bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of l-carnitine on metabolism and performance of sows
Authors: Eder Klaus
Published: June 2009

In recent years, l-carnitine has been used increasingly as a supplement in livestock animals. The present review gives an overview of the effects of dietary l-carnitine supplementation on the reproductive performance of sows. Results concerning the effect of l-carnitine supplementation during pregnancy on litter sizes are controversial. There are some studies reporting an increased number of piglets born alive per litter, while others could not find such an effect. In contrast, most studies performed show consistently that l-carnitine supplementation to a sow diet low in native carnitine during gestation increases piglet and litter weights at birth and enhances growth of litters during the suckling period. Biochemical mechanisms underlying the favourable effect of carnitine on intra-uterine growth have not been fully elucidated. There is, however, some evidence that carnitine influences the insulin-like growth factor-axis in sows and leads to greater placentae, which in turn improves intra-uterine nutrition, and stimulates oxidation of glucose in the fetuses. These effects may, at least in part, be responsible for higher birth weights of piglets. The stimulating effect of carnitine on growth of the litters might be due to an improved suckling behaviour of piglets born to l-carnitine-supplemented sows, causing the sows' milk production to rise. In conclusion, recent studies have clearly shown that dietary l-carnitine supplementation increases the reproductive performance of sows. These findings suggest that endogenous de novo synthesis of carnitine is insufficient to meet the metabolic requirement of sows during gestation.
DISCRETE TIME REPRESENTATIONS OF COINTEGRATED CONTINUOUS TIME MODELS WITH MIXED SAMPLE DATA
Authors: Chambers Marcus J.
Published: June 2009

This paper derives an exact discrete time representation corresponding to a triangular cointegrated continuous time system with mixed stock and flow variables and observable stochastic trends. The discrete time model inherits the triangular structure of the underlying continuous time system and does not suffer from the apparent excess differencing that has been found in some related work. It can therefore serve as a basis for the study of the asymptotic sampling properties of estimators of the model's parameters. Some further analytical and computational results that enable Gaussian estimation to be implemented are also provided.
Understanding Variation in the Design of China's New Co-operative Medical System
Authors: Brown Philip H. , de Brauw Alan , Du Yang
Published: June 2009

Although the New Co-operative Medical System (NCMS) was expected to operate in all rural Chinese counties by the end of 2008, county governments were given significant leeway in the design of the local programmes. As a result, fundamental characteristics of NCMS programmes vary dramatically between counties. Such heterogeneity in programme design may influence satisfaction with the NCMS in each county, and thus each programme's prospects for success. This article uses survey data collected by the authors to consider five distinct measures of success. We find that households respond favourably to making emigrants eligible for coverage and to lowering the spending threshold for reimbursement eligibility. However, households are less likely to have received reimbursement in counties that require referrals or limit treatment to approved hospitals. Finally, out-of-pocket expenditures associated with catastrophic health care may still be too high to facilitate treatment of the rural poor.
“Little Quilted Vests to Warm Parents' Hearts”: Redefining the Gendered Practice of Filial Piety in Rural North-eastern China
Authors: Shi Lihong
Published: June 2009

This article explores the transformation of the gendered practice of filial piety in China, which traditionally places sons at the centre and relegates daughters to a peripheral role within their natal families. Based on my ethnographic fieldwork in a rural community in north-eastern China, this article suggests a transformed opinion on filial piety, considering daughters as more filial, as is vividly expressed by the Chinese saying “A daughter is like a little quilted vest to warm her parents' hearts.” Meanwhile, elderly parents have modified traditional standards of filial practice to encompass a desire for an expression of intimate care, respect and practical support from adult children. Further examination suggests three major factors contributing to the transformation of the gendered practice of filial piety: reinterpreted intergenerational relations, women's increased filial practice to their natal parents, and an increased desire of the elderly for an emotional bond with their children.
Environmental Activism, Social Networks and the Internet
Authors: Sullivan Jonathan , Xie Lei
Published: June 2009

Social networks and the internet both have a substantial individual effect on environmental activism in China. In this article, we speculate that social linking patterns between environmental actors, which often facilitate activism on the ground, may also exist in cyberspace in the form of an online network. The article addresses the following empirical questions. Does such an online network exist? If so, who are the constituent actors? Are these the same actors observed on the ground? In addressing these questions the article aims to contribute to the growing debate on the implications of the internet for the potential emergence of social movements in China.
Randomized Greedy Algorithms for Independent Sets and Matchings in Regular Graphs: Exact Results and Finite Girth Corrections
Authors: GAMARNIK DAVID , GOLDBERG DAVID A.
Published: June 2009

We derive new results for the performance of a simple greedy algorithm for finding large independent sets and matchings in constant-degree regular graphs. We show that forr-regular graphs withnnodes and girth at leastg, the algorithm finds an independent set of expected cardinalitywheref(r) is a function which we explicitly compute. A similar result is established for matchings. Our results imply improved bounds for the size of the largest independent set in these graphs, and provide the first results of this type for matchings. As an implication we show that the greedy algorithm returns a nearly perfect matching when both the degreerand girthgare large. Furthermore, we show that the cardinality of independent sets and matchings produced by the greedy algorithm inarbitrarybounded-degree graphs is concentrated around the mean. Finally, we analyse the performance of the greedy algorithm for the case of random i.i.d. weighted independent sets and matchings, and obtain a remarkably simple expression for the limiting expected values produced by the algorithm. In fact, all the other results are obtained as straightforward corollaries from the results for the weighted case.
Deterministic Edge Weights in Increasing Tree Families
Authors: KUBA MARKUS , WAGNER STEPHAN
Published: June 2009

In this work we study edge weights for two specific families of increasing trees, which include binary increasing trees and plane-oriented recursive trees as special instances, where plane-oriented recursive trees serve as a combinatorial model of scale-free random trees given by the m = 1 case of the Barabási–Albert model. An edge e = (k, l), connecting the nodes labelled k and l, respectively, in an increasing tree, is associated with the weight we = |k − l|. We are interested in the distribution of the number of edges with a fixed edge weight j in a random generalized plane-oriented recursive tree or random d-ary increasing tree. We provide exact formulas for expectation and variance and prove a normal limit law for this quantity. A combinatorial approach is also presented and applied to a related parameter, the maximum edge weight.
Implementation of dynamic bias and digital predistortion to enhance efficiency and linearity in a 100 W RF amplifier with OFDM signal
Authors: Bacque Ludovic , Nanfack-Nkondem Gregoire , Bouysse Philippe , Neveux Guillaume , Nebus Jean Michel , Rebernak William , Lapierre Luc , Barataud Denis , Quéré Raymond
Published: June 2009

This paper presents a technique that enables both efficiency and linearity enhancements of power amplifiers (PA) used in communication systems. It consists in the implementation of a dynamic bias control combined with digital base-band predistortion. The aim of this paper is to describe a methodology and successive steps of the design procedure to reach optimum performances in terms of power added efficiency (PAE) and linearity. It is here applied to a 100 W wide-band lateral diffused metal oxide semiconductor (LDMOS) push–pull amplifier (50–500 MHz) driven by orthogonal frequency division multiplexing (OFDM) signals. When the amplifier is driven by a continuous wave (CW) signal and operates at a constant 28 V drain bias voltage, it exhibits 100 W output power and 60% PAE. When it is driven by an OFDM signal, a 10 dB output power back-off is necessary to have a −25 dBc adjacent channel power ratio (ACPR) and PAE decreases down to 10%. By properly implementing an envelope tracking bias system, 40 W output power along with 38% PAE and −27 dBc ACPR have been reached. Applying base-band digital predistortion provides additional linearity improvements at high PAE (for only one point PAE lost, a 5 dB improvement is obtained for ACPR).
Digitally assisted equalization of third-order intermodulation products in wideband direct conversion receivers
Authors: Keehr Edward A. , Hajimiri Ali
Published: June 2009

An effective linearization technique capable of equalizing IM3 products resulting from an arbitrary out-of-band blocking scenario in a wideband direct conversion receiver is presented. IM3 products are regenerated in the RF analog domain of a low-power mixed-signal feedforward path and are used to cancel analogous signal terms in the original receiver at digital baseband via adaptive equalization. The composite SAW-less receiver achieves an improvement in effective IIP3 from −7.1 to +5.3 dBm under worst-case UMTS Region 1 blocking when the feedforward path is active.
Neglektdyslexie – Ätiologie, Diagnostik und Therapie einer vernachlässigten Störung
Authors: Heidler Maria-Dorothea
Published: June 2009

Die Neglektdyslexie ist alltagsrelevante Folge eines Neglekts, in der Forschung und bei der Entwicklung effektiver Behandlungsmethoden jedoch stark unterrepräsentiert.

Typische Fehler sind Omissionen, Substitutionen und Additionen von Wörtern und Buchstaben in der kontraläsionalen Raumhälfte mit resultierender Beeinträchtigung des Lesesinnverständnisses. Häufigste Ursache sind Läsionen des rechten Parietallappens – oft mit Ausdehnung in den Okzipital- und Temporallappenbereich.

Anhand des 3-Stufen-Modells der visuellen Wortrekognition von Caramazza & Hillis (1990) können Neglektdyslexien unterteilt werden in spatiale (stimuluszentrierte) und positionale (wortzentrierte) Formen.

Bislang existieren keine störungsspezifischen Programme zur Therapie der Neglektdyslexie, so dass Übungen zur Behandlung von zentralen, hemianopen und Entwicklungsdyslexien adaptiert werden müssen. Dabei müssen neglektspezifische Phänomene (wie Anosognosie, fehlender Leidensdruck, Konfabulationsneigung oder ein geringer selbständiger Transfer) berücksichtigt werden.
Zur Versorgungssituation im Bereich der ambulanten neuropsychologischen Therapie – eine bundesweite Totalerhebung
Authors: Mühlig Stephan , Rother Aline , Neumann-Thiele Anja , Scheurich Armin
Published: June 2009

Hintergrund: In Deutschland wird die Anzahl von Patienten mit Indikation für eine ambulante neuropsychologische Therapie auf jährlich ca. 40.000 – 60.000 geschätzt. Dem stehen bundesweit lediglich ca. 200 ambulant tätige Psychologische Psychotherapeuten (PPT) mit neuropsychologischer Qualifikation gegenüber. Ziele und Fragestellungen: Welche Patienten mit welchen Merkmalen und Störungsbildern werden von neuropsychologischen PPT mit welchen Charakteristika wie, in welchen Settings, wie lange und mit welchem Erfolg behandelt? Methodik und Design: Totalerhebung aller ambulanten neuropsychologischen Therapeuten in Deutschland (GNP-Register) mittels Fragebogen zu fünf Themenbereichen: 1) Therapeutencharakteristika, 2) Praxismerkmale, 3) Patientencharakteristika, 4) strukturelle Bedingungen, 5) Überweisungsprozesse. Stichprobe: Auswertungsstichprobe N=118 (Ausschöpfungsquote: 65 %). Ergebnisse: Die Versorgungsdichte bezogen auf die Bevölkerungszahl beträgt ca. 1:360.000 (West-Ost-Vergleich 3:1). Neuropsychologische Therapeuten besitzen i.d.R die Approbation als PPT und behandeln zu 70 % neuropsychologisch erkrankte Patienten mit einer Kombination aus neuropsychologischen Interventionsmethoden und sonstigen Richtlinienverfahren. Die häufigsten Ursachen neuropsychologischer Störungsbilder sind Schädel-Hirn-Traumata und cerebrovaskuläre Erkrankungen, die dominierenden Funktionsstörungen liegen im Bereich Aufmerksamkeit, Konzentration und Affektivität. Die überwiegende Mehrheit der Patienten mit einer neuropsychologischen Störung weist eine psychische Komorbidität auf. In der Selbstbeurteilung der Therapeuten werden die Therapieziele zu etwa zwei Dritteln erreicht. Conclusio: Um die Versorgungslage zu verbessern, muss die ambulante neuropsychologische Psychotherapie sozialrechtlich besser geregelt sowie die Ausbildungskapazität deutlich erhöht werden.
Impulsive but Fatal Self-Poisoning with Pesticides Among South Asians in Nickerie, Suriname
Authors: van Spijker B.A.J. , Graafsma T. , Dullaart H.I.A. , Kerkhof A.J.F.M.
Published: June 2009

Background: Intentional self-poisoning with pesticides is a serious problem in many developing countries. It is a commonly used method among South Asians all over the world. Aims: To describe the circumstances and characteristics of suicides in Nickerie, e, in order to gain insight into why South Asians commonly use self-poisoning. Methods: An exploratory psychological autopsy study was conducted among 19 survivors of 13 suicides in the Nickerie district in Suriname. Results: Impulsivity plays an important role in self-poisonings, as well as aggression and easy accessibility of pesticides. Conclusions: Possible answers to the question why South Asians often use self-poisoning as a method for suicide may be found in culture, upbringing, styles of communication and genetics. However, more research is needed to further explore these hypotheses.
Suicidal Behavior in Four Ethnic Groups in The Hague, 2002–2004
Authors: Burger Irene , van Hemert Albert M. , Schudel Willem J. , Middelkoop Barend J.C.
Published: June 2009

Background: Suicidal behavior is a severe public health problem. Aims: To determine the rates of attempted and completed suicide among ethnic groups in The Hague, The Netherlands (2002–2004). Methods: By analyzing data on attempted and completed suicide (from the psychiatric department of general medical hospitals; the psychiatric emergency service and the municipal coroners). Results: Turkish and Surinamese females aged 15–24 years were at highest risk for attempted suicide (age-specific rate 545 / 100,000 and 421 / 100,000 person-years, respectively). Both rates were significantly higher than in the same age group of Dutch females (246 / 100,000 person-years). Turkish (2%) and Surinamese (7%) had lower repeat suicide-attempt rates than did Dutch (16%) females aged 15–24. Significantly lower suicide-attempt rates were found for Surinamese than for Dutch females aged 35–54 years. Differences were not explained by socioeconomic living conditions. The ratio fatal/nonfatal events was 4.5 times higher in males than in females and varied across age, gender, and ethnicity strata. Completed suicide was rare among migrant females. No completed suicides were observed in the Turkish and Surinamese females aged 15–24 years. Conclusions: The study demonstrates a high risk of attempted suicide and a low risk of completed suicide among young Turkish and Surinamese females.
A Case Control Study of Suicides in China with and Without Mental Disorder
Authors: Zhang Jie , Zhou Liang
Published: June 2009

Background: Chinese suicide samples have provided opportunities to study the differences between suicides with and without psychiatric diagnoses. Aims: To examine the differences between suicides with and without mental disorders. Methods: Sixty-six suicides and 66 living controls were studied with psychological autopsy interviews in rural China. Those who died by suicide with (n = 45) and without (n = 21) mental disorders were compared on demographic characteristics, suicidal behavior, social support, life events, and depressive symptoms (as measured by the Hamilton Depression Rating Scale, HAMD). Results: Suicides with and without psychiatric diagnoses had significant differences in many demographic and social factors. In comparison with suicides with psychiatric diagnoses, suicides without psychiatric diagnoses were younger, were better educated, had higher income, were more likely to kill themselves using pesticides or other poisons, were less likely to have a history of prior suicide attempt, had less long-term life events and more recent life events, and scored lower on HAMD. Conclusions: These two groups might be from two different populations. This finding has important implications for more effective and targeted suicide prevention strategies in China.
Deliberate Self-Harm in the Emergency Department
Authors: Shahid Muhammad , Khan Murad M. , Saleem Khan Muhammad , Jamal Yasir , Badshah Aaref , Rehmani Rifat
Published: June 2009

Background: Suicidal behavior is an understudied subject in Pakistan, a South-Asian developing country with a predominantly Muslim population. Aims: This study examined the characteristics and management of patients presenting with Deliberate Self-Harm (DSH) to the Emergency Department (ED) of a tertiary care teaching hospital in Karachi, Pakistan. Methods: A retrospective chart review of all patients (n = 98), over a period of 12 months was carried out. The demographic details of patients; method of DSH and, if drugs were used, their type, route, and quantity; reason for DSH; past psychiatric history; and outcome were recorded. Results: The mean age of subjects was 23.5 years. The majority of patients were female; most had used drugs for DSH. After initial treatment in the ED, 34 patients were admitted to medical wards for further treatment, 12 were discharged from ED, while 52 patients left against medical advice. The main reasons for leaving against medical advice were financial constraints and fear of legal issues. Seven patients had at least one previous episode of DSH. Conclusions: Patients who left the ED without psychosocial assessment are at increased risk for repetition of DSH as well as suicide.
Characteristics of Suicidal Behavior in a Turkish Sample
Authors: Ozdel Osman , Varma Gulfizar , Atesci Figen C. , Oguzhanoglu Nalan K. , Karadag Filiz , Amuk Tarkan
Published: June 2009

Background: Suicidal behavior is one of the most important problems in psychiatric clinics. Several sociodemographic and clinical characteristics may have different effects on suicidal behavior. Aims: To examine the sociodemographic and clinical characteristics of a sample of 144 suicide attempters admitted to a Turkish emergency clinic for a suicide attempt. Methods: All subjects were interviewed by a consultant psychiatrist. For all individuals, data on DSM-IV psychiatric diagnoses, sociodemographic data, Beck’s Hopelessness Scale (BHS), Becks’s Suicidal Ideation Scale (SIS), and Beck’s Suicidal Intention Scale (BSIS) were collected. Results: The majority of suicide attempters were females characterized by low educational status and low religious orientation. Drug overdose was the most common method of suicide attempt and conflict within the family was the most fre uent psychological stress factor. Three- uarters of attempters (74.6%) met DSM-IV criteria for at least one psychiatric diagnosis. Of these, 28.5% met criteria for major depressive disorder. Suicide attempters with depression tended to be immigrant, urban dwellers with high scores on the suicide intent scale. Conclusions: In the present study, the findings are useful in showing the risk factors related to suicidal behavior.
Rethinking Suicide Bombing
Authors: Aggarwal Neil
Published: June 2009

Background: Current issues in the emerging psychiatric literature on suicide bombing tend to center around the pathologies of suicide bombers and the role of psychiatry as an adequate tool for analysis. Aims: Attention to broader social science research may allow mental health professionals to develop more accurate models of behavior to explain and possibly prevent future attacks. Methods: The psychiatric literature on suicide bombing was reviewed and compared to similar anthropological literature. Results: A probe into the methodologies of researching suicide bombing, definitions of “war” and “terrorism”, and beliefs on life, death, homicide, and suicide demonstrate that most of the psychiatric literature reflects a particular perspective which aspires towards a certain universalism. Conclusions: Anthropological approaches can disclose standpoints taken for granted since any interventions with respect to suicide bombing must eventually account for values which are ultimately culturally determined.
Horizontal and vertical interseismic velocity fields in the Vanuatu subduction zone from GPS measurements: Evidence for a central Vanuatu locked zone
Authors: Bergeot N. , Bouin M. N. , Diament M. , Pelletier B. , Régnier M. , Calmant S. , Ballu V.
Published: June 2009

We analyzed interseismic velocity fields along the Vanuatu arc subduction zone from more than 45 GPS station measurements spanning 15 years. Convergence with respect to the Australian plate (AP) is normal to the trench, with amplitudes that vary greatly from a maximum of 170 mm a−1 at Vanikoro to 27 mm a−1 facing the D'Entrecasteaux Ridge (DER). Motions expressed relative to the Pacific plate (PP) highlight arc segmentation. Both the northern and southern segments undergo back‐arc spreading in a roughly NE‐SW direction, rotating anticlockwise and clockwise, respectively, while the central block moves eastward at a faster rate with respect to the PP than to the AP. More convergence is therefore accommodated at the eastern bound of the arc than at the Vanuatu trench. A right lateral strike‐slip movement (26 ± 1 mm a−1) along a zone normal to the trench (direction N70°) is necessary to accommodate the rate variation between the central and southern parts of the arc. Horizontal and vertical rates indicate partitioning between Malekula–southernmost Santo and central‐northern Santo blocks. Simple elastic modeling of the interseismic stage deformation gives locked zone characteristics (25° dip and 50 km width) and a 54 mm a−1 long‐term convergence rate between the AP and the central part of the Vanuatu arc from GPS horizontal and vertical velocities estimated south of the DER. The modeling does not fit the observed velocities facing the DER, probably because it does not account for the inelastic deformation associated with buoyant ridge subduction and back‐arc thrusting.
A spatially explicit model of runoff, evaporation, and lake extent: Application to modern and late Pleistocene lakes in the Great Basin region, western United States
Authors: Matsubara Yo , Howard Alan D.
Published: June 2009

A spatially explicit hydrological model was applied to the Great Basin in the western United States to predict runoff magnitude and lake distributions under modern and late Pleistocene conditions. The model iteratively routes runoff through depression to find a steady state solution and was calibrated with mean annual precipitation, pan evaporation, temperature, and stream runoff data. The predicted lake distribution provides a close match to present‐day lakes. For the late Pleistocene, the sizes of lakes Bonneville and Lahontan are well predicted by linear combinations of 0.2°–5.8°C decreases in temperature and corresponding increases in precipitation from 2.0 to 1.0 times modern values. This corresponds to runoff depths ranging from 1.7 to 4.1 times the present values and yearly evaporation from 0.4 to 1 times modern values. To reproduce Lake Manly, however, combinations of temperature decreases up to 9°C or precipitation up to 2.8 times the present values were required.
Glacial isostatic adjustment and nonstationary signals observed by GRACE
Authors: Tregoning Paul , Ramillien Guillaume , McQueen Herbert , Zwartz Dan
Published: June 2009

Changes in hydrologic surface loads, glacier mass balance, and glacial isostatic adjustment (GIA) have been observed using data from the Gravity Recovery and Climate Experiment (GRACE) mission. In some cases, the estimates have been made by calculating a combination of the linear rate of change of the time series and periodic seasonal variations of GRACE estimates, yet the geophysical phenomena are often not stationary in nature or are dominated by other nonstationary signals. We investigate the variation in linear rate estimates that arise when selecting different time intervals of GRACE solutions and show that more accurate estimates of stationary signals such as GIA can be obtained after the removal of model‐based hydrologic effects. We focus on North America, where numerical hydrological models exist, and East Antarctica, where such models are not readily available. The root mean square of vertical velocities in North America are reduced by ∼20% in a comparison of GRACE‐ and GPS‐derived uplift rates when the GRACE products are corrected for hydrological effects using the GLDAS model. The correlation between the rate estimates of the two techniques increases from 0.58 to 0.73. While acknowledging that the GLDAS model does not model all aspects of the hydrological cycle, it is sufficiently accurate to demonstrate the importance of accounting for hydrological effects before estimating linear trends from GRACE signals. We also show from a comparison of predicted GIA models and observed GPS uplift rates that the positive anomaly seen in Enderby Land, East Antarctica, is not a stationary signal related to GIA.
GRACE‐derived ice‐mass variations over Greenland by accounting for leakage effects
Authors: Baur O. , Kuhn M. , Featherstone W. E.
Published: June 2009

After more than 6 years in full operational mode, the Gravity Recovery and Climate Experiment (GRACE) satellite mission provides the opportunity to derive global secular mass changes from space‐geodetic observations. Crucial for a reliable estimate of secular mass changes is the ability to correct for spectral and spatial leakage effects. In order to account for any leakage signal, we present and apply a four‐step procedure, including a validation step based on forward gravity modeling. Most notably, our method is characterized by the separation and quantification of individual leakage sources. We test and apply our procedure to the Greenland area, which exhibits the strongest secular trend signal. On the basis of simulation studies, we demonstrate that leakage‐out effects are dominant for the Greenland area, and if not accounted for, mass‐change rates will be underestimated. Analyzing time‐variable GRACE gravity fields covering 6 whole years (August 2002 to July 2008, inclusive), we estimate the ice‐volume loss over Greenland to be −177 ± 12 km3 a−1. This value is the average derived from monthly gravity field models provided by CSR, GFZ and JPL, with individual contributions of −242 ± 14 km3 a−1, −194 ± 24 km3 a−1 and −96 ± 23 km3 a−1, respectively. We highlight that without taking leakage effects into account, mass‐change amplitudes over Greenland are reduced by a factor of 2. Despite the rather large spread of the results among GRACE processing centers, our results are in better agreement with the findings from alternative GRACE analysis methods and InSAR observations.
Planktonic growth and grazing in the Columbia River plume region: A biophysical model study
Authors: Banas N. S. , Lessard E. J. , Kudela R. M. , MacCready P. , Peterson T. D. , Hickey B. M. , Frame E.
Published: June 2009

A four‐box model of planktonic nutrient cycling was coupled to a high‐resolution hindcast circulation model of the Oregon‐Washington coast to assess the role of the Columbia River plume in shaping regional‐scale patterns of phytoplankton biomass and productivity. The ecosystem model tracks nitrogen in four phases: dissolved nutrients, phytoplankton biomass, zooplankton biomass, and detritus. Model parameters were chosen using biological observations and shipboard process studies from two cruises in 2004 and 2005 conducted as part of the River Influences on Shelf Ecosystems program. In particular, community growth and grazing rates from 26 microzooplankton dilution experiments were used, in conjunction with analytical equilibrium solutions to the model equations, to diagnose key model rate parameters. The result is a simple model that reproduces both stocks (of nutrients, phytoplankton, and zooplankton) and rates (of phytoplankton growth and microzooplankton grazing) simultaneously. Transient plume circulation processes are found to modulate the Washington‐Oregon upwelling ecosystem in two ways. First, the presence of the plume shifts primary production to deeper water: under weak or variable upwelling winds, 20% less primary production is seen on the inner shelf, and 10–20% more is seen past the 100 m isobath. River effects are smaller when upwelling is strong and sustained. Second, increased retention in the along‐coast direction (i.e., episodic interruption of equatorward transport) causes a net shift toward older communities and increased micrograzer impact on both the Oregon and Washington shelves from the midshelf seaward.
Time reversal imaging of synthetic volcanic tremor sources
Authors: Lokmer Ivan , O'Brien Gareth S. , Stich Daniel , Bean Christopher J.
Published: June 2009

Time reversal of seismic wavefields recorded at active volcanoes may provide images of the source process for long‐period (LP) or volcanic tremor events directly, independent of assumptions about extent, geometry and mechanics of the source. Time reversal methods involve propagating the original time series from many receiver locations back into the medium. The reversed signals then focus at their origin due to constructive interference, elucidating the source location, extent and radiation pattern. In practice, focusing may be blurred due to inaccurate Earth models or sparse sampling of the wavefield at the surface. Here, we investigate the feasibility of this method for several synthetic volcanic tremor sources and present a gallery of time reversal source images. Wave propagation is computed numerically in a 2D volcano model with realistic topography. Our results indicate that time reversal may be applicable in volcanic settings, possibly yielding new insights into volcano‐seismic LP or tremor sources.
Tailward flows with positive BZ in the near‐Earth plasma sheet
Authors: Ohtani S. , Miyashita Y. , Singer H. , Mukai T.
Published: June 2009

The present study examines tailward flows in the central plasma sheet using Geotail measurements at X ≥ −31 RE. A focus is placed on the midnight near‐Earth 8 > X ≥ −15 RE and ∣Y∣ < 5 RE) region. It is found that the BZ component is predominantly positive when the X component of the perpendicular flow velocity is negative and that a substantial portion (37%) of earthward magnetic flux transport is canceled by tailward flows. This ratio is larger than farther down the tail (−15 > X ≥ −31 RE), 25%, suggesting that there is a cause of tailward flows that works favorably in the near‐Earth region. The tailward flow velocity occasionally exceeds 200 km/s. The results of a superposed epoch analysis and case studies of such fast tailward flows are summarized as follows: (1) the typical duration of a fast tailward flow is 1 min; (2) EY is negative, suggesting that the fast tailward flow is an electric drift; (3) the local magnetic configuration tends to become more dipolar; (4) the ion temperature and density increases and decreases, respectively, and there is no significant change in ion pressure; (5) a fast tailward flow is often preceded by a fast earthward flow; and (6) the Y component of the flow velocity is generally smaller than . It is also found that the geosynchronous magnetic field on the night side rarely changes during these fast tailward flows. The rebound of fast earthward flows is suggested as the most plausible cause of fast tailward flows.
Brownian motion in Robertson–Walker spacetimes from electromagnetic vacuum fluctuations
Authors: Béssa Carlos H. G. , Bezerra V. B. , Ford L. H.
Published: June 2009

We consider the effects of the vacuum fluctuations of a quantized electromagnetic field on particles in an expanding universe. We find that these particles typically undergo Brownian motion and acquire a nonzero mean squared velocity that depends on the scale factor of the universe. This Brownian motion can be interpreted as due to noncancellation of anticorrelated vacuum fluctuations in the time-dependent background spacetime. Alternatively, one can interpret this effect as the particles acquiring energy from the background spacetime geometry, a phenomenon that cannot occur in a static spacetime. We treat several types of coupling between the electromagnetic field and the particles and several model universes. We also consider both free particles, which, on the average, move on geodesics, and particles in bound systems. There are significant differences between these two cases, which illustrates that nongeodesic motion alters the effects of the vacuum fluctuations. We discuss the possible applications of this Brownian motion effect to cosmological scenarios.
Raman scattering of phonon-plasmon coupled modes in self-assembled GaN nanowires
Authors: Jeganathan K. , Debnath R. K. , Meijers R. , Stoica T. , Calarco R. , Grützmacher D. , Lüth H.
Published: June 2009

We report the determination of free-electron concentration and mobility of free-standing GaN nanowires (NWs) by line shape analysis of the coupled longitudinal optical phonon-plasmon Raman modes (L+). The E2high phonon mode at 566.9 cm−1 with a sharp linewidth of 2.8 cm−1 indicates strain free NWs with high crystalline perfection. The lattice temperature of the NWs was varied between 313 and 472 K by varying the excitation laser beam power. For unintentionally doped samples at room temperature, an average electron concentration and mobility of strain free NWs were found to be ∼2×1017 cm−3 and 460 cm2/V s, respectively. We have shown that the electron concentration does not change significantly over a temperature range between 313 and 472 K. The electron mobility decreases at high temperatures, in agreement with literature data for compact layers. For Si-doped NWs, the L+ phonon peak is strongly upshifted indicating a higher free-carrier concentration of about 1×1018 cm−3. Asymmetric broadening observed at the lower frequency side of the L+ phonon peak might be ascribed to the enhancement in surface optical modes due to the high surface-to-volume ratio of NWs.
In situ high energy x-ray synchrotron diffraction study of the synthesis and stoichiometry of LaFeAsO and LaFeAsO1−xFy
Authors: McCallum R. W. , Yan J.-Q. , Rustan G. E. , Mun E. D. , Singh Yogesh , Das S. , Nath R. , Bud’ko S. L. , Dennis K. W. , Johnston D. C. , Canfield P. C. , Kramer M. J. , Kreyssig A. , Lograsso T. A. , Goldman A. I.
Published: June 2009

The reaction path for the synthesis of LaFeAsO and LaFeAsO1−xFy by solid state reaction was studied by in situ high temperature x-ray diffraction technique and differential thermal analysis in the temperature interval 100°C⩽T⩽1150°C. Starting with LaAs, Fe2O3, Fe, and LaF3 as precursors, the results show that the synthesis is characterized by three temperature intervals: (1) Below 500°C the sequential reduction of Fe2O3 and Fe3O4 takes place through the oxidization of LaAs. Below 400°C, Fe2O3 is reduced to Fe3O4 by LaAs and then at 400°C<T<500°C Fe3O4 is further reduced to Fe. (2) In the temperature interval 500°C<T<800°C, multiple intermediate reactions take place resulting in the formation of FeAs and La2O3. (3) The formation of LaFeAsO based phase could be unambiguously resolved above 800°C. For both LaFeAsO and LaFeAsO1−xFy, FeAs is a primary impurity at high temperatures that melts at ∼1040°C. Possible reaction pathways and the difference between F-free and F-doped samples are discussed.
Method for analyzing E×B probe spectra from Hall thruster plumes
Authors: Shastry Rohit , Hofer Richard R. , Reid Bryan M. , Gallimore Alec D.
Published: June 2009

Various methods for accurately determining ion species’ current fractions using E×B probes in Hall thruster plumes are investigated. The effects of peak broadening and charge exchange on the calculated values of current fractions are quantified in order to determine the importance of accounting for them in the analysis. It is shown that both peak broadening and charge exchange have a significant effect on the calculated current fractions over a variety of operating conditions, especially at operating pressures exceeding 10−5 torr. However, these effects can be accounted for using a simple approximation for the velocity distribution function and a one-dimensional charge exchange correction model. In order to keep plume attenuation from charge exchange below 30%, it is recommended that pz≤2, where p is the measured facility pressure in units of 10−5 torr and z is the distance from the thruster exit plane to the probe inlet in meters. The spatial variation of the current fractions in the plume of a Hall thruster and the error induced from taking a single-point measurement are also briefly discussed.
Enhanced room temperature magnetoresistance and cluster spin glass behavior in Mo doping La0.67Sr0.33MnO3
Authors: Chen L. , He J. H. , Mei Y. , Cao Y. Z. , Liu B. Q. , Zhu Z. W. , Xu Z. A.
Published: June 2009

The structural, magnetic, and transport properties of Mo doping La0.67Sr0.33Mn1−xMoxO3 (x=0–0.04) manganite system have been investigated by x-ray diffraction, scanning electron microscopy, magnetization, and magnetoresistance measurements. The Mo doping in Mn site is found to lower the Curie temperature Tc slightly and induce the cluster spin glass behavior in ferromagnetic state of La0.67Sr0.33MnO3. The room temperature magnetoresistance of Mo doping La0.67Sr0.33Mn1−xMoxO3 is found to be 50% higher than that of La0.67Sr0.33MnO3 without Mo doping. The significant enhancement for room temperature magnetoresistance could likely be attributed to the presence of the cluster spin glass state caused by the Mo doping.
Material properties dependence of ballistic phonon transmission through two coupled nanocavities
Authors: Huang Wei-Qing , Zou Ming-Liang , Huang Gui-Fang , Yao Jing-Jing , Hu Wangyu
Published: June 2009

We investigate the influence of material properties of two coupled nanocavities on ballistic phonon transport in a semiconductor nanowire at low temperatures. For two identical-size nanocavities their material properties obviously affect the phonon transmission, the frequency of resonant transmission, especially the number n, and positions of the low-frequency gaps. When the two cavities are made of different materials, a new type gap appears in the spectrum. Moreover their positions depend respectively on the material parameters of each cavity. At lower temperatures, the thermal conductance can be enhanced by using different material parameters of cavities from those of the main nanowire. These results suggest new directions that can be explored for forming gaps and resonance phonons, for controlling thermal conductance at different temperature ranges in nanophononics.
Metamaterials for optical security
Authors: Martínez A. , García-Meca C. , Ortuño R. , Rodríguez-Fortuño F. J. , Martí J.
Published: June 2009

In this letter we introduce the concept of optical security marks based on photonic metamaterials. We propose that a metamaterial with strong negative magnetic activity in the visible wavelength regime can be used to create a security mark that can be incorporated in any object to ensure its authenticity. The sophisticated nanofabrication processes needed to manufacture the metamaterial contribute to avoid counterfeiting. To illustrate the concept, a particular configuration consisting of silver nanohoops is analyzed.
Phase structure, dielectric properties, and relaxor behavior of (K0.5Na0.5)NbO3–(Ba0.5Sr0.5)TiO3 lead-free solid solution for high temperature applications
Authors: Du Hongliang , Zhou Wancheng , Luo Fa , Zhu Dongmei , Qu Shaobo , Pei Zhibin
Published: June 2009

The (1−x)(K0.5Na0.5)NbO3–x(Ba0.5Sr0.5)TiO3 (KNN-BST) solid solution has been synthesized by conventional solid-state sintering in order to search for the new lead-free relaxor ferroelectrics for high temperature applications. The phase structure, dielectric properties, and relaxor behavior of the (1−x)KNN-xBST solid solution are systematically investigated. The phase structure of the (1−x)KNN-xBST solid solution gradually changes from pure perovskite phase with an orthorhombic symmetry to the tetragonal symmetry, then to the pseudocubic phase, and to the cubic phase with increasing addition of BST. The 0.90KNN-0.10BST solid solution shows a broad dielectric peak with permittivity maximum near 2500 and low dielectric loss (<4%) in the temperature range of 100–250 °C. The result indicates that this material may have great potential for a variety of high temperature applications. The diffuse phase transition and the temperature of the maximum dielectric permittivity shifting toward higher temperature with increasing frequency, which are two typical characteristics for relaxor ferroelectrics, are observed in the (1−x)KNN-xBST solid solution. The dielectric relaxor behavior obeys a modified Curie–Weiss law and a Vogel–Fulcher relationship. The relaxor nature is attributed to the appearance of polar nanoregions owing to the formation of randon fields including local electric fields and elastic fields. These results confirm that the KNN-based relaxor ferroelectrics can be regarded as an alternative direction for the development of high temperature lead-free relaxor ferroelectrics.
On the space-charge boundary layer inside the nozzle of a cutting torch
Authors: Prevosto L. , Kelly H. , Mancinelli B.
Published: June 2009

A numerical study of the space-charge sheath adjacent to the nozzle wall of a cutting torch is presented. The hydrodynamic model corresponds to a collision-dominated sheath and does not assume cold ions, so drift-diffusion-type equations are used. Also an improved expression for the ion-neutral momentum transfer is employed rather than the usual constant ion-mean-free-path or constant ion collision frequency approximations. Assuming a constant electron temperature in the sheath and neglecting the electron inertial term, the continuity and momentum equations for ions and electrons, together with Poisson’s equation, were solved for the electric potential, ion velocities (both normal and tangential components), and for the ion and electron densities. It was found that both the ion and electron densities present a sudden drop at the sheath-plasma edge. The ion density continues to decrease slowly inside the sheath, while the electron density presents a virtually zero value everywhere inside the sheath, the electron thermal conduction flux to the nozzle wall being negligible. These wall results thus become thermally isolated in spite of the high electron temperature in its adjacency. For a nozzle biasing voltage close to the gas breakdown, it was found that the electric field value is high, reaching a value of about 9×106 V m−1 at the exit of the nozzle wall. This value is higher than the average field value across the sheath and is on the order of the breakdown threshold value. This means that an undesired sheath breakdown could occur at the vicinities of the nozzle exit even if the average electric field across the sheath is not strong enough.
Single crystal silicon carbide detector of emitted ions and soft x rays from power laser-generated plasmas
Authors: Torrisi L. , Foti G. , Giuffrida L. , Puglisi D. , Wolowski J. , Badziak J. , Parys P. , Rosinski M. , Margarone D. , Krasa J. , Velyhan A. , Ullschmied U.
Published: June 2009

A single-crystal silicon carbide (SiC) detector was used for measurements of soft x rays, electrons, and ion emission from laser-generated plasma obtained with the use of the Prague Asterix Laser System (PALS) at intensities of the order of 1016 W/cm2 and pulse duration of 300 ps. Measurements were performed by varying the laser intensity and the nature of the irradiated target. The spectra obtained by using the SiC detector show not only the photopeak due to UV and soft x-ray detection, but also various peaks due to the detection of energetic charged particles. Time-of-flight technique was employed to determine the ion kinetic energy of particles emitted from the plasma and to perform a comparison between SiC and traditional ion collectors. The detector was also employed by inserting absorber films of different thickness in front of the SiC surface in order to determine, as a first approximation, the mean energy of the soft x-ray emission from the plasma.
Substrate thermal conductivity effect on heat dissipation and lifetime improvement of organic light-emitting diodes
Authors: Chung Seungjun , Lee Jae-Hyun , Jeong Jaewook , Kim Jang-Joo , Hong Yongtaek
Published: June 2009

We report substrate thermal conductivity effect on heat dissipation and lifetime improvement of organic light-emitting diodes (OLEDs). Heat dissipation behavior of top-emission OLEDs fabricated on silicon, glass, and planarized stainless steel substrates was measured by using an infrared camera. Peak temperature measured from the backside of each substrate was saturated to be 21.4, 64.5, and 40.5 °C, 180 s after the OLED was operated at luminance of 10 000 cd/m2 and 80% luminance lifetime was about 198, 31, and 96 h, respectively. Efficient heat dissipation through the highly thermally conductive substrates reduced temperature increase, resulting in much improved OLED lifetime.
The interactions between surfactants and vesicles: Dissipative particle dynamics
Authors: Huang Kuei-Chun , Lin Chun-Min , Tsao Heng-Kwong , Sheng Yu-Jane
Published: June 2009

The interactions between surfactants and vesicles formed by double-tail amphiphiles are investigated by the dissipative particle dynamics. As the surfactant concentration is increased, vesicle solubilization can be generally described by the three-stage hypothesis including vesicular region, vesicle-micelle coexistence, and mixed micellar region. We study the partition of surfactants between the bilayer phase and the aqueous phase where a higher value of K indicates that more surfactant molecules are incorporated in the bilayer. It is found that ln(K−1) is proportional to the hydrophile-lipophile balance (HLB), which depicts the degree of hydrophilicity associated with a surfactant. As the overall hydrophilicity of surfactants increases, i.e., higher HLB, K declines and vice versa. When the amounts of surfactants reach a critical point, the solubilization begins and the coexistence of vesicles and mixed micelles is observed. Further increase in the surfactant concentration results in total collapse of the vesicle. Consistent with experimental observations, the three stages are identified through the vesicle size-surfactant concentration relation. Our simulations clearly demonstrate the process of the vesicle solubilization and confirm the validity of the three-stage hypothesis.
Direct measurement of transient electric fields induced by ultrafast pulsed laser irradiation of silicon
Authors: Park H. , Zuo J. M.
Published: June 2009

We use 30 kV electron pulses to probe transient electric fields above silicon surfaces by pump-probe. Electron beam deflection at 0.29 mm away from the sample surface on the order of 10−2 degrees is measured as a function of time delay and used to measure the local electric fields. The measured field strength and direction change with time; at the pump laser fluence of 67.7 mJ/cm2, the maximum field reaches 34 kV/m. We model the transient electric fields based on the propagation of electrons emitted from the Si surface and the percentage of electrons escaping from the surface.