bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐pressure Raman study on two modifications of BaAl2Si2
Authors: Shimizu H. , Kume T. , Narita Y. , Sasaki S. , Kikudome T. , Yamanaka S. 
Published: November 2006

AbstractThe new compound BaAl2Si2 exists in two structural modifications at ambient condition; a clathrate‐like low‐pressure phase α‐BaAl2Si2 and a layered high‐pressure phase β‐BaAl2Si2. Raman scattering of α‐BaAl2Si2 and β‐BaAl2Si2 has been measured at 1 bar and room temperature, and that of α‐BaAl2Si2 under high pressures up to 20 GPa. For α‐BaAl2Si2, 17 Raman vibrational modes were observed at frequency of 40–450 cm–1, which is almost consistent with the group theoretical analysis. Low‐frequency vibrational modes associated with Ba atoms in the polyhedrons were found around 65–80 cm–1 compa‐ rable to the typical clathrate Ba8Si46. The 4 Raman bands predicted by the group theory were found for β‐BaAl2Si2. Pressure dependence of Raman modes for α‐BaAl2Si2 indicates the existence of phase transformation at about 20 GPa, which was irreversible with decreasing pressure. The decompressed α‐BaAl2Si2 from 20 GPa to 1 bar shows Raman spectrum close to that of β‐BaAl2Si2 at ambient pressure. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and optical high‐pressure study of spinel‐type MnIn2S4
Authors: Manjón F. J. , Segura A. , Amboage M. , Pellicer‐Porres J. , Sánchez‐Royo J. F. , Itié J. P. , Flank A. M. , Lagarde P. , Polian A. , Ursaki V.V. , Tiginyanu I. M. 
Published: November 2006

AbstractWe report a combined study of the structural and electronic properties of the spinel‐type semiconductor MnIn2S4 under high pressures by means of X‐ray diffraction (ADXRD), X‐ray absorption (XAS), and optical absorption measurements. The three techniques evidence a reversible structural phase transition near 7 GPa, that according to ADXRD measurements is to a double‐NaCl structure. XAS measurements evidence predominant tetrahedral coordination for Mn in the spinel phase that does not noticeably change with increasing pressure up to the phase transition. XAS measurements indicate that the static disorder increases considerably when the sample reverts from the double‐NaCl phase to the spinel phase. Optical absorption measurements show that the direct gap of MnIn2S4 exhibits a nonlinear behaviour with a positive pressure coefficient at pressures below 2.5 GPa and a negative pressure coefficient between 2.5 and 7 GPa. The pressure behavior of the bandgap seems to be affected by the defect concentration. The double‐NaCl phase also exhibits a bandgap with a negative pressure coefficient. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoluminescence of CdSe quantum dots with Zn0.38Cd0.23Mg0.39Se barriers under hydrostatic pressure
Authors: Reparaz J. S. , Goñi A. R. , Alonso M. I. , Perez‐Paz M. N. , Tamargo M. C. 
Published: November 2006

AbstractWe have investigated the pressure dependence of the room‐temperature photoluminescence (PL) of self‐assembled CdSe quantum dots (QDs) with quaternary ZnCdMgSe barriers. Four samples with different CdSe deposition times, i.e. different average dot size, were studied. Samples exhibit a very distinct emission energy covering the visible spectrum from the red to the blue. We found, however, a similar pressure coefficient of around 47 meV/GPa for the PL emission of all samples. This value is close to that of bulk CdSe, which gives evidence that dot and quaternary barrier material have a similar compressibility. In contrast, the PL linewidth displays a clear trend with respect to the emission energy, the PL line being broader for the smaller dots emitting in the blue. This is explained by taking into account the huge band‐gap offset of ≈1 eV between dot and barrier and considering quantum confinement effects within a very simplistic infinitely deep square‐well model. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pressure dependence of photoluminescence of InAs/InP self‐assembled quantum wires
Authors: Ruiz‐Castillo M. , Segura A. , Sans J. A. , Martínez‐Pastor J. , Fuster D. , González Y. , González L. 
Published: November 2006

AbstractThis paper investigates the electronic structure of self‐assembled InAs quantum wires (QWrs), grown under different conditions by molecular beam epitaxy on InP, by means of photoluminescence measurements under pressure. In samples with regularly distributed QWrs, room pressure photoluminescence spectra consist of a broad band centred at about 0.85 eV, which can be easily de‐convoluted in a few Gaussian peaks. In samples with isolated QWrs, photoluminescence spectra exhibit up to four clearly resolved bands. Applying hydrostatic pressure, the whole emission band monotonously shifts towards higher photon energies with pressure coefficients ranging from 72 to 98 meV/GPa. In contrast to InAs quantum dots on GaAs, quantum wires photoluminescence is observed up to 10 GPa, indicating that InAs QWrs are metastable well above pressure at which bulk InAs undergoes a phase transition to the rock‐salt phase (7 GPa). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Band gap dependence of the recombination processes in InAs/GaAs quantum dots studied using hydrostatic pressure
Authors: Marko I. P. , Adams A. R. , Sweeney S. J. , Massé N. F. , Krebs R. , Reithmaier J. P. , Forchel A. , Mowbray D. J. , Skolnick M. S. , Liu H. Y. , Groom K. M. , Hatori N. , Sugawara M. 
Published: November 2006

AbstractWe present the results based upon a systematic study of the properties of quantum dot (QD) lasers with emission wavelengths around 0.98 and 1.3 µm at room temperature and atmospheric pressure. To investigate the radiative and non‐radiative components of the threshold current, we studied the temperature and high hydrostatic pressure dependencies of spontaneous and stimulated emission. Although important parameters such as lasing wavelength, QD density, ridge width, cavity length, threshold current density (J th) varied greatly, we found that all the lasers have nearly the same dependence of the radiative component, J rad, on band gap when it was tuned by the application of high pressure. It was observed that J rad increases strongly with band gap. Therefore the different dependencies of J th are explained in terms of the relative importance of different non‐radiative recombination mechanisms, such as Auger recombination and thermal carrier escape. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cross‐layer design for call admission control of a high‐capacity GEO satellite network with on‐board cross‐connect
Authors: Qingyang Hu Rose , Qian Yi , Cheng Yu , Kota Sastri 
Published: November 2006

AbstractThis paper addresses cross‐layer design of end‐to‐end call admission control and beam‐to‐beam connectivity provisioning for a high‐capacity multi‐beam GEO satellite network with on‐board cross‐connectivity. On‐board satellite switching is a technology designed to offer heterogeneous services, especially in demographically dispersed areas. Nevertheless, full on‐board switching techniques are far from maturity. Their implementations have been proven expensive and difficult. There are also high risks involved in launching satellites for the stationary orbit surrounding the Earth. As a substitute, a satellite network with on‐board cross‐connect is devised in this paper. Connectivity provisioning and call admission control mechanisms associated with such a network are also presented. Simulation studies are conducted to show the effectiveness of the proposed mechanisms. Copyright © 2006 John Wiley & Sons, Ltd.
Semantic Web approach to smart link generation for Web navigations
Authors: Kao Shang‐Juh , Hsu I‐Ching 
Published: November 2006

AbstractThe rapid development of the Internet has led to diverse applications of accessing various Web resources, such as Web pages, XML documents, pictures and video and audio files. Intelligently discovering how these Web resources are related in order to enable effective Web surfing is a current challenge in Internet development. The XML Link Language (XLink), which is a W3C recommendation for describing the relationships among Web resources, is a potential solution to this problem. However, XLink is still short of knowledge representation in handling computer‐interpretable effects, such as dynamic link generations. This study attempts to integrate knowledge into XLink by defining a multi‐layered semantic framework. The proposed framework is across four layers of the semantic Web stack, including the URI layer, XML (XLink) layer, ontology layer and rule layer, to facilitate machine understanding. The ontology, which is based on description logics, provides sound reasoning, while the rule is a logic program built on top of an ontology to support complementary inference capabilities. Based on the multi‐layered semantic framework, an intelligent XLink shell, called XLinker, is also developed to facilitate three semantic approaches of linking associations, i.e. XLink‐based metadata, ontology‐based reasoning and rule‐based inference. To demonstrate the feasibility of XLinker, an XLink Transcoding Web Server is also implemented to reveal smart hyperlink generation for Web navigations. Copyright © 2006 John Wiley & Sons, Ltd.
OmniCon: a Mobile IP‐based vertical handoff system for wireless LAN and GPRS links
Authors: Sharma Srikant , Baek Inho , Chiueh Tzi‐cker 
Published: November 2006

AbstractWi‐Fi based hotspots offer mobile users broadband wireless Internet connectivity in public work spaces and corporate/university campuses. Despite the aggressive deployment of these hotspots in recent years, high‐speed wireless Internet access remains restricted to small geographical areas due to the limited physical coverage of wireless LANs. On the other hand, despite their lower throughput, cellular networks have a significantly wider coverage and are thus much more available. Recognizing that 2.5G or 3G cellular networks can effectively complement wireless LANs, we set out to develop a vertical handoff system that allows mobile users to seamlessly fall back to such cellular networks as the general packet radio service (GPRS) or 3G whenever wireless LAN connectivity is not available. The resulting handoff mechanism allows a network connection of a mobile node to operate over multiple wireless access networks in a way that is transparent to end user applications. In this paper, we present the design, implementation, and evaluation of a fully operational vertical handoff system, called OmniCon, which enables mobile nodes to automatically switch between wireless LAN and GPRS, based on wireless LAN availability, by introducing a simple extension to the existing Mobile IP implementation. We discuss the design issues in the proposed vertical handoff system for heterogeneous networks, including connection setup problems due to network address translation, and the disparity in link characteristics between wireless LANs and GPRS. A detailed performance evaluation study of the OmniCon prototype demonstrates its ability to migrate active network connections between these two wireless technologies with low handoff latency and close to zero packet loss. Copyright © 2006 John Wiley & Sons, Ltd.
The Esperanto Broker: a communication platform for nomadic computing systems
Authors: Cotroneo Domenico , Migliaccio Armando , Russo Stefano 
Published: November 2006

AbstractThere is an increasing demand for middleware for nomadic computing applications. Owing to the inherent characteristics of such environments, these platforms have to address two fundamental issues: (i) device disconnections and the limitations of wireless networks may force users to experience short periods of service unavailability; and (ii) the complexity to design and develop next‐generation mobile computing applications. This paper proposes the Esperanto Broker (EB), a communication platform that addresses mobility issues via an integrated approach, i.e. at data‐link, network, and middleware levels. Decoupling interactions are achieved via a tuple‐space underlying infrastructure. To support developers with advanced services, the EB enhances the distributed objects computing model providing the abstraction for the communication paradigms standardized by the W3C. Esperanto applications can be modeled as sets of objects that are distributed over mobile devices, which communicate via remote method invocations (RMIs). RMIs natively implement pull and push models, in both one‐to‐one and one‐to‐many multiplicity. The paper focuses on the EB design issues, essential aspects of the implementation, and performance evaluations of the implemented prototype. Copyright © 2006 John Wiley & Sons, Ltd.
Test characteristics of placental location screening by transabdominal ultrasound at 18–20 weeks
Authors: Olive E. C. , Roberts C. L. , Nassar N. , Algert C. S. 
Published: November 2006

AbstractObjectivesTo determine the test characteristics of a second‐trimester transabdominal fetal anomaly scan in screening for placenta previa.Patients and methodsThis was a case‐control study carried out at a tertiary obstetric hospital involving 54 women (0.5% of the total number booked for antenatal care and delivery at the center) with clinically significant placenta previa at the time of delivery, and 168 randomly selected controls who attended for antenatal care and delivery in 2000–2003. Sensitivity, specificity and false positive rate of the placenta–os measurement in the second‐trimester transabdominal fetal anomaly scan for identification of clinically significant placenta previa were assessed.ResultsWomen with placenta previa at delivery had significantly different second‐trimester placenta–os measurements from those of controls (P < 0.0001). For women with placenta previa, the mean (standard deviation) placenta–os measurement was −0.96 cm (1.95) vs. 4.15 cm (1.77) for controls (P < 0.0001). Using the anomaly scan as a screening test for placenta previa with a placenta–os measurement cut‐off point of ≤ 2 cm, all cases of placenta previa should be identified, but 11.1% (95% CI, 7.1–14.8) of women without placenta previa would have false positive results. At cut‐off points of 3 cm and 1.5 cm the false positive rates were 25.7% (95% CI, 18.8–30.2%) and 6.6% (95% CI, 3.8–9.6%), respectively, but at 1.5 cm 3.8% of cases would be missed.ConclusionsThe second‐trimester transabdominal fetal anomaly scan is a useful screening test for placenta previa. However, because of false positives among the much larger population of women without placenta previa, we estimate that with a cut‐off point of ≤2 cm, 23 women would have to be followed up to confirm one true placenta previa. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Subtelomeric rearrangements and 22q11.2 deletion syndrome in anomalous growth‐restricted fetuses with normal or balanced G‐banded karyotype
Authors: Chen M. , Hwu W.‐L. , Kuo S.‐J. , Chen C.‐P. , Yin P.‐L. , Chang S.‐P. , Lee D.‐J. , Chen T.‐H. , Wang B.‐T. , Lin C.‐C. 
Published: November 2006

AbstractObjectiveTo determine the frequencies of cryptic subtelomeric rearrangements and 22q11.2 deletion in anomalous growth‐restricted fetuses with normal or balanced G‐banded karyotypes.MethodsThis was a study of 27 consecutive fetuses at a median gestational age of 26 (range, 19–33) weeks, that had intrauterine growth restriction (IUGR) as well as at least one major structural anomaly, and a normal or balanced G‐banded karyotype. The median maternal age was 29 (range, 17–39) years. Fluorescence z in‐situ hybridization (FISH) diagnosis of the cultured amniocytes with the probe TUPLE 1, and then the Chromoprobe Multiprobe‐T® system were used, respectively, to screen for the frequency of 22q11.2 deletion syndrome and subtelomeric rearrangements involving the 41 unique chromosome ends (i.e. excluding the five short arms of acrocentric autosomes (no. 13, 14, 15, 21 and 22)). Those that had suspected deleted subtelomeres were reanalyzed with a specific subtelomeric probe, TelVysion®.ResultsOf the 27 fetuses, three (11%) were affected with 22q11.2 deletion syndrome and two (7.4%) had subtelomeric deletions (one monosomy 21q22.3, one monosomy 1p36.3). Of the 11 fetuses with congenital heart defects, three (27.3%) had 22q11.2 deletion syndrome and one (9.1%) had monosomy 1p36.3. In the remaining 16 fetuses without congenital heart defects, none had 22q11.2 deletion syndrome. However, one (6.3%) had cryptic rearrangement involving subtelomeres.ConclusionPrenatal subtelomeric FISH screening is technically feasible using cultured amniocytes. We propose that 22q11.2 deletion syndrome and cryptic subtelomere rearrangements may be important etiologies of fetuses with IUGR and at least one structural anomaly, along with a normal karyotype or one that is balanced by traditional G‐banding. Fetuses with congenital heart defects and IUGR should undergo FISH to exclude 22q11.2 deletion syndrome. In fetuses with IUGR and at least one major structural anomaly but without congenital heart defects, screening of subtelomeric rearrangements may contribute to further elucidation of the underlying etiology. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Use of a confidence scale in reporting postmortem fetal magnetic resonance imaging
Authors: Breeze A. C. G. , Cross J. J. , Hackett G. A. , Jessop F. A. , Joubert I. , Lomas D. J. , Set P. A. K. , Whitehead A. L. , Lees C. C. ,   for the Cambridge Post‐mortem MRI Study Group
Published: November 2006

AbstractObjectivesPostmortem magnetic resonance imaging (MRI) may be an alternative to conventional autopsy. However, it is unclear how confident radiologists are in reporting such studies. We sought to determine the confidence with which radiologists report on various fetal organs by developing a scale to express their confidence of normality and abnormality, and to place this in the context of a pathological diagnosis of whether the organ was in fact normal or abnormal.MethodsThirty fetuses, aged 16–39 gestational weeks and weighing 61–3270 g, underwent postmortem MRI prior to conventional autopsy. MRI studies were reported by two radiologists with access to the clinical and sonographic history: a neuroradiologist, reporting head and neck, and a pediatric radiologist, reporting thorax, abdomen and pelvis. Radiologists used a scale (0 = definitely abnormal, 100 = definitely normal, 50 = unable to comment) to indicate their confidence of anatomical structures being normal or abnormal, using a checklist. Conventional autopsies were performed by pediatric pathologists blinded to the MRI findings, and these were considered the reference standard.ResultsMost normal fetal organs had high scores on postmortem MRI, with median confidence scores above 80. However, the atrioventricular valves, duodenum, bowel rotation and pancreas proved more difficult to assess, with median scores of 50, 60, 60 and 62.5, respectively. Abnormal cardiac atria and ventricles, kidneys, cerebral hemispheres and corpus callosum were always detected with high or moderate degrees of confidence (median scores of 2.5, 5, 0, 0 and 30 respectively). However, in two cases with abnormal cardiac outflow tracts, both cases scored 50. Kappa values, assessing agreement between MRI diagnoses of abnormality and autopsy, were high for the brain (0.83), moderate for the lungs (0.56) and fair for the heart (0.33).ConclusionsThis scoring system represents an attempt to define the confidence of radiologists to report varying degrees of normality and abnormality following z ex‐utero fetal MRI. While most fetal anatomy is clearly visualized on postmortem MRI, radiologists may lack confidence reporting such studies and there are particular problems with assessment of some cardiac and gastrointestinal structures, both normal and abnormal. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
When Should We Be Concerned about Pancreatic Necrosis? Analysis from a Single Institution in Mexico City
Authors: Remes‐Troche José M. , Uscanga Luis F. , Peláez‐Luna Mario , Duarte‐Rojo Andres , González‐Balboa Paola , Teliz Marco Antonio , Chan‐Nunez Carlos , Campuzano Manuel , Robles‐Díaz Guillermo 
Published: November 2006

AbstractBackground/AimAlthough pancreatic necrosis classifies acute pancreatitis (AP) as severe, many patients with tomographic evidence of necrosis never develop systemic complications. Our aim was to analyze the incidence of pancreatic necrosis, organ failure (OF), and the relationship between them.MethodsMedical records from 165 patients with a first AP episode and in whom a contrast‐enhanced computed tomography (CECT) was performed were analyzed. Pancreatic necrosis was diagnosed as non‐enhancing areas of the pancreas on the CECT and was graded as <30%, 30%–50%, and >50%. Pancreatic infection was assessed by guided percutaneous aspiration. Organ failure was defined according to the Atlanta criteria.ResultsOf 165 patients (mean age 42 years, 85 men), 54 (33%) had pancreatic necrosis. Necrosis was graded as <30% in 25 subjects (46%), 30%–50% in 16 (30%), and >50% in 13 (24%). Pancreatic infection was diagnosed in 14 cases (26%). Organ failure occurred in 49 patients: in 20 patients (37%) with necrosis, and in 29 patients (26%) without necrosis (P = 0.20). Extensive pancreatic necrosis (>50%) (P < 0.05) and infected necrosis (P < 0.05) were significantly associated with OF. Eight patients, all of them with OF, died. In 6 of these cases infected pancreatic necrosis was present.ConclusionsPatients with pancreatic necrosis are not necessarily at risk of developing OF. However, it should be considered an important risk factor when the necrotizing process compromises more than 50% of the gland and is infected.
Homocysteine and atherothrombosis
Authors: Falk Erling , Zhou Ji , Møller Jan 
Published: November 2006

AbstractAtherosclerosis with or without thrombosis superimposed is the most frequent cause of ischemic heart disease (IHD), peripheral arterial disease, and a main cause of stroke. Conflicting results have been reported in genetic, observational, and experimental studies on the relationship between homocysteine and these atherothrombotic diseases. Although cardiovascular complications are common in homocystinuric pateints (severe hyperhomocysteinemia), IHD, the most frequent manifestation of atherothrombosis in the general population, appears to be rare. On the basis of findings in individuals with hyperhomocysteinemia of genetic origin, there is in fact no clear evidence for a causal role of homocysteine in the pathogenesis of atherothrombotic disease, and the positive association between plasma homocysteine and II ID observed in many, but not all epidemiologic studies does not prove causality. To infer causality from observational studies, there should be a temporal, consistent, strong, independent, graded (dose‐response effect), and duration‐dependent relationship between exposure and outcomes, and a biologically plausible mechanism should exist. The relationship between plasma homocysteine levels and IHD does not fulfill these criteria beyond reasonable doubt. In the general population, plasma homocysteine levels are to a great extent determined by dietary habits, and plasma homocysteine could be a marker, or a consequence, of atherothrombosis and/or risk‐associated behavior (e.g., a diet low in fruits and vegetables) rather than a cause of atherothrombosis. Experimentally, hyperhomocysteinemia is not in itself atherogenic in normal animals with relatively low plasma cholesterol levels. The homocysteine theory of atherosclerosis should be tested more thoroughly in hypercholesterolemic animals that develop atherosclerosis spontaneously to determine whether elevated plasma homocysteine levels are harmful under atherogenic conditions. A causal role of homocystein in atherothrombotic disease remains to be established.