bluuebunny/crossref_metadata_2025 huggingface dataset:
Future use of mitocans against tumour‐initiating cells?
Authors: Morrison Brian J. , Andera Ladislav , Reynolds Brent A. , Ralph Stephen J. , Neuzil Jiri
Published: January 2009

Tumour heterogeneity has several important consequences including: (i) making their classification by morphological and genetic analysis more difficult because of the diversity within single tumours and the common majority of cells as the bulk of a tumour will dominate this classification whether or not these cells are critical for diagnosis or treatment, (ii) treatments may fail to eradicate tumours simply by failing to eliminate one of the cell subtypes within the tumour and (iii) differing abilities of the cell subtypes for dissemination and metastasis. Recently, a rare subpopulation of cells within tumours has been described with the ability to initiate and sustain tumour growth, to resist traditional therapies and to allow for secondary tumour dissemination. These cells are termed tumour‐initiating cells (TICs). Understanding tumour heterogeneity will be critical for advancing treatments for cancer that target TIC subpopulations of cells in a tumour able to resist traditional treatments and eliminate them before metastatic disease occurs. It follows that the TICs will be the most important cellular components in the tumour target. Therefore, knowledge of the molecular mechanism(s) of resistance of TICs to treatment and overcoming this problem will be essential in order to develop effective drug strategies for cancer therapy.
The MT pool size ratio and the DTI radial diffusivity may reflect the myelination in shiverer and control mice
Authors: Ou Xiawei , Sun Shu‐Wei , Liang Hsiao‐Fang , Song Sheng‐Kwei , Gochberg Daniel F.
Published: January 2009

A quantitative magnetization transfer (qMT) technique was employed to quantify the ratio of the sizes of the bound and free water proton pools in ex vivo mouse brains. The goal was to determine the pool size ratio sensitivity to myelin. Fixed brains from both shiverer mice and control littermates were imaged. The pool size ratio in the corpus callosum of shiverer mice was substantially lower than that in the control mice, while there was no distinguishable difference in the pool size ratio in the gray matter. These results correlate with diffusion tensor imaging (DTI) derived radial diffusivity which previously was shown to reflect myelin integrity in this animal model. Histological study reveals the presence of myelin in control mice white matter and the absence of myelin in shiverer mice white matter, supporting the qMT and DTI results. Our findings support the view that qMT may be used for estimating myelin integrity. Copyright © 2008 John Wiley & Sons, Ltd.
Trading off SNR and resolution in MR images
Authors: Kale Shoan C. , Chen X. Josette , Henkelman R. Mark
Published: January 2009

With a fixed time to acquire a magnetic resonance (MR) image, time can be spent to acquire better spatial resolution with decrease in signal‐to‐noise ratio (SNR) or decreased resolution with increase in SNR. This resolution/SNR tradeoff at fixed time has been investigated by a visual rater study using images of ex vivo mouse brains. Simulated images with a tradeoff between SNR and resolution were produced from high‐quality, 3D isotropic mouse brain images to emulate shorter constant acquisition times. The tradeoff images spanned a range of SNRs (63–6) and isotropic resolutions (32–81 µm). Fourteen readers identified the image which best displayed neuroanatomy. Additional experiments tested for (i) intra‐observer consistency, (ii) the effect of emulated scan time, and (iii) specifically biased questions pertaining to the perception of neuroanatomy. Optimal anatomical viewing depended primarily on the SNR of the images. Specifically, for fixed imaging time, preference lay in the SNR range of ∼30–35 with strong consistency and there was minimal effect from overall imaging time. Copyright © 2008 John Wiley & Sons, Ltd.
Electrical properties and EMI shielding behavior of highly thermally stable polyaniline/colloidal graphite composites
Authors: Saini Parveen , Choudhary Veena , Dhawan S. K.
Published: January 2009

A hybrid approach has been adopted by using a combination of colloidal graphite (CG) as a conducting filler, 5‐lithium sulfoisophthalic (LiSIPA) acid as a dopant, and polyaniline (PANI) as a matrix to prepare LiSIPA doped PANI–CG composites. The thermal stability (∼300°C) and electrical conductivity (67.4 S/cm at 17.4% CG content) have been improved significantly as compared to PANI doped with conventional inorganic dopants like HCl or H2SO4 (130–150°C). The maximum shielding effectiveness value was found to be −39.7 dB. X‐ray diffraction and infrared spectroscopy showed a systematic shifting of the characteristic peaks and bands with increase in the amount of CG, which indicates significant interaction exists between CG and PANI. The UV–Vis spectra showed the characteristic bands of PANI, with a shift to shorter wavelength with increase in the CG content. The interaction mechanism between doped PANI and CG in the resultant composites has been proposed. Copyright © 2009 John Wiley & Sons, Ltd.
Study on combustion property and synergistic effect of intumescent flame retardant styrene butadiene rubber with metallic oxides
Authors: Liu QingQing , Song Lei , Lu HongDian , Hu Yuan , Wang ZhengZhou , Zhou Shun
Published: January 2009

Effect of metallic oxides on flame retardancy and the thermal stability of styrene butadiene rubber (SBR) composites based on ammonium polyphosphate (APP) and pentaerythritol (PER) was studied by the limiting oxygen index (LOI), UL 94, the cone calorimeter tests, and thermogravimetry analysis (TGA), respectively. Scanning electron microscopy (SEM) and wide‐angle X‐ray diffraction (WAXD) were used to analyze the morphological structure and the component of the residue chars formed from the SBR composites accordingly. The addition of zirconium dioxide (ZrO2) at a loading of 3.4 phr could improve the UL 94 test rating of the composite to V‐0. The TGA data illustrated that the metallic oxides could enhance the thermal stability of the SBR/Intumescent flame retardant additives (IFRs) composites at high temperature and increase the residue. Cone calorimeter test gave much clear evidence that the incorporation of ZrO2 into SBR/IFRs composites resulted in the significant deduction of the heat release rate (HRR) values, and the SEM images showed that the char layers of the composites containing the metallic oxides became more compact. From the WAXD pattern, zirconium phosphate (ZrP2O7) may be formed by the reaction between ZrO2 and APP. Due to the addition of ZrO2 and the formation of ZrP2O7, the flame retardancy of the composite was improved. Copyright © 2009 John Wiley & Sons, Ltd.
Conductive mechanism of antistatic poly(ethylene terephthalate)/ZnOw composites
Authors: Chen Ke , Xiong Chuanxi , Li Liubin , Zhou Liu , Lei Youan , Dong Lijie
Published: January 2009

Antistatic composites of poly(ethylene terephthalate) (PET) and tetrapod‐shaped ZnO whisker (ZnOw), the surface of which was treated with a coupling agent, were prepared by melt‐mixing using a twin screw extruder. The structure and morphology of the blends were examined by FTIR and SEM. Antistatic performance and the effect of ZnOw loading levels were investigated. The conductive mechanism of PET/ZnOw composites is presented, which can be classified into tunnel effect, discharging effect at the pinpoint and conductive network. The simple formula of critical volume fraction (vc) for ZnOw forming conductive network is proposed, based on the actual processing conduction. Comparison of the theory value to the experimental data showed a close agreement. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers
Highly sensitive saturation labeling reveals changes in abundance of cell cycle‐associated proteins and redox enzyme variants during oocyte maturation in vitro
Authors: Berendt Frank J. , Fröhlich Thomas , Bolbrinker Patrick , Boelhauve Marc , Güngör Tuna , Habermann Felix A. , Wolf Eckhard , Arnold Georg J.
Published: January 2009

Oocyte maturation is a complex process and a critical issue in assisted reproduction techniques (ART) in humans and other mammals. We used a sensitive 2‐D DIGE saturation labeling approach including an internal pooled standard for quantitative proteome profiling of immature versus in vitro matured bovine oocytes in six independent samples. The study comprised 48 2D gel images representing 24 DIGE experiments. From 250 ng sample analyzed per gel, quantitative analysis revealed an average of 2244 spots in pH 4–7 images and 1291 spots in pH 6–9 images. Thirty‐eight spots with different intensities were detected in total. Spots of a preparative gel from 2200 oocytes were identified by nano‐LC‐MS/MS analysis. The ten spots which could be unambiguously identified include the Ca2+‐binding protein translationally controlled tumor protein, enzymes of the Krebs and pentose phosphate cycles, clusterin, 14‐3‐3 ϵ, elongation factor‐1 gamma, and redox enzymes such as polymorphic forms of GST Mu 5 and peroxiredoxin‐3. The cellular distribution of two proteins was determined by confocal laser scanning microscopy. The interesting protein candidates identified by this study may help to improve the in vitro maturation process in order to increase the rate of successful in vitro fertilization and other ART in cattle and other mammals.
A comprehensive evaluation of imidazole‐zinc reverse stain for current proteomic researches
Authors: Lin Ching‐Yu , Wang Vinchi , Shui Hao‐Ai , Juang Rong‐Huay , Hour Ai‐Ling , Chen Pei‐Sing , Huang Hui‐Ming , Wu Szu‐Yu , Lee Jen‐Chieh , Tsai Tzung‐Lin , Chen Han‐Min
Published: January 2009

In this paper, we comprehensively evaluated the capability of imidazole‐zinc reverse stain (ZN) in comparative proteomics. Three commonly used protein gel staining methods, including silver (SN), SYPRO Ruby (SR), and CB stain were investigated alongside for comparison purpose. A transparency scanning procedure, which may deliver more even and contrasting gel images, was found best for documenting ZN stained gels. Our results showed that ZN was more sensitive than SN, SR, and CB. It may reveal as few as 1.8 ng of proteins in a gel. Moreover, ZN was found to provide a linear dynamic range of staining for revealing proteins up to 140 ng, and show an insignificant staining preference. To analyze a ZN stained 2‐D gel image that generally comprises an apparent but even background, the Melanie 4 software was found more suitable than others. Furthermore, ZN demonstrated an equivalent or better MS compatibility than the other three staining methods. Intense and comprehensive MS profiles were frequently observed for ZN stained gel spots. Approximate two‐third of ZN stained gel spots were successfully identified for protein identities. Taken together, our results suggest that the prompt, cost effective and versatile ZN is well suited for current proteomic researches.
Yeast protein expression profile during acetic acid‐induced apoptosis indicates causal involvement of the TOR pathway
Authors: Almeida Bruno , Ohlmeier Steffen , Almeida Agostinho J. , Madeo Frank , Leão Cecília , Rodrigues Fernando , Ludovico Paula
Published: January 2009

Although acetic acid has been shown to induce apoptosis in yeast, the exact apoptotic mechanisms remain unknown. Here, we studied the effects of acetic acid treatment on yeast cells by 2‐DE, revealing alterations in the levels of proteins directly or indirectly linked with the target of rapamycin (TOR) pathway: amino‐acid biosynthesis, transcription/translation machinery, carbohydrate metabolism, nucleotide biosynthesis, stress response, protein turnover and cell cycle. The increased levels of proteins involved in amino‐acid biosynthesis presented a counteracting response to a severe intracellular amino‐acid starvation induced by acetic acid. Deletion of GCN4 and GCN2 encoding key players of general amino‐acid control (GAAC) system caused a higher resistance to acetic acid indicating an involvement of Gcn4p/Gcn2p in the apoptotic signaling. Involvement of the TOR pathway in acetic acid‐induced apoptosis was also reflected by the higher survival rates associated to a terminal deoxynucleotidyl transferase‐mediated dUTP nick end labeling (TUNEL)‐negative phenotype and lower reactive oxygen species levels of Δtor1 cells. In addition, deletion mutants for several downstream mediators of the TOR pathway revealed that apoptotic signaling involves the phosphatases Pph21p and Pph22p but not Sit4p. Altogether, our results indicate that GAAC and TOR pathways (Tor1p) are involved in the signaling of acetic acid‐induced apoptosis.
Identification of secreted proteins regulated by cAMP in glioblastoma cells using glycopeptide capture and label‐free quantification
Authors: Hill Jennifer J. , Moreno Maria J. , Lam Jean C. Y. , Haqqani Arsalan S. , Kelly John F.
Published: January 2009

Exposure of glioblastoma U87MG cells to a cAMP analog leads to a decrease in proliferation, invasion, and angiogenic potential. Here, we apply a label‐free MS‐based approach to identify formerly N‐linked glycopeptides that change in abundance upon cAMP treatment. Over 150 unique glycopeptides in three biological repetitions were quantified, leading to the identification of 14 upregulated proteins and 21 downregulated proteins due to cAMP treatment. Of these, eight have been validated, either through comparison with microarray data or by Western blot. We estimate our ability to identify differentially expressed peptides at greater than 85% in a single biological repetition, while the analysis of multiple biological repetitions lowers the false positive rate to ∼2%. Many of the proteins identified in this study are involved in cell signaling and some, such as Tenascin C, Cathepsin L, Neuroblastoma suppressor of tumorigenicity, and AXL/UFO tyrosine–protein kinase receptor, have been previously shown to be involved in glioblastoma progression. We also identify several semitryptic peptides that increase in abundance upon cAMP treatment, suggesting that cAMP regulates protease activity in these cells. Overall, these results demonstrate the benefits of using a highly specific enrichment method for quantitative proteomic experiments.
Improved protein sequence coverage by on resin deglycosylation and cysteine modification for biomarker discovery
Authors: Kamada Haruhiko , Fugmann Tim , Neri Dario , Roesli Christoph
Published: January 2009

Membrane proteins and secreted factors (soluble proteins or extracellular matrix components) are the targets of most monoclonal antibodies, which are currently in clinical development. These proteins are frequently post‐translationally modified, e.g. by the formation of disulfide bonds or by glycosylation, which complicates their identification using proteomics technologies. Here, we describe a novel methodology for the on resin deglycosylation and cysteine modification of proteins after in vitro, in vivo or ex vivo biotinylation. Biotinylated proteins are captured on streptavidin resin and all subsequent modifications, as well as the proteolytic digestion, which yields peptides for MS analysis, are performed on resin. Using biotinylated bovine fetuin‐A as a test protein, an improvement in sequence coverage from 7.9 to 58.7% could be shown, including the identification of all three glycosylation sites. Furthermore, a complex mixture derived from the ex vivo biotinylation of vascular structures in human kidney with cancer obtained by perfusion after surgical resection revealed almost a doubling of sequence coverage for all checked proteins when analyzed by LC‐MALDI TOF/TOF.
Pharmacokinetics and Pharmacodynamics of Linezolid in Children With Cystic Fibrosis
Authors: Santos Roberto P. , Prestidge Claude B. , Brown Michael E. , Urbancyzk Brenda , Murphey Donald K. , Salvatore Christine M. , Jafri Hasan S. , McCracken George H. , Ahmad Naveed , Sanchez Pablo J. , Siegel Jane D.
Published: January 2009

Alternative antimicrobial regimens are needed for treatment of methicillin‐resistant Staphylococcus aureus (MRSA)‐associated pulmonary exacerbations in children with cystic fibrosis (CF). There are no published pharmacokinetic (PK) and pharmacodynamic (PD) data for linezolid in children with CF.

Objectives

(1) To determine the PK and PD profile of linezolid among children with CF; (2) to characterize the effect of linezolid on MRSA infection; (3) to determine the effect of age and CF transmembrane regulator (CFTR) gene mutations on drug clearance.

Hypotheses

Linezolid clearance is enhanced in children with CF requiring a higher dosage regimen. Age and CFTR gene mutations affect drug clearance.

Methods

This was a retrospective cohort study; medical records of children with MRSA‐associated pulmonary exacerbations treated with linezolid (10 mg/kg/dose IV every 8h) were reviewed. Linezolid peak and trough concentrations in serum were determined by high performance liquid chromatography, PK profiles determined using standard noncompartmental method, and PD indices were evaluated.

Results

10 children (mean ± SD, 10.2 ± 5.5 years) received 14 courses of linezolid at 10 ± 0.4 mg/kg/dose every 8h for 15.4 ± 3.2 days. Seven had homozygous ΔF508 CFTR mutation. Peak and trough linezolid concentrations varied widely (range, 8.4–20.5 and 0.1–11.5 mcg/mL respectively). The PK profile of children <10 years differed significantly from older patients (≥10 years). The PK indices of children with homozygous ΔF508 differed marginally from those with heterozygous CFTR mutations, but there were too few subjects to allow separation of age and CFTR mutations effect. No patient achieved the target PD ratio of AUC/MIC >80. MRSA persisted in sputum or throat culture after treatment with linezolid.

Conclusions

Additional PK and PD data are needed to optimize linezolid therapy in children with cystic fibrosis; it is likely that higher doses will be needed. Pediatr Pulmonol. 2009; 44:148–154. © 2009 Wiley‐Liss, Inc.
Analysis of oligomeric peroxides in synthetic triacetone triperoxide samples by tandem mass spectrometry
Authors: Sigman Michael E. , Clark C. Douglas , Painter Kimberly , Milton Chatham , Simatos Ekaterina , Frisch Jessica L. , McCormick Meghan , Bitter Julie L.
Published: January 2009

Oligomeric peroxides formed in the synthesis of triacetone triperoxide (TATP) have been analyzed by mass spectrometry utilizing both electrospray ionization (ESI) and chemical ionization (CI) to form sodiated adducts (by ESI) and ammonium adducts (by CI and ESI). Tandem mass spectrometry and deuterium isotopic labeling experiments have been used to elucidate the collision‐induced dissociation (CID) mechanisms for the adducts. The CID mechanisms differ for the sodium and ammonium adducts and vary with the size of the oligoperoxide. The sodium adducts of the oligoperoxides, H[OOC(CH3)2]nOOH, do not cyclize under CID, whereas the ammonium adducts of the smaller oligoperoides (n < 6) do form the cyclic peroxides under CID. Larger oligoperoxide adducts with both sodium and ammonium undergo dissociation through cleavage of the backbone under CID to form acyl‐ and hydroperoxy‐terminated oligomers of the general form CH3C(O)[OOC(CH3)2]xOOH, where x is an integer less than the original oligoperoxide degree of oligomerization. The oligoperoxide distribution is shown to vary batch‐to‐batch in the synthesis of TATP and the post‐blast distribution differs slightly from the distribution in the uninitiated material. The oligoperoxides are shown to be decomposed under gentle heating. Copyright © 2009 John Wiley & Sons, Ltd.
Exploiting spatial‐domain simplicity in spectral image analysis
Authors: Keenan Michael R.
Published: January 2009

Full‐spectrum imaging is fast becoming a tool of choice for characterizing heterogeneous materials. Spectral images, which consist of a complete spectrum at each point in a spatial array, can be acquired from a wide variety of surface and microanalytical spectroscopic techniques. It is not uncommon that such spectral image data sets comprise tens of thousands of individual spectra, or more. Given the vast quantities of raw spectral data, factor analysis methods have proved indispensable for extracting the chemical information from these high‐dimensional data sets into a limited number of factors that represent the spectral and spatial characteristics of the sample's composition. It is well known that factor models suffer a ‘rotational ambiguity’, that is, there are an infinite number of factor models that will fit the data equally well. Thus, physically inspired constraints are often employed to derive relatively unique models that make the individual factors more easily interpreted by the practicing analyst. In the present work, we note that many samples undergoing spectral image analysis are ‘simple’ in the sense that only one or a few of the sample's constituents are present at any particular location. When this situation prevails, simplicity in the spatial domain can be exploited to make the resulting factor models more realistic. In particular, orthogonal rotation of the spatial‐domain vectors arising from singular value decomposition (SVD) of the spectral data matrix will be shown to be an effective method for making physically acceptable and easily interpretable estimates of the pure‐component spectra and abundances. Copyright © 2009 John Wiley & Sons, Ltd.
Micro/macrotribological properties of several nano‐scale ionic liquid films on modified silicon wafers
Authors: Zhu Min , Mo Yufei , Zhao Wenjie , Bai Mingwu
Published: January 2009

Three kinds of alkylimidazolium base room temperature ionic liquids (RTILs) were synthesized and their nano‐scale lubricant films were prepared on modified silicon wafers by dip‐coating method. The thicknesses of these films were measured and their relationship between thickness and solution concentration was obtained. Their surface morphologies were observed and contact angles of water on these films were determined. The adhesions and friction coefficients of these films were detected by contact mode AFM. As comparison, their macrotribological properties were evaluated on a UMT‐2MT tribo‐tester. It was found that, in microscale, 1‐hexyl‐3‐methyl‐imidazolium hexafluorophosphate performed the best tribological properties, while in macroscale, its tribological properties were similar with that of 1‐hexyl‐3‐methyl‐imidazolium tetrafluoroborate and better than that of 1‐hexyl‐3‐methyl‐imidazolium adipate. Copyright © 2009 John Wiley & Sons, Ltd.
Determination of the inhibitory effect of decreasing temperature on tribo‐oxidation behaviour of certain steel using EDS analysis
Authors: Wang Hongling , Yan Fengyuan
Published: January 2009

In order to clarify the influence of temperature below freezing point on the tribo‐oxidation of steel–steel friction pairs, tribological behaviour of certain steel from −55 °C to 20 °C was investigated using a ball‐on‐disk tribometer in a thermotank which could provide environment with constant temperature and humidity. The counterbody was a $\varphi$3 mm GCr15 steel ball. The normal load was 0.5 ∼ 2.5 N and the sliding velocity was 0.319 m/s. Worn surface on the steel, wear scar on the steel ball and wear debris were observed and analysed by SEM and EDS. It was found that the friction coefficient presents a sudden increase when the ambient temperature drop from 20 to − 10 °C. This is caused by decrease of relative humidity. The friction coefficient maintains the same value when the temperature change is between − 10 and −55 °C. A drop of temperature from 20 to −55 °C aggravated wear of the steel. Analysis on tribochemical reaction process indicates gradually weakened oxidation of wear debris along with a drop of temperature should account for the aggravation of wear. Furthermore, along with the drop in temperature, the worn surface became rougher and more structure fractures were formed on the friction track, which led to more severe abrasive wear of the steel. Drop of temperature increased abrasive wear but decreased adhesive wear. Copyright © 2008 John Wiley & Sons, Ltd.
Adsorption characteristic of self‐assembled corrole dimers on HOPG
Authors: Miao Xinrui , Gao Aimei , Hiroto Satoru , Shinokubo Hiroshi , Osuka Atsuhiro , Xin Hongliang , Deng Wenli
Published: January 2009

Our study first focus on two types of corrole dimers oxidized and reduced forms on highly oriented pyrolytic graphite (HOPG) surface. Scanning tunneling microscopy (STM), X‐ray photoelectron spectroscopy (XPS) and contact angle measurement (CAM) were used to investigate the self‐assembled monolayers of corrole dimers adsorbed on HOPG surfaces at room temperature in air. XPS and CAM results have confirmed both two molecules adsorbed on an HOPG surface and formed self‐assembled films, and STM experiments found that the corrole dimers adsorbed on HOPG surfaces form similar lobes. The different stable space structure of the oxidized form molecule (OFM) and reduced form molecule (RFM), led to the diversity of the tetramer structural dimensions. The occurrence of molecular aggregations and assembly was controlled by the interactions between molecular–molecular and molecule–substrate. The electrostatic interactions between the molecules control the geometrical sizes and molecule–substrate interactions determine topographical shapes of the self‐assembled corrole dimers on HOPG surface. Copyright © 2009 John Wiley & Sons, Ltd.
A study on effects of TiB2 contents on reactive products and compressive strength of brazed CBN grains
Authors: Ding Wenfeng , Xu Jiuhua , Chen Zhenzhen , Cheng Ze , Fu Yucan
Published: January 2009

The composite fillers were prepared by means of mixing Ag‐Cu‐Ti alloy and TiB2 reinforcing particles. Experimental study was conducted on the chemical reaction and the reactive products at the interface between CBN grains and the composite filler. The compressive strength measurement of brazed CBN grains was performed. Results obtained show that the TiB2particles disperse uniformly in the filler layer. Great influence of TiB2particles is made on the quantity of the reactive products formed on the surface of brazed CBN grains. The destruction of the sharp edges of grains is restrained. Depending on the compact and fine reactive compounds, hard joining is realized for the CBN grain and the filler layer. When the content of TiB2particles in the composite filler is 8 wt%, the thermal damage of the brazed CBN grains are controlled effectively. In this case the compressive strength of the brazed grains reaches 15.3 N, which is as high as that of the original ones. Copyright © 2009 John Wiley & Sons, Ltd.
Digging deep: Exploring college students' knowledge of macroevolutionary time
Authors: Catley Kefyn M. , Novick Laura R.
Published: January 2009

Some ability to comprehend deep time is a prerequisite for understanding macroevolution. This study examines students' knowledge of deep time in the context of seven major historical and evolutionary events (e.g., the age of the Earth, the emergence of life, the appearance of a pre‐modern human, Homo habilis). The subjects were 126 students recruited from psychology, education, and biology classes at two universities. They were assigned to stronger and weaker background groups based on their college‐level biology coursework. Subjects provided startlingly large time ranges for all questions, ranging over several orders of magnitude (e.g., from 1,000 to 600 billion years ago for when most dinosaurs became extinct), coupled with the strong tendency to underestimate how long ago the events occurred. Converting absolute time estimates to relative time estimates allowed subjects' knowledge of the spacing of the events to be examined and also provided a clearer picture of their patterns of over and underestimation. The results of this study suggest that many students are without an effective conceptual framework to make sense of very large time frames. Although there were no consistent differences in the accuracy of students' responses as a function of their biology background, the weaker background students showed greater variability, providing more time estimates at both the low and high extremes. We describe a pedagogical strategy that uses a relative approach presenting major evolutionary events as they unfolded in time and advocate a tool from professional practice to depict events in time and space. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 311–332, 2009
Momentum and kinetic energy: Confusable concepts in secondary school physics
Authors: Bryce T.G.K. , MacMillan K.
Published: January 2009

Researchers and practitioners alike express concerns about the conceptual difficulties associated with the concepts of momentum and kinetic energy currently taught in school physics. This article presents an in‐depth analysis of the treatment given to them in 44 published textbooks written for UK secondary school certificate courses. This is set against some of the more contentious issues apparent in the literature concerned with the underlying physics and pedagogical arguments about how best to help students understand. The research evolved a set of criteria which were used to scrutinize how texts explain ideas and exemplify their applications. Despite the evident merits of many textbooks, the findings suggest that incomplete explanations are surprisingly prevalent, with several fundamental issues likely to be unclear to student readers, particularly those relating to when and where conservation might apply. Confusion exists between these difficult and somewhat overlapping ideas, arguably through the neglect of constructivist considerations. The commonly emphasized mechanistic, number‐crunching approach to the analysis of simple collision problems is judged to be un‐profitable, underlining the more general point that prevailing, accepted content and pedagogy may be the source of many misunderstandings. Implications are discussed and suggestions made for alternative treatments of these deceptively complex topics. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 739–761, 2009
Developing a Tissue Resource to Characterize the Genome of Pancreatic Cancer
Authors: Voidonikolas Georgios , Gingras Marie‐Claude , Hodges Sally , McGuire Amy L. , Chen Changyi , Gibbs Richard A. , Brunicardi F. Charles , Fisher William E.
Published: January 2009

With recent advances in DNA sequencing technology, medicine is entering an era in which a personalized genomic approach to diagnosis and treatment of disease is feasible. However, discovering the role of altered DNA sequences in various disease states will be a challenging task. The genomic approach offers great promise for diseases, such as pancreatic cancer, in which the effect of current diagnostic and treatment modalities is disappointing. To facilitate the characterization of the genome of pancreatic cancer, high‐quality and well‐annotated tissue repositories are needed. This article summarizes the basic principles that guide the creation of such a repository, including sample processing and preservation techniques, sample size and composition, and collection of clinical data elements.
A Hierarchical Ornstein–Uhlenbeck Model for Continuous Repeated Measurement Data
Authors: Oravecz Zita , Tuerlinckx Francis , Vandekerckhove Joachim
Published: January 2009

In this paper, we present a diffusion model for the analysis of continuous-time change in multivariate longitudinal data. The central idea is to model the data from a single person with an Ornstein–Uhlenbeck diffusion process. We extend it hierarchically by allowing the parameters of the diffusion process to vary randomly over different persons. With this approach, both intra and interindividual differences are analyzed simultaneously. Furthermore, the individual difference parameters can be regressed on covariates, thereby providing an explanation of between-person differences. Unstructured and unbalanced data pose no problem for the model to be applied. We demonstrate the method on data from an experience sampling study to investigate changes in the core affect. It can be concluded that different factors from the five factor model of personality are related to features of the trajectories in the core affect space, such as the cross-correlation and variability of the changes.
Limitations of Conduits in Peripheral Nerve Repairs
Authors: Moore Amy M. , Kasukurthi Rahul , Magill Christina K. , Farhadi H. Francis , Borschel Gregory H. , Mackinnon Susan E.
Published: January 2009

Nerve conduits have emerged as alternatives to autologous nerve grafts, but their use in large-diameter nerve deficits remains untested. We report four patients who underwent repair of large-diameter nerves using absorbable nerve conduits and discuss the failed clinical outcomes. The reported cases demonstrate the importance of evaluating the length, diameter, and function of nerves undergoing conduit repair. In large-diameter nerves, the use of conduits should be carefully considered.
Brief report: Direct and indirect relations of risk factors with eating behavior problems in late adolescent females
Authors: Mayer Birgit , Muris Peter , Meesters Cor , Zimmermann‐van Beuningen Ritine
Published: January 2009

This study explored correlations between risk factors and eating behavior problems in late adolescent, non‐clinical females (N = 301). Participants completed questionnaires for assessing eating problems, the closely associated factors of Body Mass Index (BMI) and body dissatisfaction, and a number of other risk variables that are thought to be involved in psychopathology in general, namely insecure attachment, low self‐esteem, and negative affect (i.e., social anxiety and depression). Results indicated that high levels of eating problems were associated with high levels of insecure attachment, social anxiety, and depression, and with low levels of self‐esteem. Further, regression analyses suggested that depression and self‐esteem had a unique, direct relationship with eating problems, whereas insecure attachment and social anxiety only seemed to have indirect relations. The links between these general risk variables and eating behavior problems were independent from the specific eating problem correlates of BMI and body dissatisfaction.
Lyapunov control of a quantum particle in a decaying potential
Authors: Mirrahimi Mazyar
Published: January 2009

A Lyapunov-based approach for the trajectory generation of anN-dimensional Schrödinger equation in whole\mathbb{R}^{N}is proposed. For the case of a quantum particle in anN-dimensional decaying potential the convergence is precisely analyzed. The free system admitting a mixed spectrum, the dispersion through the absolutely continuous part is the main obstacle to ensure such a stabilization result. Whenever, the system is completely initialized in the discrete part of the spectrum, a Lyapunov strategy encoding both the distance with respect to the target state and the penalization of the passage through the continuous part of the spectrum, ensures the approximate stabilization.
Peano type theorem for abstract parabolic equations
Authors: Zubelevich Oleg
Published: January 2009

We consider parabolic problems with non-Lipschitz nonlinearity in the different scales of Banach spaces and prove local-in-time existence theorem.
Fertility assistance program following the Sichuan earthquake in China
Authors: Qin Lang , Luo Shan , Li Xiaohong , Wang Yan , Li Shangwei
Published: January 2009

On May 12, 2008 an earthquake measuring 8.0 on the Richter scale hit Wenchuan in Sichuan province, a mountainous region in western China, and rendered many parents childless. Doctors from the Women's Fertility Program of the Second West China Hospital in Sichuan carried out a post earthquake fertility assistance program in the following 3 months. The program included 3 parts: sociomedical fertility health support; psychological counseling and intervention in reproductive health; and an assisted reproductive technology (ART) service. Couples whose children had died or were disabled in the earthquake were entitled to free fertility counseling and ART, if required. Some women are currently pregnant as a result of the program, which has been successful in helping some surviving couples achieve their reproductive desires.
The Discursive Process of Legalization: Charting Islands of Persuasion in the ICC Case
Authors: Deitelhoff Nicole
Published: January 2009

For many political observers the successful creation of the International Criminal Court (ICC) came as a surprise, as major powers, in particular the United States, had opposed the plans for the ICC. Moreover, the institutional design of the ICC entails enormous sovereignty costs for states but only uncertain benefits. An analysis of the negotiations suggests that the court's successful creation can be attributed to persuasion and discourse within negotiations, that is, a shift in states' interests. The article develops a theoretical model of institutional change that defines the conditions under which persuasion and discourse can affect collective decision making. In particular, this study attempts to show that if (traditionally) weaker actors alter normative and institutional settings of negotiations they can further the chance of persuasion and discourse.
Early Modern Martyrs
Authors: FREEMAN THOMAS S.
Published: January 2009

Inspired by the example of Henry Walpole, an English Jesuit martyr
(who had himself been converted by the example of Edmund
Campion), Dona Luisa de Carvajal journeyed from her native Spain
to preach the gospel in England. Martyrdom eluded her, but she was
repeatedly arrested and died while awaiting repatriation to Spain. Julius
Palmer, a Catholic student at Oxford, converted to Protestantism after
learning the details of the martyrdoms of Ridley and Latimer; he was
burned as a heretic in Reading in 1556. Joyce Lewes, another Protestant
martyred in the same reign, undertook a public and fatal rejection of
Catholicism after being impressed by the willingness of Laurence
Saunders, who had been burned nearby, to die rather than accept
Catholicism. Florimond de Raemond, who would become a prominent
Catholic controversialist, temporarily converted to Protestantism after
witnessing the high profile martyrdom of Anne du Bourg.
From Disobedience to Toleration: William of Ockham and the Medieval Discourse on Fraternal Correction
Authors: SHOGIMEN TAKASHI
Published: January 2009

In order to tackle the problem of ecclesiastical heresy, late medieval theologians elaborated on the idea of fraternal correction. Alexander of Hales laid the foundation of the standard theological discourse, which was developed by Thomas Aquinas. In applying this concept to the problem of papal heresy, William of Ockham questioned and reversed the hierarchical assumptions and premises in the traditional discourse. Drawing on his ethical theory of invincible ignorance, he also provided a moral basis for an inferior's dissent from ecclesiastical authority. Ockham's emphasis on the inalienable obligation of conscience in defence of ecclesiastical disobedience shows a striking similarity to some of John Locke's ideas on religious toleration.
ON MARKOV-SWITCHING ARMA PROCESSES—STATIONARITY, EXISTENCE OF MOMENTS, AND GEOMETRIC ERGODICITY
Authors: Stelzer Robert
Published: January 2009

The probabilistic properties of ℝd-valued Markov-switching autoregressive moving average (ARMA) processes with a general state space parameter chain are analyzed. Stationarity and ergodicity conditions are given, and an easy-to-check general sufficient stationarity condition based on a tailor-made norm is introduced. Moreover, it is shown that causality of all individual regimes is neither a necessary nor a sufficient criterion for strict negativity of the associated Lyapunov exponent.

Finiteness of moments is also considered and geometric ergodicity and strong mixing are proven. The easily verifiable sufficient stationarity condition is extended to ensure these properties.
MODELING MULTIPLE REGIMES IN FINANCIAL VOLATILITY WITH A FLEXIBLE COEFFICIENT GARCH(1,1) MODEL
Authors: Medeiros Marcelo C. , Veiga Alvaro
Published: January 2009

In this paper a flexible multiple regime GARCH(1,1)-type model is developed to describe the sign and size asymmetries and intermittent dynamics in financial volatility. The results of the paper are important to other nonlinear GARCH models. The proposed model nests some of the previous specifications found in the literature and has the following advantages. First, contrary to most of the previous models, more than two limiting regimes are possible, and the number of regimes is determined by a simple sequence of tests that circumvents identification problems that are usually found in nonlinear time series models. The second advantage is that the novel stationarity restriction on the parameters is relatively weak, thereby allowing for rich dynamics. It is shown that the model may have explosive regimes but can still be strictly stationary and ergodic. A simulation experiment shows that the proposed model can generate series with high kurtosis and low first-order autocorrelation of the squared observations and exhibit the so-called Taylor effect, even with Gaussian errors. Estimation of the parameters is addressed, and the asymptotic properties of the quasi-maximum likelihood estimator are derived under weak conditions. A Monte-Carlo experiment is designed to evaluate the finite-sample properties of the sequence of tests. Empirical examples are also considered.
ON THE LACK OF POWER OF OMNIBUS SPECIFICATION TESTS
Authors: Escanciano J. Carlos
Published: January 2009

Designed to have power against all alternatives, omnibus consistent tests are the primary econometric tools for testing the correct specification of parametric conditional means when there is no information about the possible alternative. The main purpose of this paper is to show that, contrary to what is generally believed, omnibus specification tests only have substantial local power against alternatives in a finite-dimensional space (usually unknown to the researcher). We call such a space theprincipal space. We characterize and estimate the principal space for Cramér–von Mises tests. These results are some of the by-products of a detailed theoretical power analysis carried out in the paper. This investigation focuses on the class of the so-called integrated consistent tests under possibly heteroskedastic time series. A Monte Carlo experiment examines the finite-sample properties of tests and estimators of preferred alternatives. Finally, an application of our theory to test the martingale difference hypothesis of some exchange rates provides new information on the rejection of omnibus tests and illustrates our findings.
COMPUTATIONALLY EFFICIENT RECURSIONS FOR TOP-ORDER INVARIANT POLYNOMIALS WITH APPLICATIONS
Authors: Hillier Grant , Kan Raymond , Wang Xiaolu
Published: January 2009

The top-order zonal polynomials Ck(A), and top-order invariant polynomials Ck1,…,kr (A1, …, Ar) in which each of the partitions of ki, i = 1, …, r, has only one part, occur frequently in multivariate distribution theory, and econometrics — see, for example, Phillips (1980, Econometrica 48, 861–878; 1984, Journal of Econometrics 26, 387–398; 1985, International Economic Review 26, 21–36; 1986, Econometrica 54, 881–896), Hillier (1985, Econometric Theory 1, 53–72; 2001, Econometric Theory 17, 1–28), Hillier and Satchell (1986, Econometric Theory 2, 66–74), and Smith (1989, Journal of Multivariate Analysis 31, 244–257; 1993, Australian Journal of Statistics 35, 271–282). However, even with the recursive algorithms of Ruben (1962, Annals of Mathematical Statistics 33, 542–570) and Chikuse (1987, Econometric Theory 3, 195–207), numerical evaluation of these invariant polynomials is extremely time consuming. As a result, the value of invariant polynomials has been largely confined to analytic work on distribution theory. In this paper we present new, very much more efficient, algorithms for computing both the top-order zonal and invariant polynomials. These results should make the theoretical results involving these functions much more valuable for direct practical study. We demonstrate the value of our results by providing fast and accurate algorithms for computing the moments of a ratio of quadratic forms in normal random variables.
A foodborne outbreak ofCryptosporidium hominisinfection
Authors: ETHELBERG S. , LISBY M. , VESTERGAARD L. S. , ENEMARK H. L. , OLSEN K. E. P. , STENSVOLD C. R. , NIELSEN H. V. , PORSBO L. J. , PLESNER A.-M. , MØLBAK K.
Published: January 2009

Foodborne outbreaks of cryptosporidiosis are uncommon. In Denmark human cases are generally infrequently diagnosed. In 2005 an outbreak of diarrhoea affected company employees near Copenhagen. In all 99 employees were reported ill; 13 were positive forCryptosporidium hominisinfection. Two analytical epidemiological studies were performed; an initial case-control study followed by a cohort study using an electronic questionnaire. Disease was associated with eating from the canteen salad bar on one, possibly two, specific weekdays [relative risk 4·1, 95% confidence interval (CI) 2·1–8·3]. Three separate salad bar ingredients were found to be likely sources: peeled whole carrots served in a bowl of water, grated carrots, and red peppers (in multivariate analysis, whole carrots: OR 2·1, 95% CI 1·1–4·0; grated carrots: OR 2·1, 95% CI 1·2–3·9; peppers: OR 3·3, 95% CI 1·7–6·6). We speculate that a person excreting the parasite may have contaminated the salad buffet.
Coherent flow structures in a depth‐limited flow over a gravel surface: The role of near‐bed turbulence and influence of Reynolds number
Authors: Hardy Richard J. , Best James L. , Lane Stuart N. , Carbonneau Patrice E.
Published: January 2009

In gravel bed rivers, the microtopography of the bed exerts a significant effect on the generation of turbulent flow structures. Although field and laboratory measurements have indicated that flows over gravel beds contain coherent macroturbulent flow structures, the origin of these phenomena, and their relationship to the ensemble of individual roughness elements forming the bed, is not quantitatively well understood. Here we report upon a flume experiment in which flow over a gravel surface is quantified through the application of digital particle imaging velocimetry, which allows study of the downstream and vertical components of velocity over the entire flow field. The results indicate that as the Reynolds number increases (1) the visual distinctiveness of the coherent flow structures becomes more defined, (2) the upstream slope of the structures increases, and (3) the turbulence intensity of the structures increases. Analysis of the mean velocity components, the turbulence intensity, and the flow structure using quadrant analysis demonstrates that these large‐scale turbulent structures originate from flow interactions with the bed topography. Detection of the dominant temporal length scales through wavelet analysis enables calculation of mean separation zone lengths associated with the gravel roughness through standard scaling laws. The calculated separation zone lengths demonstrate that wake flapping is a dominant mechanism in the production of large‐scale coherent flow structures in gravel bed rivers. Thus, we show that coherent flow structures over gravels owe their origin to bed‐generated turbulence and that large‐scale outer layer structures are the result of flow‐topography interactions in the near‐bed region associated with wake flapping.