bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamics of Soil Surface Bulk Density: Role of Water Table Elevation and Rainfall Duration
Authors: Augeard B. , Bresson L. M. , Assouline S. , Kao C. , Vauclin M.
Published: January 2008

Measurements of soil bulk density profiles combined with thin‐section analysis have been suggested to assess the structural seedbed degradation caused by rainfall. The effects of water table elevation and rainfall duration on surface sealing and seedbed slumping were studied on a repacked silt loam soil. Two initial water table elevations (0.3 and 0.7 m below the soil surface) and three simulated rainfall durations (15, 30, and 40 min at 30.5 mm h−1 followed by 180 min at 7 mm h−1) were used. Seedbed bulk density profiles were generated using x‐radiography of resin‐impregnated soil slices. Macroporosity measurements using image analysis and thin‐section observations showed that infilling of eroded particles in interaggregate voids and compaction of the infilled particles were the main sealing processes. Below the seal, the seedbed exhibited coalescence and welding of aggregates into larger units, which affected mainly macroporosity. A model of sealing, exponential decrease in bulk density with depth, and slumping, linear increase in bulk density with depth, adequately reproduced the measured bulk density profiles (regression RMSE range 0.057–0.106 Mg m−3). The change in surface bulk density increased with rainfall duration, whereas this factor did not significantly affect slumping. The highest initial water table elevation led to the highest soil surface and internal seedbed bulk densities. It was suggested that high values of soil water content led to a decrease in aggregate cohesion. Moreover, the number of wetting and drying cycles and the water content during these cycles were shown to increase the magnitude of slumping.
Agroforestry and Grass Buffer Effects on Pore Characteristics Measured by High‐Resolution X‐ray Computed Tomography
Authors: Udawatta Ranjith P. , Gantzer Clark J. , Anderson Stephen H. , Garrett Harold E.
Published: January 2008

Agroforestry and grass buffers can improve infiltration and reduce runoff from row‐crop agriculture. The objective of this study was to examine buffer effects on soil porosity using high‐resolution x‐ray computed tomography (CT). Treatments studied were agroforestry buffer, grass buffer, and row crop (RC) on a Putnam silt loam (fine, smectitic, mesic Vertic Albaqualf). A no‐till corn (Zea mays L.)‐soybean [Glycine max (L.) Merr.] rotation was established in 1991, with buffers implemented in 1997. Agroforestry buffers, 4.5 m wide and 36.5 m apart, consisted of pin oak (Quercus palustris Münchh.) trees planted among redtop (Agrostis gigantea Roth) and brome (Bromus spp.) grasses and birdsfoot trefoil (Lotus corniculatus L.). Two replicates of intact soil cores (76‐mm diam. by 76‐mm long) were collected from the 0‐ to 100‐mm depth. Cores were scanned at a voxel size of 73 by 73 by 84 μm. Images were analyzed with Three‐Dimensional Medial Axis (3DMA) software. The average pore paths for grass and agroforestry buffer samples were three and five times greater, respectively, than for RC. On average, buffer samples had a 33% higher characteristic coordination number than RC samples. Buffer samples had a higher characteristic path length constant (2.18 times the RC treatment) and an average lower path tortuosity (89% of the RC treatment) relative to values for RC. Average nodal pore volume and throat radii of buffers were 1.8 and 2.9 times larger, respectively, than for RC. Results show that three‐dimensional structural differences caused by variations in root growth or organic matter accumulation discriminated between buffer and row crop soil, allowing better quantification of management effects on soil porosity.
Effects of De‐oiled Two‐Phase Olive Mill Waste on Mediterranean Soils and the Wheat Crop
Authors: López-Piñeiro A. , Fernández J. , Albarrán A. , Nunes J. M. Rato , Barreto C.
Published: January 2008

Semiarid Mediterranean soils under intensive continuous cultivation have a net deficit of C, and addition of organic wastes is becoming a common practice as a disposal strategy and an interesting solution to redress this deficiency. A 2‐yr greenhouse study using wheat (Triticum aestivumL.) was conducted to evaluate the potential use of the final solid waste of the new technology of olive‐oil extraction (de‐oiled two‐phase olive mill waste, DTPOMW) as a soil conditioner and amendment agent. Two representative Mediterranean agricultural soils, a Typic Haploxeralf (TH) and a degraded Lithic Xerorthent (LX) were used. Treatments included five DTPOMW rates ranging from 0 to 40 Mg ha−1combined with mineral fertilizer. Significant direct and residual increases in organic C, total N, available K, cation exchange capacity, and aggregate stability were observed in both soils; however, available P decreased significantly. In the first year of the experiment, an application of 40 Mg DTPOMW ha−1had a depressive effect on grain yield and on the N and P content in the wheat grain for the LX soil, while in the TH soil there was a positive effect on yield at the same loading rate. There was an increased residual fertilization and amendment effect of DTPOMW for both soils during the second experimental year, and the grain yields increased by 23 and 202% when 40 Mg DTPOMW ha−1was applied to the TH and LX soils, respectively. For both soils, the best fits to grain yield vs. DTPOMW rates were with a quadratic regression (R2= 0.977,P< 0.001 for TH;R2= 0.983,P< 0.001 for LX). Raw DTPOMW may be a potentially valuable soil amendment agent and source of organic matter, N, and K because it maintains a positive, beneficial effect on wheat grain yield and soil properties for 24 mo following application.
Soil Carbon Saturation: Linking Concept and Measurable Carbon Pools
Authors: Stewart Catherine E. , Plante Alain F. , Paustian Keith , Conant Richard T. , Six Johan
Published: January 2008

The soil C saturation concept suggests a limit to whole soil organic carbon (SOC) accumulation determined by inherent physicochemical characteristics of four soil C pools: unprotected, physically protected, chemically protected, and biochemically protected. Previous attempts to quantify soil C sequestration capacity have focused primarily on silt and clay protection and largely ignored the effects of soil structural protection and biochemical protection. We assessed two contrasting models of SOC accumulation, one with no saturation limit (i.e., linear first‐order model) and one with an explicit soil C saturation limit (i.e., C saturation model). We isolated soil fractions corresponding to the C pools (i.e., free particulate organic matter [POM], microaggregate‐associated C, silt‐ and clay‐associated C, and nonhydrolyzable C) from eight long‐term agroecosystem experiments across the United States and Canada. Due to the composite nature of the physically protected C pool, we fractioned it into mineral‐ vs. POM‐associated C. Within each site, the number of fractions fitting the C saturation model was directly related to maximum SOC content, suggesting that a broad range in SOC content is necessary to evaluate fraction C saturation. The two sites with the greatest SOC range showed C saturation behavior in the chemically, biochemically, and some mineral‐associated fractions of the physically protected pool. The unprotected pool and the aggregate‐protected POM showed linear, nonsaturating behavior. Evidence of C saturation of chemically and biochemically protected SOC pools was observed at sites far from their theoretical C saturation level, while saturation of aggregate‐protected fractions occurred in soils closer to their C saturation level.
Estimating Regional Changes in Soil Carbon with High Spatial Resolution
Authors: West Tristram O. , Brandt Craig C. , Wilson Bradly S. , Hellwinckel Chad M. , Tyler Donald D. , Marland Gregg , De La Torre Ugarte Daniel G. , Larson James A. , Nelson Richard G.
Published: January 2008

To manage lands locally for C sequestration and for emissions reductions, it is useful to have a system that can monitor and predict changes in soil C and greenhouse gas emissions with high spatial resolution. We are developing a C accounting framework that can estimate C dynamics and net emissions associated with changes in land management. One component of this framework integrates field measurements, inventory data, and remote sensing products to estimate changes in soil C and to estimate where these changes are likely to occur at a subcounty (30‐ by 30‐m) resolution. We applied this framework component to a midwestern region of the United States that consists of 679 counties approximately centered around Iowa. We estimated the 1990 baseline soil C to a maximum depth of 3 m for this region to be 4117 Tg. Cumulative soil C accumulation of 70.3 Tg was estimated for this region between 1991 and 2000, of which 33.8 Tg is due to changes in tillage intensity. Without accounting for soil C loss following changes to more intensive tillage practices, our estimate increases to 45.0 Tg C. This difference indicates that on‐site permanence of soil C associated with a change to less intensive tillage practices is approximately 75% if no additional economic incentives are provided for soil C sequestration practices. This C accounting framework offers a method to integrate inventory and remote sensing data on an annual basis and to transparently account for alternating annual trends in land management and associated C stocks and fluxes.
Chamber Measurements of Soil Nitrous Oxide Flux: Are Absolute Values Reliable?
Authors: Rochette Philippe , Eriksen-Hamel Nikita S.
Published: January 2008

The vast majority of soil N2O flux data reported in the literature was obtained using non‐flow‐through non‐steady‐state (NFT‐NSS) chambers. Considerable variation in chamber methodology may influence N2O flux measurements, however, raising concerns about the reliability and accuracy of these measurements. The objectives of this study were to determine criteria for assessing the quality of soil N2O flux measurements made using NFT‐NSS chambers, to evaluate NFT‐NSS chamber methodologies used in the scientific literature, and to propose a minimum set of criteria for NFT‐NSS chamber design and deployment methodology. We identified 16 characteristics of chamber methodology and developed four factors contributing to the quality of N2O flux measurements made using NFT‐NSS chambers. We compiled a data set of 356 studies and evaluated the quality of each study against the set of characteristics and factors to determine the confidence in the reported N2O flux. Confidence in the absolute flux values reported in about 60% of the studies was estimated to be very low or low due to poor methodologies or incomplete reporting. The confidence in flux measurements improved with time; however, there were still about 50% of recent studies (2005–2007) with low or very low confidence levels. This study has shown that the quality of soil N2O flux measurements reported in the literature is often poor. While the flux data obtained may be valid for comparisons between situations (e.g., treatments) within a given study, they are often biased estimates of actual fluxes. We propose a minimum set of criteria for reliable soil N2O flux measurements using NFT‐NSS chambers.
Map Projections Minimizing Distance Errors
Authors: Richard Gott J. , Mugnolo Charles , Colley Wesley N.
Published: January 2008

Maps convey important information about distances between pairs of points. It is therefore desirable to minimize the errors made in representing distances between pairs of points on maps. Since it is just as bad to have two points on the map at twice their proper separation as to have them at half their proper separation, it is the root-mean-square (rms) logarithmic distance between random points in the mapped region that we will minimize. The best previously known projection of the entire sphere for distances is the Lambert equal-area azimuthal, with an rms logarithmic distance error of σ = 0.343. By way of comparison, the Mercator projection has σ = 0.444 and the Mollweide, σ = 0.390. We present three new projections – the Gott equal-area elliptical, with perfect shapes on the central meridian; the Gott-Mugnolo equal-area elliptical; and the Gott-Mugnolo azimuthal, with rms logarithmic distance errors of σ = 0.365, σ = 0.348, and σ = 0.341 respectively – that improve on previous projections of their type. The Gott-Mugnolo azimuthal projection has the lowest distance errors of any map and is produced by a new technique using “forces” between pairs of points on a map, which make the points move so as to minimize σ. The Gott equal-area elliptical projection produces a particularly attractive map of Mars, and the Gott-Mugnolo azimuthal projection produces an interesting map of the Moon, both of which we also show.
Old Dispersions and Scenes for the Production of Public Space The Constructive Margins of Secondarity
Authors: de Meulder Bruno
Published: January 2008

The density of development in Belgium is such that the entire country has become an open city, with little sense of where one metropolitan area begins and another ends. Bruno De Meulder describes the underlying logic of this unbroken urbanscape, and the opportunity it affords for re‐editing and reinserting informal social spaces in areas of wasted land. Copyright © 2008 John Wiley & Sons, Ltd.
Reinvigorating Childhood
Authors: Watson Howard
Published: January 2008

Howard Watson is uplifted by the ‘brave, graceful subtlety’ of Caruso St John's redevelopment of the Bethnal Green Museum of Childhood in east London. He finds the pared‐down spaces of the interior surprisingly in accord with the original Victorian structure, drawing their inspiration from ‘the regimented order of grand Victorian museology’. Copyright © 2008 John Wiley & Sons, Ltd.
Natural Methods of Interaction Or Natural Interaction in the Everyday Digital World
Authors: Croci Valentina
Published: January 2008

Computers, mobiles and automatised machines are so omnipresent that the means by which we interact with digital devices is now generally regarded as a given. Italian practice iO Agency, though, questions our use of mechanised interfaces and the language that they require us to learn. Valentina Croci explains how iO Agency has developed more natural ways for people to interact with digital environments through physical or tactile ‘triggers’. Copyright © 2008 John Wiley & Sons, Ltd.
On the energy transfer between the electromagnetic field and nanomachines for biological applications
Authors: Bellizzi G. , Bucci O. M. , Capozzoli A.
Published: January 2008

The article presents a simple expression of the power transferred from the electromagnetic field (EMF) to a biological nanomachine (NM) embedded in a background medium (BM). The expression is useful to analyse the interaction mechanism and test the hypothesis on its nature. Furthermore, it should represent a helpful tool to design remotely controlled NMs for bio‐medical applications and the relative electromagnetic control apparatuses. Finally, to show its practical usefulness, we used it to discuss the hypothesis on the energy transfer mechanism proposed in the literature to explain intriguing experimental phenomena referring to the remotely controlled dehybridization of DNA molecules attached to gold nanocrystals. Bioelectromagnetics 29:331–339, 2008. © 2008 Wiley‐Liss, Inc.
Improvement of student understanding of how kinetic data facilitates the determination of amino acid catalytic function through an alkaline phosphatase structure/mechanism bioinformatics exercise
Authors: Grunwald Sandra K. , Krueger Katherine J.
Published: January 2008

Laboratory exercises, which utilize alkaline phosphatase as a model enzyme, have been developed and used extensively in undergraduate biochemistry courses to illustrate enzyme steady‐state kinetics. A bioinformatics laboratory exercise for the biochemistry laboratory, which complements the traditional alkaline phosphatase kinetics exercise, was developed and implemented. In this exercise, students examine the structure of alkaline phosphatase using the free, on‐line bioinformatics protein‐modeling program Protein Explorer. Specifically, students examine the active site residues of alkaline phosphatase and propose functions for these residues. Furthermore, by examining the mechanism of alkaline phosphatase and by using the published kinetic data, students propose specific roles for several active‐site residues. Paired t‐test analysis of pre‐ versus postexercise assessment data shows that the completion of the exercise improves student's ability to use kinetic data correctly thereby determining a probable catalytic function for an active site amino acid.
Interactive computer simulations of genetics, biochemistry, and molecular biology
Authors: White Brian T. , Bolker Ethan D.
Published: January 2008

This article describes three interactive software simulations targeted to key domains of modern molecular genetics: genetics, biochemistry, and molecular biology. These simulations allow students to deepen their understanding of key principles in these domains by setting up crosses, designing proteins, and designing genes; the simulations then apply these principles to produce results that the students can interpret. Using this software, students can confront their misconceptions and connect these disciplines in a way that is difficult if not impossible without an interactive environment. We present lab exercises that guide the students as they use the software in a series of activities that begin by introducing the tools and build towards more open inquiry. Preliminary evaluation shows that students enjoy the software and that it promotes active engagement and application of the material. The open‐source Java software and the relevant lab manuals are available free of charge on line.
Diffuse interface method for simulation of the chemical vapor deposition of pyrolytic carbon: Aspects of the mathematical formulation
Authors: Dimitrov S. , Ekhlakov A. , Langhoff T.‐A.
Published: January 2008

The present work is inspired by Anderson et al. (Phys. D Nonlinear Phenom. 2000; 135(1–2):175–194) and Noll (http://www.math.cmu.edu/wn0g/noll) and falls in the conceptual line of the Ginzburg–Landau class of first‐order phase‐transition models based on the concept of phase‐field parameter. Trying to keep the exposition as much general as possible, we develop below a thermodynamically consistent rationalization of the physical process of (anisotropic) deposition of pyrolytic carbon from a gas phase. The derivation line we follow is well established in the field of the modern continuum physics. From the covariance of the first principle of thermodynamics, the second Newton's law and the Liouville's theorem with respect to the one‐dimensional Lie groups of transformations, the balance laws for the temperature, linear momentum and density are formulated. This system of partial differential equations is comprehended further by the constitutive laws for the phase field, the stress, and the heat and entropy fluxes obtained in a form consistent with the Clausius–Duhem understanding of the second law. The result referred to as a local, strongly coupled initial boundary value problem of chemical vapor deposition (IBVP‐CVD) constitutes the general mathematical description of the CVD process. The weak form of isotropic IBVP‐CVD is then derived and discretized by means of the discontinuous Galerkin method. At the end of the paper, we also derive the weak formulations for the local lifting operators that provide the stabilization mechanism for the discontinuous Galerkin discretization scheme. Copyright © 2008 John Wiley & Sons, Ltd.
Dynamic numerical simulations of void growth and coalescence with stress triaxiality maintained constant—Application to ductile solids with secondary voids
Authors: Siad L.
Published: January 2008

Dynamic explicit finite element analysis is used to investigate void growth and plastic collapse of an axisymmetric unit cell model with a primary spherical void imbedded in a porous matrix material. The Gurson–Tvergaard–Needleman homogenized model is used to describe the plastic behaviour of the matrix material. The simulations are performed under large strain conditions for varying secondary void volume fractions and quasi‐static loading controlled by constant stress triaxiality. The proposed accomplishment of constant stress triaxiality associated with dynamic explicit computations provides a method allowing to trace the collapse of the unit cell from the onset of coalescence to practically its final failure. Consistent with experimental and theoretical results available in the literature, the obtained results substantiate the sensitivity of coalescence to the presence of secondary voids. Copyright © 2008 John Wiley & Sons, Ltd.
Forecasting value‐at‐risk with a parsimonious portfolio spillover GARCH (PS‐GARCH) model
Authors: Mcaleer Michael , da Veiga Bernardo
Published: January 2008

Accurate modelling of volatility (or risk) is important in finance, particularly as it relates to the modelling and forecasting of value‐at‐risk (VaR) thresholds. As financial applications typically deal with a portfolio of assets and risk, there are several multivariate GARCH models which specify the risk of one asset as depending on its own past as well as the past behaviour of other assets. Multivariate effects, whereby the risk of a given asset depends on the previous risk of any other asset, are termed spillover effects. In this paper we analyse the importance of considering spillover effects when forecasting financial volatility. The forecasting performance of the VARMA‐GARCH model of Ling and McAleer (2003), which includes spillover effects from all assets, the CCC model of Bollerslev (1990), which includes no spillovers, and a new Portfolio Spillover GARCH (PS‐GARCH) model, which accommodates aggregate spillovers parsimoniously and hence avoids the so‐called curse of dimensionality, are compared using a VaR example for a portfolio containing four international stock market indices. The empirical results suggest that spillover effects are statistically significant. However, the VaR threshold forecasts are generally found to be insensitive to the inclusion of spillover effects in any of the multivariate models considered.  Copyright © 2008 John Wiley & Sons, Ltd.
High molecular weight adiponectin inhibits proliferation of hepatic stellate cells via activation of adenosine monophosphate–activated protein kinase
Authors: Adachi Masayuki , Brenner David A.
Published: January 2008

Adiponectin is an adipocyte-derived, antidiabetic, antiatherogenic adipocytokine that is present in serum as 3 isoforms. Decreased plasma adiponectin levels are closely associated with the severity of nonalcoholic fatty liver diseases. This study was designed to elucidate a role of adiponectin and its mediator adenosine monophosphate–activated protein kinase (AMPK) on proliferation of activated hepatic stellate cells (HSCs), the key cells promoting fibrosis. Immortalized human HSC line hTERT and primary rat HSCs were stimulated with platelet-derived growth factor (PDGF) with or without pretreatment with AMPK activator 5-aminoimidazole-4-carboxamide-1-4-ribofuranoside (AICAR), metformin, or high molecular weight (HMW) adiponectin. HMW adiponectin dose-dependently suppressed PDGF-induced HSC proliferation. Adenoviral transduction with dominant-negative AMPK (DN-AMPK) abolished the suppressive effect of adiponectin in HSCs. AICAR, metformin, or transduction of constitutively active AMPK attenuated PDGF-induced [3H]thymidine incorporation, which was abolished by either a chemical AMPK inhibitor or transduction of DN-AMPK, consistent with an antiproliferative effect of AMPK. The suppressive effect of AMPK on HSC proliferation is mediated through multiple mechanisms, including (1) an inhibition of the AKT pathway, (2) inhibition of NADPH oxidase–dependent reactive oxygen species (ROS) production via induction of antioxidant enzymes, and (3) an increase in the expression of the cyclin-dependent kinase inhibitors p27kip1 and p21cip1.

Conclusion:

Adiponectin inhibits HSC proliferation via activation of AMPK. AMPK activation by AICAR or metformin inhibits HSC proliferation via suppression of ROS production and subsequent inhibition of AKT pathway. Thus, adiponectin and AMPK inhibit HSC proliferation and hepatic fibrosis via multiple molecular mechanisms. (Hepatology 2008;47:677–685.)
Hepatic parenchymal replacement in mice by transplanted allogeneic hepatocytes is facilitated by bone marrow transplantation and mediated by CD4 cells
Authors: Streetz Konrad L. , Doyonnas Regis , Grimm Dirk , Jenkins Denison D. , Fuess Sally , Perryman Scott , Lin Joseph , Trautwein Christian , Shizuru Judith , Blau Helen , Sylvester Karl G. , Kay Mark A.
Published: January 2008

The lack of adequate donor organs is a major limitation to the successful widespread use of liver transplantation for numerous human hepatic diseases. A desirable alternative therapeutic option is hepatocyte transplantation (HT), but this approach is similarly restricted by a shortage of donor cells and by immunological barriers. Therefore,

in vivo

expansion of tolerized transplanted cells is emerging as a novel and clinically relevant potential alternative cellular therapy. Toward this aim, in the present study we established a new mouse model that combines HT with prior bone marrow transplantation (BMT). Donor hepatocytes were derived from human alpha(1)-antitrypsin (hAAT) transgenic mice of the FVB strain. Serial serum enzyme-linked immunosorbent assays for hAAT protein were used to monitor hepatocyte engraftment and expansion. In control recipient mice lacking BMT, we observed long-term yet modest hepatocyte engraftment. In contrast, animals undergoing additional syngeneic BMT prior to HT showed a 3- to 5-fold increase in serum hAAT levels after 24 weeks. Moreover, complete liver repopulation was observed in hepatocyte-transplanted Balb/C mice that had been transplanted with allogeneic FVB-derived bone marrow. These findings were validated by a comparison of hAAT levels between donor and recipient mice and by hAAT-specific immunostaining. Taken together, these findings suggest a synergistic effect of BMT on transplanted hepatocytes for expansion and tolerance induction. Livers of repopulated animals displayed substantial mononuclear infiltrates, consisting predominantly of CD4(+) cells. Blocking the latter prior to HT abrogated proliferation of transplanted hepatocytes, and this implied an essential role played by CD4(+) cells for

in vivo

hepatocyte selection following allogeneic BMT.

Conclusion:

The present mouse model provides a versatile platform for investigation of the mechanisms governing HT with direct relevance to the development of clinical strategies for the treatment of human hepatic failure. (Hepatology 2008;47:706–718.)
Low circulating levels of dehydroepiandrosterone in histologically advanced nonalcoholic fatty liver disease
Authors: Charlton Michael , Angulo Paul , Chalasani Naga , Merriman Ralph , Viker Kimberly , Charatcharoenwitthaya Phunchai , Sanderson Schuyler , Gawrieh Samer , Krishnan Anuradha , Lindor Keith
Published: January 2008

The biological basis of variability in histological progression of nonalcoholic fatty liver disease (NAFLD) is unknown. Dehydroepiandrosterone (DHEA) is the most abundant steroid hormone and has been shown to influence sensitivity to oxidative stress, insulin sensitivity, and expression of peroxisome proliferator-activated receptor alpha and procollagen messenger RNA. Our aim was to determine whether more histologically advanced NAFLD is associated with low circulating levels of DHEA. Serum samples were obtained prospectively at the time of liver biopsy in 439 patients with NAFLD (78 in an initial and 361 in validation cohorts) and in controls with cholestatic liver disease (n = 44). NAFLD was characterized as mild [simple steatosis or nonalcoholic steatohepatitis (NASH) with fibrosis stage 0-2] or advanced (NASH with fibrosis stage 3-4). Serum levels of sulfated DHEA (DHEA-S) were measured by enzyme-linked immunosorbent assay. Patients with advanced NAFLD had lower plasma levels of DHEA-S than patients with mild NAFLD in both the initial (0.25 ± 0.07 versus 1.1 ± 0.09 μg/mL,

P

< 0.001) and validation cohorts (0.47 ± 0.06 versus 0.99 ± 0.04 μg/mL,

P

< 0.001). A “dose effect” of decreasing DHEA-S and incremental fibrosis stage was observed with a mean DHEA-S of 1.03 ± 0.05, 0.96 ± 0.07, 0.83 ± 0.11, 0.66 ± 0.11, and 0.35 ± 0.06 μg/mL for fibrosis stages 0, 1, 2, 3, and 4, respectively. All patients in both cohorts in the advanced NAFLD group had low DHEA-S levels, with the majority in the hypoadrenal range. The association between DHEA-S and severity of NAFLD persisted after adjusting for age. A relationship between disease/fibrosis severity and DHEA-S levels was not seen in patients with cholestatic liver diseases.

Conclusion:

More advanced NAFLD, as indicated by the presence of NASH with advanced fibrosis stage, is strongly associated with low circulating DHEA-S. These data provide novel evidence for relative DHEA-S deficiency in patients with histologically advanced NASH. (Hepatology 2008;47:484–492.)
HBeAg and hepatitis B virus DNA as outcome predictors during therapy with peginterferon alfa-2a for HBeAg-positive chronic hepatitis B
Authors: Fried Michael W. , Piratvisuth Teerha , Lau George K. K. , Marcellin Patrick , Chow Wan-Cheng , Cooksley Graham , Luo Kang-Xian , Paik Seung Woon , Liaw Yun-Fan , Button Peter , Popescu Matei
Published: January 2008

The aims of this study were to evaluate the usefulness of quantitative hepatitis B e antigen (HBeAg) values for predicting HBeAg seroconversion in patients treated with peginterferon alfa-2a and to assess the dynamic changes in quantitative HBeAg during therapy, compared with conventional measures of serum hepatitis B virus DNA. Data were analyzed from a large, randomized, multinational phase III registration trial involving 271 HBV-infected HBeAg-positive patients who received peginterferon alfa-2a plus oral placebo for 48 weeks. HBeAg levels were measured serially during therapy using a microparticle enzyme immunoassay validated with in-house reference standards obtained from the Paul Ehrlich Institute (PEIU/mL). In patients who achieved HBeAg seroconversion, levels of HBeAg consistently decreased during treatment and remained at their lowest level during the 24 weeks of posttreatment follow-up. After 24 weeks of treatment, 4% of patients with the highest levels of HBeAg (≥100 PEIU/mL) achieved HBeAg seroconversion, yielding a negative predictive value of 96%, which was greater than that obtained for levels of HBV DNA (86%). Late responders to peginterferon alfa-2a could also be differentiated from nonresponders by continued decrease in HBeAg values, which were not evident by changes in HBV DNA.

Conclusion:

These analyses suggest quantitative HBeAg is a useful adjunctive measurement for predicting HBeAg seroconversion in patients treated with peginterferon when considering both sensitivity and specificity compared with serum HBV DNA. (Hepatology 2008;47:428–434.)
Rheological properties of immiscible polymer blends under parallel superposition shear flow
Authors: Chen Quan , Yu Wei , Zhou Chixing
Published: January 2008

The small amplitude oscillations can be superimposed parallelly on steady shear flows. The resulting moduli provide information about time‐ and shear‐dependent microstructure. For this purpose, model blends composed of polydimethylsiloxane and polyisobutylene with the viscosity ratio of 7.9 and 0.25 are investigated. The resulting moduli are compared with the results derived from numerical calculation as well as analytical solutions, developed here by introducing the conditions under parallel superposition flow field into MM model. Good agreement is found in the interfacial contribution of the storage moduli for blend with low volume fraction. Moreover, detailed analysis on hydrodynamic interaction between droplets is given to explain the discrepancies. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 431–440, 2008
Skin‐Sparing Mastectomy with Immediate Breast Reconstruction by a New Modification of Extended Latissimus Dorsi Myocutaneous Flap
Authors: Denewer Adel , Setit Ahmed , Hussein Osama , Farouk Omar
Published: January 2008

Background

The introduction of skin‐sparing mastectomy has revolutionized both breast cancer surgery and breast reconstruction. Latissimus dorsi myocutaneous flap is a versatile flap that is gaining renewed popularity with the development of flap modifications and the continued recognition of its reliability and safety. We report our results with a new modification of the extended latissimus dorsi flap after skin‐sparing mastectomy for breast cancer.

Methods

From January 2002 to January 2006, 140 patients of breast carcinoma had unilateral skin‐sparing mastectomy and immediate breast reconstruction. A total of 132 cases of invasive duct carcinoma and eight cases of invasive lobular carcinoma are included. Age ranged from 27 to 53 (median, 40.5) years. Tumor stage was stage I in 22 cases, stage II in 100 cases, and stage III in 18 cases. We performed a new modification to the standard extended latissimus dorsi flap, which allowed us to obtain enough autologous tissue to reconstruct the relatively large breast of the Egyptian women without implant. The postoperative aesthetic results and donor side morbidity, including contour deformity and scaring, were examined.

Results

We applied both an objective and subjective aesthetic result monitoring. Aesthetic grading results of breast reconstruction were excellent in 85, good in 42, fair in ten and poor in three cases. Both flap and donor site complications were minor. Patients were followed for a median of 32.4 (range, 12‐48) months. During this period of follow‐up, no episode of local or distant failure was observed.

Conclusions

Skin‐sparing mastectomy with immediate breast reconstruction using our new modification of extended latissimus dorsi flap allows single‐stage, totally autologous reconstruction with satisfactory aesthetic results and low morbidity.
Supplying Russia during the Great War, 1914–1918
Authors: Savours Ann
Published: January 2008

Reading Captain Richard Woodman's lament on the lack of an appropriate campaign medal for those serving in British ships involved in the transport of supplies to north Russia from 1941 to 1945 (Woodman 2007), I was reminded of their predecessors in the Great War of 1914 to 1918, when the timber port of Archangel, towards the mouth of the Dvina, together with Vladivostok, were Imperial Russia's only outlets to the sea. Captain R.F. Scott's auxiliary barque Discovery was one of a number of ships chartered to the French Government by the Hudson's Bay Company to carry matériel from Brest to the White Sea, in peril not only of tempestuous seas, but of ice and the 285 mines laid in that sea by the German auxiliary cruiser Meteor, in June 1915.
Greenland's new legislation on commercial and research-related use of biological resources: implications for the International Polar Year and later
Authors: Leary David
Published: January 2008

New possibilities for economic development have been identified by the Greenland Home Rule Government in recent years. One of these is the potential for development of biotechnology based on Greenland's biodiversity. To ensure that Greenland shares in benefits derived from the exploitation of these resources the Home Rule Parliament recently enacted legislation on commercial and research-related use of biological resources that is premised on rights recognised by the 1992 Convention on Biological Diversity. This legislation represents the first law in an Arctic jurisdiction specifically to create a mechanism for access and benefit sharing in relation to Arctic genetic resources. The main area of research and commercial interest so far relates to potential developments in biotechnology from the microbial diversity of ikaite tufa columns located in the Ikka Fjord in southwest Greenland. The legislation seeks to provide a mechanism for regulating access to such biological resources and a means for Greenland to share in the potential benefits that may come from scientific research on them and subsequent commercialisation. Much research in Greenland now falls within the scope of this legislation. The purpose of this article is to explain the provisions of the legislation to the polar research community as well as to review its implications for research in the International Polar Year and later. The legislation imposes many new obligations on researchers in Greenland including obligations to obtain survey licences, obligations on reporting and the regulation of publication of scientific research. Commercially focussed research is also tightly regulated with a particular emphasis on patent rights. However, many aspects of the legislation are uncertain and it is unclear how much of the legislation will be implemented in practice.
Role of convection triggers in the simulation of the diurnal cycle of precipitation over the United States Great Plains in a general circulation model
Authors: Lee Myong‐In , Schubert Siegfried D. , Suarez Max J. , Schemm Jae‐Kyung E. , Pan Hua‐Lu , Han Jongil , Yoo Soo‐Hyun
Published: January 2008

Recent comparisons of a number of general circulation models (GCMs) have shown that most of them have deficiencies in the simulation of the diurnal cycle of warm season precipitation. The deficiencies are particularly pronounced over the United States Great Plains where the models generally fail to capture the nocturnal rainfall maximum found in the observations. By using the National Centers for Environmental Prediction's Global Forecasting System (NCEP GFS) GCM, which is unusual in that it produces a realistic nocturnal rainfall signal over the Great Plains, this study examines the nature and realism of the mechanisms responsible for the nocturnal rain in the GCM. A series of sensitivity experiments highlight the importance of triggers implemented in the convection scheme. Specifically, the convection trigger function that the cloud base (defined as the level of free convection) must be within 150 hPa depth from the convection starting level (which crudely represents an upper limit of convective inhibition) plays a key role on the realistic simulation of the diurnal phase of convection. On the basis of this trigger, the nighttime elevation of the convection starting level (defined as the maximum level of moist static energy from the surface) above the boundary layer inversion provides the condition favorable for the development of nocturnal precipitation over the Great Plains. The results are discussed in terms of their implications for improving our understanding and parameterizations of the physical processes that generate nocturnal rain in this and other regions with large diurnal cycles.
1000
nm
tunable acousto-optic filter based on photonic crystal fiber
Authors: Hong K. S. , Park H. C. , Kim B. Y. , Hwang I. K. , Jin W. , Ju J. , Yeom D. I.
Published: January 2008

We report an all-fiber acousto-optic tunable filter based on a two-mode photonic crystal fiber. The properties of photonic crystal fiber allow us to demonstrate a notch filter tunable from below 700to1700nm with a single acoustic transducer. The extreme dynamic range coupled with small insertion loss and fast response time (∼100μs) makes this device promising for ultrawideband optical systems.
Photoluminescence of near-lattice-matched GaN∕AlInN quantum wells grown on free-standing GaN and on sapphire substrates
Authors: Tan L. T. , Martin R. W. , O’Donnell K. P. , Watson I. M. , Wu Z. H. , Ponce F. A.
Published: January 2008

Near-lattice-matched GaN∕Al1−xInxN single quantum wells, grown using both free-standing GaN and conventional GaN-on-sapphire substrates, are studied by photoluminescence (PL) and PL excitation spectroscopies. PL spectra distinguish luminescence originating in the wells, barriers, and underlying GaN buffer layers. The spectra also reveal significant differences between structures grown simultaneously on the different substrates. The quantum well transition energy decreases as the well width increases due to the intense in-built electric fields, estimated to be 3.0±0.5MeV∕cm, that persist in strain free GaN∕Al1−xInxN. Screening of these fields is studied using the excitation power dependence of the PL.
Design and fabrication of a line-defect bend sandwiched with air trenches in a photonic crystal platform
Authors: Tao S. H. , Yu M. B. , Song J. F. , Fang Q. , Yang R. , Lo G. Q. , Kwong D. L.
Published: January 2008

A hybrid bend is designed and fabricated on the silicon-on-insulator system. The hybrid bend comprises a line-defect 120° bend sandwiched by double air trenches in a photonic crystal platform. The simulation and experimental results show that the hybrid bend has low insertion loss and large high-transmission bandwidth.
Step bunch assisted two dimensional ordering of In0.19Ga0.81As∕GaAs quantum dots on vicinal GaAs(001) surfaces
Authors: Hanke M. , Wang Zh. M. , Mazur Yu. I. , Lee J. H. , Salamo G. J. , Schmidbauer M.
Published: January 2008

We have investigated the self-organized, step bunch assisted formation of In0.19Ga0.81As∕GaAs quantum dots in vertical superlattices consisting of one, four, eight, and ten periods. Samples were grown by molecular beam epitaxy on vicinal 2°A and 2°B GaAs(001) substrates. Those with miscut along the [11¯0] (2°B) exclusively show step bunches of an aspect ratio larger than 10 but without the formation of quantum dots. This highly linear pattern is improved during subsequent periods as proved by high resolution x-ray diffraction and grazing incidence diffraction. On the other hand, a miscut along the [110] (2°A) initially causes a crosslike pattern of step bunches, which finally becomes a two-dimensional arrangement of individual quantum dots.
100 PROTEOME OF BULL SPERMATOZOA
Authors: Feugang J. M. , Rozanas C. , Kaya A. , Topper E. , Memili E.
Published: January 2008

The reproductive performance of a herd is the biggest factor affecting production and product quality of livestock. Thus, a decline of male fertility represents a dramatic economic loss in beef and dairy industries. Caused by molecular defects in the spermatozoa, uncompensatory infertility is a current challenge for the cattle industry, because even with normal sperm morphology, motility, and number, fertility of bulls is still sub-par. Thus, the objective of this study was to determine the global proteome of spermatozoa collected from bulls with different fertility and study the proteins playing a role in uncompensatory infertility. We performed difference gel electrophoresis (2D-DIGE) using cryopreserved sperm from a total of 6 bulls. Spermatozoa were thawed, purified by percoll gradient, and washed in PBS solution. For each bull, a pellet of 100 million sperm cells was resuspended in the 2D-DIGE labeling buffer, and the total protein was quantified. Cell lysates were separately labeled with CyDye DIGE Fluor dyes (and reciprocally with different dyes) and multiplexed in pairs on 3 gels. The samples were focused according to their isoelectric point through an Immobiline DryStrip, pH4-7, using a IPGphor 2, followed by separation on 12.5% sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels (21.5–200 kDa) using a DALTsix. The resulting gels were scanned, and their topographic digital maps were used for algorithmic spot matching, background normalization, spot differences quantification, and elimination of artifacts (DeCyder 2-D Differential Analysis Software, GE Healthcare Life Sciences, Piscataway, NJ, USA). The results showed between 2600 and 2800 proteins with high confidence. Compared to the high-fertile bulls, 30 proteins were increased, and 27 were decreased in the low-fertility bulls within a 2-fold range. The largest significant increase and decrease were 3.97- and 2.4-fold, respectively. The identification of these differentially represented proteins is in progress. However, our results provided a panoramic view of sperm proteome from bulls of different fertility and thus paved the way for research on mechanisms of uncompensatory bull infertility.
101 PLACENTAL DEVELOPMENT IN A BOVINE HETEROSIS MODEL
Authors: Fitzsimmons C. , Kruk Z. , Lines D. , Roberts C. , Hiendleder S.
Published: January 2008

Heterosis or hybrid vigor is a biological phenomenon referring to the phenotypic superiority of hybrids over their parents. Despite its economic importance, the mechanisms of heterosis are still poorly understood. Reciprocal cross Brahman (B) � Angus (A) calves display significant heterosis in birth weight, but this effect is almost entirely due to the dramatic fetal overgrowth observed in Brahman male � Angus female offspring. The reciprocal is much less affected and similar to purebred Brahman calves (Brown et al. 1993 J. Anim. Sci. 71, 3273–3279). We have generated a defined A � A (n = 20), B � A (n = 21), A � B (n = 13), and B � B (n = 15; male parent listed first) day 153 (term = 280) fetal/placental resource from artificially inseminated, estrous cycle synchronized heifers to identify components and mechanisms of heterotic fetal growth regulation. An ANOVA showed that full uterus weight (P < 0.001), fetal weight (P = 0.01), umbilical cord length (P = 0.003) and weight (P = 0.04), placenta fetalis weight (P < 0.001), total caruncle weight (P = 0.002), empty uterus weight (P < 0.001), and combined amniotic/allantoic fluid weight (P < 0.001) were significantly affected by the 4 genetic groups after adjustment for fetal sex and dam weight where required. The weight of reciprocal hybrid fetuses was intermediate to the purebred fetuses and thus did not display heterosis defined as the difference between reciprocal cross and parental means. Full uterus weight and combined amniotic/allantoic fluid weight, in contrast, displayed heterosis of 6.6% (P = 0.02) and 9.0% (P = 0.01). As in neonate calves, the heterosis effects were due to the B � A group. The t-tests demonstrated that full uterus weight in B � A was significantly greater (19.84 � 0.43 kg) than in A � B (16.23 � 0.47 kg; P < 0.001), A � A (17.41 � 0.35 kg; P < 0.001), and B � B (16.76 � 0.49 kg; P = 0.001) crosses. Combined amniotic/allantoic fluids were 12.58 � 0.31 kg in B � A as compared to 10.93 � 0.39 kg in A � B (P = 0.001), 10.75 � 0.29 kg in A � A (P < 0.001), and 11.48 � 0.36 kg in B � B (P = 0.02) crosses. We found similar superiority of the B � A group for parameters that did not fulfil the formal heterosis criterion. These include umbilical cord, placenta fetalis, empty uterus, and total caruncle weights. All but 1 of these (combined amniotic/allantoic fluid weight) were significantly correlated (r = 0.43–0.70; P < 0.001) with fetal weight. We conclude that massive changes in placental parameters underly and precede the heterosis effects in birth weight observed in Brahman � Angus crosses. Although formally designated heterosis, placental and fetal overgrowth is present in only 1 of the hybrids (B � A). This natural overgrowth phenotype is clearly distinct from the early onset overgrowth phenotypes observed after IVF and nuclear transfer cloning (Hiendleder et al. 2004 Biol. Reprod. 71, 217–223) and will be useful in the dissection of factors contributing to fetal growth and development.