bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forecasting performance of extreme‐value volatility estimators
Authors: Vipul  , Jacob Joshy 
Published: September 2007

AbstractThis study evaluates the forecasting performance of extreme‐value volatility estimators for the equity‐based Nifty Index using two‐scale realized volatility. This benchmark mitigates the effect of microstructure noise in the realized volatility. Extreme‐value estimates with relatively simple forecasting methods provide substantially better short‐term and long‐term forecasts, compared to historical volatility. The higher efficiency of extreme‐value estimators is primarily responsible for this improvement. The extent of possible improvement in forecasts is likely to be economically significant for applications like options pricing. By including extremevalue estimators, the forecasting performance of generalized autoregressive conditional heteroscedasticity (GARCH) can also be improved. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27: 1085–1105, 2007
A new look at hedging with derivatives: Will firms reduce market risk exposure?
Authors: Bali Turan G. , Hume Susan R. , Martell Terrence F. 
Published: September 2007

AbstractThis study examines derivatives use of foreign exchange, interest rate, and commodities risk by nonfinancial firms across multiple industries, using data from 1995 to 2001. This work considers the interaction of a firm's risk exposures, derivatives use, and real operations simultaneously, and considers how these factors change over time using a consistent database. Hedging with derivatives is only signi.cantly related to commodity risk exposure during most years of the study, and to a more limited degree to interest rate exposure. Further, a strong correlation was found between risk exposures for some years using a new technique, suggesting that univariate modeling is not always appropriate. The implications are that hedging with derivatives is not always important to a firm's rate of return and is linked to other nonfinancial and economic factors. © 2007 Wiley Periodicals, Inc. Jrl Fut Mark 27: 1053–1083, 2007
Inferential testing for linkage with GENEHUNTER‐MODSCORE: The impact of the pedigree structure on the null distribution of multipoint MOD scores
Authors: Mattheisen Manuel , Dietter Johannes , Knapp Michael , Baur Max P. , Strauch Konstantin 
Published: September 2007

AbstractThe asymptotic distribution of [MOD] scores under the null hypothesis of no linkage is only known for affected sib pairs and other types of affected relative pairs. We have extended the GENEHUNTER‐MODSCORE program to allow for simulations under the null hypothesis of no linkage to determine the empirical significance of MOD‐score results in general situations. We performed simulations with families of different size (one million replicates of 500 families per simulation setting) to thoroughly investigate the impact of the pedigree size on the null distribution of multipoint MOD scores. It is shown that the distribution is dependent on the size and structure of the pedigrees under study. By performing simulations in the context of MOD‐score analysis, our new tool efficiently explores the linkage data in a comprehensive way and also provides a valid method to inferentially test for linkage. Genet. Epidemiol. 2007. © 2007 Wiley‐Liss, Inc.
A principal components regression approach to multilocus genetic association studies
Authors: Wang Kai , Abbott Diana 
Published: September 2007

AbstractWith the rapid development of modern genotyping technology, it is becoming commonplace to genotype densely spaced genetic markers such as single nucleotide polymorphisms (SNPs) along the genome. This development has inspired a strong interest in using multiple markers located in the target region for the detection of association. We introduce a principal components (PCs) regression method for candidate gene association studies where multiple SNPs from the candidate region tend to be correlated. In this approach, the total variance in the original genotype scores is decomposed into parts that correspond to uncorrelated PCs. The PCs with the largest variances are then used as regressors in a multiple regression. Simulation studies suggest that this approach can have higher power than some popular methods. An application to CHI3L2 gene expression data confirms a significant association between CHI3L2 gene expression level and SNPs from this gene that has been previously reported by others. Genet. Epidemiol. 2008. © 2007 Wiley‐Liss, Inc.
Astrocyte membrane responses and potassium accumulation during neuronal activity
Authors: Meeks Julian P. , Mennerick Steven 
Published: September 2007

AbstractOlder studies suggest that astrocytes act as potassium electrodes and depolarize with the potassium efflux accompanying neuronal activity. Newer studies suggest that astrocytes depolarize in response to neuronal glutamate release and the activity of electrogenic glial glutamate transporters, thus casting doubt on the fidelity with which astrocytes might sense extracellular potassium rises. Any K+‐induced astrocyte depolarization might reflect a spatial buffering effect of astrocytes during neuronal activity. For these reasons, we studied stimulus‐evoked currents in hippocampal CA1 astrocytes. Hippocampal astrocytes exhibited stimulus‐evoked transient glutamate transporter currents and slower Ba2+‐sensitive inward rectifier potassium (Kir) currents. In whole‐cell astrocyte recordings, Ba2+ blocked a very weakly rectifying component of the astrocyte membrane conductance. The slow stimulus‐elicited current, like measurements from K+‐sensitive electrodes under the same conditions, predicted small bulk [K+]o increases (<0.5 mM) following the termination of short‐stimulus trains. These currents indicate the potential for astrocyte spatial K+ buffering. However, Ba2+ did not significantly affect resting [K+]o or the [K+]o rises detected by the K+‐sensitive electrode. To test whether local K+ rises may be significantly higher than those detected by glial recordings or by K+ electrodes, we assayed EPSCs and fiber volleys, two measures very sensitive to K+ increases. We found that Ba2+ had little effect on neuronal axonal or synaptic function during short‐stimulus trains, indicating that Kirs do not influence local [K+]o rises enough, under these conditions to affect synaptic transmission. In conclusion, our results indicate that hippocampal astrocytes are faithful sensors of [K+]o rises, but we find little evidence for physiologically relevant spatial K+ buffering during brief bursts of presynaptic activity. © 2007 Wiley‐Liss, Inc.
Memory for familiar environments learned in the remote past: fMRI studies of healthy people and an amnesic person with extensive bilateral hippocampal lesions
Authors: Rosenbaum R. Shayna , Winocur Gordon , Grady Cheryl L. , Ziegler Marilyne , Moscovitch Morris 
Published: September 2007

AbstractPreserved remote spatial memory in amnesic people with bilateral hippocampal damage, including the well‐studied case K.C., challenges spatial theories, which assume that the hippocampus is needed to support all allocentric spatial representations, old or new. It remains possible, however, that residual hippocampal tissue is functional and contributes to successful performance. Here, we examine brain activity with fMRI during the retrieval of spatial information in K.C. and in healthy controls using landmark and route stimuli from a premorbidly familiar neighborhood that K.C. can navigate normally. In all participants, activity was found in the parahippocampal cortex, but not in the hippocampus itself, during all navigational tasks on which K.C. performs well, even though part of his hippocampus remains viable. The opposite pattern was observed on a house recognition task, which is inconsequential to navigation, and on which K.C. performed poorly. On that task, K.C. recruited the right hippocampus presumably because even “familiar” houses were treated as novel by him, whereas controls recruited occipitotemporal cortex, including parahippocampal cortex. The distinction between recent and remote memory, therefore, may apply as much to spatial theories of hippocampal function as it does to theories emphasizing the role of the hippocampus in other types of explicit memory. © 2007 Wiley‐Liss, Inc.
An examination of fatigue striations in human dentin: In vitro and in vivo
Authors: Bajaj D. , Sundaram N. , Arola D. 
Published: September 2007

AbstractAlthough striations are often used in evaluating fatigue crack growth in engineering materials, they have not been used in studying the mechanics of fracture in hard tissues. The primary objective of this study was to evaluate the striations resulting from fatigue crack growth in the dentin of human teeth. Compact tension (CT) specimens obtained from the coronal dentin of molars from young (17 ≤ age ≤ 37 years) and senior (age ≥ 50 years) patients were subjected to cyclic Mode I loads. Striations evident on the fracture surfaces were examined using a scanning electron microscope (SEM) and contact profilometer. Fatigue crack growth striations that developed in vivo were also examined on fracture surfaces of restored molars. A power spectrum analysis of surface profiles from the CT specimens showed that the striation spacing ranged from 50 to 170 μm. The average spacing in the dentin of seniors (130 ± 23 μm) was significantly larger (p < 0.001) than that in young dentin (88 ± 13 μm). Fatigue striations in the restored teeth exhibited features that were consistent with those that developed in vitro and a spacing ranging from 59 to 95 μm. Unlike metals, the striations in dentin developed after a period of cyclic loading that ranged from 1 × 103 to 1 × 105 cycles. A quantitative evaluation of the striation spacing using the Bates‐Clark equation suggested that cyclic crack growth within the restored teeth occurred at a stress intensity range near 0.7 MPa·m0.5, and a stress range of ∼12 MPa. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Calcium phosphate‐based coatings on titanium and its alloys
Authors: Narayanan R. , Seshadri S. K. , Kwon T. Y. , Kim K. H. 
Published: September 2007

AbstractUse of titanium as biomaterial is possible because of its very favorable biocompatibility with living tissue. Titanium implants having calcium phosphate coatings on their surface show good fixation to the bone. This review covers briefly the requirements of typical biomaterials and narrowly focuses on the works on titanium. Calcium phosphate ceramics for use in implants are introduced and various methods of producing calcium phosphate coating on titanium substrates are elaborated. Advantages and disadvantages of each type of coating from the view point of process simplicity, cost‐effectiveness, stability of the coatings, coating integration with the bone, cell behavior, and so forth are highlighted. Taking into account all these factors, the efficient method(s) of producing these coatings are indicated finally. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Human tooth culture: A study model for reparative dentinogenesis and direct pulp capping materials biocompatibility
Authors: Téclès Odile , Laurent Patrick , Aubut Virginie , About Imad 
Published: September 2007

AbstractIn a previous work, based on an in vitro entire tooth culture model of human immature third molars, we demonstrated that perivascular progenitor cells can proliferate and migrate to the injury site after pulp exposure. In this work, we investigated the differentiation of cells after direct capping with biomaterials classically used in restorative dentistry. Histological staining after direct pulp capping with Calcium Hydroxide XR® or MTA revealed early and progressive mineralized foci formation containing BrdU‐labeled sequestered cells. The molecular characterization of the matrix and the sequestered cells by immunohistochemistry (Collagene type I, Dentin sialoprotein, and Nestin) clearly demonstrates that these areas share common characteristics of the mineralized matrix of reparative dentin formed by odontoblast‐like cells. This reproduces some features of the pulp responses after applying these materials in vivo and demonstrates that the entire tooth culture model reproduces a part of the early steps of dentin regeneration in vivo. Its future development may be useful in studying the effects of biomaterials on this process. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
The human micro‐vascular endothelial cells in vitro interaction with atomic‐nitrogen‐doped diamond‐like carbon thin films
Authors: Okpalugo T. I. T. , Ogwu A. A. , Okpalugo A. C. , McCullough R. W. , Ahmed W. 
Published: September 2007

AbstractThis paper reports the initial response of atomic nitrogen doped diamond like carbon (DLC) to endothelial cells in vitro. The introduction of nitrogen atoms/molecules to the diamond like carbon structures leads to an atomic structural change favorable to the attachment of human micro‐vascular endothelial cells. Whilst the semi‐conductivity induced by nitrogen in DLC is thought to play a part, the increase in the non‐bonded N atoms and N2 molecules in the atomic doped species (with the exclusion of the charged species) seems to contribute to the improved attachment of human microvascular endothelial cells. The increased endothelial attachment is associated with a lower work function and slightly higher water contact angle in the atomic doped films, where the heavy charged particles are excluded. The films used in the study were synthesized by the RF PECVD technique followed by post deposition doping with nitrogen, and afterwards the films were characterized by XPS, Raman spectroscopy, SIMS and Kelvin probe. The water contact angles were measured, and the counts of the adherent endothelial cells on the samples were carried out. This study is relevant and contributory to improving biocompatibility of surgical implants and prostheses. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
High‐resolution water window X‐ray imaging of in vivo cells and their products using LiF crystal detectors
Authors: Bonfigli Francesca , Faenov Anatoly , Flora Francesco , Francucci Massimo , Gaudio Pasqualino , Lai Antonia , Martellucci Sergio , Montereali Rosa Maria , Pikuz Tania , Reale Lucia , Richetta Maria , Vincenti Maria Aurora , Baldacchini Giuseppe 
Published: September 2007

AbstractHigh contrast imaging of in vivo Chlorella sorokiniana cells with submicron spatial resolution was obtained with a contact water window X‐ray microscopy technique using a point‐like, laser‐plasma produced, water‐window X‐ray radiation source, and LiF crystals as detectors. This novel type of X‐ray imaging detectors is based on photoluminescence of stable electronic point defects, characterized by high intrinsic resolution. The fluorescence images obtained on LiF crystals exposed in single‐shot experiments demonstrate the high sensitivity and dynamic range of this new detector. The powerful performances of LiF crystals allowed us to detect the exudates of Chlorella cells in their living medium and their spatial distribution in situ, without any special sample preparation. Microsc. Res. Tech., 2008. © 2007 Wiley‐Liss, Inc.
Comparative modeling of marsupial MHC class I molecules identifies structural polymorphisms affecting functional motifs
Authors: Daly Kerry , Bret Church W. , Nicholas Kevin , Williamson Peter 
Published: September 2007

AbstractMajor histocompatibility complex (MHC) class I molecules are transmembrane glycoproteins that present antigenic peptides to CD8+ T cells and are subsequently important for the initiation of an immune response. In this study novel MHC class I sequences from the tammar wallaby (Macropus eugenii) have been characterized. Analysis and comparative modeling of these and existing marsupial molecules reveals potential functional polymorphisms within peptide‐binding grooves, MHC assembly motifs and the T cell receptor recognition interface. In addition, we show that a previously identified marsupial‐specific insertion is within a region, which is known as a putative NK cell receptor (Ly49A) binding site in the mouse, suggesting that this site may be functionally active in marsupials. Further, the analysis highlighted differences in structural and sequence based grouping of marsupial MHC class I molecules. J. Exp. Zool. 307A:611–624, 2007. © 2007 Wiley‐Liss, Inc.
Osteoinductive effect of bone bank allografts on human osteoblasts in culture
Authors: de la Piedra Concepción , Vicario Carlos , de Acuña Lucrecia Rodríguez , García‐Moreno Carmen , Traba Maria Luisa , Arlandis Santiago , Marco Fernando , López‐Durán Luis 
Published: September 2007

AbstractIncorporation of a human bone allograft requires osteoclast activity and growth of recipient osteoblasts. The aim of this work was to study the effects produced by autoclavated and −80°C frozen bone allografts on osteoblast proliferation and synthesis of interleukin 6 (IL6), activator of bone resorption, aminoterminal propeptide of procollagen I (PINP), marker of bone matrix formation, and osteoprotegerin (OPG), inhibitor of osteoclast activity and differentiation. Allografts were obtained from human femoral heads. Human osteoblasts were cultured in the presence (problem group) or in the absence (control group) of allografts during 15 days. Allografts produced a decrease in osteoblast proliferation in the first week of the experiment, and an increase in IL6 mRNA, both at 3 h and 2 days, and an increase in the IL6 released to the culture medium the second day of the experiment. We found a decrease in OPG released to the culture on the 2nd and fourth days. These results suggest an increase in bone resorption and a decrease in bone formation in the first week of the experiment. In the second week, allografts produced an increase in osteoblast proliferation and PINP release to the culture medium, indicating an increase in bone formation; an increase in OPG released to the culture medium, which would indicate a decrease in bone resorption; and a decrease in IL6, indicating a decrease in bone resorption stimulation. These results demonstrate that autoclavated and −80°C frozen bone allografts produce in bone environmemt changes that regulate their own incorporation to the recipient bone. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:200–207, 2008
Interface membrane fibroblasts around aseptically loosened endoprostheses express MMP‐13
Authors: Wagner Susanne , Gollwitzer Hans , Wernicke Dirk , Langer Rupert , Siebenrock Klaus A. , Hofstetter Willy 
Published: September 2007

AbstractThe objective of this article was to assess whether matrix metalloproteinase‐13 (MMP‐13) is produced by cells of the peri‐implant interface tissues and to further characterize these cells. Tissue specimens were collected from the bone–prosthesis interface at the time of revision surgery of clinically loosened hip and knee arthroplasties (n = 27). Synovial tissues from osteoarthritic patients and young patients with mild joint deformity were used as controls (n = 6). Tissue samples were fixed in 4% PFA, decalcified with EDTA, and embedded in paraffin. Sections (4 µm) were stained with hematoxylin/eosin and for the osteoclastic marker enzyme tartrate resistant acid phosphatase. Monocytes/macrophages were characterized with a monoclonal antibody against CD68 and mRNAs encoding MMP‐13 and α1 collagen I (COL1A1) were detected by in situ hybridization. Cells expressing transcripts encoding MMP‐13 were found in 70% of the interface tissues. These cells colocalized with a cell population expressing COL1A1 mRNA, and were fibroblastic in appearance. MMP‐13 expressing cells were found in the close vicinity of osteoclasts and multinuclear giant cells. No signals for transcripts encoding MMP‐13 were detected in multinuclear giant cells or in osteoclasts. Control tissues were negative for transcripts encoding MMP‐13 mRNA. Fibroblasts of the interface from aseptically loosened endoprostheses selectively express MMP‐13. By the expression and the release of MMP‐13, these fibroblastic cells may contribute to the local degradation of the extracellular matrix and to bone resorption. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:143–152, 2008
Clonal T‐cell response against autologous pleomorphic malignant fibrous histiocytoma antigen presented by retrieved HLA‐A*0206
Authors: Kimura Shigeharu , Kozakai Yuriko , Kawaguchi Satoshi , Tsukahara Tomohide , Ida Kazunori , Murase Masaki , Matsumura Tadaki , Kaya Mitunori , Torigoe Toshihiko , Wada Takuro , Sato Noriyuki , Yamashita Toshihiko 
Published: September 2007

AbstractTowards the goal of identifying tumor‐rejection antigens on eradicated tumors in bone and soft tissue sarcomas, we evaluated the immune response against antigens presented by lost HLA class I molecules. Tumor specimens and peripheral blood samples were obtained from a 70‐year‐old woman with pleomorphic malignant fibrous histiocytoma. Over 1‐year culture, a tumor cell line (MFH2004) was established. A B‐cell line infected with Epstein–Barr virus (B2004‐EBV) was developed from the blood samples. HLA genotypes of B2004‐EBVcells were A*0206/2402, B*4006/4601, and C*0102/0801, whereas MFH2004 cells were defective for A*0206, B*4006, and C*0102. Loss of HLA‐A2 expression was also proved immunohistochemically in the primary tumor tissues. Lost HLA‐A2 in MFH2004 cells was retrieved by transfection of HLA‐A*0206 cDNA to develop MFH2004‐A2. Attempts to induce CTLs by mixed culture with autologous T cells and MFH2004 cells resulted in failure. In contrast, those with MFH2004‐A2 induced CTL clones CTL2004‐c6 and CTL2004‐c17. These CTL clones specifically killed MFH2004‐A2 but not MFH2004 or B2004‐EBV in an HLA‐A2‐restricted manner. These findings suggest that CTL2004‐c6 and CTL2004‐c17 recognize autologous tumor‐rejection antigens presented by HLA‐A*0206, which may have been expressed by tumor cells that had been eradicated by the host's immunosurveillance system. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:271–278, 2008
Inhibition effect of {surfactant–substrate} aggregation on the rate of oxidation of reducing sugars by alkaline hexacyanoferrate(III)
Authors: Shukla Ratna , Upadhyay Santosh K. 
Published: September 2007

AbstractThe effect of cationic (cetyltrimethylammonium bromide, CTAB), anionic (sodium lauryl sulfate, NaLS), and nonionic (Brij‐35) surfactants on the rate of oxidation of some reducing sugars (xylose, glucose, and fructose) by alkaline hexacyanoferrate(III) has been studied in the temperature range from 35 to 50°C. The rate of oxidation is strongly inhibited in the presence of surfactant. The inhibition effect of surfactant on the rate of reaction has been observed below critical micelle concentration (CMC) of CTAB. In case of NaLS and Brij‐35, the inhibition effect was above CMC, at which the surfactant abruptly associates to form micelle. The kinetic data have been accounted for by the combination of surfactant molecule(s) with a substrate molecule in case of CTAB and distribution of substrate into micellar and aqueous pseudophase in case of NaLS and Brij‐35. The binding parameters (binding constants, partition coefficients, and free‐energy transfer from water to micelle) in case of NaLS and Brij‐35 have been evaluated with the help of Menger and Portnoy model reported for micellar inhibition. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 595–604, 2007