bluuebunny/crossref_metadata_2025_split huggingface dataset:
Controlled and Living Polymerizations Induced with Rhodium Catalysts. A Review
Authors: Sedláček Jan , Vohlídal Jiří 
Published: October 2003

In the last fifteen years, a large variety of specialty polymers of diverse chemical structure and functionality have been synthesized with the rhodium-based catalysts. The high tolerance to the reaction medium and functional groups of monomers, as well as ability to control various structure features of the polymer formed are typical properties of these catalysts. In addition, some rhodium catalysts can be anchored to inorganic or organic supports or dissolved in ionic liquids to form heterophase polymerization systems, which opens the way to pure, well-defined polymers free of the catalyst residues, as well as to recycling rhodium catalysts. This review provides a survey on the polymerization reactions induced with rhodium-based catalysts, in which one or more structure attributes of the polymer formed are subject to control. The structure attributes considered are (i) sequential arrangement of monomeric units along polymer chains; (ii) head-tail isomerism of polymer molecules; (iii) configurational structure of polymer molecules; (iv) conformation of polymer molecules; and (v) molecular weight and molecular-weight distribution of the polymer formed. A review with 188 references.
Triple Loop Networks with Minimal Transmission Delay
Authors: Jia Xingde , Su Weidong 
Published: October 2003

A multiloop network is a Cayley digraph of the additive group ℤm of integers modulo m generated by a set A of k ≥ 2 "steps". Because of their application to the computer network design, multiloop networks have been studied extensively. Given an integer d ≥ 2 and a real number r > 1, let m(d,3) be the maximum size of a triple loop network with transmission delay (diameter) less than or equal to d, and let m*(r,3) be the maximum size of a triple loop network with average transmission delay less than or equal to r. In this paper, the following lower bounds are proved: [Formula: see text] which improve earlier lower bounds by Jia and Aguiló, Fiol and Garcia.
Image and Video Compression: A Review
Authors: Podilchuk Christine I. , Safranek Robert J. 
Published: October 2003

The area of image and video compression has made tremendous progress over the last several decades. The successes in image compression are due to advances and better understanding of waveform coding methods which take advantage of the signal statistics, perceptual methods which take advantage of psychovisual properties of the human visual system (HVS) and object-based models especially for very low bit rate work. Recent years have produced several image coding standards—JPEG for still image compression and H.261, MPEG-I and MPEG-II for video compression. While we have devoted a special section in this paper to cover international coding standards because of their practical value, we have also covered a large class of nonstandard coding technology in the interest of completeness and potential future value. Very low bit rate video coding remains a challenging problem as does our understanding of the human visual system for perceptually optimum compression. The wide range of applications and bit rates, from video telephony at rates as low as 9.6 kbps to HDTV at 20 Mbps and higher, has acted as a catalyst for generating new ideas in tackling the different challenges characterized by the particular application. The area of image compression will remain an interesting and fruitful area of research as we focus on combining source coding with channel coding and multimedia networking.
On the BRST Quantization of the Massless Bosonic Particle in Twistor-Like Formulation
Authors: Bandos Igor , Maznytsia Alexey , Rudychev Igor , Sorokin Dmitri 
Published: October 2003

We study some features of bosonic-particle path-integral quantization in a twistor-like approach by the use of the BRST–BFV-quantization prescription. In the course of the Hamiltonian analysis we observe links between various formulations of the twistor-like particle by performing a conversion of the Hamiltonian constraints of one formulation to another. A particular feature of the conversion procedure applied to turn the second-class constraints into first-class constraints is that the simplest Lorentz-covariant way to do this is to convert a full mixed set of the initial first- and second-class constraints rather than explicitly extracting and converting only the second-class constraints. Another novel feature of the conversion procedure applied below is that in the case of the D = 4 and D = 6 twistor-like particle the number of new auxiliary Lorentz-covariant coordinates, which one introduces to get a system of first-class constraints in an extended phase space, exceeds the number of independent second-class constraints of the original dynamical system. We calculate the twistor-like particle propagator in D = 3,4,6 space–time dimensions and show that it coincides with that of a conventional massless bosonic particle.
Form Factors for Principal Chiral Field Model with Wess–Zumino–Novikov–Witten Term
Authors: Mejean P. , Smirnov F. A. 
Published: October 2003

We construct the form factors of the trace of energy–momentum tensor for the massless model described by SU(2) principal chiral field model with WZNW term on level 1. We explain how this construction can be generalized to a class of integrable massless models including the flow from tricritical to critical Ising model. From F. Smirnov. During several months I worked with Pierre Mejean. After his premature decease which deeply affected everybody who knew him I decided to collect and to publish the results which we obtained together.
Precision Electroweak Data: Present Status and Future Prospects
Authors: Renton Peter B. 
Published: October 2003

The present status of precision electroweak data is reviewed. These data include LEP measurements of the mass and width of the Z, together with various measurements on the Z-fermion couplings. These data are compared to, and combined with, data from the SLC on the left–right polarized asymmetry, A LR , and the left–right forward–backward asymmetries for b and c quarks. These measurements are combined with hadron collider measurements from the Tevatron and CERN on the mass of the W boson, mW, as well as other electroweak data, in global electroweak fits in which various Standard Model parameters are determined. A comparison is made between the results of direct measurements of mW and the top-quark mass, mt, as determined from the Tevatron, with the indirect results coming from electroweak radiative corrections. Using all precision electroweak data, fits are also made to determine limits on the mass of the Higgs boson, mH. The influence on these limits of specific measurements, particularly those which are somewhat inconsistent with the Standard Model, is explored. The data are also analyzed in terms of the quasi model independent ∊ variables. Improvements in the determination of all of these quantities are expected when the Z data at LEP are fully analyzed, and further measurements on A LR and related asymmetries performed at the SLC. In addition, substantial improvements in the determination of mW are expected from measurements at the Tevatron and in the second phase of LEP. An estimate is made of the likely precision of these data, and the implications of the impact of these data on precision electroweak tests are discussed. This discussion is made both in terms of the Standard Model and also in the context of the quasi model independent ∊ variables.
The Rectangle Enclosure and Point-Dominance Problems Revisited
Authors: Gupta Prosenjit , Janardan Ravi , Smid Michiel , Dasgupta Bhaskar 
Published: October 2003

We consider the problem of reporting the pairwise enclosures in a set of n axes-parallel rectangles in ℝ 2, which is equivalent to reporting dominance pairs in a set of n points in ℝ 4. Over a decade ago, Lee and Preparata7 gave an O(n log n + k)-time and O(n)-space algorithm for these problems, where k is the number of reported pairs. Since that time, the question of whether there is a faster algorithm has remained an intriguing open problem. In this paper, we give an algorithm which uses O(n + k) space and runs in O(n log n log log n + k log log n) time. Thus, although our result is not a strict improvement over the Lee-Preparata algorithm for the full range of k, it is, nevertheless, the first result since Ref. (6) to make any progress on this long-standing open problem. Our algorithm is based on the divide-and-conquer paradigm. The heart of the algorithm is the solution to a red-blue dominance reporting problem (the "merge" step). We give a novel solution for this problem which is based on the iterative application of a sequence of non-trivial sweep routines. This solution technique should be of independent interest. We also present another algorithm whose bounds match the bounds given in Ref. (6), but which is simpler. Finally, we consider the special case where the rectangles have a small number, α, of different aspect ratios, which is often the case in practice. For this problem, we give an algorithm which runs in O(α n log n + k) time and uses O(n) space.
Relational Sets and Categorical Equivalence of Algebras
Authors: Zádori László 
Published: October 2003

We study relation varieties, i.e. classes of relational sets (resets) of the same type that are closed under the formation of products and retracts. The notions of an irreducible reset and a representation of a reset are defined similarly to the ones for partially ordered sets. We give a characterization of finite irreducible resets. We show that every finite reset has a representation by minimal resets which are certain distinguished irreducible retracts. It turns out that a representation by minimal resets is a smallest one in some sense among all representations of a reset. We prove that non-isomorphic finite irreducible resets generate different relation varieties. We characterize categorical equivalence of algebras via product and retract of certain resets associated with the algebras. In the finite case the characterization involves minimal resets. Examples are given to demonstrate how the general theorems work for particular algebras and resets.
Structure, Function, and Regulation of Budding Yeast Kinetochores
Authors: McAinsh Andrew D. , Tytell Jessica D. , Sorger Peter K. 
Published: October 2003

…S. cerevisiae centromeres represent the ultimate stage of centromere optimization… ( Malik & Henikoff 2002 ) Kinetochores are multiprotein complexes that assemble on centromeric DNA and mediate the attachment and movement of chromosomes along the microtubules (MTs) of the mitotic spindle. This review focuses on the simplest eukaryotic centromeres and kinetochores, those found in the budding yeast Saccharomyces cerevisiae. Research on kinetochore function and chromosome segregation is focused on four questions of general significance: What specifies the location of centromeres? What are the protein components of kinetochores, and how do they assemble a MT attachment site? How do MT attachments generate force? How do cells sense the state of attachment via the spindle assembly checkpoint?
Core Content for Residency Training in Child Abuse and Neglect
Authors: Starling Suzanne P. , Boos Stephen 
Published: October 2003

Since the identification of child abuse as a medical diagnosis, physicians have become resources to children, families, and communities to assist in diagnosing abuse, consulting with community agencies, testifying in courts of law, administering abuse prevention programs, and participating on teams to investigate and manage child abuse. Because the distribution of pediatric specialists in child abuse is limited, primary care physicians often are asked to perform these functions. Even in the face of this increasing demand, the education of physicians in the field of child abuse is very limited. Primary care residency programs can provide a good initial base to prepare physicians for forensic evaluations. This document outlines the basic elements of residency education in child abuse and neglect.
Functional endothelial cells derived from rhesus monkey embryonic stem cells
Authors: Kaufman Dan S. , Lewis Rachel L. , Hanson Eric T. , Auerbach Robert , Plendl Johanna , Thomson James A. 
Published: October 2003

AbstractWe have used rhesus monkey embryonic stem (ES) cells to study endothelial cell development. Rhesus ES cells (R366.4 cell line) exposed to medium containing vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), insulin-like growth factor (IGF), and epidermal growth factor (EGF) assumed a relatively uniform endothelial cell morphology and could be propagated and expanded with a consistent phenotype and normal karyotype. When placed in Matrigel, these rhesus ES cell–derived endothelial cells (RESDECs) formed capillary-like structures characteristic of endothelial cells. Immunohistochemical and flow cytometric analysis of RESDECs showed that they take up acetylated low-density lipoprotein (LDL), express CD146, von Willebrand factor, and the integrin αvβ3, and bind the lectin ulex europaeus agglutinin-1. These cells also express the VEGF receptor Flk-1 and secrete VEGF. When introduced in a Matrigel plug implanted subcutaneously in mice, RESDECs formed intact vessels and recruited new endothelial cell growth. In vivo function was demonstrated by coinjection of RESDECs with murine tumor cells subcutaneously into immunocompromised adult mice. RESDECs injected alone did not form measurable tumors. Tumor cells grew more rapidly and had increased vascularization when coinjected with the RESDECs. Immunohistochemical staining demonstrated that the RESDECs participated in forming the tumor neovasculature. RESDECs provide a novel means to examine the mechanisms of endothelial cell development, and may open up new therapeutic strategies.
Mechanism of protein sorting during erythroblast enucleation: role of cytoskeletal connectivity
Authors: Lee James C.-M. , Gimm J. Aura , Lo Annie J. , Koury Mark J. , Krauss Sharon W. , Mohandas Narla , Chasis Joel A. 
Published: October 2003

AbstractDuring erythroblast enucleation, nuclei surrounded by plasma membrane separate from erythroblast cytoplasm. A key aspect of this process is sorting of erythroblast plasma membrane components to reticulocytes and expelled nuclei. Although it is known that cytoskeletal elements actin and spectrin partition to reticulocytes, little is understood about molecular mechanisms governing plasma membrane protein sorting. We chose glycophorin A (GPA) as a model integral protein to begin investigating protein-sorting mechanisms. Using immunofluorescence microscopy and Western blotting we found that GPA sorted predominantly to reticulocytes. We hypothesized that the degree of skeletal linkage might control the sorting pattern of transmembrane proteins. To explore this hypothesis, we quantified the extent of GPA association to the cytoskeleton in erythroblasts, young reticulocytes, and mature erythrocytes using fluorescence imaged microdeformation (FIMD) and observed that GPA underwent dramatic reorganization during terminal differentiation. We discovered that GPA was more connected to the membrane cytoskeleton, either directly or indirectly, in erythroblasts and young reticulocytes than in mature cells. We conclude that skeletal protein association can regulate protein sorting during enucleation. Further, we suggest that the enhanced rigidity of reticulocyte membranes observed in earlier investigations results, at least in part, from increased connectivity of GPA with the spectrin-based skeleton.
Direct killing of Epstein-Barr virus (EBV)–infected B cells by CD4 T cells directed against the EBV lytic protein BHRF1
Authors: Landais Elise , Saulquin Xavier , Scotet Emmanuel , Trautmann Lydie , Peyrat Marie-Alix , Yates John L. , Kwok William W. , Bonneville Marc , Houssaint Elisabeth 
Published: October 2003

AbstractDue to their low frequency, CD4 T-cell responses to Epstein-Barr virus (EBV) lytic antigens are, so far, poorly characterized. Human peptide major histocompatibility complex (MHC) class II multimers provide a means to detect and characterize such rare T cells. Along a screening of T-cell responses to lytic or latent EBV antigens within peripheral blood leukocyte (PBL)– or synovial-derived CD4 T-cell lines, we identified an human leukocyte antigen–DR*0401 (HLA-DR*0401)–restricted epitope derived from BHRF1 (BamHI fragment H rightward open reading frame 1), a viral protein produced during the early stages of the lytic cycle. We show here that T-cell responses to this particular BHRF1 epitope are shared by most EBV-infected DR*0401+ individuals, as BHRF1-specific CD4 T cells could be sorted out from all the DRB*0401 T-cell lines analyzed, using magnetic beads coated with recombinant BHRF1/DR*0401 complexes. Sorting with these peptide MHC class II multimers was very efficient, as the yield of recovery of BHRF1-specific T cells was nearly 100%. Functional analysis of a large number of clones responding to BHRF1/DR*0401 demonstrated their cytolytic action against autologous and allogeneic DR*0401+ EBV-transformed B-lymphoblastoid cell lines (B-LCLs), with 40% to 80% killing efficiency and potent interferon γ production, thus suggesting that this CD4 T-cell population contributes to the control of EBV replication. B-LCL lysis by these T-cell clones was DR*0401 dependent, EBV dependent, and was not merely due to bystander killing. Taken together, these data provide the first demonstration that a lytic antigen can induce a direct cytolytic response against EBV-infected cells.
Localization of iron metabolism–related mRNAs in rat liver indicate that HFE is expressed predominantly in hepatocytes
Authors: Zhang An-Sheng , Xiong Shigang , Tsukamoto Hidekazu , Enns Caroline A. 
Published: October 2003

AbstractThe mRNAs of proteins involved in iron metabolism were measured in isolated hepatocytes, Kupffer cells, sinusoidal endothelial cells (SECs), and hepatic stellate cells (HSCs). Levels of type I hereditary hemochromatosis gene (HFE), transferrin, hepcidin, transferrin receptors 1 and 2 (TfR1, TfR2), ferroportin 1 (FPN1), divalent metal transporter 1 (DMT1), natural resistance–associated macrophage protein 1 (Nramp1), ceruloplasmin, hephaestin, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), were measured by quantitative reverse-transriptase polyerase chain reaction (qRT-PCR). We show that hepatocytes express almost all the iron-related genes tested, in keeping with their central role in iron metabolism. In addition, hepatocytes had 10-fold lower TfR1 mRNA levels than TfR2 and the lowest levels of TfR1 of the 4 cell types isolated. Kupffer cells, which process senescent red blood cells and recycle the iron, had high levels of ferroportin 1, ceruloplasmin, and hephaestin mRNA. Most important, of all the cell types tested, hepatocytes had the highest level of HFE mRNA, a factor of 10 higher than Kupffer cells. In situ hybridization analysis was conducted with rat liver sections. Consistent with the qRT-PCR analysis, HFE gene expression was localized mainly in hepatocytes. Western blot analysis confirmed this finding. Unexpectedly, HSCs also had high levels of DMT1 and ferroportin, implicating them in either iron sensing or iron cycling.
Herpes simplex virus type 1 activates murine natural interferon-producing cells through toll-like receptor 9
Authors: Krug Anne , Luker Gary D. , Barchet Winfried , Leib David A. , Akira Shizuo , Colonna Marco 
Published: October 2003

AbstractNatural interferon-producing cells (IPCs) specialize in the production of high levels of type 1 interferons (IFNs) in response to encapsulated DNA and RNA viruses. Here we demonstrate that the secretion of type 1 IFN in response to herpes simplex virus type 1 (HSV-1) in vitro is mediated by the toll-like receptor 9 (TLR9)/MyD88 pathway. Moreover, IPCs produce interleukin-12 (IL-12) in response to HSV-1 in vitro, which is also dependent on TLR9/ MyD88 signaling. Remarkably, though TLR9/MyD88-deficiency abrogates IPC responses to HSV-1 in vitro, mice lacking either MyD88 or TLR9 are capable of controlling HSV-1 replication in vivo after local infection, demonstrating that TLR9- and MyD88-independent pathways in cells other than IPCs can effectively compensate for defective IPC responses to HSV-1.
Antiangiogenic antithrombin down-regulates the expression of the proangiogenic heparan sulfate proteoglycan, perlecan, in endothelial cells
Authors: Zhang Weiqing , Chuang Yung-Jen , Swanson Richard , Li Juan , Seo Kyunga , Leung Lawrence , Lau Lester F. , Olson Steven T. 
Published: October 2003

AbstractAntithrombin, a key serpin family regulator of blood coagulation proteases, is transformed into a potent antiangiogenic factor by limited proteolysis or mild heating. Here, we show by cDNA microarray, semiquantitative reverse transcriptase–polymerase chain reaction (RT-PCR), Northern blotting, and immunoblotting analyses that the expression of the proangiogenic heparan sulfate proteoglycan (HSPG), perlecan, but not other HSPGs, is dramatically down-regulated in human umbilical vein endothelial cells (HUVECs) treated with antiangiogenic cleaved and latent forms of antithrombin but not with the native form. Down-regulation of perlecan expression by cleaved and latent antithrombins was observed in both basic fibroblast growth factor (bFGF)–stimulated and unstimulated cells, whereas the antiangiogenic antithrombins inhibited the proliferation of only bFGF-stimulated HUVECs by arresting cells at the G1 cell cycle phase. The importance of perlecan expression levels in mediating the antiproliferative effect of the antiangiogenic antithrombins was suggested by the finding that transforming growth factor-β1, a potent stimulator of perlecan expression in endothelial cells, blocked the down-regulation of perlecan expression and antiproliferative activity of cleaved antithrombin on endothelial cells. The previously established key role of perlecan in mediating bFGF stimulation of endothelial cell proliferation and angiogenesis suggests that a primary mechanism by which antiangiogenic antithrombins exert their effects is through the down-regulation of perlecan expression.