bluuebunny/crossref_metadata_2025 huggingface dataset:
Subpixel-Scale Rainfall Variability and the Effects on Separation of Radar and Gauge Rainfall Errors
Authors: Zhang Yu , Adams Thomas , Bonta James V.
Published: January 2008

This paper presents an extended error variance separation method (EEVS) that allows explicit partitioning of the variance of the errors in gauge- and radar-based representations of areal rainfall. The implementation of EEVS demonstrated in this study combines a kriging scheme for estimating areal rainfall from gauges with a sampling method for determining the correlation between the gauge- and radar-related errors. On the basis of this framework, this study examines scale- and pixel-dependent impacts of subpixel-scale rainfall variability on the perceived partitioning of error variance for four conterminous Hydrologic Rainfall Analysis Project (HRAP) pixels in central Ohio with data from Next-Generation Weather Radar (NEXRAD) stage III product and from 11 collocated rain gauges as input. Application of EEVS for 1998–2001 yields proportional contribution of two error terms for July and October for each HRAP pixel and for two fictitious domains containing the gauges (4 and 8 km in size). The results illustrate the importance of considering subpixel variation of spatial correlation and how it varies with the size of domain size, number of gauges, and the subpixel locations of gauges. Further comparisons of error variance separation (EVS) and EEVS across pixels results suggest that accounting for structured variations in the spatial correlation under 8 km might be necessary for more accurate delineation of domain-dependent partitioning of error variance, and especially so for the summer months.
Clinical referral patterns and cognitive profile in mild
cognitive impairment
Authors: Lonie Jane A. , Herrmann Lucie L. , Donaghey Claire L. , Ebmeier Klaus P.
Published: January 2008

Background

There is current interest in exploring the different subtypes of mild
cognitive impairment (MCI), in terms of both their epidemiology and their
cognitive profile.

Aims

To examine the frequency of MCI subtypes presenting to a memory clinic
and to document detailed neuropsychological profiles of patients with the
amnestic subtype.

Method

Consecutive tertiary referrals (n = 187) were
psychiatrically evaluated; 45 patients met criteria for amnestic mild
cognitive impairment (aMCI). A subgroup of 33 patients with aMCI as well
as 21 healthy controls took part in a thorough neuropsychological
examination.

Results

Of the patients who were examined in greater neuropsychological detail,
ten had pure aMCI (none with visual memory impairment only). Fifteen met
criteria for non-amnestic MCI. Fifteen had normal neuropsychological
profiles. Using more than one test increased sensitivity to detect
episodic memory impairment.

Conclusions

Amnestic MCI is an important diagnosis in secondary and tertiary memory
clinics. There is scope to improve the efficacy and sensitivity of the
clinical assessment of this impairment.
Delivering New Vaccines to Adolescents: The Role of School-Entry Laws
Authors: Horlick Gail , Shaw Frederic E. , Gorji Margaret , Fishbein Daniel B. ,   for the Working Group on Legislation, Vaccination and Adolescent Health
Published: January 2008

In the United States, state-based school-entry vaccination laws have been used effectively to rapidly increase vaccination rates among adolescents, in particular, for hepatitis B vaccine. New vaccines for adolescents raise the question of whether and under what circumstances school-entry laws may be used to increase coverage rates with these vaccines. The new vaccines differ somewhat from their predecessors and raise policy and legal issues. For example, some of the new vaccines prevent diseases for which the primary mode of transmission is sexual contact. Mandating these vaccines before school entry has been met with concern by those who believe that mandates for this type of vaccine not only intrude on parental decision-making rights but might also lead to sexual promiscuity among youth. In this article we explore (1) the possible utility of school-entry requirements to increase the delivery of the new vaccines for adolescents, including the legal basis for US school-entry laws, (2) arguments in favor and concerns about the adoption of laws for adolescent vaccination, and (3) the importance of including diverse stakeholders in the deliberative process and formulating and implementing laws in a way that maximizes their acceptance and effectiveness.
Adubação nitrogenada para o milho cultivado em sistema plantio direto, no Estado de Alagoas
Authors: Cruz Simério C. S. , Pereira Francisco R. da S. , Santos José R. , Albuquerque Abel. W. de , Pereira Rodrigo G.
Published: January 2008

Objetivou-se, neste trabalho, avaliar os efeitos de doses de N sobre os componentes de produção da cultura do milho cultivado em Sistema Plantio Direto. Utilizaram-se quatro doses de nitrogênio (0, 40, 80 e 120 kg ha-1) e cinco cultivares (AG-9010, TRACTOR, DOW-8550, DKB-395 e AL-34). Todos os tratamentos, exceto a testemunha, receberam 20, 115, 60 e 4 kg ha-1 de N, P(2)0(5) e K2O e Zn, respectivamente. O delineamento estatístico foi em blocos casualisados com quatro repetições em esquema de parcelas subdivididas. Os componentes da produção estudados, foram: população final de plantas por hectare, comprimento de espigas, número de fileira de grãos por espigas, número de espigas e massa de 100 grãos. As produtividades dos materiais utilizados no experimento variaram de 1.900 kg ha-1 na testemunha a 5.662 kg ha-1 para a maior dose de N (120 kg ha-1). Observou-se que, do ponto de vista de rentabilidade, as cultivares DOW-8550 e AG-9010 foram as mais promissoras; contudo, conclui-se que a utilização de 120 kg ha-1 de N permitirá ao agricultor retorno econômico da adubação nitrogenada. Os híbridos e a variedade utilizados mostraram alta eficiência na utilização do N aplicado, sendo os híbridos mais responsivos que a variedade.
Social Capital and Health Care Experiences Among Low-Income Individuals
Authors: Perry Megan , Williams Robert L. , Wallerstein Nina , Waitzkin Howard
Published: January 2008

Objectives. We examined relationships between social capital and health service measures among low-income individuals and assessed the psychometric properties of a theory-based measure of social capital.

Methods. We conducted a statewide telephone survey of 1216 low-income New Mexico residents. Respondents reported on barriers to health care access, use of health care services, satisfaction with care, and quality of provider communication and answered questions focusing on social capital.

Results. The social capital measure demonstrated strong psychometric properties. Regression analyses showed that some but not all components of social capital were related to measures of health services; for example, social support was inversely related to barriers to care (odds ratio=0.73; 95% confidence interval=0.59, 0.92).

Conclusions. Social capital is a complex concept, with some elements appearing to be related to individuals’ experiences with health services. More research is needed to refine social capital theory and to clarify the contributions of social capital versus structural factors (e.g., insurance coverage and income) to health care experiences.
Access to and Use of Health Services Among Undocumented Mexican Immigrants in a US Urban Area
Authors: Nandi Arijit , Galea Sandro , Lopez Gerald , Nandi Vijay , Strongarone Stacey , Ompad Danielle C.
Published: January 2008

Objectives. We assessed access to and use of health services among Mexican-born undocumented immigrants living in New York City in 2004.

Methods. We used venue-based sampling to recruit participants from locations where undocumented immigrants were likely to congregate. Participants were 18 years or older, born in Mexico, and current residents of New York City. The main outcome measures were health insurance coverage, access to a regular health care provider, and emergency department care.

Results. In multivariable models, living in a residence with fewer other adults, linguistic acculturation, higher levels of formal income, higher levels of social support, and poor health were associated with health insurance coverage. Female gender, fewer children, arrival before 1997, higher levels of formal income, health insurance coverage, greater social support, and not reporting discrimination were associated with access to a regular health care provider. Higher levels of education, higher levels of formal income, and poor health were associated with emergency department care.

Conclusions. Absent large-scale political solutions to the challenges of undocumented immigrants, policies that address factors shown to limit access to care may improve health among this growing population.
Viva La Vida: Helping Latino Medicare Beneficiaries With Diabetes Live Their Lives to the Fullest
Authors: Olson Rebecca , Sabogal Fabio , Perez Ana
Published: January 2008

Viva la Vida (Live Your Life) is a call to action for older Latinos to take charge of their diabetes and live life to the fullest. Lumetra, California’s federally designated Medicare quality improvement organization, developed the Viva la Vida project to improve diabetes care among Latino Medicare beneficiaries in 4 Southern California counties. After researching barriers to good diabetes care among Latino seniors, Lumetra designed a multifaceted program targeting health care providers and Medicare beneficiaries through bilingual, low-literacy health education materials and tools, community and provider partnerships, and the mass media. The project succeeded in helping to reduce the disparity in glycosylated hemoglobin testing between White and Latino Medicare beneficiaries in the 4 program counties.
Heterozygous Missense Mutations in the Insulin Gene Are Linked to Permanent Diabetes Appearing in the Neonatal Period or in Early Infancy
Authors: Polak Michel , Dechaume Aurélie , Cavé Hélène , Nimri Revital , Crosnier Hélène , Sulmont Véronique , de Kerdanet Marc , Scharfmann Raphael , Lebenthal Yael , Froguel Philippe , Vaxillaire Martine
Published: January 2008

OBJECTIVE—Permanent neonatal diabetes (PND) is defined by chronic hyperglycemia due to severe nonautoimmune insulin deficiency diagnosed in the first months of life. Several genes, including KCNJ11 and ABCC8, which encode the two subunits of the ATP-sensitive K+ channel (KATP channel) can cause PND. Mutations in the insulin (INS) gene have been recently described in families with neonatal diabetes. Our study aimed to investigate the genetic anomalies and clinical heterogeneity in PND patients who are negative for a KATP channel mutation.

RESEARCH DESIGN AND METHODS—We screened the INS gene by direct sequencing in 38 PND patients and in one child with nonautoimmune early-infancy diabetes, where no mutation in GCK, KCNJ11, and ABCC8 was identified. A detailed clinical phenotyping of the patients was carried out to specify the diabetes features in those found with an INS mutation.

RESULTS—We identified three missense mutations in the INS gene in four probands. Two of four mutations were inherited in a dominant manner, and the familial description evidenced a marked variability in age of diagnosis and disease progression. In our cohort, the INS mutations may represent ∼10% of all permanent neonatal diabetes cases, having a later presentation of diabetes and no associated symptoms compared with cases with KATP channel mutations.

CONCLUSIONS—Heterozygous INS gene mutations can cause isolated permanent early-infancy diabetes and should be assessed in neonatal as well as in childhood diabetes appearing like type 1, when autoimmune markers are absent. New pharmacogenomic strategies may be applicable, since residual β-cell function is still present in some patients.
The combined effects of supersaturation and Ba2+ on the batch cooling crystallization of potassium dihydrogen phosphate
Authors: Zheng Guozong , Liang Jingkui , Li Zhengdong , Su Genbo , Zhuang Xinxin
Published: January 2008

The combined effects of supersaturation and Ba2+ on potassium dihydrogen phosphate (KDP) were investigated in batch cooling suspension crystallization. Growth size, morphology, and impurity Ba2+ adsorbed in the KDP crystals were measured with changing Ba2+ concentration and supersaturation. Significant changes in shapes and volume of the grown crystals have been observed. The results further confirmed that the size and shape of crystals were greatly determined by supersaturation. Ba2+ ions significantly modified the growth habit of KDP crystals. The concentration of Ba2+ ions adsorbed in the crystals increases with the increasing Ba2+ ions in the solutions and supersaturation. The foggy phenomena caused by the addition of Ba to the KDP solution were also described. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New Aldehydes by Catalytic Diene Cycloisomerisations
Authors: Grau Fanny , Bayón J. Carles , Aguirre Pedro A. , Parella Teodor , Duñach Elisabet
Published: January 2008

The Rh‐catalysed hydroformylation of isopropylidenecyclohexane derivatives obtained by intramolecular diene cyclisations affords the corresponding aldehydes in good yields and in a completely chemo‐ and regioselective manner. Diastereoselectivities of ca. 90 % were achieved for all substrates when a bulky phosphite was used as the Rh ligand. Thestereochemical outcomes of the hydroformylation reactions were established by detailed NMR studies. The olfactory evaluation of the different aldehydes is also presented.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
[18F]Fluoropropylsulfonyl chloride: a new reagent for radiolabeling primary and secondary amines for PET imaging
Authors: Li Zheng , Lang Lixin , Ma Ying , Kiesewetter Dale O.
Published: January 2008

In vivo molecular imaging with positron emission tomography (PET) requires the preparation of an appropriate positron‐emitting radiotracer. New methods for the introduction of F‐18 into biologically interesting molecules could increase the availability of specific PET radiotracers and increase the application of PET to the study of human diseases. In this work, [18F]fluoropropylsulfonyl chloride was synthesized from 3‐toluenesulfonyloxypropyl thiocyanate in two steps and was successfully incorporated into molecules containing a reactive amino group. Both a primary amine, L‐phenylalanine ethyl ester hydrochloride, and a secondary amine, 1‐(2‐methoxyphenyl)‐piperazine, were successfully radiolabeled by this method. The entire radiochemical synthesis required 90 min. The products were obtained in 25.7±2.3% (n=3) and 22.8±9.1% (n=6) (EOB). This method provides a useful and easy way to make new F‐18 labeled radiopharmaceuticals for PET imaging. Copyright © 2008 John Wiley & Sons, Ltd.
Preparation and biodistribution of 32P‐labelled hydroxocobalamin and comparison with 57Co‐labelled cobinamide and cyanocobalamin
Authors: Gräsbeck Ralph , Sarparanta Mirkka
Published: January 2008

To study whether in biodistribution studies the phosphorus‐containing side‐chain of cobalamin and the central cobalt atom behave differently, 32P‐ and 57Co‐labelled hydroxocobalamins were biosynthesized. A considerably higher specific activity of the 32P‐labelled compound was achieved than before. Both labelled hydroxocobalamins were administered in physiological quantities subcutaneously and orally to rats. The distributions of the two isotopes did not differ significantly. To explain previously observed slight deviations from this pattern, radiolabelled dicyano cobinamide and cyanocobalamin were prepared and studied in an analogous manner. Generally they behaved as hydroxocobalamin, but with greater accumulation in the liver, possibly reflecting the cyanide‐detoxifying function of this organ. Copyright © 2008 John Wiley & Sons, Ltd.
Interdomain cooperativity of calmodulin bound to melittin preferentially increases calcium affinity of sites I and II
Authors: Newman Rhonda A. , Van Scyoc Wendy S. , Sorensen Brenda R. , Jaren Olav R. , Shea Madeline A.
Published: January 2008

Calmodulin (CaM) is the primary transducer of calcium fluxes in eukaryotic cells. Its two domains allosterically regulate myriad target proteins through calcium‐linked association and conformational change. Many of these proteins have a basic amphipathic α‐helix (BAA) motif that binds one or both CaM domains. Previously, we demonstrated domain‐specific binding of melittin, a model BAA peptide, to Paramecium CaM (PCaM): C‐domain mutations altered the interaction with melittin, whereas N‐domain mutations had no discernable effect. Here, we report on the use of fluorescence and NMR spectroscopy to measure the domain‐specific association of melittin with calcium‐saturated ((Ca2+)4‐PCaM) or calcium‐depleted (apo) PCaM, which has enabled us to determine the free energies of calcium binding to the PCaM‐melittin complex, and to estimate interdomain cooperativity. Under apo conditions, melittin associated with each PCaM domain fragment (PCaM1–80 and PCaM76–148), as well as with the C‐domain of full‐length PCaM (PCaM1–148). In the presence of calcium, all of these interactions were again observed, in addition to which an association with the N‐domain of (Ca2+)4‐PCaM1–148 occurred. This new association was made possible by the fact that melittin changed the calcium‐binding preferences for the domains from sequential (C > N) to concomitant, decreasing the median ligand activity of calcium toward the N‐domain 10‐fold more than that observed for the C‐domain. This selectivity may be explained by a free energy of cooperativity of −3 kcal/mol between the N‐ and C‐domains. This study demonstrates multiple domain‐selective differences in the interactions between melittin and PCaM. Our findings support a model that may apply more generally to ion channels that associate with the C‐domain of CaM under low (resting) calcium conditions, but rearrange when calcium binding triggers an association of the N‐ domain with the channel. Proteins 2008. © 2008 Wiley‐Liss, Inc.
An efficient distributed fault‐tolerant protocol for dynamic channel allocation
Authors: Huang Tingxue , Boukerche Azzedine , Abrougui Kaouther , Williams Jeff
Published: January 2008

Recent demand for mobile telephone services has been growing rapidly while the electromagnetic spectrum of frequencies allocated for this purpose remains limited. Any solution to the channel assignment problem is subject to this limitation, as well as the interference constraint between adjacent channels in the spectrum. The early research focused on the fixed channel allocation and centralized schemes. Recently, distributed channel allocation schemes have received much attention because of their high reliability and scalability. In these schemes, a base station (BS) has to consult with its neighboring BSs in order to assign a channel to a call. If it cannot communicate with its neighbors, it fails in allocating a channel. However, it is a common phenomenon that a BS fails in communicating with its neighboring BSs due to some reasons, such as heavy traffic load. In this paper, we propose a distributed fault‐tolerant channel allocation schemes which can work well under the mobile host (MH) failures, BS failures, and communication link failures. This algorithm is based upon the mutual exclusion model where the channels are grouped into three equal sized groups and each group of channels cannot be shared concurrently within the same cluster. We prove its correctness. We also report our algorithm's performance with several channel systems using different types of call arrival pattern through comparing with a popular generic distributed algorithm for channel allocation DDRA. Copyright © 2008 John Wiley & Sons, Ltd.
Specification of communicating processes: temporal logic versus refusals-based refinement
Authors: Lowe Gavin
Published: January 2008

In this paper we consider the relationship between refinement-oriented specification and specifications using a temporal logic. We investigate the extent to which one can check whether a program in a process algebra, such as Communicating Sequential Processes (CSP), satisfies a temporal logic specification using a refinement-based model checker, such as FDR. We consider what atomic formulae are appropriate in a temporal logic for specifying communicating processes, in particular where one wants to talk about the availability of events. We then show that, perhaps surprisingly, the standard stable failures model is not adequate for capturing specifications in such a logic: instead the refusal traces model must be used. We formalise the logic by giving it a semantics in this model. We show that the temporal operators
eventually
and
until
, and negation, cannot, in general, be tested for via simple refinement checks. For the remaining fragment of the logic, we present a translation into simple refinement checks. Finally, we show that refusal traces equivalence is characterised by a slightly augmented version of that fragment.
Relational concurrent refinement part II: Internal operations and outputs
Authors: Boiten Eerke , Derrick John , Schellhorn Gerhard
Published: January 2008

Two styles of description arise naturally in formal specification: state-based and behavioural. In state-based notations, a system is characterised by a collection of variables, and their values determine which actions may occur throughout a system history. Behavioural specifications describe the chronologies of actions—interactions between a system and its environment. The exact nature of such interactions is captured in a variety of semantic models with corresponding notions of refinement; refinement in state based systems is based on the semantics of sequential programs and is modelled relationally. Acknowledging that these viewpoints are complementary, substantial research has gone into combining the paradigms. The purpose of this paper is to do three things. First, we survey recent results linking the relational model of refinement to the process algebraic models. Specifically, we detail how variations in the relational framework lead to relational data refinement being in correspondence with traces–divergences, singleton failures and failures–divergences refinement in a process semantics. Second, we generalise these results by providing a general flexible scheme for incorporating the two main “erroneous” concurrent behaviours: deadlock and divergence, into relational refinement. This is shown to subsume previous characterisations. In doing this we derive relational refinement rules for specifications containing both internal operations and outputs that corresponds to failures–divergences refinement. Third, the theory has been formally specified and verified using the interactive theorem prover KIV.
Treatment Strategies in 135 Consecutive Patients with Enterocutaneous Fistulas
Authors: Visschers Ruben G. J. , Damink Steven W. M. Olde , Winkens Bjorn , Soeters Peter B. , van Gemert Wim G.
Published: January 2008

Background

Enterocutaneous fistulas (ECF) pose a major challenge to every gastrointestinal (GI) surgeon. Based on earlier studies, a standardized treatment guideline was implemented. The focus of the present study was to assess that guideline and determine prognostic factors for outcome of patients with ECF, and to define a more detailed therapeutic approach including the convalescence time before restorative surgery.

Methods

All patients with ECF treated between 1990 and 2005 were included. Management consisted of controlling Sepsis, Optimization of nutritional state, Wound care, assessment of fistula Anatomy, Timing of surgery, and Surgical strategy (the SOWATS guideline). Prognostic factors were assessed by way of multiple logistic regression analysis.

Results

A total of 135 patients were treated at our unit. Overall closure was achieved in 118 patients (87.4%). Restorative operations for fistula closure were performed after a median of 53 days (range: 4–270 days). Restorative operations were successful in 97/107 patients (90.7%). Thirteen patients (9.6%) died. An abdominal wall defect was the most predominant negative prognostic factor for spontaneous closure (odds ratio [OR] = 0.195, confidence interval [CI] 0.052–0.726, p = 0.015). A strong relation was found between preoperative albumin level and surgical closure (p < 0.001) and mortality (p < 0.001).

Conclusions

Application of the SOWATS guideline allowed a favorable outcome after a short convalescence period. Abdominal wall defects and preoperative hypoalbuminemia are important prognostic variables.
Empowering Community Settings: Agents of Individual Development, Community Betterment, and Positive Social Change
Authors: Maton Kenneth I.
Published: January 2008

The pathways and processes through which empowering community settings influence their members, the surrounding community and the larger society are examined. To generate the proposed pathways and processes, a broad range of studies of community settings were reviewed, in the domains of adult well‐being, positive youth development, locality development, and social change. A set of organizational characteristics and associated processes leading to member empowerment across domains were identified, as well as three pathways through which empowering settings in each domain contribute to community betterment and positive social change. The paper concludes with an examination of the ways that community psychology and allied disciplines can help increase the number and range of empowering settings, and enhance the community and societal impact of existing ones.
Seedling growth responses to water and nutrient augmentation in the understorey of a lowland moist forest, Panama
Authors: Yavitt Joseph B. , Wright S. Joseph
Published: January 2008

We irrigated and fertilized (with nutrients) seedlings of Doliocarpus olivaceus (Dilleniaceae, a shade-tolerant liana), Faramea occidentalis (Rubiaceae, a shade-tolerant understorey tree) and Tetragastris panamensis (Burseraceae, a shade-tolerant canopy tree) growing in the understorey of an old-growth tropical moist forest in Panama to assess the impact of seasonal water availability and nutrient-poor soils on seedling growth rates. In control plots, height growth rates were greater in the dry season than in the wet season for Doliocarpus (21%) and for Faramea (89%), whereas Tetragastris had similar seasonal rates. For numbers of leaves, Faramea had 3.5-fold greater relative growth rates in the dry season than in the wet season, while Doliocarpus and Tetragastris lost leaves (semi-deciduous) during the same period. Irrigation and nutrient augmentation increased height growth rates for all three species (45% to 272%). For Doliocarpus, irrigation and nutrient augmentation prevented leaf fall during the dry season. For Faramea in the dry season, irrigation and nutrient augmentation when applied independently reduced the growth of new leaves by 65% to 87%, but relative growth rates for number of leaves were the same as the control rates in the combined irrigation and nutrient augmentation treatment. The growth of new leaves for Tetragastris responded to dry-season irrigation but not nutrient augmentation. Although all measurements occurred beneath the forest canopy, during the dry season, Tetragastris had a negative relationship between canopy openness and relative growth rate for number of leaves, whereas the other two species had a positive relationship. Our results show that soil resources influence growth rates even in the deep shade of the forest understorey, and demonstrate different responses to soil resources among species that might contribute to niche differentiation and species coexistence.
Infant gaze following and pointing predict accelerated vocabulary growth through two years of age: a longitudinal, growth curve modeling study
Authors: BROOKS RECHELE , MELTZOFF ANDREW N.
Published: January 2008

We found that infant gaze following and pointing predicts subsequent language development. At ages 0 ; 10 or 0 ; 11, infants saw an adult turn to look at an object in an experimental setting. Productive vocabulary was assessed longitudinally through two years of age. Growth curve modeling showed that infants who gaze followed and looked longer at the target object had significantly faster vocabulary growth than infants with shorter looks, even with maternal education controlled; adding infant pointing strengthened the model. We highlight the role of social cognition in word learning and emphasize the communicative-referential functions of early gaze following and pointing.
Accelerated decline in the Arctic sea ice cover
Authors: Comiso Josefino C. , Parkinson Claire L. , Gersten Robert , Stock Larry
Published: January 2008

Satellite data reveal unusually low Arctic sea ice coverage during the summer of 2007, caused in part by anomalously high temperatures and southerly winds. The extent and area of the ice cover reached minima on 14 September 2007 at 4.1 × 106 km2 and 3.6 × 106 km2, respectively. These are 24% and 27% lower than the previous record lows, both reached on 21 September 2005, and 37% and 38% less than the climatological averages. Acceleration in the decline is evident as the extent and area trends of the entire ice cover (seasonal and perennial ice) have shifted from about −2.2 and −3.0% per decade in 1979–1996 to about −10.1 and −10.7% per decade in the last 10 years. The latter trends are now comparable to the high negative trends of −10.2 and −11.4% per decade for the perennial ice extent and area, 1979–2007.
B cells flying solo
Authors: Groom Joanna , Mackay Fabienne
Published: January 2008

Systemic autoimmunity such as systemic lupus erythematosus (SLE) is associated with the loss of B‐cell tolerance, B‐cell dysregulation and autoantibody production. While some autoantibodies may contribute to the pathology seen with SLE, numerous studies have shown that dysregulation of T‐cell function is another critical aspect driving disease. The positive results obtained in clinical trials using T‐cell‐ or B‐cell‐specific treatments have suggested that cooperation between T and B cells probably underlies disease progression in many patients. A similar cooperative mechanism seemed to explain SLE developing in mice overexpressing the B‐cell‐activating factor from the tumor necrosis factor family (BAFF). However, surprisingly, T‐cell‐deficient BAFF transgenic (Tg) mice develop SLE similar to T‐cell‐sufficient BAFF Tg mice, and the disease was linked to innate activation of B cells and production of proinflammatory autoantibody isotypes. In conclusion, dysregulated innate activation of B cells alone can drive disease independently of T cells, and as such this aspect represents a new pathogenic mechanism in autoimmunity.
Synchronization of complex dynamical networks via impulsive control
Authors: Zhang Gang , Liu Zengrong , Ma Zhongjun
Published: January 2008

This paper investigates the problem of synchronization in complex dynamical networks. Based on the stability theory for impulsive differential equations, an impulsive control scheme is proposed to achieve impulsive synchronization for complex dynamical networks with unknown coupling. The synchronization strategy considers the influence of all nodes in the dynamical network and the effect intensity of every node to network synchronization relies on its weight in the network. For practical problems, by choosing appropriately the weights of the nodes in the network, network synchronization can be achieved by only a few useful nodes. Simulated examples are provided by using the chaotic Chua system as nodes of the dynamical network, and the effectiveness of the proposed impulsive control are demonstrated.
An adaptive time step scheme for a system of stochastic differential equations with multiple multiplicative noise: Chemical Langevin equation, a proof of concept
Authors: Sotiropoulos Vassilios , Kaznessis Yiannis N.
Published: January 2008

Models involving stochastic differential equations (SDEs) play a prominent role in a wide range of applications where systems are not at the thermodynamic limit, for example, biological population dynamics. Therefore there is a need for numerical schemes that are capable of accurately and efficiently integrating systems of SDEs. In this work we introduce a variable size step algorithm and apply it to systems of stiff SDEs with multiple multiplicative noise. The algorithm is validated using a subclass of SDEs called chemical Langevin equations that appear in the description of dilute chemical kinetics models, with important applications mainly in biology. Three representative examples are used to test and report on the behavior of the proposed scheme. We demonstrate the advantages and disadvantages over fixed time step integration schemes of the proposed method, showing that the adaptive time step method is considerably more stable than fixed step methods with no excessive additional computational overhead.
Optimal instruments and models for noisy chaos
Authors: Strelioff Christopher C. , Crutchfield James P.
Published: January 2008

Analysis of finite, noisy time series data leads to modern statistical inference methods. Here we adapt Bayesian inference for applied symbolic dynamics. We show that reconciling Kolmogorov’s maximum-entropy partition with the methods of Bayesian model selection requires the use of two separate optimizations. First, instrument design produces a maximum-entropy symbolic representation of time series data. Second, Bayesian model comparison with a uniform prior selects a minimum-entropy model, with respect to the considered Markov chain orders, of the symbolic data. We illustrate these steps using a binary partition of time series data from the logistic and Hénon maps as well as the Rössler and Lorenz attractors with dynamical noise. In each case we demonstrate the inference of effectively generating partitions and kth-order Markov chain models.
On convex surfaces with minimal moment of inertia
Authors: Freitas P. , Laugesen R. S. , Liddell G. F.
Published: January 2008

We investigate the problem of minimizing the moment of inertia among convex surfaces in R3 having a specified surface area. First, we prove that a minimizing surface exists, and derive a necessary condition holding at points of positive curvature. Then we show that an equilateral triangular prism is the optimal triangular prism, that the cube is the optimal rectangular prism, and that the sphere is (locally) optimal among ellipsoids. Many examples of convex surfaces are examined, among which the lowest moment of inertia is achieved by a truncated tetrahedron. The problem of finding the global minimizing surface remains open. The analogous problem in two dimensions has been solved by Sachs and later by Hall, who showed that the equilateral triangle minimizes the moment of inertia, among all convex curves with given length.
Electrically tunable viscosity of dilute suspensions of carbon nanotubes
Authors: Lin Chen , Shan Jerry W.
Published: January 2008

The apparent viscosity of a dilute (volume fraction ϕ=1.5×10−5), single-wall-carbon-nanotube(SWNT)/α-terpineol suspension was experimentally found to more than double at moderate shear rates under an external electric field of strength 160V∕mm. The electrorheological response is interpreted in terms of an electrostatic-polarization model, where the governing parameter is a modified Mason number giving the ratio of viscous to dipole-dipole forces. Analysis of the hydrodynamic and electrostatic forces suggests that the magnitude of the electrorheological response in the dilute SWNT suspension, which is much higher than conventional electrorheological fluids at comparable volume fractions, is due to the high aspect ratio of the nanotubes. Comparison is made to a suspension of glassy carbon spheres, in which a three-order-of-magnitude-higher volume fraction is required to achieve similar increases in the apparent viscosity under the same conditions.
New Bell inequalities for the singlet state: Going beyond the Grothendieck bound
Authors: Pitowsky Itamar
Published: January 2008

Contemporary versions of Bell’s argument [Physics (Long Island City, N.Y.) 1, 195 (1964)] against local hidden variable (LHV) theories are based on the Clauser-Horne-Shimony-Holt (CHSH) [Phys. Rev. Lett. 23, 880 (1969)] inequality and various attempts to generalize it. The amount of violation of these inequalities cannot exceed the bound set by the Grothendieck constants. However, if we go back to the original derivation by Bell and use the perfect anticorrelation embodied in the singlet spin state, we can go beyond these bounds. In this paper, we derive two-particle Bell inequalities for traceless two-outcome observables, whose violation in the singlet spin state go beyond the Grothendieck constants both for the two and three dimensional cases. Moreover, creating a higher dimensional analog of perfect correlations and applying a recent result of Alon et al. [Invent. Math. 163, 499 (2006)], we prove that there are two-particle Bell inequalities for traceless two-outcome observables whose violation increases to infinity as the dimension and number of measurements grow. Technically, these result are possible because perfect correlations (or anticorrelations) allow us to transport the indices of the inequality from the edges of a bipartite graph to those of the complete graph. Finally, it is shown how to apply these results to mixed Werner states, provided that the noise does not exceed 20%.
Effects of N and F passivation on the reliability and interface structure of 700 °C grown ultrathin silicon oxide/Si(100) gate films
Authors: Yamada Hiroshi
Published: January 2008

Correlations between reliability and interfacial structure changes of ultrathin silicon oxide gate films grown at 700 °C with in situ pyrolytic-gas passivation (PGP) were investigated. PGP uses a little pyrolytic N2O and NF3 during ultradry oxidation with pure O2 at less than 1 ppb humidity and has a potential for application to future low-temperature device fabrication processes due to the reliability retention of the films. It was found that the reliability for the 700 °C grown PGP films is much like that of the 800–900 °C grown ones, with an interface state density of less than 1–3×1010/eV cm2 maintained. Quantitative analyses of N, F, and O indicated that this is probably due to microscopic, interfacial structure changes, that is, N and F passivation effectively contributes to compensate inconsistent-state bonding sites and to generate a high-density structure with few dangling bonds.
Figures of merit for focusing mega-electron-volt ion beams in biomedical imaging and proton beam writing
Authors: Ren Minqin , Whitlow Harry J. , Sagari A. R. Ananda , van Kan Jeroen A. , Osipowicz Thomas , Watt Frank
Published: January 2008

A figure of merit (FOM) has been developed for focusing quadrupole multiplet lenses for ion micro- and nanobeam systems. The method which is based on measurement of the central peak of the two-dimensional autocorrelation function of an image provides separate FOM for the horizontal and vertical directions. The approach has been tested by comparison with the edge widths obtained by nonlinear fitting the edge widths of a Ni grid and found to be reliable. The FOM has the important advantage for ion beam imaging of biomedical samples that the fluence needed is considerably lower than for edge fitting.
Tunable Coulomb blockade in nanostructured graphene
Authors: Stampfer C. , Güttinger J. , Molitor F. , Graf D. , Ihn T. , Ensslin K.
Published: January 2008

We report on Coulomb blockade and Coulomb diamond measurements on an etched, tunable single-layer graphene quantum dot. The device consisting of a graphene island connected via two narrow graphene constrictions is fully tunable by three lateral graphene gates. Coulomb blockade resonances are observed and from Coulomb diamond measurements, a charging energy of ≈3.5meV is extracted. For increasing temperatures, we detect a peak broadening and a transmission increase of the nanostructured graphene barriers.
Reducing the contact resistance of bottom-contact pentacene thin-film transistors by employing a MoOx carrier injection layer
Authors: Kumaki Daisuke , Umeda Tokiyoshi , Tokito Shizuo
Published: January 2008

We report on the reduced contact resistance in bottom-contact (BC) pentacene thin-film transistors (TFTs) with a molybdenum oxide (MoOx) carrier injection layer. MoOx layers were placed between the gate insulator and the source-drain (S-D) electrodes instead of the conventional adhesive layer such as Cr or Ti. The performance of the BC pentacene-TFT with the MoOx injection layer was significantly improved at low operating voltages. The contact resistance of the MoOx∕Au S-D electrodes, estimated using the gated-transmission line method, was nearly two orders of magnitude smaller than that of conventional Cr∕Au electrodes at the gate voltage of −10V. The highest performance was obtained with a MoOx injection layer a few nanometers thick, which was comparable to the effective channel thickness of the pentacene-TFT on the gate insulator. This result indicated the importance of the direct connection between the MoOx injection layer and the effective channel to reduce the contact resistance.
Observation of large low field magnetoresistance and large magnetocaloric effects in polycrystalline Pr0.65(Ca0.7Sr0.3)0.35MnO3
Authors: Biswas Anis , Samanta Tapas , Banerjee S. , Das I.
Published: January 2008

Magnetotransport and magnetocaloric properties of polycrystalline Pr0.65(Ca0.7Sr0.3)MnO3 have been studied. Large low field magnetoresistance (∼100% at 75K for 1T field) with high magnetic field sensitivity (∼5000%T−1) has been observed due to the melting of charge ordered state. The system also shows large magnetocaloric effect at ∼215 and 90K. The magnetic entropy change is ∼8 and 5.5J∕kgK, respectively, around these temperatures for a field change from 0to7T. Such huge low field magnetoresistance along with large magnetocaloric effect exhibited by the material is interesting from the application point of view.
Ultrafast dynamics of photoexcited coherent phonon in Bi2Te3 thin films
Authors: Wu Alexander Q. , Xu Xianfan , Venkatasubramanian Rama
Published: January 2008

Nonequilibrium A1g longitudinal optical phonon with a frequency of 1.84THz in bismuth telluride (Bi2Te3) is coherently excited by ultrafast pulses. Time-resolved reflectivity measurements show a distinct second harmonic vibration around 3.68THz at room temperature caused by the nonlinearity of coherent phonon potentially related to the favorable crystal structure of Bi2Te3. The scattering rate between A1g coherent phonon and room temperature incoherent phonon is derived from the pump-fluence-dependent scattering rate of A1g coherent phonon. It is also observed that energy coupling from photoexcited carriers to lattice through coherent phonon vibration is more efficient and faster at higher pump fluence.
Polarization dependent coupling of surface plasmon on a one-dimensional Ag grating with an InGaN∕GaN dual-quantum-well structure
Authors: Shen Kun-Ching , Chen Cheng-Yen , Huang Chi-Feng , Wang Jhy-Yang , Lu Yen-Cheng , Kiang Yean-Woei , Yang C. C. , Yang Ying-Jay
Published: January 2008

The authors report the observation of a polarization-dependent surface plasmon (SP) feature on a one-dimensional Ag-grating structure through the SP coupling with an InGaN∕GaN dual-quantum-well structure closely below the metal grating. Polarized photon output is observed because only the momentum matching condition of the SP mode propagating in the direction perpendicular to the grating grooves can be reached through the diffraction of the fabricated grating and, thus, the SP radiation efficiency is significantly enhanced only in this polarization. The dispersion curve of the observed SP mode shows a group velocity of 2.4×108m∕s, which manifests the SP characteristics in the air/Ag∕GaN grating structure.
Influence of chirp on the femtosecond excitation of a semiconductor microcavity laser
Authors: Kühn Eckhard , Thränhardt Angela , Koch Stephan W. , Stolz Wolfgang , Chatterjee Sangam , Lange Christoph , Rühle Wolfgang W. , Wohlleben Wendel , Motzkus Marcus
Published: January 2008

The time-resolved response of an optically excited vertical-cavity surface-emitting laser is measured for quadratically chirped pump pulses. The experimental results are compared with simulations based on microscopic calculations and qualitatively good agreement is obtained. The theoretical analysis shows that the observed dependence of both, the amplitude and the temporal evolution of the laser response, on the sign and amplitude of the quadratical chirp can be attributed to the excitation-induced dephasing process of the 1s plasma-resonance of the quantum-well barriers.
Evidence for declines in human population densities during the early Upper Paleolithic in western Europe
Authors: Morin Eugène
Published: January 2008

In western Europe, the Middle to Upper Paleolithic (M/UP) transition, dated between ≈35,000 and ≈40,000 radiocarbon years, corresponded to a period of major human biological and cultural changes. However, information on human population densities is scarce for that period. New faunal data from the high-resolution record of Saint-Césaire, France, indicate an episode of significant climatic deterioration during the early Upper Paleolithic (EUP), which also was associated with a reduction in mammalian species diversity. High correlations between ethnographic data and mammalian species diversity suggest that this shift decreased human population densities. Reliance on reindeer (Rangifer tarandus), a highly fluctuating resource, would also have promoted declines in human population densities. These data suggest that the EUP represented for humans a period of significant niche contraction in western Europe. In this context, the possibility that a modern human expansion occurred in this region seems low. Instead, it is suggested that population bottlenecks, genetic drift, and gene flow prevailed over human population replacement as mechanisms of evolution in humans during the EUP.
Ypi1, a Positive Regulator of Nuclear Protein Phosphatase Type 1 Activity inSaccharomyces cerevisiae
Authors: Bharucha Jennifer P. , Larson Jennifer R. , Gao Lu , Daves Lisa K. , Tatchell Kelly
Published: January 2008

The catalytic subunit of protein phosphatase type 1 (PP1) has an essential role in mitosis, acting in opposition to the Ipl1/Aurora B protein kinase to ensure proper kinetochore-microtubule interactions. However, the regulatory subunit(s) that completes the PP1 holoenzyme that functions in this capacity is not known. We show here that the budding yeast Ypi1 protein is a nuclear protein that functions with PP1 (Glc7) in this mitotic role. Depletion of cellular Ypi1 induces mitotic arrest due to activation of the spindle checkpoint. Ypi1 depletion is accompanied by a reduction of nuclear PP1 and by loss of nuclear Sds22, a Glc7 binding partner that is found in a ternary complex with Ypi1 and Glc7. Expression of a Ypi1 variant that binds weakly to PP1 also activates the spindle checkpoint and suppresses the temperature sensitivity of an ipl1-2 mutant. These results, together with genetic interactions among YPI1, GLC7, and SDS22 mutants, indicate that Ypi1 and Sds22 are positive regulators of the nuclear Glc7 activity that is required for mitosis.