bluuebunny/crossref_metadata_2025 huggingface dataset:
Chondrogenic differentiation of adipose tissue‐derived mesenchymal stem cells: Greater doses of growth factor are necessary
Authors: Kim Hye‐Joung , Im Gun‐Il
Published: November 2008

There have been controversies regarding the chondrogenic potential of adipose tissue‐derived mesenchymal stem cells (ATMSCs) compared with bone marrow‐derived mesenchymal stem cells (BMMSCs). The purpose of this study was to confirm the hypothesis that chondrogenesis can be achieved from ATMSCs comparable to that from BMMSCs by using greater dose of currently known chondrogenic growth factors. Chondrogenesis was induced from ATMSCs by culturing them in pellets under the following conditions: #1 without growth factors (negative control); #2 5 ng/mL of TGF‐β2; #3 5 ng/mL of TGF‐β2 and 100 ng/mL of IGF‐I; #4 15 ng/mL of TGF‐β2; #5 15 ng/mL of TGF‐β2 and 300 ng/mL of IGF‐I; #6 25 ng/mL of TGF‐β2; #7 25 ng/mL of TGF‐β2 and 500 ng/mL of IGF‐I. After 4 weeks of in vitro culture, the pellets were harvested for DNA quantification, analysis of the glycosaminoglycan content, reverse transcription, and real‐time PCR for collagen type I (COL1A1), collagen type II (COL2A1), and Sox‐9. Safranin‐O and immunohistochemical staining for type II collagen also were carried out, and histological grading was performed based on the findings. A combination of 25 ng/mL TGF‐β2 and 500 ng/mL IGF‐I produced results comparable to the positive control (BMMSCs treated with 5 ng/mL TGF‐β2) as demonstrated by DNA amount, GAG analysis, real‐time PCR, and histological findings. Although ATMSCs have lower chondrogenic potentials than BMMSCs, chondrogenesis comparable to BMMSCs can be induced from ATMSCs using a greater dose combination of growth factors. These results lend a further support to the application of ATMSCs for cartilage tissue engineering. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27: 612–619, 2009
Fuelwood, deforestation, and land degradation: 10 years of evidence from cebu province, the Philippines
Authors: Bensel Terrence
Published: November 2008

A major development concern of the 1970s and 1980s was ‘the other energy’ or ‘woodfuel crisis’. Woodfuel use in developing regions of Africa, Asia, and Latin America was believed to be a key factor in tropical deforestation, and the loss of forests was projected to result in widespread woodfuel shortages. In recent years, however, it has become apparent that woodfuel production is seldom a direct cause of deforestation (although it may be a by‐product), and that most woodfuel demand is met by trees and shrubs growing outside of forest areas. In addition, earlier predictions of serious woodfuel shortages have not materialized. But in some regions, including the Philippines, woodfuel use is still regularly pointed to as a primary cause of deforestation, and woodfuel shortages are still predicted for the immediate future. In particular, commercial woodfuel demand for household and commercial use is said to be contributing to over‐exploitation of forest resources. This paper examines the connections between commercial woodfuel demand and deforestation on the Island of Cebu in the central Philippines. Cebu is widely perceived as an environmental disaster area on the brink of ecological collapse, and tree cutting for woodfuel production is often blamed for contributing to this condition. In contrast, this paper will argue that environmental conditions on Cebu are improving, that tree planting and management is widespread among smallholder farmers and other landowners, and that commercial demand for woodfuel and other wood products is one of the main factors driving increased reforestation on the island. Copyright © 2008 John Wiley & Sons, Ltd.
Analysis of underivatized artemisinin and related sesquiterpene lactones by high‐performance liquid chromatography with ultraviolet detection
Authors: Ferreira Jorge F. S. , Gonzalez Javier M.
Published: November 2008

Introduction

Although high‐performance liquid chromatography with ultraviolet detection (HPLC‐PAD) is widely available, it has not been used for artemisinin (1) analysis because of the lack of UV absorption reported for this lactone. Increased Artemisia annua cultivation for production of 1 requires an affordable and reliable method to analyse 1 and its precursors dihydroartemisinic acid (2) and artemisinic acid (3) simultaneously from underivatized plant extracts.

Objective

To validate HPLC‐PAD for the quantification of underivatized artemisinin from A. annua and artemisinin‐based drugs.

Methodology

Dried A. annua leaves were extracted with petroleum ether, dried, reconstituted in acetonitrile, and analysed by HPLC‐PAD at 192 nm using an isocratic mobile phase (60:40, acetonitrile:0.1% acetic acid). HPLC‐PAD was evaluated through accuracy, precision, recovery and comparison with HPLC with evaporative light scattering detection (HPLC‐ELSD).

Results

HPLC‐PAD proved accurate, precise and reproducible for the direct quantification of 1 and related compounds, and was more sensitive than ELSD for most of the compounds tested. The limit of quantification of 1–3 from plants was 0.048, 0.024 and 0.008 g/100 g dry weight, respectively. Recoveries were over 98%, with good intra‐ and inter‐day repeatability. HPLC‐PAD correlated significantly (r2 = 0.99, p <0.001) with HPLC‐ELSD for artemisinin analysis. HPLC‐PAD was also reliable for the analysis of dihydroartemisinin, artesunate and artelinic acid.

Conclusion

HPLC with ultraviolet detection was validated for the quantification of underivatized 1, 2, and 3 from crude plant samples, and is readily applicable for the quality control of herbals and artemisinin‐related pharmaceutical compounds. Copyright © 2008 John Wiley & Sons, Ltd.
Transient reference values for impulse oscillometry for children aged 3–18 years
Authors: Nowowiejska Bożena , Tomalak Waldemar , Radliński Jakub , Siergiejko Grzegorz , Latawiec Wojciech , Kaczmarski Maciej
Published: November 2008

Impulse oscillometry (IOS) is a technique of assessing mechanical properties of respiratory system by means of measuring resistances and reactances in a number of frequencies during tidal breathing. It is especially useful in preschool children, however has also been validated in older children and adults. The aim of the present study was to construct equations describing normal values of oscillatory parameters in pediatric population of healthy polish children. Six hundred twenty‐six healthy children aged 3.1–18.9 years (278 boys and 348 girls) completed the study. Analysis revealed that body height was the best predictor and resistances are best described with exponential model while reactances with linear one, with correlation coefficient r reaching the value of 0.9. Oscillometric resistances decrease with height, while reactances increase. Reference values for children and adolescents will allow not only the interpretation of the measurement, but also will make possible to study changes of oscillometric indices during growth. Pediatr. Pulmonol. 2008; 43:1193–1197. © 2008 Wiley‐Liss, Inc.
Simulation of electronic density of states and optical properties of PbB4O7 by first‐principles DFT method
Authors: Wang Hui , Wang Yufang , Cao Xuewei , Zhang Lei , Feng Min , Lan Guoxiang
Published: November 2008

First‐principles calculations based on the density functional theory and the generalized gradient approximation were carried out to systematically investigate the electronic structure and linear optical properties of lead tetraborate (PbB4O7; PTB) single crystals. An indirect band gap of 4.34 eV is obtained. The valence band top is at the X‐point and the conduction band is at the Γ‐point. The calculated total and partial densities of states indicate that the top valence band is constructed from O 2p states and the low conduction band mainly consists of Pb 6p states. The optical absorption spectra show several prominent structures but with very small directional anisotropy. PTB crystals have a higher refractive index but a small birefringence. The calculated frequency‐dependent refractive index is in good agreement with experimental data. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A versatile method for stable carbon isotope analysis of carbohydrates by high‐performance liquid chromatography/isotope ratio mass spectrometry
Authors: Boschker H. T. S. , Moerdijk‐Poortvliet T. C. W. , van Breugel P. , Houtekamer M. , Middelburg J. J.
Published: November 2008

We have developed a method to analyze stable carbon isotope (13C/12C) ratios in a variety of carbohydrates using high‐performance liquid chromatography/isotope ratio mass spectrometry (HPLC/IRMS). The chromatography is based on strong anion‐exchange columns with low strength NaOH eluents. An eluent concentration of 1 mM resulted in low background signals and good separation of most of the typical plant neutral carbohydrates. We also show that more strongly bound carbohydrates such as acidic carbohydrates can be separated by inclusion of NO as an inorganic pusher ion in the eluent. Analyses of neutral carbohydrate concentrations and their stable carbon isotope ratios are shown for plant materials and marine sediment samples both at natural abundance and for 13C‐enriched samples. The main advantage of HPLC/IRMS analysis over traditional gas chromatography based methods is that no derivatization is needed resulting in simple sample treatment and improved accuracy and reproducibility. Copyright © 2008 John Wiley & Sons, Ltd.
The typical structure of graphs without given excluded subgraphs
Authors: Balogh József , Bollobás Béla , Simonovits Miklós
Published: November 2008

Let $ {\cal L}$ be a finite family of graphs. We describe the typical structure of $ {\cal L}$‐free graphs, improving our earlier results (Balogh et al., J Combinat Theory Ser B 91 (2004), 1–24) on the Erdős–Frankl–Rödl theorem (Erdős et al., Graphs Combinat 2 (1986), 113–121), by proving our earlier conjecture that, for $ p = p ({\cal L}) = {\rm min}_L \in {\cal L} \chi (L) - 1 $, the structure of almost all $ {\cal L}$‐free graphs is very similar to that of a random subgraph of the Turán graph Tn,p. The “similarity” is measured in terms of graph theoretical parameters of $ {\cal L}$.© 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2009
Sky‐sourced sustainability—the potential environmental advantages of building tall
Authors: Leung Luke , Weismantle Peter
Published: November 2008

Utilizing the earth and near‐grade environment as a source of energy has historically been a common practice. Beyond solar and wind, designers do not usually look towards the sky as the source of additional benefits. The objective of this paper was to make tall‐building designers more aware of the additional sources of sustainability ‘in the sky’; how these sources change with altitude; and how this knowledge can benefit the design, construction and operation of tall buildings.

Exterior environmental factors including temperature, presssure/air density, solar, wind and moisture, and their relationships with altitude are discussed. Selected approaches are suggested on how to benefit from them. Since current energy codes and ‘green’ building standards do not address the issue of enrironmental variations with altitude, the sky has potential to offer unique energy‐saving opportunities and possibly add to the quantified sustainability of a tall building.

Where possible, a speculative 1‐km (3281 ft) tall tower in Dubai is used as an example for illustration. Copyright © 2008 John Wiley & Sons, Ltd.
Tube Formation in Nanoscale Materials
Authors: Yan Chenglin , Liu Jun , Liu Fei , Wu Junshu , Gao Kun , Xue Dongfeng
Published: November 2008

The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb2O5nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities.
Structural Evolution During Formation and Filling of Self-patterned Nanoholes on GaAs (100) Surfaces
Authors: Sablon KA , Wang Zh M , Salamo GJ , Zhou Lin , Smith David J
Published: November 2008

Nanohole formation on an AlAs/GaAs superlattice gives insight to both the “drilling” effect of Ga droplets on AlAs as compared to GaAs and the hole-filling process. The shape and depth of the nanoholes formed on GaAs (100) substrates has been studied by the cross-section transmission electron microscopy. The Ga droplets “drill” through the AlAs layer at a much slower rate than through GaAs due to differences in activation energy. Refill of the nanohole results in elongated GaAs mounds along the [01−1] direction. As a result of capillarity-induced diffusion, GaAs favors growth inside the nanoholes, which provides the possibility to fabricate GaAs and AlAs nanostructures.
Visualization of Bile Homeostasis Using 1H‐NMR Spectroscopy as a Route for Assessing Liver Cancer
Authors: Nagana Gowda G. A. , Shanaiah Narasimhamurthy , Cooper Amanda , Maluccio Mary , Raftery Daniel
Published: November 2008

Changes in bile synthesis by the liver or alterations in the enterohepatic circulation due to a variety of etiological conditions may represent a novel source of liver disease‐specific biomarkers. Bile from patients with liver diseases exhibited significant changes in the levels of glycine‐ and taurine‐conjugated bile acids, phospholipids, cholesterol and urea relative to non‐liver disease controls. Cholangiocarcinoma and non‐malignant liver diseases (NMLD) showed the most significant alterations. Further, hepatocellular carcinoma (HCC) could be differentiated from NMLD (p = 0.02), as well as non‐liver disease controls (p = 0.02) based on the amounts of bile acids, phospholipids and/or cholesterol. HCC also differed with cholangiocarcinoma although not significantly. Urea increases somewhat in non‐malignant liver disease relative to non‐liver disease controls, while the bile acids, phospholipids and cholesterol all decrease significantly. The ratio between some major bile metabolites also distinguished NMLD (p = 0.004–0.01) from non‐liver disease controls. This snapshot view of bile homeostasis, is obtainable from a simple nuclear magnetic resonance (NMR) approach and demonstrates the enormous opportunity to assess liver status, explore biomarkers for high risk diseases such as cancers and improve the understanding of normal and abnormal cellular functions.
Acute internalization of gap junctions in vascular endothelial cells in response to inflammatory mediator‐induced G‐protein coupled receptor activation
Authors: Baker Susan M. , Kim Namho , Gumpert Anna M. , Segretain Dominique , Falk Matthias M.
Published: November 2008

During the inflammatory response, activation of G‐protein coupled receptors (GPCRs) by inflammatory mediators rapidly leads to inhibition of gap junction intercellular communication (GJIC); however, the steps that lead to this inhibition are not known. Combining high‐resolution fluorescence microscopy and functional assays, we found that activation of the GPCRs PAR‐1 and ETA/Bby their natural inflammatory mediator agonists, thrombin and endothelin‐1, resulted in rapid and acute internalization of gap junctions (GJs) that coincided with the inhibition of GJIC followed by increased vascular permeability. The endocytosis protein clathrin and the scaffold protein ZO‐1 appeared to be involved in GJ internalization, and ZO‐1 was partially displaced from GJs during the internalization process. These findings demonstrate that GJ internalization is an efficient mechanism for modulating GJIC in inflammatory response.
DOES EDUCATION MEDIATE THE RELATIONSHIP BETWEEN IQ AND AGE OF FIRST BIRTH? A BEHAVIOURAL GENETIC ANALYSIS
Authors: NEISS MICHELLE , ROWE DAVID C. , RODGERS JOSEPH L.
Published: November 2008

This study presents a multivariate behavioural genetic analysis of the relationship between education, intelligence and age of first birth. Analyses investigated the mediational role of education in explaining the relationship between intelligence and age of first birth at both the phenotypic and behavioural genetic level. The data come from the National Longitudinal Survey of Youth (NLSY), a nationally representative survey that included genetically informative full- and half-sibling pairs (n=1423 pairs). Respondents were aged 14 to 22 when contacted in 1979. Heritability estimates were 0·32, 0·50 and 0·06 for IQ, education and age of first birth, respectively. Shared environment estimates were 0·35, 0·23 and 0·20 respectively. Common genetic and shared environmental factors were substantial in explaining the relationship between intelligence and education, and also education and age of first birth. Education partially mediated the relationship between intelligence and age of first birth only in the phenotypic analyses. After considering the genetic and shared environmental factors that influence all three variables, evidence for mediation was less convincing. This pattern of results suggests that the apparent mediational role of education at the phenotypic level is in fact the result of underlying genetic and shared environmental influences that affect education, IQ and age of first birth in common.
The Beastie Boys: Jews in whiteface
Authors: STRATTON JON
Published: November 2008

The Beastie Boys are usually described as the white hip hop group who helped break rap to a broad-based white audience. Rarely is it acknowledged that the Beasties all came from Jewish backgrounds. This article examines the implications of the Beastie Boys’ Jewishness. The Beasties can be placed in a long history of Jewish entertainers reworking black music for white American audiences. By the 1980s, Jews in the United States had been assimilated into whiteness, yet it is clear that the memory of discrimination lived on. The members of the Beasties played with whiteness – performed in whiteface – while being very aware of their own Jewishness and the implications of this. With the advice and mentoring of African American Russell Simmons and the Jewish Rick Rubin, the group gained respect in the black community as legitimate rappers and then set out to perform as uncivil rock performers for white audiences. This article argues that the Beasties’ Jewishness was central to their success as the group that brought rap to a mainstream white American audience.
NEUROECONOMICS: A CRITICAL RECONSIDERATION
Authors: Harrison Glenn W.
Published: November 2008

Understanding more about how the brain functionsshouldhelp us understand economic behaviour. But some would have us believe that it has done this already, and that insights from neuroscience have already provided insights in economics that we would not otherwise have. Much of this is just academic marketing hype, and to get down to substantive issues we need to identify that fluff for what it is. After we clear away the distractions, what is left? The answer is that a lot is left, but it is still all potential. That is not a bad thing, or a reason to stop the effort, but it does point to the need for a serious reconsideration of what neuroeconomics is and what passes for explanation in this literature. I argue that neuroeconomics can be a valuable field, but not the way it is being developed and “sold” now. The same is true more generally of behavioural economics, which shares many of the methodological flaws of neuroeconomics.
NO REVOLUTION NECESSARY: NEURAL MECHANISMS FOR ECONOMICS
Authors: Craver Carl F. , Alexandrova Anna
Published: November 2008

We argue that neuroeconomics should be a mechanistic science. We defend this view as preferable both to a revolutionary perspective, according to which classical economics is eliminated in favour of neuroeconomics, and to a classical economic perspective, according to which economics is insulated from facts about psychology and neuroscience. We argue that, like other mechanistic sciences, neuroeconomics will earn its keep to the extent that it either reconfigures how economists think about decision-making or how neuroscientists think about brain mechanisms underlying behaviour. We discuss some ways that the search for mechanisms can bring about such top-down and bottom-up revision, and we consider some examples from the recent neuroeconomics literature of how varieties of progress of this sort might be achieved.
THE SYLLOGISM OF NEURO-ECONOMICS
Authors: Padoa-Schioppa Camillo
Published: November 2008

If neuroscience is to contribute to economics, it will do so by the way of psychology. Neural data can and do lead to better psychological theories, and psychological insights can and do lead to better economic models. Hence, neurosciencecanin principle contribute to economics. Whether it actuallywilldo so is an empirical question and the jury is still out. Economics currently faces theoretical and empirical challenges analogous to those faced by physics at the turn of the twentieth century and ultimately addressed by quantum theory. If “quantum economics” will emerge in the coming decades, it may well be founded on such concepts as cognitive processes and brain activity.
Therapeutic potential of HMGB1-targeting agents in sepsis
Authors: Wang Haichao , Zhu Shu , Zhou Rongrong , Li Wei , Sama Andrew E.
Published: November 2008

Sepsis refers to a systemic inflammatory response syndrome resulting from a microbial infection. The inflammatory response is partly mediated by innate immune cells (such as macrophages, monocytes and neutrophils), which not only ingest and eliminate invading pathogens but also initiate an inflammatory response upon recognition of pathogen-associated molecular patterns (PAMPs). The prevailing theories of sepsis as a dysregulated inflammatory response, as manifested by excessive release of inflammatory mediators such as tumour necrosis factor and high-mobility group box 1 protein (HMGB1), are supported by extensive studies employing animal models of sepsis. Here we review emerging evidence that support extracellular HMGB1 as a late mediator of experimental sepsis, and discuss the therapeutic potential of several HMGB1-targeting agents (including neutralising antibodies and steroid-like tanshinones) in experimental sepsis.
Antimicrobial resistance in swine production
Authors: Aarestrup Frank M. , Oliver Duran C. , Burch David G. S.
Published: November 2008

Large amounts of antimicrobial agents are still being used in modern swine production in many countries around the world. This facilitates the emergence and development of antimicrobial resistance. Bacteria causing infections in swine have in several cases acquired resistance to a number of the agents most commonly used for treatment, making it difficult to predict the efficacy of different antimicrobial agents without prior susceptibility testing. This review gives an overview of recent susceptibility data from different parts of the world and discusses the importance of the development of resistance not only in the treatment of infections in swine but also taking into account the human health implications of antimicrobial resistance.
Aerosol retrieval from two‐wavelength backscatter and one‐wavelength polarization lidar measurement taken during the MR01K02 cruise of the R/V Mirai and evaluation of a global aerosol transport model
Authors: Nishizawa Tomoaki , Okamoto Hajime , Takemura Toshihiko , Sugimoto Nobuo , Matsui Ichiro , Shimizu Atsushi
Published: November 2008

Using two‐wavelength lidar with one‐wavelength depolarization measurement installed on the research vessel Mirai, we retrieved vertical distributions of extinction coefficients of water‐soluble, sea‐salt, and dust particles at 532 nm. In the retrieval, the mode radii, standard deviations, and refractive indexes for each aerosol component are prescribed; the retrieval uncertainties due to spherical assumption in our dust model are estimated to be 30–50%. The ship‐based measurements were conducted in the western Pacific Ocean near Japan from 14 to 27 May 2001. For the analysis, we applied two‐wavelength lidar algorithms to the three‐channel lidar data, i.e., for signal strengths at 532 and 1064 nm and the total depolarization ratio at 532 nm. Water‐soluble and sea‐salt particles occurred below 1 km, whereas air masses dominated by water‐soluble and dust particles were sometimes found above 1 km. We also investigated the correlation of sea‐salt extinction coefficient with surface wind velocity for various altitudes. A positive correlation was found at low altitude, but no correlation was indicated at high altitude. We also compared the extinction coefficients of water‐soluble and sea‐salt particles directly under cloud bottom with those in clear‐sky. Below clouds, the extinction coefficients of water‐soluble and sea‐salt particles were 1.6 and 1.4 times larger, respectively, than those in clear sky; this could be explained by hygroscopic growth using Hänel theory. Finally, we evaluated the global aerosol transport model SPRINTARS using the retrieved aerosol properties and measured lidar signals. The model underestimated sea salt and overestimated dust, although the general patterns agreed with the observed patterns.
The smoke episode in Buenos Aires, 15–20 April 2008
Authors: Berbery Ernesto Hugo , Ciappesoni Hector C. , Kalnay Eugenia
Published: November 2008

The smoke that affected the city of Buenos Aires and its suburbs (approximate population, 13M) in mid April 2008 was an extreme event without historical precedent. The episode resulted in an increase of health problems among the population (respiratory problems, eye irritation) and, due to poor visibility, led to hazardous driving conditions and accidents that forced the intermittent closure of major highways. The origin of the smoke was traced to pasture burning in the La Plata River delta, to the northwest of Buenos Aires. Unfortunately, the increased shifting of livestock to the La Plata River delta may result in more common smoke episodes due to associated biomass burning practices. We clarify the mechanisms that resulted in this extreme episode, including the contribution of the La Plata River local circulations to the intensity of the event. We further show its high predictability using high resolution regional model simulations and forecasts. Our results suggest that a high resolution regional model could be used to monitor and predict several days in advance the atmospheric transport of smoke. These results could have policy implications, as preventive measures on biomass burning could be put in effect when smoke from the fires is predicted to affect a densely populated area.
Phreatomagmatic explosions of rhyolitic magma: Experimental and field evidence
Authors: Austin‐Erickson A. , Büttner R. , Dellino P. , Ort M. H. , Zimanowski B.
Published: November 2008

Experimental studies on explosive molten fuel‐coolant interaction (MFCI) using basaltic melt compositions and water as the coolant have provided insight into the physical processes of basaltic and andesitic phreatomagmatic volcanism. Abundant field evidence indicates that rhyolitic and dacitic phreatomagmatism occurs in nature, but it has not been possible until now to generate laboratory MFCI explosions from the interaction between high‐silica melts and water under laboratory conditions. The high viscosity of these melts apparently prevents formation of an effective hydrodynamic premix of melt and water, the documented precursor of experimental explosive MFCI caused by mafic melts. Our new experiments utilized samples from a rhyolitic tuff ring volcano in Mexico (Tepexitl). An experimental approach was developed, in which premixing conditions were generated by mechanical deformation of the melt, leading to brittle‐type fragmentation at the melt‐water interface. Physical measurements recorded during laboratory explosion provide quantitative evidence for rhyolitic explosive MFCI. Additionally, a comparison of experimentally produced particles with natural ones from Tepexitl deposits show nearly identical chemical/mineralogical composition, grain size, and grain morphology. Detailed textural analysis confirmed the presence of phreatomagmatically produced particles in both experimental and natural analog particles. The results from this series of experiments indicate that under natural conditions, stress‐induced magma fracturing can lead to a critical magma‐water‐interface growths and trigger phreatomagmatic explosions of high‐silica magma. The water source for these eruptions may include shallow aquifers, surface water bodies, strong precipitation, and intrusion into ice or wet, unconsolidated sediments.
Trends and interannual variability in surface UVB radiation over 8 to 11 years observed across the United States
Authors: Hicke Jeffrey A. , Slusser James , Lantz Kathleen , Pascual F. G.
Published: November 2008

The United States Department of Agriculture UVB Monitoring and Research Program maintains a network of Yankee Environmental Systems surface UVB‐1 meters distributed throughout the United States. We analyzed behavior of surface UVB radiation (280–320 nm) over 8 to 10 years measured at eight stations within this network that were selected because of their early deployment (ranging from 1995 to 1997). These eight stations represent different climates, latitudes, and land cover types. We characterized differences in instrument sensitivity and drift through a methodology that utilized regular laboratory calibrations of field instruments and calibration of standard meters to spectroradiometers. From 3‐minute observations, we computed mean annual and mean monthly irradiances at each site to study trends and interannual variability in UVB irradiance. Annual irradiance changes ranged from −5% per decade to +2% per decade across the sites. Confidence intervals were computed with a statistical model that included autocorrelation and measurement uncertainty. Resulting 95% confidence intervals were large and included 0, partly as a result of the short time series. We calculated trends at each site for individual months (for January, February, etc.), which are important for assessing effects on human health, crops, and other organisms whose sensitivity to UVB exposure changes seasonally. Positive and negative monthly trends of different magnitudes were measured, although trends in most months at most sites were not statistically significant from 0. The largest absolute changes were generally in spring, summer, and fall, and large relative trends occurred in winter in most locations compared with other seasons. Interannual variability of surface UVB radiation was 2% to 5% of the mean. Our study illustrates that, using a well‐calibrated instrument record, the 10 years beginning around 1995 did not show significant trends in surface UVB irradiance at stations across the United States. Our observed range of trends occurred during a period of generally increasing midlatitude column ozone, suggesting that changing cloud, aerosol, and snow conditions were responsible for driving surface radiation variability in addition to ozone trends.
Arctic epishelf lakes as sentinel ecosystems: Past, present and future
Authors: Veillette Julie , Mueller Derek R. , Antoniades Dermot , Vincent Warwick F.
Published: November 2008

Ice shelves are a prominent but diminishing feature of the northern coastline of Ellesmere Island in the Canadian High Arctic (latitude 82–83°N). By blocking embayments and fiords, this thick coastal ice can create epishelf lakes, which are characterized by a perennially ice‐capped water column of freshwater overlying seawater. The goal of this study was to synthesize new, archived, and published data on Arctic epishelf lakes in the context of climate change. Long‐term changes along this coastline were evaluated using historical reports, cartographic analysis, RADARSAT imagery, and field measurements. These data, including salinity‐temperature profiling records from Disraeli Fiord spanning 54 years, show the rapid decline and near disappearance of this lake type in the Arctic. Salinity‐temperature profiling of Milne Fiord, currently blocked by the Milne Ice Shelf, confirmed that it contained an epishelf lake composed of a 16‐m thick freshwater layer overlying seawater. A profiling survey along the coast showed that there was a continuum of ice‐dammed lakes from shallow systems dammed by multiyear landfast sea ice to deep epishelf lakes behind ice shelves. The climate warming recently observed in this region likely contributed to the decline of epishelf lakes over the last century, and the air temperature trend predicted for the Arctic over the next several decades implies the imminent loss of this ecosystem type. Our results underscore the distinctive properties of coastal ice‐dammed lakes and their value as sentinel ecosystems for the monitoring of regional and global climate change.
It's life, but just as we know it
Authors: Greener Mark
Published: November 2008

A consensus definition of life remains elusive
Age-Dependent Regenerative Responses in the Striatum and Cortex after Hypoxia-Ischemia
Authors: Zhu Changlian , Qiu Lin , Wang Xiaoyang , Xu Falin , Nilsson Michael , Cooper-Kuhn Christiana , Kuhn H Georg , Blomgren Klas
Published: November 2008

Regenerative responses after hypoxia-ischemia (HI) were investigated in the immature (P9) and juvenile (P21) mouse striatum and cortex by postischemic 5-bromo-2-deoxyuridine labeling and phenotyping of labeled cells 4 weeks later. HI stimulated the formation of new cells in striatum and cortex in immature, growing brains (P9), but when brain growth was finished (P21) proliferation could be stimulated only in striatum, not in cortex. However, the relative increase was higher in P21 (460%) than P9 striatum (50%), though starting from a lower level at P21. Starting from this lower level, HI-induced proliferation in P21 striatum reached the same level as in P9 striatum, but not higher. Phenotyping revealed that low levels of neurogenesis were still present in nonischemic P9 cortex and striatum, but only in striatum at P21. Ischemia-induced neurogenesis was found only in P9 striatum. Ischemia-induced gliogenesis occurred in P9 and P21 striatum as well as P9 cortex, but not in P21 cortex. Hence, the regenerative response was stronger in striatum than cortex, and stronger in P9 than P21 cortex. The biggest ischemia-induced change was the 49-fold increase in P21 striatal microglia, and this was accompanied by increased inflammation, as judged by the size and numbers of CCL2- and interleukin-18-positive cells.
Overexpression of Mitochondrial Hsp70/Hsp75 in Rat Brain Protects Mitochondria, Reduces Oxidative Stress, and Protects from Focal Ischemia
Authors: Xu Lijun , Voloboueva Ludmila A , Ouyang YiBing , Giffard Rona G
Published: November 2008

Mitochondria are known to be central to the cell's response to ischemia, because of their role in energy generation, in free radical generation, and in the regulation of apoptosis. Heat shock protein 75 (Hsp75/Grp75/mortalin/TRAP1) is a member of the HSP70 chaperone family, which is targeted to mitochondria. Overexpression of Hsp75 was achieved in rat brain by DNA transfection, and expression was observed in both astrocytes and neurons. Rats were subjected to 100 mins middle cerebral artery occlusion followed by assessment of infarct volume, neurological score, mitochondrial function, and levels of oxidative stress at 24 h reperfusion. Overexpression of Hsp75 reduced infarct area from 44.6%±21.1% to 25.7%±12.1% and improved neurological outcome significantly. This was associated with improved mitochondrial function as shown by protection of complex IV activity, marked reduction of free radical generation detected by hydroethidine fluorescence, reduction of lipid peroxidation detected by 4-hydroxy-2-nonenol immunoreactivity, and increased preservation of ATP levels. This suggests that targeting mitochondria for protection may be a useful strategy to reduce ischemic brain injury.
PI3Kγ controls oxidative bursts in neutrophils via interactions with PKCα and p47phox
Authors: Lehmann Katja , Müller Jörg P. , Schlott Bernhard , Skroblin Philipp , Barz Dagmar , Norgauer Johannes , Wetzker Reinhard
Published: November 2008

Neutrophils release reactive oxygen species (ROS) as part of the innate inflammatory immune response. Phosphoinositide 3-kinase γ (PI3Kγ), which is induced by the bacterial peptide N-formylmethionyl-leucyl-phenylalanine (fMLP), has been identified as an essential intracellular mediator of ROS production. However, the complex signalling reactions that link PI3Kγ with ROS synthesis by NADPH oxidase have not yet been described in detail. We found that activation of neutrophils by fMLP triggers the association of PI3Kγ with protein kinase Cα (PKCα). Specific inhibition of PI3Kγ suppresses fMLP-mediated activation of PKCα activity and ROS production, suggesting that the protein kinase activity of PI3Kγ is involved. Our data suggest that the direct interaction of PI3Kγ with PKCα forms a discrete regulatory module of fMLP-dependent ROS production in neutrophils.
High-resolution characterization of defects in oxide thin films
Authors: Nikiforov Maxim N. , Brukman Matthew J. , Bonnell Dawn A.
Published: November 2008

Nanometer sized defects in thin HfOx films are detected by atomic force microscopy facilitated leakage current measurements. Differences in the electrical properties of individual defects were distinguished. The effects of two mechanisms that localize the tip-sample interaction and increase spatial resolution were calculated. The expected increase in tip-sample current due to stress induced phase transformations and band gap narrowing has been calculated, and a behavior diagram is presented that shows the pressure necessary to generate a detectable current increase as a function of tip radius.
Study of 1,3-dimethylimidazolium chloride with electronic structure methods and force field approaches
Authors: Krekeler Christian , Schmidt Jochen , Zhao Yuan Yuan , Qiao Baofu , Berger Robert , Holm Christian , Delle Site Luigi
Published: November 2008

The 1,3-dimethyl imidazolium chloride [MMIM]Cl is an example of ionic liquid and frequently studied in literature. In this article [MMIM]Cl is studied using an ab initio method [second order Møller–Plesset perturbation theory (MP2), density functional theory (DFT)] and classical force field approach with the aim of looking at some properties on different scales. Selected properties are studied with the different methods and compared to each other. The comparison between the results obtained with MP2 and the DFT approach allows us to comment on the validity of this latter and thus on its employment in larger systems. On the other hand, the comparison between the DFT results and those of the classical approach allows us to test the reproducibility of electrostatic properties by this latter approach. As the results show the used DFT setup is rather satisfactory, while the classical force fields are describing the electrostatic properties in an insufficient way. A revision (improvement) of the classical force fields is at this stage necessary in order to capture the electrostatic properties in a proper way.
Electrical tuning of dc bias induced acoustic resonances in paraelectric thin films
Authors: Noeth Andreas , Yamada Tomoaki , Tagantsev Alexander K. , Setter Nava
Published: November 2008

A theoretical model for the dc bias dependence of induced acoustic resonances in paraelectric materials is presented. The field dependent piezoelectric constitutive equations were derived from the Landau free energy expansion with respect to the ferroelectric part of the polarization P. To derive the field dependent coefficients correctly, we demonstrate that it is important to take both linear and nonlinear electrostriction as well as the background permittivity into account. Two different resonator geometries, corresponding to the thickness excitation (TE) and the lateral field excitation (LFE) modes, are discussed and compared. In the TE mode the resonance frequency is expected to be much stronger dc bias dependent than the antiresonance frequency. In the LFE mode, both resonance and antiresonance frequencies may exhibit comparable dc bias dependences. In this case the antiresonance frequency shows a stronger tuning with increasing dc bias than the resonance frequency. We model the behavior of the field dependent acoustic resonances in BaxSr1−xTiO3 thin films addressing different compositions and orientations of the films. Our theoretical model corroborates the experimental results available in the literature.
First-principles calculation of defect formation energies and electronic properties in stannate pyrochlores
Authors: Chen Z. J. , Xiao H. Y. , Zu X. T. , Gao F.
Published: November 2008

The electronic structures and defect formation energies for a series of stannate pyrochlores Ln2Sn2O7 (Ln=La, Pr, Nd, Sm, Gd, Tb, Ho, Er, Lu, and Y) have been investigated using the first-principles total energy calculations. The calculated results show that Ln-site cation ionic radius, x-O48f, lattice constant and the covalency of the ⟨Sn–O48f⟩ bond have a significant affect on the defect formation energies. The cation-antisite defect has the lowest formation energy, as compared with that of other defects, indicating that cation disorder causes local oxygen disordering. The present studies suggest that Lu2Sn2O7 is the most resistant to ion beam-induced amorphization. The electronic structure calculations reveal that Ln2Sn2O7 compounds have direct band gaps of 2.64–2.95 eV at the Γ point in the Brillouin zone.
Molecular dynamics simulations of thermal resistance at the liquid-solid interface
Authors: Kim Bo Hung , Beskok Ali , Cagin Tahir
Published: November 2008

Heat conduction between parallel plates separated by a thin layer of liquid Argon is investigated using three-dimensional molecular dynamics (MD) simulations employing 6-12 Lennard-Jones potential interactions. Channel walls are maintained at specific temperatures using a recently developed interactive thermal wall model. Heat flux and temperature distribution in nanochannels are calculated for channel heights varying from 12.96to3.24nm. Fourier law of heat conduction is verified for the smallest channel, while the thermal conductivity obtained from Fourier law is verified using the predictions of Green-Kubo theory. Temperature jumps at the liquid/solid interface, corresponding to the well known Kapitza resistance, are observed. Using systematic studies thermal resistance length at the interface is characterized as a function of the surface wettability, thermal oscillation frequency, wall temperature, thermal gradient, and channel height. An empirical model for the thermal resistance length, which could be used as the jump coefficient of a Navier boundary condition, is developed. Temperature distribution in nanochannels is predicted using analytical solution of continuum heat conduction equation subjected to the new temperature jump condition. Analytical predictions are verified using MD simulations.
Capacitance-voltage characterization of GaAs–Al2O3 interfaces
Authors: Brammertz G. , Lin H.-C. , Martens K. , Mercier D. , Sioncke S. , Delabie A. , Wang W. E. , Caymax M. , Meuris M. , Heyns M.
Published: November 2008

The authors apply the conductance method at 25 and 150°C to GaAs–Al2O3 metal-oxide-semiconductor devices in order to derive the interface state distribution (Dit) as a function of energy in the bandgap. The Dit is governed by two large interface state peaks at midgap energies, in agreement with the unified defect model. S-passivation and forming gas annealing reduce the Dit in large parts of the bandgap, mainly close to the valence band, reducing noticeably the room temperature frequency dispersion. However the midgap interface state peaks are not affected by these treatments, such that Fermi level pinning at midgap energies remains.
Size-independent residual magnetic moments of colloidal Fe3O4-polystyrene nanospheres detected by ac susceptibility measurements
Authors: Chen Du-Xing , Sanchez Alvaro , Xu Hong , Gu Hongchen , Shi Donglu
Published: November 2008

Complex ac susceptibility of magnetic colloids of nanospheres, each consisting of Fe3O4 nanoparticles densely and uniformly embedded in a polystyrene matrix, is measured as a function of frequency. A data analysis based on a model and the directly measured size distribution shows that each spherical aggregate of nanoparticles carries a small residual magnetic moment, whose average is basically independent of the sphere size. The mentioned model assumes that magnetic spheres undergo rotational Brownian motions obeying Debye’s theory and nanoparticles undergo Néel magnetization rotations. A discussion is made on the superparamagnetism and the nanoparticle interactions in the present case, in order to justify the applicability of the model and to look for the mechanism of the detected sphere-size independent magnetic moment.
Real-time processing for Fourier domain optical coherence tomography using a field programmable gate array
Authors: Ustun Teoman E. , Iftimia Nicusor V. , Ferguson R. Daniel , Hammer Daniel X.
Published: November 2008

Real-time display of processed Fourier domain optical coherence tomography (FDOCT) images is important for applications that require instant feedback of image information, for example, systems developed for rapid screening or image-guided surgery. However, the computational requirements for high-speed FDOCT image processing usually exceeds the capabilities of most computers and therefore display rates rarely match acquisition rates for most devices. We have designed and developed an image processing system, including hardware based upon a field programmable gated array, firmware, and software that enables real-time display of processed images at rapid line rates. The system was designed to be extremely flexible and inserted in-line between any FDOCT detector and any Camera Link frame grabber. Two versions were developed for spectrometer-based and swept source-based FDOCT systems, the latter having an additional custom high-speed digitizer on the front end but using all the capabilities and features of the former. The system was tested in humans and monkeys using an adaptive optics retinal imager, in zebrafish using a dual-beam Doppler instrument, and in human tissue using a swept source microscope. A display frame rate of 27 fps for fully processed FDOCT images (1024 axial pixels×512 lateral A-scans) was achieved in the spectrometer-based systems.