterometer wind field showed that the spectacular coastal upwelling was induced by Ekman transport to the offshore area by strong southerly winds. These characteristic winds were produced by the large scale air pressure distribution of typhoon Pabuk to the west, which stayed longest for the past half century, along with the North Pacific High (NPH) in the east. The duration of both tropical depressions and the westward moving NPH have shown characteristic increasing trends over several decades, which facilitate favorable conditions for the surface cooling. The negative trend in coastal water temperatures, in contrast with a positive trend offshore by global warming, supports the conclusion that small scale sea surface temperature variations at the coastal area could be remotely affected by long–term large–scale variations.
Effects of dead time losses on terrestrial gamma ray flash measurements with the Burst and Transient Source Experiment
Authors: Gjesteland T. , Østgaard N. , Connell P. H. , Stadsnes J. , Fishman G. J.
Published: May 2010

Measurements from the Burst and Transient Source Experiment (BATSE) instrument on the Compton Gamma Ray Observatory (CGRO) are the only ones where characteristics of single terrestrial gamma ray flashes (TGFs) have been obtained thus far. However, it has been reported that the measurements suffer from significant dead time losses which complicates the analysis and raises question about earlier BATSE studies. These losses are due to the high‐intensity flux combined with limitations of the time resolution of the instrument. Since these losses will affect both the spectrum and the temporal distribution of the individual TGFs, results based on BATSE data need to be revisited, including our own. We have therefore developed a Monte Carlo method to study the effects of these dead time losses. We show that the energy spectrum of TGFs becomes softer as the dead time losses increase. We also show that the time delay between the light curves of hard (E > 300 keV) and soft (E < 300 keV) photons increases significantly as the dead time losses increase. The Monte Carlo approach also enables us to identify the BATSE TGFs where the dead time effects can be corrected. These are the short‐duration single‐peaked TGFs. Without correcting for dead time losses we find that these short single‐peak TGFs have a softer energy spectrum and larger time delay than the multipeaked TGFs. After correcting for dead time losses we perform a new analysis of production altitudes and find that the production altitude is reduced compared to analysis without dead time losses. The new production altitudes combined with dead time losses are also consistent with the apparent large time delays. Our method gives consistent results regarding production altitude and time delays and indicates that the corrected TGF intensities measured by BATSE are 3 to 4 times brighter than the uncorrected measurements would indicate. We also show that the production mechanism of these TGFs has a typical duration of 250 μs.
Origin of deep ocean microseisms by using teleseismic body waves
Authors: Landès Matthieu , Hubans Fabien , Shapiro Nikolai M. , Paul Anne , Campillo Michel
Published: May 2010

Recent studies of oceanic microseisms have concentrated on fundamental mode surface waves. Extraction of fundamental mode Rayleigh and Love wave Green functions from station‐station correlations of ambient seismic noise has recently been demonstrated to be a very powerful tool for imaging of the Earth's crust and uppermost mantle. In this study we concentrate on energetic arrivals in two frequency bands around the primary (14 s) and the secondary (7 s) microseismic peaks that appear at near‐zero times in noise cross correlations. Thanks to a polarization analysis of data from the Eastern Turkey Seismic Experiment network, we identify this “near‐zero time” signal as an upcoming P wave in the secondary microseismic frequency band (5–10 s). In a second step, analyzing noise cross correlations from three different arrays (in Yellowstone, in Turkey, and in Kyrgyzstan), we determine the origin of these signals by means of beam‐forming analysis and its projection on the Earth. Our results show that in the 0.1–0.3 Hz frequency band, the energetic “near‐zero” time arrivals in seismic noise cross correlations are mainly formed by teleseismic P, PP, and PKP waves. Generation of this ambient body waves in the secondary microseismic band presents a marked seasonal behavior with sources located in southern and northern oceans during summer and winter, respectively. Moreover, body wave array analysis is accurate enough to confirm that significant amount of the microseism energy is generated far from the coast in deep oceans.
Nordic seas transit time distributions and anthropogenic CO2
Authors: Olsen Are , Omar Abdirahman M. , Jeansson Emil , Anderson Leif G. , Bellerby Richard G. J.
Published: May 2010

The distribution and inventory of anthropogenic carbon (DICant) in the Nordic seas are determined using the transit time distribution (TTD) approach. To constrain the shape of the TTDs in the Nordic seas, CO2 is introduced as an age tracer and used in combination with water age estimates determined from CFC‐12 data. CO2 and CFC‐12 tracer ages constitute a very powerful pair for constraining the shape of TTDs. The highest concentrations of DICant appear in the warm and well‐ventilated Atlantic water that flows into the region from the south, and concentrations are typically lower moving west into the colder Arctic surface waters. The depth distribution of DICant reflects the extent of ventilation in the different areas. The Nordic seas DICant inventory for 2002 was constrained to between 0.9 and 1.4 Gt DICant, corresponding to ∼1% of the global ocean DICant inventory. The TTD‐derived DICant estimates were compared with estimates derived using four other approaches, revealing significant differences with respect to the TTD‐derived estimates, which can be related to issues with some of the underlying assumptions of these other approaches. Specifically, the Tracer combining Oxygen, inorganic Carbon and total Alkalinity (TrOCA) method appears to underestimate DICant in the Nordic seas, the ΔC* shortcut and the approach of Jutterström et al. (2008) appear to overestimate DICant at most depths in this area, and finally the approach of Tanhua et al. (2007) appears to underestimate Nordic seas DICant below 3000 m and overestimate it above 1000 m.
Phase asymmetric downstream development of the North Atlantic Oscillation and its impact on the East Asian winter monsoon
Authors: Sung Mi‐Kyung , Lim Gyu‐Ho , Kug Jong‐Seong
Published: May 2010

The phase asymmetry in a downstream pattern of the North Atlantic Oscillation (NAO) is examined during boreal winter time. We compared the downstream anomaly patterns associated with the positive and negative persistent NAO events over several days. Both phases of the persistent NAO events accompany quasi‐stationary wave trains in downstream upper levels. However, a distinct low level anomaly appears only for the negative persistent NAO events. The low level anomaly migrates eastward as a surface anticyclone that is confined to the low troposphere. A few days later, the surface anticyclone reaches central Siberia and induces cold advection over East Asia. Therefore, the phase‐dependent downstream development of the NAO expands the impact of the NAO to the East Asian region. We also discuss the possible interaction between the upper and lower level anomalies, a necessary condition for the amplification of the Siberian high.
Subtle biological responses to increased CO2 concentrations by Phaeocystis globosa Scherffel, a harmful algal bloom species
Authors: Wang Yan , Smith Walker O. , Wang Xiaodong , Li Shaoshan
Published: May 2010

Recent investigations into the role of carbon dioxide on phytoplankton growth and composition have clearly shown differential effects among species and assemblages, suggesting that increases in oceanic CO2 may play a critical role in structuring lower trophic levels of marine systems in the future. Furthermore, alarming increases in the occurrence of harmful algal blooms (HABs) in coastal waters have been observed, and while not uniform among systems, appear in some manner to be linked to human impacts (eutrophication) on coastal systems. Models of HABs are in their infancy and do not at present include sophisticated biological effects or their environmental controls. Here we show that subtle biological responses occur in the HAB species Phaeocystis globosa Scherffel as a result of CO2 enrichment induced by gentle bubbling. The alga, which has a polymorphic life history involving the formation of both colonies and solitary cells, exhibited altered growth rates of colonial and solitary forms at [CO2] of 750 ppm, as well as increased colony formation. In addition, substantial modifications of elemental and photosynthetic constituents of the cells (C cell−1, N cell−1, potential quantum yield, chl a cell−1) occurred under elevated CO2 concentrations compared to those found at present CO2 levels. In contrast, other individual and population variables (e.g., colony diameter, total chlorophyll concentration, carbon/nitrogen ratio) were unaffected by increased CO2. Our results suggest that predictions of the future impacts of Phaeocystis blooms on coastal ecosystems and local biogeochemistry need to carefully examine the subtle biological responses of this alga in addition to community and ecosystem effects.
Viruses and Langerhans cells
Authors: Cunningham Anthony L , Abendroth Allison , Jones Cheryl , Nasr Najla , Turville Stuart
Published: May 2010

Langerhans cells (LCs) are the resident dendritic cells (DCs) of epidermis in human mucosal stratified squamous epithelium and the skin. A phenotypically similar DC has recently been discovered as a minor population in the murine dermis. In epidermis, LCs function as sentinel antigen‐presenting cells that can capture invading viruses such as herpes simplex virus (HSV), varicella‐zoster virus (VZV) and human immunodeficiency virus (HIV). This interaction between LCs and viruses results in highly variable responses, depending on the virus as discussed in this review. For example, HSV induces apoptosis in LCs but HIV does not. LCs seem to be the first in a complex chain of antigen presentation to T cells in lymph nodes for HSV and possibly VZV, or they transport virus to T cells, as described for HIV and maybe VZV. Together with epidermal keratinocytes they may also have a role in the initial innate immune response at the site of infection in the epidermis, although this is not fully known. The full spectrum of biological responses of LCs even to these viruses has yet to be understood and will require complementary studies in human LCs in vitro and in murine models in vivo.
The Flavanol (−)-Epicatechin Prevents Stroke Damage through the Nrf2/HO1 Pathway
Authors: Shah Zahoor A , Li Rung-Chi , Ahmad Abdullah S , Kensler Thomas W , Yamamoto Masayuki , Biswal Shyam , Doré Sylvain
Published: May 2010

Epidemiologic studies have shown that foods rich in polyphenols, such as flavanols, can lower the risk of ischemic heart disease; however, the mechanism of protection has not been clearly established. In this study, we investigated whether epicatechin (EC), a flavanol in cocoa and tea, is protective against brain ischemic damage in mice. Wild-type mice pretreated orally with 5, 15, or 30 mg/kg EC before middle cerebral artery occlusion (MCAO) had significantly smaller brain infarcts and decreased neurologic deficit scores (NDS) than did the vehicle-treated group. Mice that were posttreated with 30 mg/kg of EC at 3.5 hours after MCAO also had significantly smaller brain infarcts and decreased NDS. Similarly, WT mice pretreated with 30 mg/kg of EC and subjected to N-methyl-D-aspartate (NMDA)-induced excitotoxicity had significantly smaller lesion volumes. Cell viability assays with neuronal cultures further confirmed that EC could protect neurons against oxidative insults. Interestingly, the EC-associated neuroprotection was mostly abolished in mice lacking the enzyme heme oxygenase 1 (HO1) or the transcriptional factor Nrf2, and in neurons derived from these knockout mice. These results suggest that EC exerts part of its beneficial effect through activation of Nrf2 and an increase in the neuroprotective HO1 enzyme.
Brown Adipose Tissue, Whole‐Body Energy Expenditure, and Thermogenesis in Healthy Adult Men
Authors: Yoneshiro Takeshi , Aita Sayuri , Matsushita Mami , Kameya Toshimitsu , Nakada Kunihiro , Kawai Yuko , Saito Masayuki
Published: May 2010

Brown adipose tissue (BAT) can be identified by 18F‐fluorodeoxyglucose (FDG)‐positron emission tomography (PET) in adult humans. Thirteen healthy male volunteers aged 20–28 years underwent FDG‐PET after 2‐h cold exposure at 19 °C with light‐clothing and intermittently putting their legs on an ice block. When exposed to cold, 6 out of the 13 subjects showed marked FDG uptake into adipose tissue of the supraclavicular and paraspinal regions (BAT‐positive group), whereas the remaining seven showed no detectable uptake (BAT‐negative group). The BMI and body fat content were similar in the two groups. Under warm conditions at 27 °C, the energy expenditure of the BAT‐positive group estimated by indirect calorimetry was 1,446 ± 97 kcal/day, being comparable with that of the BAT‐negative group (1,434 ± 246 kcal/day). After cold exposure, the energy expenditure increased markedly by 410 ± 293 (P < 0.05) and slightly by 42 ± 114 kcal/day (P = 0.37) in the BAT‐positive and ‐negative groups, respectively. A positive correlation (P < 0.05) was found between the cold‐induced rise in energy expenditure and the BAT activity quantified from FDG uptake. After cold exposure, the skin temperature in the supraclavicular region close to BAT deposits dropped by 0.14 °C in the BAT‐positive group, whereas it dropped more markedly (P < 0.01) by 0.60 °C in the BAT‐negative group. The skin temperature drop in other regions apart from BAT deposits was similar in the two groups. These results suggest that BAT is involved in cold‐induced increases in whole‐body energy expenditure, and, thereby, the control of body temperature and adiposity in adult humans.
Ethnic‐Specific Differences in Abdominal Subcutaneous Adipose Tissue Compartments
Authors: Kohli Simi , Sniderman Allan D. , Tchernof André , Lear Scott A.
Published: May 2010

South Asians have a higher prevalence of cardiovascular disease (CVD) than Europeans. Studies have identified distinct subcompartments of subcutaneous adipose tissue (SAT) that provide insight into the relationship between abdominal obesity and metabolic risk factors in different ethnic groups. Our objective was to determine the relationship between SAT compartments and fat‐free mass (FFM) between South Asian and European cohorts, and between men and women. Healthy Europeans and South Asians (n = 408) were assessed for FFM via dual energy X‐ray absorptiometry, and SAT areas by computed tomography (CT). SAT was subdivided into superficial subcutaneous abdominal adipose tissue (SSAT) and deep subcutaneous abdominal adipose tissue (DSAT). Linear regression analyses were performed using DSAT and SSAT as separate dependent variables and FFM and ethnicity as primary independent variables adjusting for age, gender, income, education, and smoking status. Results showed that South Asian men had significantly higher amounts of DSAT (median 187.65 cm2 vs. 145.15 cm2, P < 0.001), SSAT (median 92.0 cm2 vs. 76.1 cm2, P = 0.046), and body fat mass (BFM) (25.1 kg vs. 22.6 kg, P = 0.049) than European men. In a fully adjusted model, South Asians showed significantly greater DSAT at any FFM than Europeans. Women had more SSAT at any given FFM than men and less DSAT at any given FFM than men, irrespective of ethnic background. In conclusion, South Asians had more DSAT than Europeans and men had relatively more DSAT than women. These data suggest that specific fat depots are influenced by ethnicity and gender; therefore, could provide insight into the relationship between ethnicity, gender and subsequent risk for CVD.
ATP storage and uptake by isolated pancreatic zymogen granules
Authors: Haanes Kristian A. , Novak Ivana
Published: May 2010

ATP is released from pancreatic acini in response to cholinergic and hormonal stimulation. The same stimuli cause exocytosis of ZG (zymogen granules) and release of digestive enzymes. The aim of the present study was to determine whether ZG stored ATP and to characterize the uptake mechanism for ATP transport into the ZG. ZG were isolated and the ATP content was measured using luciferin/luciferase assays and was related to protein in the sample. The estimate of ATP concentration in freshly isolated granules was 40–120 μM. The ATP uptake had an apparent Km value of 4.9±2.1 mM when granules were incubated without Mg2+ and a Km value of 0.47±0.05 mM in the presence of Mg2+, both in pH 6.0 buffers. The uptake of ATP was significantly higher at pH 7.2 compared with pH 6.0 solutions. The anion transport blockers DIDS (4,4′-di-isothiocyanostilbene-2,2′-disulfonate) and Evans Blue inhibited ATP transport. Western blot analysis on the ZG showed the presence of VNUT (vesicular nucleotide transporter). Together, these findings indicate that VNUT may be responsible for the ATP uptake into ZG. Furthermore, the present study shows the presence of ATP together with digestive enzymes in ZG. This indicates that co-released ATP would regulate P2 receptors in pancreatic ducts and, thus, ductal secretion, and this would aid delivery of enzymes to the duodenum.
The dissociated form of κ-casein is the precursor to its amyloid fibril formation
Authors: Ecroyd Heath , Thorn David C. , Liu Yanqin , Carver John A.
Published: May 2010

Bovine milk κ-casein forms a self-associating oligomeric micelle-like species, in equilibrium with dissociated forms. In its native form, intra- and inter-molecular disulfide bonds lead to the formation of multimeric species ranging from monomers to decamers. When incubated under conditions of physiological pH and temperature, both reduced and non-reduced κ-casein form highly structured β-sheet amyloid fibrils. We investigated whether the precursor to κ-casein fibril formation is a dissociated state of the protein or its oligomeric micelle-like form. We show that reduced κ-casein is capable of forming fibrils well below its critical micelle concentration, i.e. at concentrations where only dissociated forms of the protein are present. Moreover, by regulating the degree of disulfide linkages, we were able to investigate how oligomerization of κ-casein influences its propensity for fibril formation under conditions of physiological pH and temperature. Thus, using fractions containing different proportions of multimeric species, we demonstrate that the propensity of the disulfide-linked multimers to form fibrils is inversely related to their size, with monomeric κ-casein being the most aggregation prone. We conclude that dissociated forms of κ-casein are the amyloidogenic precursors to fibril formation rather than oligomeric micelle-like species. The results highlight the role of oligomerization and natural binding partners in preventing amyloid fibril formation by disease-related proteins in vivo.
Role of phosphoinositide 3-kinase β in platelet aggregation and thromboxane A2 generation mediated by Gi signalling pathways
Authors: Garcia Analia , Kim Soochong , Bhavaraju Kamala , Schoenwaelder Simone M. , Kunapuli Satya P.
Published: May 2010

PI3Ks (phosphoinositide 3-kinases) play a critical role in platelet functional responses. PI3Ks are activated upon P2Y12 receptor stimulation and generate pro-aggregatory signals. P2Y12 receptor has been shown to play a key role in the platelet aggregation and thromboxane A2 generation caused by co-stimulation with Gq or Gz, or super-stimulation of Gi pathways. In the present study, we evaluated the role of specific PI3K isoforms α, β, γ and δ in platelet aggregation, thromboxane A2 generation and ERK (extracellular-signal-regulated kinase) activation. Our results show that loss of the PI3K signal impaired the ability of ADP to induce platelet aggregation, ERK phosphorylation and thromboxane A2 generation. We also show that Gq plus Gi- or Gi plus Gz-mediated platelet aggregation, ERK phosphorylation and thromboxane A2 generation in human platelets was inhibited by TGX-221, a PI3Kβ-selective inhibitor, but not by PIK75 (a PI3Kα inhibitor), AS252424 (a PI3Kγ inhibitor) or IC87114 (a PI3Kδ inhibitor). TGX-221 also showed a similar inhibitory effect on the Gi plus Gz-mediated platelet responses in platelets from P2Y1−/− mice. Finally, 2MeSADP (2-methyl-thio-ADP)-induced Akt phosphorylation was significantly inhibited in the presence of TGX-221, suggesting a critical role for PI3Kβ in Gi-mediated signalling. Taken together, our results demonstrate that PI3Kβ plays an important role in ADP-induced platelet aggregation. Moreover, PI3Kβ mediates ADP-induced thromboxane A2 generation by regulating ERK phosphorylation.
Lattice Boltzmann methods for thermal flows: Continuum limit and applications to compressible Rayleigh–Taylor systems
Authors: Scagliarini A. , Biferale L. , Sbragaglia M. , Sugiyama K. , Toschi F.
Published: May 2010

We compute the continuum thermohydrodynamical limit of a new formulation of lattice kinetic equations for thermal compressible flows, recently proposed by Sbragaglia et al. [J. Fluid Mech. 628, 299 (2009)]. We show that the hydrodynamical manifold is given by the correct compressible Fourier–Navier–Stokes equations for a perfect fluid. We validate the numerical algorithm by means of exact results for transition to convection in Rayleigh–Bénard compressible systems and against direct comparison with finite-difference schemes. The method is stable and reliable up to temperature jumps between top and bottom walls of the order of 50% the averaged bulk temperature. We use this method to study Rayleigh–Taylor instability for compressible stratified flows and we determine the growth of the mixing layer at changing Atwood numbers up to At∼0.4. We highlight the role played by the adiabatic gradient in stopping the mixing layer growth in the presence of high stratification and we quantify the asymmetric growth rate for spikes and bubbles for two dimensional Rayleigh–Taylor systems with resolution up to Lx×Lz=1664×4400 and with Rayleigh numbers up to Ra∼2×1010.
On KSGNS representations on Krein C∗-modules
Authors: Heo Jaeseong , Hong Jang Pyo , Ji Un Cig
Published: May 2010

Motivated by the notion of P-functional, we introduce a notion of α-completely positive map between  ∗-algebras which is a Hermitian map satisfying a certain positivity condition, and then a α-completely positive map which is not completely positive is constructed. We establish the Kasparov-Stinespring-Gelfand-Naimark-Segal constructions of C∗-algebra and  ∗-algebra on Krein C∗-modules with α-completely positive maps.
A comparative analysis of Painlevé, Lax pair, and similarity transformation methods in obtaining the integrability conditions of nonlinear Schrödinger equations
Authors: Al Khawaja U.
Published: May 2010

We derive the integrability conditions of nonautonomous nonlinear Schrödinger equations using the Lax pair and similarity transformation methods. We present a comparative analysis of these integrability conditions with those of the Painlevé method. We show that while the Painlevé integrability conditions restrict the dispersion, nonlinearity, and dissipation/gain coefficients to be space independent and the external potential to be only a quadratic function of position, the Lax Pair and the similarity transformation methods allow for space-dependent coefficients and an external potential that is not restricted to the quadratic form. The integrability conditions of the Painlevé method are retrieved as a special case of our general integrability conditions. We also derive the integrability conditions of nonautonomous nonlinear Schrödinger equations for two- and three-spacial dimensions.
Multiscale investigation of chemical interference in proteins
Authors: Samiotakis Antonios , Homouz Dirar , Cheung Margaret S.
Published: May 2010

We developed a multiscale approach (MultiSCAAL) that integrates the potential of mean force obtained from all-atomistic molecular dynamics simulations with a knowledge-based energy function for coarse-grained molecular simulations in better exploring the energy landscape of a small protein under chemical interference such as chemical denaturation. An excessive amount of water molecules in all-atomistic molecular dynamics simulations often negatively impacts the sampling efficiency of some advanced sampling techniques such as the replica exchange method and it makes the investigation of chemical interferences on protein dynamics difficult. Thus, there is a need to develop an effective strategy that focuses on sampling structural changes in protein conformations rather than solvent molecule fluctuations. In this work, we address this issue by devising a multiscale simulation scheme (MultiSCAAL) that bridges the gap between all-atomistic molecular dynamics simulation and coarse-grained molecular simulation. The two key features of this scheme are the Boltzmann inversion and a protein atomistic reconstruction method we previously developed (SCAAL). Using MultiSCAAL, we were able to enhance the sampling efficiency of proteins solvated by explicit water molecules. Our method has been tested on the folding energy landscape of a small protein Trp-cage with explicit solvent under 8M urea using both the all-atomistic replica exchange molecular dynamics and MultiSCAAL. We compared computational analyses on ensemble conformations of Trp-cage with its available experimental NOE distances. The analysis demonstrated that conformations explored by MultiSCAAL better agree with the ones probed in the experiments because it can effectively capture the changes in side-chain orientations that can flip out of the hydrophobic pocket in the presence of urea and water molecules. In this regard, MultiSCAAL is a promising and effective sampling scheme for investigating chemical interference which presents a great challenge when modeling protein interactions in vivo.
High electric field effects on gigahertz dielectric properties of water measured with microwave microfluidic devices
Authors: Song Chunrong , Wang Pingshan
Published: May 2010

Silicon microstrip line devices with 260 nm planar microfluidic channels are fabricated and used to investigate water dielectric saturation effects. Microwave scattering parameter measurements are conducted from 1 to 16 GHz under different uniform dc electric fields. When the applied dc field is increased to ∼1 MV/cm, the measured transmission coefficient S21 is increased up to 18 dB, which indicates a large change in water dielectric properties. Extracted water permittivity (ε=ε′+jε″) shows that ε′ and ε″ are changed up to 70% and 50%, respectively.
The decomposition of metric n-Lie algebras and the uniqueness
Authors: Chen Zhiqi , Liang Ke
Published: May 2010

In this paper, we show that the orthogonal decomposition of any metric n-Lie algebra into indecomposable nondegenerate ideals is unique up to an isometry. Moreover, the decomposition is unique up to the order of the ideals if the center of the n-Lie algebra is zero.
Turbulent drag reduction in nonionic surfactant solutions
Authors: Tamano Shinji , Itoh Motoyuki , Kato Katsuo , Yokota Kazuhiko
Published: May 2010

There are only a few studies on the drag-reducing effect of nonionic surfactant solutions which are nontoxic and biodegradable, while many investigations of cationic surfactant solutions have been performed so far. First, the drag-reducing effects of a nonionic surfactant (AROMOX), which mainly consisted of oleyldimethylamineoxide, was investigated by measuring the pressure drop in the pipe flow at solvent Reynolds numbers Re between 1000 and 60 000. Second, we investigated the drag-reducing effect of a nonionic surfactant on the turbulent boundary layer at momentum-thickness Reynolds numbers Reθ from 443 to 814 using two-component laser-Doppler velocimetry and particle image velocimetry systems. At the temperature of nonionic surfactant solutions, T=25 °C, the maximum drag reduction ratio for AROMOX 500 ppm was about 50%, in the boundary layer flow, although the drag reduction ratio was larger than 60% in pipe flow. Turbulence statistics and structures for AROMOX 500 ppm showed the behavior of typical drag-reducing flow such as suppression of turbulence and modification of near-wall vortices, but they were different from those of drag-reducing cationic surfactant solutions, in which bilayered structures of the fluctuating velocity vectors were observed in high activity.
Flow past a circular cylinder at low Reynolds number: Oblique vortex shedding
Authors: Behara Suresh , Mittal Sanjay
Published: May 2010

Oblique shedding in the laminar regime for the flow past a nominally two-dimensional circular cylinder has been investigated numerically via a stabilized finite element method. No-slip condition on one of the sidewalls leads to the formation of a boundary layer which promotes oblique vortex shedding. Computations are carried out for three values of Reynolds number (Re): 60, 100, and 150. Cellular shedding is observed in all cases. Three cells are observed along the span for the Re=60 flow while only two cells are formed at Re=100 and 150. Spotlike vortex dislocations form at the junction of the cells. The frequency of the appearance of the dislocations increases with Re. Cellular shedding leads to low frequency modulation in the time histories of aerodynamic coefficients. Lowest value of drag is achieved at a time instant corresponding to the appearance of a new dislocation in the near wake. The vortex shedding frequency as well as the oblique angle of the primary vortices is found to vary with time for the Re=60 flow. Their variation is also related to the appearance of dislocations in the near wake. It is found that the vortex shedding frequency (Stθ) is related to the frequency observed for parallel shedding (St0) and the angle of the oblique vortices (θ) by the relation: Stθ=St0 cos θ. This relationship was proposed earlier for the case when the vortex shedding frequency and the oblique angle do not change with time. The velocity fluctuations are found to decrease with increase in θ. For the Re=100 and 150 flow, the oblique angle of the vortices and the shedding frequency outside the end cell do not change with time. However, θ and Stθ depend on the aspect ratio of the cylinder. The oblique shedding angle, for various lengths of endplate and Re, is found to vary linearly with the thickness of the boundary layer on the side wall.
On the relationship between the wall-shear-stress and transient-growth disturbances in a laminar boundary layer
Authors: Naguib A. M. , Morrison J. F. , Zaki T. A.
Published: May 2010

The present study is motivated by the development of wall-based flow-state estimators for feedback control of transient-growth disturbances in a laminar boundary layer. Such estimators have been successfully demonstrated in recent numerical studies, but they rely on information that, while available in simulations, is generally not accessible in the laboratory. Here, some physical aspects of transient-growth modes and their relationship to the unsteady wall shear stress are examined to guide the development of estimation methods that perform satisfactorily yet are practical to implement. The usefulness of the resulting physical understanding for flow estimation is demonstrated using a proper orthogonal decomposition mode estimator, applied to a direct numerical simulation of boundary layer transition beneath free-stream turbulence. The results shed light on the strengths and weaknesses of employing each of the streamwise and spanwise wall-shear-stress components in estimating the disturbance wall-normal velocity and vorticity fields. It is also found that the streamwise-elongated nature of transient-growth disturbances allows coarse sampling of the wall-shear-stress information used in the estimation without substantially deteriorating the estimation accuracy. This is particularly true for estimates based on the streamwise shear stress.
Sulfur gradient-driven Se diffusion at the CdS/CuIn(S,Se)2 solar cell interface
Authors: Weinhardt L. , Bär M. , Pookpanratana S. , Morkel M. , Niesen T. P. , Karg F. , Ramanathan K. , Contreras M. A. , Noufi R. , Umbach E. , Heske C.
Published: May 2010

The diffusion behavior of Se at the CdS/Cu(In,Ga)(S,Se)2 thin film solar cell interface was investigated by x-ray photoelectron spectroscopy and x-ray excited Auger electron spectroscopy. Buffer/absorber structures with S/Se ratios between zero and three at the initial Cu(In,Ga)(S,Se)2 surface were analyzed. Samples from a high-efficiency laboratory process (NREL) as well as from an industrial large-area process (AVANCIS) were investigated. We find selenium diffusion into the CdS buffer layer, the magnitude of which strongly depends on the S content at the absorber surface. The associated modification of the heterojunction partners has significant impact on the electronic structure at the interface.
A super resolution metalens with phase compensation mechanism
Authors: Ma Changbao , Liu Zhaowei
Published: May 2010

We propose a metalens consisting of a metamaterial slab that can support the propagation of waves with high wave vectors and a nonperiodic plasmonic waveguide coupler atop that can provide phase compensation and wave vector matching. The principle of the metalens is analyzed and numerically verified. We show that the metalens not only can achieve super resolution focusing but also has the fundamental properties of a conventional optical lens, such as Fourier transform and imaging. The proposed metalens may offer exceptional opportunities for optical system design and information processing.
Programmed packaging of multicomponent envelope-type nanoparticle system for gene delivery
Authors: Pozzi Daniela , Marianecci Carlotta , Carafa Maria , Marchini Cristina , Montani Maura , Amici Augusto , Caracciolo Giulio
Published: May 2010

A programmed packaging strategy to develop a multicomponent envelope-type nanoparticle system (MENS) is presented. To this end, we took specific advantage of using in-house tailored liposomes that have been recently shown to exhibit intrinsic endosomal rupture properties that allow plasmid DNA to escape from endosomes and to enter the nucleus with extremely high efficiency. Transfection efficiency experiments on NIH 3T3 mouse fibroblasts indicate that MENS is a promising transfection candidate.
Phase diagram of 3β-[N-(N,N-dimethylaminoethane)-carbamoyl]- cholesterol−dioleoylphosphatidylethanolamine/DNA complexes suggests strategies for efficient lipoplex transfection
Authors: Pozzi Daniela , Amenitsch Heinz , Marchini Cristina , Caracciolo Giulio
Published: May 2010

Synchrotron small angle x-ray scattering and electrophoresis on agarose gels have been applied to construct the phase diagram of the ternary complex made up of the cationic lipid 3β-[N-(N,N-dimethylaminoethane)-carbamoyl]-cholesterol, the neutral lipid dioleoylphosphatidylethanolamine and DNA. We show that nominally charge-neutral complexes coexist with free DNA, while excess cationic charge is necessary to protect all the genetic cargo. Such an extra-charge requirement diminishes as the molar fraction of neutral lipid in the bilayer increases. Furthermore, complexes with very different membrane composition and charge ratio exhibit the very same DNA protection ability. The relevance of results for transfection studies is discussed.
Aboveground biomass of functional groups in the ground layer of savannas under different fire frequencies
Authors: Cianciaruso Marcus Vinicius , Aurélio da Silva Igor , Batalha Marco Antônio
Published: May 2010

Savannas with different fire histories should have differences in aboveground biomass due to varying responses of functional groups. We investigated the effects of different fire frequencies on total aboveground biomass and also the biomass of functional groups (the tussock grass Tristachya leiostachya Nees, other grasses, small woody individuals) and dry biomass in savannas subjected to annual fires, biennial fires, and protected from fire for 12 years. Total biomass in the protected area was more than twice that of the annually burned area. T. leiostachya aboveground biomass was higher in the protected area than in annually and biennially burned areas, which were not different. Biomass of other grasses was lower in the protected area, whereas woody biomass values did not differ among areas. In the biennially burned and protected areas, we found a positive relationship between T. leiostachya and dry biomass. In the annually burned area, T. leiostachya biomass was negatively correlated with the biomass of other grasses and woody individuals. This negative correlation supports the idea that frequent fires favour the former, and may indicate an outcompeting effect. Knowledge not only about biomass but especially about its functional components is necessary to understand the processes and management consequences of different burning strategies.
Size-class structure and variation in seed and seedling traits in relation to population size of an endangered species Craigia yunnanensis (Tiliaceae)
Authors: Gao Zerui , Zhang Changqin , Milne Richard I.
Published: May 2010

Craigia yunnanensis W. W. Sm. & W. E. Evans is an endangered canopy tree species distributed in southern China and northern Vietnam. We located and surveyed six remnant populations, all from subtropical areas of Yunnan, China. These six populations contained between 6 and 167 adult trees in 2007, plus larger numbers of seedlings and resprouts from cut trunks. Bulk seed samples were collected from these populations and examined for 10 fitness traits (e.g. seed number, seed length, width and 1000-seed weight, germination in the controlled light and darkness conditions and nursery, seedling height, root collar diameter and dry weight). All traits differed significantly among populations, but only number of seeds per capsule was significantly correlated with population size. For some populations, germination capacity in light was significantly higher than that in darkness, indicating that canopy removal might promote regeneration from seed. Examination of population size-class structures in four C. yunnanesis populations determined that small seedlings and resprouts are abundant, although very few of these reach even the sapling stage. Hence, the remaining populations could be expanded and conserved by allowing a proportion of seedlings and resprouts to reach maturity. However, ex situ conservation, informed by data from the present study, is also advisable in case the remaining wild populations are lost.
Serpentine Science: Charles Kellaway and the Fluctuating Fortunes of Venom Research in Interwar Australia
Authors: Hobbins Peter G.
Published: May 2010

Australian medical research before the Second World War is predominantly viewed as an anodyne precursor to its conspicuous postwar successes. However, the expanding intellectual appeal and state support for local research after 1945 built upon scientific practices, networks, facilities and finances established between 1919 and 1939. Arguably the most prominent medical scientist working in Australia during this period was Charles Kellaway (1889?1952), director of Melbourne's Walter and Eliza Hall Institute from 1923 until 1944. Facing both financial challenges and a profoundly unsupportive intellectual climate, Kellaway instigated a major research programme into Australian snake venoms. These investigations garnered local and international acclaim, allowing Kellaway to speak as a significant scientific actor while fostering productive laboratory collaborations. The venom work spurred basic research in tissue injury, anaphylaxis and leukotriene pharmacology, yet delivered pragmatic clinical outcomes, particularly an effective antivenene. By selecting a problem of continuing public interest, Kellaway also stimulated wider engagement with science and initiated a pioneering ad hoc Commonwealth grant for medical research. In tracing his training, mentors and practices within the interwar milieu, this article argues that Kellaway's venom studies contributed materially to global biomedical developments and to the broader viability of medical research in Australia.
Joseph Maiden and the National and Transnational Circulation of Wattle Acacia spp.
Authors: Frawley Jodi
Published: May 2010

During the nineteenth century and in the early years of the twentieth century wattle was circulated by botanists, botanical institutions, interested individuals, commercial seedsmen and government authorities. Wattle bark was used in the production of leather and was the subject of debate regarding its commercial development and conservation in Australia. It was also trialled in many other locations including America, New Zealand, Hawaii and Russia. In the process, South Africa became a major producer of wattle bark for a global market. At the same time wattle was also promoted as a symbol of Australian nationalism. This paper considers this movement of wattles, wattle material and wattle information by examining the career of one active agent in these botanical transfers: Joseph Maiden. In doing so it demonstrates that these seemingly different uses of the wattle overlap transnational and national spheres.
Changes in composition and activity of soil microbial communities in peach and kiwifruit Mediterranean orchards under an innovative management system
Authors: Sofo Adriano , Celano Giuseppe , Ricciuti Patrizia , Curci Maddalena , Dichio Bartolomeo , Xiloyannis Cristos , Crecchio Carmine
Published: May 2010

The aim of this work was to evaluate the effects of 2 soil management systems, so called ‘innovative’ (INN) and ‘conventional’ (CON), on genetic and metabolic diversity of soil microbial communities of peach and kiwifruit orchards. INN system included minimum tillage, organic matter inputs from compost and cover crops, winter pruning, and adequate irrigation and fertilisation. CON system was characterised by conventional tillage, zero organic input, empirical pruning, strong chemical fertilisation, and excessive irrigation. After 4 years of treatments, soil samples were collected in different orchard sites. In peach and kiwifruit INN orchards, average fruit yields were significantly higher than in CON. INN orchards had a significantly higher total number of bacteria. The patterns of denaturing gradient gel electrophoresis of bacterial 16S rDNA/RNA from peach orchard showed differences between soils under drip emitters and along the inter-rows, whereas those from kiwifruit orchard clearly distinguished between INN and CON for both bacteria (16S rRNA) and fungi (18S rDNA/RNA). Shannon’s substrate diversity index, evaluated by Biolog® metabolic assay, was affected by soil treatment in peach orchard and by soil depth in kiwifruit orchard. Principal component analysis of Biolog® values clearly discriminated INN and CON soils of both orchards. The results revealed qualitative and quantitative changes of soil microbial communities in response to an innovative and sustainable soil management.
Tillage practices altered labile soil organic carbon and microbial function without affecting crop yields
Authors: Roper Margaret M. , Gupta V. V. S. R. , Murphy Daniel V.
Published: May 2010

A 7-year tillage experiment was conducted on a deep sand in the central wheat belt of Western Australia between 1998 and 2004 to evaluate the impact of tillage intensity [no-tillage (NT), conservation tillage (CT), and rotary tillage (RT)] on soil organic matter, microbial biomass and function, and crop yields in a wheat–lupin rotation. A fourth treatment (subterranean clover pasture, Pasture) with least soil disturbance was included as a comparison. By March 2004, total soil carbon (C) in NT and CT increased by 4.4 and 2.6 t/ha, respectively, to an average of 17.6 t/ha in the top 0.1 m of the soil profile. There was a loss of total soil C in RT (–0.5 t/ha), which was significant compared with the other 2 tillage treatments. Total soil C and nitrogen (N) contents in the pasture treatment were similar to those in NT and CT at the end of the experiment. Labile fractions of soil C responded more rapidly to tillage practice, with significant reductions by 2001 in light fraction C and dissolved organic C in the RT treatment compared with the other 3 treatments. The effect of RT on biology and function was seen early in the experiment and, compared with Pasture, NT, and CT, intense tillage in RT significantly reduced microbial biomass and cellulase activity in the surface 0.05 m by the third year of the experiment. However, at a depth of 0.05–0.10 m there were no significant differences between treatments. Grain yields in NT, CT, and RT were unaffected by tillage except in 2003, when lupin yield under RT (1.6 t/ha) was significantly less than under NT (2.0 t/ha) and CT (1.9 t/ha). Minimal differences between NT and CT are a reflection of the minimum disturbance in the CT treatment, although there were significant differences between CT and NT in microbial indices such as microbial quotient and metabolic quotient, suggesting a future divergence of these treatments.