bluuebunny/crossref_metadata_2025_split huggingface dataset:
A neurochemical signature of visual recovery after extrastriate cortical damage in the adult cat
Authors: Huxlin Krystel R. , Williams Jennifer M. , Price Tracy 
Published: February 2008

AbstractIn adult cats, damage to the extrastriate visual cortex on the banks of the lateral suprasylvian (LS) sulcus causes severe deficits in motion perception that can recover as a result of intensive direction discrimination training. The fact that recovery is restricted to trained visual field locations suggests that the neural circuitry of early visual cortical areas, with their tighter retinotopy, may play an important role in attaining perceptual improvements after damage to higher level visual cortex. The present study tests this hypothesis by comparing the manner in which excitatory and inhibitory components of the supragranular circuitry in an early visual cortical area (area 18) are affected by LS lesions and postlesion training. First, the proportion of LS‐projecting pyramidal cells as well as calbindin‐ and parvalbumin‐positive interneurons expressing each of the four AMPA receptor subunits was estimated in layers II and III of area 18 in intact animals. The degree to which LS lesions and visual retraining altered these expression patterns was then assessed. Both LS‐projecting pyramidal cells and inhibitory interneurons exhibited long‐term, differential reductions in the expression of glutamate receptor (GluR)1, ‐2, ‐2/3, and ‐4 following LS lesions. Intensive visual training post lesion restored normal AMPAR subunit expression in all three cell‐types examined. Furthermore, for LS‐projecting and calbindin‐positive neurons, this restoration occurred only in portions of the ipsi‐lesional area 18 representing trained visual field locations. This supports our hypothesis that stimulation of early visual cortical areas—in this case, area 18—by training is an important factor in restoring visual perception after permanent damage to LS cortex. J. Comp. Neurol. 508:45–61, 2008. © 2008 Wiley‐Liss, Inc.
Complexity of a modelling exercise: A discussion of the role of computer simulation in complex system science
Authors: Boschetti Fabio , McDonald David , Gray Randall 
Published: February 2008

AbstractShifting the emphasis from a model to a modeling task, which involves both a computer model and a modeler, we ask what makes a problem complex. We propose that a modeling task can be seen as a set of questions‐and‐answers, nested at multiple levels. The role of the modeler then lies in posing the questions and choosing the best procedure to answer them, while the role of the model lies in answering the questions, via algorithmic, thus logically simple, procedures. Within this framework, complexity is broadly related to the number of question‐answer levels involved in the process and the nature of the questions posed. Addressing this complexity depends crucially on the ingenuity and creativity of the modeler. This may lead to a view of complexity, which is no more observer‐independent, but rather accounts for both historical and cultural development, that is the context of the problem at hand. © 2008 Wiley Periodicals, Inc. Complexity, 2008.
An enhanced TCP for upward vertical handoff in integrated WLAN and cellular networks
Authors: Lee Jong Hyup , Lee Su Kyoung , Song Joo Seok 
Published: February 2008

AbstractThe integration of wireless local area networks (WLANs) and third generation (3G) cellular networks has been recently a subject of great interest, mainly aimed at augmenting cellular networks with high‐rate data services by WLANs in hotspots. The complementary characteristics of 3G cellular networks and 802.11 WLANs are expected to offer the best of both technologies. On the other hand, the drastically different characteristics of both networks could be a serious obstacle to providing seamless mobility in the integrated WLAN and cellular networks. In particular, mobile users suffer from a drastic decrease in data rate after a vertical handoff from a WLAN to a 3G cellular network. However, current TCP congestion control cannot adapt to the change in the data rate after the vertical handoff, resulting in significant throughput degradation. Thus, we propose a novel TCP scheme to enhance the throughput when a vertical handoff occurs from a WLAN to a cellular network. For the proposed scheme, the throughput performance is investigated via analytic modeling and simulation. Copyright © 2008 John Wiley & Sons, Ltd.
Signalling enhancement on multilevel turbo codes
Authors: Bayat Oguz , Shafai Bahram , Salehi Masoud , Ucan Osman N. , Osman Onur 
Published: February 2008

AbstractThe design of multilevel turbo codes usingM‐PSK is optimized to achieve a low bit error rate (BER). Unequal error protection is employed via group set partitioning in multi‐stage decoding to minimize the error propagation and BER. Simulation results are performed under Gaussian and Rayleigh fading channels to depict the superiority of the new scheme. Copyright © 2008 John Wiley & Sons, Ltd.
Centrifugal migration of mesenchymal cells in embryonic lung
Authors: Shan Lin , Subramaniam Meera , Emanuel Rodica L. , Degan Simone , Johnston Pamela , Tefft Denise , Warburton David , Sunday Mary E. 
Published: February 2008

AbstractMurine lung development begins at embryonic day (E) 9.5. Normal lung structure and function depend on the patterns of localization of differentiated cells. Pulmonary mesenchymal cell lineages have been relatively unexplored. Importantly, there has been no prior evidence of clonality of any lung cells. Herein we use a definitive genetic approach to demonstrate a common origin for proximal and distal pulmonary mesenchymal cells. A retroviral library with 3,400 unique inserts was microinjected into the airway lumen of E11.5 lung buds. After 7–11 days of culture, buds were stained for placental alkaline phosphatase (PLAP). Most PLAP+ cells are peribronchial smooth muscle cells, initially localized laterally near the hilum, then migrating down airways to the subpleural region. Laser‐capture microdissection and polymerase chain reaction confirm the clonal identities of PLAP+ cells proximally and distally. Our observation of this fundamental process during lung development opens new avenues for investigation of maladaptive mesenchymal responses in lung diseases. Developmental Dynamics 237:750–757, 2008. © 2008 Wiley‐Liss, Inc.
Novel tool to suppress cell proliferation in vivo demonstrates that myocardial and coronary vascular growth represent distinct developmental programs
Authors: Lavine Kory J. , Schmid Gregory J. , Smith Craig S. , Ornitz David M. 
Published: February 2008

AbstractCell proliferation, differentiation, and vascular growth are coordinated processes that are essential for embryonic development, tissue repair, and disease pathogenesis. Of interest, whether these critical processes are dependent upon each other has not been thoroughly explored. We have generated mice that conditionally express the cell cycle inhibitor p27Kip1, following Cre‐mediated recombination, as a tool to separate tissue proliferation from other cellular processes. Using the embryonic heart as a model, we show that myocardial proliferation and coronary development are genetically separable processes. Forced expression of p27, in both a wild‐type and in a genetically sensitized background, resulted in ventricular hypoplasia without having any substantial effects on coronary development. We further demonstrate that Hedgehog signaling, which is essential for coronary vascular growth, does not control myocardial proliferation. Together, these studies strongly suggest that myocardial cell proliferation and coronary development are genetically separable programs exemplifying one of the many potential uses of this genetic tool. Developmental Dynamics 237:713–724, 2008. © 2008 Wiley‐Liss, Inc.
Primary cilia sensitize endothelial cells for fluid shear stress
Authors: Hierck Beerend P. , Van der Heiden Kim , Alkemade Fanneke E. , Van de Pas Simone , Van Thienen Johannes V. , Groenendijk Bianca C.W. , Bax Wilhelmina H. , Van der Laarse Arnoud , DeRuiter Marco C. , Horrevoets Anton J.G. , Poelmann Robert E. 
Published: February 2008

AbstractPrimary cilia are mechanosensors for fluid shear stress, and are involved in a number of syndromes and congenital anomalies. We identified endothelial cilia in areas of low shear stress in the embryonic heart. The objective of the present study was to demonstrate the role of primary cilia in mechanosensing. Ciliated embryonic endothelial cells were cultured from the heart, and non‐ciliated cells from the arteries. Non‐ciliated cells that were subjected to fluid shear stress showed significantly less induction of the shear marker Krüppel‐Like Factor‐2, as compared to ciliated cells. In addition, ciliated cells from which the cilia were chemically removed show a similar decrease in flow response. This shows that primary cilia sensitize endothelial cells for fluid shear stress. In addition, we targeted and stabilized the connection of the cilium to the cytoplasm by treatment with Colchicine and Taxol/Paclitaxel, respectively, and show that microtubular integrity is essential to sense shear stress. Developmental Dynamics 237:725–735, 2008. © 2008 Wiley‐Liss, Inc.
Alternative splicing and expression analysis of bovine DNA methyltransferase 1
Authors: Russell D. Fischer , Betts D. H. 
Published: February 2008

AbstractMethylation of specific CG residues in the mammalian genome results in tissue‐specific patterns of gene expression, which are critical for cell differentiation. Embryos that fail to establish and maintain proper DNA methylation patterns show severe developmental abnormalities as is the case of DNA methyltransferase 1 (Dnmt1) ‐deficient embryos. Dnmt1 is the main maintenance methyltransferase in the mouse and its expression is regulated by a splicing mechanism that dictates the expression of stage‐specific isoforms. Little is known about Dnmt1 expression in the cow and isoforms of Dnmt1 are yet unknown in this species. Here we demonstrate that the previously described bovine Dnmt1 transcript is ubiquitously expressed in embryos and fetal tissue. In addition, we report the identification of a splice variant of the bovine Dnmt1, which shows a ubiquitous expression pattern. This new transcript was detected using 5′RACE and genomic mapping and its expression pattern was shown to be consistent with a tissue‐specific mode of regulation. Furthermore, our analysis shows that the expression of an oocyte‐specific isoform of Dnmt1 is unlikely to occur in cattle. The newly reported isoform of Dnmt1 was demonstrated to be, similarly to Dnmt1a, polyadenylated and if translated possess the functional domains necessary for maintenance and de novo methyltransferase activity. Developmental Dynamics 237:1051–1059, 2008. © 2008 Wiley‐Liss, Inc.
Transcriptional activity and developmental expression of liver X receptor (lxr) in Zebrafish
Authors: Archer Amena , Lauter Gilbert , Hauptmann Giselbert , Mode Agneta , Gustafsson Jan‐Åke 
Published: February 2008

AbstractMammalian liver‐X‐receptors (LXRs) are transcription factors activated by oxysterols. They play an essential role in lipid and glucose metabolism. We have cloned the open reading frame of zebrafish lxr and describe its genomic organization. Zebrafish lxr encodes a 50‐kDa protein with high sequence similarity to mammalian LXRα. In transfection assays, the encoded protein showed transcriptional activity in response to LXR‐ligands. Treatment of adult zebrafish with the synthetic LXR ligand, GW3965, induced expression of genes involved in hepatic cholesterol and lipid pathways. Using qPCR and in situ hybridization, we found ubiquitous expression of lxr mRNA during the first 24 hr of development, followed by more restricted expression, particularly to the liver at 3dpf and the liver and intestine at 4dpf. In adult fish, all examined organs expressed lxr. In addition to a metabolic role of lxr, the temporal expression pattern suggests a developmental role in, e.g., the liver and CNS. Developmental Dynamics 237:1090–1098, 2008. © 2008 Wiley‐Liss, Inc.
Inactivation of zebrafish mrf4 leads to myofibril misalignment and motor axon growth disorganization
Authors: Wang Yun‐Hsin , Li Chun‐Kai , Lee Gang‐Hui , Tsay Huey‐Jen , Tsai Huai‐Jen , Chen Yau‐Hung 
Published: February 2008

AbstractMrf4 is a basic helix‐loop‐helix (bHLH) transcription factor associated with myogenesis. Two mrf4 transcripts, mrf4_tv1 and mrf4_tv2, were identified in zebrafish generated by alternative splicing. To study their biological functions, we separately injected the Mrf4‐morpholinos, including MO1 (mrf4_tv1:mrf4_tv2 knockdown), MO2+MO3 (mrf4_tv1:mrf4_tv2 knockdown), MO3 (mrf4_tv1 knockdown), and MO4 (mrf4_tv2 knockdown), into zebrafish embryos to observe mrf4 gene knockdown phenotypes. No phenotypic abnormalities were observed following injection with 0.5 ng of MO1 but those injected with 4.5, 9, or 13.5 ng displayed curved‐body phenotypes, such as indistinct somite boundaries, and a lack of uniformly sized cell blocks. Similar results were also observed in the (MO2+MO3)‐, MO3‐, and MO4‐injected groups. To further investigate the molecular mechanisms that lead to curved‐body phenotypes, we stained embryos with α‐bungrotoxin and specific monoclonal antibodies F59, Znp1, and Zn5 to detect morphological changes in acetyl‐choline receptor (AChR) clusters, muscle fibers, common path of the primary neurons, and secondary neurons axonal projections, respectively. Our results show that the muscle fibers of mrf4_(tv1:tv2)‐morphant aligned disorderly and lost their integrity and attachment, while the defects became milder in either mrf4_tv1‐morphant or mrf4_tv2‐morphant. On the other hand, reduced axonal projections and AChR clusters were found in both mrf4_tv2‐morphant and mrf4_(tv1:tv2)‐morphant but distributed normally in the mrf4_tv1‐morphant. We conclude that Mrf4_tv2 is involved in alignment of muscle fibers, and Mrf4_tv1 might have cooperative function with Mrf4_tv2 in muscle fiber alignment, without affecting the muscle‐nerve connection. Developmental Dynamics 237:1043–1050, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis and Characterization of a Ladder‐Like Coordination Polymer Composed of Trimanganese Clusters Formed and Linked by Isophthalato Ligands
Authors: Ma Cheng‐Bing , Chen Chang‐Neng , Liu Qiu‐Tian , Liao Dai‐Zheng , Li Li‐Cun 
Published: February 2008

AbstractA new isophthalatomanganese(II) coordination polymer, [Mn3(ip)2(Hip)2(bipy)2]n·2.5nH2O [H2ip = isophthalic acid, bipy = 2,2′‐bipyridine], has been obtained directly by heating to reflux a weakly acidic solution containing bipy, Mn(OAc)2·4H2O, and H2ip. The polymer was characterized by single‐crystal X‐ray diffraction and magnetic measurements. The complex contains rare isophthalato‐bridged trimanganese cluster building units further linked by isophthalato ligands in a newly observed binding mode, forming a one‐dimensional, ladder‐like chain network. The magnetic interactions within the complex were quantitatively evaluated by using a combination of a trimeric model and a mean molecular field approximation model. The complex was shown to be antiferromagnetic like other discrete trimanganese clusters with a structurally similar core.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Facile Synthesis of Large meso‐Pentafluorophenyl‐Substituted Expanded Porphyrins (Eur. J. Org. Chem. 8/2008)
Authors: Tanaka Yasuo , Shin Ji‐Young , Osuka Atsuhiro 
Published: February 2008

AbstractThe cover picture shows the crystal structures and colors of meso‐pentafluorophenyl‐substituted expanded porphyrins. [18]Porphyrin, [26]hexaphyrin, [36]octaphyrin, [44]decaphyrin, [52]dodecaphyrin, [62]tetradecaphyrin, [72]hexadecaphyrin, and [80]octadecaphyrin were synthesized and characterized. As indicated, the absorption bands of these expanded porphyrins are redshifted as their size increases, and [80]octadecaphyrin shows its absorption maximum at 953 nm. Their solutions exhibit various colors, reflecting the macrocyclic conjugation like a rainbow. Details are discussed in the article by A. Osuka et al. on p. 1341 ff.
Development of a simple and highly sensitive mutation screening system by enzyme mismatch cleavage with optimized conditions for standard laboratories
Authors: Tsuji Takanori , Niida Yo 
Published: February 2008

AbstractEfficient screening of unknown DNA variations is one of the substantive matters of molecular biology even today. Historically, SSCP and heteroduplex analysis (HA) are the most commonly used methods for detecting DNA variations everywhere in the world because of their simplicity. However, the sensitivity of these methods is not satisfactory for screening purpose. Recently, several new PCR‐based mutation screening methods have been developed, but most of them require special instruments and adjustment of conditions for each DNA sequence to attain the maximum sensitivity, eventually becoming as inconvenient as old methods. Enzyme mismatch cleavage (EMC) is potentially an ideal screening method. With high‐performance nucleases and once experimental conditions are optimized, it requires only conventional staff and conditions remain the same for each PCR product. In this study we tested four commercially available endonucleases for EMC and optimized the electrophoresis and developing conditions. We prepared 25 known DNA variations consisting of 18 single base substitutions (8 transitions and 10 transversions, including all possible sets of mismatches) and 7 small deletions or insertions. The combination of CEL nuclease, 12% PAGE and rapid silver staining can detect all types of mutations and achieved 100% sensitivity.
Single‐index and portfolio models for forecasting value‐at‐risk thresholds
Authors: McAleer Michael , da Veiga Bernardo 
Published: February 2008

AbstractThe variance of a portfolio can be forecast using a single index model or the covariance matrix of the portfolio. Using univariate and multivariate conditional volatility models, this paper evaluates the performance of the single index and portfolio models in forecasting value‐at‐risk (VaR) thresholds of a portfolio. Likelihood ratio tests of unconditional coverage, independence and conditional coverage of the VaR forecasts suggest that the single‐index model leads to excessive and often serially dependent violations, while the portfolio model leads to too few violations. The single‐index model also leads to lower daily Basel Accord capital charges. The univariate models which display correct conditional coverage lead to higher capital charges than models which lead to too many violations. Overall, the Basel Accord penalties appear to be too lenient and favour models which have too many violations. Copyright © 2008 John Wiley & Sons, Ltd.
Forecasting for the LCD monitor market
Authors: Lo Shin‐Lian , Wang Fu‐Kwun , Lin James T. 
Published: February 2008

AbstractThe TFT‐LCD (thin‐film transistor–liquid crystal display) industry is one of the key global industries with products that have high clock speed. In this research, the LCD monitor market is considered for an empirical study on hierarchical forecasting (HF). The proposed HF methodology consists of five steps. First, the three hierarchical levels of the LCD monitor market are identified. Second, several exogenously driven factors that significantly affect the demand for LCD monitors are identified at each level of product hierarchy. Third, the three forecasting techniques—regression analysis, transfer function, and simultaneous equations model—are combined to forecast future demand at each hierarchical level. Fourth, various forecasting approaches and disaggregating proportion methods are adopted to obtain consistent demand forecasts at each hierarchical level. Finally, the forecast errors with different forecasting approaches are assessed in order to determine the best forecasting level and the best forecasting approach. The findings show that the best forecast results can be obtained by using the middle‐out forecasting approach. These results could guide LCD manufacturers and brand owners on ways to forecast future market demands. Copyright 2008 John Wiley & Sons, Ltd.
The occurrence and research potential of microfossils in inorganic archaeological materials
Authors: Quinn Patrick Sean 
Published: February 2008

AbstractThe microscopic remains of organisms, or “microfossils,” can occur within or attached to a range of different inorganic archaeological materials. Because of their small size, these inconspicuous phenomena can be easily overlooked. However, as this paper illustrates, the detailed biological and palaeontological analysis of microfossils in such contexts may be an important source of archaeological data. By critically reviewing a range of specialized cross‐disciplinary analyses, it is shown how microfossils can be used to provenance inorganic artifacts, reconstruct aspects of their manufacturing technology, and infer their function. © 2008 Wiley Periodicals, Inc.
Palaeoeskimo site burial by solifluction: Periglacial geoarchaeology of the tayara site (KbFk‐7), Qikirtaq Island, Nunavik (Canada)
Authors: Todisco Dominique , Bhiry Najat 
Published: February 2008

AbstractThe geoarchaeological study of the Palaeoeskimo Tayara site on Qikirtaq Island (Nunavik) has led to a better understanding of archaeological site formation in the arctic periglacial environment. The surrounding geomorphology (extra‐site) is characterized by fine‐grained, low plastic and leached postglacial glaciomarine sediments that have been reworked by sheet‐like solifluction. This process buried the northern part of the Tayara site with mean annual rates between 1.68 and 2.86 cm/yr over approximately 350 years (1330–980 yr B.P.). The physicochemical and mineralogical properties of the frost‐susceptible glaciomarine sediments may explain their susceptibility to solifluction. This process was probably enhanced by longer thawing periods or warmer/moister summer months that induced active layer thickening or rapid soil thawing. The dates we obtained in the downstream valley show that solifluction occurred during short warm periods in the Late Holocene between ca. 1500 and 1000 yr B.P., after 1000 yr B.P. (or after 500 yr B.P.) and recently (90–60 yr B.P.). Our data provide insights on the site factors and climate factors that govern site burial by solifluction. Solifluction promoted the preservation of the three superposed archaeological levels in the Tayara site; however, the waterlogging of the site related to solifluction also likely caused the subsequent abandonment of the site by the Palaeoeskimo people. © 2008 Wiley Periodicals, Inc.
Estimation of significance thresholds for genomewide association scans
Authors: Dudbridge Frank , Gusnanto Arief 
Published: February 2008

AbstractThe question of what significance threshold is appropriate for genomewide association studies is somewhat unresolved. Previous theoretical suggestions have yet to be validated in practice, whereas permutation testing does not resolve a discrepancy between the genomewide multiplicity of the experiment and the subset of markers actually tested. We used genotypes from the Wellcome Trust Case‐Control Consortium to estimate a genomewide significance threshold for the UK Caucasian population. We subsampled the genotypes at increasing densities, using permutation to estimate the nominal P‐value for 5% family‐wise error. By extrapolating to infinite density, we estimated the genomewide significance threshold to be about 7.2 × 10−8. To reduce the computation time, we considered Patterson's eigenvalue estimator of the effective number of tests, but found it to be an order of magnitude too low for multiplicity correction. However, by fitting a Beta distribution to the minimum P‐value from permutation replicates, we showed that the effective number is a useful heuristic and suggest that its estimation in this context is an open problem. We conclude that permutation is still needed to obtain genomewide significance thresholds, but with subsampling, extrapolation and estimation of an effective number of tests, the threshold can be standardized for all studies of the same population. Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.