bluuebunny/crossref_metadata_2025 huggingface dataset:
Predictors of 10-year outcome of first-episode psychosis
Authors: White C. , Stirling J. , Hopkins R. , Morris J. , Montague L. , Tantam D. , Lewis S.
Published: February 2009

Background

Predictors of outcome for psychosis are poorly understood. Duration of untreated psychosis (DUP) appears to predict short-term outcome although its medium- to long-term role remains unclear. Neurodevelopmental indices such as pre-morbid function and/or neurological soft signs may predict longer-term outcome. We aimed to assess the impact of a range of clinical and demographic variables on long-term outcome of a geographically defined, epidemiological first-episode psychosis cohort.

Method

A 10-year follow-up was undertaken of a consecutively presenting sample of 109 cases of first-episode psychosis aged 16–50 years. Baseline assessments included positive, negative and depression symptoms, DUP, neurological soft signs and pre-morbid functioning. Multi-dimensional outcomes were assessed blind to baseline data.

Results

All participants were traced at a mean of 10.5 years post-index admission: 11 had died, 10 from non-natural causes. Of the surviving cases, 70% were comprehensively re-assessed by interview. Summary data on the remainder were collected from their family practitioner and chart review. Poor 10-year outcomes were predicted independently by poor pre-morbid functioning, baseline negative symptoms and longer DUP. The same measures, plus neurological soft signs, appeared to predict outcomes in a DSM-IV schizophrenia/schizo-affective subgroup.

Conclusions

Poor pre-morbid functioning, baseline symptoms, DUP and neurological soft signs at onset independently predict poor long-term outcome in first-episode psychosis.
Entropy production at weak Gibbs measures and a generalized variational principle
Authors: YURI MICHIKO
Published: February 2009

We consider piecewise invertible systems exhibiting intermittency and establish a generalized variational principle adapted to a non-stationary process in the following sense; the supremum is attained by non-singular (not necessarily invariant) probability measures and if the system exhibits hyperbolicity, then it reduces to the usual variational principle for the pressure. Our method relies on Ruelle’s program in the study of non-equilibrium statistical mechanics to analyze dissipative phenomena. We show non-positivity of entropy production at weak Gibbs measures and clarify when it indeed vanishes. We also discuss a generalized variational principle in the context of σ-finite invariant measures.
Convergence of diagonal ergodic averages
Authors: TOWSNER HENRY
Published: February 2009

Tao has recently proved that ifT1,…,Tlare commuting, invertible, measure-preserving transformations on a dynamical system, then for anyL∞functionsf1,…,fl, the average (1/N)∑n=0N−1∏i≤lfi∘Tinconverges in theL2norm. Tao’s proof is unusual in that it translates the problem into a more complicated statement about the combinatorics of finite spaces by using the Furstenberg correspondence ‘backwards’. In this paper, we give an ergodic proof of this theorem, essentially a translation of Tao’s argument to the ergodic setting. In order to do this, we develop two new variations on the usual Furstenberg correspondence, both of which take recurrence-type statements in one dynamical system and give equivalent statements in a different dynamical system with desirable properties.
Periodic unique beta-expansions: the Sharkovskiĭ ordering
Authors: ALLOUCHE JEAN-PAUL , CLARKE MATTHEW , SIDOROV NIKITA
Published: February 2009

Letβ∈(1,2). Eachx∈[0,1/(β−1)] can be represented in the formwhere εk∈{0,1} for allk(aβ-expansion ofx). If$\beta >{(1+\sqrt 5)}/{2}$, then, as is well known, there always existx∈(0,1/(β−1)) which have a uniqueβ-expansion. We study (purely) periodic uniqueβ-expansions and show that for eachn≥2 there exists$\beta _n\in [{(1+\sqrt 5)}/{2},2)$such that there are no unique periodicβ-expansions of smallest periodnforβ≤βnand at least one such expansion forβ>βn. Furthermore, we prove thatβk<βmif and only ifkis less thanmin the sense of the Sharkovskiĭ ordering. We give two proofs of this result, one of which is independent, and the other one links it to the dynamics of a family of trapezoidal maps.
The Mañé–Conze–Guivarc’h lemma for intermittent maps of the circle
Authors: MORRIS IAN D.
Published: February 2009

We study the existence of solutions g to the functional inequality f≤g ∘T−g+β, where f is a prescribed continuous function, T is a weakly expanding transformation of the circle having an indifferent fixed point, and β is the maximum ergodic average of f. Using a method due to T. Bousch, we show that continuous solutions g always exist when the Hölder exponent of f is close to 1. In the converse direction, we construct explicit examples of continuous functions f with low Hölder exponent for which no continuous solution g exists. We give sharp estimates on the best possible Hölder regularity of a solution g given the Hölder regularity of f.
Transitivity of Euclidean-type extensions of hyperbolic systems
Authors: MELBOURNE I. , NIŢICĂ V. , TÖRÖK A.
Published: February 2009

Letf:X→Xbe the restriction to a hyperbolic basic set of a smooth diffeomorphism. We show that in the class ofCr(r>0) cocycles with fiber the special Euclidean group SE(n), those that are transitive form a residual set (countable intersection of open dense sets). This result is new for odd values ofn≥3. More generally, we consider Euclidean-type groupsG⋉ℝnwhereGis a compact connected Lie group acting linearly on ℝn. When Fix G={0}, it is again the case that the transitive cocycles are residual. When Fix G≠{0}, the same result holds upon restriction to the subset of cocycles that avoid an obvious and explicit obstruction to transitivity.
Constructing ergodic exponential maps with dense post-singular orbits
Authors: WANG XIUMEI , ZHANG GAOFEI
Published: February 2009

We construct ergodic exponential maps fλ(z)=λez such that the forward orbit of the origin is dense in $\Bbb C$.
Private Revenge and its Relation to Punishment
Authors: ROSEBURY BRIAN
Published: February 2009

In contrast to the vast literature on retributive theories of punishment, discussions of private revenge are rare in moral philosophy. This article reviews some examples, from both classical and recent writers, finding uncertainty and equivocation over the ethical significance of acts of revenge, and in particular over their possible resemblances, in motive, purpose or justification, to acts of lawful punishment. A key problem for the coherence of our ethical conception of revenge is the consideration that certain acts of revenge may be just (at least in the minimal sense that the victim of revenge has no grounds for complaint against the revenger) and yet be generally agreed to be morally wrong. The challenge of explaining adequately why private revenge is morally wrong poses particular difficulty for purely retributive theories of punishment, since without invoking consequentialist reasons it does not seem possible adequately to motivate an objection to just and proportionate acts of revenge.
Headaches, Lives and Value
Authors: DORSEY DALE
Published: February 2009

ConsiderLives for Headaches: there is some number of headaches such that the relief of those headaches is sufficient to outweigh the good life of an innocent person.Lives for Headachesis unintuitive, but difficult to deny. The argument leading toLives for Headachesis valid, and appears to be constructed out of firmly entrenched premises. In this article, I advocate one way to rejectLives for Headaches; I defend a form of lexical superiority between values. Based on an inquiry into the notion of human well-being, I argue that no amount of headaches is sufficient to outweigh the disvalue of the loss of a good life. Though this view has been thought subject to devastating objections, these objections are not dispositive against the form of value superiority I advance here.
Nuclear DNA replication and seed quality
Authors: Sliwinska Elwira
Published: February 2009

The quality of a seed (germination and vigour) is established during its development and maturation, but can be improved by post-harvest processing and pre-sowing treatments. During commercial seed production, maturity is usually estimated visually, relying on experience of the growers, but seed researchers are working to find molecular markers that can be applied easily to help in establishing optimal harvest time. One marker is cell cycle activity expressed as DNA replication in the seeds, analysed by flow cytometry. This fast and accurate method for the estimation of DNA content in plant nuclei allows detection of nuclei at different replication stages in different seed tissues and thus makes it possible to follow changes in the physiological state of a seed. DNA replication, as a late event during germination, can also be used to mark completion of germination and transition to early seedling growth. This information can be useful in the evaluation of seed quality and for following the advancement of priming. Flow cytometric analysis of ploidy can be also used as a basis for control of purity of some polyploid species seed lots.
THE USE OF WHITE PHOSPHORUS AND THE LAW OF WAR
Authors: MacLeod I.J. , Rogers A.P.V.
Published: February 2009

The controversy surrounding recent uses of white phosphorus (WP) to ‘flush-out’ suspected insurgents or in attacks against military targets in open ground has led to a renewed media interest in the legal status of WP-based munitions. An inherent public dislike for weapons that cause death or injury by fire is very natural, so one is entitled to ask whether humanity should not prevail when it comes to anti-personnel uses of such weapons. In the absence of a specific treaty dealing with the use of WP, this article, written jointly by a retired military lawyer and a scientist interested in the law, examines the use of such weapons in practice as well as the relevant legal and scientific background before attempting to reach conclusions about their legality. This involves a consideration of the reasons for the development of WP-based munitions, of their usual military uses and of some unconventional uses of such weapons. There follows an examination of the basic principles of customary international law as well as the treaty provisions dealing with incendiary weapons. Furthermore, because of the various harmful physiological interactions of WP, it was necessary to look closely at the legal provisions on poison, gas and chemical weapons. That demanded an interpretation of multiple aspects of the Chemical Weapons Convention before the legal status of WP could be fully determined. The convention is constructed in such a way that what at first sight appears to be a chemical weapon may not be as a matter of law unless it is consciously applied in a prohibited manner.
UPDATE ON UNITED STATES MILITARY COMMISSIONS
Authors: Finnin Sarah
Published: February 2009

This article provides a detailed update on the progress of the United States military commissions under the regime established by the Military Commissions Act of 2006 for the trial of detainees captured during the War on Terror for so-called war crimes. In particular, the author examines the plea and sentencing of Australian detainee David Hicks, the pre-trial developments in the case of Canadian detainee Omar Khadr, and the early litigation involving the detainees who have been dubbed the ‘September 11 co-conspirators’. The author also touches on the Supreme Court decision inHamdanv.Rumsfeld, some of the significant features of the Military Commission Act, the recent federal court litigation in the case ofBoumedienev.Bush, and the construction of the new military commission building at Guantanamo Bay Naval Base.
AN APPRAISAL OF US PRACTICE RELATING TO ‘ENEMY COMBATANTS’
Authors: Rona Gabor
Published: February 2009

Following the terrorist attacks of 9/11, the United States sought to establish a framework for detaining, interrogating and possibly prosecuting persons suspected of various degrees of connection to international terrorism. There were several factors militating against reliance on a tried and true law enforcement paradigm of arrest and prosecution in federal courts. Perhaps the most significant one, as described by then Attorney General Ashcroft and other senior officials in the Department of Justice, was the felt need for a fundamental shift in approach when dealing with terrorist suspects, from prosecution to prevention of future attacks.

It was presumed that these two interests were at odds: on the one hand, preparing and trying criminal cases, and on the other hand, obtaining actionable intelligence about terrorist groups and their plans; in other words, that the application of criminal justice procedures would hamper the intelligence gathering effort. After all, ‘you have a right to remain silent and a right to an attorney’ (the so-calledMirandawarnings) was not the message that the administration wanted to convey.
RECALLING THE SUBLIME: THE LOGIC OF CREATION IN HAYDN’S CREATION
Authors: KRAMER LAWRENCE
Published: February 2009

In its opening representation of chaos and subsequent depiction of the creation of light, Joseph Haydn’s oratorio The Creation famously begins with two forays into the musical sublime. But the work thereafter devotes itself to recalling the sublime, in the double sense of rescinding the sublime and of making it a matter of memory rather than of practice. This process is already under way in the depiction of light; its progressive advance may be measured in such ensuing episodes as the depictions of the first sun- and moonrise and Adam and Eve’s climactic hymn of praise, ‘Von deiner Güt’’. The withdrawal of the sublime gradually becomes coextensive with the creation itself and the place of humanity in the order of creation, reflecting (and refashioning) a historically specific understanding not only of the sublime but also, and more weightily, of the conditions of possibility for knowing the world and defining the human. Despite its forceful articulation in The Creation, however, this was an understanding already well on its way to becoming obsolete by the end of the eighteenth century.
Evaluating integrated healthcare for refugees and hosts in an African context
Authors: TUEPKER ANAIS , CHI CHUNHUEI
Published: February 2009

This paper argues on ethical and practical grounds for more widespread use of an integrated approach to refugee healthcare, and proposes a basic model of assessment for integrated systems. A defining element of an integrated approach is an equal ability by refugee and host nationals to access the same healthcare resources from the same providers. This differs fundamentally from parallel care, currently the predominant practice in Africa. The authors put forward a general model for evaluation of integrated healthcare with four criteria: (1) improved health outcomes for both hosts and refugees, (2) increased social integration, (3) increased equitable use of healthcare resources, and (4) no undermining of protection. Historical examples of integrated care in Ethiopia and Uganda are examined in light of these criteria to illustrate how this evaluative model would generate evidence currently lacking in debates on the merit of integrated healthcare.
Access as a policy-relevant concept in low- and middle-income countries
Authors: MCINTYRE DI , THIEDE MICHAEL , BIRCH STEPHEN
Published: February 2009

Although access to health care is frequently identified as a goal for health care policy, the precise meaning of access to health care often remains unclear. We present a conceptual framework that defines access to health care as theempowermentof an individual to use health care and as a multidimensional concept based on the interaction (or degree of fit) between health care systems and individuals, households, and communities. Three dimensions of access are identified: availability, affordability, and acceptability, through which access can be evaluated directly instead of focusing on utilisation of care as a proxy for access. We present the case for the comprehensive evaluation of health care systems as well as the dimensions of access, and the factors underlying each dimension. Such systemic analyses can inform policy-makers about the ‘fit’ between needs for health care and receipt of care, and provide the basis for developing policies that promote improvements in the empowerment to use care.
Role of the equatorial ionization anomaly in the development of the evening prereversal enhancement of the equatorial zonal electric field
Authors: Prakash S. , Pallamraju D. , Sinha H. S. S.
Published: February 2009

During the evening prereversal enhancement of the zonal electric field (EPRE) that begins around 1700 LT when the F region neutral winds turn eastward, as assumed here, and continues till the postsunset zonal electric field reversal time, an overall positive feedback is shown to occur between the eastward electric field in the lower side of the flux tube integrated (LSFTI) F region and the increased flux tube integrated Pedersen conductivity (FTIC) of the tropical F region. The increase in this FTIC can take place because of the increase in electron density through the increase in solar flux and the intensification of the equatorial ionization anomaly (EIA). While the influence of EIA on EPRE is immediate, the growth time for EIA is 2 to 3 h. Therefore, for a strong EPRE to occur, a fairly strong EIA is required at 1700 LT which is then sustained by the electric field associated with EPRE during its growth period. This study suggests that the postsunset eastward electric field is due to the combined currents in the equatorial electrojet and the LSFTI F regions that get diverted from the daytime Sq current system and flow from the presunset region toward the postsunset zonal electric field reversal region. Thereafter these currents turn and flow poleward to meet the current continuity requirement of the F region dynamo followed by a westward turn to rejoin the daytime Sq current system in midlatitudes. Thus the currents responsible for EPRE are an extension of the daytime Sq current system.
Horizontal advection, diffusion, and plankton spectra at the sea surface
Authors: Bracco Annalisa , Clayton Sophie , Pasquero Claudia
Published: February 2009

Plankton patchiness is ubiquitous in the oceans, and various physical and biological processes have been proposed as its generating mechanisms. However, a coherent statement on the problem is missing, because of both a small number of suitable observations and an incomplete understanding of the properties of reactive tracers in turbulent media. It has been suggested that horizontal advection may be the dominant process behind the observed distributions of phytoplankton and zooplankton, acting to mix tracers with longer reaction times (Rt) down to smaller scales. Conversely, the relative distributions of sea surface temperature and phytoplankton has been attributed to small‐scale upwelling, where tracers with longer Rt are able to homogenize more than those with shorter reaction times. Neither of the above mechanisms can explain simultaneously the (relative) spectral slopes of temperature, phytoplankton, and zooplankton. Here, with a simple advection model and a large suite of numerical experiments, we concentrate on some of the physical processes influencing the relative distributions of tracers at the ocean surface, and we investigate (1) the impact of the spatial scale of tracer supply, (2) the role played by coherent eddies on the distribution of tracers with different Rt, and (3) the role of diffusion (so far neglected). We show that diffusion determines the distribution of temperature, regardless of the nature of the forcing. We also find that coherent structures together with differential diffusion of tracers with different Rt impact the tracer distributions. This may help in understanding the highly variable nature of observed plankton spectra.
Quantifying glacial moraine age, denudation, and soil mixing with cosmogenic nuclide depth profiles
Authors: Schaller M. , Ehlers T. A. , Blum J. D. , Kallenberg M. A.
Published: February 2009

Glacial boulders and soils on moraines are often dated to quantify the timing of glaciations and/or rates of chemical weathering in moraine chronosequences. A common assumption is that moraine crest erosion and soil mixing are unimportant. However, several studies suggest moraine denudation may be substantial. We evaluate the magnitude of moraine denudation and soil mixing in the Pinedale (∼21 ka) and Bull Lake (∼140 ka) moraines at Fremont Lake (Wyoming, United States) using cosmogenic nuclide depth profiles and a numerical model of moraine erosion and nuclide production and decay. Depth profiles indicate mixing of the surface layer from 40 to 60 cm depth. Age constraints from depth profile dating of cosmogenic nuclides result in ages of 17–24 ka for the Pinedale moraine and 70–127.5 ka for the Bull Lake moraine. These ages are comparable to ages based on the Lal and Chen approach which uses a sample from the mixed layer and the unmixed layer. However, the Lal and Chen approach is difficult to apply in real environments as the mixing depth needs to be determined independently. We find our best fit model based ages for the Bull Lake moraine are younger than independent age constraints from boulder exposure dating due to incomplete mixing. Exposure age constraints from boulders are more straightforward for moraines than ages based on depth profile dating. Finally, we find that moraine crests do significantly erode and are mixed, suggesting that previous weathering and dust accumulation rate studies on moraines provide minimum estimates for these processes.
Galapagos‐OIB signature in southern Central America: Mantle refertilization by arc–hot spot interaction
Authors: Gazel Esteban , Carr Michael J. , Hoernle Kaj , Feigenson Mark D. , Szymanski David , Hauff Folkmar , van den Bogaard Paul
Published: February 2009

Although most Central American magmas have a typical arc geochemical signature, magmas in southern Central America (central Costa Rica and Panama) have isotopic and trace element compositions with an ocean island basalt (OIB) affinity, similar to the Galapagos‐OIB lavas (e.g., Ba/La < 40, La/Yb > 10, 206Pb/204Pb > 18.8). Our new data for Costa Rica suggest that this signature, unusual for a convergent margin, has a relatively recent origin (Late Miocene ∼6 Ma). We also show that there was a transition from typical arc magmas (analogous to the modern Nicaraguan volcanic front) to OIB‐like magmas similar to the Galapagos hot spot. The geographic distribution of the Galapagos signature in recent lavas from southern Central America is present landward from the subduction of the Galapagos hot spot tracks (the Seamount Province and the Cocos/Coiba Ridge) at the Middle American Trench. The higher Pb isotopic ratios, relatively lower Sr and Nd isotopic ratios, and enriched incompatible‐element signature of central Costa Rican magmas can be explained by arc–hot spot interaction. The isotopic ratios of central Costa Rican lavas require the subducting Seamount Province (Northern Galapagos Domain) component, whereas the isotopic ratios of the adakites and alkaline basalts from southern Costa Rica and Panama are in the geochemical range of the subducting Cocos/Coiba Ridge (Central Galapagos Domain). Geological and geochemical evidence collectively indicate that the relatively recent Galapagos‐OIB signature in southern Central America represents a geochemical signal from subducting Galapagos hot spot tracks, which started to collide with the margin ∼8 Ma ago. The Galapagos hot spot contribution decreases systematically along the volcanic front from central Costa Rica to NW Nicaragua.
Improving retrieval of volcanic sulfur dioxide from backscattered UV satellite observations
Authors: Yang Kai , Krotkov Nickolay A. , Krueger Arlin J. , Carn Simon A. , Bhartia Pawan K. , Levelt Pieternel F.
Published: February 2009

Existing algorithms that use satellite measurements of solar backscattered ultraviolet (BUV) radiances to retrieve sulfur dioxide (SO2) vertical columns underestimate the large SO2 amounts encountered in fresh volcanic eruption clouds. To eliminate this underestimation we have developed a new technique, named the Iterative Spectral Fitting (ISF) algorithm, for accurate retrieval of SO2 vertical columns in the full range of volcanic emissions. The ISF algorithm is applied to Ozone Monitoring Instrument (OMI) BUV measurements of the Sierra Negra eruption (Galàpagos Islands, Ecuador) in October 2005. The results represent major improvements over the operational OMI SO2 products. Based on the ISF data, we report the largest SO2 vertical column amount (>1000 Dobson Units (DU), where 1 DU = 2.69 × 1016 molecules/cm2) ever observed by a space borne instrument, implying that very high concentrations of SO2 can occur in the lower troposphere during effusive eruptions.
Buoyant convection resulting from dissolution and permeability growth in vertical limestone fractures
Authors: Chaudhuri A. , Rajaram H. , Viswanathan H. , Zyvoloski G. , Stauffer P.
Published: February 2009

Upward flow through vertical fractures in limestone formations under a geothermal gradient favors dissolution and permeability growth. We investigate the transition from conductive and forced convective regimes to instability and buoyant convection as a result of permeability growth. The onset time for instability and roll height at onset depend on the initial aperture and driving pressure. A modified Rayleigh number criterion is proposed, which provides a unified interpretation of the instability across a wide range of initial aperture and driving pressure. Interaction between buoyant convection and aperture alteration leads to narrow upward flow paths supporting dissolution and precipitation in surrounding downward flow regions.
Paleomagnetism of the Santa Fé Group, central Brazil: Implications for the late Paleozoic apparent polar wander path for South America
Authors: Brandt Daniele , Ernesto Marcia , Rocha‐Campos Antonio Carlos , dos Santos Paulo Roberto
Published: February 2009

Paleomagnetic and rockmagnetic data are reported for the Floresta Formation (Santa Fé Group) of the Sanfranciscana Basin, central Brazil. This formation represents the Permo‐Carboniferous glacial record of the basin and comprises the Brocotó (diamictites and flow diamictites), Brejo do Arroz (red sandstones and shales with dropstones and invertebrate trails), and Lavado (red sandstones) members, which crop out near the cities of Santa Fé de Minas and Canabrava, Minas Gerais State. Both Brejo do Arroz and Lavado members were sampled in the vicinities of the two localities. Alternating field and thermal demagnetizations of 268 samples from 76 sites revealed reversed components of magnetization in all samples in accordance with the Permo‐Carboniferous Reversed Superchron. The magnetic carriers are magnetite and hematite with both minerals exhibiting the same magnetization component, suggesting a primary origin for the remanence. We use the high‐quality paleomagnetic pole for the Santa Fé Group (330.9°E 65.7°S; N = 60; α95 = 4.1°; k = 21) in a revised late Carboniferous to early Triassic apparent polar wander path for South America. On the basis of this result it is shown that an early Permian Pangea A‐type fit is possible if better determined paleomagnetic poles become available.
A global view of the extratropical tropopause transition layer from Atmospheric Chemistry Experiment Fourier Transform Spectrometer O3, H2O, and CO
Authors: Hegglin M. I. , Boone C. D. , Manney G. L. , Walker K. A.
Published: February 2009

The global behavior of the extratropical tropopause transition layer (ExTL) is investigated using O3, H2O, and CO measurements from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE‐FTS) on Canada's SCISAT‐1 satellite obtained between February 2004 and May 2007. The ExTL depth is derived using H2O‐O3 and CO‐O3 correlations. The ExTL top derived from H2O‐O3 shows an increase from roughly 1–1.5 km above the thermal tropopause in the subtropics to 3–4 km (2.5–3.5 km) in the north (south) polar region, implying somewhat weaker troposphere‐stratosphere‐transport in the Southern Hemisphere. The ExTL bottom extends ∼1 km below the thermal tropopause, indicating a persistent stratospheric influence on the troposphere at all latitudes. The ExTL top derived from the CO‐O3 correlation is lower, at 2 km or ∼345 K (1.5 km or ∼335 K) in the Northern (Southern) Hemisphere. Its annual mean coincides with the relative temperature maximum just above the thermal tropopause. The vertical CO gradient maximizes at the thermal tropopause, indicating a local minimum in mixing within the tropopause region. The seasonal changes in and the scales of the vertical H2O gradients show a similar pattern as the static stability structure of the tropopause inversion layer (TIL), which provides observational support for the hypothesis that H2O plays a radiative role in forcing and maintaining the structure of the TIL.
Experiments in a high‐amplitude Kinoshita meandering channel: 1. Implications of bend orientation on mean and turbulent flow structure
Authors: Abad Jorge D. , Garcia Marcelo H.
Published: February 2009

Meandering rivers exhibit complex planform patterns with both upstream and downstream valley oriented meander bends. In order to describe the effects of bend orientation on long‐term river evolution, it is of great importance to be able to describe bend orientation (curvature) effects on the hydrodynamics of the flow as a first approximation. Mean flow and turbulence characteristics were investigated experimentally in a periodic, asymmetric, meandering channel herein called “the Kinoshita channel”. The channel planform configuration retains high‐order harmonic modes. Upstream and downstream valley oriented meander bends can be studied by reversing the flow. A flat, smooth bed (without sediment) condition has been considered to avoid further complexity. Spatial distributions of mean flow (e.g., velocities) and turbulence parameters (Reynolds stresses, turbulent kinetic energy) were observed at several cross sections along the meander wavelength. Measurements show that at the bend apex, the core of maximum velocity is found near the inner bank for both planform orientations. At the same cross section, observations show that when bends are oriented upstream valley, the secondary flow is not as well developed as in the case where bends are oriented downstream valley. Furthermore, for the upstream condition the energy gradient is smaller than that for the downstream condition, suggesting that the friction (i.e., flow resistance) due to curvature is higher for the downstream‐skewed condition. Implications about having upstream and downstream bends in the meandering river migration framework are also discussed herein.
Multiobjective sensitivity analysis to understand the information content in streamflow observations for distributed watershed modeling
Authors: Wagener Thorsten , van Werkhoven Kathryn , Reed Patrick , Tang Yong
Published: February 2009

In a previous paper, van Werkhoven et al. (2008b) demonstrated that the information content of streamflow observations at a watershed outlet is a dynamic entity and is dependent on the spatiotemporal dynamics of the causal precipitation event. This result has important consequences for distributed hydrological model calibration strategies and for the design of observation networks. However, the conclusions drawn were based only on the analysis of the model parameter sensitivities to the hydrograph peak fit because of the use of the root‐mean‐square error objective function. An unanswered question is how will the previous result change if alternative objective functions are used? Here we extend the earlier analysis by adding low‐flow and water balance objective functions. We study their impact on how much information can be extracted during calibration overall and for specific model components (parameters) using a synthetic rainfall‐runoff event. Results suggest that both vertical (within a model cell) and spatial (across cells) sensitivities vary greatly with the objective function used. Timing‐related objective functions show sensitivity largely focused on the area close to the outlet, while a volume‐based objective function shows sensitivity distributed more evenly across the watershed. These results demonstrate the importance of using multiple evaluation metrics when assessing distributed model predictions. The resultant multiobjective sensitivity maps provide helpful tools for assessing the actual information provided by gauges in observation networks and motivate the need for a new generation of dynamic calibration strategies that would consider how the spatial parameter controls on the model response of interest vary in time.
H/D exchange kinetics in pure and HCl doped polycrystalline ice at temperatures near its melting point: Structure, chemical transport, and phase transitions at grain boundaries
Authors: Lu Haiping , McCartney Stephanie A. , Sadtchenko Vlad
Published: February 2009

We report the results of a fast thermal desorption spectroscopy study of the H/D isotopic exchange kinetics in a few micrometer thick, pure polycrystalline ice film and in ice films doped with HCl. Using the isotopic exchange reaction as a probe of transport processes in ice, we determined the effective H/D interdiffusion coefficients, Deff, in pure and doped polycrystalline ice at temperatures ranging from −18to−1°C. In the case of pure polycrystalline ice, Deff demonstrates an Arrhenius dependence on temperature with an effective activation energy of 69±3kJmol−1 and a pre-exponential of 109±0.5μm2ms−1 up to −2°C. According to our analysis, H/D interdiffusion coefficient at the grain boundaries also shows an Arrhenius dependence on temperature with an activation energy of 69±3kJmol−1 and a pre-exponential of 1011±1μm2ms−1. However, the addition of 0.04% of HCl results in a marked deviation of Deff from Arrhenius law at −8°C, which is attributed to premelting at intersections of grain boundaries. We discuss the structure and transport properties of condensed aqueous phase at grain boundaries in polycrystalline ice at various temperatures.
Manganite-based magnetic tunnel junction with piezoelectric barrier
Authors: Mundle R. , Konda R. B. , Bamiduro O. , Yasar O. , Williams F. , Bahoura M. , Pradhan A. K. , Sahu D. R. , Huang J.-L. , Nikonov D. E.
Published: February 2009

We report on the fabrication and tunneling characteristics of pulsed-laser deposited LaSrMnO (LSMO)∕PbZrTiO(PZT)∕LSMO∕SrTiO3 multilayers, using PZT layer as a tunnel barrier. The trilayer films show magnetic onset at about 360K with ferromagnetic hysteresis at room temperature. The microscopic studies show that the effective barrier thickness is reduced due to the presence of defects in the barrier region. Our results suggest that the asymmetric deformation of the barrier potential profile induced by the ferroelectric polarization of PZT influences the tunneling characteristics and can be used for electrically controlled readout in quantum-computing schemes.
Spin-wave analysis of uniaxial nanopillar devices
Authors: Bertotti Giorgio , Bonin Roberto , Serpico Claudio , d’Aquino Massimiliano , Mayergoyz Isaak
Published: February 2009

The spin-wave instability of self-oscillations in uniaxial nanopillar devices is studied. It is demonstrated that under certain conditions these self-oscillations are stable with respect to spin-wave perturbations. This theoretical result is consistent with experimentally observed stability of large angle self-oscillations driven by spin-polarized current injection.
Electrical transport and ac conductivity properties of hydrogenated annealing V-doped ZnO
Authors: Liu S. H. , Huang J. C. A. , Lin C. R. , Qi X.
Published: February 2009

The hydrogenated annealing effects on structure, magnetism, electrical transport, and ac conductivity for V-doped ZnO powders have been systematically investigated. Room temperature ferromagnetism has been observed for the hydrogenated V:ZnO powders. The saturation magnetization increases with hydrogenated annealing temperature (Tha). By the analysis of electrical transport and ac conductivity, the V:ZnO powders show Efros’s variable range hopping and the density of microstructural defects increases with Tha. The results suggest that the fluctuation of the magnetization is strongly correlated with the defect density in V:ZnO powders.
Correlated polaron transport and metal-insulator transition in La1−xSrxMnO3
Authors: Srivastava N. B. , Singh L. N. , Srivastava C. M.
Published: February 2009

The transport behavior of La1−xSrxMnO3 in the antiferromagnetic insulator, ferromagnetic insulator, and ferromagnetic metallic phases is shown to follow from the correlated polaron mechanism and a single transport equation accounts for the temperature dependence of resistivity for 0⩽x⩽0.40 in the 0–400K range. In the low temperature range zero-point lattice vibration plays a dominant role in the transport in the metallic phase.
Structural, magnetic, and ferroelectric properties of multiferroic BiFeO3-based composite films with exchange bias
Authors: Naganuma Hiroshi , Okubo Tomosato , Sekiguchi Sho , Ando Yasuo , Okamura Soichiro
Published: February 2009

Bi Fe O 3 -based composite films with excess iron content were fabricated, and the dependence of their magnetic and ferroelectric properties on the excess iron content was systematically investigated. Structural and magnetic analyses indicated that the specimens might be composed of large antiferromagnetic BiFeO3 grains and small ferromagnetic component. When the iron content was increased, saturation magnetization (Ms) increased and remanent polarization decreased. Antiferromagnetic coupling (Hex) between the antiferromagnetic BiFeO3 grains and the ferromagnetic grains was observed at 10K. It was revealed that grain growth is the key to increasing Ms and Pr and observing Hex at room temperature in BiFeO3-based composite films.
Amplitude-phase coupling in a spin-torque nano-oscillator
Authors: Kudo Kiwamu , Nagasawa Tazumi , Sato Rie , Mizushima Koichi
Published: February 2009

The spin-torque nano-oscillator in the presence of thermal fluctuation is described by the normal form of the Hopf bifurcation with an additive white noise. By the application of the reduction method, the amplitude-phase coupling factor, which has a significant effect on the power spectrum of the spin-torque nano-oscillator, is calculated from the Landau–Lifshitz–Gilbert–Slonczewski equation with the nonlinear Gilbert damping. The amplitude-phase coupling factor exhibits a large variation depending on an in-plane anisotropy under the practical external fields.
Effect of polarized current on the exchange bias in a current-in-plane spin valve
Authors: Tang Xiao-Li , Zhang Huai-Wu , Su Hua , Jing Yu-Lan , Zhong Zhi-Yong , Bai Fei-Ming , Jian Shen
Published: February 2009

Spin-polarized current-changed exchange bias has been observed in NiFe∕Cu∕NiFe∕FeMn spin valve with a current-in-plane geometry. With increasing current pulse, exchange-bias field Hex first decreases and then increases in the opposite direction. Hex shows little dependence on the applied current pulse above certain value. Furthermore, for the samples with different exchange biases, exchange bias field exhibits a clear dependence on the applied pulse. The results provide clear evidence to support the prediction that a spin-polarized current can exert a torque at antiferromagnetic metals due to interactions between polarized electrons and the antiferromagnetic moments.
Micromagnetic simulations of persistent oscillatory modes excited by spin-polarized current in nanoscale exchange-biased spin valves
Authors: Siracusano G. , Finocchio G. , Krivorotov I. N. , Torres L. , Consolo G. , Azzerboni B.
Published: February 2009

We perform three-dimensional micromagnetic simulations of current-driven magnetization dynamics in nanoscale exchange biased spin valves that take account of (i) back action of spin-transfer torque on the pinned layer, (ii) nonlinear damping, and (iii) random thermal torques. Our simulations demonstrate that all these factors significantly impact the current-driven dynamics and lead to a better agreement between theoretical predictions and experimental results. In particular, we observe that at a nonzero temperature and a subcritical current, the magnetization dynamics exhibits nonstationary behavior in which two independent persistent oscillatory modes are excited which compete for the angular momentum supplied by spin-polarized current. Our results show that this multimode behavior can be induced by combined action of thermal and spin transfer torques.
Spin-transfer interactions in exchange-biased spin valves
Authors: Wei Zhen , Basset Julien , Sharma Amit , Bass Jack , Tsoi Maxim
Published: February 2009

We extend to a new antiferromagnetic alloy, IrMn, point-contact based studies of the effect of a large current density on the exchange bias at antiferromagnet/ferromagnet (AFM/F) interfaces. Similarly to the case of AFM=CoFe, a negative current density ∼1012A∕m2 injected through the F=CoFe into an IrMn∕CoFe interface was found to increase the exchange bias, while a positive current decreased it. The model used to describe the data for FeMn∕CoFe, based on predicted current-induced torques on AFM, can explain the new data.
Photoelectric emission from the alkali metal doped vacuum-ice interface
Authors: Vondrak Tomas , Meech Stephen R. , Plane John M. C.
Published: February 2009

The photoelectron photoemission spectra and thresholds for low coverages of Li and K adsorbed on water-ice have been measured, compared with photoionization spectra of the gas-phase atoms, and modeled by quantum chemical calculations. For both alkali metals the threshold for photoemission is dramatically decreased and the cross section increased on adsorption to the water-ice surface. Quantum chemical calculations suggest that the initial state is formed by the metal atoms adsorbed into the water-ice surface, forming a state with a delocalized electron distribution. This state is metastable and decays on the hundreds of seconds time scale at 92 K. The decay is markedly faster for Li than for K, probably due to diffusion into the ice film.
Combining the nuclear-electronic orbital approach with vibronic coupling theory: Calculation of the tunneling splitting for malonaldehyde
Authors: Hazra Anirban , Skone Jonathan H. , Hammes-Schiffer Sharon
Published: February 2009

The nuclear-electronic orbital (NEO) method is combined with vibronic coupling theory to calculate hydrogen tunneling splittings in polyatomic molecules. In this NEO-vibronic coupling approach, the transferring proton and all electrons are treated quantum mechanically at the NEO level, and the other nuclei are treated quantum mechanically using vibronic coupling theory. The dynamics of the molecule are described by a vibronic Hamiltonian in a diabatic basis of two localized nuclear-electronic states for the electrons and transferring proton. This ab initio approach is computationally practical and efficient for relatively large molecules, and the accuracy can be improved systematically. The NEO-vibronic coupling approach is used to calculate the hydrogen tunneling splitting for malonaldehyde. The calculated tunneling splitting of 24.5 cm−1 is in excellent agreement with the experimental value of 21.6 cm−1. This approach also enables the identification of the dominant modes coupled to the transferring hydrogen motion and provides insight into their roles in the hydrogen tunneling process.
Note on “Dynamics of inertia dominated binary drop collisions” [Phys. Fluids 16, 3438 (2004)]
Authors: Pan Kuo-Long , Roisman Ilia V.
Published: February 2009

The analytical approach shown in the paper [I. V. Roisman, “Dynamics of inertia dominated binary drop collisions,” Phys. Fluids 16, 3438 (2004)] has been found not to yield physically consistent results, for which the theoretically predicted initial kinetic energy of the radially expanding lamella is negative. Such theoretical predictions do not allow the ensuing computation of the flow field. The code for the numerical predictions of the evolution of the drop diameter includes a computational bug with which only a quarter of the dissipated energy is accounted for. Three possible sources of the error are identified: the assumed velocity field in the lamella, the shape of the lamella at the initial phase of drop deformation, and the energy balance formulation of the problem. A possible way for the improvement of the modeling of the dynamics of the initial stage of drop collision is proposed.
Effect of attractive polymer-pore interactions on translocation dynamics
Authors: Chen Ying-Cai , Wang Chao , Zhou Yan-Li , Luo Meng-Bo
Published: February 2009

The effect of attractive polymer-pore interaction on the translocation of polymer chain through a nanopore under electric field is studied by using dynamical Monte Carlo method. The translocation dynamics is remarkably influenced by the interaction. The translocation time for chain moving through nanopore is strongly dependent on the interaction. It reaches minimum at a moderate interaction which is found to be roughly independent of electric field as well as chain length. At weak interaction region, chain spends long time to overcome the barrier of the pore entrance, i.e., the chain is trapped at the entrance. While at strong interaction region, chain is difficult to leave the nanopore, that is, the chain is trapped at the exit of nanopore. The phenomenon is discussed from the view of free energy landscape.
Effects of the orbital self-interaction in both strongly and weakly correlated systems
Authors: Tablero C.
Published: February 2009

The orbital occupation, which is the centerpiece of both self-interaction and several metal-insulator transition analyses, as well as of the local density or generalized gradient approximation with a Hubbard term, is not well defined, in the sense that it is partially ambiguous. A general treatment can be applied to both strongly and weakly correlated systems. When it is applied to an intermediate- and partially filled band within of the host semiconductor gap whose width is less than the semiconductor gap, the original single band can either split as in a Mott transition or not. The former situation is usual and almost always generalized. However the latter also takes place and results from a dilution effect of the self-interaction where a large orbital correlation is reduced if there are other orbital contributions with lower self-interaction in the band. The key is in the choice of the subspace of correlated orbitals. This effect can neither be ignored nor discarded for those systems where there is a substantial mix of states. Examples of these behaviors will be presented and compared to other results. Moreover, the combination of different Hubbard terms acting on different atomic state subspaces can also be used to correct the spurious self-interaction of the bands and the gap underestimation. The relationship between these terms applied to different subspaces of correlated electrons will be presented.
An optimal modified method for a two-dimensional inverse heat conduction problem
Authors: Qian Zhi
Published: February 2009

We consider a two-dimensional inverse heat conduction problem which is severely ill-posed, i.e., the solution (if it exists) does not depend continuously on the data. From the frequency domain, we propose an optimal modified method to solve the problem in the presence of noisy data. We give and prove the optimal convergence estimate, which shows that the regularized solution is dependent continuously on the data and is an approximation of the exact solution of the two-dimensional inverse heat conduction problem.