bluuebunny/crossref_metadata_2025_split huggingface dataset:
New phenomena of mixed breakdown in silicon
Authors: Lee C. I. , Ngo V. H. , Pan D. S. 
Published: February 2006

AbstractA new theory is briefly presented to explain our recently observed anomalous phenomena in the mixed breakdown regime of two silicon diodes. The multiplication coefficients have larFge values at very small reverse biased voltage, first decrease with increasing bias and then drastically increase again. In the theory, both thermally generated carriers and different types of interband tunneling carriers are all included in initiating the impact ionization processes, each with a different dead space. The theory is expected to be a good approximation when the carrier distribution function is determined primarily by phonon scattering and impurity scattering. The anomalous trend in the newly observed multiplication coefficients can be well explained by the theory. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Size‐dependent elastic interaction between a screw dislocation and a circular nano‐hole with surface stress
Authors: Fang Q. H. , Liu Y. W. 
Published: February 2006

AbstractThe effect of surface stress on the size‐dependent interaction of a screw dislocation with a circular nano‐hole under remote antiplane shear loads is examined. By using the complex variable method, the analytical expressions of the complex potential in infinite matrix and the image force acting on the screw dislocation are obtained. The associated solutions to the problem of a screw dislocation interacting with a nano‐inhomogeneity are also given. The results show that the influence of the surface stress on the motion of the dislocation near the hole becomes remarkable when the size of the hole is reduced to nanometer scale, leading to that the normalized image force depends on the hole size which differs from the size‐independent classical elastic solution. Our results are helpful in the understanding of the motion mechanism of the dislocation and relevant physical phenomena in nano‐structured materials. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Trend, variability or extreme event? The importance of long‐term perspectives in river ecology
Authors: Reid Michael A. , Ogden Ralph W. 
Published: February 2006

AbstractTemporal variability at extra‐annual scales is typically a feature of freshwater ecosystems, particularly in places like Australia where the climate is highly unpredictable and where recent anthropogenic changes have been dramatic. Accounting for this variability when studying freshwater systems is generally not possible if freshwater ecologists rely solely on measurements carried out in the course of studies that rarely exceed a few years in length. Alternative methods can be used to extend temporal perspective; however, we argue these are under‐utilised in river ecology. This paper outlines approaches for extending temporal perspective (historical studies, palaeolimnological studies and modelling) and illustrates, using pertinent examples, areas of river ecology where we believe they can be of particular use. We conclude with some suggestions for ways in which cooperation between relevant disciplines can be enhanced. Copyright © 2006 John Wiley & Sons, Ltd.
Flow variability in dryland rivers: boom, bust and the bits in between
Authors: Bunn Stuart E. , Thoms Martin C. , Hamilton Stephen K. , Capon Samantha J. 
Published: February 2006

AbstractAustralian dryland rivers are acknowledged as being among the most variable and unpredictable in the world in terms of their flow regimes. Although renowned for their spectacular floods over vast and complex floodplains, rivers exist for much of the time as discrete waterholes, which are important refugia for aquatic biota. Recent work has shown that waterholes are filled by surface flows and there is little evidence of groundwater contributions. The permanence of these refugia is largely determined by waterhole morphology and evaporative loss, and some waterholes can clearly persist for 2 years or more without surface flow connection. As a consequence, the spatial distribution of refugia for aquatic biota is determined not only by the physical template but also by the duration of dry spells and the timing of flow events. Flow variability also has a major influence on aquatic production in these systems and ultimately influences food availability for fish and other consumers. During dry spells, aquatic food webs in waterholes are largely supported by algal production in the shallow littoral zone. At the other extreme, during floods, the boom of aquatic production on floodplains provides an immense food resource. However, there are many occasions when in‐channel flows (flow pulses) result in periods where neither of these sources of production is likely to be available. Although such flow pulses are essential for the physical persistence and connectivity of waterholes, we propose that they may lead to food limitation and stress for populations of fish and other consumers. Water resource development in dryland rivers often leads to an increase in the frequency and duration of flow pulses, due to reduced floods and elevated base flows. This increase in the ‘bits in between’ natural boom or bust conditions may help to explain the observed decline in ecosystem health in dryland river systems with significant water resource development. Copyright © 2006 John Wiley & Sons, Ltd.
Variability in channel form in a free‐flowing dryland river
Authors: Beyer Patricia J. 
Published: February 2006

AbstractThis study examines channel form of the Verde River system in order to explain system fragmentation. Morphologic analyses draw from discharge and shear stress calculations generated by modelling the flow through 14 surveyed cross‐sections along the Verde River, representing six river segments with distinct hydrologic and geologic characteristics. At‐a‐station and downstream hydraulic geometries for the Verde River highlight local variability in channel morphology. Modified at‐a‐station hydraulic geometry analyses using cross‐section subsection discharge and shear stress values similarly show greater variability within cross‐sections than between cross‐sections. Competence and capacity increase at a fairly uniform rate for similar features throughout the system, indicating an overall efficiency in sediment transport. Variations in channel form and associated sediment transport as represented by competence and capacity are largely related to combinations of macroscale local factors, including channel pattern, gradient, valley width, tributary inputs and human activity rather than megascale, basin‐scale or subbasin scale factors. Copyright © 2006 John Wiley & Sons, Ltd.
A Gamma-convergence argument for the blow-up of a non-local semilinear parabolic equation with Neumann boundary conditions
Authors: El Soufi A. , Jazar M. , Monneau R. 
Published: February 2006

In this paper we study a simple non-local semilinear parabolic equation in a bounded domain with Neumann boundary conditions. We obtain a global existence result for initial data whose

L^{\infty }

-norm is less than a constant depending explicitly on the geometry of the domain. A natural energy is associated to the equation and we establish a relationship between the finite-time blow up of solutions and the negativity of their energy. The proof of this result is based on a Gamma-convergence technique.

Résumé
Cet article est consacré à l'étude d'un modèle simple d'équation semi-linéaire parabolique non locale dans un domaine borné sous la condition de Neumann au bord. Nous obtenons un résultat d'existence globale pour les données initiales dont la norme infinie est majorée par une constante explicite qui dépend de la géométrie du domaine. En outre, nous associons une énergie naturelle à l'équation et établissons un lien entre l'explosion en temps fini des solutions et la négativité de leur énergie. La preuve de ce résultat est fondée sur une technique de Gamma-convergence.
Large time behavior for nonlinear higher order convection–diffusion equations
Authors: Qafsaoui Mahmoud 
Published: February 2006

We study the large time asymptotic behavior, in

L^{p}

(

1 \leq p \leq \infty

), of higher derivatives

D^{\gamma }u(t)

of solutions of the nonlinear equation

\begin{cases}
&u_{t} + \mathcal{T}u = a \cdot \mathrm{∇}^{\theta }(\psi (u))\:&&\text{on }\:\mathbb{R}^{n} \times (0,\infty ), \\
&u(0) = u_{0}∊L^{1}(\mathbb{R}^{n}), &&
\end{cases}

where the integers

n

and

θ

are bigger than or equal to

1

,

a

is a constant vector in

\mathbb{R}^{p}

with

p = \tbinom{\theta + n−1}{ n−1}= \frac{(\theta + n−1)!}{\theta !(n−1)!}

. The function

ψ

is a nonlinearity such that

\psi \in\mathcal{C}^{\theta }(\mathbb{R})

and

\psi (0) = 0

, and

\mathcal{T}

is a higher order elliptic operator with nonsmooth bounded measurable coefficients on

\mathbb{R}^{n}

. We also establish faster decay when

u_{0}\in L^{1}(\mathbb{R}^{n}) \cap L^{\infty }(\mathbb{R}^{n})

.

Résumé

Nous étudions le comportement asymptotique, dans

L^{p}

(

1 \leq p \leq \infty

), des dérivées d'ordre supérieur

D^{\gamma }u(t)

des solutions de l'équation nonlinéaire (1), où

n\in \mathbb{N}^{ \ast }

,

\theta \in \mathbb{N}^{ \ast }

et

a

est un vecteur constant de

\mathbb{R}^{p}

avec

p = \tbinom{\theta + n−1}{ n−1}

. La fonction

ψ

est nonlinéaire vérifiant

\psi \in \mathcal{C}^{\theta }(\mathbb{R})

et

\psi (0) = 0

, et

\mathcal{T}

est un opérateur elliptique d'ordre supérieur à coefficients peu réguliers dans

\mathbb{R}^{n}

. Nous étudions également le cas particulier où

u_{0}∊L^{1}(\mathbb{R}^{n}) \cap L^{\infty }(\mathbb{R}^{n})

.
\( L^{1} \) existence and uniqueness results for quasi-linear elliptic equations with nonlinear boundary conditions
Authors: Andreu F. , Igbida N. , Mazón J.M. , Toledo J. 
Published: February 2006

In this paper we study the questions of existence and uniqueness of weak and entropy solutions for equations of type

−\mathrm{div}\mathbf{a}(x,Du) + \gamma (u) \ni \phi

, posed in an open bounded subset

Ω

of

\mathbb{R}^{N}

, with nonlinear boundary conditions of the form

\mathbf{a}(x,Du) \cdot \eta + \beta (u) \ni \psi

. The nonlinear elliptic operator

\mathrm{div}\mathbf{a}(x,Du)

is modeled on the

p

-Laplacian operator

\mathrm{\Delta }_{p}(u) = \mathrm{div}(|Du|^{p−2}Du)

, with

p > 1

,

γ

and

β

are maximal monotone graphs in

\mathbb{R}^{2}

such that

0 \in \gamma (0)

and

0 \in \beta (0)

, and the data

\phi \in L^{1}(\Omega )

and

\psi \in L^{1}(\partial \Omega )

.

Résumé

Dans ce papier nous étudions les questions d'existence et d'unicité de solution faibles et entropiques pour des équations elliptiques de la forme

−\mathrm{div}\mathbf{a}(x,Du) + \gamma (u) \ni \phi

, dans un domaine borné

\Omega \subset \mathbb{R}^{N}

, avec des conditions au bord générales de la forme

\mathbf{a}(x,Du) \cdot \eta + \beta (u) \ni \psi

. L'opérateur

\mathrm{div}\mathbf{a}(x,Du)

généralise l'opérateur

p

-Laplacien

\mathrm{\Delta }_{p}(u) = \mathrm{div}(|Du|^{p−2}Du)

, avec

p > 1

,

γ

et

β

sont des graphes maximaux monotones dans

\mathbb{R}^{2}

tels que

0 \in \gamma (0) \cap \beta (0)

, et les données

ϕ

et

ψ

sont des fonctions

L^{1}

.
The effect of aortic valve replacement on plasma B‐type natriuretic peptide in patients with severe aortic stenosis — one year follow‐up
Authors: Neverdal Nils O. , Knudsen Cathrine Wold , Husebye Trygve , Vengen Øystein A. , Pepper John , Lie Mons , Tønnessen Theis 
Published: February 2006

AbstractBackground:B‐type natriuretic peptide (BNP) is synthesized in cardiac tissue in response to increased wall stress and myocardial hypertrophy.Aims:In patients with severe aortic stenosis (AS) we examined the effect of aortic valve replacement (AVR) on plasma BNP and association between BNP and left ventricular mass index (LVMI) preoperatively and in the reverse‐remodeling phase twelve months postoperatively. We also examined the correlation between BNP and NYHA‐class and between BNP and age.Methods and Results:Plasma BNP analyses and echocardiographic measurements were performed preoperatively, before discharge after AVR, and at twelve months in twenty‐two patients. BNP was additionally measured at six months. Preoperatively, BNP was 283±45 pg/ml (mean±SEM). Following an immediate postoperative increase (441±38 pg/ml), BNP values decreased towards normal values at six and twelve months (139±25 and 130±18 pg/ml, respectively). LVMI was 206.5±15.8 g/m2 preoperatively and decreased to 119.7±7.2 g/m2 at twelve months with a correlation between LVMI and BNP preoperatively only (r=0.45, p<0.05). There was no correlation between BNP and NYHA‐class, whereas BNP correlated to age both pre‐ and post‐operatively.Conclusion:We report an increase in plasma BNP in patients with AS. Following a further transient increase postoperatively, BNP levels decreased at six and twelve months after AVR. BNP correlated with LVMI preoperatively, and with age both preoperatively and at twelve months.
The effects of static muscular contraction on blood pressure, heart rate, pain ratings and pressure pain thresholds in healthy individuals and patients with fibromyalgia
Authors: Kadetoff Diana , Kosek Eva 
Published: February 2006

AbstractAberrations of cardiovascular regulation and dysfunction of endogenous pain modulation have been reported in fibromyalgia (FM) patients. This study aimed at investigating the interactions between cardiovascular regulation and pain perception during static muscle contractions. Seventeen FM patients and 17 healthy controls performed a standardised static contraction (m. quadriceps femoris dx) until exhaustion. Blood pressure (BP), heart rate (HR), ratings of exertion/fatigue and pain intensity as well as pressure pain thresholds (PPTs) (at m. quadriceps dx and m. deltoideus dx) were assessed before, during and 15 min following contraction. Systolic and diastolic BP increased during contraction (p < 0.001) and decreased following contraction (p < 0.001) in both groups alike. A significant increase in HR was seen during contraction in FM patients (p < 0.001), but not in healthy controls (difference between groups p < 0.02). The rated exertion/fatigue and pain intensity increased more during contraction and remained elevated longer following contraction in the patient group. PPTs were lower in patients compared to controls at both sites at all times (p < 0.001). No group differences in PPT changes over time were found. In conclusion, no indication of an attenuated cardiovascular response to exercise was found in our FM patients. The more pronounced HR increase in patients during contraction was most likely due to deconditioning. No exercise related change in PPTs was seen in either group, most likely due to insufficient exercise intensity, but the contraction induced pain was more pronounced in the FM patients.
Estimated N leaching losses for organic and conventional farming in Denmark
Authors: TRYDEMAN KNUDSEN MARIE , SILLEBAK KRISTENSEN IB , BERNTSEN JØRGEN , MOLT PETERSEN BJØRN , STEEN KRISTENSEN ERIK 
Published: February 2006

The impact of organic, compared with conventional, farming practices on N leaching loss was studied for Danish mixed dairy and arable farms using an N balance approach based on representative data. On mixed dairy farms, a simple N balance method was used to estimate N surplus and N leaching loss. On arable farms, the simple N balance method was unreliable due to changes in the soil N pool. Consequently, the Farm ASSEssment Tool (FASSET) simulation model was used to estimate N surplus, N leaching loss and the changes in the soil N pool.The study found a lower N leaching loss from organic than conventional mixed dairy farms, primarily due to lower N inputs. On organic arable farms, the soil N pool increased over time but the N leaching loss was comparable with conventional arable farms. The soil N pool was increased primarily by organic farming practices and incorporation of straw. The highest increase in the soil N pool was seen on soils with a low initial level of organic matter. The N leaching loss was dependent on soil type, the use of catch crops and the level of soil organic matter, whereas incorporation of straw had a minor effect. N leaching was highest on sandy soils with a high level of soil organic matter and no catch crops. The present results stress the importance of using representative data from organic and conventional farming practices in comparative studies of N leaching loss. Lack of representative data has been a major weakness of previous comparisons on N leaching losses on organic and conventional farms.
Adventures in vascular biology: a tale of two mediators
Authors: Moncada S 
Published: February 2006

I would like to thank the Royal Society for inviting me to deliver the Croonian Lecture. In so doing, the Society is adding my name to a list of very distinguished scientists who, since 1738, have preceded me in this task. This is, indeed, a great honour.For most of my research career my main interest has been the understanding of the normal functioning of the blood vessel wall and the way this is affected in pathology. During this time, our knowledge of these subjects has grown to such an extent that many people now believe that the conquering of vascular disease is a real possibility in the foreseeable future.My lecture concerns the discovery of two substances, prostacyclin and nitric oxide. I would like to describe the moments of insight and some of the critical experiments that contributed significantly to the uncovering of their roles in vascular biology. The process was often adventurous, hence the title of this lecture. It is the excitement of the adventure that I would like to convey in the text that follows.
The influence of anti‐endothelial/antiphospholipid antibodies on fibrin formation and lysis on endothelial cells
Authors: Patterson Angela M. , Ford Isobel , Graham Audrey , Booth Nuala A. , Greaves Mike 
Published: February 2006

SummaryThe prothrombotic mechanisms associated with antiphospholipid antibodies remain incompletely defined. Antibody binding to endothelial cells in vitro is a feature of antiphospholipid antibody‐positive sera. We hypothesised that impairment of endothelium‐dependent fibrinolysis by antiphospholipid/anti‐endothelial antibodies is a contributory factor in the pathogenesis of thrombosis. We also aimed to confirm the displacement of annexin‐V from endothelial cells and enhanced fibrin formation. Binding of immunoglobulin (Ig) from antiphospholipid antibody‐positive sera to endothelial cells was examined using a cell‐based enzyme‐linked immunosorbent assay. Effects on fibrin formation and lysis were examined on cultured endothelial cell monolayers. Plasminogen activator inhibitor‐1 (PAI‐1) was assayed in supernatants. We confirmed antibody binding to endothelial cells. With four of 14 antiphospholipid antibody‐positive sera there was some prolongation of fibrin clot lysis time, consistent with impairment of endothelial fibrinolytic activity. Secretion of PAI‐1 was significantly correlated with clot lysis time on endothelial cell monolayers incubated with antiphospholipid/anti‐endothelial antibody‐positive sera, but not with control sera. IgG from antiphospholipid antibody‐positive sera had little effect on endothelial cell surface annexin‐V expression. We conclude that impaired endothelial fibrinolysis is a potential prothrombotic mechanism in subjects with antiphospholipid antibodies. We were unable to confirm enhanced displacement of annexin‐V from endothelium by antiphospholipid antibodies.
Flow‐substrate interactions create and mediate leaf litter resource patches in streams
Authors: HOOVER TRENT M. , RICHARDSON JOHN S. , YONEMITSU NOBORU 
Published: February 2006

Summary1. The roles that streambed geometry, channel morphology, and water velocity play in the retention and subsequent breakdown of leaf litter in small streams were examined by conducting a series of field and laboratory experiments.2. In the first experiment, conditioned red alder (Alnus rubra Bongard) leaves were released individually in three riffles and three pools in a second‐order stream. The transport distance of each leaf was measured. Several channel and streambed variables were measured at each leaf settlement location and compared with a similar number of measurements taken at regular intervals along streambed transects (‘reference locations’). Channel features (such as water depth) and substrate variables (including stone height, stone height‐to‐width ratio, and relative protrusion) were the most important factors in leaf retention.3. In the second experiment, the role of settlement location and reach type in determining the rate of leaf litter breakdown was examined by placing individual conditioned red alder leaves in exposed and sheltered locations (on the upper and lower edges of the upstream face of streambed stones, respectively) in riffle and pool habitats. After 10 days, percent mass remaining of each leaf was measured. Generally, leaves broke down faster in pools than in riffles. However, the role of exposure in breakdown rate differed between reach types (exposed pool > sheltered pool > sheltered riffle > exposed riffle).4. In the third experiment, the importance of substrate geometry on leaf litter retention was examined by individually releasing artificial leaves upstream of a series of substrate models of varying shape. Substrates with high‐angle upstream faces (were vertical or close to vertical), and that had high aspect ratios (were tall relative to their width), retained leaves more effectively.5. These results show that streambed morphology is an important factor in leaf litter retention and breakdown. Interactions between substrate and flow characteristics lead to the creation of detrital resource patchiness, and may partition leaf litter inputs between riffles and pools in streams at baseflow conditions.
The functional role of native freshwater mussels in the fluvial benthic environment
Authors: HOWARD JEANETTE K. , CUFFEY KURT M. 
Published: February 2006

Summary1. Freshwater mussels are the dominant consumer biomass in many fluvial systems. As filter feeding grazers, mussels can remove large amounts of particulate matter from the water column and transfer these resources to the substrate as biodeposits (agglutinated mussel faeces and pseudofaeces). Mussel biodeposits are a nutrient rich and easily assimilated food source and therefore may have significant relevance to benthic community structure. This study examines the functional role of Margaritifera falcata in the South Fork Eel River, California.2. We addressed two main questions: (i) Do mussels increase benthic resources in this system? (ii) If so, does this alter macroinvertebrate community structure?3. Measurements and enclosure experiments in the South Fork Eel River show that mussels can play a significant role in local food webs by increasing available fine particulate matter (both organic and inorganic) on the substrate. We document increased benthic macroinvertebrate biomass for predators and collectors (Leptophlebidae) in the presence of mussels, but only in late summer.