bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion-acoustic double layers in magnetized plasma consisting of warm adiabatic ions and non-thermal electrons having vortex-like velocity distribution: existence and stability
Authors: DAS JAYASREE , BANDYOPADHYAY ANUP , DAS K. P.
Published: August 2007

A combined Schamel's modified Korteweg–de Vries–Zakharov– Kuznetsov (S–KdV–ZK) equation efficiently describes the nonlinear behaviour of ion-acoustic waves in a plasma consisting of warm adiabatic ions and non-thermal electrons (due to the presence of fast energetic electrons) having vortex-like velocity distribution function (due to the presence of trapped electrons), immersed in a uniform (space-independent) and static (time-independent) magnetic field, when the vortex-like velocity distribution function of electrons approaches the non-thermal velocity distribution function of electrons as prescribed by Cairns et al. (1995 Electrostatic solitary structures in non-thermal plasmas.Geophys. Res. Lett.22, 2709–2712), i.e. when the contribution of trapped electrons tends to zero. This combined S–KdV–ZK equation admits a double-layer solution propagating obliquely to the external uniform and static magnetic field. The condition for the existence of this double-layer solution has been derived. The three-dimensional stabilities of the double-layer solutions propagating obliquely to the external uniform and static magnetic field have been investigated by the multiple-scale perturbation expansion method of Allen and Rowlands (1993 Determination of growth rate for linearized Zakharov–Kuznetsov equation.J. Plasma Phys.50, 413–424; 1995 Stability obliquely propagating plane solitons of the Zakharov–Kuznetsov equation.J. Plasma Phys.53, 63–73). It is found that the double-layer solutions of the combined S–KdV–ZK equation are stable at the lowest order, i.e. up to the orderk, wherekis the wave number of perturbation.
Prevalence of Helicobacter pylori infection among Egyptian children: impact of social background and effect on growth
Authors: Mohammad Mahmoud A , Hussein Laila , Coward Andy , Jackson Sarah J
Published: August 2007

Objective

The study aim was to assess the prevalence of Helicobacter pylori infection in Egyptian schoolchildren and its effect on growth parameters.

Design

A cross-sectional population-based study was conducted among 286 schoolchildren (168 boys and 118 girls), with a mean age of 11.04 ± 0.19 years, to determine the prevalence of H. pylori. The presence of the bacterium was assessed using the [13C]urea breath test. Relevant personal and socio-economic data on risk factors for infection were collected. Height and weight were analysed in relation to H. pylori infection.

Results

The overall prevalence of H. pylori infection was 72.38%. Attending school in a socially deprived area and residing in an overcrowded home were the major risk factors for infection. Differences between infected and non-infected children were significant with regard to body weight and height (weight: 39.5 ± 1.0 vs. 44.6 ± 1.8 kg, P = 0.05; height: 139.9 ± 1.3 vs. 144.2 ± 2.1 cm; P = 0.009). The number of children (both boys and girls) falling below the 5th percentile of height-for-age was significantly higher in infected than non-infected children (P = 001), similarly for Z-scores for height-for-age below –2.0 (P = 0.003).

Conclusion

The results demonstrate not only that the prevalence of H. pylori infection is extremely high among Egyptian schoolchildren, but also that the adverse effects of the infection reach far beyond the stomach. Evidence of the burden of infection on growth failure is presented.
Beurteilung der Eignung im Rahmen des UVG – Nichteignungsverfügung / bedingte Eignungsverfügung
Authors: Jost  , Rast
Published: August 2007

Zur Verhütung von Berufskrankheiten oder in der Person des Arbeitnehmenden liegenden Unfallgefahren kann im Rahmen der arbeitsmedizinischen Vorsorge eine Nichteignungsverfügung oder bedingte Eignungsverfügung durch die Suva erlassen werden. Der Erlass dieser Personenverfügung ist bei obligatorisch UVG-versicherten Arbeitnehmenden möglich, nicht hingegen bei selbstständig Erwerbenden und nur bei einer erheblichen gesundheitlichen Gefährdung. Rund die Hälfte der Nichteignungsverfügungen ist wegen Berufskrankheiten der Haut, die andere Hälfte wegen Berufskrankheiten der Atemwege angezeigt. Am häufigsten werden Nichteignungsverfügungen für Arbeiten mit Einwirkungen gegenüber Mehlstäuben, Zement, Isocyanaten und Coiffeurstoffen notwendig. Geldleistungen des UVG-Versicherers in der Form eines Übergangstaggeldes oder einer Übergangsentschädigung haben zum Ziel die finanziellen Folgen einer Nichteignungsverfügung abzufedern. Weitere Anlaufstellen nach einer Nichteignungsverfügung sind die Arbeitslosenversicherung und für die Berufsberatung und Umschulung die Invalidenversicherung.
Dans quelle mesure les maladies cardiovasculaires sont-elles la cause d’incapacité de travail et d’invalidité en Suisse?
Authors: Darioli  , Perdrix
Published: August 2007

Les maladies cardiovasculaires (MCV) constituent dans tous les pays industrialisés une cause majeure de morbidité et de mortalité, y compris en Suisse où elles figurent en tête des maladies diagnostiquées au cabinet médical (12.4%) et des motifs d’hospitalisation (9.6%) en 2004/2005. Cependant, les données statistiques de l’incapacité de travail et d’invalidité consécutives aux MCV demeurent lacunaires. Basée sur une revue de la littérature médicale et sur les statistiques officielles, les MCV ne représentaient que 2.3% des motifs d’arrêt de travail > 6 jours délivrés par les médecins de 1ers recours pour les patients de moins de 65 ans. Par ailleurs, les MCV ne correspondaient qu’à 2.5% de l’ensemble des rentes d’invalidité accordées aux femmes, ce taux étant de 5.5% chez les hommes en 2006. Entre 1987 et 2006, la proportion de diagnostics de MCV établis au cabinet médical a régressé de 14.6 à 12.4% (–15%), et plus encore celle des rentes de l’Assurance invalidité (AI) pour MCV qui a passé de 9.6 à 4.1% (–57%). L’ampleur de ces changements soulignent la nécessité de pouvoir disposer de données statistiques plus détaillées pour mesurer l’adéquation entre les dépenses consacrées à la prévention et le traitement des MCV et leur répercussion économique sur l’incapacité de travail et l’invalidité.
Rückkehr zur Arbeitsfähigkeit – wie ist dies zu erreichen?
Authors: Meck  , Maurer  , Wandl
Published: August 2007

Arbeits- und Erwerbsunfähigkeit verursachen in Deutschland hohe Kosten für die Privatwirtschaft und die Sozialversicherungsträger. Insbesondere für leistungsgeminderte Menschen ist die Rückkehr ins Arbeitsleben schwer. Um die zur Verfügung stehenden Mittel effizient zu nutzen, hat der Gesetzgeber die Rahmenbedingungen neu geregelt. Höhere Erfolgsraten verspricht hierbei ein durchgängiges, konsequentes Case-Management. Dies ist am Beispiel eines privaten Rehabilitationsdienstes aufgezeigt.
Arbeitsunfähigkeit, Erwerbsunfähigkeit und Invalidität bei entzündlichen Darmkrankheiten
Authors: Beglinger  , Gyr
Published: August 2007

Morbus Crohn und Colitis ulcerosa sind chronisch-entzündliche Darmerkrankungen, deren Ursache weiterhin ungeklärt bleibt. Leitsymptome beim M. Crohn sind Schmerzen, oft verbunden mit Gewichtsverlust und eine Reihe anderer intestinaler und/oder extraintestinaler Symptome (unter anderem Durchfall), während die Colitis ulcerosa klinisch charakterisiert ist durch Diarrhoen, die blutig sind und mit einer Anämie verbunden sein können. Beide Krankheiten können von extraintestinalen Manifestationen begleitet sein. Wichtig zum Verständnis der Krankheiten ist die Beobachtung, dass der Verlauf, die Ausdehnung, der Schweregrad der Erkrankung und die möglichen Komplikationen sehr variabel und nicht voraussehbar sind. Bei vielen Patienten werden lange Remissionsphasen von akuten entzündlichen Schüben unterbrochen, oft assoziiert mit Komplikationen. Aus versicherungstechnischer Perspektive ist dieser variable Verlauf ein großes Problem, da kaum Daten zur Arbeitsunfähigkeit zur Verfügung stehen und keine eindeutigen Voraussagen in Bezug auf langfristige Arbeitsunfähigkeit, Erwerbsunfähigkeit und Invalidität möglich sind.
First‐order reversal curve (FORC) diagrams of natural and cultured biogenic magnetic particles
Authors: Chen Amy P. , Egli Ramon , Moskowitz Bruce M.
Published: August 2007

First‐order reversal curve (FORC) diagrams are rapidly becoming a standard tool for characterizing magnetic particles because they simultaneously incorporate information regarding magnetostatic interaction and domain states. The simplest interpretation of FORC diagrams of single‐domain (SD) particles is based on the Neel interpretation of Preisach theory, which predicts that the FORC function is the product of a coercivity and an interaction field distribution. Although the underlying assumptions of this interpretation are not correct, a strictly quantitative model of weakly interacting SD grains proves that the distributions of coercivities and interaction fields can be retrieved from a FORC diagram. To test this model, we present the possibility of a quantitative interpretation of FORC diagrams, and we present measurements of samples containing magnetosomes from cultures of magnetotactic bacteria and from a lake sediment. Two samples are investigated under the electron microscope to characterize the geometrical arrangement of the particles. We find that the clustering of otherwise similar particles has a strong influence on FORC diagrams. We also obtained a crude estimate of packing densities form the FORC diagrams, which were consistent with transmission electron microscopy observations and measurements of the anhysteretic remanent magnetization.
Chemical compositions at Mars landing sites subject to Mars Odyssey Gamma Ray Spectrometer constraints
Authors: Karunatillake Suniti , Keller John M. , Squyres Steven W. , Boynton William V. , Brückner Johannes , Janes Daniel M. , Gasnault Olivier , Newsom Horton E.
Published: August 2007

The Mars Odyssey Gamma Ray Spectrometer (GRS) is the first instrument suite to return elemental abundances throughout the midlatitudes of Mars. Concentrations of Cl, Fe, H, K, Si, and Th have been determined to tens of centimeter depths as mass fractions with reasonable confidence. Comparing such data with, or normalizing them to, in situ compositional data is difficult due to issues such as dramatic differences in spatial resolution; difficulties in convolving densities, abundances, and compositions of different regolith components; and a limited number of elements observed in common. We address these concerns in the context of the GRS, using Si at Pathfinder to normalize remote data. In addition, we determine representative in situ compositions for Spirit (both with and without Columbia Hills rocks), Opportunity, and Viking 1 landing sites using GRS‐derived H content to hydrate the soil component. Our estimate of the Si mass fraction at Pathfinder, with 13% areal fraction of rocks, is 21%. The composition of major elements, such as Si and Fe, is similar across the four landing sites, while minor elements show significant variability. Areal dominance of soil at all four landing sites causes representative compositions to be driven by the soil component, while proportionally large uncertainties of bulk densities dominate the net uncertainties. GRS compositional determinations compare favorably with the in situ estimates for Cl and K, and for Si by virtue of the normalization. However, the GRS‐determined Fe content at each landing site is consistently higher than the in situ value.
Modeling cross‐shore sandbar behavior on the timescale of weeks
Authors: Ruessink B. G. , Kuriyama Y. , Reniers A. J. H. M. , Roelvink J. A. , Walstra D. J. R.
Published: August 2007

We compare predictions of a coupled, wave‐averaged, cross‐shore waves‐currents‐bathymetric evolution model to observations of onshore and offshore nearshore sandbar migration. The observations span a 10‐ and 44‐day period with onshore/offshore bar migration at Duck, North Carolina, and at Hasaki, Kashima Coast, Japan, respectively, a 3.5‐month period of onshore bar migration at Duck, and a 22‐day period of offshore bar migration at Egmond, Netherlands. With best fit parameter values the modeled temporal evolution of the cross‐shore bed profiles agrees well with the observations. Model skill, defined as 1 minus the ratio of prediction to no‐change error variances, ranges from 0.50 at Egmond to 0.88 for the prolonged onshore bar migration at Duck. Localized (in time and space) reductions in model skill coincide with alongshore variations in the observed morphology. Consistent with earlier observations, simulated offshore bar migration takes place during storms when large waves break on the bar and is due to the feedback between waves, undertow, suspended sediment transport, and the sandbar. Simulated onshore bar migration is predicted for energetic, weakly to nonbreaking conditions and is due to the feedback between near‐bed wave skewness, bedload transport, and the sandbar, with negligible to small effects of bound infragravity waves and near‐bed streaming. Under small waves and conditions, when breaking and nonbreaking conditions alternate with the tide, the sandbar is predicted to remain stationary. The intersite differences in the optimum parameter values are, at least partly, induced by insensitivity to parameter variations, parameter interdependence, and errors in the offshore wave forcing.
Intermediate water links to Deep Western Boundary Current variability in the subtropical NW Atlantic during marine isotope stages 5 and 4
Authors: Evans H. K. , Hall I. R. , Bianchi G. G. , Oppo D. W.
Published: August 2007

Records from Ocean Drilling Program Sites 1057 and 1059 (2584 m and 2985 m water depth, respectively) have been used to reconstruct the behavior of the Deep Western Boundary Current (DWBC) on the Blake Outer Ridge (BOR) from 130 to 60 kyr B.P. (marine isotope stage (MIS) 5 and the 5/4 transition). Site 1057 lies within Labrador Sea Water (LSW) but close to the present‐day boundary with Lower North Atlantic Deep Water (LNADW), while Site 1059 lies within LNADW. High‐resolution sortable silt mean () grain size and benthic δ13C records were obtained, and changes in the DWBC intensity and spatial variability were inferred. Comparisons are made with similar proxy records generated for the Holocene from equivalent depth cores on the BOR. During MIS 5e, evidence at Site 1057 suggests slower relative flow speeds consistent with a weakening and a possible shoaling of the LSW‐sourced shallower limb of the DWBC that occupies these depths today. In contrast, the paleocurrent record from the deeper site suggests that the fast flowing deep core of the DWBC was located close to its modern depth below 3500 m. During this interval the benthic δ13C suggests little chemical stratification of the water column and the presence of a near‐uniform LNADW‐dominated water mass. After ∼111 kyr B.P. the record at Site 1057 increases to reach values similar to Site 1059 for the rest of MIS 5. The strengthening of flow speeds at the shallow site may correspond to the initiation of Glacial North Atlantic Intermediate Water formation also suggested by a divergence in the benthic δ13C records with Site 1057 values increasing to ∼1.2‰. Coupled suborbital oscillations in DWBC flow variability and paleohydrography persisted throughout MIS 5. Comparison of these data with planktonic δ18O records from the sites and alkenone‐derived sea surface temperature (SST) estimates from the nearby Bermuda Rise suggest a hitherto unrecognized degree of linkage between oscillations in subtropical North Atlantic SST and DWBC flow.
Volcanism in a compressional Andean setting: A structural and geochronological study of Tromen volcano (Neuquén province, Argentina)
Authors: Galland Olivier , Hallot Erwan , Cobbold Peter R. , Ruffet Gilles , de Bremond d'Ars Jean
Published: August 2007

We document evidence for growth of an active volcano in a compressional Andean setting. Our data are surface structures and 39Ar‐40Ar ages of volcanic products on Tromen volcano. Tromen is an active back‐arc volcano in the Andean foothills of Neuquén province, Argentina. Its volcanic products are unconformable upon Mesozoic strata of the Neuquén basin. The volcano straddles a N‐S trending pop‐up, which formed during E‐W shortening. The main underlying structures are eastward verging thrusts. Their traces curve around the eastern foot of the volcano. Minor folds and faults also occur in the volcanic cover of Tromen, as a result of E‐W shortening. New 39Ar‐40Ar ages for these volcanic rocks are younger than 2.27 ± 0.10 Ma and show that Tromen has been active almost continuously from the late Pliocene to the Holocene. We conclude that volcanism and thrusting have been coeval and that magma must have reached the surface in a tectonic setting of horizontal compression. Our results have wider implications for magmatic processes in such settings.
Validation of ionospheric weather predicted by Global Assimilation of Ionospheric Measurements (GAIM) models
Authors: Decker Dwight T. , McNamara Leo F.
Published: August 2007

The ability of the Utah State University (USU) Global Assimilation of Ionospheric Measurements (GAIM) model to specify the day‐to‐day variability of the ionosphere is assessed by comparison of specified hourly values of foF2 with observations that were not assimilated by the model. If the specifications are to be an improvement over a climatological model with zero average error, the interdecile width of errors of the specifications at each hour must be less than the interdecile width of the observations. It has been found that the median specified values of foF2 for undisturbed days are quite accurate, and that the interdecile width of errors of the specifications is less than that of the observations most of the time for midlatitude sites, provided there is a GPS TEC site sufficiently close to the ionosonde site. The errors in GAIM values of foF2 for Australian locations tend to be larger for larger distances from a GPS site, and for low latitudes. GAIM also tracks the values of foF2 on disturbed days, but tends to be conservative, not reproducing the full extent of the departures of the disturbed values from the background values.
Blood—Brain Barrier Genomics and Cloning of a Novel Organic Anion Transporter
Authors: Chu Chun , Li Jian Yi , Boado Ruben J , Pardridge William M
Published: August 2007

A novel organic anion transporter selectively expressed at the blood—brain barrier (BBB), originally designated BBB-specific anion transporter type 1 (BSAT1), and now classified as Slco1c1, has been cloned from a BBB genomics program as a partial cDNA; this study describes the cloning and expression of the full-length cDNA from a rat brain capillary cDNA library. Northern analysis revealed the selective expression of the transporter at the BBB, and the transporter was expressed after permanent transfection of human 293 cells with cDNA encoding either the full length or open reading frame mRNA. The full-length transporter cDNA was 2.6 kb, and the mRNA was highly expressed at the rat brain microvasculature, but not in kidney, liver, heart, or lung, or in glial cells or brain glial tumors. Blood—brain barrier-specific anion transporter type 1 expression in 293 cells was poor after the transfection of the full-length cDNA, whereas transporter expression in 293 cells was high after transfection of the open reading frame. The transporter showed asymmetric kinetic properties in comparison of the influx and efflux of model substrates, thyroxine (T4), triiodothyronine (T3), and estradiol-glucuronide (E2G). Thyroxine and T3 inhibited the influx of E2G, but E2G did not inhibit thyroxine influx, and T3 only weakly inhibited the influx of T4. Extracellular E2G stimulated the transefflux of intracellular T4. Blood—brain barrier-specific anion transporter type 1 is a novel organic anion transporter that is a sodium-independent exchanger that may participate in the active efflux of iodothyronines and steroid conjugates at the BBB.
The effects of smoking on bone health
Authors: Wong Peter K. K. , Christie Jemma J. , Wark John D.
Published: August 2007

Osteoporotic fractures are a major public health problem in most developed countries and an increasing concern in much of the developing world. This healthcare burden will increase significantly worldwide over the next 20 years due to aging of the population. Smoking is a key lifestyle risk factor for bone loss and fractures that appears to be independent of other risk factors for fracture such as age, weight, sex and menopausal status. This review discusses the effects of smoking on bone health in pre-menopausal and post-menopausal women and men. Data from twin studies and the three main published meta-analyses are presented. Possible mechanisms by which smoking affects bone mass are reviewed. Despite smoking being a major lifestyle risk factor for osteoporosis, the mechanisms underlying smoking-associated bone loss and fracture risk remain poorly understood. The effect appears dose-dependent, and may be, at least partially, reversible. However, more work is required to confirm and characterize the reversibility of smoking-associated bone defects. Finally, strategies for quitting smoking are discussed. Encouragement of lifestyle alterations, including smoking cessation, should be a major component of any bone therapeutic programme.
The α-adducin Gly460Trp polymorphism and the antihypertensive effects of exercise among men with high blood pressure
Authors: Pescatello Linda S. , Blanchard Bruce E. , Tsongalis Gregory J. , Maresh Carl M. , O'Connell Ann , Thompson Paul D.
Published: August 2007

The α-adducin Gly460Trp polymorphism alters renal sodium transport and is associated with hypertension. Despite the immediate sodium- and volume-depleting effects of aerobic exercise, the influence of the α-adducin Gly460Trp polymorphism on PEH (postexercise hypotension) has not been studied. In the present study we examined the effects of the α-adducin Gly460Trp polymorphism on PEH among 48 men (42.6±1.6 years; mean±S.E.M.) with high BP (blood pressure; 144.0±1.7/84.7±1.1 mmHg). Subjects completed three experiments: non-exercise control and two cycle exercise sessions at 40% (light exercise) and 60% (moderate exercise) of maximal oxygen consumption. Subjects left the laboratory wearing an ambulatory BP monitor. PCR and restriction enzyme digestion determined the genotypes. No subjects had the Trp460Trp genotype due to the low frequency of 5% in the population. Repeated measure ANCOVA tested whether BP differed over time between experimental conditions and genotypes (Gly460Gly, n=36; Gly460Trp, n=12). Among Gly460Gly genotypes, SBP (systolic BP) was reduced by 5.2±1.4 mmHg after moderate exercise compared with non-exercise controls over 9 h (P<0.01). Among Gly460Trp genotypes, SBP was lowered by 7.8±2.3 mmHg; after light exercise compared with non-exercise controls over 9 h (P<0.05). The SBP reductions after light exercise (0.6±1.3 compared with 7.8±2.3 mmHg; P<0.05) but not moderate exercise (5.2±1.4 compared with 3.8±2.4 mmHg; P≥0.05) differed between the Gly460Gly and Gly460Trp genotypes respectively. Men with Gly460Gly had a reduced SBP after moderate exercise, whereas men with Gly460Trp had a reduced SBP after light exercise. However, only the SBP reductions after light exercise differed between genotypes. Our findings indicate that the α-adducin Gly460Trp genotype may be useful in identifying men who have a reduced BP after lower intensity aerobic exercise.
Inspiratory muscle strength in chronic obstructive pulmonary disease depending on disease severity
Authors: Kabitz Hans-Joachim , Walterspacher Stephan , Walker David , Windisch Wolfram
Published: August 2007

Staging criteria for COPD (chronic obstructive pulmonary disease) include symptoms and lung function parameters, but the role of reduced inspiratory muscle strength related to disease severity remains unclear. Therefore the present study tested whether inspiratory muscle strength is reduced in COPD and is related to disease severity according to GOLD (Global Initiative for Chronic Obstructive Lung Disease) criteria and assessed its clinical impact. PImax (maximal inspiratory mouth occlusion pressure), SnPna (sniff nasal pressure) and TwPmo (twitch mouth pressure) following bilateral anterior magnetic phrenic nerve stimulation were assessed in 33 COPD patients (8 GOLD0, 6 GOLDI, 6 GOLDII, 7 GOLDIII and 6 GOLDIV) and in 28 matched controls. Furthermore, all participants performed a standardized 6 min walking test. In comparison with controls, PImax (11.6±2.5 compared with 7.3±3.0 kPa; P<0.001), SnPna (9.7±2.5 compared with 6.9±3.3 kPa; P<0.001) and TwPmo (1.6±0.6 compared with 0.8±0.4 kPa; P<0.001) were markedly lower in COPD patients. TwPmo decreased with increasing COPD stage. TwPmo was correlated with walking distance (r=0.75; P<0.001), dyspnoea (r=−0.61; P<0.001) and blood gas values following exercise (r>0.57; P<0.001). Inspiratory muscle strength, as reliably assessed by TwPmo, decreased with increasing severity of COPD and should be considered as an important factor in rating disease severity and to reflect burden in COPD.
Abnormal regional myocardial deformation properties and increased aortic stiffness in normotensive patients with aortic coarctation despite successful correction: an ABPM, standard echocardiography and strain rate imaging study
Authors: di Salvo Giovanni , Pacileo Giuseppe , Limongelli Giuseppe , Verrengia Marina , Rea Alessandra , Santoro Giuseppe , Gala Simona , Castaldi Biagio , D'andrea Antonello , Caso Pio , Giovanna Russo Maria , Calabró Raffaele
Published: August 2007

The long-term follow-up data subsequent to a successful repair of AoC (aortic coarctation) show that life expectancy remains reduced. Previous standard echocardiographic studies have demonstrated normal or increased systolic cardiac function in patients following successful repair of AoC. SR (strain rate) imaging is a new technique able to detect subclinical myocardial abnormalities. In the present study we investigated whether young patients (without hypertension, as assessed using ambulatory blood pressure monitoring and an exercise test) following successful AoC repair already have abnormal myocardial deformation properties, and the relationship of the deformation properties with aortic stiffness. We studied 166 subjects, 83 AoC non-hypertensive patients (mean age 12±4 years) a number of years after successful repair of AoC and 83 age- and sex-matched subjects as controls. Peak systolic SR (1/s) for both regional longitudinal and radial function was assessed. The aortic stiffness index was calculated from the echocardiographically derived thoracic aortic diameters, and the measurement of blood pressure was obtained by cuff sphygmomanometry. The LV (left ventricular) ejection fraction was significantly increased in AoC patients, whereas regional longitudinal SRs were significantly reduced (−1.1±0.9 compared with −2±0.5, P<0.0001) in patients. The aortic stiffness index was significantly increased in AoC patients (12±9, P<0.0001). At multilinear regression analysis, age at repair (P=0.005; coefficient, −0.201; S.E.M., 0.027) and the aortic stiffness index (P=0.0029; coefficient, 0.334; S.E.M., 0.423) predicted longitudinal SR. Despite the presence of a successful repair for AoC, in the absence of hypertension, longitudinal deformation properties were significantly impaired. Moreover, the degree of longitudinal SR impairment was correlated with age at repair and aortic stiffness. Early repair can delay the onset of hypertension in postcoarctectomy patients, but cannot prevent the innate structural and functional abnormalities of the aorta and their deleterious effect on myocardial deformation properties.
Mechanisms underlying the role of glucocorticoids in the early life programming of adult disease
Authors: Drake Amanda J. , Tang Justin I. , Nyirenda Moffat J.
Published: August 2007

Compelling epidemiological evidence suggests that exposure to an adverse intrauterine environment, manifested by low-birth weight, is associated with cardiometabolic and behavioural disorders in adulthood. These observations have led to the concept of ‘fetal programming’. The molecular mechanisms that underlie this relationship remain unclear, but are being extensively investigated using a number of experimental models. One major hypothesis for early life physiological programming implicates fetal overexposure to stress (glucocorticoid) hormones. Several animal studies have shown that prenatal glucocorticoid excess, either from endogenous overproduction with maternal stress or through exogenous administration to the mother or fetus, reduces birth weight and causes lifelong hypertension, hyperglycaemia and behavioural abnormality in the offspring. Intriguingly, these effects are transmitted across generations without further exposure to glucocorticoids, which suggests an epigenetic mechanism. These animal observations could have huge implications if extrapolated to humans, where glucocorticoids have extensive therapeutic use in obstetric and neonatal practice.
Improved quasi-unary nucleation model for binary H2SO4–H2O homogeneous nucleation
Authors: Yu Fangqun
Published: August 2007

Aerosol nucleation events have been observed at a variety of locations worldwide, and may have significant climatic and health implications. Binary homogeneous nucleation (BHN) of H2SO4 and H2O is the foundation of recently proposed nucleation mechanisms involving additional species such as ammonia, ions, and organic compounds, and it may dominate atmospheric nucleation under certain conditions. We have shown in previous work that H2SO4–H2O BHN can be treated as a quasi-unary nucleation (QUN) process involving H2SO4 in equilibrium with H2O vapor, and we have developed a self-consistent kinetic model for H2SO4–H2O nucleation. Here, the QUN approach is improved, and an analytical expression yielding H2SO4–H2O QUN rates is derived. Two independent measurements related to monomer hydration are used to constrain the equilibrium constants for this process, which reduces a major source of uncertainty. It is also shown that the capillarity approximation may lead to a large error in the calculated Gibbs free energy change for the evaporation of H2SO4 molecules from small H2SO4–H2O clusters, which affects the accuracy of predicted BHN nucleation rates. The improved QUN model—taking into account the recently measured energetics of small clusters—is thermodynamically more robust. Moreover, predicted QUN nucleation rates are in better agreement with available experimental data than rates calculated using classical H2SO4–H2O BHN theory.
Interaction of vortex wakes and buoyant jets: A study of two-dimensional dynamics
Authors: Shirgaonkar Anup A. , Lele Sanjiva K.
Published: August 2007

The dynamics of aircraft wakes are affected by buoyancy forces resulting from stratification and exhaust jets. In this study the influence of jet buoyancy on the descent and spacing of a trailing vortex pair is characterized using a two-dimensional model problem. Results from laminar wake-jet simulations with and without stratification are presented. In addition to the vorticity dynamics of wakes in a stratified medium reported in the existing literature, the presence of the jets causes additional mechanisms which affect the wake behavior. The two opposite-signed components of baroclinic vorticity induced by the jets result in strengthening of the primary trailing vortices and also produce an induced velocity on the primary vortices. Both of these components cause an overall reduction in the primary vortex spacing and a faster vortex wake descent. The entrainment of jet fluid into the vortex cores and detrainment into the atmosphere is illustrated. The influence of buoyancy on jet exhaust fluid transport and total circulation is investigated.
On the decay rate of the false vacuum
Authors: Zoli Marco
Published: August 2007

The finite size theory of metastability in a quartic potential is developed by the semiclassical path integral method. In the quantum regime, the relation between temperature and classical particle energy is found in terms of the first complete elliptic integral. At the sphaleron energy, the criterion which defines the extension of the quantum regime is recovered. Within the latter, the temperature effects on the fluctuation spectrum are evaluated by the functional determinant method and computation. The eigenvalue which causes metastability is determined as a function of size/temperature by solving a Lamè equation. The ground state lifetime shows remarkable deviations with respect to the result of the infinite size theory.
Low-voltage-operating complementary inverters with C60 and pentacene transistors on glass substrates
Authors: Kitamura Masatoshi , Arakawa Yasuhiko
Published: August 2007

Organic complementary inverters with C60 and pentacene thin-film transistors (TFTs) have been fabricated on glass substrate. The inverter operated at low voltages of 1–5V. The C60 and pentacene TFTs had high field-effect mobilities of 0.68 and 0.59cm2∕Vs, and threshold voltage of 0.80 and −0.84V, respectively. The low threshold voltage enables the low voltage operation of the inverter.
Low-temperature conductive tip atomic force microscope for carbon nanotube probing and manipulation
Authors: Prior M. , Makarovski A. , Finkelstein G.
Published: August 2007

The authors describe conductive tip atomic force microscope used for imaging carbon nanotubes at low temperatures. The instrument allows them to measure the tip-nanotube conductance while performing the topographic scan of the nanotubes on a nonconductive SiO2 substrate. For nanotubes weakly coupled to the contacting electrode, they observe the Coulomb blockade pattern in the tip-nanotube conductance. They reversibly modified the conductance pattern by applying the tip pressure.
7.8-GHz flexible thin-film transistors on a low-temperature plastic substrate
Authors: Yuan Hao-Chih , Celler George K. , Ma Zhenqiang
Published: August 2007

RF flexible thin-film transistors (TFTs) with a new speed record of cut-off frequency (fT) of 2.04 GHz and maximum oscillation frequency (fmax) of 7.8 GHz were realized using single-crystal Si nanomembrane as an active channel layer on a low-temperature plastic substrate. We report the detailed device layout design considerations for optimizing the frequency response of the flexible RF TFTs, supported by accurate small-signal equivalent circuit modeling. It is indicated that, by properly considering the tradeoff between the parasitic source/drain resistances and the parasitic source-to-gate/drain-to-gate capacitances, fT and fmax of the single-crystal-Si TFTs can be optimized separately in order to meet the requirements of certain potential RF applications.
Interdot coupling in a Si-based coupled double dot system for spin qubit gate
Authors: Shin S. J. , Lee J. J. , Chung R. S. , Kim M. S. , Park E. S. , Choi J. B. , Kim N. S. , Park K. H. , Lee S. D. , Kim N. , Kim J. H.
Published: August 2007

A Si-based coupled double dot has been studied for its application to two-qubit gate. The authors manipulated electron number of each dot by using its adjacent side gate and finally observed a honeycomb charge-stability pattern, demonstrating interdot capacitive coupling. From the honeycomb diagram the capacitance-related interdot coupling parameters were extracted. Moreover, a fine structure in a conductance trace near the triple point of the honeycomb, where the tunnel coupling is maximized, was measured for finite bias, and its dependence on the interdot coupling was attributed to the spin exchange between the two dots.
Rheological properties of Pb, Sb, Bi, and Sn melts
Authors: Sun Chunjing , Geng Haoran , Ji Leilei , Wang Yan , Wang Guizhen
Published: August 2007

The rheological properties of metal Pb, Sb, Bi, and Sn melts were investigated using a coaxial cylinder high-temperature viscometer. The results show that the torque value decreases with increasing temperature, which is consistent with the temperature dependence of their viscosity. The relationship between the torque and rotational rate of the Sb and Pb melt exhibits a linear change in the measured temperature range, but that of the Bi and Sn melts shows an obvious non-Newtonian characteristic in the low-temperature range and at relatively high shear stress. The rheological characteristics of the melts were correlated with the evolution of microstructure. The discussion was made in detail.
Preparation and thermoelectric properties of heavily Nb-doped SrO(SrTiO3)1 epitaxial films
Authors: Lee Kyu Hyoung , Ishizaki Akihiro , Kim Sung Wng , Ohta Hiromichi , Koumoto Kunihito
Published: August 2007

We report the epitaxial film growth, by pulsed laser deposition, of c-axis-oriented Nb-doped SrO(SrTiO3)1 films having a K2NiF4-type structure and their thermoelectric properties over a wide temperature range, from 20 to 800 K. High-resolution x-ray diffraction and reflection high energy electron diffraction patterns revealed that the films were grown heteroepitaxially on the (001) face of the LaAlO3 substrate. The thermoelectric properties of the Nb-doped SrO(SrTiO3)1 epitaxial films were improved in terms of power factor compared to those for polycrystalline Nb-doped SrO(SrTiO3)1. A theoretical analysis of the transport parameters revealed that the intrinsic transport occurred predominantly in the SrTiO3 layers.
Spontaneous emission lifetime distribution of infinite line antennas in two-dimensional photonic crystals with finite size
Authors: Xu Xingsheng , Wang Yiquan
Published: August 2007

The authors calculate the lifetime distribution functions of spontaneous emission from infinite line antennas embedded in two-dimensional disordered photonic crystals with finite size. The calculations indicate the coexistence of both accelerated and inhibited decay processes in disordered photonic crystals with finite size. The decay behavior of the spontaneous emission from infinite line antennas changes significantly by varying factors such as the line antennas’ positions in the disordered photonic crystal, the shape of the crystal, the filling fraction, and the dielectric constant. Moreover, the authors analyze the effect of the degree of disorder on spontaneous emission.
Quantification of free volume differences in a Zr44Ti11Ni10Cu10Be25 bulk amorphous alloy
Authors: Launey M. E. , Kruzic J. J. , Li C. , Busch R.
Published: August 2007

Deformation of metallic glasses requires the existence of free volume to allow atomic movement under mechanical loading. Accordingly, quantification of the free volume state of the alloy is crucial to understand its mechanical behavior. By annealing below the glass transition temperature, the free volume of a Zr44Ti11Ni10Cu10Be25 bulk metallic glass was varied via structural relaxation. Differential scanning calorimetry was used to quantify enthalpy differences between the relaxed and as-cast materials, which were then quantitatively related to average free volume differences. These results can be used to characterize the average free volume in this alloy for future mechanical property studies.
Single electron pumping in InAs nanowire double quantum dots
Authors: Fuhrer A. , Fasth C. , Samuelson L.
Published: August 2007

Closely spaced local gate electrodes are used to electrically define a double quantum dot along an InAs nanowire crystal. By applying a periodic pulse sequence to two plunger gate electrodes controlling the double quantum dot charge configuration, the device is operated as a single electron pump. The authors find that within measurement accuracy, the pumping current equals one electron per cycle for frequencies up to 2MHz, demonstrating the suitability of nanowire based quantum dots for pumping applications.
Low resistivity Ga-doped ZnO thin films of less than 100nm thickness prepared by ion plating with direct current arc discharge
Authors: Yamada Takahiro , Miyake Aki , Kishimoto Seiichi , Makino Hisao , Yamamoto Naoki , Yamamoto Tetsuya
Published: August 2007

Low resistivity Ga-doped ZnO films were prepared on a glass substrate by ion plating with direct current arc discharge. Thickness dependent changes in the electrical properties of the films are reported, focusing on the thin films of less than 100nm thickness. Structural analyses showed that the thinnest film of 30nm thickness consists of well-oriented columnar grains normal to the substrate, and the resistivity was as low as 4.4×10−4Ωcm. The changes in lattice strain and c-axis fluctuation with the growth of grains are also shown to be associated with the electrical properties.
Does the wall number of carbon nanotubes matter as conductive transparent material?
Authors: Li Zhongrui , Kandel Hom R. , Dervishi Enkeleda , Saini Viney , Biris Alexandru S. , Biris Alexandru R. , Lupu Dan
Published: August 2007

As electrically conductive and optically transparent thin coating material, double-wall carbon nanotube network was found to have better transparency-conductance performance as compared with single-wall carbon nanotube (SWNT) and multiwall carbon nanotube (MWNT). The electronic transportability and optical properties of the SWNT films can be altered by chemical modification of thionyl chloride. Additionally, the conductance-temperature dependence analysis revealed that variable-range hopping mechanism dominates the conductance of few wall nanotube mats while fluctuation-assisted tunneling plays a more important role in that of MWNT films.
Observation of Kastler ring stimulated emission from an organic microcavity
Authors: Schneeweiss P. , Sudzius M. , Gehlhaar R. , Hoffmann M. , Lyssenko V. G. , Fröb H. , Leo K.
Published: August 2007

The authors report the observation of an intense conical emission from an organic microcavity. The emission is characterized experimentally and modeled as a higher order Fabry-Perot mode predicted 45years ago by Kastler [Appl. Opt. 1, 17 (1962)]. A distinct cone is only visible above the normal mode laser threshold which implies a stimulated emission nature of the off-axial light. The input/output characteristics of normal and cone emissions hint that both originate from one and the same lasing mode.
Wideband quarter-wave liquid crystal cell with wide viewing angle for the reflective mode with single polarizer
Authors: Ko Tae Woon , Kim Jae Chang , Choi Hyun Chul , Park Kyoung-Ho , Lee Seung Hee , Kim Kyung-Mi , Lee Wa-Ryong , Lee Gi-Dong
Published: August 2007

In this letter, the authors propose an optical configuration for the reflective liquid crystal (LC) cell with single polarizer, which can show the wideband property for high contrast in oblique incidence. The cell consists of a biaxial, a half-wave retarder, a quarter-wave LC cell, and a positive C plate in addition to a reflector. They optimize the configuration of the reflective LC cell on the Poincaré sphere using trigonometric calculation. In order to verify the optical performance, the authors experimentally compare the optical characteristics of the proposed LC cell with those of the conventional LC cell.
Pulse height reduction effects of superconducting tunnel junction particle detectors for low-energy light molecular ions
Authors: Tomita S. , Sato Y. , Ohkubo M. , Ukibe M. , Hayakawa S.
Published: August 2007

The performance of particle detectors using superconducting tunnel junctions has been studied for metal cluster or molecular ions accelerated at 3keV. The output pulse height for individual ion impact decreases as the mass of projectiles increases in a mass range of less than 800amu. In addition, pulse height reduction effects strongly depend on the molecular species. These phenomena are understood by taking into account secondary electron emission that carries part of the deposited kinetic energies of ion away from the junction surface.
Combined Raman study of InGaAsN from the N-impurity and InGaAs-matrix sides
Authors: Chafi A. , Pagès O. , Postnikov A. V. , Gleize J. , Sallet V. , Rzepka E. , Li L. H. , Jusserand B. , Harmand J. C.
Published: August 2007

The authors report a Raman study of In0.08Ga0.92As0.98N0.02 covering both N- and InGaAs-related spectral ranges, supported by ab initio and phenomenological modeling of the spectra. The authors argue that the crystal self-organizes at different scales to reduce the N-induced strain. Locally, this is achieved by In-N-Ga3 configurations, as is well known. Moreover, a long scale organization occurs in the InGaAs matrix, away from N. This is apparent in the over representation of the “short” Ga–As bonds from the In-rich region, as compared with random InGaAs. Quantitative insight is derived at the mesoscopic scale from the 1-bond→2-phonon “percolation”-type behavior of the dominant Ga–As species.
Modified atomic layer deposition of RuO2 thin films for capacitor electrodes
Authors: Kim Jin-Hyock , Kil Deok-Sin , Yeom Seung-Jin , Roh Jae-Sung , Kwak Noh-Jung , Kim Jin-Woong
Published: August 2007

The authors investigated the modified atomic layer deposition (ALD) of RuO2 films using bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] at a deposition temperature of 265°C. Oxygen gas diluted with argon was supplied throughout all of the ALD steps. The growth rate of the modified ALD RuO2 was about 1.4Å∕cycle, which is higher than that of conventional Ru ALD due to the increase in the amount of Ru(EtCp)2 adsorption per cycle, as well as the difference in the unit cell volumes of Ru and RuO2. The film thickness increased linearly with the number of cycles, and the incubation cycle in the initial stage was negligible.
Comparing Monte Carlo simulation and pseudospectral time-domain numerical solutions of Maxwell’s equations of light scattering by a macroscopic random medium
Authors: Tseng Snow H. , Huang Boyeh
Published: August 2007

The Monte Carlo simulation of light scattering by a cluster of dielectric spheres is compared with numerical solutions of Maxwell’s equations via the pseudospectral time-domain technique. By calculating the total scattering cross-section (TSCS) spectrum, respectively, the spectral light scattering characteristics are determined. Since the Monte Carlo simulation falls short to accurately account for coherent interference effects, it is shown that the Monte Carlo simulation yields TSCS spectra that significantly deviate from the numerical solutions of Maxwell’s equations. Therefore, it is necessary to resort to Maxwell’s equations in order to accurately determine the light scattering characteristics of a macroscopic geometry.
Optical and magnetic behavior of erbium-doped GaN epilayers grown by metal-organic chemical vapor deposition
Authors: Zavada J. M. , Nepal N. , Ugolini C. , Lin J. Y. , Jiang H. X. , Davies R. , Hite J. , Abernathy C. R. , Pearton S. J. , Brown E. E. , Hömmerich U.
Published: August 2007

The authors report on the optical and magnetic properties of GaN epilayers, grown by metal-organic chemical vapor deposition, with in situ Er doping at concentrations up to ∼1021cm−3. Using ultraviolet laser excitation, all samples exhibited photoluminescence near 1540nm with the integrated intensity approximately proportional to the Er concentration. Data from superconducting quantum interference device measurements indicated room temperature ferromagnetic ordering in all Er-doped GaN epilayers. The saturation magnetization in these samples also followed a nearly linear fit to the Er concentration. X-ray diffraction spectra did not reveal evidence of any second phases over this range of Er concentrations.
Saudi Arabia sets up research university
Authors: Feder Toni
Published: August 2007

The King Abdullah University of Science and Technology aims to become a world-class institution.
Graphene: Exploring carbon flatland
Authors: Geim Andrey K. , MacDonald Allan H.
Published: August 2007

Just one atom thick, this two-dimensional semiconductor does not resemble any known material.
Black holes and their environments
Authors: Miller Jon M. , Reynolds Christopher S.
Published: August 2007

Local spacetime geometry is not the only thing that black holes affect. They also profoundly influence galaxy formation and have an impact on scales as large as clusters of galaxies.