bluuebunny/crossref_metadata_2025_split huggingface dataset:
A MLPG(LBIE) numerical method for solving 2D incompressible and nearly incompressible elastostatic problems
Authors: Vavourakis V. , Polyzos D. 
Published: December 2006

AbstractA new meshless local Petrov–Galerkin (MLPG) method, based on local boundary integral equation (LBIE) considerations, is proposed here for the solution of 2D, incompressible and nearly incompressible elastostatic problems. The method utilizes, for its meshless implementation, nodal points spread over the analysed domain and employs the moving least squares (MLS) approximation for the interpolation of the interior and boundary variables. On the local and global boundaries, traction vectors are treated in a way so that no derivatives of the utilized MLS shape functions are required. Both displacement and hydrostatic pressure, at all the considered nodal points, are evaluated with the aid of local integral representations valid for incompressible and nearly incompressible solids. Since displacements and stresses are treated as independed variables, the boundary conditions are imposed directly without any problem via the integrals defined on the global boundary of the analysed body. Singular and hypersingular integrals are evaluated directly with high accuracy through advanced integration techniques. Three numerical examples illustrate the proposed methodology and demonstrates its accuracy. Copyright © 2006 John Wiley & Sons, Ltd.
From Cloudy to Transparent: Chain Rearrangement in Hydrogen‐Bonded Layer‐by‐Layer Assembled Films
Authors: Yang Shuguang , Zhang Yongjun , Zhang Xiaoyan , Guan Ying , Xu Jian , Zhang Xiaoli 
Published: December 2006

AbstractThe cloudiness of hydrogen‐bonded LBL films assembled from polyvinylpyrrolidone (PVPON) and poly(acrylic acid) (PAA) is studied in detail by two approaches: spectroscopy (Fabry–Pérot fringes) and microscopy (AFM). Fabrication parameters such as temperature, molecular weight, pH value, and rinsing time, have notable influences on film cloudiness. The buildup of the PVPON/PAA film is a two‐stage process of adsorption and chain rearrangement. Generally, adsorption is fast, while chain rearrangement is slow. The fast adsorption process traps defects, whereas the relatively slow chain‐rearrangement process can not heal the defects in time; therefore, the number of defects continuously increases as LBL assembly proceeds, and a cloudy, heterogeneous film is produced. However, the as‐prepared cloudy films become transparent and homogeneous on subsequent annealing in acidic water. UV/Vis spectroscopy and fluid AFM were applied to monitor this transition ex situ and in situ, respectively. It is found that increasing the annealing temperature accelerates the transition from cloudy to transparent, and the transition of the film made from higher molecular weight polymer is slower.
Heparan sulfate Ndst1 gene function variably regulates multiple signaling pathways during mouse development
Authors: Pallerla Srinivas R. , Pan Yi , Zhang Xin , Esko Jeffrey D. , Grobe Kay 
Published: December 2006

AbstractDisruption of heparan sulfate (HS) synthesis in vertebrate development causes malformations that are composites of those caused by mutations of multiple HS binding growth factors and morphogens. We previously reported severe developmental defects of the forebrain and the skull in mutant mice bearing a targeted disruption of the heparan sulfate‐generating enzyme GlcNAc N‐deacetylase/GlcN N‐sulfotransferase 1 (Ndst1). Here, we further characterize the molecular mechanisms leading to frontonasal dysplasia in Ndst1 mutant embryos and describe additional malformations, including impaired spinal and cranial neural tube fusion and skeletal abnormalities. Of the numerous proteins that bind HS, we show that impaired fibroblast growth factor, Hedgehog, and Wnt function may contribute to some of these phenotypes. Our findings, therefore, suggest that defects in HS synthesis may contribute to multifactor types of congenital developmental defects in humans, including neural tube defects. Developmental Dynamics 236:556–563, 2007. © 2006 Wiley‐Liss, Inc.
Use, option and externality values: are contingent valuation studies in health care mis‐specified?
Authors: Smith Richard D. 
Published: December 2006

AbstractA general population sample of Australian respondents completed a contingent valuation (CV) survey that asked them to value six scenarios. These varied according to whether the scenario was seeking to elicit: (i) use value; (ii) externality value; (iii) option value; or (iv) a combination. Results indicate that useplusexternality and/or option value was significantly greater than use value alone. As CV studies in health (care) overwhelmingly focus on use value alone – often implicitly through study design rather than explicitly – this raises the possibility of mis‐specification in CV research in health (care). The implications for CV in health (care) are considered. Copyright © 2006 John Wiley & Sons, Ltd.
Roles of learning and motivation in preference behavior: Mediation by entorhinal cortex, dorsal and ventral hippocampus
Authors: Stouffer Eric M. , White Norman M. 
Published: December 2006

AbstractIn the latent cue preference (LCP) task, water‐deprived rats alternately drink a salt solution in one distinctive compartment of a conditioned cue preference (CCP) apparatus and water in the other compartment over 8 days (training trials). They are then given a choice between the two compartments with no solutions present (preference test). Previous findings showed that this training procedure results in two parallel forms of learning: conditioning to water‐paired cues (a water‐CCP) and latent learning of an association between salt and salt‐paired compartment cues (a salt‐LCP). Experiment 1 examined these two types of learning in isolation. Results showed that expression of the salt‐LCP required salt deprivation during testing, but expression of the water‐CCP did not require a deprivation state during testing. Other results showed that salt‐LCP learning itself involves two distinct components: (1) the latent association among neutral cues in the salt‐paired compartment, and (2) motivational information about salt deprivation during testing. Previous findings also demonstrated roles for the dorsal hippocampus (DH), ventral hippocampus (VH), and entorhinal cortex (EC) in salt‐LCP learning. Experiment 2 examined the involvement of these structures during acquisition or expression of salt‐LCP learning. Rats with cannulas aimed at DH, VH, or EC were given infusions of muscimol, either before exposure to the salt‐paired, but not the water‐paired, compartment during training or before the preference test. Inactivation of the DH or EC impaired both acquisition and expression of the association between salt and salt‐paired compartment cues, while inactivation of the VH disrupted the influence of motivational information about salt deprivation required to express the salt‐LCP. These results suggest unique roles for the EC‐DH circuit and VH in salt‐LCP learning, as well as a functional dissociation between the DH and VH. © 2006 Wiley‐Liss, Inc.
Expression of embryonic tau protein isoforms persist during adult neurogenesis in the hippocampus
Authors: Bullmann Torsten , de Silva Rohan , Holzer Max , Mori Hiroshi , Arendt Thomas 
Published: December 2006

AbstractTau is a microtubule‐associated protein with a developmentally regulated expression of multiple isoforms. The neonatal isoform is devoid of two amino terminal inserts and contains only three instead of four microtubule‐binding repeats (0N/3R‐τ). We investigated the temporal expression pattern of 0N‐τ and 3R‐τ in the rat hippocampus. After the decline of 0N‐ and 3R‐τ immunoreactivity during the postnatal development both isoforms remain highly expressed in a few cells residing beneath the granule cell layer. Coexpression of the polysialylated neuronal cell adhesion molecule, doublecortin, and incorporated bromodeoxyuridine showed that these cells are proliferating progenitor cells. In contrast mature granule cells express the adult tau protein isoform containing one aminoterminal insert domain (1N‐τ). Therefore a shift in tau isoform expression takes place during adult neurogenesis, which might be related to migration, differentiation, and integration in the granule cell layer. A model for studying shifts in tau isoform expression in a defined subset of neurons might help to understand the etiology of tauopathies, when isoform composition is crucial for neurodegeneration, as in Pick's disease or FTDP‐17. © 2006 Wiley‐Liss, Inc.
On the use of partial probability weighted moments in the analysis of hydrological extremes
Authors: Moisello Ugo 
Published: January 2007

AbstractThe use of partial probability weighted moments (PPWM) for estimating hydrological extremes is compared to that of probability weighted moments (PWM). Firstly, estimates from at‐site data are considered. Two Monte Carlo analyses, conducted using continuous and empirical parent distributions (of peak discharge and daily rainfall annual maxima) and applying four different distributions (Gumbel, Fréchet, GEV and generalized Pareto), show that the estimates obtained from PPWMs are better than those obtained from PWMs if the parent distribution is unknown, as happens in practice. Secondly, the use of partial L‐moments (obtained from PPWMs) as diagnostic tools is considered. The theoretical partial L‐diagrams are compared with the experimental data. Five different distributions (exponential, Pareto, Gumbel, GEV and generalized Pareto) and 297 samples of peak discharge annual maxima are considered. Finally, the use of PPWMs with regional data is investigated. Three different kinds of regional analyses are considered. The first kind is the regression of quantile estimates on basin area. The study is conducted applying the GEV distribution to peak discharge annual maxima. The regressions obtained with PPWMs are slightly better than those obtained with PWMs. The second kind of regional analysis is the parametric one, of which four different models are considered. The congruence between local and regional estimates is examined, using peak discharge annual maxima. The congruence degree is sometimes higher for PPWMs, sometimes for PWMs. The third kind of regional analysis uses the index flood method. The study, conducted applying the GEV distribution to synthetic data from a lognormal joint distribution, shows that better estimates are obtained sometimes from PPWMs, sometimes from PWMs. All the results seem to indicate that using PPWMs can constitute a valid tool, provided that the influence of ouliers, of course higher with censored samples, is kept under control. Copyright © 2007 John Wiley & Sons, Ltd.
Comparison of structure, strength and cytocompatibility of a fibrin matrix supplemented either with tranexamic acid or aprotinin
Authors: Furst Walter , Banerjee Asmita , Redl Heinz 
Published: December 2006

AbstractFibrin sealants are used as hemostats, sealants, tissue adhesives, and as matrix for substances/cells in a number of surgical and tissue engineering procedures. Main characteristics of fibrin are high tensile strength, adhesive strength, biocompatibility, and resorption. A major adverse event would be premature fibrin lysis and recurrent bleeding. This must be prevented by fibrinolysis inhibitors. The most common fibrinolysis inhibitors used are aprotinin and tranexamic acid (t‐AMCA). Comparison of commercially available fibrin sealants utilizing aprotinin or t‐AMCA revealed a lower sealing efficacy in an in vivo lung resection model for a t‐AMCA containing product. Therefore, we compared the influence of t‐AMCA and aprotinin on structure, mechanical properties, and cytocompatibility of a fibrin matrix. In our experiments, we found that substitution of aprotinin with t‐AMCA reduced the tensile strength and formation of fibrin fibers and affected viability of a fibroblast cell‐line. In conclusion, t‐AMCA negatively affects physical and biological properties of fibrin relevant for clinical application as well as tissue regeneration. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006
Human hepatoblast phenotype maintained by hyaluronan hydrogels
Authors: Turner William S. , Schmelzer Eva , McClelland Randall , Wauthier Eliane , Chen Weiliam , Reid Lola M. 
Published: December 2006

AbstractHuman hepatoblasts and hepatic stem cells, pluripotent hepatic progenitors that give rise to hepatocytes and biliary cells, were isolated from fetal livers and found to express hyaluronan receptors (CD44) in both the freshly isolated cells and after culture. This implicates an in vivo connection to hyaluronan (HA), an embryonic matrix component, as a candidate 3‐dimensional (3‐D) scaffold for hepatic progenitor cell expansion and/or differentiation. To assess HAs as scaffolds, hepatoblasts and hepatic stem cells were seeded into HA hydrogels with a serum‐free, hormonally defined medium tailored for expansion of hepatic progenitors. Cell aggregates formed within the HA hydrogels and remained viable, proliferative, and demonstrated a stable phenotype intermediate between that of hepatic stem cells and hepatoblasts throughout more than 4 weeks of culturing, with little evidence of lineage restriction towards either hepatocytic or biliary pathways. The phenotype consisted of stable co‐expression of both hepatocytic and biliary markers such as biliary‐specific cytokeratin, CK19, low levels of expression of albumin, and urea synthesis. HA hydrogels are ideal as 3‐D scaffolds for pluripotent hepatic progenitors and should be useful for generating cells to be used in bioartificial livers or tissue engineered liver grafts. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006.
Mechanical and biocompatible influences of chitosan fiber and gelatin on calcium phosphate cement
Authors: Pan Zhaohui , Jiang Pingping , Fan Qingyu , Ma Baoan , Cai Heping 
Published: December 2006

AbstractCalcium phosphate cement (CPC) is a widely used bone substitute in the clinic; however, the low strength of CPC limits its utilization. In this study, we investigated mechanical influences of chitosan fiber combined with gelatin on CPC, and examined the biocompatibility of the new composite with rat bone marrow stromal cells. Compared to the fiber impregnated in phosphate buffered saline (80.5 MPa), our study showed that tensile strength of chitosan fiber increased 106 and 114% with the impregnation of gelatin at the mass fraction 5 and 10%, although this increase was not statistically significant. It was demonstrated by Fourier transform infrared spectroscopy that the characteristic absorption bands of chitosan were changed with the addition of gelatin. The optimal flexural strength enhancement was obtained when CPC was reinforced with fiber at volume fraction of 30% and gelatin at mass fraction of 5% (maximum: 12.31 MPa). The fiber morphology was more compact when the chitosan fibers impregnated with gelatin at mass fraction of 5 or 10% than chitosan alone. The fracture analysis showed that the new CPC–chitosan fiber–gelatin composite presented many remnants of CPC adhered to fibers. Short minimum essential medium extract test showed no cell growth inhibition after the addition of the new composite. Rat bone marrow stromal cells retain the ability to spread and grow on the composite. Our studies demonstrated that the flexural strength is greatly increased by using CPC incorporated with proper ratio of CF and gelatin. More over, the new composite demonstrated biocompatibility in vitro. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006.
BMP‐7 loaded microspheres as a new delivery system for the cultivation of human chondrocytes in a collagen type‐I gel
Authors: Gavénis Karsten , Klee Doris , Pereira‐Paz Rui M. , Walter Matthias von , Mollenhauer Jürgen , Schneider Ulrich , Schmidt‐Rohlfing Bernhard 
Published: December 2006

AbstractIn recent years, interest in chondrocyte cultures for transplantation has gained increasing attention. We investigated the use of PGLA microspheres as a new delivery system for BMP‐7 and the effects on human chondrocytes cultivated in a 3D collagen gel culture. In an in vitro study, human chondrocytes obtained from osteoarthritic knee joints were released, transferred into a collagen type‐I gel, and cultivated up to 14 days. In the treatment group PGLA microspheres loaded with human recombinant BMP‐7 protein were added to the matrix. After the cultivation period, histological and immunohistochemical investigations were performed. In addition, the aggrecan core protein and type‐II collagen mRNA concentrations were measured by real‐time PCR. Histological staining for proteoglycan and collagen type‐II protein and quantification via digital image processing revealed a significantly higher content in the samples cultivated with BMP‐7 loaded microspheres in comparison to the control samples. Moreover, the collagen gel scaffold was partially remodeled by the chondrocytes and replaced by newly synthesized extracellular matrix. Cellular proliferation as well as apoptosis were low. In conclusion, we consider the PGLA microsphere system to be a functional device for the delivery of growth factors during the cultivation of articular chondrocytes leading to an increased content of type‐II collagen and proteoglycan in the extracellular matrix. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2006.
Preparing for “diastole”: Advanced training opportunities for academic hospitalists
Authors: Arora Vineet , Fang Margaret C. , Kripalani Sunil , Amin Alpesh N. 
Published: December 2006

AbstractAcademic hospital medicine can be described as comprising periods of “systole,” during which hospitalists provide clinical care, and periods of “diastole,” the portion of a hospitalist's time spent in nonclinical activities. Far from being a period of relaxation, diastole is an active component of a hospitalist's work, the time devoted to the pursuit of career advancement. This period is a critical opportunity for career development in terms of medical research, education, quality improvement, or administration. An appropriate balance of systole and diastole may potentially prevent burnout and allow hospitalists opportunities to focus on academic advancement. Although an increasing number of residency graduates opt for a career in academic hospital medicine, few are prepared for the period of diastole. This article describes several career options in academic hospital medicine, specifically, opportunities in education, research, quality improvement, and administrative opportunities. By informing future hospitalists about the career opportunities within academic hospital medicine possible through managing their diastolic time, we hope that future generations of trainees will be better prepared to enter this field. Journal of Hospital Medicine 2006;1:368–377. © 2006 Society of Hospital Medicine.
Tendons and ligaments are anatomically distinct but overlap in molecular and morphological features—a comparative study in an ovine model
Authors: Rumian Adam P. , Wallace Andrew L. , Birch Helen L. 
Published: January 2007

AbstractTendons and ligaments are similar in composition but differ in function. Simple anatomical definitions do not reflect the fact individual tendons and ligaments have unique properties due to their adaptation to a specific role. The patellar tendon is a structure of particular clinical interest. A null hypothesis was declared stating that the patellar tendon is not significantly different in terms of matrix composition and collagen fibril diameter to other tendons. The lateral and medial collateral ligaments (LCL, MCL), anterior and posterior cruciate ligaments (ACL, PCL), together with the long digital extensor, superficial digital extensor, and patellar tendons (LDET, SDFT, PT) were harvested from three cadaveric ovine hindlimbs. The extracellular matrix was assessed in terms of water, collagen, and total sulphated glycosaminoglycan (GAG) content. The organization of the collagen component was determined by an ultrastructural analysis of collagen fibril diameter distributions, together with values for the collagen fibril index (CFI) and mass‐average diameter (MAD). There were significant differences between ligaments and tendons. The PT had a bimodal collagen fibril diameter distribution with CFI 72.9%, MAD 202 nm, water content 53.1%, GAG content 2.3 µg/mg, and collagen content 73.7%, which was not significantly different from the other tendons. The results of this study support the null hypothesis suggesting that the patellar tendon is similar to other tendons and demonstrate that tendons have different characteristics to ligaments. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:458–464, 2007
The three paths: Meeting leadership challenges in China and India
Authors: Hedrick‐Wong Yuwa 
Published: December 2006

AbstractBusinesses in Asia, notably in China and India, have traditionally been endowed with entrepreneurial energy. Where they have often fallen short is in efficiently structured, professionally run, and inspirational corporate leadership. An analysis of the three routes through which individuals in China and India become business leaders will go a long way toward resolving this disconnect.
Getting to the source: Four perspectives on leadership
Authors: Day David V. , O'Connor Patricia M. G. 
Published: December 2006

AbstractIn the midst of all the innovative business strategies being deployed to respond to globalization, one fundamental aspect often remains unexamined: how leadership is accomplished. What are the most prevalent forms of organizational leadership and their relative strengths and weaknesses, and how can a leader reflect on the type of leadership found in his or her organization and whether that approach is the most appropriate for attaining the organization's strategic goals?
On a class of holomorphic functions representable by Carleman formulas in the disk from their values on the arc of the circle
Authors: Aizenberg Lev , Vidras Alekos 
Published: December 2006

AbstractLet D be a unit disk andM be an open arc of the unit circle whose Lebesgue measure satisfies 0 < l (M) < 2π. Our first result characterizes the restriction of the holomorphic functions f ∈ ℋ︁(D), which are in the Hardy class ℋ︁1 near the arcM and are denoted by 𝒩 ℋ︁1M (𝒟), to the open arcM. This result is a direct consequence of the complete description of the space of holomorphic functions in the unit disk which are represented by the Carleman formulas on the open arc M.As an application of the above characterization, we present an extension theorem for a function f ∈ L 1(M) from any symmetric sub‐arc L ⊂ M of the unit circle, such that $ \bar L $ ⊂ M, to a function f ∈ 𝒩 ℋ︁1L (𝒟). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The maximal operator in Lebesgue spaces with variable exponent near 1
Authors: Hästö Peter A. 
Published: December 2006

AbstractThis article contains results about the boundedness of the Hardy–Littlewood maximal operator in variable exponent Lebesgue spaces. We study the situation where the exponent approaches one in some parts of the domain. We show that the boundedness depends on how fast the exponent approaches one and give nearoptimal bounds for necessary and sufficient growths. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)