bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality of residual oil from palm‐pressed mesocarp fiber (Elaeis guineensis) using supercritical CO2 with and without ethanol
Authors: Lau Harrison Lik Nang , Choo Yuen May , Ma Ah Ngan , Chuah Cheng Hock
Published: February 2007

The qualities of oils extracted from fresh and dried palm‐pressed mesocarp fiber were evaluated. The means of extraction included conventional solvent extraction and supercritical carbon dioxide (SC‐CO2) extraction with and without addition of ethanol. Extraction efficiency using pure SC‐CO2 and the effect of moisture content on efficiency were studied. Minor components, such as vitamin F, carotenoids, squalene and phytosterols, obtained by different methods were compared. The quality of oil recovered from fresh palm‐pressed fiber is generally better than that of oil recovered from dried fiber. The SC‐CO2 extraction rate was lower for fresh fiber than for dried fiber. The incorporation of ethanol with SC‐CO2 resulted in oil with higher oxidative stability than did SC‐CO2 alone. Concentrations of minor components and the acylglycerol compositions of the oils extracted from both types of fibers were similar.
Circulating (cell‐free) nucleic acids – A promising, non‐invasive tool for early detection of several human diseases
Authors: Swarup Vishnu , Rajeswari M.R.
Published: February 2007

Circulating nucleic acids (CNA) are present in small amounts in the plasma of healthy individuals. However, increased levels of plasma CNA have been reported in a number of clinical disorders like cancer, stroke, trauma, myocardial infarction, autoimmune disorders, and pregnancy‐associated complications. CNA has received special attention because of its potential application as a non‐invasive, rapid and sensitive tool for molecular diagnosis and monitoring of acute pathologies and the prenatal diagnosis of fetal genetic diseases. This review throws light on the current status of blood CNA as a diagnostic marker and its potential as a powerful tool in the future.
β‐Catenin regulates P‐cadherin expression in mammary basal epithelial cells
Authors: Faraldo Marisa M. , Teulière Jérôme , Deugnier Marie-Ange , Birchmeier Walter , Huelsken Joerg , Thiery Jean Paul , Cano Amparo , Glukhova Marina A.
Published: February 2007

P‐cadherin expression is restricted to the basal layer of stratified epithelia including that of the mammary gland. Although evidence for an important role of P‐cadherin in mammary morphogenesis and tumorigenesis is increasing, the mechanisms that regulate its expression are poorly understood. We show that in basal mammary epithelial cells, β‐catenin is associated with the P‐cadherin promoter and activates its expression independently of LEF/TCF in a cell‐type specific manner. Down‐regulation of endogenous β‐catenin levels by RNA interference technique inhibited P‐cadherin promoter activity. In vivo, in skin and mammary gland of mutant mice, activation of β‐catenin signalling correlates with up‐regulation of P‐cadherin expression. These data suggest that β‐catenin‐dependent modulation of P‐cadherin expression can contribute to the establishment of the basal phenotype.
Analysis of acidic surface of Haloferax mediterranei glucose dehydrogenase by site‐directed mutagenesis
Authors: Esclapez J. , Pire C. , Bautista V. , Martínez-Espinosa R.M. , Ferrer J. , Bonete M.J.
Published: February 2007

Generally, halophilic enzymes present a characteristic amino acid composition, showing an increase in the content of acidic residues and a decrease in the content of basic residues, particularly lysines. The latter decrease appears to be responsible for a reduction in the proportion of solvent‐exposed hydrophobic surface. This role was investigated by site‐directed mutagenesis of glucose dehydrogenase from Haloferax mediterranei, in which surface aspartic residues were changed to lysine residues. From the biochemical analysis of the mutant proteins, it is concluded that the replacement of the aspartic residues by lysines results in slightly less halotolerant proteins, although they retain the same enzymatic activities and kinetic parameters compared to the wild type enzyme.
The Krüppel‐like zinc finger protein Glis2 functions as a negative modulator of the Wnt/β‐catenin signaling pathway
Authors: Kim Yong-Sik , Kang Hong Soon , Jetten Anton M.
Published: February 2007

To gain insight into the mechanism by which Gli‐similar 2 (Glis2) regulates transcription, we performed yeast‐two hybrid cDNA library screening using Glis2 as bait. This screening identified β‐catenin as a potential Glis2‐interacting protein. Mammalian two‐hybrid, co‐immunoprecipitation, and GST‐pulldown analyses supported the interaction between Glis2 and β‐catenin. Pulldown analyses with several Glis2 deletion mutants indicated that the 1st zinc finger motif of Glis2 is critical for its interaction with β‐catenin, while the armadillo repeats of β‐catenin are important in its interaction with Glis2. Reporter analyses showed that Glis2 represses T‐cell factor (TCF)‐mediated transcriptional activation. In addition, Glis2 represses the expression of the TCF target gene cyclin D1. Our results indicate that Glis2 interacts with β‐catenin and suggest that Glis2 functions as a negative modulator of β‐catenin/TCF‐mediated transcription.
Surfactin from Bacillus subtilis displays anti‐proliferative effect via apoptosis induction, cell cycle arrest and survival signaling suppression
Authors: Kim Seo-young , Kim Joo Young , Kim Seol-Hee , Bae Hyun Jin , Yi Hwaseon , Yoon Sang Hong , Koo Bon Sung , Kwon Moosik , Cho Jae Youl , Lee Choong-Eun , Hong Sungyoul
Published: February 2007

The effect of surfactin on the proliferation of LoVo cells, a human colon carcinoma cell line, was examined. Surfactin strongly blocked the proliferation of LoVo cells by inducing pro‐apoptotic activity and arresting the cell cycle, according to several lines of evidence on DNA fragmentation, Annexin V staining, and altered levels of poly (ADP‐ribose) polymerase, caspase‐3, p21WAF1/Cip1, p53, CDK2 and cyclin E. The anti‐proliferative activity of surfactin was mediated by inhibiting extracellular‐related protein kinase and phosphoinositide 3‐kinase/Akt activation, as assessed by phosphorylation levels. Therefore, our data suggest that surfactin may have anti‐cancer properties as a result of its ability to downregulate the cell cycle and suppress its survival.
TRANSIENT BONE LOSS OF DISTAL RADIUS AND ULNA FOLLOWING CLEAN-CUT TENDON INJURIES, REPAIR AND PASSIVE MOBILISATION
Authors: KEKILLI E. , ERTEM K. , YAGMUR C. , ATASEVER A. , ELMALI N. , CEYLAN F.
Published: February 2007

The aim of this study was to investigate whether there is any significant bone loss of the ulna and radius following acute tendon-artery-nerve clean-cut injuries at the wrist level which were repaired and rehabilitated by early passive mobilisation. Fifty-eight patients who underwent such operation were enrolled in this study. Patients in Group I ( n = 28) had primary tendon repairs alone, in Group II ( n = 15) primary tendon and nerve repairs and in Group III ( n = 15) primary tendon, nerve and artery repairs. Bone mineral density (BMD) measurements of the ulna and radius were obtained during the first week, the sixth week, the third month and the 12th month after operation. The results demonstrated that BMD decrease in the ulna was more common than in the radius. When compared with the first week BMD measurements, the highest reduction was seen in the sixth week in Group I and during the third month, when bone loss of both the radius and ulna was considerable in Group II. The bone loss in all groups and subgroups were found to have recovered at the 12th month measurements, except in the distal region of the ulna in Group I. This study suggests that passive immobilisation is deleterious in respect of demineralisation of the forearm bones.
Roughness-induced flow instability: a lattice Boltzmann study
Authors: VARNIK FATHOLLAH , DORNER DOROTHÉE , RAABE DIERK
Published: February 2007

Effects of wall roughness/topography on flows in strongly confined (micro-)channels are studied by means of lattice Boltzmann simulations. Whereas wall roughness in macroscopic channels is considered to be relevant only for high-Reynolds-number turbulent flows (where the flow is turbulent even for smooth walls), it is shown in this paper that, in micro-channels, surface roughness may even modify qualitative features of the flow. In particular, a transition from laminar to unsteady flow is observed. It is found that this roughness-induced transition is strongly enhanced as the channel width is decreased. The reliability of our results is checked by computing the viscous shear stress and the Reynolds stress across the channel, their sum following the theoretical prediction for the stress balance perfectly. Furthermore, the solutions obtained obey the transformation rules of the Navier–Stokes equation: When expressed in reduced (dimensionless) units, results for various channel dimensions, forcing term or dynamic viscosity are identical provided that the channel shape and the Reynolds number are unchanged. The time evolution of the velocity fluctuations at the initial stages of the transition to flow instability is monitored. It is found that fluctuations first occur in the vicinity of the rough wall, supporting the interpretation of wall roughness as a source of fluctuations and thus flow instability. In addition to their physical significance, our results provide further evidence for the reliability of the lattice Boltzmann method in dealing with complex unsteady flows.
Hydraulic jumps due to oblique impingement of circular liquid jets on a flat horizontal surface
Authors: KATE R. P. , DAS P. K. , CHAKRABORTY SUMAN
Published: February 2007

An obliquely inclined circular water jet, impinging on a flat horizontal surface, confers a series of hydraulic jump profiles, pertaining to different jet inclinations and jet velocities. These jump profiles are non-circular, and can be broadly grouped into two categories, based on the angle of jet inclination, φ, made with horizontal. Jumps corrosponding to the range (25° < φ≤ 90°) are observed to be bounded by smooth curves, whereas those corresponding to φ≤ 25° are characterized by distinct corners. The present work attempts to find a geometric and hydrodynamic characterization of the spatial patterns formed as a consequence of such non-circular hydraulic jump profiles. Flow-visualization experiments are conducted to depict the shape of demarcating boundaries between supercritical and subcritical flows, and the corresponding radial jump locations are obtained. Theoretical calculations are also executed to obtain the radial locations of the jumps with geometrically smooth profiles. Comparisons are subsequently made between the theoretical predictions and the experimental observations, and a good agreement between these two can be observed. Jumps with corners, however, turn out to be comprised of strikingly contrasting profiles, which can be attributed to the ‘jump–jet’ interaction and the ‘jump-jump’ interaction mechanisms. A phenomenological explanation is also provided, by drawing an analogy from the theory of shock-wave interactions.
Suppression of vortex shedding behind a circular cylinder by another control cylinder at low Reynolds numbers
Authors: DIPANKAR A. , SENGUPTA T. K. , TALLA S. B.
Published: February 2007

Vortex shedding behind a cylinder can be controlled by placing another small cylinder behind it, at low Reynolds numbers. This has been demonstrated experimentally by Strykowski & Sreenivasan (J. Fluid Mech. vol. 218, 1990, p. 74). These authors also provided preliminary numerical results, modelling the control cylinder by the innovative application of boundary conditions on some selective nodes. There are no other computational and theoretical studies that have explored the physical mechanism. In the present work, using an over-set grid method, we report and verify numerically the experimental results for flow past a pair of cylinders. Apart from providing an accurate solution of the Navier–Stokes equation, we also employ an energy-based receptivity analysis method to discuss some aspects of the physical mechanism behind vortex shedding and its control. These results are compared with the flow picture developed using a dynamical system approach based on the proper orthogonal decomposition (POD) technique.
Can the 12-item General Health Questionnaire be used to measure positive mental health?
Authors: HU YONGJIAN , STEWART-BROWN SARAH , TWIGG LIZ , WEICH SCOTT
Published: February 2007

Background. Well-being is an important determinant of health and social outcomes. Measures of positive mental health states are needed for population-based research. The 12-item General Health Questionnaire (GHQ-12) has been widely used in many settings and languages, and includes positively and negatively worded items. Our aim was to test the hypothesis that the GHQ-12 assesses both positive and negative mental health and that these domains are independent of one another.

Method. Exploratory (EFA) and confirmatory (CFA) factor analyses were conducted using data from the British Household Panel Survey (BHPS) and the Health Survey for England (HSE). Regression models were used to assess whether associations with individual and household characteristics varied across positive and negative mental health dimensions. We also explored higher-level variance in these measures, between electoral wards.

Results. We found a consistent, replicable factor structure in both datasets. EFA results indicated a two-factor solution, and CFA demonstrated that this was superior to a one-factor model. These factors correspond to ‘symptoms of mental disorder’ and ‘positive mental health’. Further analyses demonstrated independence of these factors in associations with age, gender, employment status, poor housing and household composition. Statistically significant ward-level variance was found for symptoms of mental disorder but not positive mental health.

Conclusions. The GHQ-12 measures both positive and negative aspects of mental health, and although correlated, these dimensions have some independence. The GHQ-12 could be used to measure positive mental health in population-based research.
The bacteriology of pneumonia diagnosed in Western Australian emergency departments
Authors: INGARFIELD S. L. , CELENZA A. , JACOBS I. G. , RILEY T. V.
Published: February 2007

We used Western Australian emergency department data linked to hospital morbidity, death and microbiology data to describe the bacteriology of pneumonia according to age. The ‘atypical’ organisms and viruses were not assessed. A total of 6908 patients over a 3-year period were given an emergency department diagnosis of pneumonia, 76·9% were admitted and 6·3% died in hospital. Blood was cultured from 52·9% of patients with 6·4% growing potential pathogens. Streptococcus pneumoniae was the most common organism isolated and accounted for 92% of pathogens in those aged <15 years. Isolation of Enterobacteriaceae species tended to increase with age and accounted for around 25% of isolates from the elderly. Sputum was cultured from 25·3% of patients and bacteria were isolated from 30·3% of samples, commonly Haemophilus influenzae and S. pneumoniae. Isolates from sputum showed no distinct trend across age groups. These patterns question the value of routine blood and sputum cultures and have implications for empiric therapy for the elderly.
Myth, Style, Substance and the Totalitarian Dynamic in Fascist Italy
Authors: ROBERTS DAVID D.
Published: February 2007

Recent studies of Italian Fascism have focused on ritual, spectacle, commemoration and myth, even as they also take seriously the totalitarian thrust of Fascism. But whereas this new culturalist orientation has usefully pointed beyond earlier reductionist approaches, it has often accented style and myth as opposed to their opposites, which might be summed up as ‘substance’. Some of the aspirations fuelling Fascism, responding to perceived inadequacies in the mainstream liberal and Marxist traditions, pointed beyond myth and style as they helped to shape the Fascist self-understanding – and Fascist practice. This article seeks to show how the interplay of substance, style and myth produced a particular – and deeply flawed – totalitarian dynamic in Fascist Italy.
Sippenhaft, Terror and Fear in Nazi Germany: Examining One Facet of Terror in the Aftermath of the Plot of 20 July 1944
Authors: LOEFFEL ROBERT
Published: February 2007

The methods used by the Nazis to control elements of German society have been the focus of intense historical debate. This paper attempts to analyse the implementation ofSippenhaft(family liability punishment) after the 20 July 1944 assassination plot against Hitler.Sippenhaftwas advocated for use against the families of the conspirators involved in this plot and also against members of the armed services. Consequently, its implementation became the personal domain of the Reich leader of the SS, Heinrich Himmler, as well as local army commanders, army courts and the Nazi party itself. This article will argue that the inadequacies of its imposition were largely compensated for by its effectiveness as a device of fear.
PREMATURE CERVICAL CHANGE AND THE USE OF CERVICAL CERCLAGE
Authors: CHANDIRAMANI MANJU , SHENNAN ANDREW H
Published: February 2007

Preterm birth and its subsequent consequences continue to be a major challenge worldwide. In the United States in 2004, 12.5% of infants were born preterm, making the annual societal economic burden associated with preterm birth in excess of $26.2 billion (and this is a modest estimate). Spontaneous preterm birth accounts for about 75% of all preterm births; however, at earlier gestations iatrogenic preterm birth accounts for a greater proportion of all preterm births; at 27–28 weeks 50% are iatrogenic. The proportion of babies transferred to the neonatal unit is more than 90% for those born before 33 completed weeks of gestation compared with 31% at 36 weeks; delivery between 33 completed weeks and 36 completed weeks has a relatively low morbidity and mortality. Nonetheless, 1 in 3 children born preterm but beyond 32 weeks have educational and behavioural problems at the age of 7, with 1 in 4 children born between 32 and 35 weeks requiring support from non-teaching assistants at school. Although more than 40% of babies at 35 completed weeks show signs of maturity, some still need ventilation at 38 completed weeks. Almost one-fifth of all infants born at less than 32 weeks gestation do not survive the first year of life.
Stability of the thermohaline circulation under millennial CO2 forcing and two alternative controls on Atlantic salinity
Authors: Marsh Robert , Hazeleger Wilco , Yool Andrew , Rohling Eelco J.
Published: February 2007

A large ensemble of experiments with an efficient climate model is carried out to examine stability of the oceanic thermohaline circulation (THC) as a function of two key processes that maintain high Atlantic salinities: the “Atmospheric Bridge” by which moisture is exported from the Atlantic to the Pacific; and “Agulhas Leakage” of salty Indian Ocean waters into the Atlantic. We find that irreversible THC collapse during the next millennium is five times more likely if Agulhas Leakage dominates over the Atmospheric Bridge. This finding is consistent with freshwater import to the Atlantic sector associated with the overturning circulation, when the Atmospheric Bridge dominates. In contrast, slight freshwater export is associated with the overturning circulation under strong Agulhas Leakage, helping to maintain higher Atlantic salinity. Predictions of future climate change therefore critically depend on better understanding of the relative importance of the Atmospheric Bridge and Agulhas Leakage.
Adaptation of a model‐generated cloud database to satellite observations
Authors: Seo Eun‐Kyoung , Liu Guosheng , Tao Wei‐Kuo , Han Sang‐Ok
Published: February 2007

Cloud resolving model outputs are often used to build databases for satellite microwave remote sensing of precipitating clouds. A known problem of this approach is that cloud resolving models tend to systematically produce excessive amount of high density frozen hydrometeors, causing the cloud/radiation model database to have stronger scattering signatures at high microwave frequencies than those observed by satellite or airborne sensors. Consequently, it lowers the performance of the cloud and precipitation retrieval algorithms that utilize the model database. Since multi‐frequency satellite observations contain information on hydrometeors' properties, measured brightness temperatures can give guidance as to how the modeled cloud database may be modified to better mimic natural clouds. Following this philosophy, in this study, we propose a method to adapt the modeled database toward observations. The newly constructed database results in a better match to the characteristics of the satellite observed brightness temperatures.
Solar flare induced D region perturbation in the ionosphere, as revealed from a short‐distance VLF propagation path
Authors: Todoroki Y. , Maekawa S. , Yamauchi T. , Horie T. , Hayakawa M.
Published: February 2007

Short‐distance (propagation distance less than 1,000 km) VLF subionospheric propagation is, for the first time, used to study the solar flare induced D‐region perturbations of the lower ionosphere. We have used two years data for a propagation path from the Japanese VLF transmitter (call sign JJI, frequency = 22.2 kHz, and located at Ebino, Kyushu) to a receiving station of Chofu, Tokyo. For the sake of comparison, we have also used the long distance VLF path (NWC‐Chofu). First of all, the value of perturbation in amplitude (ΔA) for the short‐distance path seems to be much more enhanced (ΔA = 8∼9 dB) for this short‐path than the long‐distance paths previously studied. The experimental value of ΔA is found to monotonically increase with the logarithm of X‐ray flux. This dependence is numerically simulated by means of the FDTD (finite difference time domain) method to deduce the D‐region perturbation, {1 + C exp {−(z − z0)2/2β2} (C: enhancement factor, z0: reference height and β: vertical extent) (this modification seems to be much more realistic than the previous two parameter modeling in an exponential profile). The numerical computations with z0 ∼60 km and β ∼ 10 km have shown that the value of ΔA increase up to ∼6 dB in a range of X‐ray flux from C = 10 to C = 103. As the conclusion, the ΔA is closely related with the logarithm of solar X‐ray flux, so that we will be able to deduce the C value from the observed ΔA value.
Predicting wind field in the Bay of Bengal from scatterometer observations using genetic algorithm
Authors: Sharma Rashmi , Sarkar Abhijit , Agarwal Neeraj , Kumar Raj , Basu Sujit
Published: February 2007

A technique based on genetic algorithm (GA) is applied for predicting wind field in the Bay of Bengal (BOB) using satellite scatterometer observations. Empirical orthogonal function (EOF) analysis is used for compressing the spatial variability into a set of eigenmodes. The time series of each principal component (PC) is subjected to singular spectrum analysis (SSA) and GA is applied to the resulting filtered time series. The forecast PCs are weighted by the spatial eigenmodes for computing forecast wind fields. Predictions made up to 5 days in advance are found to be superior to forecast by persistence method.
Computer simulation of chorus wave generation in the Earth's inner magnetosphere
Authors: Katoh Yuto , Omura Yoshiharu
Published: February 2007

A self‐consistent particle simulation with a dipole magnetic field model is carried out, reproducing chorus emissions with rising tones successfully. We assume energetic electrons forming a highly anisotropic velocity distribution in the equatorial region. No initial wave is assumed except for electromagnetic thermal noise induced by the energetic electrons. In the early stage of the simulation, coherent whistler‐mode waves are generated from the equator through an instability driven by the temperature anisotropy of the energetic electrons. During the propagation of the whistler‐mode waves, we find formation of a narrowband emission with negative frequency gradient (NEWNFG) in the spatial distribution of the frequency spectrum in the simulation system. The trailing edge of NEWNFG is continuously created at increasing frequencies in the region close to the equator. Observed at a fixed point, the NEWNFG shows a frequency variation of a typical chorus emission.
Effect of stratification due to suspended sand on velocity and concentration distribution in unidirectional flows
Authors: Herrmann Marine J. , Madsen Ole S.
Published: February 2007

Sediment‐induced stratification effects on velocity profiles and sediment concentration distribution in a steady, uniform turbulent flow are examined in this paper. The early work concerning sediment stratification relates this to the von Karman constant's variability. Subsequent attempts to account for stratification were based on the stratified flow analogy, introducing the parameters α and β, whose values were assumed to be those obtained for thermally stratified flows. Following these investigators, we assume stratification effects to be expressed through these parameters. We solve the governing equations for velocity and sediment concentration for a parabolic neutral eddy viscosity model. Analytically closed‐form solutions are obtained. We run our model against experimental data to obtain the optimal set [α, β]. For neutral conditions, β = 0 by definition, and we obtain α = 1. For stratified conditions we obtain [α = 0.8, β = 4.0]. This is the first time both α and β have been obtained from sediment‐laden flow observations. Accounting for stratification improves the prediction of velocity and concentration. For predictive purposes, we need to know the movable bed roughness and the reference concentration. Analyses of experimental data sets provide predictive relationships for these in terms of sediment and flow parameters.
Formation of a sandy near‐bed transport layer from a fine‐grained bed under oscillatory flow
Authors: Liang Hanzhuang , Lamb Michael P. , Parsons Jeffrey D.
Published: February 2007

Bed surface coarsening was found to be an important effect for the formation of ripples and the dynamics of the boundary layer above a predominantly silt‐sized sediment bed (median particle size equal to 26 μm; ∼20% fine sand, 70% silt, 10% clay) under oscillatory flow (with orbital velocities of 0.32–0.52 m/s) in a laboratory wave duct. Following bed liquefaction, substantial winnowing of the bed surface occurred due to entrainment of finer material into suspension. Bed surface coarsening was quantified with micro‐scale visualization using a CCD (charged‐coupled device) camera. Under most wave orbital velocities investigated, the coarse surface particles were mobilized as a near‐bed transport layer approximately 4 grain‐diameters thick. The transport of these coarse sediments ultimately produced suborbital or anorbital ripples on the bed, except for the highest orbital velocities considered where the bed was planar. Micro‐scale visualizations were used to construct a maximum (particle) velocity profile extending through the near‐bed transport layers using particle‐streak velocimetry (PSV). These profiles had a distinctive kink in log linear space at the height of the transport layer, suggesting that the near‐bed sediment transport reduced skin friction and contributed to the boundary roughness through extraction of momentum.
Weibull parameters of Yakuno basalt targets used in documented high‐velocity impact experiments
Authors: Nakamura Akiko M. , Michel Patrick , Setoh Masato
Published: February 2007

In this paper we describe our measurements of the Weibull parameters of a specific basalt material, called Yakuno basalt, which was used in documented high‐velocity impact experiments. The outcomes of these experiments have been widely used to validate numerical codes of fragmentation developed in the context of planetary science. However, the distribution of incipient flaws in the targets, usually characterized by the Weibull parameters, has generally been implemented in the codes with values allowing to match the experimental outcomes; hence the validity of numerical simulations remains to be assessed with the actual values of these parameters from laboratory measurements. Here we follow the original method proposed by Weibull in 1939 to measure these parameters for this Yakuno basalt. We obtain a value of the Weibull modulus (also called shape parameter) m in the range 15–17 with a typical error of about 1.0 for each different trial. This value is larger than the one corresponding to simulation fits to the experimental data, generally around 9.5. The characteristic strength, which corresponds to 63.2% of failure of a sample of similar specimens and which defines the second Weibull or scale parameter, is estimated to be 19.3–19.4 MPa with a typical error of about 0.05 MPa. This parameter seems to not be sensitive to the different loading rates used to make the measurements. A complete database of impact experiments on basalt targets, including both the important initial target parameters and the detailed outcome of their disruptions, is now at the disposal of numerical codes of fragmentation for validity test.
Limitation of the transport capacity approach in sediment transport modeling
Authors: Sander G. C. , Parlange J.‐Y. , Barry D. A. , Parlange M. B. , Hogarth W. L.
Published: February 2007

In a recent paper by Polyakov and Nearing (2003) it was shown experimentally that the sediment transport capacity in a rill is not unique for a given soil type, slope, and flow rate. Indeed, they found that the transport capacity was dependent on whether sediment transport in the rill was occurring under net erosion or net deposition conditions. They concluded that this nonuniqueness in transport capacity is a discrepancy that needs addressing in soil erosion models. Here we postulate that this behavior occurs as a result of defining transport capacity as an model input to distinguish between net erosion and net deposition regimes, instead of determining it as an outcome between the separate but continuous rate processes of deposition and entrainment such as is the case for the multisize class erosion model of Hairsine and Rose (1992a, 1992b). This model is used to reinterpret and reproduce the results of Polyakov and Nearing (2003). The analysis shows that the transport capacity cannot be unique for a soil composed of a range of size classes and that uniqueness only occurs for the exceptional case of single size class soil. Consequently, when used as a model input, the transport capacity concept is deficient in modeling sediment transport of real soils across different flow conditions.
A Key to the Tables
Authors: Alexander S. P. H. , Mathie A , Peters J. A.
Published: February 2007

ALEXANDER, S.P.H., MATHIE, A. & PETERS, J.A. (2007). Guide to Receptors and Channels (GRAC), 2nd edition (2007 revision). Br. J. Pharmacol., 150 (Suppl. 1), S1–S168.
Ion Channels
Authors: Alexander S. P. H. , Mathie A , Peters J. A.
Published: February 2007

ALEXANDER, S.P.H., MATHIE, A. & PETERS, J.A. (2007). Guide to Receptors and Channels (GRAC), 2nd edition (2007 revision). Br. J. Pharmacol., 150 (Suppl. 1), S1–S168.
The origin of convective structures in the scrape-off layer of linear magnetic fusion devices investigated by fast imaging
Authors: Antar G. Y. , Yu J. H. , Tynan G.
Published: February 2007

A fast imaging camera is used to unveil the spatio-temporal properties of radially convective events in the CSDX linear plasma device [M. J. Burin et al., Phys. Plasmas, 12, 052320 (2005)]. The exposure time is set to 1μs and the time between frames to 10μs. The time series from a Langmuir probe and from a pixel in the 50000-frame movie are compared and cross-correlated. Excellent agreement between the two diagnostics is found for spatial scales greater than 2.5mm. The fluctuations inside the main plasma column are found to change between different poloidal mode numbers as a function of time. Accordingly, the power spectra determined in these linear devices reflect the sum over these modes. Outside the main plasma column, avaloids are observed to remain attached to the main plasma, hence their behavior does not become independent of the dynamics inside the main plasma column. Avaloid properties, assessed from imaging, agree with Langmuir probes done on various devices, except that the radial length is found to be much larger than previously determined because the blob-shape assumption is not valid. The link between fluctuations inside and outside the main plasma column indicates that the nonlinear evolution of the m=1 poloidal mode number is responsible for the creation of avaloids.
Energy landscapes for water clusters in a uniform electric field
Authors: James Tim , Wales David J. , Hernández Rojas Javier
Published: February 2007

The behavior of small water clusters, (H2O)n, n=2–5 and n=8, in a uniform electric field is investigated for three related rigid-body models. Changes in the properties of the low-lying potential energy minima and the rearrangement pathways between them are examined. Results for certain structural transitions are compared with recent ab initio calculations. The models are found to give qualitatively similar trends, and there is some evidence that as the applied field strength is increased the quantitative differences between the models are also reduced.
Theoretical investigation of exchange and recombination reactions in O(P3)+NO(Π2) collisions
Authors: Ivanov M. V. , Zhu H. , Schinke R.
Published: February 2007

We present a detailed dynamical study of the kinetics of O(P3)+NO(Π2) collisions including O atom exchange reactions and the recombination of NO2. The classical trajectory calculations are performed on the lowest A′2 and A″2 potential energy surfaces, which were calculated by ab initio methods. The calculated room temperature exchange reaction rate coefficient, kex, is in very good agreement with the measured one. The high-pressure recombination rate coefficient, which is given by the formation rate coefficient and to a good approximation equals 2kex, overestimates the experimental data by merely 20%. The pressure dependence of the recombination rate, kr, is described within the strong-collision model by assigning a stabilization probability to each individual trajectory. The measured falloff curve is well reproduced over five orders of magnitude by a single parameter, i.e., the strong-collision stabilization frequency. The calculations also yield the correct temperature dependence, kr∝T−1.5, of the low-pressure recombination rate coefficient. The dependence of the rate coefficients on the oxygen isotopes are investigated by incorporating the difference of the zero-point energies between the reactant and product NO radicals, ΔZPE, into the potential energy surface. Similar isotope effects as for ozone are predicted for both the exchange reaction and the recombination. Finally, we estimate that the chaperon mechanism is not important for the recombination of NO2, which is in accord with the overall T−1.4 dependence of the measured recombination rate even in the low temperature range.
Europium luminescence enhancement in Al2O3:Eu3+ powders prepared by direct combustion synthesis
Authors: Rakov Nikifor , Maciel Glauco S. , B. Whualkuer Lozano , de Araújo Cid B.
Published: February 2007

The luminescence properties of Eu3+:Al2O3 powders prepared via low temperature direct combustion synthesis was investigated. It was observed that the heat treatment of the powders modifies the dynamics of the radiative transition D05→F27 of Eu3+ (1.0mol%) and produces an enhancement of the luminescence intensity by nearly one order of magnitude. The luminescence enhancement is attributed to the presence of Eu3+ in α-Al2O3 crystalline phase as the heat treatment drastically reduces the amount of amorphous Al2O3 phases present in the powder.
Three-dimensional atom probe studies of an InxGa1−xN∕GaN multiple quantum well structure: Assessment of possible indium clustering
Authors: Galtrey Mark J. , Oliver Rachel A. , Kappers Menno J. , Humphreys Colin J. , Stokes Debbie J. , Clifton Peter H. , Cerezo Alfred
Published: February 2007

An InxGa1−xN∕GaN multiple quantum well (MQW) structure that exhibited bright photoluminescence was examined with the three-dimensional atom probe. The quantum wells were clearly imaged and the indium fraction x measured to be 0.19±0.01, in good agreement with x-ray diffraction measurements. The distribution of indium in the MQWs was analyzed: no evidence for either high indium concentration regions or indium clustering was found, in contrast with many of the transmission electron microscopy studies in the literature. The authors conclude that indium clustering is not necessary for bright luminescence in InGaN.
Modeling of a square pulsed capillary discharge waveguide for interferometry measurements
Authors: Broks B. H. P. , Van Dijk W. , van der Mullen J. J. A. W. , Gonsalves A. J. , Rowlands-Rees T. P. , Hooker S. M.
Published: February 2007

Slow pulsed capillary discharges in round capillaries are currently under investigation for use as plasma channel laser waveguides in laser-wakefield acceleration, x-ray lasers, and higher-harmonic generation. In this study, a capillary discharge with a square cross section is presented. The electron density, which determines the laser guiding properties, can be measured by means of transverse interferometry in this device. Using a numerical model of the plasma and the capillary wall, an analysis of the discharge is made. The results predict that the square channel is capable of guiding circular laser pulses. The guiding properties are quite similar to those of a round channel with nearly the same diameter as the channel width. This suggests the results obtained by measuring the square capillary discharge are applicable for round channels as well. It was found that the wall heating was inhomogeneous, which makes the wall more susceptible to ablation. The heating of the wall changes the transverse optical pathlength in the interferometry experiments.
Monte Carlo calculation of two-dimensional electron gas mobility in InN-based heterostructures
Authors: Polyakov V. M. , Schwierz F.
Published: February 2007

We present a theoretical study of the low-field mobility of two-dimensional electron gases (2DEGs) formed in gated In0.05Ga0.95N∕InN heterostructures using the ensemble Monte Carlo method. The main emphasis is given to investigate the dependence of the mobility on the electron sheet density which can be effectively controlled by a variation of the gate bias. The major scattering mechanisms such as Coulomb scattering related to the presence of charged threading dislocations and ionized impurities, interface roughness, and phonon scatterings are included in the Monte Carlo calculations. Relative contributions from individual scattering mechanisms to the 2DEG mobility depending on temperature, dislocation concentration, and electron sheet density are discussed. It was found, that charged threading dislocations with concentrations in excess of 108cm−2 are the major limitation of the two-dimensional electron mobility at low temperatures and low sheet densities of the 2DEG. However, when by a positive gate bias the electron distribution is pushed closer to the interface (high electron sheet density regime), interface roughness scattering becomes the dominant scattering mechanism and the mobility drastically decreases. The room temperature 2DEG mobility, even for an ionized impurity concentration Nimp=1016cm−3, would attain a value as high as 12500cm2∕Vs in case if In0.05Ga0.95N∕InN heterostructures could be grown without dislocations. For dislocation densities ranging from 108to1010cm−2, the room temperature electron mobility varies from about 10000to1000cm2∕Vs, respectively.
Structure, spin dynamics, and magnetic properties of annealed nanoscale Fe layers on GaAs
Authors: Shaw Justin M. , Falco Charles M.
Published: February 2007

We performed a detailed study of the effect of annealing (at temperatures up to 300°C) on 0.2–3.0nm thick epitaxial Fe layers deposited on GaAs(001). Using Brillouin light scattering, we studied the magnetic properties and spin dynamics of these layers and found a strong correlation between magnetic properties and the structure and chemical properties, as measured with electron diffraction, scanning tunneling microscopy, and x-ray photoemission spectroscopy. We found that significant changes in crystallinity and microstructure occur with annealing. Specifically, annealing of the thinnest layers results in the formation of a discontinuous magnetic layer with increased crystal order. At slightly larger thicknesses, faceted pits form in the Fe layer. This change in structure results in an earlier transition to a ferromagnetic phase, the creation of an additional higher frequency spin-wave mode, and a reduction in the magnetic uniaxial anisotropy constant.
Improving sensitivity in electrostatic force detection utilizing cantilever with tailored resonance modes
Authors: Kimura Kenjiro , Kobayashi Kei , Matsushige Kazumi , Yamada Hirofumi
Published: February 2007

In order to increase the sensitivity of potential or capacitance measurement in Kelvin probe force microscopy or scanning capacitance force microscopy, the frequency of alternating electric field applied between the tip and the sample is tuned close to the mechanical resonance frequencies of the cantilever. The authors have designed a cantilever with a tailored resonance modes suitable for these measurements. The ratio of the first and the second resonance frequencies is optimized by the finite element method. Furthermore, they modified a commercially available cantilever according to the calculation. The performance of the modified cantilever was demonstrated in the scanning capacitance force microscopy measurement.
Analysis of plume following ultraviolet laser ablation of doped polymers: Dependence on polymer molecular weight
Authors: Rebollar Esther , Oujja Mohamed , Bounos Giannis , Kolloch Andreas , Georgiou Savas , Castillejo Marta
Published: February 2007

This work investigates the effect of polymer molecular weight MW on the plume characteristics of poly(methyl methacrylate) (PMMA) and polystyrene (PS) films doped with iodonaphthalene (NapI) and iodophenanthrene (PhenI) following irradiation in vacuum at 248nm. Laser-induced fluorescence probing of the plume reveals the presence of ArH products (NapH and PhenH from, respectively, NapI- and PhenI-doped films). While a bimodal translational distribution of these products is observed in all cases, on average, a slower translational distribution is observed in the low MW system. The extent of the observed dependence is reduced as the optical absorption coefficient of the film increases, i.e., in the sequence NapI∕PMMA, PhenI∕PMMA, and PS-doped films. Further confirmation of the bimodal translational distributions is provided by monitoring in situ the temporally resolved attenuation by the plume as it expands in vacuum of a continuous wave helium–neon laser propagating parallel to the substrate. Results are discussed in the framework of the bulk photothermal model, according to which ejection requires that a critical number of bonds are broken.
Reduced Lorenz models for anomalous transport and profile resilience
Authors: Rypdal K. , Garcia O. E.
Published: February 2007

The physical basis for the Lorenz equations for convective cells in stratified fluids, and for magnetized plasmas imbedded in curved magnetic fields, are reexamined with emphasis on anomalous transport. It is shown that the Galerkin truncation leading to the Lorenz equations for the closed boundary problem is incompatible with finite fluxes through the system in the limit of vanishing diffusion. An alternative formulation leading to the Lorenz equations is proposed, invoking open boundaries and the notion of convective streamers and their back-reaction on the profile gradient, giving rise to resilience of the profile. Particular emphasis is put on the diffusionless limit, where these equations reduce to a simple dynamical system depending only on one single forcing parameter. This model is studied numerically, stressing experimentally observable signatures, and some of the perils of dimension-reducing approximations are discussed.
Rotational stabilization in the Boozer model
Authors: Pustovitov V. D.
Published: February 2007

The rotational stabilization of resistive wall modes is analyzed within the single-mode cylindrical model that incorporates the Boozer boundary conditions [A. H. Boozer, Phys. Plasmas 11, 110 (2004)]. The properties implied by this model are elucidated and expressed in terms of the growth rate and toroidal rotation frequency of the mode, which allows easy comparison of the results with experimental observations and predictions of other theories. It is shown that this model predicts the rotational stabilization in the range Cβ<0.5 only, where Cβ≡(β−βnowall)∕(βwall−βnowall) is a measure of the beta gain between the no wall and ideal wall stability limits.
Z-pinch plasma neutron sources
Authors: Velikovich A. L. , Clark R. W. , Davis J. , Chong Y. K. , Deeney C. , Coverdale C. A. , Ruiz C. L. , Cooper G. W. , Nelson A. J. , Franklin J. , Rudakov L. I.
Published: February 2007

A deuterium gas-puff load imploded by a multi-MA current driver from a large initial diameter could be a powerful source of fusion neutrons, a plasma neutron source (PNS). Unlike the beam-target neutrons produced in Z-pinch plasmas in the 1950s and deuterium-fiber experiments in the 1980s, the neutrons generated in deuterium gas-puffs with current levels achieved in recent experiments on the Z facility at Sandia National Laboratories could contain a substantial fraction of thermonuclear origin. For recent deuterium gas-puff shots on Z, our analytic estimates and one- and two-dimensional simulations predict thermal neutron yields ∼3×1013, in fair agreement with the yields recently measured on Z [C. A. Coverdale et al., Phys. Plasmas (to be published)]. It is demonstrated that the hypothesis of a beam-target origin of the observed fusion neutrons implies a very high Z-pinch-driver-to-fast-ions energy transfer efficiency, 5 to 10%, which would make a multi-MA deuterium Z-pinch the most efficient light-ion accelerator. No matter what mechanism is eventually determined to be responsible for generating fusion neutrons in deuterium gas-puff shots on Z, the deuterium neutron yield is shown to scale as Yn∼Im4, where Im is the peak current of the pinch. Theoretical estimates and numerical modeling of deuterium gas-puff implosions demonstrate that the yields of thermonuclear fusion neutrons that can be produced on ZR and the next-generation machines are sufficiently high to make PNS the most powerful, cost- and energy-efficient laboratory sources of 2.5−14MeV fusion neutrons, just like plasma radiation sources are the most powerful sources of soft and keV x rays. In particular, the predicted deuterium-tritium thermal neutron-producing capability of PNS driven by the next-generation ZR and ZX accelerators is ∼5×1016 and ∼1018, respectively.
High-resolution photoelectron spectroscopy of Ge-based HfO2 gate stacks
Authors: Renault O. , Fourdrinier L. , Martinez E. , Clavelier L. , Leroyer C. , Barrett N. , Crotti C.
Published: February 2007

High-resolution photoelectron spectroscopy with synchrotron radiation (energy resolution of 50meV) is used to investigate interfacial properties of Ge∕GeOx (1nm)∕HfO2 (1nm) gate stacks. With soft x rays, a reliable Ge3d core-level study is possible thanks to the much lower cross section of the Hf5p core level than that using AlKα radiation. It is clearly shown that Hf-germanate bonding states are formed at the GeOx∕HfO2 interface, with an additional Ge3d spectral component shifted to lower binding energy relative to GeO2.