ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Anomalous width variations for ion acoustic rarefactive solitary waves in a warm ion plasma with two electron temperatures (1997)

Ghosh, S. S. ; Sekar Iyengar, A. N.

[S.l.] : American Institute of Physics (AIP)

Physics of Plasmas 4 (1997), S. 3204-3210

add to mindlist on the mindlist

Details

ISSN: 1089-7674

Source: AIP Digital Archive

Topics: Physics

Notes: Anomalous width–amplitude variations were observed in large amplitude rarefactive solitary waves which show increasing width with increasing amplitude, contrasting the usual reciprocal relation between the square of the width and the amplitude, beyond a certain value of the plasma parameters [S. S. Ghosh, K. K. Ghosh, and A. N. Sekar Iyengar, Phys. Plasmas, 3, 3939 (1996)]. For the limiting maximum amplitude, the "increasing width" solitary wave tends to a double layer-like solution. The overall variation was found to depend crucially on the specific parameter space. From a detailed investigation of the above behavior, a plausible physical explanation has been presented for such increases in the width. It is found that the ions' initial kinetic energies and the cold electron concentration within the perturbed region play a significant role in determining the observed width–amplitude variation. This contradicts the investigation of Sayal, Yadav, and Sharma [Phys. Scr. 47, 576 (1993)]. © 1997 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.872461

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

2

Electronic Resource

Forbidden regions in ion temperatures for ion acoustic compressive solitary waves for a plasma with two electron temperatures (1997)

Ghosh, S. S. ; Sekar Iyengar, A. N.

[S.l.] : American Institute of Physics (AIP)

Physics of Plasmas 4 (1997), S. 2139-2145

add to mindlist on the mindlist

Details

ISSN: 1089-7674

Source: AIP Digital Archive

Topics: Physics

Notes: It is observed that, there exist certain forbidden regions in ion temperatures, for a compressive solitary wave, which do not have any solitary wave solution. These regions exist for a two- as well as a single-electron temperature plasma. A physical model is proposed to explain this phenomenon on the basis of the energy relation. It is revealed that a one-dimensional single warm ion fluid consists of two distinct energy components. A simple algebraic condition has been derived which expresses the balance between nonlinearity and dispersion for a fully nonlinear solitary wave. It shows that both the nonlinearity and dispersion decrease with increasing ion temperature and that the balance condition is well maintained for the whole spectrum of solitary wave solutions. © 1997 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.872378

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

3

Electronic Resource

Nonlinear entropy production operators for magnetohydrodynamic plasmas (1995)

Siregar, E. ; Ghosh, S. ; Goldstein, M. L.

[S.l.] : American Institute of Physics (AIP)

Physics of Plasmas 2 (1995), S. 1480-1493

add to mindlist on the mindlist

Details

ISSN: 1089-7674

Source: AIP Digital Archive

Topics: Physics

Notes: A method for constructing closure relations based on the invariants of the tensors representing nonequilibrium thermodynamic forcing within the plasma is presented. This approach leads to closure relations that describe all higher-order forcing effects contained within the continuum description. Nonlinear convective-momentum transport and nonlinear momentum-exchange operators are constructed as applications of the method. Closure is achieved by relating the pressure tensor to invariants of the rate of strain tensor, and the momentum-exchange operator to invariants of the gradient of magnetic field tensor. These operators lead to positive definite viscous and Joule entropy production and enhance high wave number dissipative couplings over all other dissipative couplings. The nonlinear dissipative action is localized in physical space, where velocity and magnetic gradients are large, while allowing nearly ideal behavior elsewhere. The operators are computationally tested against the standard magnetohydrodynamic (MHD) operators using three-dimensional configurations that lead to vortex street formation and magnetic reconnection. The nonlinear operators allow greater spatial structure and have flatter modal energy spectra than the standard MHD dissipation operators. Closures that describe the plasma response to nonequilibrium thermodynamic forcing of all orders can be constructed using this approach. © 1995 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.871363

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

4

Electronic Resource

Large Mach number ion acoustic rarefactive solitary waves for a two electron temperature warm ion plasma (1996)

Ghosh, S. S. ; Ghosh, K. K. ; Sekar Iyengar, A. N.

[S.l.] : American Institute of Physics (AIP)

Physics of Plasmas 3 (1996), S. 3939-3946

add to mindlist on the mindlist

Details

ISSN: 1089-7674

Source: AIP Digital Archive

Topics: Physics

Notes: An exact analytical form of Sagdeev pseudopotential has been derived for a two electron temperature warm ion plasma, from which ion acoustic rarefactive solitary wave solutions could be investigated for a wide range of different plasma parameters, viz., ion temperature (σ), cold to hot electron temperature ratio (β), and initial cold electron concentration (μ). Explicitly large Mach numbers have been obtained for increasing hot to cold electron temperature ratios, and an analytical condition for the upper bound of the Mach number has been derived for such a rarefactive solitary wave. It is found that the width of these waves obey Korteweg–de Vries soliton-type behavior only for small amplitudes (i.e., eφ/Teff〈1) while for large amplitudes, the width of the rarefactive solitary waves increases with increasing amplitude. © 1996 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.871567

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

5

Electronic Resource

Interference effects in photoreflectance and contactless electroreflectance spectra of CdTe films grown on Si substrate (1997)

Ghosh, S. ; Arora, B. M.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 81 (1997), S. 6968-6974

add to mindlist on the mindlist

Details

ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: We report the observation of oscillatory features (OFs) in the photoreflectance (PR) and contactless electroreflectance (CER) spectra of CdTe films grown on Si substrate, at energies below the band gap of CdTe. The simultaneous observation of OF in the reflectance (R) spectrum having the same period as those in the PR and CER spectra (as also their dependence on film thickness) provides a direct proof for optical interference effects as being the source of these features. However, in the present case the amplitude of the OF gets damped towards shorter wavelengths while remaining nearly wavelength independent in the longer wavelength region indicating a modulation mechanism different from those reported earlier. A series of experiments and simulations performed by us seem to indicate that while in PR the principal mechanism is the pump beam induced periodic temperature changes which in turn modulates the optical path length of the CdTe film, in CER the mechanism is the electric field induced modulation of the subband gap refractive index of the film through the electro-optic effect. The damping of the OF has been explained on the basis of subband gap absorption by the CdTe film. © 1997 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.365260

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

6

Electronic Resource

Strong photoluminescence in ammonia plasma treated amorphous-SiC thin films deposited by laser ablation (1996)

Ghosh, S. ; Bhattacharya, P. ; Bose, D. N.

Woodbury, NY : American Institute of Physics (AIP)

Applied Physics Letters 68 (1996), S. 2979-2981

add to mindlist on the mindlist

Details

ISSN: 1077-3118

Source: AIP Digital Archive

Topics: Physics

Notes: Amorphous-SiC films have been deposited by pulsed laser ablation on silicon substrates. Photoluminescence (PL) studies showed two broad bands with peaks at 1.34 and 1.72 eV for these unhydrogenated films. On NH3 passivation the intensity of the 1.34 eV peak increased by a large factor of 40–50 with full width at half-maximum (FWHM) decreasing to 13.5 meV at 12 K. The activation energy of this level was found to be 24 meV. These results are in contrast with those from unhydrogenated a-Si. A possible mechanism responsible for PL enhancement is discussed. © 1996 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.116670

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

Paper (German National Licenses)

Fulltext

7

Unknown

Human platelet signaling defect characterized by impaired production of inositol-1,4,5-triphosphate and phosphatidic acid and diminished Pleckstrin phosphorylation: evidence for defective phospholipase C activation (1996)

Yang, X ; Sun, L ; Ghosh, S ; [et al.]

American Society of Hematology

In: Blood. 1996; 88(5): 1676-1683. Published 1996 Sep 01. doi: 10.1182/blood.v88.5.1676.bloodjournal8851676.

add to mindlist on the mindlist

Details

Publication Date: 1996-09-01

Description: Signal transduction on platelet activation involves phosphoinositide- specific phospholipase C (PLC)-mediated hydrolysis of phosphatidylinositides and formation of inositol-1,4,5-triphosphate [I(1,4,5)P3], which mediates Ca2+ mobilization, and diacylglycerol (DG), which activates protein kinase C (PKC) to phosphorylate a 47-kD protein (Pleckstrin). We studied these events in two related patients previously reported (Blood 74:664, 1989) to have abnormal aggregation and 14C-serotonin secretion, and impaired intracellular Ca2+ mobilization in response to several agonists. Thrombin-induced I(1,4,5)P3 and phosphatidic acid formation were diminished. Pleckstrin phosphorylation was impaired on activation with thrombin, platelet- activating factor, and ionophore A23187, but was normal with PKC activator 1,2-dioctonyl-sn-glycerol (DiC8). Ca2+ mobilization induced by guanosine triphosphate (GTP) analog guanosine 5′-0-(3 thiotriphosphate) (GTP gamma S) was diminished. Pretreatment with either A23187 or DiC8 did not correct the impaired adenine diphosphate- induced secretion; however, upon stimulation with A23187 plus DiC8, pleckstrin phosphorylation and secretion were normal, indicating that both PKC activation and Ca2+ mobilization are essential for normal secretion. We conclude that these patients have a unique inherited platelet defect in formation of two key intracellular mediators [I(1,4,5)P3 and DG] and in the responses mediated by them due to a defect in postreceptor mechanisms of PLC activation.

Print ISSN: 0006-4971

Electronic ISSN: 1528-0020

Topics: Biology , Medicine

Published by American Society of Hematology

Permalink

	Location	Call Number	Expected	Availability

Others were also interested in ...

PAPER CURRENT

S·F·X

Fulltext

8

Unknown

Human platelet signaling defect characterized by impaired production of inositol-1,4,5-triphosphate and phosphatidic acid and diminished Pleckstrin phosphorylation: evidence for defective phospholipase C activation (1996)

Yang, X ; Sun, L ; Ghosh, S ; [et al.]

American Society of Hematology

In: Blood. 1996; 88(5): 1676-1683. Published 1996 Sep 01. doi: 10.1182/blood.v88.5.1676.1676.

add to mindlist on the mindlist

Details

Publication Date: 1996-09-01

Description: Signal transduction on platelet activation involves phosphoinositide- specific phospholipase C (PLC)-mediated hydrolysis of phosphatidylinositides and formation of inositol-1,4,5-triphosphate [I(1,4,5)P3], which mediates Ca2+ mobilization, and diacylglycerol (DG), which activates protein kinase C (PKC) to phosphorylate a 47-kD protein (Pleckstrin). We studied these events in two related patients previously reported (Blood 74:664, 1989) to have abnormal aggregation and 14C-serotonin secretion, and impaired intracellular Ca2+ mobilization in response to several agonists. Thrombin-induced I(1,4,5)P3 and phosphatidic acid formation were diminished. Pleckstrin phosphorylation was impaired on activation with thrombin, platelet- activating factor, and ionophore A23187, but was normal with PKC activator 1,2-dioctonyl-sn-glycerol (DiC8). Ca2+ mobilization induced by guanosine triphosphate (GTP) analog guanosine 5′-0-(3 thiotriphosphate) (GTP gamma S) was diminished. Pretreatment with either A23187 or DiC8 did not correct the impaired adenine diphosphate- induced secretion; however, upon stimulation with A23187 plus DiC8, pleckstrin phosphorylation and secretion were normal, indicating that both PKC activation and Ca2+ mobilization are essential for normal secretion. We conclude that these patients have a unique inherited platelet defect in formation of two key intracellular mediators [I(1,4,5)P3 and DG] and in the responses mediated by them due to a defect in postreceptor mechanisms of PLC activation.

Print ISSN: 0006-4971

Electronic ISSN: 1528-0020

Topics: Biology , Medicine