bluuebunny/crossref_metadata_2025 huggingface dataset:
The polyvinyl alcohol–bacterial cellulose system as a new nanocomposite for biomedical applications
Authors: Millon L. E. , Wan W. K.
Published: May 2006

Finding materials suitable for soft tissue replacement is an important aspect for medical devices design and fabrication. There is a need to develop a material that will not only display similar mechanical properties as the tissue it is replacing, but also shows improved life span, biocompatibility, nonthrombogenic, and low degree of calcification. Polyvinyl alcohol (PVA) is a hydrophilic biocompatible polymer with various characteristics desired for biomedical applications. PVA can be transformed into a solid hydrogel with good mechanical properties by physical crosslinking, using freeze‐thaw cycles. Hydrophilic bacterial cellulose (BC) fibers of an average diameter of 50 nm are produced by the bacterium Acetobacter xylinum, using a fermentation process. They are used in combination with PVA to form biocompatible nanocomposites. The resulting nanocomposites possess a broad range of mechanical properties and can be made with mechanical properties similar to that of cardiovascular tissues, such as aorta and heart valve leaflets. The stress–strain properties for porcine aorta are matched by at least one type of PVA–BC nanocomposite in both the circumferential and the axial tissue directions. A PVA–BC nanocomposite with similar properties as heart valve tissue is also developed. Relaxation properties of all samples, which are important for cardiovascular applications, were also studied and found to relax at a faster rate and to a lower residual stress than the tissues they might replace. The new PVA–BC composite is a promising material for cardiovascular soft tissue replacement applications. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Real‐time monitoring of the setting reaction of brushite‐forming cement using isothermal differential scanning calorimetry
Authors: Hofmann M. P. , Nazhat S. N. , Gbureck U. , Barralet J. E.
Published: May 2006

The setting behavior of a brushite‐forming cement (β‐tricalcium phosphate/mono calcium monophosphate) was investigated using an indentation technique (the Gillmore needles method) and isothermal differential scanning calorimetry (DSC). The two objectives of the study were to investigate whether DSC could be used to real‐time monitor a fast‐setting calcium phosphate cement (CPC) and to determine if it is possible to correlate DSC results directly with conventional setting‐time measurements. Best‐fit linear correlation analysis revealed that both the initial and final setting time (Ti and Tf) measured by indentation were strongly correlated to the maximum heat flow measured with DSC. It seems therefore possible to predict the setting times, usually achieved with user dependent indentation methods, of this specific fast setting CPC on the basis of objective DSC measurements. The drawbacks of DSC, however, are its overall complexity and expense and the fact that only exothermal reactions can be investigated in comparison to the Gillmore needles method, furthermore, it is not possible to monitor the complete reaction as the first 2 or 3 min are lost due to sample preparation and apparatus set up. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
Removal of noncollagenous components affects dentin bonding
Authors: Pereira P. N. R. , Bedran‐de‐Castro A. K. B. , Duarte W. R. , Yamauchi M.
Published: May 2006

The structural integrity of fibrillar type I collagen is critical for effective dentin bonding. Since most noncollagenous matrix components in dentin are closely associated with collagen, we hypothesized that they may also contribute to dentin bonding. To test this hypothesis, bovine dentin was acid‐etched, treated with chondroitinase ABC (C‐ABC), endo‐β‐galactosidase (Endo‐β), or trypsin. Controls were prepared in the same manner but without the enzymes. All control and experimental specimens were then bonded with One‐Step. Bond strength data were analyzed by one‐way ANOVA and Fisher's PLSD test (p < 0.05). When dentin was treated with C‐ABC or trypsin, bond strengths significantly decreased for the rewetted groups (p < 0.05). The treatment with Endo‐β showed no effects on bond strengths (p > 0.05). When the treated dentin surfaces were observed under SEM, the C‐ABC and trypsin treated groups revealed significant loss of collagen fibril architecture. The results indicate that chondroitin sulfate glycosaminoglycans and trypsin‐digestible noncollagenous proteins play roles in maintaining the open dimensions of the collagen fibril scaffold, which is essential for optimal dentin bonding. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Infiltration/evaporation‐induced shrinkage of demineralized dentin by solvated model adhesives
Authors: Becker Thomas D. , Agee Kelli A. , Joyce Anthony P. , Rueggeberg Frederick A. , Borke James L. , Waller Jennifer L. , Tay Franklin R. , Pashley David H.
Published: May 2006

During dentin bonding, solvated adhesive comonomers are applied to water‐saturated decalcified dentin matrices. When alcohol‐solvated hydrophilic or hydrophobic methacrylate monomers are applied, they chemically remove water and cause matrix shrinkage during comonomer infiltration. Evaporation of solvent induces further shrinkage. The purpose of this work was to compare the shrinkage of water‐saturated dentin matrices infiltrated with ethanol‐ or methanol‐solvated 2‐hydroxyethyl methacrylate (HEMA), 2,2‐bis[4(2‐hydroxy‐3‐methacryloyloxy‐propyloxy)‐phenyl] propane (BisGMA), or triethyleneglycol dimethacrylate (TEGDMA) at 90/10, 70/30, 50/50, and 30/70 mass fraction % alcohol/monomer before and after evaporation of alcohol. Thin (ca 0.2 mm) disks of human mid‐coronal dentin were demineralized and placed in a well beneath the contact probe of a linear variable differential transformer (LVDT). The height of the matrix was measured before and after random application of one of the twelve alcohol/monomer mixtures. Matrix height was measured during infiltration and during solvent evaporation. Between trials, residual monomer was extracted using ethanol. These studies were repeated on specimens in which 100% alcohol was used to substitute for water in the matrix. Both studies revealed that matrices shrink 30–50% but that pretreatment of matrices with alcohol prevents BisGMA phase separations from occurring. Wet bonding with ethanol instead of water permits infiltration of relatively hydrophobic alcohol/monomers. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007
Consequences of work‐home segmentation or integration: a person‐environment fit perspective
Authors: Kreiner Glen E.
Published: May 2006

This study demonstrates how the interaction between an individual's work‐home segmentation preference and the perceived segmentation provided by the workplace affects work‐home conflict (WHC), stress, and job satisfaction. Using a person‐environment (P‐E) fit theoretical base and methodology, data from 325 employees in a wide variety of occupations and organizations illustrate significant fit effects on these outcomes. Results from polynomial regression and response surface methodology highlight important asymmetric effects found in these P‐E fit relationships. By demonstrating the asymmetric results of fit effects, the findings challenge previous research, which has typically advocated an integration of work and home in order to ameliorate role conflict and stress. Copyright © 2006 John Wiley & Sons, Ltd.
Temperature‐related trends in the vertical position of the summer upper tropospheric surface of maximum wind over the Northern Hemisphere
Authors: Strong Courtenay , Davis Robert E.
Published: May 2006

The surface of maximum wind (SMW) is used to examine spatial and temporal variability in the vertical position of jet streams and fast upper tropospheric wind maxima over the Northern Hemisphere (NH) in the NCEP/NCAR Reanalysis for summers 1958–2004. At a given observation time in a gridded data set, the SMW is defined as the surface passing through the fastest analyzed wind above each grid node, with a vertical search domain restricted to the upper troposphere and any tropospheric jet streams extending into the lower stratosphere. The 47‐year mean summer SMW generally resides below the tropopause, undulates in the tropics, and descends poleward in middle and high latitudes. Trends in the pressure of the summer SMW are primarily positive, exceed 30 hPa/decade at some locations, and are found over most of the tropics and subtropics for the period 1958–2004. The thermal wind relationship is used to establish links between the SMW pressure trends and temperature gradient changes in the upper troposphere. The changing temperature gradients are consistent with nonuniform tropospheric warming and are correlated with sea surface temperature (SST) variability related to El Niño and the Pacific Decadal Oscillation. Copyright © 2006 Royal Meteorological Society.
Thin plate smoothing spline interpolation of daily rainfall for New Zealand using a climatological rainfall surface
Authors: Tait Andrew , Henderson Roddy , Turner Richard , Zheng Xiaogu
Published: May 2006

This study presents a method for estimating daily rainfall on a 0.05° latitude/longitude grid covering all of New Zealand for the period 1960–2004 using a second order derivative trivariate thin plate smoothing spline spatial interpolation model. Use of a hand‐drawn (and subsequently digitised) mean annual rainfall surface as an independent variable in the interpolation is shown to reduce the interpolation error compared with using an elevation surface. This result is confirmed when long‐term average annual rainfall data, derived from the daily interpolations, are validated using long‐term river flow data. Copyright © 2006 Royal Meteorological Society
Pollen‐inferred palaeoclimate reconstructions in mountain areas: problems and perspectives
Authors: Ortu Elena , Brewer Simon , Peyron Odile
Published: May 2006

Transfer functions are an efficient tool for the quantitative reconstruction of past climate from low to mid‐elevation pollen sites. However, the application of existing methods to high‐altitude pollen assemblages frequently leads to unrealistic results. In the aim of understanding the causes of these biases, the standard ‘best modern analogue’ method has been applied to two high‐altitude pollen sequences to provide quantitative climate estimates for the Lateglacial and Holocene periods. Both pollen sequences (Laghi dell'Orgials, 2130 m, SW aspect and Lago delle Fate, 2240 m, E aspect) are located in the subalpine belt, on opposing sides of the St. Anna di Vinadio Valley (Italian Maritime Alps). Different results were obtained from the two sequences. The largest differences occurred in palaeotemperature reconstruction, with notable differences in both the values and trends at each site. These biases may be attributed to: (1) a lack of high elevation ‘best modern analogues’ in the database of modern samples; (2) the problem of pollen taxa that have multiple climatic significance; (3) problems related to the complexity of mountainous ecosystems, such as the phenomenon of uphill transport of tree pollen by wind. Possible improvements to the reconstruction process are discussed. Copyright © 2006 John Wiley & Sons, Ltd.
Phptotophysics and kinetics of naphthopyran derivatives, part 4: Investigation of [3H]‐naphthopyran kinetics considered as an ABC(2k, 6ϕ) system yielding a monoexponential trace
Authors: Maafi M. , Brown R. G.
Published: May 2006

The elucidation of [3H]‐naphthopyran photochromic kinetics has been dealt with in this investigation by approximating the photocoloring traces as monoexponential. The experimental data have been analyzed, and 13 defining equations of the reactive dynamics have been established. These have been solved simultaneously as a system of nonlinear equations depending on the extinction coefficients and the six possible quantum yields of this ABC type system. The results of this new approach predict that both colored species are directly photochemically produced from the starting material. The most photochemically reactive photoisomer is the most thermally stable and is also the one characterized by the lowest extinction coefficient of the visible absorption band. The mechanism predicted for 3,3‐diphenyl‐3H‐naphtho[2,1‐b]pyran in toluene at 30°C obeys ABC(1k,6ϕ) kinetics. © 2006 Wiley Periodicals, Inc. J Chem Kinet 38: 431–438, 2006
Role of Star‐Like Hydroxylpropyl Lignin in Soy‐Protein Plastics
Authors: Wei Ming , Fan Lihong , Huang Jin , Chen Yun
Published: May 2006

Summary: Star‐like hydroxypropyl lignin (HL) was compounded into soy protein isolated (SPI) to develop a potential biodegradable plastic with better mechanical performance than pure sheet‐SPI. The structure and properties of the composite materials were characterized by WAXD, DSC, SEM, TEM and tensile tests. The addition of just 2 wt.‐% HL resulted in tensile strength (σb) of 16.8 MPa, 2.3 times that of pure sheet‐SPI, with no accompanying decrease in elongation at break as a result of strong interaction and with good miscibility among components. As the HL content increased, the HL molecules could self‐aggregate as oblate supramolecular domains, while the stronger interactions between HL and glycerol resulted in the detaching of glycerol from the SPI matrix. It can be concluded that the insertion of HL as single molecules into the SPI matrix would provide materials with optimum mechanical properties. Compared with other lignin/SPI composites, the stretching chains on HL play a key role in the improvement of mechanical properties because of a stronger adhesion of HL onto the SPI matrix as well as the interpenetration of SPI into supramolecular HL domains.

Schematic illustration of the supramolecular domain created by the aggregation of hydroxypropyl lignin, which can interpenetrate with soy protein isolate.

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Schematic illustration of the supramolecular domain created by the aggregation of hydroxypropyl lignin, which can interpenetrate with soy protein isolate.
Monitoring the mycotoxins in food and their biomarkers in the Czech Republic
Authors: Malir Frantisek , Ostry Vladimír , Grosse Yann , Roubal Tomas , Skarkova Jarmila , Ruprich Jiri
Published: May 2006

Testing of the presence of toxigenic microfungi and mycotoxins in foodstuffs in the food chain is an important part of the food safety strategy in The Czech Republic. At the national level, control of their presence in the entire food chain is assured by Public Health Protection Agencies, by the Veterinary Administration and by the Czech Agriculture and Food Inspection Authority. This article summarizes surveillance activities of Public Health Protection Agencies and mycotoxins findings in dietary raw materials and foodstuffs from the 1990s to 2004 in the Czech Republic. At present, the health risk from the mycotoxins exposure from foodstuffs is assessed to be relatively low in the Czech Republic, especially as far as the foodstuffs of the Czech origin are concerned. It may result in late toxic effects (e. g., carcinogenic risk) following a single or repeated ingestion of low mycotoxins doses from foodstuffs. Nevertheless, the overall situation may change due to the globalization of the food market. In order to minimize the risk associated with mycotoxins and eliminate their impact on Czech public health, continuous monitoring of the presence of toxigenic moulds, mycotoxins, and their biomarkers is necessary, in conjunction with strict respect to European Union legislation.
Contamination of free‐range chicken eggs with dioxins and dioxin‐like polychlorinated biphenyls
Authors: Schoeters Greet , Hoogenboom Ron
Published: May 2006

Dioxins and dioxin‐like (DL) polychlorinated biphenyls (PCB) are persistent organic pollutants that enter the body mainly by food intake. A small margin exists between current exposure levels in the human population and the levels causing biological effects. Therefore, stringent control of concentrations of these contaminants in food and feed is needed. Eggs from free‐range chicken are increasingly becoming an important part of the diet. These eggs have a higher risk of being contaminated with increased levels of dioxins and DL‐PCB than barn or cage eggs. Ingestion of soil particles from environmentally contaminated areas may contribute to elevated dioxin levels in free‐range chicken eggs. Available data show that current soil levels of dioxins and DL‐PCB in residential and agricultural areas in Europe often appear to be too high to produce free‐range eggs with dioxin levels below the current limit values in the EU. On the other hand, polychlorinated dibenzo‐p‐dioxins/polychlorinated dibenzofurans concentrations in eggs from free‐range chicken are not necessarily above the limit values. Contamination levels in soil should be kept low and should be controlled in areas with free foraging chicken although all modifying factors that influence uptake of dioxins and PCB from the environment and transfer into eggs are yet not well understood.
A note on the power of Fisher's least significant difference procedure
Authors: Meier Ulrich
Published: May 2006

Fisher's least significant difference (LSD) procedure is a two‐step testing procedure for pairwise comparisons of several treatment groups. In the first step of the procedure, a global test is performed for the null hypothesis that the expected means of all treatment groups under study are equal. If this global null hypothesis can be rejected at the pre‐specified level of significance, then in the second step of the procedure, one is permitted in principle to perform all pairwise comparisons at the same level of significance (although in practice, not all of them may be of primary interest). Fisher's LSD procedure is known to preserve the experimentwise type I error rate at the nominal level of significance, if (and only if) the number of treatment groups is three. The procedure may therefore be applied to phase III clinical trials comparing two doses of an active treatment against placebo in the confirmatory sense (while in this case, no confirmatory comparison has to be performed between the two active treatment groups). The power properties of this approach are examined in the present paper. It is shown that the power of the first step global test – and therefore the power of the overall procedure – may be relevantly lower than the power of the pairwise comparison between the more‐favourable active dose group and placebo. Achieving a certain overall power for this comparison with Fisher's LSD procedure – irrespective of the effect size at the less‐favourable dose group – may require slightly larger treatment groups than sizing the study with respect to the simple Bonferroni alpha adjustment. Therefore if Fisher's LSD procedure is used to avoid an alpha adjustment for phase III clinical trials, the potential loss of power due to the first‐step global test should be considered at the planning stage. Copyright © 2006 John Wiley & Sons, Ltd.
Heat Sealing measurement by an innovative technique
Authors: Aithani Dinesh , Lockhart Hugh , Auras Rafael , Tanprasert Krittika
Published: May 2006

To obtain a proper heat seal is an important requirement in packaging, since seal failure is a more frequent cause of product deterioration than the package itself. Different kinds of seal, such as peelable or non‐peelable, can be obtained by changing the conditions under which a material is sealed. Therefore, identifying these conditions is very important. A new technique, the method for measuring temperature of melting surface (MTMS), was used to predict the strongest peelable seal on various packaging commercial films. The temperature of the seal interface was measured using a thermocouple. The time–temperature profile, which was obtained by means of a thermocouple, was electronically processed so as to obtain the derivatives of the profile. The inflection point, also called the fusion point, was located on these profiles. This inflection point is associated with the physical change of the state of the material being sealed. The inflection point analysis was done using two different methods: (a) the MTMS method, based on the second derivative of temperature data with time; (b) ‘Table Curve’ software, based on non‐linear regression. This technique was successfully used to evaluate widely used packaging films such as LDPE, HDPE, LLDPE and CPP. The inflection point for these films was identified and the seal strength was verified using a universal testing machine. This method appears to be applicable to design the strongest peelable heat seals for many packaging materials. It also seems to have promise as a method of process measurement and validation for heat seal processes. Copyright © 2006 John Wiley & Sons, Ltd.
Transgenically expressed viral RNA silencing suppressors interfere with microRNA methylation in Arabidopsis
Authors: Yu Bin , Chapman Elisabeth J. , Yang Zhiyong , Carrington James C. , Chen Xuemei
Published: May 2006

HEN1‐dependent methylation of the 3′‐terminal nucleotide is a crucial step in plant microRNA (miRNA) biogenesis. Here we report that several viral RNA silencing suppressors (P1/HC‐Pro, p21 and p19) inhibit miRNA methylation. These suppressors have distinct effects on different miRNAs. We also show that miRNA∗ is methylated in vivo in a suppressor‐sensitive manner, suggesting that the viral proteins interfere with miRNA/miRNA∗ duplexes. p19 and p21 bind both methylated and unmethylated miRNA/miRNA∗ duplexes in vivo. These findings suggest miRNA/miRNA∗ as the in vivo substrates for the HEN1 miRNA methyltransferase and raise intriguing possibilities regarding the cellular location of miRNA methylation.
PTEN, a negative regulator of PI3 kinase signalling, alters tau phosphorylation in cells by mechanisms independent of GSK‐3
Authors: Kerr Fiona , Rickle Annika , Nayeem Naushaba , Brandner Sebastian , Cowburn Richard F. , Lovestone Simon
Published: May 2006

Deregulation of PTEN/Akt signalling has been recently implicated in the pathogenesis of Alzheimer's disease (AD), but the effects on the molecular processes underlying AD pathology have not yet been fully described. Here we report that overexpression of PTEN reduces tau phosphorylation in CHO cells. This effect was abrogated by mutant PTEN constructs with either a catalytically inactive point mutation (C124S) or with only inactive lipid phosphatase activity (G129E), suggesting an indirect, lipid phosphatase‐dependent process. The predominant effects of PTEN on tau appeared to be mediated by reducing ERK1/2 activity, but were independent of Akt, GSK‐3, JNK and the tau phosphatases PP1 and PP2A. Our studies provide evidence for an effect of PTEN on the phosphorylation of tau in AD pathogenesis, and provide some insight into the mechanisms through which deregulation of PTEN may contribute towards the progression of tauopathy.
Kinematics of homogeneous axisymmetric tubulence
Authors: Lindborg Erik
Published: May 2006

It is shown that the expressions for the correlation tensors of homogeneous axisymmetric turbulence can be considerably simplifed compared to previous analyses of Batchelor (1946) and Chandrasekhar (1950). Representations of the axisymmetric two-point correlations tensors are found, such that each measurable correlation corresponds to a single scalar function, and moreover such that the equations of continuity relating different tensor components to each other take the most simple form. Reflectional symmetry in planes normal to but not in planes through the axis of symmetry is demanded, which allows a full description of states with rotation about the axis of symmetry. The second and third-order velocity correlation tensors and the first-order pressure velocity correlation tensor are analysed with the new method. Small separation expansions of the correlation functions yield the quantities which have to be measured to determine various terms in the governing equations for the Reynolds stresses and the dissipation tensor. A scalar Poisson equation for the pressure-strain is derived. and the single-pint solution is written as a sum of integrals over measurable correlation functions. The simplified analysis can be of great experimental importance. It reveals in a simple way how a full experimental picture of homogeneous axisymmetric turbulence can be obtained by measuring components of the velocity at two points at variable distance from each other on a line perpendicular to the mean flow in a wind tunnel. By using the Fouricr Besscl transform it is also shown that the three-demensional energy, transfer, and pressure stain spectra can be extracted from such measurements.
Runup of solitary waves on a circular Island
Authors: Liu Philip L. -F. , Cho Yong-Sik , Briggs Michael J. , Kanoglu Utku , Synolakis Costas Emmanuel
Published: May 2006

This is a study of the interactions of solitary waves climbing up a circular island. A series of large-scale laboratory experiments with waves of different incident height-to-depth ratios and different crest lengths is described. Detailed two-dimensional run-up height measurements and time histories of surface elevations around the island are presented. A numerical model based on the two-dimensional shallow-water wave equations including runup calculations was developed. Numerical model predictions agreed very well with the laboratory data and the model was used to study wave trapping and the effect of slope. Under certain conditions, enhanced runup and wave trapping on the lee side of the island were observed, suggesting a possible explanation for the devastation reported by field surveys in Babi Island off Flores, Indonesia, and in Okushiri Island, Japan.
Clinical Diagnosis and SCID-II Assessment of DSM-III-R Personality Disorders
Authors: Fridell Mats , Hesse Morton
Published: May 2006

Aim: To assess the diagnostic concordance of SCID-II and clinicians' estimation of DSM-III-R personality disorders of substance abusers. Method: Clinical diagnoses of substance abusers in inpatient treatment were compared with SCID-II diagnoses (N = 138). Findings: The overall prevalence of personality disorder was 79% for clinical diagnosis and 80% for SCID-II diagnosis. Substantial agreement was found for borderline personality disorder, and moderate agreement was found for presence of any personality disorder, and antisocial personality disorder. All other disorders had slight to fair agreement. Antisocial personality disorder was overdiagnosed by clinical diagnosis but schizotypal, obsessive-compulsive, passive-aggressive, and masochistic personality disorders were reported more often by SCID-II. Selecting only the primary clinical diagnosis and omitting additional clinical diagnoses, reduced agreement with SCID-II diagnoses. Implications: Clinical diagnosis and structured interviews are not interchangeable, and produce somewhat different profiles of diagnoses for a group of substance abusers, but the two methods for diagnosing personality disorders converge for the two most common personality disorders in substance abusers. Rare and less-known diagnoses tend to be underreported whereas common and well-known disorders tend to be slightly overdiagnosed by clinical diagnosis as compared with a semistructured interview, especially if only one clinical diagnosis is noted.
Confirmatory Factor Analysis and Psychometric Properties of the Anxiety Sensitivity Index - Revised in Clinical and Normative Populations
Authors: Armstrong Kerry A. , Khawaja Nigar G. , Oei Tian P.S.
Published: May 2006

The present investigation aimed to critically examine the factor structure and psychometric properties of the Anxiety Sensitivity Index - Revised (ASI-R). Confirmatory factor analysis using a clinical sample of adults (N = 248) revealed that the ASI-R could be improved substantially through the removal of 15 problematic items in order to account for the most robust dimensions of anxiety sensitivity. This modified scale was renamed the 21-item Anxiety Sensitivity Index (21-item ASI) and reanalyzed with a large sample of normative adults (N = 435), revealing configural and metric invariance across groups. Further comparisons with other alternative models, using multi-sample analysis, indicated the 21-item ASI to be the best fitting model for both groups. There was also evidence of internal consistency, test-retest reliability, and construct validity for both samples suggesting that the 21-item ASI is a useful assessment device for investigating the construct of anxiety sensitivity in both clinical and normative populations.
The Cross-Cultural Equivalence of Parental Rearing Measure: EMBU-C
Authors: Deković Maja , ten Have Margreet , Vollebergh Wilma A.M. , Pels Trees , Oosterwegel Annerieke , Wissink Inge B. , De Winter Andrea F. , Verhulst Frank C. , Ormel Johan
Published: May 2006

We examined the cross-cultural equivalence of a widely used instrument that assesses perceived parental rearing, the EMBU-C, among native Dutch and immigrant adolescents living in The Netherlands. The results of a multigroup confirmatory factor analysis indicated that the factor structure of the EMBU-C, consisting of three latent factors (Warmth, Rejection, and Overprotection), and reliabilities of these scales are similar in both samples. These findings lend further support for the factorial and construct validity of this instrument. The comparison of perceived child rearing between native Dutch and immigrant adolescents showed cultural differences in only one of the assessed dimensions: Immigrant adolescents perceive their parents as more overprotective than do Dutch adolescents.
Measurements of rovibronic line oscillator strengths of N2 in the 83.4 nm region: A high‐resolution high‐temperature study
Authors: Wu C. Y. Robert , Judge D. L. , Matsui T.
Published: May 2006

We report the rovibronic line oscillator strengths of N2 in the 83.4 nm region at high temperatures measured by using ultrahigh‐resolution photoabsorption spectroscopy. The measurements have been carried out using a resolution of 6.5 × 10−4 nm and at temperatures of 600, 535, and 295 K. The N2 absorption features in the 83.4 nm region mainly involve the (0,0) band of the c′6‐X transition and the weaker (2,0) band of the c4‐X and the (25,0) band of the b′–X transitions. Spectral perturbation effects in the c′6‐X transition have been observed at J (rotational quantum number) >14. The presence of weak transitions and hot band transitions further contribute to the spectral complexity, especially in the long wavelength side. By integrating over each individual absorption profile for each rotational line up to J = 16, the rovibronic line oscillator strengths of the (0,0) c′6‐X transition of N2 are measured. For the spectral regions with strong perturbations and overlapping by the weak (2,0) c4‐X and the (25,0) b′–X transitions, we have measured the effective oscillator strength values with a roughly equal spectral step covering the perturbed features in the 83.422–83.477 nm region. The present results will contribute to a correct interpretation of the OII 83.4 nm EUV airglow emission of the Earth by elucidating the effect of temperature on the atmospheric extinction due to absorption by N2 and O2.
Links between topography, wind, deflation, lakes and dust: The case of the Bodélé Depression, Chad
Authors: Washington R. , Todd M. C. , Lizcano G. , Tegen I. , Flamant C. , Koren I. , Ginoux P. , Engelstaedter S. , Bristow C. S. , Zender C. S. , Goudie A. S. , Warren A. , Prospero J. M.
Published: May 2006

The Bodélé Depression, Chad is the planet's largest single source of dust. Deflation from the Bodélé could be seen as a simple coincidence of two key prerequisites: strong surface winds and a large source of suitable sediment. But here we hypothesise that long term links between topography, winds, deflation and dust ensure the maintenance of the dust source such that these two apparently coincidental key ingredients are connected by land‐atmosphere processes with topography acting as the overall controlling agent. We use a variety of observational and numerical techniques, including a regional climate model, to show that: 1) contemporary deflation from the Bodélé is delineated by topography and a surface wind stress maximum; 2) the Tibesti and Ennedi mountains play a key role in the generation of the erosive winds in the form of the Bodélé Low Level Jet (LLJ); 3) enhanced deflation from a stronger Bodélé LLJ during drier phases, for example, the Last Glacial Maximum, was probably sufficient to create the shallow lake in which diatoms lived during wetter phases, such as the Holocene pluvial. Winds may therefore have helped to create the depression in which erodible diatom material accumulated. Instead of a simple coincidence of nature, dust from the world's largest source may result from the operation of long term processes on paleo timescales which have led to ideal conditions for dust generation in the world's largest dust source. Similar processes plausibly operate in other dust hotspots in topographic depressions.
Very low frequency earthquakes within accretionary prisms are very low stress‐drop earthquakes
Authors: Ito Yoshihiro , Obara Kazushige
Published: May 2006

We report characteristic P wave spectra and stress drops of very low frequency (VLF) earthquakes that occurred within the accretionary prism along the Nankai Trough, southwestern Japan. Although many VLF earthquakes showed no distinct phases on a raw seismogram, a few showed slightly distinct phases. The arrival times of some phases were consistent with the calculated P wave arrival times. The corner frequencies of the VLF earthquakes were calculated using the stacked P wave spectra assuming an omega‐square spectrum. Stress drops were very low, i.e., in the range of 0.1–10 kPa, which corresponds to 0.1%–1% of those of ordinary earthquakes. Such extremely low stress drops of the VLF earthquakes suggest that the fault strength within the accretionary prism may have weakened due to the existence of a fluid within the thrust fault system of the accretionary prism.
Shock-timing experiments using double-pulse laser irradiation
Authors: Boehly T. R. , Vianello E. , Miller J. E. , Craxton R. S. , Collins T. J. B. , Goncharov V. N. , Igumenshchev I. V. , Meyerhofer D. D. , Hicks D. G. , Celliers P. M. , Collins G. W.
Published: May 2006

The timing of multiple shock waves is crucial to the performance of inertial confinement fusion ignition targets. Presented are measurements of velocities and optical self-emission from shock waves in polystyrene targets driven by two 90-ps pulses separated by 1.5–2ns. These pulses drive two shock waves that coalesce in the target, and the resultant velocity histories, coalescence times, and transit times are unambiguously observed in both velocity interferometry and self-emission data. These results are in good agreement with one-dimensional hydrodynamics code predictions.
Commissioning of the University of Maryland Electron Ring (UMER): Advances toward multiturn operation
Authors: Walter Mark , Bai G. , Bernal S. , Feldman D. , Godlove T. , Haber I. , Holloway M. , Kishek R. , O’Shea P. , Papadopoulos C. , Quinn B. , Reiser M. , Stratakis D. , Tobin C. , Wilson M.
Published: May 2006

The University of Maryland Electron Ring (UMER) is a low-energy, high current recirculator for beam physics research [M. Reiser et al., in Proceedings of the 1999 Particle Accelerator Conference, New York, NY (IEEE, New York, 1999), p. 234]. Ring construction is completed for multiturn operation of beams over a broad range of intensities and initial conditions. UMER is an extremely versatile experimental platform with a beam current of up to 100mA and a pulse length as long as 100ns. UMER is addressing issues in beam physics relevant to many applications that require intense beams of high quality, such as advanced concept accelerators, free electron lasers, spallation neutron sources, and future heavy-ion drivers for inertial fusion. The primary focus of this paper is to present experimental results in the areas of beam steering and multiturn operation of the ring. Unique beam steering algorithms now include measurement of the beam response matrix at each quadrupole and matrix inversion by singular value decomposition. With these advanced steering methods, transport of an intense beam over four turns (144 full lattice periods) of the ring has been achieved.
On spatial and material covariant balance laws in elasticity
Authors: Yavari Arash , Marsden Jerrold E. , Ortiz Michael
Published: May 2006

This paper presents some developments related to the idea of covariance in elasticity. The geometric point of view in continuum mechanics is briefly reviewed. Building on this, regarding the reference configuration and the ambient space as Riemannian manifolds with their own metrics, a Lagrangian field theory of elastic bodies with evolving reference configurations is developed. It is shown that even in this general setting, the Euler-Lagrange equations resulting from horizontal (referential) variations are equivalent to those resulting from vertical (spatial) variations. The classical Green-Naghdi-Rivilin theorem is revisited and a material version of it is discussed. It is shown that energy balance, in general, cannot be invariant under isometries of the reference configuration, which in this case is identified with a subset of R3. Transformation properties of balance of energy under rigid translations and rotations of the reference configuration is obtained. The spatial covariant theory of elasticity is also revisited. The transformation of balance of energy under an arbitrary diffeomorphism of the reference configuration is obtained and it is shown that some nonstandard terms appear in the transformed balance of energy. Then conditions under which energy balance is materially covariant are obtained. It is seen that material covariance of energy balance is equivalent to conservation of mass, isotropy, material Doyle-Ericksen formula and an extra condition that we call configurational inviscidity. In the last part of the paper, the connection between Noether’s theorem and covariance is investigated. It is shown that the Doyle-Ericksen formula can be obtained as a consequence of spatial covariance of Lagrangian density. Similarly, it is shown that the material Doyle-Ericksen formula can be obtained from material covariance of Lagrangian density.
Transport and fluctuations in high temperature spheromak plasmas
Authors: McLean H. S. , Wood R. D. , Cohen B. I. , Hooper E. B. , Hill D. N. , Moller J. M. , Romero-Talamas C. , Woodruff S.
Published: May 2006

Higher electron temperature (Te>350eV) and reduced electron thermal diffusivity (χe<10m2∕s) is achieved in the Sustained Spheromak Physics Experiment (SSPX) by increasing the discharge current=Igun and gun bias flux=ψgun in a prescribed manner. The internal current and q=safety factor profile derived from equilibrium reconstruction as well as the measured magnetic fluctuation amplitude can be controlled by programming the ratio λgun=μ0Igun∕ψgun. Varying λgun above and below the minimum energy eigenvalue=λFC of the flux conserver (∇×B⃗=λFCB⃗) varies the q profile and produces the m∕n=poloidal/toroidal magnetic fluctuation mode spectrum expected from mode-rational surfaces with q=m∕n. The highest Te is measured when the gun is driven with λgun slightly less than λFC, producing low fluctuation amplitudes (<1%) and 1∕2<q<2∕3. Transport analysis shows a reduction in χe as Te increases, differing from Bohm or open field line transport models where χe increases with Te. Detailed resistive magnetohydrodynamic simulations with the NIMROD code support the analysis of energy confinement in terms of the causal link with the q profile, magnetic fluctuations associated with low-order mode-rational surfaces, and the quality of magnetic surfaces.
Hamiltonian theory of constrained impulsive motion
Authors: Cortés Jorge , Vinogradov Alexandre M.
Published: May 2006

This paper considers systems subject to nonholonomic constraints which are not uniform on the whole configuration manifold. When the constraints change, the system undergoes a transition in order to comply with the new imposed conditions. Building on previous work on the Hamiltonian theory of impact, we tackle the problem of mathematically describing the classes of transitions that can occur. We propose a comprehensive formulation of the transition principle that encompasses the various impulsive regimes of Hamiltonian systems. Our formulation is based on the partial symplectic formalism, which provides a suitable framework for the dynamics of nonholonomic systems. We pay special attention to mechanical systems and illustrate the results with several examples.
Method for measuring radial impurity emission profiles using correlations of line integrated signals
Authors: Kuldkepp M. , Brunsell P. R. , Drake J. , Menmuir S. , Rachlew E.
Published: May 2006

A method of determining radial impurity emission profiles is outlined. The method uses correlations between line integrated signals and is based on the assumption of cylindrically symmetric fluctuations. Measurements at the reversed field pinch EXTRAP T2R show that emission from impurities expected to be close to the edge is clearly different in raw as well as analyzed data to impurities expected to be more central. Best fitting of experimental data to simulated correlation coefficients yields emission profiles that are remarkably close to emission profiles determined using more conventional techniques. The radial extension of the fluctuations is small enough for the method to be used and bandpass filtered signals indicate that fluctuations below 10kHz are cylindrically symmetric. The novel method is not sensitive to vessel window attenuation or wall reflections and can therefore complement the standard methods in the impurity emission reconstruction procedure.
Lower hybrid turbulence driven by parallel currents and associated electron energization
Authors: McMillan Ben F. , Cairns Iver H.
Published: May 2006

Parallel currents are usually in the form of field-aligned electron drifts in collisionless plasmas. The field-aligned drifts often drive instabilities. For instance, Drake et al. [Science, 299, 873 (2003)] found growth of parallel propagating turbulence initially and strong levels of oblique lower hybrid (LH) waves at later times; substantial parallel electron acceleration was also found. We use collisionless linear theory and quasilinear simulations to study wave growth and parallel electron dynamics in similar systems. In low-β plasmas with intense parallel currents and both with or without parallel E fields, LH waves are shown to grow even for electron distributions stable to the parallel Buneman instability and to accelerate electrons parallel to B very rapidly. This instability may be seen as the oblique limit of the ion acoustic and Buneman instabilities. The quasilinear diffusion via LH waves may release almost all of the available drift energy, and produce stronger electron acceleration and heating than the parallel Buneman instability alone.
Detailed evaluation of the performance of microfluidic T mixers using fluorescence and ultraviolet resonance Raman spectroscopy
Authors: Masca Sergiu I. , Rodriguez-Mendieta Iñigo R. , Friel Claire T. , Radford Sheena E. , Smith D. Alastair
Published: May 2006

A reliable device that produces efficient mixing with a short dead time has enormous utility in the kinetic analysis of biochemical and chemical processes. We have designed two different T mixers that use moderate flow rates (0.2–0.4ml∕s), can monitor reactions up to several milliseconds, and achieve mixing times as low as 20μs. The two mixers are easy to build and dismantle, reliable, and can perform hundreds of experiments without blocking. The first mixer comprises a stainless steel block, containing a microchannel, glued to a quartz cuvette, containing a 200×200μm2 observation channel defining a conventional T mixer. The reactions are monitored by imaging the length of the observation channel onto a charge-coupled device camera. In the second mixer the entire T (200×200μm2 internal cross section) is contained within a 40-mm-long quartz cuvette. We have adopted a novel approach to controlling the entrance channel bore by inserting a stainless steel wire in order to increase the linear speed of the impinging fluids. Using a dye to visualize the flow profile inside the second T mixer, it was shown that in this T geometry segregation of the reactants is observed in the junction between the inlet channels and the observation channel (T junction) and mixing occurs entirely in the observation channel. We thoroughly tested the two mixers through several kinetic reactions using both fluorescence and ultraviolet resonance Raman spectroscopy measurements. We show that both mixers provide efficient mixing with nominal dead times (using 1:10 v∕v dilution), calculated using the quenching of the fluorescence of N-acetyl-L-tryptophanamide by N-bromosuccinimide, of 200±20 and 100±10μs, for each mixer, respectively. However, the ability to monitor within the inlet channels and the entire observation channel of the second mixer shows that this standard approach to estimating the dead time is artifactual, since it relies on assuming a constant flow speed throughout the observation channel, a feature that we show is not adhered to at short distances from the T junction. Using both mixers the refolding of the A state of cytochrome c to the native state was followed by fluorescence and ultraviolet resonance Raman spectroscopy, revealing the ability of these instruments to provide insights into the early stages of protein folding using only milligrams of sample.
Gigahertz operation in flexible transistors on plastic substrates
Authors: Sun Yugang , Menard Etienne , Rogers John A. , Kim Hoon-Sik , Kim Seiyon , Chen Guang , Adesida Ilesanmi , Dettmer Ross , Cortez Rebecca , Tewksbury Alan
Published: May 2006

The combined use of GaAs wires with Ohmic contacts formed from bulk wafers, soft lithographic transfer printing techniques, and optimized device designs enables mechanically flexible transistors to be formed on low-cost plastic substrates, with individual device speeds in the gigahertz range and with high degrees of mechanical bendability. These high-speed devices incorporate materials in simple layouts that can be fabricated with modest lithographic patterning resolution and registration. This letter describes their electrical and mechanical characteristics. The results have the potential to be important to certain large-area, “macroelectronic” systems that can provide for high-speed communication and processing capabilities.
Conversion of spin current into charge current at room temperature: Inverse spin-Hall effect
Authors: Saitoh E. , Ueda M. , Miyajima H. , Tatara G.
Published: May 2006

The inverse process of the spin-Hall effect (ISHE), conversion of a spin current into an electric current, was observed at room temperature. A pure spin current was injected into a Pt thin film using spin pumping, and it was observed to generate electromotive force transverse to the spin current. By changing the spin-current polarization direction, the magnitude of this electromotive force varies critically, consistent with the prediction of ISHE.
Improvement in quantum efficiency of thin film Si solar cells due to the suppression of optical reflectance at transparent conducting oxide/Si interface by TiO2∕ZnO antireflection coating
Authors: Fujibayashi Takashi , Matsui Takuya , Kondo Michio
Published: May 2006

Through experiments and optical simulations the suppression of optical reflection at the transparent conducting oxide/Si interface of thin film Si p-i-n solar cells is shown by application of a TiO2 antireflection (AR) coating. In addition, a deterioration in the transmittance of TiO2 is shown to be due to its reduction by a H2 plasma, which in turn deteriorates the quantum efficiency (QE) at long wavelength. Such a reduction is completely prevented by a ZnO overcoat of ∼10nm. Applying the TiO2∕ZnO AR coating realizes an improvement in QE at all wavelengths with an increase of up to ∼10% at 550nm.