bluuebunny/crossref_metadata_2025 huggingface dataset:
Frequency dependence of hysteresis associated with the electromechanical performance of PVDF film
Authors: Hughes O. Richard
Published: October 2007

The thickness strains, the electric displacements, and the hysteresis exhibited by poly(vinylidene fluoride) films under sinusoidal applied electric fields were measured over a range of frequencies from 0.05 to 100 Hz. The loops of strain‐ and electric displacement versus electric field exhibit a shape and hysteresis that undergoes a continuous and reversible change with frequency. At lower frequencies (<5 Hz), the shape and large hysteresis are characteristic of a ferroelectric with degrees of remanent polarization. At higher frequencies (>5 Hz), the shape and slight hysteresis of the loops are representative of a nonremanently polarized ferroelectric. This dependence of shape and hysteresis on frequency is attributed to the difference in rates between the rapid rate by which the polarization of domains of aligned dipoles is reversed in a periodic field and the slower rate by which the polarization is made remanent. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3207–3214, 2007
Have men been overlooked? A comparison of young men and women's experiences of chemotherapy‐induced alopecia
Authors: Hilton Shona , Hunt Kate , Emslie Carol , Salinas Maria , Ziebland Sue
Published: October 2007

Objective: The objective of this study is to compare men and women's accounts of chemotherapy‐induced alopecia.

Design: Secondary analysis of narrative interview data.

Participants: Thirty‐seven people aged 18–38 years, including 11 men and 8 women who had experienced hair loss, interviewed between 2000 and 2005.

Setting: Participants were recruited throughout the United Kingdom.

Results: Hair loss made many men and women acutely aware of their vulnerability and visibility as a ‘cancer patient’. Both men and women described a sense of strangeness or shock when they lost their hair and experienced various negative reactions when people assumed their hairless appearance was a lifestyle choice. The most striking contrast in men's and women's accounts was that women spoke solely of the loss of hair from the head and face above the eye line, and men spoke about losing hair from wider body surfaces. Only women mentioned being encouraged by others to disguise or to prevent hair loss. The results are discussed in relation to gendered assumptions about the distribution of body hair.

Conclusions: Contrary to prevailing assumptions, both women and men described negative (and often similar) feelings about hair loss. Understanding these experiences can help professionals better equip their patients to deal with this aspect of their treatment. Copyright © 2007 John Wiley & Sons, Ltd.
Being the next of kin of a person with a low‐grade glioma
Authors: Edvardsson Tanja , Ahlström Gerd
Published: October 2007

There is a paucity of knowledge for health‐care professionals who come into contact with next of kin of persons diagnosed with low‐grade gliomas. Therefore, the aim of this study was to explore the experience of being the next of kin of an adult person diagnosed with a low‐grade glioma.

Twenty‐eight next of kin of persons with a low‐grade glioma were interviewed. The data were subjected to qualitative content analysis. A quantitative data analysis was added to explore how the themes from the qualitative analysis occurred among different next of kin.

Four main themes emerged: Extremely stressful emotions, Being invisible and neglected, Changed relations and roles, and Enabling strength in everyday life. The first of these occurred mainly in the early period of illness. This theme was especially predominant in the case of the patient's parents. The theme of Changed relations and roles occurred more often among next of kin some years after the person's diagnosis. The most statements occurred in all four themes were by female next of kin.

Many next of kin requested emotional support for themselves and indicated that it is important that health‐care staff should not forget them. Copyright © 2007 John Wiley & Sons, Ltd.
Predictors of employment and lost hours from work in cancer caregivers
Authors: Sherwood Paula R. , Donovan Heidi S. , Given Charles W. , Lu Xiaoli , Given Barbara A. , Hricik Allison , Bradley Sarah
Published: October 2007

This cross‐sectional, descriptive study identified variables associated with caregivers who (1) were employed and (2) reported lost hours from work due to care demands. Family caregivers (N=80) of persons with a primary malignant brain tumor participated in a 45–60 min telephone interview, answering questions regarding the impact of providing care on their emotional health and employment status. Younger caregivers were more likely to be employed. Caregivers were more likely to report lost hours from work when care recipients required assistance with Instrumental Activities of Daily Living (IADLs) and were closer to the time of diagnosis. Data suggest that interventions to assist caregivers in maintaining employment should target caregivers of persons with limitations in physical function and should include strategies to coordinate care to assist with IADLs. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of protein dynamics from residual dipolar couplings using the three dimensional Gaussian axial fluctuation model
Authors: Bouvignies Guillaume , Markwick Phineus R. L. , Blackledge Martin
Published: October 2007

Residual dipolar couplings are potentially very powerful probes of slower protein motions, providing access to dynamic events occurring on functionally important timescales up to the millisecond. One recent approach uses the three dimensional Gaussian Axial Fluctuation model (3D GAF) to determine the major directional modes and associated amplitudes of motions along the peptide chain. In this study we have used standard and accelerated molecular dynamics simulations to determine the accuracy of 3D GAF‐based approaches in characterizing the nature and extent of local molecular motions. We compare modes determined directly from the trajectories with motional parameterization derived from RDCs simulated from the same trajectories. Three approaches are tested, that either suppose a known three‐dimensional structure, simultaneously determine backbone structure and dynamics, or determine dynamic modes in the absence of a structural model. The results demonstrate the robustness of the 3D GAF analysis even in the presence of large‐scale motions, and illustrate the remarkably quantitative nature of the extracted amplitudes. These observations suggest that the approach can be generally used for the study of functionally interesting biomolecular motions. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Residue conservation in viral capsid assembly
Authors: Bahadur Ranjit P. , Janin Joël
Published: October 2007

To evaluate the evolutionary constraints placed on viral proteins by the structure and assembly of the capsid, we calculate Shannon entropies in the aligned sequences of 45 polypeptide chains in 32 icosahedral viruses, and relate these entropies to the residue location in the three‐dimensional structure of the capsids. Three categories of residues have entropies lower than the chain average implying that they are better conserved than average: residues that are buried within a subunit (the protein core), residues that contain atoms buried at an interface between subunits (the interface core), and residues that contribute to several such interfaces. The interface core is also conserved in homomeric proteins and in transient protein–protein complexes, which have only one interface whereas capsids have many. In capsids, the subunit interfaces implicate most of the polypeptide chain: on average, 66% of the capsid residues are at an interface, 34% at more than one, and 47% at the interface core. Nevertheless, we observe that the degree of residue conservation can vary widely between interfaces within a capsid and between regions within an interface. The interfaces and regions of interfaces that show a low sequence variability are likely to play major roles in the self‐assembly of the capsid, with implications on its mechanism that we discuss taking adeno‐associated virus as an example. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Structure of the Drosophila nucleosome core particle highlights evolutionary constraints on the H2A‐H2B histone dimer
Authors: Clapier Cedric R. , Chakravarthy Srinivas , Petosa Carlo , Fernández‐Tornero Carlos , Luger Karolin , Müller Christoph W.
Published: October 2007

We determined the 2.45 Å crystal structure of the nucleosome core particle from Drosophila melanogaster and compared it to that of Xenopus laevis bound to the identical 147 base‐pair DNA fragment derived from human α‐satellite DNA. Differences between the two structures primarily reflect 16 amino acid substitutions between species, 15 of which are in histones H2A and H2B. Four of these involve histone tail residues, resulting in subtly altered protein–DNA interactions that exemplify the structural plasticity of these tails. Of the 12 substitutions occurring within the histone core regions, five involve small, solvent‐exposed residues not involved in intraparticle interactions. The remaining seven involve buried hydrophobic residues, and appear to have coevolved so as to preserve the volume of side chains within the H2A hydrophobic core and H2A‐H2B dimer interface. Thus, apart from variations in the histone tails, amino acid substitutions that differentiate Drosophila from Xenopus histones occur in mutually compensatory combinations. This highlights the tight evolutionary constraints exerted on histones since the vertebrate and invertebrate lineages diverged. Proteins 2008. © 2007 Wiley‐Liss, Inc.
N‐linked glycans of the human insulin receptor and their distribution over the crystal structure
Authors: Sparrow Lindsay G. , Lawrence Michael C. , Gorman Jeffrey J. , Strike Phillip M. , Robinson Christine P. , McKern Neil M. , Ward Colin W.
Published: October 2007

The human insulin receptor (IR) homodimer is heavily glycosylated and contains a total of 19 predicted N‐linked glycosylation sites in each monomer. The recent crystal structure of the IR ectodomain shows electron density consistent with N‐linked glycosylation at the majority of sites present in the construct. Here, we describe a refined structure of the IR ectodomain that incorporates all of the N‐linked glycans and reveals the extent to which the attached glycans mask the surface of the IR dimer from interaction with antibodies or other potential therapeutic binding proteins. The usefulness of Fab complexation in the crystallization of heavily glycosylated proteins is also discussed. The compositions of the glycans on IR expressed in CHO‐K1 cells and the glycosylation deficient Lec8 cell line were determined by protease digestion, glycopeptide purification, amino acid sequence analysis, and mass spectrometry. Collectively the data reveal: multiple species of complex glycan at residues 25, 255, 295, 418, 606, 624, 742, 755, and 893 (IR‐B numbering); multiple species of high‐mannose glycan at residues 111 and 514; a single species of complex glycan at residue 671; and a single species of high‐mannose glycan at residue 215. Residue 16 exhibited a mixture of complex, hybrid, and high‐mannose glycan species. Of the remaining five predicted N‐linked sites, those at residues 397 and 906 were confirmed by amino acid sequencing to be glycosylated, while that at residue 78 and the atypical (NKC) site at residue 282 were not glycosylated. The peptide containing the final site at residue 337 was not recovered but is seen to be glycosylated in the electron density maps of the IR ectodomain. The model of the fully glycosylated IR reveals that the sites carrying high‐mannose glycans lie at positions of relatively low steric accessibility. Proteins 2008. © 2007 Wiley‐Liss, Inc.
Examples of Charging Effects on the Spectral Quality of X‐ray Microanalysis on a Glass Sample Using the Variable Pressure Scanning Electron Microscope
Authors: Le Berre J. F. , Demers H. , Demopoulos G. P. , Gauvin R.
Published: October 2007

The performance of X‐ray microanalysis in the variable pressure or environmental scanning electron microscope (VP‐SEM or ESEM®) is limited by skirting. Under certain conditions, charging effects can occur and change the X‐ray emission, which affects the X‐ray microanalysis. The conventional way to evaluate charging is to calculate the Duane‐Hunt limit by fitting the X‐ray intensity region located below the energy cut‐off. Nevertheless, this method appears to have serious limitations for instance in the case of strong insulators. A perfect example of this limitation is to study the evolution of composition of an alkali glass with time. This paper reports on the evolution of the sodium X‐ray intensity with time depending on accelerating voltage, pressure and presence of a surface coating. For certain conditions, a decrease of sodium X‐ray intensity with time was observed but for other conditions the reverse behavior was noticed. The increase of sodium X‐ray intensity with time was obtained when the force created by the surface electrons was stronger than the force generated by electrons trapped in the interaction volume, whereas the decrease of sodium X‐ray intensity occurred when the force generated by electrons trapped in the interaction volume was the stronger. The variations of sodium X‐ray intensity were also compared to the variation of the Duane‐‐Hunt limit, the determination of which is studied in detail in this article. SCANNING 29: 270–271, 2007. © 2007 Wiley Periodicals, Inc.
Sample size calculations in the presence of competing risks
Authors: Latouche A. , Porcher R.
Published: October 2007

Recently, with the growth of statistical developments for competing risks analysis, some methods have been proposed to compute sample size in this context. These methods differ from a modelling approach: one is based on the Cox regression model for the cause‐specific hazard, while another relies on the Fine and Gray regression model for the subdistribution hazard of a competing risk. In this work, we compare these approaches, derive a new sample size for comparing cumulative incidence functions when the hazards are not proportional (either cause‐specific or subdistribution) and give practical advices to choose the approach best suited for the study question. Copyright © 2007 John Wiley & Sons, Ltd.
Automated discovery of state transitions and their functions in source code
Authors: Walkinshaw Neil , Bogdanov Kirill , Ali Shaukat , Holcombe Mike
Published: October 2007

Finite‐state machine specifications form the basis for a number of rigorous state‐based testing techniques and can help to understand program behaviour. Unfortunately they are rarely maintained during software development, which means that these benefits can rarely be fully exploited. This paper describes a technique that, given a set of states that are of interest to a developer, uses symbolic execution to reverse‐engineer state transitions from source code. A particularly novel aspect of our approach is that, besides determining whether or not a state transition can take place, it also identifies the paths through the source code that govern a transition. The technique has been implemented as a prototype, enabling its preliminary evaluation with respect to real software systems. Copyright © 2007 John Wiley & Sons, Ltd.
Continuous nicotine administration produces selective, age‐dependent structural alteration of pyramidal neurons from prelimbic cortex
Authors: Bergstrom Hadley C. , McDonald Craig G. , French Helen T. , Smith Robert F.
Published: October 2007

Emerging evidence indicates that adolescence represents a developmental window of enhanced nicotine‐induced neuroplasticity in rat forebrain. However, whether nicotine produces age‐dependent structural alteration of neurons from medial prefrontal cortex remains to be determined. We characterized the dendritic morphology of layer V pyramidal neurons from prelimbic cortex following adolescent (P29‐43) or adult (P80‐94) nicotine pretreatment. Nicotine administration was via osmotic pump [initial dose 2.0 mg/(kg day), free base]. Five weeks after drug administration concluded, brains were processed for Golgi‐Cox staining and pyramidal neurons digitally reconstructed for morphometric analysis. Overall, nicotine pretreatment produced increased basilar, but not apical, dendritic length of pyramidal cells, a finding consistent with previous work using adult animals. Given the compelling evidence for morphologically distinct functional subtypes of cortical pyramidal neurons, we endeavored to determine whether nicotine‐induced dendritic alteration was specific to putative structural subtypes. Neurons were segregated into two groups based on the extent of dendritic arbor at the distal portion of the apical tree (i.e., the apical tuft). The size of the apical tuft was quantitatively determined using principal component analysis. Cells with small and elaborate apical tufts were classified as simple and complex, respectively. We found that adult nicotine pretreatment produced increased basilar dendritic length and branch number in simple but not complex pyramidal cells. In contrast, adolescent nicotine pretreatment produced a modest but significant increase in basilar dendritic length in complex but not simple cells. These data suggest that nicotine alters dendritic morphology of specific subpopulations of pyramidal neurons and that the subpopulation affected is dependent on the age of drug exposure. Synapse 62:31–39, 2008. © 2007 Wiley‐Liss, Inc.
Minimally Invasive Ablative Therapies for Invasive Breast Carcinomas: An Overview of Current Literature
Authors: van Esser Stijn , van den Bosch Maurice A. A. J. , van Diest Paul J. , Mali Willem Th. M. , Borel Rinkes Inne H. M. , van Hillegersberg Richard
Published: October 2007

Background

Minimally invasive treatment may be an alternative to breast‐conserving surgery.

Methods

A structured PubMed, Embase, Cochrane, and Web of Science search was performed. Endpoints studied were feasibility, completeness of ablation, timing of the sentinel node biopsy (SNB), imaging modalities, and treatment‐related complications.

Results

A total of 24 articles were retrieved, and the level of evidence varied (2B‐4). Mainly phase II studies with a treat‐and‐resect protocol were analyzed. Up to 100% completeness of ablation was reported for radiofrequency ablation (RFA), cryosurgery, and focused ultrasound (FUS). The oncologic results need further evaluation. Dynamic contrast enhanced MRI seems to be the best method for monitoring treatment response (77% sensitivity, 100% specificity). Ultrasound is suitable for guiding probes into the tumor. There is no consensus on the timing of the SNB.

Conclusions

All studies on minimally invasive ablative modalities published so far show that these techniques are feasible and safe. At this stage only T1 tumors should be ablated in a clinical trial setting; it is unclear which of the modalities is most suitable.
Epilepsy and inborn errors of metabolism in adults: A diagnostic approach
Authors: Sedel F. , Gourfinkel‐An I. , Lyon‐Caen O. , Baulac M. , Saudubray J.‐M. , Navarro V.
Published: October 2007

Inborn errors of metabolism (IEMs) represent poorly known causes of epilepsy in adulthood. Although rare, these are important to recognize for several reasons: some IEMs respond to specific treatments, some antiepileptic drugs interfering with metabolic pathways may worsen the clinical condition, and specific genetic counselling can be provided. We review IEMs potentially revealed by epilepsy that can be encountered in an adult neurology department. We distinguished progressive myoclonic epilepsies (observed in some lysosomal storage diseases, respiratory chain disorders and Lafora disease), from other forms of epilepsies (observed in disorders of intermediary metabolism, including porphyrias, creatine metabolism defects, glucose transporter (GLUT‐1) deficiency, Wilson disease or succinic semialdehyde dehydrogenase deficiency). We propose a diagnostic approach and point out clinical, radiological and electrophysiological features that suggest an IEM in an epileptic patient.
Hereditary spastic paraparesis in adults associated with inborn errors of metabolism: A diagnostic approach
Authors: Sedel F. , Fontaine B. , Saudubray J. M. , Lyon‐Caen O.
Published: October 2007

Spastic paraparesis is a general term describing progressive stiffness and weakness in the lower limbs caused by pyramidal tract lesions. This clinical situation is frequently encountered in adult neurology. The diagnostic survey is usually limited to searching for acquired causes (spinal cord compression, inflammatory, metabolic, infectious diseases) and the so‐called ‘hereditary spastic paraparesis’ Although poorly recognized by neurologists, spastic paraparesis is also one of the multiple presentations of inborn errors of metabolism (IEMs) in children and adults. Pyramidal signs are usually included in a diffuse neurological or systemic clinical picture; however, in some cases spastic paraparesis remains the only symptom for years. Since these metabolic causes are often treatable, it is essential to include them in the general diagnostic approach to spastic paraparesis. Here we review IEMs causing paraparesis in adults.
Shifts in aquatic macroinvertebrate biodiversity associated with the presence and size of an alien crayfish
Authors: Correia Alexandra M. , Anastácio Pedro M.
Published: October 2007

To investigate the effects of Procambarus clarkii on macroinvertebrate diversity, we conducted a mesocosm experiment simulating small pools in rice field pads after the rice season. We hypothesized that crayfish predation would negatively impact macroinvertebrate diversity, and the magnitude of this impact should vary with the size of P. clarkii. We conducted a short‐term mesocosm experiment to determine macroinvertebrate diversity in the presence of three size classes and in the absence of crayfish, as well as the diet composition of crayfish from the three size classes. At the end of the experiments, the diet of crayfish was composed of the most available taxa (Culicidae, Chironomus, Tanytarsini and Orthocladinae). These results also show evidence that, in confined areas, crayfish are important predators of major rice pests such as rice Chironominae larvae. Macroinvertebrate diversity was negatively affected by crayfish presence, but the effect was inversely proportional to crayfish size. The highest diversity index was obtained in the absence of P. clarkii, and juvenile crayfish significantly reduced macroinvertebrate diversity. Thus, the impact of P. clarkii on aquatic macroinvertebrates is size dependent and may be relevant in small pools formed in rice field pads from early autumn to late winter. Overall, our findings suggest that the negative effects of P. clarkii on macroinvertebrate diversity may be particularly strong in local natural assemblages confined to puddles of water or small ponds in wetland areas.
Effects of flooding and artificial burning disturbances on plant species composition in a downstream riverside floodplain
Authors: Ishida Shinya , Nakashizuka Tohru , Gonda Yutaka , Kamitani Tomohiko
Published: October 2007

Our objective was to detect environmental and disturbance factors that determine plant species composition in a downstream riverside floodplain of the Shinano River, where both natural flooding and artificial fire disturbances predominate. We classified the natural vegetation into five types by physiognomy, i.e., burnt field, intact (unburnt) field, early‐successional forest, later‐successional forest, and margin of channel. We deployed 14 transect belts containing 713 plots of 1 m × 1 m at these sites. In the plots, we determined plant occurrences and values of five environmental (soil moisture, soil texture, relative elevation above the river, horizontal distance from the river, and light conditions) and two disturbance factors (scouring of plants by flooding and fire). Plant species compositions and environmental and disturbance factors were different among the sites. Logistic regression analysis showed that burning stimulated the occurrences of herbaceous annuals and conversely constrained those of woody and fern species, suggesting that fire disturbance resets the succession. Scouring of plants by flooding also affected the occurrences of many species, and had a positive influence on that of herbaceous winter annuals in particular. Canonical correspondence analysis indicated that the distributional characteristics of the plant species in the riverside floodplain were influenced primarily by distance from the river, reflecting the magnitude of flood disturbance. We conclude that (1) magnitude of flood disturbance is the primary factor determining plant species composition, and (2) burning maintains early successional vegetation and simultaneously creates a unique plant species composition by stimulating the germination of buried viable seeds transported by flood.
Reliability of pediobarographs for paediatric foot deformity
Authors: Riad Jacques , Coleman Scott , Henley John , Miller Freeman
Published: October 2007

Purpose

Dynamic pediobarograph measures foot–floor contact pressure during walking and provides a quantitative functional assessment. The goal of this study was to assess the reliability of pediobarograph measurements in normal children and in those with cerebral palsy (CP).

Materials and methods

During the first investigation, five non-disabled children and four with CP had three pediobarograph measurements taken of each foot, repeated five times. The pediobarographs were analysed by dividing the foot into five segments; the heel, the lateral midfoot, the medial midfoot, the lateral forefoot and the medial forefoot. A measure of valgus/varus foot posture was defined as the relative medial–lateral difference of combined mid- and forefoot impulse, named valgus/varus index. During the second investigation, 50 children (100 feet) with spastic diplegic CP were studied to calculate the standard error of measurements (SEM), to investigate the number of pediobarograph measurements necessary to obtain accurate results. The third investigation was an inter- and intraobserver study performed on one normal subject's repeated measurements.

Results

In the first investigation, the group with CP had a significantly increased variability in the medial midfoot ( P = 0.013). The variability of the valgus/varus index had a standard deviation of 13%, demonstrating that this measure is relatively stable. The SEM and 95% confidence interval from the second experiment showed that, even if the accuracy increased with the number of measurements, the greatest gain seemed to be contributed by increasing the number of measurements from 3 to 6. The inter- and intraobserver study showed good to mostly excellent agreement.

Conclusion

Pediobarograph measurements can be used to monitor and quantitatively assess the progressive changes of foot deformity over time. Pediobarograph is a reliable measurement that shows little variability between measurements at the same occasion and between measurements on different days. Three to six measurements seems practical and adequate to obtain. The technical aspect of measuring shows good repeatability and agreement between observers.
English shop signs in Macedonia
Authors: Dimova Slobodanka
Published: October 2007

THIS STUDY investigates the extent to which English is used in shop signs and windows as part of the names of businesses and other premises, and of notes, advertisements, and slogans in the city of Veles, in Macedonia: a country in south-eastern Europe established in 1991, after the disintegration of Communist Yugoslavia. It is situated in the southern part of the Balkan Peninsula, and borders on Serbia, Albania, Greece, and Bulgaria. Macedonian, a Slavonic language, is its official tongue: the native language of around 66.5% of the population, while Albanian is native to approximately 22.9%. Other languages used in Macedonia are Turkish, Serbian, Romani, and Rumanian.
Just because it's new doesn't mean people will notice it
Authors: Hilpert Martin
Published: October 2007

LANGUAGE changes all the time. Speakers produce innovations that are novel at first, but become conventionalized as they are used more and more. Some get a fair amount of press. The rise of ‘singular they’ (Has everyone got their handout?) has provoked a heated debate about proper usage (cf. Balhorn 2004). However, not all innovations have such a polarizing effect, as some enter the language below the radar of prescriptivism. As a case in point, the construction just because…doesn't mean… (as in the title of this article) is a fairly recent expression that has developed its own syntactic and semantic properties, but is not perceived as particularly deviant. This article discusses the idiosyncratic properties of this construction, draws a brief sketch of its history, and offers some thoughts on why it could establish itself without attracting much notice.
What price?
Authors: Bulley Michael
Published: October 2007

Some thoughts on the new OED's view of British pronunciation.
PALS: Efficient Or-Parallel execution of Prolog on Beowulf clusters
Authors: PONTELLI ENRICO , VILLAVERDE KAREN , GUO HAI-FENG , GUPTA GOPAL
Published: October 2007

This paper describes the development of thePALSsystem, an implementation of Prolog capable of efficiently exploiting or-parallelism ondistributed-memoryplatforms—specifically Beowulf clusters. PALS makes use of a novel technique, calledincremental stack-splitting. The technique proposed builds on the stack-splitting approach, previously described by the authors and experimentally validated on shared-memory systems, which in turn is an evolution of the stack-copying method used in a variety of parallel logic and constraint systems—e.g., MUSE, YAP, and Penny. The PALS system is the first distributed or-parallel implementation of Prolog based on the stack-splitting method ever realized. The results presented confirm the superiority of this method as a simple yet effective technique to transition from shared-memory to distributed-memory systems. PALS extends stack-splitting by combining it with incremental copying; the paper provides a description of the implementation of PALS, including details of how distributed scheduling is handled. We also investigate methodologies to effectively support order-sensitive predicates (e.g., side-effects) in the context of the stack-splitting scheme. Experimental results obtained from running PALS on both Shared Memory and Beowulf systems are presented and analyzed.
Mars Global Surveyor radio science electron density profiles: Some anomalous features in the Martian ionosphere
Authors: Mahajan K. K. , Singh Sachchidanand , Kumar Ashok , Raghuvanshi Saroj , Haider S. A.
Published: October 2007

We have analyzed some 807 Mars Global Surveyor electron density profiles that are confined to the northern high latitudes and thus are relatively free of the effects of crustal magnetic fields. These profiles have shown some anomalous features in the Martian ionosphere, and one of these is the noticeable variability in number density (Nm) and height (hm) of the primary ionospheric peak on the same day when solar conditions and solar zenith angle have remained the same, a feature not expected from a photochemically controlled layer. We study this feature by generating longitudinal plots of Nm and hm for the 807 profiles and by applying a least squares spectral fit consisting of wave number 1, 2, and 3 components to these data sets. We find some significant relationship between the two parameters, with the troughs in Nm coinciding with the ridges in hm (and vice versa) on the longitudinal scale. An examination at fixed solar zenith angles shows a significant anticorrelation between the two parameters recorded over a period of about 3 months. However, theoretical considerations would support a positive correlation expected in response to changes in the EUV flux that occurred during this period. Further, we observe a large variability in electron density at 160 and 180 km, altitudes in the topside ionosphere, where photochemistry is expected to dominate. This is an additional anomalous feature. No such variability is observed in the topside ionosphere of Venus. We discuss plausible mechanisms like neutral atmosphere dynamics and solar wind interaction to explain some of the features.
Rapid sea level rise and ice sheet response to 8,200‐year climate event
Authors: Cronin T. M. , Vogt P. R. , Willard D. A. , Thunell R. , Halka J. , Berke M. , Pohlman J.
Published: October 2007

The largest abrupt climatic reversal of the Holocene interglacial, the cooling event 8.6–8.2 thousand years ago (ka), was probably caused by catastrophic release of glacial Lake Agassiz‐Ojibway, which slowed Atlantic meridional overturning circulation (AMOC) and cooled global climate. Geophysical surveys and sediment cores from Chesapeake Bay reveal the pattern of sea level rise during this event. Sea level rose ∼14 m between 9.5 to 7.5 ka, a pattern consistent with coral records and the ICE‐5G glacio‐isostatic adjustment model. There were two distinct periods at ∼8.9–8.8 and ∼8.2–7.6 ka when Chesapeake marshes were drown as sea level rose rapidly at least ∼12 mm yr−1. The latter event occurred after the 8.6–8.2 ka cooling event, coincided with extreme warming and vigorous AMOC centered on 7.9 ka, and may have been due to Antarctic Ice Sheet decay.
El Niño–Southern Oscillation and Pacific Decadal Oscillation impacts on precipitation in the southern and central United States: Evaluation of spatial distribution and predictions
Authors: Kurtzman Daniel , Scanlon Bridget R.
Published: October 2007

Understanding and predicting regional impacts of El Niño–Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) on winter (October–March) precipitation can provide valuable inputs to agricultural and water resources managers. Effects of ENSO and PDO on winter precipitation were assessed in 165 climate divisions throughout the southern United States. A continuous region of significantly (P < 0.05) increased (decreased) winter precipitation in response to El Niño (La Niña) conditions in the preceding summer (June–September Southern Oscillation Index (SOI)) extends across the entire southern United States and as far north as South Dakota. Within this region stronger correlations (r ≤ −0.45) are found along the Gulf of Mexico, southern Arizona, and central Nebraska. Winter precipitation differs significantly (P < 0.1) between warm and cold phase PDO periods only in the south central region, with greatest significance centered in Oklahoma. Enhanced negative La Niña anomalies during PDO cold phases are dominant in the central region (Texas to South Dakota) whereas enhanced positive El Niño anomalies during PDO warm phases are dominant in the southwest (Arizona, Nevada, and California) and southeast (Louisiana to Florida). Validation tests of winter precipitation predictions based on summer SOI and/or PDO‐phase show a decrease of 9% to 16% in the relative Mean Absolute Error (MAE) from the MAE obtained by using the mean as a predictor in areas with strong correlation (r < −0.45) between SOI and precipitation. Logistic regression probability models of having above or below average winter precipitation had up to 77% successful predictions. The advantage of having probabilities of exceeding certain precipitation thresholds at the beginning of a hydrologic year makes logistic regression models attractive for decision makers.
Readout of micromechanical cantilever sensor arrays by Fabry-Perot interferometry
Authors: Wehrmeister Jana , Fuß Achim , Saurenbach Frank , Berger Rüdiger , Helm Mark
Published: October 2007

The increasing use of micromechanical cantilevers in sensing applications causes a need for reliable readout techniques of micromechanical cantilever sensor (MCS) bending. Current optical beam deflection techniques suffer from drawbacks such as artifacts due to changes in the refraction index upon exchange of media. Here, an adaptation of the Fabry-Perot interferometer is presented that allows simultaneous determination of MCS bending and changes in the refraction index of media. Calibration of the instrument with liquids of known refraction index provides an avenue to direct measurement of bending with nanometer precision. Versatile construction of flow cells in combination with alignment features for substrate chips allows simultaneous measurement of two MCS situated either on the same, or on two different support chips. The performance of the instrument is demonstrate in several sensing applications, including adsorption experiments of alkanethioles on MCS gold surfaces, and measurement of humidity changes in air.
Neutral penetration in centrifugally confined plasmas
Authors: Ng Sheung-wah , Hassam A. B.
Published: October 2007

Plasma-neutral interactions along the magnetic field are considered for a centrifugally confined plasma wherein a cross-field plasma rotation inhibits plasma escape along the magnetic field. Analytic and numerical solutions from a simple one-dimensional isothermal model are obtained. It is shown that for perfect recycling, the neutral density at the wall is exponentially smaller than the central plasma density for strong centrifugal confinement compared to the case of no confinement, for which the neutral wall density equals the central plasma density. The exponential factor is effectively exp(−Ms2∕2), where Ms is the sonic Mach number of the rotation speed. The effective neutral penetration depth along the field, of the same order as the cross-field penetration depth in the zero confinement limit, increases significantly in the strong confinement case. Estimates are given of plasma transverse momentum loss rates for centrifugally confined plasmas from plasma particle outfluxes and charge-exchange friction.
Rotational spectra of rare isotopic species of bromofluoromethane: Determination of the equilibrium structure fromab initiocalculations and microwave spectroscopy
Authors: Puzzarini Cristina , Cazzoli Gabriele , Baldacci Agostino , Baldan Alessandro , Michauk Christine , Gauss Jürgen
Published: October 2007

Guided by theoretical predictions, the rotational spectra of the mono- and bideuterated species of bromofluoromethane, CDHBr79F, CDHBr81F, CD2Br79F, and CD2Br81F, have been recorded for the first time. Assignment of a few hundred rotational transitions led to the accurate determination of the ground-state rotational constants, all of the quartic and most of the sextic centrifugal distortion constants, as well as the full bromine quadrupole-coupling tensor for both Br79 and Br81, in good agreement with corresponding theoretical predictions based on high-level coupled-cluster calculations. The rotational spectra of the C13 containing species C13H2Br79F and C13H2Br81F have been observed in natural abundance and have been assigned, thus allowing the determination of the rotational and centrifugal distortion constants as well as the bromine quadrupole-coupling tensor. Furthermore, empirical equilibrium structures have been obtained within a least-squares fit procedure using the available experimental ground-state rotational constants for various isotopic species. Vibrational effects have been accounted for in the analysis using vibration-rotation interaction constants derived from anharmonic force fields computed at the second-order Møller-Plesset perturbation theory as well as coupled-cluster (CC) levels. The empirical equilibrium geometries obtained in this way agree well with the corresponding theoretical predictions obtained from CC calculations [at the CCSD(T) level] after extrapolation to the complete basis set limit and inclusion of core-valence correlation corrections and relativistic effects.
Low dust charging rate induced weakly dissipative dust acoustic solitary waves: Role of nonthermal ions
Authors: Chaudhuri Tushar Kanti , Khan Manoranjan , Gupta M. R. , Ghosh Samiran
Published: October 2007

The effects of low dust charging rate compared to the dust oscillation frequency and nonthermal ions on small but finite amplitude nonlinear dust acoustic wave have been investigated. It is seen that because of the low dust charging rate, the nonlinear wave exhibits weakly dissipative solitary wave that is governed by a modified form of the Korteweg-de Vries equation. The solitary wave possesses both rarefactive and compressive soliton solution depending on the values of ion nonthermality parameter a. An analytical solution reveals that because of the simultaneous effects of low dust charging rate and nonthermal ions, the wave amplitude may grow exponentially with time if the ion nonthermality parameter (a) exceeds a critical value provided the ion-electron temperature ratio (σi) is less than 0.11.
The influence of Sc addition on the welding microstructure of Zr-based bulk metallic glass: The stability of the amorphous phase
Authors: Wang Shing Hoa , Kuo Pei Hung , Tsang Hsiao Tsung , Jeng Rong Ruey , Lin Yu Lon
Published: October 2007

Pulsed direct current autogeneous tungsten inert gas arc welding was conducted on rods of bulk metallic glasses (BMGs) Zr55Cu30Ni5Al10 and (Zr55Cu30Ni5Al10)99.98Sc0.02 under two different cooling conditions. The crystalline precipitates in the fusion zone of BMG Zr55Cu30Ni5Al10 were confirmed by microfocused x-ray diffraction pattern analysis as Zr2Ni and Zr2(Cu,Al) intermetallic compounds. In contrast, BMG with Sc addition (Zr55Cu30Ni5Al10)99.98Sc0.02 shows an excellent stable glass forming ability. The fusion zone of BMG (Zr55Cu30Ni5Al10)99.98Sc0.02 remains in the same amorphous state as that of the amorphous base metal when the weld is cooled with accelerated cooling.
Experimental transfer of torque induced by localized polarization of radially polarized vector beams to anisotropic microparticles
Authors: Ahluwalia B. P. S. , Yuan X.-C. , Moh K. J. , Bu J.
Published: October 2007

Polarization-induced torque of a radially polarized beam is investigated on anisotropic micro-particles. Radially polarized beams possess full cylindrical symmetry; therefore, any line drawn from the beam axis to the circumference contains identical polarization vectors, acting locally as linearly polarized. It is experimentally observed that anisotropic microparticles experience an aligning torque by the localized segment of the radially polarized beam, setting it to rotate around the beam axis. The rotation of the particle thus enables the mapping of the localized electric vector distribution of radially polarized beams.
Annealing properties of vacancy-type defects in ion-implanted GaN studied by monoenergetic positron beams
Authors: Uedono A. , Ito K. , Nakamori H. , Mori K. , Nakano Y. , Kachi T. , Ishibashi S. , Ohdaira T. , Suzuki R.
Published: October 2007

Defects in ion-implanted GaN and their annealing properties were studied by using monoenergetic positron beams. Doppler broadening spectra of the annihilation radiation and the positron lifetimes were measured for Si+, O+, and Be+-implanted GaN grown by the metal-organic chemical vapor deposition technique. First-principles calculations were also used to identify defect species introduced by the implantation. For as-implanted samples, the major defect species was identified as Ga vacancies and/or divacancies. An agglomeration of defects starts after annealing at 400 °C, and the defect profile shifted toward the surface with the open volumes of the defects increasing. The annealing properties of defects were found to depend on the ion species, and they are discussed here in terms of defect concentrations and interactions between impurities and defects.
Interfacial friction obtained by lateral manipulation of nanoparticles using atomic force microscopy techniques
Authors: Dietzel Dirk , Mönninghoff Tristan , Jansen Lars , Fuchs Harald , Ritter Claudia , Schwarz Udo D. , Schirmeisen André
Published: October 2007

Nanometer scale metallic particles have been manipulated on an atomically flat graphite surface by atomic force microscopy techniques and quantitative information on interfacial friction was extracted from the lateral manipulation of these nanoparticles. Similar to conventional friction force microscopy, the particle-surface interfacial friction was extracted from the torsional signal of the cantilever during the particle pushing process. As a model system, we chose antimony particles with diameters between 50 and 500nm grown on a highly oriented pyrolytic graphite substrate. Three different manipulation strategies have been developed, which either enable the defined manipulation of individual nanoparticles or can be utilized to gather data on a larger number of particles found within a particular scan area, allowing for fast and statistically significant data collection. While the manipulation strategies are demonstrated here for operation under vacuum conditions, extensive testing indicated that the proposed methods are likewise suited for ambient environments. Since these techniques can be applied to a large variety of chemically and structurally different material combinations as well as a large range of particle sizes, our results indicate a viable route to solve many recent issues in the field of nanoscale friction, such as the influence of contact size and interface crystallinity.
Behavior of hydrogen in wide band gap oxides
Authors: Xiong K. , Robertson J. , Clark S. J.
Published: October 2007

The energy levels of interstitial hydrogen in various wide band gap oxides are calculated using a density function based method that does not need a band gap correction. The positive charge state has a large stabilization energy due to the formation of an O–H bond. The hydrogen level is found to be shallow in CdO, ZrO2, HfO2, La2O3, LaAlO3, SnO2, TiO2, SrTiO3, PbTiO3, and SrBi2Ta2O9, but deep in MgO, Al2O3, SiO2, ZrSiO4, HfSiO4, and SrZrO3. It is borderline in SrO. The predictions are found to agree well with the experimental behavior of muonium in these oxides.
Propagation of laser filaments through an extended turbulent region
Authors: Salamé R. , Lascoux N. , Salmon E. , Ackermann R. , Kasparian J. , Wolf J.-P.
Published: October 2007

We show that laser filamentation can be initiated and propagate through strong extended turbulence well above the typical atmospheric values. We suggest that the effect of turbulence on filamentation is characterized by the product of the structure parameter for the refractive index Cn2 and the length L of the turbulence region. Half of the filaments are transmitted for Cn2L⩽4.4×10−10m1∕3. Moreover, the surviving filaments keep their key spectral properties including correlations inside the white-light continuum.
Structural and cathodoluminescence assessment of V2O5 nanowires and nanotips grown by thermal deposition
Authors: Díaz-Guerra C. , Piqueras J.
Published: October 2007

V 2 O 5 nanostructures have been grown on 4H-SiC and Si substrates by a thermal deposition method without a catalyst. High aspect ratio nanowires with rectangular cross sections were grown on 4H-SiC. High-resolution transmission electron microscopy observations and cathodoluminescence (CL) spectroscopy measurements reveal the high crystal quality of the grown nanowires. Deposition on Si substrates leads to the growth of V2O5 platelets or rod-shaped crystals ending in arrays of parallel sharp nanotips with apex radius in the 50 nm range. A CL emission band observed centered at about 1.70 eV in spectra from these nanostructures is tentatively attributed to defect centers involving oxygen vacancies.
A dynamical approximation for stochastic partial differential equations
Authors: Wang Wei , Duan Jinqiao
Published: October 2007

Random invariant manifolds provide geometric structures for understanding stochastic dynamics. In this paper, a dynamical approximation estimate is derived for a class of stochastic partial differential equations, by showing that the random invariant manifold is almost surely asymptotically complete. The asymptotic dynamical behavior is thus described by a stochastic ordinary differential system on the random invariant manifold, under suitable conditions. As an application, stationary states (invariant measures) are considered for a class of stochastic hyperbolic partial differential equations.