4,739 research outputs found
Spectra of phase point operators in odd prime dimensions and the extended Clifford group
We analyse the role of the Extended Clifford group in classifying the spectra
of phase point operators within the framework laid out by Gibbons et al for
setting up Wigner distributions on discrete phase spaces based on finite
fields. To do so we regard the set of all the discrete phase spaces as a
symplectic vector space over the finite field. Auxiliary results include a
derivation of the conjugacy classes of .Comment: Latex, 19page
The Schwinger SU(3) construction - I: Multiplicity problem and relation to induced representations
The Schwinger oscillator operator representation of SU(3) is analysed with
particular reference to the problem of multiplicity of irreducible
representations. It is shown that with the use of an unitary
representation commuting with the SU(3) representation, the infinity of
occurrences of each SU(3) irreducible representation can be handled in complete
detail. A natural `generating representation' for SU(3), containing each
irreducible representation exactly once, is identified within a subspace of the
Schwinger construction; and this is shown to be equivalent to an induced
representation of SU(3).Comment: Latex, 25 page
q-deformed dynamics and Josephson junction
We define a generalized rate equation for an observable in quantum mechanics,
that involves a parameter q and whose limit gives the standard
Heisenberg equation. The generalized rate equation is used to study dynamics of
current biased Josephson junction. It is observed that this toy model
incorporates diffraction like effects in the critical current. Physical
interpretation for q is provided which is also shown to be q-deformation
parameter.Comment: LaTeX 9 pages, submitted Mod. Phys. Lett. B, e-mail: [email protected]
Confinement and Viscoelastic effects on Chain Closure Dynamics
Chemical reactions inside cells are typically subject to the effects both of
the cell's confining surfaces and of the viscoelastic behavior of its contents.
In this paper, we show how the outcome of one particular reaction of relevance
to cellular biochemistry - the diffusion-limited cyclization of long chain
polymers - is influenced by such confinement and crowding effects. More
specifically, starting from the Rouse model of polymer dynamics, and invoking
the Wilemski-Fixman approximation, we determine the scaling relationship
between the mean closure time t_{c} of a flexible chain (no excluded volume or
hydrodynamic interactions) and the length N of its contour under the following
separate conditions: (a) confinement of the chain to a sphere of radius D, and
(b) modulation of its dynamics by colored Gaussian noise. Among other results,
we find that in case (a) when D is much smaller than the size of the chain,
t_{c}\simND^{2}, and that in case (b), t_{c}\simN^{2/(2-2H)}, H being a number
between 1/2 and 1 that characterizes the decay of the noise correlations. H is
not known \`a priori, but values of about 0.7 have been used in the successful
characterization of protein conformational dynamics. At this value of H
(selected for purposes of illustration), t_{c}\simN^3.4, the high scaling
exponent reflecting the slow relaxation of the chain in a viscoelastic medium
Particle alignments and shape change in Ge and Ge
The structure of the nuclei Ge and Ge is studied
by the shell model on a spherical basis. The calculations with an extended
Hamiltonian in the configuration space
(, , , ) succeed in reproducing
experimental energy levels, moments of inertia and moments in Ge isotopes.
Using the reliable wave functions, this paper investigates particle alignments
and nuclear shapes in Ge and Ge.
It is shown that structural changes in the four sequences of the positive-
and negative-parity yrast states with even and odd are caused by
various types of particle alignments in the orbit.
The nuclear shape is investigated by calculating spectroscopic moments of
the first and second states, and moreover the triaxiality is examined by
the constrained Hatree-Fock method.
The changes of the first band crossing and the nuclear deformation depending
on the neutron number are discussed.Comment: 18 pages, 21 figures; submitted to Phys. Rev.
Temperature effects on mixed state geometric phase
Geometric phase of an open quantum system that is interacting with a thermal
environment (bath) is studied through some simple examples. The system is
considered to be a simple spin-half particle which is weakly coupled to the
bath. It is seen that even in this regime the geometric phase can vary with
temperature. In addition, we also consider the system under an adiabatically
time-varying magnetic field which is weakly coupled to the bath. An important
feature of this model is that it reveals existence of a temperature-scale in
which adiabaticity condition is preserved and beyond which the geometric phase
is varying quite rapidly with temperature. This temperature is exactly the one
in which the geometric phase vanishes. This analysis has some implications in
realistic implementations of geometric quantum computation.Comment: 5 page
Formulation and Evaluation of Polyherbal Anthelmintic Preparation
The present study was done with the aim to formulate an anthelmintic preparation and to evaluate anthelmintic activity of formulation containing traditionally user herbs viz., Plumbago zeylanica (leaves), Hyoscyamus niger (roots) and Abultion indicum (leaves) using adult earthworm Pheritima posthuma. The aqueous and ethanolic extract of the crude drug of different concentration were tested which involve determination of paralysis time and time to kill the worms. Piperazine citrate was used as standard and it was found that the PHFEE activity is higher than PHFAE
Tissue localization of collagenase and leucine aminopeptidase in the bovine filarial parasite Setaria cervi
BACKGROUND: Like other helminth proteases, filarial proteases have also been shown to require for parasite survival inside the host and mediate various physiologic processes such as tissue invasion, feeding, embryogenesis and host immune evasion. Many of these proteases have shown potential for vaccines and chemotherapeutic agents against active filarial infections. Setaria cervi is a bovine filarial parasite and serves as a good parasite model for the studies in lymphatic filariasis. Recently, a 175 kDa collagenase and leucine aminopeptidase (LAP) have been purified and characterized from the bovine filarial parasite S. cervi and shown to be potential vaccine candidate and diagnostic marker, respectively for human lymphatic filariasis. However, their tissue localizations and putative roles in the parasite biology have not yet been examined and thus remain unclear. Therefore, the current study attempts to localize and explore the putative roles of these two enzymes in S. cervi. METHODS: The tissue distributions of 175 kDa collagenase and leucine aminopeptidase in S. cervi were examined by immunohistochemical and histochemical methods, respectively. Immune sera obtained from the jirds immunized with collagenase served as primary antibody, rabbit anti-mouse IgG-HRP conjugate as secondary antibody and DAB as the substrate for the immunostaining of collagenase. Leu-βNA was used as the substrate for the histochemical staining of LAP. RESULTS: Both the collagenase and LAP were present in the body wall; however, they differ in their distribution pattern in different layers of body wall. Collagenase was mainly localized in epicuticle, cuticle, syncytial hypodermis and the nerve cord region whereas LAP was more concentrated in epicuticle, longitudinal muscle layers and almost absent or very faintly stained in syncytial hypodermis and nerve cord region. Both collagenase and LAP showed their common distributions in intestine, uterus and mature eggs, growing embryos and mf. Very strong immunostaining of collagenase in the outer body surface of the parasite indicates its major role in host-parasite relationship whereas the presence of LAP in muscular region suggests its role in tissue remodeling. The common presences of collagenase and LAP in the S. cervi intestine, ovary, uterus, eggs and mf suggest that they also have collaborative roles in molting, nutrition and embryogenesis. The data obtained on their immunological characterizations and their presence in important parasite organs give strong indication that they are critical for the survival of filarial parasite and thus can be good vaccine candidates and/or diagnostic markers for human lymphatic filariasis. CONCLUSION: The manuscript reports for the first time the tissue distribution of collagenase and LAP in the bovine filarial parasite S. cervi and discuss their putative roles in vivo. Our findings also open the avenue to examine the roles of these two proteases in vivo, which will require further experiments like using their natural substrates and/or specific inhibitors in each tissues
Molecular dissection of the mechanism by which EWS/FLI expression compromises actin cytoskeletal integrity and cell adhesion in Ewing sarcoma.
Ewing sarcoma is the second-most-common bone cancer in children. Driven by an oncogenic chromosomal translocation that results in the expression of an aberrant transcription factor, EWS/FLI, the disease is typically aggressive and micrometastatic upon presentation. Silencing of EWS/FLI in patient-derived tumor cells results in the altered expression of hundreds to thousands of genes and is accompanied by dramatic morphological changes in cytoarchitecture and adhesion. Genes encoding focal adhesion, extracellular matrix, and actin regulatory proteins are dominant targets of EWS/FLI-mediated transcriptional repression. Reexpression of genes encoding just two of these proteins, zyxin and α5 integrin, is sufficient to restore cell adhesion and actin cytoskeletal integrity comparable to what is observed when the EWS/FLI oncogene expression is compromised. Using an orthotopic xenograft model, we show that EWS/FLI-induced repression of α5 integrin and zyxin expression promotes tumor progression by supporting anchorage-independent cell growth. This selective advantage is paired with a tradeoff in which metastatic lung colonization is compromised
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