bluuebunny/crossref_metadata_2025 huggingface dataset:
TEM study of c‐plane GaN layers grown on γ‐LiAlO2(100)
Authors: Mogilatenko A. , Neumann W. , Richter E. , Weyers M. , Velickov B. , Uecker R.
Published: September 2008

Freestanding c‐plane GaN layers were grown by hydride vapor phase epitaxy on γ‐LiAlO2(100) substrates. The layers appear transparent and colorless. However, they contain a large number of dodecagonal pinholes (V‐pits), which are surrounded by brownish GaN pyramids. It is shown that the V‐pit formation occurs at the top of N‐polar inversion domains, which appear in the Ga‐polar GaN matrix. The GaN layers contain threading dislocations, which are partly attracted to the V‐pit surface in order to minimize the dislocation energy. The appearance of brown GaN pyramids around the V‐shaped pinholes seems to be a direct consequence of impurity incorporation, which might stem from the LiAlO2 substrate. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Involvement of the Bcl‐2 Family Members in Pinus massoniana Bark Extract induced Apoptosis in HeLa Cells
Authors: Ma Hongling , Lai Fei , Xie Heng , Wang Jinfa , Wang Hongbin
Published: September 2008

Pinus massoniana bark extract (PMBE) contains a variety of flavonoids whose antioxidant properties have been confirmed in vitro. This study was undertaken to evaluate the cytotoxic effects and the mechanism of cell death on the PMBE‐treated human cervical cancer cell line, HeLa. PMBE treatment led to cell growth inhibition in a dose‐ and time‐dependent manner, and PMBE‐induced apoptosis was confirmed by DAPI staining, TUNEL assays and sub‐G1 phase accumulation. Cell cycle was also arrested in G2/M phase. Immunoblotting analysis showed that cytochrome c was released, the protein expression of Bax was increased, the protein expression of Bcl‐2 was down‐regulated and caspase‐9 and ‐3 were activated in PMBE‐treated HeLa cells. Taken together, PMBE inhibited proliferation, induces apoptosis and causes cell cycle arrest in HeLa cells, indicating that PMBE may be a potential therapeutic agent for cancer. Copyright © 2008 John Wiley & Sons, Ltd.
The Inhibition of Free Radical Generation by Preparations of Harpagophytum procumbens in vitro
Authors: Grant Louise , McBean Douglas E. , Fyfe Lorna , Warnock A. Mary
Published: September 2008

Harpagophytum procumbens (Hp), commonly known as Devil's Claw has been used as a traditional treatment for a variety of illnesses for centuries. Since the early twentieth century, it has become a popular antiinflammatory and analgesic preparation amongst European herbalists for supportive or adjuvant treatment of degenerative joint diseases. Extracts of Hp tubers have demonstrated antiinflammatory and analgesic effects in animal models of inflammation and in human trials. The mechanism(s) of action responsible for these attributes, however, remain to be elucidated. Reactive oxygen species generated in acute and chronic inflammatory diseases are known to be cytotoxic and can cause tissue damage. In this study, a root tuber extract (Hp extract) and commercially available tincture (Hp tincture) were investigated for antioxidant characteristics using in vitro test systems. Both preparations were found to effectively scavenge DPPH radical, inhibit nitrite levels in supernatants harvested from LPS‐stimulated RAW 264.7 macrophages, and cause dose‐dependent suppressions in the detection of fMLP‐ and AA‐induced neutrophil MPO. The antioxidant effects demonstrated for both preparations of Hp may contribute to the antiinflammatory and analgesic properties observed for the plant. Copyright © 2008 John Wiley & Sons, Ltd.
Genotoxicity of Achillea millefolium essential oil in diploid cells of Aspergillus nidulans
Authors: Sant'Anna Juliane Rocha de , Franco Claudinéia Conationi da Silva , Miyamoto Claudia Tiemi , Cunico Miriam Machado , Miguel Obdulio Gomes , Côcco Lílian Cristina , Yamamoto Carlos Itsuo , Junior Cirino Corrêa , Castro‐Prado Marialba Avezum Alves de
Published: September 2008

The essential oil of Achillea millefolium is commonly used in folk medicine for the treatment of several diseases and has been demonstrated previously to exert an in vitro antimicrobial activity against human pathogens. Current study investigates the genotoxic activity of A. millefolium oil. The oil's major constituents are: chamazulene (42.15%), sabinene (19.72%), terpin‐4‐ol (5.22%), β‐caryophyllene (4.44%) and eucalyptol (3.10%), comprising 74.63% of the total. The oil's genotoxic evaluation was performed at concentrations of 0.13 µL/mL, 0.19 µL/mL and 0.25 µL/mL with a heterozygous diploid strain of Aspergillus nidulans, named A757//UT448, with green conidia. A statistically significant increasing number of yellow and white mitotic recombinants, per colony, of the diploid strain was reported after oil treatment with 0.19 µL/mL and 0.25 µL/mL concentrations. The genotoxicity of the oil was associated with the induction of mitotic non‐disjunction or crossing‐over by oil. Copyright © 2008 John Wiley & Sons, Ltd.
Balanced boundary layers used in hurricane models
Authors: Smith Roger K. , Montgomery Michael T.
Published: September 2008

We examine the formulation and accuracy of various approximations made in representing the boundary layer in simple axisymmetric hurricane models, especially those that assume strict gradient wind balance in the radial direction. Approximate solutions for a steady axisymmetric slab boundary‐layer model are compared with a full model solution. It is shown that the approximate solutions are generally poor in the inner core region of the vortex, where the radial advection term in the radial momentum equation is important and cannot be neglected. These results affirm some prior work and have implications for a range of theoretical studies of hurricane dynamics, including theories of potential intensity, that employ balanced boundary‐layer formulations. Copyright © 2008 Royal Meteorological Society
A cirrus cloud scheme for general circulation models
Authors: Kärcher B. , Burkhardt U.
Published: September 2008

A statistical cloud scheme for non‐convective cirrus formed by homogeneous freezing of supercooled aerosols is presented. As large‐scale cirrus clouds exhibit metastable thermodynamic states and have long lifetimes, a fully prognostic approach is developed. The scheme is based on separate probability distribution functions of total water representing clear‐sky and in‐cloud conditions. These distributions are based on in situ observations and have few degrees of freedom so that they can be used in forecast and climate models. Predictive equations are derived for horizontal cloud fraction and mixing ratios of grid‐mean water vapour and ice water, in‐cloud water vapour and ice crystal number. The scheme allows sub‐ and supersaturations with respect to ice to occur in cloud‐free air and inside cirrus, and produces nucleated ice crystal concentrations and sizes in good agreement with observations, an important prerequisite for an improved treatment of cirrus cloud radiative properties. Implementation in general circulation models, open issues and future research avenues are discussed. Copyright © 2008 Royal Meteorological Society
Non‐normal growth in symmetric shear flow
Authors: Heifetz Eyal , Farrell Brian F.
Published: September 2008

An analysis of symmetric instability from the perspective of Generalized Stability Theory is presented. For Richardson number smaller than one, the optimal growth exceeds that predicted by normal mode analysis yielding potentially a much faster generation of slantwise convection. In both normal and non‐normal evolution, the parcel trajectory remains close to the isentropes and energy growth results primarily from the vertical Reynolds stress term in the energy equation. The large non‐normal growth obtained results from the optimal perturbations having parcel trajectories in the mean shear plane, in the initial stage, that maximize the growth by Reynolds stress. This plane is perpendicular to the plane of the isentropes and the absolute momentum isolines, usually associated with slantwise convection. For Richardson number larger than unity, transient growth results primarily from the meridional heat flux term in the energy equation, however this growth is relatively small. Copyright © 2008 Royal Meteorological Society
Analysis of additive risk model with high‐dimensional covariates using partial least squares
Authors: Zhao Yichuan , Zhou Yue , Zhao Meng
Published: September 2008

In this paper, we construct a partial additive regression (PAR) model to predict the survival times of cancer patients based on microarray gene expression data with right censoring. The area under time‐dependent receiver operating characteristic curve is used as a model evaluation criterion. We conduct a simulation study to compare the proposed method with other methods, i.e. partial Cox regression and supervised principal component analysis. Two data sets of breast cancer and diffuse large B‐cell lymphoma are analyzed to illustrate our procedure. The outcome indicates great predictive performance on both dimension reduction and predictive performance of the proposed PAR model. Copyright © 2008 John Wiley & Sons, Ltd.
Approaches to handling data when a phase II trial deviates from the pre‐specified Simon's two‐stage design
Authors: Wu Yujun , Shih Weichung J.
Published: September 2008

Simon's ‘optimal’ and ‘minimax’ two‐stage designs are common methods for conducting phase IIA studies investigating new cancer therapies. However, these designs are rather rigid in their settings because of the pre‐specified rejection rules and fixed sample sizes at each stage. In practice, we often encounter the problem that a study is unable to adhere to the event number and sample sizes of the original two‐stage design. In this paper, we consider some approaches in handling situations where deviations or interruptions from the original Simon's two‐stage design occur because recruitment of patients is slower than expected. We consider four scenarios and use conditional probabilities to address the issues commonly inquired by the scientific review board. We also discuss how to report p‐values in these situations. Copyright © 2008 John Wiley & Sons, Ltd.
Multivariate modelling of infectious disease surveillance data
Authors: Paul M. , Held L. , Toschke A. M.
Published: September 2008

This paper describes a model‐based approach to analyse multivariate time series data on counts of infectious diseases. It extends a method previously described in the literature to deal with possible dependence between disease counts from different pathogens. In a spatio‐temporal context it is proposed to include additional information on global dispersal of the pathogen in the model. Two examples are given: the first describes an analysis of weekly influenza and meningococcal disease counts from Germany. The second gives an analysis of the spatio‐temporal spread of influenza in the U.S.A., 1996–2006, using air traffic information. Maximum likelihood estimates in this non‐standard model class are obtained using general optimization routines, which are integrated in the R packagesurveillance. Copyright © 2008 John Wiley & Sons, Ltd.
Outside directors' industry‐specific experience and firms' liability of newness
Authors: Kor Yasemin Y. , Misangyi Vilmos F.
Published: September 2008

This study makes a contribution to the growing literature on the board's resource provision role by examining a specific type of resource provision (i.e., industry experience supplementing) and demonstrating the criticality of the liabilities of newness to this particular role. In this study, we find that among younger entrepreneurial firms, a dearth of top management industry experience is offset by the presence of outside directors with significant managerial industry experience, providing evidence of experience supplementing by outside directors. Our study highlights that the notion of experience supplementing at the upper echelons prevails in young firms as they try to alleviate the burdens of the liability of newness. Experience supplementing underscores board‐management collaboration during early years of firm development. Copyright © 2008 John Wiley & Sons, Ltd.
Does it pay to be different? An analysis of the relationship between corporate social and financial performance
Authors: Brammer Stephen , Millington Andrew
Published: September 2008

This study explores the relationship between corporate social performance (CSP) and corporate financial performance (CFP) within the context of a specific component of CSP: corporate charitable giving. A model of the determinants of the extent of corporate charitable giving is estimated and used as the basis of a classification that groups firms according to the difference between their actual and their predicted intensity of gift giving. The financial performance attributes of the classification are explored. We found that firms with both unusually high and low CSP have higher financial performance than other firms, with unusually poor social performers doing best in the short run and unusually good social performers doing best over longer time horizons. Copyright © 2008 John Wiley & Sons, Ltd.
A conceptual model for designing adaptive human–computer interfaces using the living systems theory
Authors: Letsu‐Dake E. , Ntuen C. A.
Published: September 2008

This paper discusses the application of the living systems theory (LST) to human–computer interface (HCI) design. It introduces LST as a paradigm for HCI design that can produce interfaces with self‐learning and adaptive capabilities. From a biological system perspective, LST framework provides an emergence property to HCI, an attribute required to encourage self‐organized behaviours during user interaction with computers. A sample interface in the domain of power systems information management is used to demonstrate the efficacy of LST as an adaptive HCI design tool. It is shown that the application of LST will not only provide a robust framework for designing HCI, but can also allow for real‐time performance of the adaptive processes of the interface agents. Copyright © 2008 John Wiley & Sons, Ltd.
Effective instruction and college student persistence: Some new evidence
Authors: Pascarella Ernest T. , Seifert Tricia A. , Whitt Elizabeth J.
Published: September 2008

The research presented here indicates that exposure to organized and clear classroom instruction may have positive net effects on the probability of returning to an institution for the second year of college.
Toward a scholarship of practice centered on college student retention
Authors: Braxton John M.
Published: September 2008

This chapter provides support for a scholarship of practice focused on the translation of research findings into recommendations for policy and practice designed to increase institutional rates of student retention.
Design load definition by LEXPOL
Authors: von Collani Elart , Binder A. , Sans W. , Heitmann A. , Al‐Ghazali K.
Published: September 2008

The predicted long‐term loads for wind turbines determine turbine cost and reliability; and therefore, the definition of the maximum loads, which might realistically occur during the turbine's lifetime, are of considerable importance. The difficulty with predicting the extreme loads derives from the involved uncertainties. Uncertainty refers to the wind and materializes in variability in the sense that the wind speed and the load magnitude varying in time, even if the meteorologic conditions do not change. Therefore, the problem is to describe the variability of the loads in a way that allows reliable, and at the same time accurate, predictions of the maximum loads that the turbines have to withstand. The predictions must have a specified reliability, as otherwise the inherent risks would be unknown, and they should be accurate, as otherwise the cost of manufacturing the turbines would become excessive.

LEXPOL® is based on recent results concerning the stochastic handling of uncertainty, resulting in sets of probability distributions for each considered wind bin. These sets of probability distributions cover the unknown true distribution rather than approximate it by a fitted distribution as it is the case in conventional approaches. The coverage refers to uncertainty measured by entropy and some characteristic distributional properties. Thus, the stochastic models allow reliable and – with respect to the available knowledge – most accurate predictions. Based on the models for specified values of the mean wind speed and the turbulence, prediction procedures for the extreme loads are developed in the unconditional case as well as for long periods. Copyright © 2008 John Wiley & Sons, Ltd.
Peritoneal dialysis prescription in children: bedside principles for optimal practice
Authors: Fischbach Michel , Warady Bradley A.
Published: September 2008

There is no unique optimal peritoneal dialysis prescription for all children, although the goals of ultrafiltration and blood purification are universal. In turn, a better understanding of the physiology of the peritoneal membrane, as a dynamic dialysis membrane with an exchange surface area recruitment capacity and unique permeability characteristics, results in the transition from an empirical prescription process based on clinical experience alone to the potential for a personalized prescription with individually adapted fill volumes and dwell times. In all cases, the prescribed exchange fill volume should be scaled for body surface area (ml/m2), and volume enhancement should be conducted based on clinical tolerance and intraperitoneal pressure measurements (IPP; cmH2O). The exchange dwell times should be determined individually and adapted to the needs of the patient, with particular attention to phosphate clearance and ultrafiltration capacity. The evolution of residual kidney function and the availability of new, more physiologic, peritoneal dialysis fluids (PDFs) also influence the prescription process. An understanding of all of these principles is integral to the provision of clinically optimal PD.
Multiple informants in the assessment of psychological, behavioral, and academic correlates of bullying and victimization in middle school
Authors: Wienke Totura Christine M. , Green Amy E. , Karver Marc S. , Gesten Ellis L.
Published: September 2008

The present study assessed agreement between student self‐report and teacher ratings of bullying and victimization relative to psychological, behavioral, and academic correlates. Middle school students (N = 1442) and teachers completed surveys evaluating peer relationships and psychosocial adjustment. Analyses of variance and logistic regressions were used to examine rater agreement on bullying/victimization and adjustment among groups (bullies, victims, bully/victims, and uninvolved) identified by rater (student self‐report only, teacher‐report only, concordant reports, and controversial reports). Concordant and controversial groups had among the greatest psychosocial and academic difficulties. Student learning difficulties and moodiness interacted with teacher reports of bullying and victimization, respectively, with agreement between teacher and student self reports of bullying greater at higher levels of learning problems and agreement for victimization lower at higher levels of moodiness. The results indicate biases in rater perspective of student behavior and continue to support the need for multiple raters of student functioning.
Urinary neutrophil gelatinase associated lipocalin (NGAL), a marker of tubular damage, is increased in patients with chronic heart failure
Authors: Damman Kevin , van Veldhuisen Dirk J. , Navis Gerjan , Voors Adriaan A. , Hillege Hans L.
Published: September 2008

Renal impairment, as measured by reduced glomerular filtration rate (GFR) and increased urinary albumin excretion (UAE), is prevalent in patients with chronic heart failure (CHF) and is associated with reduced survival. The prevalence of structural tubular damage in CHF is unknown. We investigated 90 CHF patients and 20 age and sex matched healthy controls, and determined estimated GFR, UAE, N terminal‐pro brain natriuretic peptide (NT‐proBNP) and urinary neutrophil gelatinase associated lipocalin (NGAL) as a marker for tubular damage. CHF patients had significantly lower averaged estimated GFR (64 ± 17 vs 90 ± 12 mL/min/1.73 m2, P<0.0001), but higher NT‐proBNP and UAE levels (both P<0.0001). Median urinary NGAL levels were markedly increased in CHF patients compared to controls (175 (70–346) vs 37 (6–58) μg/gCr, P<0.0001). Both serum creatinine (r=0.26, P=0.006) and eGFR (r=−0.29, P=0.002) were significantly associated with urinary NGAL levels as were NT‐proBNP and UAE but to a lesser extent. In conclusion, renal impairment in CHF patients is not only characterised by decreased eGFR and increased UAE, but also by the presence of tubular damage, as measured by increased urinary NGAL concentrations.
Synergistic interaction of gabapentin with tiagabine in the formalin test in mice: An isobolographic analysis
Authors: Luszczki Jarogniew J. , Kolacz Agnieszka , Czuczwar Miroslaw , Przesmycki Krzysztof , Czuczwar Stanislaw J.
Published: September 2008

The aim of this study was to determine the analgesic effect of gabapentin and tiagabine – two antiepileptic drugs, administered alone and in combination at the fixed‐ratio of 1:1, in two phases of the formalin test in mice. Log‐probit analysis was used to evaluate dose–response effects and calculate the ED50values for gabapentin, tiagabine, and their combination at the fixed‐ratio of 1:1 in the phases I and II of the formalin test in mice. The types of interactions between both antiepileptic drugs were characterized using the isobolographic analysis.

Results indicated that gabapentin and tiagabine produced the antinociceptive effect in both phases of the formalin test. The ED50values for gabapentin and tiagabine, administered singly, in the phase I of the formalin test were 29.59 and 2mg/kg, whereas in the phase II of the formalin test were 8.22 and 0.50mg/kg, respectively. With isobolography, the ED50mixvalues at the fixed‐ratio combination of 1:1 were 7.30mg/kg (phase I) and 0.48mg/kg (phase II), indicating both additive and supra‐additive (synergistic) interactions between gabapentin and tiagabine in the formalin test in mice.

In conclusion, the combination of gabapentin with tiagabine at the fixed‐ratio of 1:1 exerted additive interaction in the phase I and synergistic interaction in the phase II of the formalin test in mice. If the results from this study could be extrapolated to clinical settings, the combination of tiagabine with gabapentin might be beneficial in the pain relief in humans.
Diminished drug transport and augmented radiation sensitivity caused by loss of RLIP76
Authors: Singhal Sharad S. , Yadav Sushma , Singhal Jyotsana , Sahu Mukesh , Sehrawat Archana , Awasthi Sanjay
Published: September 2008

This study was undertaken to characterize the consequences of Ral‐interacting protein (RLIP76)‐loss with respect to drug resistance, transport, radiation resistance, and alternative transport mechanisms in mouse embryonic fibroblasts (MEFs). MEFs were derived from RLIP76+/+, RLIP76+/− and RLIP76−/− mice. The transport of doxorubicin (DOX), colchicine (COL), leukotriene C4 and dinitrophenyl S‐glutathione (DNP‐SG) was analyzed in inside‐out vesicles (IOVs) prepared from MEFs. We used immuno‐titration of transport activity to determine the contribution of RLIP76, MRP1, and p‐glycoprotein (Pgp) towards total transport activity. Loss of RLIP76 alleles resulted in significant sensitization to radiation, DOX, cisplatin, and vinorelbine (VRL). In IOVs prepared from MEFs, we observed a stepwise loss of transport activity. Loss of RLIP76 confers sensitivity to xenobiotics and radiation due to the loss of a common transport mechanism for glutathione–electrophile conjugates and xenobiotics.
Nuclear matrix contains novel WD‐repeat and disordered‐region‐rich proteins
Authors: Ishii Kohei , Hirano Yasuhiro , Araki Nanase , Oda Toshiyuki , Kumeta Masahiro , Takeyasu Kunio , Furukawa Kazuhiro , Horigome Tsuneyoshi
Published: September 2008

To find novel proteins predicted to participate in the formation of nuclear bodies, nuclear speckles, and nuclear macro‐protein complexes, we applied proteome analysis to a HeLa cell nuclear matrix fraction. Proteins in the fraction were separated by SDS–PAGE, digested with trypsin, and analyzed by nanoflow liquid chromatography–iontrap‐tandem mass spectrometry. Three hundred and thirty three proteins including 39 novel ones were identified. Seven WD‐repeat proteins and 16 disordered region‐rich proteins, which act frequently as scaffolding proteins for macro‐protein complexes, were found amongst the novel proteins.
Epigenetic Changes in Tumor Suppressor Genes, P15, P16, APC‐3 and E‐cadherin in Body Fluid
Authors: Chen Mei‐Ling , Chang Julia Huei‐Mei , Yeh Kun‐Tu , Chang Ya‐Sian , Chang Jan‐Gowth
Published: September 2008

The inactivation of tumor suppressor genes by promoter methylation plays an important role in the development of cancers; it can also be used as a marker to distinguish cancerous cells from non‐cancer cells. In this study, we investigated the aberrant methylation profile of the tumor suppressor genes P15, P16, APC and E‐cadherin in the cells of body fluid. A methylation‐specific polymerase chain reaction was performed in 31 cases of malignant effusion and 39 cases of nonmalignant effusion. Aberrant promoter methylation of P15, P16, APC and E‐cadherin genes was seen in 0%, 25.8%, 35.5% and 6.5% of malignant effusion cases, respectively, whereas the frequencies were 0%, 2.6%, 2.6% and 0%, respectively, for negative control effusion. There were statistically significant differences in the aberrant methylation of P16 (p = 0.008) and APC (p = 0.018) genes between cases of malignant effusion and controls. Methylation of one of three genes (P16, E‐cadherin, APC) was found in 14 out of 31 (45.2%) cases of malignant effusion, and in two out of 39 (5.1%) cases of non‐malignant effusion (p = 0.000004). Concurrent methylation was found in nine out of 31 (29%) cases of malignant effusion, but in no non‐malignant effusion sample. From these results, we suggest that methylation‐specific polymerase chain reaction to analyze the promoters of tumor suppressor genes can distinguish between malignant effusion and benign effusion, and may help cytologists to make more accurate diagnoses.
The Winter Procedure as Management for Prolonged Low‐Flow Priapism: A Case Report
Authors: Hsiao Hsi‐Lin , Wang Chii‐Jye , Li Wei‐Ming , Chang Tu‐Hao , Li Yung‐Chin , Huang Chun‐Hsiung
Published: September 2008

Priapism is a prolonged penile erection that is not associated with sexual stimulation. Although the time course has not been formally defined, it is usually considered to be one that lasts for more than 4–6 hours. Low‐flow (ischemic) priapism is usually associated with sickle cell disease, hemoglobinopathies, neoplastic syndrome, anticoagulant therapy, psychotropic medication or idiopathic causes. Here, we report a case of prolonged low‐flow priapism lasting for 2 weeks, which was successfully treated with the Winter procedure after several attempts of conservative treatment. Although the potency remains unclear and the patient needs a longer period of follow‐up, the case reported here still shows that prolonged low‐flow priapism can be successfully treated with the Winter procedure when conservative treatments fail.
EXISTENCE OF POSITIVE EVANESCENT SOLUTIONS TO SOME QUASILINEAR ELLIPTIC EQUATIONS
Authors: MUSTAFA OCTAVIAN G.
Published: September 2008

We establish that the elliptic equationdefined in an exterior domain of ℝn,n≥3, has a positive solution which decays to 0 as$\vert x\vert \rightarrow +\infty $under quite general assumptions uponfandg.
POSITIVE PERIODIC SOLUTIONS OF SECOND-ORDER DIFFERENTIAL EQUATIONS WITH SINGULARITIES
Authors: LI HONG-XU
Published: September 2008

In this work, we consider the periodic boundary value problem where a,c∈L1(0,T) and f is a Carathéodory function. An existence theorem for positive periodic solutions is proved in the case where the associated Green function is nonnegative. Our result is valid for systems with strong singularities, and answers partially the open problem raised in Torres [‘Weak singularities may help periodic solutions to exist’, J. Differential Equations232 (2007), 277–284].
Nonlinear evolution of the Richtmyer–Meshkov instability
Authors: HERRMANN MARCUS , MOIN PARVIZ , ABARZHI SNEZHANA I.
Published: September 2008

We report analytical and numerical results describing the dynamics of the two-dimensional coherent structure of bubbles and spikes in the Richtmyer–Meshkov instability for fluids with a finite density ratio. The theory accounts for the non-local properties of the interface evolution, and the simulations treat the interface as a discontinuity. Good agreement between the analytical and numerical results is achieved. To quantify accurately the interface dynamics in the simulations, new diagnostics and scalings are suggested. The velocity at which the interface would move if it were ideally planar is used to set the flow time scale as well as the reference point for the bubble (spike) position. The data sampling has high temporal resolution and captures the velocity oscillations caused by sound waves. The bubble velocity and curvature are both monitored, and the bubble curvature is shown to be the relevant diagnostic parameter. According to the results obtained, in the nonlinear regime of the Richtmyer–Meshkov instability the bubbles flatten and decelerate, and the flattening of the bubble front indicates the multiscale character of the coherent dynamics.
Endothermic and exothermic chemically reacting plumes
Authors: CONROY DEVIN T. , SMITH STEFAN G. LLEWELLYN
Published: September 2008

We develop a model for a turbulent plume in an unbounded ambient that takes into account a general exothermic or endothermic chemical reaction. These reactions can have an important effect on the plume dynamics since the entrainment rate, which scales with the vertical velocity, will be a function of the heat release or absorption. Specifically, we examine a second-order non-reversible reaction, where one species is present in the plume from a pure source and the other is in the environment. For uniform ambient density and species fields the reaction has an important effect on the deviation from pure plume behaviour as defined by the source parameter Γ. In the case of an exothermic reaction the density difference between the plume and the reference density increases and the plume is ‘lazy’, whereas for an endothermic reaction this difference decreases and the plume is more jet-like. Furthermore, for chemical and density-stratified environments, the reaction will have an important effect on the buoyancy flux because the entrainment rate will not necessarily decrease with distance from the source, as in traditional models. As a result, the maximum rise height of the plume for exothermic reactions may actually decrease with reaction rate if this occurs in a region of high ambient density. In addition, we investigate non-Boussinesq effects, which are important when the heat of reaction is large enough.
Low-dimensional characteristics of a transonic jet. Part 1. Proper orthogonal decomposition
Authors: TINNEY C. E. , GLAUSER M. N. , UKEILEY L. S.
Published: September 2008

An experimental investigation concerning the most energetic turbulent features of the flow exiting from an axisymmetric converging nozzle at Mach 0.85 and ambient temperature is discussed using planar optical measurement techniques. The arrangement of the particle image velocimetry (PIV) system allows for all three components of the velocity field to be captured along the (r, θ)-plane of the jet at discrete streamwise locations betweenx/D=3.0 and 8.0 in 0.25 diameter increments. The ensemble-averaged (time-suppressed) two-point full Reynolds stress matrix is constructed from which the integral eigenvalue problem of the proper orthogonal decomposition (POD) is applied using both scalar and vector forms of the technique. A grid sensitivity study indicates that the POD eigenvalues converge safely to within 1% of their expected value when the discretization of the spatial grid is less than 30% of the integral length scale or 10% of the shear-layer width. The first POD eigenvalue from the scalar decomposition of the streamwise component is shown to agree with previous investigations for a range of Reynolds numbers and Mach numbers with a peak in azimuthal mode 5 atx/D=3.0, and a gradual shift to azimuthal mode 2 byx/D=8.0. The eigenvalues from the scalar POD of the radial and azimuthal components are shown to be much lower-dimensional with most of their energy residing in the first few azimuthal modes, that is modes 0, 1 and 2, with little change in the relative energies along the streamwise direction. From the vector decomposition, the azimuthal eigenspectra of the first two POD modes shift from a peak in azimuthal mode 5 atx/D=3.0, followed by a gradual decay to azimuthal mode 2 atx/D=8.0, the differences in the peak energies being very subtle. The conclusion from these findings is that when the Mach number is subsonic and the Reynolds number sufficiently large, the structure of the turbulent jet behaves independently of these factors.
Modelling the breakup of solid aggregates in turbulent flows
Authors: BÄBLER MATTHÄUS U. , MORBIDELLI MASSIMO , BAŁDYGA JERZY
Published: September 2008

The breakup of solid aggregates suspended in a turbulent flow is considered. The aggregates are assumed to be small with respect to the Kolmogorov length scale and the flow is assumed to be homogeneous. Further, it is assumed that breakup is caused by hydrodynamic stresses acting on the aggregates, and breakup is therefore assumed to follow a first-order kinetic whereKB(x) is the breakup rate function andxis the aggregate mass. To modelKB(x), it is assumed that an aggregate breaks instantaneously when the surrounding flow is violent enough to create a hydrodynamic stress that exceeds a critical value required to break the aggregate. For aggregates smaller than the Kolmogorov length scale the hydrodynamic stress is determined by the viscosity and local energy dissipation rate whose fluctuations are highly intermittent. Hence, the first-order breakup kinetics are governed by the frequency with which the local energy dissipation rate exceeds a critical value (that corresponds to the critical stress). A multifractal model is adopted to describe the statistical properties of the local energy dissipation rate, and a power-law relation is used to relate the critical energy dissipation rate above which breakup occurs to the aggregate mass. The model leads to an expression forKB(x) that is zero below a limiting aggregate mass, and diverges forx→ ∞. When simulating the breakup process, the former leads to an asymptotic mean aggregate size whose scaling with the mean energy dissipation rate differs by one third from the scaling expected in a non-fluctuating flow.
Spectral properties and universal behaviour of advecting–diffusing scalar fields in finite-length channels
Authors: GIONA M. , CERBELLI S. , CRETA F.
Published: September 2008

This paper analyses the relaxation towards the steady state of an advecting–diffusing field in a finite-length channel. The dominant eigenvalue, −-ΛF, of the advection–diffusion operator provides the slowest relaxation time scale for achieving steady state in open flow devices. We focus on parallel flows and analyse how ΛF depends on the velocity profile and the molecular diffusivity. As a result of the universal localization features of the eigenfunction associated with ΛF, we find that ΛF can be predicted analytically based on the local behaviour of the velocity profile near the stagnation points. Microfluidic applications of the theory are also addressed.
Vortex motion in doubly connected domains
Authors: ZANNETTI L. , GALLIZIO F. , OTTINO G. M.
Published: September 2008

The unsteady two-dimensional rotational flow past doubly connected domains is analytically addressed. By concentrating the vorticity in point vortices, the flow is modelled as a potential flow with point singularities. The dependence of the complex potential on time is defined according to the Kelvin theorem. The general case of non-null circulations around the solid bodies is discussed. Vortex shedding and time evolution of the circulation past a two-element airfoil and past a two-bladed Darrieus turbine are presented as physically coherent examples.
Finite-wavelength scattering of incident vorticity and acoustic waves at a shrouded-jet exit
Authors: SAMANTA ARNAB , FREUND JONATHAN B.
Published: September 2008

As the vortical disturbances of a shrouded jet pass the sharp edge of the shroud exit some of the energy is scattered into acoustic waves. Scattering into upstream-propagating acoustic modes is a potential mechanism for closing the resonance loop in the ‘howling’ resonances that have been observed in various shrouded jet configurations over the years. A model is developed for this interaction at the shroud exit. The jet is represented as a uniform flow separated by a cylindrical vortex sheet from a concentric co-flow within the cylindrical shroud. A second vortex sheet separates the co-flow from an ambient flow outside the shroud, downstream of its exit. The Wiener–Hopf technique is used to compute reflectivities at the shroud exit. For some conditions it appears that the reflection of finite-wavelength hydrodynamic vorticity modes on the vortex sheet defining the jet could be sufficient to reinforce the shroud acoustic modes to facilitate resonance. The analysis also gives the reflectivities for the shroud acoustic modes, which would also be important in establishing resonance conditions. Interestingly, it is also predicted that the shroud exit can be ‘transparent’ for ranges of Mach numbers, with no reflection into any upstream-propagating acoustic mode. This is phenomenologically consistent with observations that indicate a peculiar sensitivity of resonances of this kind to, say, jet Mach number.
Reciprocating procedure device for thyroid cyst aspiration and ablative sclerotherapy
Authors: Sibbitt R R , Palmer D J , Sibbitt W L
Published: September 2008

Most thyroid cysts are benign; however, they require aspiration if symptomatic or atypical on ultrasound scanning, and ablation with ethanol injection if recurrent. We have systematically studied the use of new safety technologies for surgical procedures, which protect both the surgeon and the patient. Here, we describe the use of one such technology, the reciprocating procedure device, which enables simpler, safer, more efficient and less painful thyroid cyst aspiration and therapeutic ablation.
Bilateral profound sudden sensorineural hearing loss presenting a diagnostic conundrum in a child with sickle cell anaemia
Authors: Mace A D , Ferguson M S , Offer M , Ghufoor K , Wareing M J
Published: September 2008

Objective:

To present the first published case of a child with bilateral profound sudden sensorineural hearing loss found in association with sickle cell anaemia, and to demonstrate the importance of early recognition, investigation and empirical treatment of sudden sensorineural hearing loss.

Method:

Case report and review of world literature.

Case report:

The authors present the case of a seven-year-old child with known sickle cell anaemia, who presented with bilateral profound sensorineural hearing loss developing over a period of five days. There was a history of ophthalmological disease in the preceding weeks, and inflammatory markers were raised. The differential diagnosis included a vaso-occlusive or inflammatory aetiology such as Cogan's syndrome, and treatment for both was instigated. Hearing thresholds did not recover, and the patient underwent cochlear implantation 12 weeks later.

Conclusion:

Sudden sensorineural hearing loss has a variable aetiology and is rare in children. Immediate treatment for all possible aetiologies is essential, along with targeted investigations and early referral for cochlear implantation if no recovery is demonstrated.
Quality of life after free-flap tongue reconstruction
Authors: Hartl D M , Dauchy S , Escande C , Bretagne E , Janot F , Kolb F
Published: September 2008

Objective:

To analyse correlations between quality of life measures, aspiration and extent of surgical resection in patients who have undergone free-flap tongue reconstruction.

Patients and methods:

Nine consecutive patients (seven men and two women; average age 51 years) who had been diagnosed with T4a carcinoma of the mobile tongue and/or tongue base and treated by glossectomy, free-flap reconstruction, and either radiation therapy or chemoradiation responded to the European Organization for Research and Treatment of Cancer Head and Neck-35 questionnaire, the performance status scale questionnaire and the hospital anxiety–depression scale questionnaire, an average of 43 months after treatment (range 18–83 months). Aspiration was evaluated by fibre-optic laryngoscopy. Correlations between quality of life domain scores, extent of surgery and the presence of aspiration were evaluated using non-parametric statistical analysis.

Results:

Scores for the swallowing and aspiration domains of the European Organization for Research and Treatment of Cancer Head and Neck-35 questionnaire were significantly correlated with the extent of tongue base resection (Spearman's correlation, p = 0.037 and 0.042, respectively). Despite a strong correlation between the European Organization for Research and Treatment of Cancer Head and Neck-35 questionnaire results and the performance status scale global scores (correlation coefficient = 0.89, p = 0.048), the performance status scale domain scores were not correlated with the extent of tongue resection. Clinically apparent aspiration was not correlated with the extent of tongue resection, nor were the anxiety or depression scores. However, clinically apparent aspiration was significantly related to the swallowing and aspiration domain scores of the European Organization for Research and Treatment of Cancer Head and Neck-35 questionnaire (p = 0.017 in both cases).

Conclusions:

Our results imply that the volume of tongue base resection is a major factor in swallowing- and aspiration-related quality of life following tongue resection and free-flap reconstruction. Free-flap reconstruction does not seem to palliate the effect of the loss of functional tongue base volume, as regards swallowing-related quality of life.
Reproductive biology of Neohelice granulata (Decapoda: Varunidae) in two salt marshes of the estuarine region of the Lagoa dos Patos Lagoon, southern Brazil
Authors: Barutot Roberta A. , D'Incao Fernando , Fonseca Duane B.
Published: September 2008

Neohelice granulata is a crab found in salt marshes and mangroves of the south and south-eastern Atlantic coast of South America. Reproductive biology was studied by taking samples for two years at two salt marshes—‘Prainha’ and ‘Ilha’—in the estuarine region of Patos Lagoon (southern Brazil). Ovigerous females were found most of the year in both salt marshes with average CW ranging from 18.5 (Prainha) to 22.8 mm (Ilha). A significant linear relationship was found between log(CW) and log(number of eggs). Average size at the onset of maturation was 14.9 and 14 mm at Prainha, for males and females, respectively, while at Ilha it was 18.2 and 16.8 mm, for males and females, respectively. Results provided evidence of significant differences in reproductive traits between populations of the two salt marshes. Differences are likely related to the higher organic matter content found in the sediment from Ilha.
Influence of motivation on behaviour in the hermit crab, Pagurus samuelis
Authors: Billock Wendy L. , Dunbar Stephen G.
Published: September 2008

Both the need for shelter and the need for food can be motivations that alter animal behaviour. We tested the hypothesis that the hermit crab, Pagurus samuelis, deprived of food, shells, or both will respond differently from control hermit crabs when presented with food and shells concurrently. We measured the number of contacts made with both food and shells, and time elapsed until hermit crabs either began feeding or inserted into shells. We interpreted making few contacts and initiating behaviour quickly to be an indication of short decision time and high motivation; whereas, making many contacts and having long initiation time indicated a long decision time and low motivation to acquire resources. Control (C) hermit crabs made 72% more contacts with food and 53% more contacts with shells than shell-less (S) crabs. Control hermit crabs also made 34% more contacts with food and 35% more contacts with shells than starved and shell-less (StS) hermit crabs. This suggests that S hermit crabs were more motivated to acquire shells than C crabs. In addition, StS hermit crabs chose to insert into provided shells, while hermit crabs remaining in their shells chose to feed. Results indicate that being shell-less is a stronger motivation than being starved, such that finding shelter takes priority over finding food when both are needed. In rocky intertidal environments, resources such as food and shells are likely to be ephemeral. Hermit crabs that are motivated to make appropriate decisions to acquire specific resources may have a distinct advantage over those that are distracted by numerous objects in their environment.
Cohomology of groups and almost periodic extensions of minimal sets
Authors: Ellis Robert
Published: September 2008

Let ℬ and be minimal flows which are disjoint over their intersection. A dynamical interpretation is given of the groups H1(B/S, C/S) and H2(B/S, C/S), where B and C are the groups of ℬ and respectively, and S is the group of the flow ℬ ⋁ .
Checking ergodicity of some geodesic flows with infinite Gibbs measure
Authors: Rees Mary
Published: September 2008

This paper concerns a problem which arose from a paper of Sullivan. Let Γ be a discrete group of isometries of hyperbolic space Hd+1. We study the question of when the geodesic flow on the unit tangent bundle UT (Hd+1/Γ) of Hd+1/Γ is ergodic with respect to certain natural measures. As a consequence, we study the question of when Γ is of divergence type. Ergodicity when the non-wandering set of UT (Hd+1/Γ) is compact is already known from the theory of symbolic dynamics, due to Bowen, or from Sullivan's work. For such a Γ, we consider a subgroup Γ1 of Γ with Γ/Γ1 ≅ℤυ and prove the geodesic flow on UT (Hd+1/Γ1) is ergodic (with respect to one of these natural measures) if and only if υ ≤ 2.
A C∞ Denjoy counterexample
Authors: Hall Glen Richard
Published: September 2008

In this paper we construct an example of a homeomorphism of the circle onto itself which is C∞, has no periodic points and no dense orbits. Moreover, the homeomorphism will have no more than two points of zero derivative. We alter this example to form a C∞ map of an interval to itself which has homtervals.
On a Bernoulli shift with non-identical factor measures
Authors: Hamachi Toshihiro
Published: September 2008

There exists a Bernoulli shift with non-identical factor measures for which no invariant σ-finite equivalent measure exists.
Periodic orbits of continuous mappings of the circle without fixed points
Authors: Bernhardt Chris
Published: September 2008

Let f be a continuous map of the circle to itself. Let P(f) denote the set of periods of the periodic points. In this paper the set P(f) is studied for functions without fixed points, so 1∉P(f). In particular, it is shown that if s, t are the two smallest integers in P(f) and s and t are relatively prime then αs+βt∈P(f) for any positive integers α and β.
On lattices acting on boundaries of semi-simple groups
Authors: Spatzier R. J.
Published: September 2008

It is shown that for a lattice Γ in a semi-simple group of real rank 1 the action on the boundary always admits an equivariant topological Γ-factor. We also show that there are no such factors for SL (n, ℤ) acting on ℙn−1,n≥3.