bluuebunny/crossref_metadata_2025 huggingface dataset:
Loss of heterozygosity at 9q32–33 (DBC1 locus) in primary non‐invasive papillary urothelial neoplasm of low malignant potential and low‐grade urothelial carcinoma of the bladder and their associated normal urothelium
Authors: Lopez‐Beltran A , Alvarez‐Kindelan J , Luque RJ , Blanca A , Quintero A , Montironi R , Cheng L , Gonzalez‐Campora R , Requena MJ
Published: March 2008

Tumour recurrence has a major impact on patients with non‐invasive papillary urothelial tumours of the bladder. To explore the role of DBC1 (deleted in bladder cancer 1 locus), a candidate tumour suppressor gene located at 9q32–33, as prognostic marker we have performed loss of heterozygosity (LOH) testing in 49 patients with primary papillary urothelial tumours and associated normal urothelium. Data from the 38 tumours and 11 specimens of normal urothelium that were informative in the LOH study (D9S195 marker) showed that LOH in urothelium (45.4%) but not in non‐invasive tumours (60.5%) was associated with tumour recurrence (p = 0.026) but not to grade or progression. Also, tumours whose normal urothelium had LOH were larger (p = 0.020) and showed cyclin D1 over‐expression (p = 0.032). Non‐significant increased expression of p53, p21Waf1, apoptotic index and tumour proliferation, and decreased expression of p27Kip1 or cyclin D3 also characterized tumours whose normal urothelium had LOH. The expression of these G1–S modulators, apoptotic index and tumour proliferation was more heterogeneous in papillary urothelial tumours, irrespective of having retained heterozygosity or LOH. Also, Bax expression decreased in papillary urothelial tumours having LOH (p = 0.0473), but Bcl‐2 was unrelated to LOH status. In addition, FGFR3 protein expression decreased in LOH tumours (p = 0.036) and in those having LOH in their normal urothelium (p = 0.022). FGFR3 immunohistochemical expression was validated by western blot in selected cases. The survival analysis selected LOH in normal urothelium as a marker of disease‐free survival (log‐rank 5.32, p = 0.021), progression‐free survival (log‐rank 3.97, p = 0.046) and overall survival (log‐rank 4.26, p = 0.038); LOH in tumours was significant in progression‐free survival (log‐rank 3.83, p = 0.042). It is concluded that LOH at the DBC1 locus in normal urothelium seems to be relevant in the prognosis of non‐invasive papillary tumours of the bladder via selecting cases with increased proliferation, frequent alterations of the G1–S phase modulators, and decreased FGFR3 protein expression. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Effect of glass fibers on rheology, thermal and mechanical properties of recycled PET
Authors: Kráčalík Milan , Pospíšil Ladislav , Šlouf Miroslav , Mikešová Jana , Sikora Antonín , Šimoník Josef , Fortelný Ivan
Published: March 2008

PET‐glass fiber composites were prepared by melt mixing of recycled PET with chopped glass fibers (15, 20, and 30 wt%) and their degree of dispersion was assessed by scanning electron microscopy. Rotational rheometry was employed to analyze the interfacial shear strength between the fibers and polymer matrix in the molten state. The composite containing 30 wt% of glass fibers revealed a moderate G′ secondary plateau; hence strong fiber‐matrix interactions were confirmed. Results of mechanical testing were in a good accordance with structural and rheological measurements. The higher rate of mixing under production‐scale conditions resulted in lower fiber‐matrix adhesion and in a similar level of fiber dispersion as compared to the same mixture compounded on pilot‐plant scale. Thermal characterization of the composites was performed by differential scanning calorimetry and total crystalline fraction was analyzed. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers
Polymerization of 2‐pentene with Ni(II) α‐diimine complex/M‐MAO catalyst and structure of the polymer
Authors: Endo Kiyoshi , Kondo Yosiyuki
Published: March 2008

Polymerization of 2‐pentene with [ArNC(An)C(An)·NAr)NiBr2 (Ar2,6‐iPr2C6H3)] (1‐Ni)/M‐MAO catalyst was investigated. A reactivity between trans‐2‐pentene and cis‐2‐pentene on the polymerization was quite different, and trans‐2‐pentene polymerized with 1‐Ni/M‐MAO catalyst to give a high molecular weight polymer. On the other hand, the polymerization of cis‐2‐butene with 1‐Ni/M‐MAO catalyst did not give any polymeric products. In the polymerization of mixture of trans‐ and cis‐2‐pentene with 1‐Ni/M‐MAO catalyst, the Mn of the polymer increased with an increase of the polymer yields. However, the relationship between polymer yield and the Mn of the polymer did not give a strict straight line, and the Mw/Mn also increased with increasing polymer yield. This suggests that side reactions were induced during the polymerization. The structures of the polymer obtained from the polymerization of 2‐ pentene with 1‐Ni/M‐MAO catalyst consists of CH2CH2CH(CH2CH3), CH2 CH2CH2CH(CH3), CH2CH(CH2CH2CH3), and methylene sequence (CH2)n (n ≥ 5) units, which is related to the chain walking mechanism. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2858–2863, 2008
Global Rainbow Refractometry with a Selective Imaging Method
Authors: Wilms Jochen , Gréhan Gérard , Lavergne Gérard
Published: March 2008

Originally developed to measure the refractive index, global rainbow refractometry also permits the extraction of a size distribution. When this technique is applied to a spray with a large number of non‐spherical particles, the number of small particles tends to be overestimated. A new approach in data acquisition is presented to solve this problem at least partially, resulting in a global rainbow of mainly spherical particles. Thus, measurement errors due to non‐sphericity can be minimized. The global rainbow is constructed from an image series of rainbows of individual droplets, where images of the most spherical droplets are selected by use of certain criteria derived from computations of rainbows of single spheres using the Lorenz‐Mie theory.

The method is tested with measurements in a spray. The mean droplet temperature and the size distribution, obtained from the inversion of the global rainbow, are compared to results obtained without using the selective imaging method and to results from other measurement techniques. The comparison of the results shows a better agreement when the selective imaging method is applied, especially for size distribution measurements close to the atomizer where a high amount of non‐spherical droplets can be expected.
Dark proteins: Effect of inclusion body formation on quantification of protein expression
Authors: Iafolla Marco A. J. , Mazumder Mostafizur , Sardana Vandit , Velauthapillai Tharsan , Pannu Karanbir , McMillen David R.
Published: March 2008

Plasmid‐borne gene expression systems have found wide application in the emerging fields of systems biology and synthetic biology, where plasmids are used to implement simple network architectures, either to test systems biology hypotheses about issues such as gene expression noise or as a means of exerting artificial control over a cell's dynamics. In both these cases, fluorescent proteins are commonly applied as a means of monitoring the expression of genes in the living cell, and efforts have been made to quantify protein expression levels through fluorescence intensity calibration and by monitoring the partitioning of proteins among the two daughter cells after division; such quantification is important in formulating the predictive models desired in systems and synthetic biology research. A potential pitfall of using plasmid‐based gene expression systems is that the high protein levels associated with expression from plasmids can lead to the formation of inclusion bodies, insoluble aggregates of misfolded, nonfunctional proteins that will not generate fluorescence output; proteins caught in these inclusion bodies are thus “dark” to fluorescence‐based detection methods. If significant numbers of proteins are incorporated into inclusion bodies rather than becoming biologically active, quantitative results obtained by fluorescent measurements will be skewed; we investigate this phenomenon here. We have created two plasmid constructs with differing average copy numbers, both incorporating an unregulated promoter (PLtetO‐1in the absence of TetR) expressing the GFP derivative enhanced green fluorescent protein (EGFP), and inserted them intoEscherichia colibacterial cells (a common model organism for work on the dynamics of prokaryotic gene expression). We extracted the inclusion bodies, denatured them, and refolded them to render them active, obtaining a measurement of the average number of EGFP per cell locked into these aggregates; at the same time, we used calibrated fluorescent intensity measurements to determine the average number of active EGFP present per cell. Both measurements were carried out as a function of cellular doubling time, over a range of 45–75 min. We found that the ratio of inclusion body EGFP to active EGFP varied strongly as a function of the cellular growth rate, and that the number of “dark” proteins in the aggregates could in fact be substantial, reaching ratios as high as approximately five proteins locked into inclusion bodies for every active protein (at the fastest growth rate), and dropping to ratios well below 1 (for the slowest growth rate). Our results suggest that efforts to compare computational models to protein numbers derived from fluorescence measurements should take inclusion body loss into account, especially when working with rapidly growing cells. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Humidity‐sensitive characteristic of Ba0.99La0.01SnO3
Authors: Upadhyay Shail
Published: March 2008

Samples of Ba0.99La0.01SnO3 (abbreviated name BSL01) have been synthesized by a solid‐state ceramic route at 1200 °C for 4 h. Synthesized powders have been characterized using techniques such as X‐ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X‐ray analysis (EDXA). From XRD data, single‐phase solid‐solution formation has been confirmed. SEM of the sample exhibited a porous nature with small grain size in the range 0.2–0.4 μm. EDXA showed that the surface of the sample is barium deficient and oxygen rich. The distribution in pore size, average pore diameter and% porosity were obtained from the mercury‐intrusion method. The average pore diameter and% porosity are 0.34 μm and 26, respectively. At room temperature the effect of humidity on conductance and capacitance in the frequency range 20 Hz – 1 MHz and relative humidity (RH) range 10–95% have been measured. It is observed that frequency has more influence on capacitance as compared to resistance. The variation of conductivity with RH is linear whereas of the capacitance is nonlinear. The response and recovery times are 44 s and 56 s, respectively. The hygroscopic nature of the sample has been supported by Fourier transforms infrared (FTIR) and thermogravimetric analysis (TGA) data. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application of measurements of internal friction amplitude dependences for tests of ceramic materials
Authors: Bruś Beata , Zachariasz Radosław , Zarycka Aldona , Czerwiec Marek , Ilczuk Jan
Published: March 2008

An aim of this work was to show possibilities of the application of internal friction (IF) measurements in investigations of processes taking place in ceramic materials responsible for dissipation of energy and an application of IF for an interpretation of maxima observed for the temperature dependences of the IF. For the measurements, ceramic specimens of a PZT type were used. Three peaks of IF, relaxation PR1, PR2 and phase transition PF, were observed for the IF temperature dependences obtained. In order to determine the mechanisms responsible for relaxation and phase transition peak formation, measurements of amplitude of internal friction (AIF) relationships were performed. An explanation of the Q–1 = f (εam) AIF dependences was made on the basis of the Granato–Lücke model. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ferrimagnetism and antiferro‐ magnetism in half‐metallic Heusler alloys
Authors: Galanakis Iosif , Özdoğan Kemal , Şaşıoğlu Ersoy , Aktaş Bekir
Published: March 2008

Half‐metallic Heusler alloys are among the most promising materials for future applications in spintronic devices. Although most Heusler alloys are ferromagnets, ferrimagnetic or antiferromagnetic (also called fully‐compensated ferrimagnetic) alloys would be more desirable for applications due to the lower stray fields. Ferrimagnetism can be either found in perfect Heusler compounds or achieved through the creation of defects in ferromagnetic Heusler alloys. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lattice absorption of Be‐containing semiconductor alloys determined by spectroscopic ellipsometry
Authors: Wronkowska A. A. , Skowroński Ł. , Wronkowski A. , Zieliński Ł. , Firszt F. , Marasek A. , Paszkowicz W. , Arwin H.
Published: March 2008

Lattice absorption of Zn1–x –y Bex Mgy Se and Cd1–x –y Bex Zny Se mixed crystals grown by a high pressure Bridgman method has been investigated by infrared spectroscopic ellipsometry in the wave number range from 230 cm–1 to 5000 cm–1. Ellipsometric spectra of Cd1–x –y Bex Zny Se crystals display features in the spectral range 350–550 cm–1 associated with BeSe‐type phonon modes. In the optical spectra of Zn1–x –y Bex Mgy Se crystals both BeSe‐type and MgSe‐type lattice absorption bands are detected. The MgSe‐like modes are located at approximately 300 cm–1. The frequencies and oscillator strengths of optical phonon modes depend strongly on the alloy composition. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stress and stress monitoring in SiC–Si heterostructures
Authors: Pezoldt Jörg , Nader Richard , Niebelschütz Florentina , Cimalla Volker , Stauden Thomas , Zgheib Charbel , Masri Pierre
Published: March 2008

Infrared ellipsometry is a valuable tool to investigate the average stress and the stress distribution in thin silicon carbide layers grown on silicon as well as to monitor the changes in the stress state during device processing. It was obtained that low temperature carbonization in combination with low temperature epitaxial growth led to a compressive stress component in the SiC–Si interface region, whereas the average stress state is tensile. Ge incorporation in the interface lowered the tensile residual stress component. Metallization of SiC increases the tensile stress in the SiC on Si. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monitoring critical dimensions of bidimensional gratings by spectroscopic ellipsometry and Mueller polarimetry
Authors: Foldyna M. , De Martino A. , Garcia‐Caurel E. , Ossikovski R. , Bertin F. , Hazart J. , Postava K. , Drevillon B.
Published: March 2008

In this work we characterized two bidimensional gratings consisting each of a square array of square holes etched in a photoresist layer deposited on silicon. Data were taken on both samples with a spectroscopic UV–VIS ellipsometer (SE) operated at 70° incidence and zero azimuth (with the incidence plane parallel to the lines of holes) and a VIS Mueller matrix polarimeter (MMP) at various incidence and azimuthal angles. The robustness of the parameters derived from the MMP data was evaluated from the stability of the values provided by regression the spectra taken at different angles. The optimal measurement geometries, featuring high sensitivity and low correlation of the fitting parameters, were determined theoretically, and validated experimentally with the sample featuring wider holes (500 × 500 nm), for which 45° incidence provided better results than the usual 70° value. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of biosensor based on imaging ellipsometry
Authors: Jin G.
Published: March 2008

The concept of biosensor based on imaging ellipsometry was proposed ten years ago. Its principle and the methodology as well as some solutions to problems which have to be faced during the development are mentioned. Its properties of phase sensitive, high throughput and fast sampling, as well as label‐free, sensitivity better than 1 ng/ml for Immunoglobulin G, and real‐time analysis for protein interaction process, etc. provide a potential for applications in biomedicine field. The recent biosensing development with total internal reflection imaging ellipsometry is presented also. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
In vitro inhibition of Helicobacter pylori growth and adherence to gastric mucosal cells by Pycnogenol®
Authors: Rohdewald Peter , Beil Winfried
Published: March 2008

The emergence of antibiotic resistant H. pylori strains has necessitated the identification of alternative additive therapies for the treatment of this infection. The study tested whether a specific pine bark extract (Pycnogenol®) is effective in inhibiting the growth and adherence of H. pylori in vitro.

Inhibition of H. pylori growth by Pycnogenol® was tested in liquid medium as well as in an in vitro model by using sessile bacteria attached to AGS cells. Adherence was determined by co‐incubation of gastric cells with Pycnogenol® and H. pylori in vitro.

Pycnogenol® inhibited H. pylori growth in suspension with an MIC50 of 12.5 µg/mL. Growth of H. pylori in infected cells was reduced to 10% of the control value by 125 µg/mL Pycnogenol®. Adherence of H. pylori to gastric cells was reduced by 70% after 3 h incubation with 125 µg/mL Pycnogenol®.

The results show a significant, yet limited inhibition of growth and adherence of H. pylori to gastric cells by Pycnogenol®. In vivo studies have to demonstrate the clinical relevance of these findings. Copyright © 2008 John Wiley & Sons, Ltd.
A new rapid micro‐method for the molecular‐chemical characterization of rhizodeposits by field‐ionization mass spectrometry
Authors: Leinweber Peter , Eckhardt Kai‐Uwe , Fischer Holger , Kuzyakov Yakov
Published: March 2008

Time‐consuming investigation of rhizodeposit composition by leaching, freeze‐drying of leachate, and pyrolysis‐field ionization mass spectrometry (Py‐FIMS) of solid samples was replaced by direct Py‐FIMS of a 5 µL liquid rhizodeposit sample which was evaporated overnight in the quartz tube of a mass spectrometer inlet system. Application of this new rapid technique to a set of 14 liquid rhizodeposit samples from maize (Zea mays L.), leached twice with a time lag of 80 min, unequivocally showed the effect of soil texture on the chemical composition of the rhizodeposits. Irrespective of leaching time, a partial least‐squares analysis separated the Py‐FI mass spectra of the maize rhizodeposits leached from a soil from those leached from a soil + quartz sand‐mixture (prepared by addition of 50% w/w quartz sand to the original soil). The signals which had the strongest discrimination power and were significantly enriched in leachates from the soil + quartz sand were assigned to sugars, peptides and polyamines. Mass signals of putrescine and cadaverine, a priori not expected in the rhizodeposits, were indicators of modified root environment and rhizosphere processes in the soil + quartz sand. In conclusion, the new rapid mass spectrometric profiling method is suitable for rhizosphere research because it requires very small sample volumes, is fast and highly sensitive to detect and quantify a wide range of a priori expected and unexpected organic substances. Copyright © 2008 John Wiley & Sons, Ltd.
PeakSelect: preprocessing tandem mass spectra for better peptide identification
Authors: Zhang Jingfen , He Simin , Ling Charles X. , Cao Xingjun , Zeng Rong , Gao Wen
Published: March 2008

We present a new preprocessing method, PeakSelect, to improve the accuracy and efficiency of Tandem Mass‐Spec peptide (protein) identification. The fundamental difference between noise and fragment ions in spectra is that ions have isotopes but noise does not. We propose a new and important concept of an Isotope Pattern Vector (IPV) which characterizes the isotope cluster of fragment ions. Then the noise and real peaks can be distinguished by the quantitative IPV values. PeakSelect first uses a new method of the Gaussian Mixture Model and Expectation‐Maximization (EM) algorithm to find the base intensity level (baseline) in a spectrum. Then PeakSelect selects features based on the IPV and baseline, and constructs a decision tree to automatically classify the peaks into different categories such as noise, single ion peaks, and overlapping peaks. Experiments show that PeakSelect can help to reduce the Mascot searching time and increase the reliability of peptide identifications. In particular, PeakSelect performs well on complex spectra with a large number of peaks from large peptides, and supports more sequence identification than other well‐known systems. Copyright © 2008 John Wiley & Sons, Ltd.
An entrepreneurial perspective on the firm‐environment relationship
Authors: Smith Ken G. , Cao Qing
Published: March 2008

In the organizational theory literature, two perspectives to explain the firm‐environment relationship—the ecology view and the adaptation view—are dominant. We review these perspectives and present a third, less recognized perspective—the entrepreneurial view. The entrepreneurial view recognizes the potential for top managers and firms to, on occasion, proactively shape and influence their environment. Purposeful individual top managers with their variable belief systems take primacy in the entrepreneurial model as they are motivated to engage in aspirational search and take entrepreneurial actions. Entrepreneurial actions potentially disrupt the existing belief systems of market participants by disseminating new information that causes dissonance. This dissonance and debate as part of the market process can lead to a revision in the belief systems of market participants. We show that although the multilevel entrepreneurial perspective is distinct from the ecology and adaptation perspectives, they are, in fact, complementary. Copyright © 2008 Strategic Management Society.
Entrepreneurship and economic growth
Authors: Baumol William J. , Strom Robert J.
Published: March 2008

Entrepreneurs who focus on innovation in their products, their production techniques, and their markets play a key role in economic growth. The direction of their activity is guided by their goals: wealth, power, and prestige. Current institutions, shaped by history and government are critical in determining where entrepreneurs will find it most promising to direct their efforts, sometimes, but not always, benefiting the general welfare. One goal of good policy, therefore, is redesign of institutions so as to attract entrepreneurial activity to beneficial directions. Copyright © 2008 Strategic Management Society.
Networks and strategic entrepreneurship: comments on Comparing alliance network structure across industries: observations and explanations and Strategic networks and entrepreneurial ventures
Authors: Schulze William
Published: March 2008

While a growing body of research supports the notion that interorganizational networks play an important role in shaping the competitive context and influencing a variety of outcomes for growing and established firms alike, concerns about the boundaries and limitations of the theory are rising. This commentary addresses the contributions of the aforementioned articles while underscoring the various theoretical challenges that await those seeking to apply network theory to the nascent field of strategic entrepreneurship. Copyright © 2008 Strategic Management Society.
Entrepreneurship and macroeconomic performance
Authors: Casson Mark , Wadeson Nigel
Published: March 2008

This paper develops a formal model of the impact of entrepreneurship on macroeconomic performance. It examines the role of entrepreneurs in creating markets for novel products. Entrepreneurs take over the coordination role that in traditional neoclassical economic models is performed by the Walrasian auctioneer. Entrepreneurs specialize in collecting information that permits them to make judgmental decisions about innovation. The quality of their judgment determines the success of innovations, and thereby impacts the long‐run performance of the economy. The model demonstrates rigorously that constraints on the supply of entrepreneurship reduce economic performance, and serves to identify the policy instruments that can improve performance by alleviating these constraints. Copyright © 2008 Strategic Management Society.
Use of Quality Management Methods in the Transition from Efficacious Prevention Programs to Effective Prevention Services
Authors: Daniels Vicki-Smith , Sandler Irwin
Published: March 2008

This paper applies concepts and methods developed in management to translate efficacious prevention programs into effective prevention services. The paper describes Quality Function Deployment (QFD) as a method for structured planning and development that connects the needs and wants of the consumer with the design of the product or service. The paper describes basic tools used in quality management, and discusses how they might be applied to prepare a prevention program for implementation by community agencies. Prevention programs are conceptualized as having multiple consumers (i.e., stakeholders), including the participants who receive the service, the service providers, the organizations that deliver the program, and the researchers who evaluate the programs. As an illustration of one step in the application of QFD to translate efficacious prevention programs into effective prevention services, analysis of the needs and preferences of Family Courts for the implementation of an the New Beginnings Program is presented.
The impact of employee satisfaction on quality and profitability in high‐contact service industries
Authors: Yee Rachel W.Y. , Yeung Andy C.L. , Cheng T.C. Edwin
Published: March 2008

The extant operations management literature has extensively investigated the associations among quality, customer satisfaction, and firm profitability. However, the influence of employee attributes on these performance dimensions has rarely been examined. In this study we investigate the impact of employee satisfaction on operational performance in high‐contact service industries. Based on an empirical study of 206 service shops in Hong Kong, we examined the hypothesized relationships among employee satisfaction, service quality, customer satisfaction, and firm profitability. Using structural equations modeling, we found that employee satisfaction is significantly related to service quality and to customer satisfaction, while the latter in turn influences firm profitability. We also found that firm profitability has a moderate non‐recursive effect on employee satisfaction, leading to a “satisfaction–quality–profit cycle”. Our empirical investigation suggests that employee satisfaction is an important consideration for operations managers to boost service quality and customer satisfaction. We provide empirical evidence that employee satisfaction plays a significant role in enhancing the operational performance of organizations in the high‐contact service sector.
Food-chain selenium and human health: spotlight on speciation
Authors: Rayman Margaret P. , Infante Heidi Goenaga , Sargent Mike
Published: March 2008

There is a growing appreciation that it is not just the total intake of dietary Se that is important to health but that the species of Se ingested may also be important. The present review attempts to catalogue what is known about Se species in foods and supplements and the health effects in which they are implicated. The biosynthetic pathways involved in Se assimilation by plants and the way in which Se species are metabolised in animals are presented in order to give an insight into the species likely to be present in plant and animal foods. Known data on the species of Se in the food chain and in food supplements are tabulated along with their concentrations and the analytical methodology used. The latter is important, since identification that is only based on retention-time matching with authentic standards must be considered as tentative: for evidence of structural confirmation, fragmentation of the molecular ion in addition to MS data is required. Bioavailability, as normally defined, is higher for organic Se species. Health effects, both beneficial and toxic, thought to be associated with specific Se species are described. Potent anti-tumour effects have been attributed to the low-molecular-weight species,Se-methyl-selenocysteine and its γ-glutamyl-derivative, found in a number of edible plants of theAlliumandBrassicafamilies. There remain considerable gaps in our knowledge of the forms of Se that naturally occur in foods. Without adequate knowledge of Se speciation, false conclusions may be drawn when assessing Se requirements for optimal health.
Food-chain selenium and human health: emphasis on intake
Authors: Rayman Margaret P.
Published: March 2008

Following the publication of the landmark trial of Clarket al.in 1996 that appeared to show that Se could reduce the risk of cancer, awareness of the importance of Se to human health has markedly increased. As a result, there is now much more aggressive marketing of Se supplements and functional foods, even in situations where additional consumption of Se is inappropriate. The present review addresses how Se gets into the food chain, the wide variability in Se content of foods and the very different levels of intake between countries and regions. Though it is clear that there are adverse consequences for health of both deficient and excessive intake, health effects at intermediate levels of intake are less certain. Thus it is difficult to define optimal intake which depends on a large number of factors, such as which functions of Se are most relevant to a particular disease state, which species of Se is most prominent in the Se source, which health condition is being considered, the adequacy or otherwise of intake of other nutrients, the presence of additional stressors, and lastly whether the ability to make selenoproteins may be compromised. These complexities need to be understood, particularly by policy makers, in order to make informed judgments. Potential solutions for increasing Se intake, where required, include agronomic biofortification and genetic biofortification or, for individuals, increased intake of naturally Se-rich foods, functional foods or supplements. The difficulties of balancing the risks and benefits in relation to Se intake are highlighted.
Dietary single cell protein reduces fatty liver in obese Zucker rats
Authors: Gudbrandsen Oddrun Anita , Wergedahl Hege , Liaset Bjørn , Espe Marit , Mørk Sverre , Berge Rolf Kristian
Published: March 2008

There is growing evidence that dietary proteins may interfere with lipid metabolism. We therefore examined the effects of feeding obese Zucker rats a single cell protein (SCP) with low ratios of methionine:glycine and lysine:arginine for 6 weeks. SCP feeding reduced the hepatic steatosis and lowered the plasma transaminase levels when compared with casein-fed rats (controls). The fatty acid oxidation was increased in liver mitochondria and peroxisomes, whereas the activities of enzymes involved in lipogenesis and TAG biosynthesis were unaffected. SCP feeding affected the fatty acid composition of liver lipids and plasma, and reduced the mRNA levels of the fatty acid desaturases. The decreased gene expression of stearoyl-CoA desaturase suggested that the fatty acids were directed towards oxidation rather than esterification as TAG. The decreased mRNA levels of VLDL-receptor and lipoprotein lipase in the liver after SCP feeding suggested that the uptake of TAG-rich lipoprotein to the liver was decreased. To conclude, the reduced fatty liver by SCP feeding may be caused by the increased capacity for fatty acid β-oxidation in the liver, combined with changed fatty acid composition and possibly a reduced hepatic clearance of circulating VLDL. An increased awareness of the effect of dietary proteins on lipid metabolism could be of relevance in future dietary treatment of non-alcoholic fatty liver disease.
On the compressible Taylor–Couette problem
Authors: MANELA A. , FRANKEL I.
Published: March 2008

We consider the linear temporal stability of a Couette flow of a Maxwell gas within the gap between a rotating inner cylinder and a concentric stationary outer cylinder both maintained at the same temperature. The neutral curve is obtained for arbitrary Mach (Ma) and arbitrarily small Knudsen (Kn) numbers by use of a ‘slip-flow’ continuum model and is verified via comparison to direct simulation Monte Carlo results. At subsonic rotation speeds we find, for the radial ratios considered here, that the neutral curve nearly coincides with the constant-Reynolds-number curve pertaining to the critical value for the onset of instability in the corresponding incompressible-flow problem. With increasing Mach number, transition is deferred to larger Reynolds numbers. It is remarkable that for a fixed Reynolds number, instability is always eventually suppressed beyond some supersonic rotation speed. To clarify this we examine the variation with increasing (Ma) of the reference Couette flow and analyse the narrow-gap limit of the compressible TC problem. The results of these suggest that, as in the incompressible problem, the onset of instability at supersonic speeds is still essentially determined through the balance of inertial and viscous-dissipative effects. Suppression of instability is brought about by increased rates of dissipation associated with the elevated bulk-fluid temperatures occurring at supersonic speeds. A useful approximation is obtained for the neutral curve throughout the entire range of Mach numbers by an adaptation of the familiar incompressible stability criteria with the critical Reynolds (or Taylor) numbers now based on average fluid properties. The narrow-gap analysis further indicates that the resulting approximate neutral curve obtained in the (Ma,Kn) plane consists of two branches: (i) the subsonic part corresponding to a constant ratio (Ma/Kn) (i.e. a constant critical Reynolds number) and (ii) a supersonic branch which at largeMavalues corresponds to a constant productMa Kn. Finally, our analysis helps to resolve some conflicting views in the literature regarding apparently destabilizing compressibility effects.
Instability of optimal non-axisymmetric base-flow deviations in pipe Poiseuille flow
Authors: BEN-DOV GUY , COHEN JACOB
Published: March 2008

The stability of pipe flow when mildly deviating from the developed Poiseuille profile by a non-axisymmetric azimuthally periodic distortion is examined. The motivation for this is to consider deviations, the origin of which may be attributed to small-amplitude disturbances having sinusoidal periodicity along the azimuthal coordinate, which are known to be the ones most amplified by the transient growth linear mechanism. A mathematical technique for finding the minimum energy density of azimuthally periodic deviations triggering exponential instability is presented. The results show that owing to bifurcations multiple solutions of optimal deviations exist. As the Reynolds number is increased additional bifurcations appear and create more distinct solutions. The different solutions correspond to different radial distributions of the deviations, and at Reynolds numbers of about 2000 they are distributed over less than a half of the pipe radius. It is found that the dependence of the optimal deviation velocity leading to instability on the Reynolds number Re is approximately 20/Re. A comparison to axisymmetric base-flow deviations shows that the minimum energy required for an azimuthally periodic deviation to trigger instability is almost twice that for the axisymmetric flow. However, azimuthally periodic deviations, which are shown to have a streaky pattern, may have a role in the self-sustaining process. They may be formed as a result of a transient growth amplification of initial streamwise rolls and can produce, via self-interactions between the resulting growing waves, patterns of streamwise rolls as well.
Natural convection along a heated vertical plate immersed in a nonlinearly stratified medium: application to liquefied gas storage
Authors: FORESTIER M. , HALDENWANG P.
Published: March 2008

We consider free convection driven by a heated vertical plate immersed in a nonlinearly stratified medium. The plate supplies a uniform horizontal heat flux to a fluid, the bulk of which has a stable stratification, characterized by a non-uniform vertical temperature gradient. This gradient is assumed to have a typical length scale of variation, denoted Z0, while Ψ0 is the order of magnitude of the related heat flux that crosses the medium vertically.

We derive an analytic solution to the Boussinesq equations that extends the classical solution of Prandtl to the case of nonlinearly stratified media. This novel solution is asymptotically valid in the regime RaS ≫ 1, where RaS denotes the Rayleigh number of nonlinear stratification, based on Z0, Ψ0, and the physical properties of the medium.

We then apply the new theory to the natural convection affecting the vapour phase in a liquefied pure gas tank (e.g. the cryogenic storage of hydrogen). It is assumed that the cylindrical storage tank is subject to a constant uniform heat flux on its lateral and top walls. We are interested in the vapour motion above a residual layer of liquid in equilibrium with the vapour. High-precision axisymmetric numerical computations show that the flow remains steady for a large range of parameters, and that a bulk stratification characterized by a quadratic temperature profile is undoubtedly present. The application of the theory permits a comparison of the numerical and analytic results, showing that the theory satisfactorily predicts the primary dynamical and thermal properties of the storage tank.
Nonlinear resonances in a laminar wall jet: ejection of dipolar vortices
Authors: WERNZ STEFAN , FASEL HERMANN F.
Published: March 2008

Nonlinear mechanisms leading to the ejection of dipolar vortices from a laminar wall jet are being investigated using highly accurate Navier–Stokes simulations. With a set of well-defined numerical experiments for a forced Glauert wall jet, the nonlinear resonant interaction between the large-amplitude harmonic disturbance and a small-amplitude wave packet is systematically explored using two-dimensional simulations. Generated by a small-amplitude pulse, the wave packet experiences rapid resonant growth in the subharmonic part of its spectrum resulting in vortex mergings and, ultimately, the ejection of a pair of counter-rotating vortices from the wall jet. This two-dimensional subharmonic instability, if not mitigated by competing three-dimensional instabilities, can lead to the detachment of the entire wall jet from the surface. As shown using three-dimensional direct numerical simulations, vortex ejection still occurs in a forced transitional wall jet if the two-dimensional wave packet can reach a large amplitude level upstream of the region of three-dimensional turbulent breakdown. Movies are available with the online version of the paper.
Two alternatives for solving hyperbolic boundary value problems of geophysical fluid dynamics
Authors: HARLANDER UWE , MAAS LEO R. M.
Published: March 2008

Linear internal waves in inviscid bounded fluids generally give a mathematically ill-posed problem since hyperbolic equations are combined with elliptic boundary conditions. Such problems are difficult to solve. Two new approaches are added to the existing methods: the first solves the two-dimensional spatial wave equation by iteratively adjusting Cauchy data such that boundary conditions are satisfied along a predefined boundary. After specifying the data in this way, solutions can be computed using the d'Alembert formula.

The second new approach can numerically solve a wider class of two dimensional linear hyperbolic boundary value problems by using a ‘boundary collocation’ technique. This method gives solutions in the form of a partial sum of analytic functions that are, from a practical point of view, more easy to handle than solutions obtained from characteristics. Collocation points have to be prescribed along certain segments of the boundary but also in the so-called fundamental intervals, regions along the boundary where Cauchy data can be given arbitrarily without over-or under-determining the problem. Three prototypical hyperbolic boundary value problems are solved with this method: the Poincaré, the Telegraph, and the Tricomi boundary value problem. All solutions show boundary-detached internal shear layers, typical for hyperbolic boundary value problems. For the Tricomi problem it is found that the matrix that has to be inverted to find solutions from the collocation approach is ill-conditioned; thus solutions depend on the distribution of the collocation points and need to be regularized.
A particle image velocimetry investigation on laboratory surf-zone breaking waves over a sloping beach
Authors: KIMMOUN O. , BRANGER H.
Published: March 2008

Particle image velocimetry (PIV) measurements were performed in a wave tank under water waves propagating and breaking on a 1/15 sloping beach. The wave transformation occurred in the surf zone over a large domain covering several wavelengths from incipient breaking to swash zone beyond the shoreline. PIV spatial interrogation windows must be small enough to obtain accurate velocities, and one window covers only a small part of the domain. To overcome this problem and to measure the instantaneous velocity field over the whole surf zone area, we have split the full field into 14 overlapping smaller windows of the same size. Local measurements were synchronized with each other using pulsed TTL triggers and wave gauge data. The full velocity field was then reconstructed at every time step by gathering the 14 PIV fields. We then measured the complete space–time evolution of the velocity field over the whole surf zone. We determined also the ensemble-period-average and phase-average components of the flow with their associated fluctuating parts. We used the PIV images and velocity measurements to estimate the void fraction in each point of the surf zone. Special attention was given to the calculation of the spatial derivatives in order to obtain relevant information on vorticity and on the physical terms that appear in the fluctuating kinetic energy transport equation.
Diffusion of swimming model micro-organisms in a semi-dilute suspension
Authors: ISHIKAWA TAKUJI , PEDLEY T. J.
Published: March 2008

The diffusive behaviour of swimming micro-organisms should be clarified in order to obtain a better continuum model for cell suspensions. In this paper, a swimming micro-organism is modelled as a squirming sphere with prescribed tangential surface velocity, in which the centre of mass of the sphere may be displaced from the geometric centre (bottom-heaviness). Effects of inertia and Brownian motion are neglected, because real micro-organisms swim at very low Reynolds numbers but are too large for Brownian effects to be important. The three-dimensional movement of 64 or 27 identical squirmers in a fluid otherwise at rest, contained in a cube with periodic boundary conditions, is dynamically computed, for random initial positions and orientations. The computation utilizes a database of pairwise interactions that has been constructed by the boundary element method. In the case of (non-bottom-heavy) squirmers, both the translational and the orientational spreading of squirmers is correctly described as a diffusive process over a sufficiently long time scale, even though all the movements of the squirmers were deterministically calculated. Scaling of the results on the assumption that the squirmer trajectories are unbiased random walks is shown to capture some but not all of the main features of the results. In the case of (bottom-heavy) squirmers, the diffusive behaviour in squirmers' orientations can be described by a biased random walk model, but only when the effect of hydrodynamic interaction dominates that of the bottom-heaviness. The spreading of bottom-heavy squirmers in the horizontal directions show diffusive behaviour, and that in the vertical direction also does when the average upward velocity is subtracted. The rotational diffusivity in this case, at a volume fractionc=0.1, is shown to be at least as large as that previously measured in very dilute populations of swimming algal cells (Chlamydomonas nivalis).
Prevalence and severity of external auditory exostoses in breath-hold divers
Authors: Sheard P W , Doherty M
Published: March 2008

Objective:

To explore the prevalence and severity of external auditory exostoses in a population of experienced breath-hold divers, and to compare these to the same parameters within surfing and self-contained underwater breathing apparatus diving populations.

Design:

A stepwise, multiple regression analysis of cross-sectional data examining the relative contributions of sea surface temperature, latitude of exposure and years of exposure to the prevalence and severity of stenosis due to external auditory exostoses. A chi-square analysis of the prevalence and severity of external auditory exostosis stenosis in the breath-hold divers was compared with previously published data for surfers and self-contained underwater breathing apparatus divers.

Subjects:

Seventy-six male and thirty-five female breath-hold divers attending an international ‘freedive’ competition completed a questionnaire describing aquatic sports habits, geography of participation and symptomatology. Those completing the questionnaire (111/154 attendees) were examined otoscopically for evidence of external auditory exostoses. Images were digitally recorded, scored and graded.

Results:

Exostoses were evident in 87.7 per cent of the 204 ears scored and graded for severity of stenosis due to external auditory exostoses. The prevalence of exostoses was no different from that found in previous studies of surfers and self-contained underwater breathing apparatus divers (p = 0.101). However, the pattern of affliction was more similar to that found in surfers. The severity of exostoses was significantly less than that found in surfing populations (p ≤ 0.001 to 0.007), but greater than that found in self-contained underwater breathing apparatus diving populations (p ≤ 0.001). Sea surface temperature at the location of open-water exposure was the most significant predictor of the prevalence and severity of external auditory exostoses in breath-hold divers (p = 0.019).

Conclusion:

The prevalence and severity patterns of stenosis due to external auditory exostoses in breath-hold divers are more similar to previously published results for surfing populations than to previously published results for self-contained underwater breathing apparatus diving populations. In breath-hold divers, sea surface temperature is the strongest predictor of severity of stenosis due to external auditory exostoses.
Radiographic properties of injected calcium hydroxylapatite: potential false positive findings on positron emission tomography
Authors: Damrose E J
Published: March 2008

Objectives:

To describe the positron emission tomography and computed tomography features of injected calcium hydroxylapatite, and to discuss how these may be mistaken for malignancy.

Case report:

Positron emission tomography is now readily employed in the staging and monitoring of patients with head and neck carcinoma. Concomitant with the growing use of this modality has been the increasing popularity of injected calcium hydroxylapatite to treat glottic incompetence secondary to vocal fold paralysis or following partial laryngectomy. A patient developed aspiration following near-total laryngectomy and subsequently underwent injection of calcium hydroxylapatite, with effective resolution of the aspiration. The patient underwent positron emission tomography scanning as part of routine tumour surveillance; this showed intense tracer uptake at the site of injection, and this pattern persisted for one year following injection.

Conclusions:

As injectable calcium hydroxylapatite becomes more widely used, especially in the treatment of patients with a history of head and neck cancer, physicians should be aware it may cause a potentially misleading, false positive positron emission tomography finding.