Search Results - (Author, Cooperation:S. K. Mishra)

2013-05-25

American Association for the Advancement of Science (AAAS)

0036-8075

1095-9203

Biology

Chemistry and Pharmacology

Computer Science

Medicine

Natural Sciences in General

Physics

Animals ; Chloroquine/pharmacology ; Endothelin-1/pharmacology ; Gastrin-Releasing Peptide/metabolism/pharmacology ; Histamine/pharmacology ; Male ; Mice ; Mice, Inbred C57BL ; Mice, Knockout ; Natriuretic Peptide, Brain/genetics/*metabolism/pharmacology ; *Nociception ; Phospholipase C beta ; Pruritus/chemically induced/metabolism/*physiopathology ; Receptors, Atrial Natriuretic Factor/metabolism ; Sensory Receptor Cells/drug effects/*metabolism ; Spinal Cord/drug effects/pathology/physiopathology ; TRPV Cation Channels/metabolism

2013-07-19

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Animals ; Apoproteins/chemistry ; Arachidonic Acid/metabolism ; Biological Transport ; Carrier Proteins/chemistry/genetics/*metabolism ; Cell Membrane/metabolism ; Cell Nucleus/metabolism ; Ceramides/chemistry/*metabolism ; Crystallography, X-Ray ; Cytosol/metabolism ; Eicosanoids/*metabolism ; Humans ; Hydrophobic and Hydrophilic Interactions ; Mice ; Models, Molecular ; Phosphatidic Acids/chemistry/metabolism ; Protein Conformation ; Protein Folding ; Substrate Specificity ; trans-Golgi Network/metabolism

2018-09-05

American Physical Society (APS)

1098-0121

1095-3795

Physics

Dynamics, dynamical systems, lattice effects

2011-05-27

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

*Alternative Splicing ; Amino Acid Sequence ; Binding Sites ; Cell Line ; Gene Deletion ; *Gene Expression Regulation, Fungal ; Humans ; Ligases/deficiency/genetics/*metabolism ; Membrane Proteins/genetics ; Models, Molecular ; Molecular Sequence Data ; Nuclear Proteins/genetics ; Protein Binding ; Protein Conformation ; RNA Splice Sites/*genetics ; RNA, Fungal/*genetics/metabolism ; RNA, Messenger/genetics/metabolism ; Ribonucleoprotein, U4-U6 Small Nuclear/deficiency/genetics ; Ribonucleoprotein, U5 Small Nuclear/deficiency/genetics ; Ribonucleoproteins, Small Nuclear/chemistry/deficiency/genetics/metabolism ; Saccharomyces cerevisiae/chemistry/*genetics/*metabolism ; Saccharomyces cerevisiae Proteins/chemistry/genetics/*metabolism ; Schizosaccharomyces/chemistry/genetics/metabolism ; Schizosaccharomyces pombe Proteins/genetics/metabolism ; Spliceosomes/chemistry/metabolism ; Ubiquitin-Protein Ligase Complexes/deficiency/genetics/metabolism

1474-8673

Blackwell Publishing Journal Backfiles 1879-2005

Chemistry and Pharmacology

Medicine

1 The present study was carried out to characterize the effect of adenosine on calcium dynamics in the rat portal vein. Isolated portal vein of male albino rats was used as the experimental model as it exhibits autorhythmicity. Adenosine and its analogues 2-CAD, N6-CHA and NECA were used to characterize the type of adenosine receptor involved and 2-CAD was used along with adenosine throughout the other part of study to characterize the effect of adenosine on Ca2+ dynamics.2 Adenosine and its analogues were found to inhibit the spontaneous contractions of rat portal vein in a concentration-related manner. The order of potency was NECA 〉 2-CAD 〉 N6-CHA 〉 adenosine. Incubation of the tissue with CGS∼15943A, an adenosine receptor antagonist, had a per se enhancing effect on autorhythmicity. Adenosine and 2-CAD failed to reverse the contractile response produced by hypertonic KCl (80 or 30 mm). Whereas adenosine and 2-CAD effectively relaxed the tissues contracted with phenylephrine (10−5 m).3 Preincubation of the tissue with 2-CAD (10−4, 10−5 or 10−6 m) for 5 min raised the threshold concentration of CaCl2 to evoke contractile response and also significantly increased the mean EC50 values of CaCl2. Nifedipine was found to be more potent than 2-CAD on Ca2+ channels.4 The results of the present study suggest that the endogenous adenosine plays a significant role in producing vascular relaxation through the participation of A2 receptor subtype. This effect may be due to its inhibitory effect on release of Ca2+ from the intracellular stores. Further to this effect, 2-CAD had a major inhibitory effect on voltage-operated Ca2+ channels compared with receptor-operated Ca2+ channels.5 It can be concluded that adenosine through its A2 receptor produces vasorelaxant effect by interfering with the release of Ca2+ from the intracellular stores coupled with influx of Ca2+ from the extracellular sources.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

The nature of the Verwey transition in magnetite (Fe3O4) within a three-band spinless model Hamiltonian is examined. These bands, which arise from the minority-spin t2g orbitals on the Fe(B) sublattice, are occupied by half an electron per Fe(B) atom. The Verwey order–disorder transition is studied as a function of the ratio of the intersite Coulomb repulsion U1 and the bandwidth W. It is found that the electrons are ordered beyond the critical value of U1/W≈0.25 in essential agreement with the results of the one-band Cullen–Callen model. For larger values of U1/W, a Verwey-like order is exhibited where the electrons occupy alternate (001) planes. The model predicts a transition from the metallic to the semiconducting state with the band gap increasing linearly with U1 beyond the transition point.

Electronic Resource

1089-7550

AIP Digital Archive

Physics

We examine the magnetic and structural properties of the lanthanum manganite-based double-exchange magnets exhibiting colossal magnetoresistance. A model Hamiltonian containing the double-exchange, superexchange, and the Hubbard terms, with parameters obtained from density–functional calculations (Ref. 1), is studied within a mean-field approximation both at temperature T=0 and T〉0 and with the effects of the magnetic field included. The phase diagrams we obtain with magnetic and charge-ordered phases enable us to examine the competition between the double- and superexchange terms as functions of doping and temperature. Our theoretical study provides a qualitative understanding of the phase diagram observed in the experiments. © 1997 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

The temperature variation of planar electromechanical coupling coefficient (kp) in Pb(ZrxTi1−x)O3(PZT) ceramics near the morphotropic phase boundary (MPB) compositions has been correlated with structural changes to show that the maximum electromechanical response at a given composition (x) is a function of temperature (T) and occurs in the tetragonal phase field just outside the two-phase MPB region in the (x,T) plane. This clearly disproves the hypothesis that the coexistence of rhombohedral and tetragonal phases at MPB is responsible for the enhancement of the electromechanical response. In fact, coexistence of the rhombohedral phase with the tetragonal phase is shown to lead to the lowering of the electromechanical response. © 1996 American Institute of Physics.

Electronic Resource

1077-3118

AIP Digital Archive

Physics

A pyrophoric technique using an explosive exothermic reaction has been developed to yield calcined and microscopically homogeneous (0.3 μm size) powders of multicomponent cuprate systems. The technique has been used to synthesize superconducting materials of variable composition of the type M1M2⋅⋅⋅MnOx. The bulk materials prepared from these powders show sharp (1 K) superconducting transitions and nearly ideal Meissner effect.

Electronic Resource

1436-5065

Springer Online Journal Archives 1860-2000

Geography

Physics

Zusammenfassung Eine lineare, barokline Stabilitätsanalyse wird auf das vertikale, zonale Windprofil der Grundströmung vor der Bildung einer Depression während der MONEX-79-Phase in der Bucht von Bengalen angewendet, wobei ein quasi-geostrophisches, mehrschichtiges, numerisches Modell verwendet wird. Die aus der Zuwachsrate des Spektrums abgeleitete, bevorzugte Wellenlänge beträgt 1400 km für eine Kanalbreite von 1500 km und eine e-fache Vergrößerungszeit von 5.2 Tagen. Die vertikale Wellenstruktur wurde berechnet und mit der beobachteten Struktur der Depression verglichen. Beide besitzen mehrere gemeinsame Grundzüge. Die vertikale Struktur der bevorzugten Welle, aus einem modifizierten Windprofil abgeleitet, in dem die Windscherung unterhalb des Westwindmaximums entfernt wurde, zeigt bessere Übereinstimmung mit der Depressionsstruktur, als die aus dem vollen Windprofil erhaltene Struktur. Der Effekt der vertikalen Veränderlichkeit der statischen Stabilität in den unteren Schichten auf das Wachstum der kurzen, instabilen Wellen wird untersucht. Es zeigt sich, daß eine Abnahme der statischen Stabilität in den unteren Schichten zu einer Zunahme der Wachstumsrate und einer Abnahme der bevorzugten Wellenlänge führt.

Summary A linear baroclinic stability analysis is performed for the basic vertical zonal wind profile prior to the formation of the depression during Bay of Bengal phase of MONEX-79 by utilizing a quasi- geostrophic, multilayer, numerical model. The preferred wavelength obtained from the growth rate spectrum is 1400 km for the channel width 1500 km, with an e-folding time 5.2 days. The wave structure in the vertical is computed and compared with the observed structure of the depression. Many common features are noticed between them. Further, the vertical structure of the preferred wave obtained from the modified wind profile, removing wind shear below the westerly maximum level, shows closer agreement to the depression structure than that obtained from the full profile. The effect of vertical variation of static stability in the lower layers on the growth of short unstable waves is studied. It is found that a decrease in static stability in the lower layers resulted in the increase in growth rate and decrease in the preferred wavelength.

Electronic Resource

1436-5065

Springer Online Journal Archives 1860-2000

Geography

Physics

Zusammenfassung Ein quasigeostrophisches lineares baroklines diabatisches Modell, das auch die Oberflächenreibung und die Orographie miteinschließt, wird zur Bestimmung der verschiedenen geophysikalischen Prozesse, die für die Westwärtsverlagerung von Monsun-Depressionen in der unteren Troposphäre maßgebend sind, angewendet. Für diesen Zweck wird in Annäherung an den mittleren beobachteten Zustand einer Monsun-Depression das Geopotential durch analytische Funktionen für die Ausgangszeit vorgeschrieben. w wird als analytische Lösung der Omega-Gleichung für verschiedene physikalische Prozesse erhalten und mit den beobachteten Verteilungen verglichen. Die Bedeutung der Orographie für die Veranlassung der Westwärtswanderung der Welle wird untersucht; sie wurde als am bedeutungsvollsten in der Grundschicht befunden. Die Laplace'sche thermische Advektion und die differentiale Vorticity-Advektion sind zwei andere wichtige physikalische Prozesse, die für die Bewegung nach Westen in der Grundschicht maßgebend sind. Aus den Ergebnissen wird die Notwendigkeit eines vertikalen Transportes von zyklonischer Vorticity vor einer Monsun-Depression von der Grundschicht zur oberen Schicht abgeleitet. Die für die Verlagerung der Welle nach Norden maßgebenden physikalischen Prozesse werden ebenfalls bestimmt.

Summary A quasi-geostrophic, linear, barochnic, diabatic model, which also includes the surface friction and the orography is utilized for identifying the various physical processes responsible for the westward motion of monsoon depression in the lower troposphere. For this purpose, the geopotential, resembling the mean observed state of a monsoon depression, is prescribed by analytical functions at an initial time. w is obtained as the analytic solution of the omega equation for the various physical processes and it is compared with the observed distributions. The role of orography in inducing the westward motion to the wave is investigated and found to be most important in the boundary layer. The Laplacian of thermal advection and the differential vorticity advection are the other two important physical processes responsible for the movement of wave in the westward direction in the boundary layer. The necessity for the vertical transport of cyclonic vorticity ahead of monsoon depression from the boundary layer to the upper layer is inferred from the results. The physical processes responsible for the northward motion of the wave are also identified.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract Self-similar flows of a gas, moving under the gravitational force of attraction behind a spherical shock wave, which are driven out by a propelling contact surface and propagating into a uniform atmosphere at rest are investigated. The energy of the expanding wave has been assumed to be time-dependent, obeying a power law. In the last section the self-similar homothermal flows of self-gravitating gas has been also discussed. A comparative study has been made between the nature of flow variables for adiabatic and homothermal flows.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract A propagation of diverging cylindrical shock in a self-gravitating gas, having an initial density and azimuthal magnetic field distributions variable, has been studied for the two cases (i) when the shock is weak and (ii) when it is strong. Analytical relations for shock velocity and shock strength have been obtained. Lastly, the expressions for the pressure, the density and the particle velocity immediately behind the shock have been also obtained for both cases.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract Non-self-similar isothermal flows behind weak cylindrical shock waves are investigated. The shock is assumed to be propagating in a medium at rest with uniform density permeated by a uniform transverse magnetic field. The electrical conductivity of the gas is infinite everywhere. The total energy of the disturbance is not constant but can be made to increase at a slow rate. A comparative study has been made between the results with an without a magnetic field.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract A self-similar solution to the problem of the implosion of a cylindrical shock wave in the presence of a magnetic field has been investigated. A strong shock wave in a cylindrically-symmetric flow travels to the axis of symmetry through a gas of uniform initial density ρ0 and zero-pressure. A comparative study has been made between the results obtained in ordinary gasdynamics and magnetogasdynamics with transverse and axial components of the magnetic field. The value of similarity exponent α has been assigned from that found in the paper of Whitham (1958).

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract Self-similar flows of a perfect gas behind a cylindrical blast wave with radiation heat flux in the presence of an azimuthal magnetic field have been investigated. The effects of radiation flux and magnetic field together on the other flow variables have been studied in the region of interest. The magnetic field and density distribution vary as an inverse power of radial distance from the axis of symmetry. The electrical conductivity of the gas is taken to be infinite. The total energy of the flow between the inner expanding surface and the shock is assumed to be constant. We also have supposed the gas to be grey and opaque and the shock to be transparent and isothermal.

Electronic Resource

1572-946X

Springer Online Journal Archives 1860-2000

Physics

Abstract The effect of the disturbance behind a strong plane shock wave propagating in a medium with exponentially varying density in the presence of magnetic field is investigated. The similarity solution is used to find the two interaction terms at all points of the flow. A method has been developed to determine the similarity exponent α in magnetogasdynamics.

Electronic Resource

1432-0800

Springer Online Journal Archives 1860-2000

Energy, Environment Protection, Nuclear Power Engineering

Medicine

Electronic Resource

1436-5065

Springer Online Journal Archives 1860-2000

Geography

Physics

Zusammenfassung Die durchschnittliche dreidimensionale Struktur von Monsun-Depressionen wird mathematisch als quasigeostrophische horizontale zweidimensionale Wellenstörung ohne Neigung in der Vertikalen und Horizontalen mit durchschnittlichen Wellenlängen von 2000 und 1500 km in zonalen und meridionalen Richtungen dargestellt. Die Wellenamplitude hat ihr Maximum im 700 mb-Niveau und ihre vertikale Änderung ist durch eine polynome Funktion vonp repräsentiert. Die Temperaturwelle und die Verteilungen des zonalen und meridionalen Windes in der zonalen Fläche werden mit den beobachteten, mit Monsun-Depressionen verbundenen Verteilungen verglichen und in guter Übereinstimmung mit diesen gefunden. Vertikale Profile der konvektiven Erwärmung werden durch polynome Funktionen vonp dargestellt.

Summary The average three-dimensional structure of monsoon depressions is represented mathematically as a quasi-geostrophic horizontal two-dimensional wave perturbation, having no tilt in vertical and in horizontal, with average wavelengths of 2000 km and 1500 km in the zonal and meridional directions, respectively. The wave amplitude is maximum at 700 mb and its vertical variation is represented by a polynomial function ofp. The wave temperature, the zonal and meridional wind distributions in the zonal plane are compared with the observed distributions associated with monsoon depressions, and a good agreement between them is noticed. Vertical profiles of the convective heating are represented by polynomial functions ofp.

Electronic Resource

1436-5065

Springer Online Journal Archives 1860-2000

Geography

Physics

Zusammenfassung Eine polynomische Funktion mit 8 Konstanten und eine nichtpolynomische analytische Funktion mit 6 Konstanten werden dem beobachteten mittleren Vertikalprofil des zonalen Monsun-Windes über Indien angepaßt. Die Konstanten sind auf die beobachtete Lage und Stärke des östlichen Jet Stream im oberen Niveau und des westlichen Jet Stream im unteren Niveau, auf das Niveau der Windumkehr und auf die Bodenwindgeschwindigkeit bezogen. Wenn die Konstanten realistisch gewählt werden, stimmen die analytischen Profile sehr gut mit den beobachteten Profilen im Detail überein. Ferner wird ein iteratives Schema für die Anwendung der nichtpolynomischen Representation vorgeschlagen.

Summary A polynomial function having eight constants and a non-polynomial analytical function having six constants are fitted to the observed mean vertical profile of the monsoonal zonal wind over Indian region. The constants are related to the observed position and magnitude of the upper level easterly and the lower level westerly jet streams, the level of the wind reversal and the surface wind speed. When the constants are realistically chosen, then the analytical profiles agree very well with the observed profiles, in detail. Further, an iterative scheme is suggested for improving the non-polynomial representation.

Electronic Resource