bluuebunny/crossref_metadata_2025_split huggingface dataset:
Negative refraction of low‐frequency electromagnetic waves
Authors: Tarkhanyan Roland H. , Niarchos Dimitris G. 
Published: August 2008

AbstractFeatures of anomalous refraction of low‐frequency electromagnetic waves are investigated in all‐semiconductor nonmagnetic superlattices with a periodic array of two‐dimensional electron gas layers under quantum Hall effect conditions. We show that the structure exhibits negative refraction on the lateral surface for all angles of incidence, in the frequency region which has no limitation from the low‐frequency side, and that for such intriguing properties it requires no resonance frequency and no negative component of the permittivity tensor. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of the oxygen and hydrogen isotopes in the juices of fast‐growing vegetables and slow‐growing fruits
Authors: Bong Yeon‐Sik , Lee Kwang‐Sik , Shin Woo‐Jin , Ryu Jong‐Sik 
Published: August 2008

AbstractWe have analyzed the oxygen and hydrogen isotopic composition of juices from fruits and vegetables collected from a small orchard in order to investigate the differences in isotopic enrichment and evaporation intensity between fast‐growing vegetables and slow‐growing fruits grown under the same climatic conditions. The oxygen and hydrogen isotope levels were much higher in the juices of the fruits and vegetables than in the source waters in which they grew because of evaporation effects. According to our data, fast‐growing vegetables are subject to greater evaporation than slow‐growing fruits. An evaporation experiment using the source water showed that the oxygen and hydrogen isotopic composition of the 60–80% residual fraction was similar to that of the isotopically enriched grape juice, whereas those of the plume and tomato juices were very close to that of the 80–90% residual fraction, thus proving the effect of evaporation. Copyright © 2008 John Wiley & Sons, Ltd.
Identification and characterization of active compounds and their metabolites by high‐performance liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry after oral administration of a herbal extract of Epimedium koreanum Nakai to rats
Authors: Wu Caisheng , Sheng Yuxin , Zhang Yinghao , Zhang Jinlan , Guo Baolin 
Published: August 2008

AbstractEpimedium is an important traditional Chinese medicine that is widely used throughout China as a tonic, aphrodisiac, and antirheumatic medicine. Flavonoids are considered to be the active compounds in Epimedium. In the study reported here, high‐performance liquid chromatography coupled with Fourier transform‐ion cyclotron resonance mass spectrometry (HPLC/FTICR‐MS) was developed to identify active compounds and their metabolites after oral administration of a herbal extract of Epimedium koreanum Nakai to rats, using parent mass list triggered data‐dependent multiple‐stage accurate mass analysis at a resolving power of 100 000 in the external calibration mode. Nine flavonoids were identified in rats. The chemical formulae with unsaturation numbers calculated from accurate m/z values of precursor and product ions were used to assign the structures of metabolites and the chemical sites of metabolism. The mass accuracies obtained for all full‐scan MS and MSn spectra were within 3 ppm (<1 ppm in most cases). The majority of the metabolites identified have been previously reported, but three compounds were noted for the first time in rats. By contrasting the analytical results obtained from the herbal extract with those obtained from biological specimens, the profile of flavonoid biotransformation in Epimedium was obtained and the metabolic pathways of these components, in rats, are described. The results should be of use in targeting potential active ingredients in Epimedium. Copyright © 2008 John Wiley & Sons, Ltd.
Rapid screening method for intact glucosinolates in Chinese medicinal herbs by using liquid chromatography coupled with electrospray ionization ion trap mass spectrometry in negative ion mode
Authors: Lee Kim‐Chung , Chan Wan , Liang Zhitao , Liu Ning , Zhao Zhongzhen , Lee Albert Wai‐Ming , Cai Zongwei 
Published: August 2008

AbstractAn optimized method using liquid chromatography coupled with electrospray ionization ion trap mass spectrometry (LC/ESI‐ITMS) in negative ion mode has been developed for screening different structural classes of intact glucosinolates in six Chinese medicinal herbs. The glucosinolates were extracted with hot methanol/water (70:30 v/v) and separation of the individual glucosinolates was achieved using a reversed‐phase C18 column with an aqueous ammonium acetate/methanol gradient. Identification of the intact glucosinolates was based on the detection of compounds with a constant neutral loss of 242 Da corresponding to the combined loss of anhydroglucose (162 Da) and sulfur trioxide (80 Da) in collision‐induced dissociation. The structures of the identified glucosinolates were confirmed with the use of group‐specific product ions at m/z 195, 241, 259, 275 in their corresponding MS/MS product ion spectra. Differentiation of intact glucosinolates was achieved through their respective retention times and molecular masses as well as the characteristic product ions. The limits of detection were at the low nanogram level per injection, based on constant neutral loss scans. Significant variation in the compositions of intact glucosinolates was identified in the cruciferous herbs. This method was applied in the differentiation and quality control of two pairs of easily confused herbs. Copyright © 2008 John Wiley & Sons, Ltd.
Mangrove trees growing in a very saline condition but not using seawater
Authors: Lambs Luc , Muller Etienne , Fromard Francois 
Published: August 2008

AbstractMangrove trees, which develop along tropical coasts, are known to use saline water uptake. In French Guiana, the high salinity condition is the result of seawater evaporation on mud banks formed from the Amazon sediment flumes. In the back mangrove a few kilometres inland, groundwater, soil water and the xylem sap uptake in the trees remain highly salty, and only very tolerant plants like Avicennia germinans can flourish, whereas the less salt‐tolerant Rhizophora mangle is more difficult to find. Curiously, the same Avicennia trees propagate on the seafront. However, stable isotope ratio mass spectrometry (IRMS) measurements and ion analysis (high‐performance liquid chromatography (HPLC) and inductively coupled plasma atomic emission (ICP‐AES) spectroscopy reveal that the origin of the water in the back mangrove is not seawater. It is freshwater percolating into the sand bars from the inland marshes and rainwater during the wet season that redissolves a marine evaporite and gives a saline groundwater. The absence of barren saltine areas (‘tanne’) in French Guiana could be explained by this freshwater inflow, the aquifer being no longer linked with the ocean. Copyright © 2008 John Wiley & Sons, Ltd.
Selected ion flow tube mass spectrometry of exhaled breath condensate headspace
Authors: Čáp Petr , Dryahina Kseniya , Pehal František , Španěl Patrik 
Published: August 2008

AbstractCollection of exhaled breath condensate (EBC) is a relatively simple noninvasive method of breath analysis; however, no data have been reported that would relate concentration of volatile compounds in EBC to their gaseous concentrations in exhaled air. The aim of the study was to investigate which volatile compounds are present in EBC and how their concentrations relate to results of direct breath analysis. Thus, samples of EBC were collected in a standard way from several subjects and absolute levels of several common volatile breath metabolites (ammonia, acetone, ethanol, methanol, propanol, isoprene, hydrogen cyanide, formaldehyde and acetaldehyde) were then determined in their headspace using selected ion flow tube mass spectrometry (SIFT‐MS). Results are compared with those from on‐line breath analyses carried out immediately before collecting the EBC samples. It has been demonstrated that SIFT‐MS can be used to quantify the concentrations of volatiles in EBC samples and that, for methanol, ammonia, ethanol and acetone, the EBC concentrations correlate with the direct breath levels. However, the EBC concentrations of isoprene, formaldehyde, acetaldehyde, hydrogen cyanide and propanol do not correlate with direct breath measurements. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluation of a method for fitting a semi‐Markov process model in the presence of left‐censored spells using the Cardiovascular Health Study
Authors: Cai Liming , Schenker Nathaniel , Lubitz James , Diehr Paula , Arnold Alice , Fried Linda P. 
Published: August 2008

AbstractWe used a longitudinal data set covering 13 years from the Cardiovascular Health Study to evaluate the properties of a recently developed approach to deal with left censoring that fits a semi‐Markov process (SMP) model by using an analog to the stochastic EM algorithm—the SMP‐EM approach. It appears that the SMP‐EM approach gives estimates of duration‐dependent probabilities of health changes similar to those obtained by using SMP models that have the advantage of actual duration data. SMP‐EM estimates of duration‐dependent transition probabilities also appear more accurate and less variable than multi‐state life table estimates. Published in 2008 by John Wiley & Sons, Ltd.
Regaining power lost by non‐compliance via full probability modelling
Authors: Becque T. , White I. R. 
Published: August 2008

AbstractNon‐compliance, or non‐receipt of randomized intervention, is a common problem in randomized controlled trials. An intention‐to‐treat (ITT) analysis, which compares individuals as randomized, under‐estimates the efficacy of the intervention and leads to a loss of power. We explore the possibility of regaining some of this power in a setting with all‐or‐nothing compliance, without making any assumptions about the comparability of compliers and non‐compliers. Efficacy may be specified as the complier average causal effect (CACE), which is the difference in mean outcome among compliers. Compliance is only partially observed, but under an exclusion restriction assumption, the CACE may be estimated using maximum likelihood. In order to quantify the possible gain in power, we derive an expression for the asymptotic relative efficiency (ARE) of the CACE relative to the ITT effect with a Normally distributed outcome. Under the assumption of a common CACE across covariate strata, the CACE estimate is at least as powerful as ITT analysis. The inclusion of covariates that predict compliance enables an additional gain in power, which is investigated algebraically. Using data from three clinical trials, we obtain values of the ARE ranging up to 1.05 due to covariates alone, and 1.13 due to CACE modelling alone, corresponding to gains in power of up to 5 per cent. This implies that a large gain in power obtained using as‐treated or per‐protocol analyses is likely to be due to the strong and often implausible assumptions such analyses require to be valid. Copyright © 2008 John Wiley & Sons, Ltd.
Testing linkage disequilibrium from pooled DNA: A contingency table perspective
Authors: Xu Jinfeng , Yang Yaning , Ying Zhiliang , Ott Jurg 
Published: August 2008

AbstractPooling DNA samples of multiple individuals has been advocated as a method to reduce genotyping costs. Under such a scheme, only the allele counts at each locus, not the haplotype information, are observed. We develop a systematic way for handling such data by formulating the problem in terms of contingency tables, where pooled allele counts are expressed as the margins and the haplotype counts correspond to the unobserved cell counts. We show that the cell frequencies can be uniquely determined from the marginal frequencies under the usual Hardy–Weinberg equilibrium (HWE) assumption and that the maximum likelihood estimates of haplotype frequencies are consistent and asymptotically normal as the number of pools increases. The limiting covariance matrix is shown to be closely related to the extended hypergeometric distribution. Our results are used to derive Wald‐type tests for linkage disequilibrium (LD) coefficient using pooled data. It is discovered that pooling is not efficient in testing weak LD despite its efficiency in estimating haplotype frequencies. We also show by simulations that the proposed LD tests are robust to slight deviation from HWE and to minor genotype error. Applications to two real angiotensinogen gene data sets are also provided. Copyright © 2008 John Wiley & Sons, Ltd.
Saturation throughput analysis of multi‐rate IEEE 802.11 wireless networks
Authors: Deng Der‐Jiunn , Li Bin , Huang Lianfen , Ke Chih‐Heng , Huang Yueh‐Min 
Published: August 2008

AbstractIEEE 802.11 protocol supports adaptive rate mechanism, which selects the transmission rate according to the condition of the wireless channel, to enhance the system performance. Thus, research of multi‐rate IEEE 802.11 medium access control (MAC) performance has become one of the hot research topics. In this paper, we study the performance of multi‐rate IEEE 802.11 MAC over a Gaussian channel. An accurate analytical model is presented to compute the system saturation throughput. We validate our model in both single‐rate and multi‐rate networks through various simulations. The results show that our model is accurate and channel error has a significant impact on system performance. In addition, our numerical results show that the performance of single‐rate IEEE 802.11 DCF with basic access method is better than that with RTS/CTS mechanism in a high‐rate and high‐load network and vice versa. In a multi‐rate network, the performance of IEEE 802.11 DCF with RTS/CTS mechanism is better than that with basic access method in a congested and error‐prone wireless environment. Copyright © 2008 John Wiley & Sons, Ltd.
Elective Resection for Diverticular Disease: An Evidence‐Based Review
Authors: Collins D. , Winter D. C. 
Published: August 2008

AbstractControversy exists as to the most appropriate management of patients following two episodes of diverticulitis. Despite a growing body of new evidence challenging the concept of elective sigmoid resection after a patient experiences two attacks of diverticulitis, we continue to base our practice on outdated studies carried out more than 30 years ago. The recommendation that patients undergo elective sigmoid resection after two attacks of acute diverticulitis should be re‐evaluated as it is generally inappropriate and is not cost effective. Elective resection for uncomplicated diverticulitis does not alter outcome, nor does it decrease mortality or prevent complications of the disease. In fact, based on current literature, 18 patients would have to undergo elective operation to prevent one emergency surgery. This article aims to review the current evidence for elective resection following episodes of diverticular disease and addresses emerging controversies in the management of this disease.
Flaxseed oil prevents trans-10, cis-12-conjugated linoleic acid-induced insulin resistance in mice
Authors: Kelley Darshan S. , Vemuri Madhuri , Adkins Yuriko , Gill Sher Himmat S. , Fedor Dawn , Mackey Bruce E. 
Published: August 2008

Insulin resistance (IR) and non-alcoholic fatty liver disease (NAFLD) are found in 35 and 30 % of US adults, respectively. Trans-10, cis-12-conjugated linoleic acid (CLA) has been found to cause both these disorders in several animal models. We hypothesised that IR and NAFLD caused by CLA result from n-3 fatty acid deficiency. Pathogen-free C57BL/6N female mice (aged 8 weeks; n 10) were fed either a control diet or diets containing trans-10, cis-12-CLA (0·5 %) or CLA+flaxseed oil (FSO) (0·5 %+0·5 %) for 8 weeks. Weights of livers, concentration of circulating insulin, values of homeostatic model 1 (HOMA1) for IR and HOMA1 for β cell function were higher by 160, 636, 985 and 968 % in the CLA group compared with those in the control group. FSO decreased fasting glucose by 20 % and liver weights by 37 % compared with those in the CLA group; it maintained circulating insulin, HOMA1-IR and HOMA1 for β cell function at levels found in the control group. CLA supplementation decreased n-6 and n-3 wt% concentrations of liver lipids by 57 and 73 % and increased the n-6:n-3 ratio by 58 % compared with corresponding values in the control group. FSO increased n-6 and n-3 PUFA in liver lipids by 33 and 342 % and decreased the n-6:n-3 ratio by 70 % compared with corresponding values in the CLA group. The present results suggest that some adverse effects of CLA may be due to n-3 PUFA deficiency and that these can be corrected by a concomitant increase in the intake of α-linolenic acid, 18 : 3n-3.
James Jackson Jarves's Art Criticism: Aesthetic Classifications and Historiographic Consequences
Authors: GEORGI KAREN L. 
Published: August 2008

Looking at the methodological principles and rhetorical forms that structure James Jackson Jarves's often-cited 1864 book The Art-Idea, this essay reconsiders Jarves's role in the historiography of American art. Jarves has long been associated with post-Civil War shifts toward international aesthetic trends, which eroded the native bias in favor of verisimilitude and anecdote. He is thought to mark a turning point. His texts, however, only partially corroborate the reputation. Here, firstly, I reread Jarves's art theory to suggest what were the aesthetic preferences he hoped to foster among Americans, and why. Secondly, I propose that the reputed Jarves fulfills an apparently unrecognized need in the subdiscipline of American art history – a fundamental understanding of American art as automatically, necessarily, indexical. It is primarily a manifestation of American culture, and more specifically American culture as defined by change, growth, disruption, reintegration.
The Ruins of Pompey: The Euro-American Invention of Native American Prehistory and the Gothic Mode in Joshua V. H. Clark's Onondaga
Authors: SLOAN DE VILLO 
Published: August 2008

In the United States between the approximate dates of 1800 and 1870, a group of writers whom I call Romantic Antiquarians invented and disseminated a narrative of Native American prehistory radically at odds with the later findings of modern archaeologists. Romantic Antiquarian discourse borrows from the themes and modes of literary Romanticism, and textual analysis of this work (which enjoyed widespread public acceptance before it was profoundly discredited) offers insights into the complex relationship between Native and Euro-American cultures. This essay provides an overview of the Romantic Antiquarian movement and explores its ideology. The writing of antiquarian Joshua V. H. Clark of New York is examined closely, including his theories concerning the Iroquois, his relationship with E. G. Squier, and his use of the Gothic mode.
In the Hindutva Laboratory: Pogroms and Politics in Gujarat, 2002
Authors: SPODEK HOWARD 
Published: August 2008

AbstractCommunal violence wracked the state of Gujarat and the city of Ahmedabad once again in 2002, leaving some 2,000 people dead. Because the ruling BJP party had proclaimed Gujarat the ‘Laboratory of Hindutva’, analysts throughout India saw the violence as BJP policy and debated its possible spillover effects elsewhere. This paper finds that in a period already marked by stressful economic and cultural change and attended by political uncertainty, some BJP leaders gambled that an attack on Gujarat's Muslims, and on the rule of law in general, would attract followers and voters. Their gamble proved correct at least in the short run. This paper examines the cultural, social, geographical and educational restructuring that is occurring, through legal and illegal struggles, and the impact of the violence upon these processes. It examines the declining status of Muslims as a result of continuous propaganda against them. It analyzes the degree to which the state was damaged as a result of the decision for violence and asks about the degree to which leaders do, or do not, wish to ‘put it behind them’, and suggests that Ahmedabad's problems are widely shared in both the developing and developed worlds.
Strategies to enhance radiosensitivity in breast cancer
Authors: Formenti S. C. 
Published: August 2008

AbstractRadiotherapy is an important component in the treatment of breast cancer. However, the individual tumor response to radiation is variable, reflecting both the intrinsic properties of the tumor and its microenvironment as well as the different, inherited sensitivity of the patient's normal tissue when exposed to the effect of ionizing radiation. These differences have inspired research to discover the underlying signal transduction pathways and to understand when they pertain to the tumor, the host or both. In fact, understanding the mechanisms underlying radiosensitivity of breast cancer not only does it permit to design more effective radiation treatments, but it sheds light on the complexities of tumor-host interactions in this disease.
Conjugated Linoleic Acid‐induced Fat Loss Dependence on Δ6‐desaturase or Cyclooxygenase
Authors: Hargrave‐Barnes Kimberly M. , Azain Michael J. , Miner Jess L. 
Published: August 2008

Objective:To determine whether conjugated linoleic acid (CLA)–induced body fat loss is dependent upon metabolism of CLA by Δ6‐desaturase, cyclooxygenase, or lipoxygenase.Methods and Procedures:Mice were fed diets with or without CLA and inhibitors to either Δ6‐desaturase (SC‐26196), cyclooxygenase (aspirin), or lipoxygenase (nordihydroguaiaretic acid (NDGA)) for 2 weeks. Body fat percent, lean mass, fat pad weights, liver weight, and fatty acid concentrations were determined. A Δ6‐desaturase index was calculated, and adipose tissue prostaglandin E2(PGE2) and leukotriene B4(LTB4) concentrations were determined to confirm enzyme inhibition.Results:Inhibition of Δ6‐desaturase and cyclooxygenase were confirmed. CLA caused a loss of body fat (P< 0.001). The body fat loss was blocked (P= 0.08) by the Δ6‐desaturase inhibitor at a dose that decreased (P< 0.05) the calculated index. Aspirin and NDGA had no effect on body fat and did not interact with CLA.Discussion:Inhibition of Δ6‐desaturase prevented CLA from being able to cause a body fat loss. Therefore, a desaturated metabolite of CLA appears to be involved in the CLA antiobesity effect. This effect of CLA does not seem dependent upon cyclooxygenase. Because lipoxygenase activity was not blocked by NDGA, we cannot draw conclusions about its importance in mediating the antiobesity effect of CLA.