114 research outputs found
Some remarks on the hyperelliptic moduli of genus 3
In 1967, Shioda \cite{Shi1} determined the ring of invariants of binary
octavics and their syzygies using the symbolic method. We discover that the
syzygies determined in \cite{Shi1} are incorrect. In this paper, we compute the
correct equations among the invariants of the binary octavics and give
necessary and sufficient conditions for two genus 3 hyperelliptic curves to be
isomorphic over an algebraically closed field , . For
the first time, an explicit equation of the hyperelliptic moduli for genus 3 is
computed in terms of absolute invariants.Comment: arXiv admin note: text overlap with arXiv:1209.044
Magnetic order in the two-dimensional metal-organic framework manganese pyrazinecarboxylate with Mn-Mn dimers
The magnetic properties of [Mn(pyrazinecarboxylate)2]n (Mn-pyrazine),
empirical formula C10H6MnN4O4, are investigated through susceptibility, heat
capacity and neutron scattering measurements. The structure of Mn-pyrazine
consists of Mn-Mn dimers linked on a distorted 2D hexagonal structure. The weak
out of plane interactions create a quasi-2D magnetic material within the larger
three dimensional metal organic framework (MOF) structure. We show that this
material undergoes a two stage magnetic transition, related to the low
dimensionality of the Mn lattice. First at 5 K, which is assigned to the
initial development of short range order in the 2D layers. This is followed by
long range order at 3.3 K. Applied field measurements reveal the potential to
induce magnetic transitions in moderately small fields of 2 T. Neutron powder
diffraction enabled the determination of a unique magnetic space group P21'/c
(#14.77) at 1.5 K. This magnetic structure consists of antiferromagnetically
coupled Mn-Mn dimers with spins principally along the out of plane a-axis
SUPPORTING THE SRI LANKAN NATIVE BIRD SPECIES JUNGLE FOWL IN ANALOG FORESTRY
An experiment done at model Analog Forestry of BeJipola Estate, Mirahawatte, Sri Lankaindicates that an array of native and exotic crops deterinined by studies and trials madejungle fowl to re-establish, carry out main life activities and thrive in this anthropogenicecosystem of proper design
Spin-canting driven Weyl physics in EuCdAs
Though rare, magnetic Weyl semi-metals stand as the best platform to study
elusive Weyl physics as they can host the minimal allowable number of Weyl
points. Here we present neutron diffraction and density functional theory work
elucidating the magnetic structure realized in the candidate magnetic Weyl
semi-metal EuCdAs . Our work shows an unanticipated magnetic structure
(magnetic space group ) with an in-plane [210] moment direction and a
slight out-of-plane canting. This canted structure indicates that subtle tuning
(rather than a phase transition) may be able to stabilize the sought
c-polarized state. Our density functional theory work shows that though Weyl
physics should exist for a purely in-plane [210] structure, even a slight
canting drastically alters the relevant bands leading to well defined Weyl
points. Furthermore, we find that relative to the \textit{c}-polarized state
the [210] order with a small canting brings the Weyl points closer to the Fermi
level and thus may lead to clearer signatures of the Weyl physics.Comment: 7 pages, 4 figure
The RNA binding protein HuR does not interact directly with HIV-1 reverse transcriptase and does not affect reverse transcription in vitro
<p>Abstract</p> <p>Background</p> <p>Lemay <it>et al </it>recently reported that the RNA binding protein HuR directly interacts with the ribonuclease H (RNase H) domain of HIV-1 reverse transcriptase (RT) and influences the efficiency of viral reverse transcription (Lemay <it>et al</it>., 2008, Retrovirology 5:47). HuR is a member of the embryonic lethal abnormal vision protein family and contains 3 RNA recognition motifs (RRMs) that bind AU-rich elements (AREs). To define the structural determinants of the HuR-RT interaction and to elucidate the mechanism(s) by which HuR influences HIV-1 reverse transcription activity <it>in vitro</it>, we cloned and purified full-length HuR as well as three additional protein constructs that contained the N-terminal and internal RRMs, the internal and C-terminal RRMs, or the C-terminal RRM only.</p> <p>Results</p> <p>All four HuR proteins were purified and characterized by biophysical methods. They are well structured and exist as monomers in solution. No direct protein-protein interaction between HuR and HIV-1 RT was detected using NMR titrations with <sup>15</sup>N labeled HuR variants or the <sup>15</sup>N labeled RNase H domain of HIV-1 RT. Furthermore, HuR did not significantly affect the kinetics of HIV-1 reverse transcription <it>in vitro</it>, even on RNA templates that contain AREs.</p> <p>Conclusions</p> <p>Our results suggest that HuR does not impact HIV-1 replication through a direct protein-protein interaction with the viral RT.</p
The Macrocyclic Peptide Natural Product CJ-15,208 Is Orally Active and Prevents Reinstatement of Extinguished Cocaine-Seeking Behavior
The macrocyclic tetrapeptide natural product CJ-15,208 (cyclo[Phe-d-Pro-Phe-Trp]) exhibited both dose-dependent antinociception and kappa opioid receptor (KOR) antagonist activity after oral administration. CJ-15,208 antagonized a centrally administered KOR selective agonist, providing strong evidence it crosses the blood–brain barrier to reach KOR in the CNS. Orally administered CJ-15,208 also prevented both cocaine- and stress-induced reinstatement of extinguished cocaine-seeking behavior in the conditioned place preference assay in a time- and dose-dependent manner. Thus, CJ-15,208 is a promising lead compound with a unique activity profile for potential development, particularly as a therapeutic to prevent relapse to drug-seeking behavior in abstinent subjects
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