1,625 research outputs found
Higher anisotropic d-wave symmetry in cuprate superconductors
We derive a pair potential from tight binding further neighbours attraction
that leads to superconducting gap symmetry similar to that of the
phenomenological spin fluctuation theory of high temperature superconductors
(Monthoux, Balatsky, Pines, Phys. Rev. Lett. {\bf 67}, 3448). We show that
higher anisotropic d-wave than the simpliest d-wave symmetry is one of the
important ingredients responsible for higher BCS characteristic ratio.Comment: Latex 5 pages, 3 figures attached, Journal Ref. : Journal of Physics
C, Vol. 11, issue 30, L371-L377 (1999
A negatively charged region of the skeletal muscle ryanodine receptor is involved in Ca2+-dependent regulation of the Ca2+ release channel
AbstractThe ryanodine receptor/Ca2+ release channels from skeletal (RyR1) and cardiac (RyR2) muscle cells exhibit different inactivation profiles by cytosolic Ca2+. D3 is one of the divergent regions between RyR1 (amino acids (aa) 1872–1923) and RyR2 (aa 1852–1890) and may contain putative binding site(s) for Ca2+-dependent inactivation of RyR. To test this possibility, we have deleted the D3 region from RyR1 (ΔD3-RyR1), residues 1038–3355 from RyR2 (Δ(1038–3355)-RyR2) and inserted the skeletal D3 into Δ(1038–3355)-RyR2 to generate sD3-RyR2. The channels formed by ΔD3-RyR1 and Δ(1038–3355)-RyR2 are resistant to inactivation by mM [Ca2+], whereas the chimeric sD3-RyR2 channel exhibits significant inactivation at mM [Ca2+]. The ΔD3-RyR1 channel retains its sensitivity to activation by caffeine, but is resistant to inactivation by Mg2+. The data suggest that the skeletal D3 region is involved in the Ca2+-dependent regulation of the RyR1 channel
Superfluid, Mott-Insulator, and Mass-Density-Wave Phases in the One-Dimensional Extended Bose-Hubbard Model
We use the finite-size density-matrix-renormalization-group (FSDMRG) method
to obtain the phase diagram of the one-dimensional () extended
Bose-Hubbard model for density in the plane, where and
are, respectively, onsite and nearest-neighbor interactions. The phase diagram
comprises three phases: Superfluid (SF), Mott Insulator (MI) and Mass Density
Wave (MDW). For small values of and , we get a reentrant SF-MI-SF phase
transition. For intermediate values of interactions the SF phase is sandwiched
between MI and MDW phases with continuous SF-MI and SF-MDW transitions. We
show, by a detailed finite-size scaling analysis, that the MI-SF transition is
of Kosterlitz-Thouless (KT) type whereas the MDW-SF transition has both KT and
two-dimensional-Ising characters. For large values of and we get a
direct, first-order, MI-MDW transition. The MI-SF, MDW-SF and MI-MDW phase
boundaries join at a bicritical point at (.Comment: 10 pages, 15 figure
Genome maps across 26 human populations reveal population-specific patterns of structural variation.
Large structural variants (SVs) in the human genome are difficult to detect and study by conventional sequencing technologies. With long-range genome analysis platforms, such as optical mapping, one can identify large SVs (>2 kb) across the genome in one experiment. Analyzing optical genome maps of 154 individuals from the 26 populations sequenced in the 1000 Genomes Project, we find that phylogenetic population patterns of large SVs are similar to those of single nucleotide variations in 86% of the human genome, while ~2% of the genome has high structural complexity. We are able to characterize SVs in many intractable regions of the genome, including segmental duplications and subtelomeric, pericentromeric, and acrocentric areas. In addition, we discover ~60 Mb of non-redundant genome content missing in the reference genome sequence assembly. Our results highlight the need for a comprehensive set of alternate haplotypes from different populations to represent SV patterns in the genome
Model for Glass Transition in a Binary fluid from a Mode Coupling approach
We consider the Mode Coupling Theory (MCT) of Glass transition for a Binary
fluid. The Equations of Nonlinear Fluctuating Hydrodynamics are obtained with a
proper choice of the slow variables corresponding to the conservation laws. The
resulting model equations are solved in the long time limit to locate the
dynamic transition. The transition point from our model is considerably higher
than predicted in existing MCT models for binary systems. This is in agreement
with what is seen in Computer Simulation of binary fluids. fluids.Comment: 9 Pages, 3 Figure
Methods for the Detection, Study, and Dynamic Profiling of O-GlcNAc Glycosylation
The addition of O-linked β-N-acetylglucosamine (O-GlcNAc) to serine/threonine residues of proteins is a ubiquitous posttranslational modification found in all multicellular organisms. Like phosphorylation, O-GlcNAc glycosylation (O-GlcNAcylation) is inducible and regulates a myriad of physiological and pathological processes. However, understanding the diverse functions of O-GlcNAcylation is often challenging due to the difficulty of detecting and quantifying the modification. Thus, robust methods to study O-GlcNAcylation are essential to elucidate its key roles in the regulation of individual proteins, complex cellular processes, and disease. In this chapter, we describe a set of chemoenzymatic labeling methods to (1) detect O-GlcNAcylation on proteins of interest, (2) monitor changes in both the total levels of O-GlcNAcylation and its stoichiometry on proteins of interest, and (3) enable mapping of O-GlcNAc to specific serine/threonine residues within proteins to facilitate functional studies. First, we outline a procedure for the expression and purification of a multiuse mutant galactosyltransferase enzyme (Y289L GalT). We then describe the use of Y289L GalT to modify O-GlcNAc residues with a functional handle, N-azidoacetylgalactosamine (GalNAz). Finally, we discuss several applications of the copper-catalyzed azide-alkyne cycloaddition “click” reaction to attach various alkyne-containing chemical probes to GalNAz and demonstrate how this functionalization of O-GlcNAc-modified proteins can be used to realize (1)–(3) above. Overall, these methods, which utilize commercially available reagents and standard protein analytical tools, will serve to advance our understanding of the diverse and important functions of O-GlcNAcylation
Metastable Dynamics of the Hard-Sphere System
The reformulation of the mode-coupling theory (MCT) of the liquid-glass
transition which incorporates the element of metastability is applied to the
hard-sphere system. It is shown that the glass transition in this system is not
a sharp one at the special value of the density or the packing fraction, which
is in contrast to the prediction by the conventional MCT. Instead we find that
the slowing down of the dynamics occurs over a range of values of the packing
fraction. Consequently, the exponents governing the sequence of time
relaxations in the intermediate time regime are given as functions of packing
fraction with one additional parameter which describes the overall scale of the
metastable potential energy for defects in the hard-sphere system. Implications
of the present model on the recent experiments on colloidal systems are also
discussed.Comment: 21 pages, 5 figures (available upon request), RevTEX3.0, JFI
Preprint
Telomerase activity and telomere length in primary and metastatic tumors from pediatric bone cancer patients
The presence of telomerase activity has been analyzed in almost all tumor types and tumor-derived cell lines. However, there are very few studies that focus on the presence of telomerase activity in bone tumors, and most of them report analysis on very few samples or bone-derived cell lines. The objective of this study was to analyze the telomere length and telomerase activity in primary tumors and metastatic lesions from pediatric osteosarcoma and Ewing's sarcoma patients. The presence of telomerase activity was analyzed by the telomeric repeat amplification protocol assay, and the telomere length was measured by Southern blot. Results were related to survival and clinical outcome. Telomerase activity was detected in 85% of the bone tumor metastases (100% Ewing's sarcomas and 75% osteosarcomas) but only in 12% of the primary tumors (11.1% osteosarcomas and 12.5% Ewing's sarcomas). Bone tumor tissues with telomerase activity had mean telomere lengths 3 kb shorter than those with no detectable telomerase activity (p = 0.041). The presence of telomerase activity was associated with survival (p = 0.009), and longer event-free survival periods were found in patients who lacked telomerase activity compared with those who had detectable telomerase activity levels in their tumor tissues (p = 0.037). The presence of longer telomeres in primary pediatric bone tumors than in metastases could be indicative of alternative mechanisms of lengthening of telomeres for their telomere maintenance rather than telomerase activity. Nevertheless, the activation of telomerase seems to be a crucial step in the malignant progression and acquisition of invasive capability of bone tumors
Signals for a Transition from Surface to Bulk Emission in Thermal Multifragmentation
Excitation-energy-gated two-fragment correlation functions have been studied
between 2 to 9A MeV of excitation energy for equilibrium-like sources formed in
and p + Au reactions at beam momenta of 8,9.2 and 10.2 GeV/c.
Comparison of the data to an N-body Coulomb-trajectory code shows a decrease of
one order of magnitude in the fragment emission time in the excitation energy
interval 2-5A MeV, followed by a nearly constant breakup time at higher
excitation energy. The observed decrease in emission time is shown to be
strongly correlated with the increase of the fragment emission probability, and
the onset of thermally-induced radial expansion. This result is interpreted as
evidence consistent with a transition from surface-dominated to bulk emission
expected for spinodal decomposition.Comment: 11 pages including 3 postscript figures (1 color
Immune-mediated mechanisms influencing the efficacy of anticancer therapies
Conventional anticancer therapies, such as chemotherapy, radiotherapy, and targeted therapy, are designed to kill cancer cells. However, the efficacy of anticancer therapies is not only determined by their direct effects on cancer cells but also by off-target effects within the host immune system. Cytotoxic treatment regimens elicit several changes in immune-related parameters including the composition, phenotype, and function of immune cells. Here we discuss the impact of innate and adaptive immune cells on the success of anticancer therapy. In this context we examine the opportunities to exploit host immune responses to boost tumor clearing, and highlight the challenges facing the treatment of advanced metastatic disease
- …