Revised Results for Non-thermal Recombination Flare Hard X-Ray Emission

Brown and Mallik (BM) recently showed that, for hot sources, recombination of non-thermal electrons (NTR) onto highly ionised heavy ions is not negligible compared to non-thermal bremsstrahlung (NTB) as a source of flare hard X-rays (HXRs) and so should be included in modelling non-thermal HXR flare emission. In view of major discrepancies between BM results for the THERMAL continua and those of the Chianti code and of RHESSI solar data, we critically re-examine and correct the BM analysis and modify the conclusions concerning the importance of NTR. Although the analytic Kramers expression used by BM is correct for the purely hydrogenic recombination cross section, the heuristic expressions used by BM to extend the Kramers expression beyond the `bare nucleus' case to which it applies had serious errors. BM results have therefore been recalculated using corrected expressions, which have been validated against the results of detailed calculations. At T ~ 10-30 MK the dominant ions are Fe 22+, 23+, 24+ for which BM erroneously overestimated NTR emission by around an order of magnitude. Contrary to the BM claim, NTR in hot flare plasmas does NOT dominate over NTB, although in some cases it can be comparable and so still very important in inversions of photon spectra to derive electron spectra, especially as NTR includes sharp edge features. The BM claim of dominance of NTR over NTB in deka-keV emission is incorrect due to a serious error in their analysis. However, the NTR contribution can still be large enough to demand inclusion in spectral fitting, the spectral edges having potentially serious effects on inversion of HXR spectra to infer fast electron spectra.Comment: 6 pages, 8 figures, 1 tabl

XXVI. Dynamical theory of diffraction

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Magnetic behaviour of Eu_2CuSi_3: Large negative magnetoresistance above Curie temperature

We report here the results of magnetic susceptibility, electrical-resistivity, magnetoresistance (MR), heat-capacity and ^{151}Eu Mossbauer effect measurements on the compound, Eu_2CuSi_3, crystallizing in an AlB_2-derived hexagonal structure. The results establish that Eu ions are divalent, undergoing long-range ferromagnetic-ordering below (T_C=) 37 K. An interesting observation is that the sign of MR is negative even at temperatures close to 3T_C, with increasing magnitude with decreasing temperature exhibiting a peak at T_C. This observation, being made for a Cu containing magnetic rare-earth compound for the first time, is of relevance to the field of collosal magnetoresistance.Comment: To appear in PRB, RevTex, 4 pages text + 6 psFigs. Related to our earlier work on Gd systems (see cond-mat/9811382, cond-mat/9811387, cond-mat/9812069, cond-mat/9812365

Experimental investigation of the response of a harmonically excited hard Duffing oscillator

A single degree-of-freedom torsional vibratory system, which constitutes a third-order dissipative dynamical system, has been fabricated as a mechanical analogue of hard Duffing equation with strong nonlinearity. The forced response of the system reveals complicated and chaotic motion at low frequency regime. Besides usual jump phenomenon, unpredictable jump phenomenon with two and three coexisting periodic attractors is also observed

Correlation of cancer treatment related fatigue with biochemical & hormonal profile a prospective study

Background: Cancer treatment using chemotherapy or radiotherapy results in considerable cancer treatment related fatigue. Fatigue can induce significant stress causing hormonal alteration through hypothalamic pituitary axis leading to change in the internal milieu. We evaluated hormonal and biochemical profile to find out a putative corr~lation. Materials & Method: Fifty two histopathology documented cases of cancer patients were subjected to Pipers Fatigue Score (PFS) and blood test for hormone and other biochemical parameters before and after radiotherapy and chemotherapy treatment. Human growth hormone, adenocorticotrophic hormone, thyroid stimulating hormone and serum free cortisol level were evaluated along with routine biochemical analysis before and after anticancer treatment. The individual fatigue score were compared with individual hormone levels and other biochemical parameters. Results: Fifty two cancer patients planned for anticancer therapy completed initial pretreatment evaluation however post treatment assessment was not possible in 8 cases as they died during therapy. There were 20 males and 32 females in the study with a median age of 50 years (range15-78 years). The stage distribution was as stage-1 (12°k), stage-11 (17°.4>), stage-Ill (44%) and stage-IV (26°/o).The primary cancer were in breast (19°/o), sarcomas (9°/o), head and neck (19°k), gynecological (19°/o) and miscellaneous sites (14o/o). The individual fatigue score were behavioral severity (26.6°.4>), affective meaning (28°/o), sensory (22.2%), cognitive mood (8.8%) and total score (22.2°.4>) respectively. There were significant rise in the fatigue score followi~g chemotherapy and radiotherapy. The serum human growth hormone and cortisol were positively correlated whereas serum TSH level was negatively correlated with fatigue. Conclusions: Cancer treatment related fatigue is a multidimensional event that affect stress hormonal ·milieu. The human growth hormone and corticotrophins were affected among cancer patients suffering from cancer treatment related fatigue. Probably this finding may help to improve therapeutic intervention in the management fatigue in cance

Stochastic modeling of cargo transport by teams of molecular motors

Many different types of cellular cargos are transported bidirectionally along microtubules by teams of molecular motors. The motion of this cargo-motors system has been experimentally characterized in vivo as processive with rather persistent directionality. Different theoretical approaches have been suggested in order to explore the origin of this kind of motion. An effective theoretical approach, introduced by M\"uller et al., describes the cargo dynamics as a tug-of-war between different kinds of motors. An alternative approach has been suggested recently by Kunwar et al., who considered the coupling between motor and cargo in more detail. Based on this framework we introduce a model considering single motor positions which we propagate in continuous time. Furthermore, we analyze the possible influence of the discrete time update schemes used in previous publications on the system's dynamic.Comment: Cenference proceedings - Traffic and Granular Flow 1

Isolation, genetic diversity and identification of a virulent pathogen of eriophyid mite, Aceria guerreronis (Acari: Eriophyidae) by DNA marker in Karnataka, India

Aceria guerreronis is a serious pest of coconut in India. Investigations were carried out to investigate fungal pathogens infecting the eriophyid mites for their utilisation as biocontrol agents in Karnataka, India. The fungal pathogens namely, Hirsutella thompsonii, Beauveria bassiana, Fusarium semitectum and few opportunistic pathogens namely, Fusarium moniliforme, Cladosporium tennuissimum, Aspergillus niger, Penicillium sp. and Mucor sp. were collected from eriophyid mite populations in different parts of Karnataka area. Of the total collected nuts, 3.54% were infected by H. thompsonii, 2.46 and 0.29% by B. bassiana and F. semitectum, respectively. A lower number of nuts (0.03 to 0.79%) were infected by opportunistic pathogens. The incidence of pathogen infected coconuts in areas with lower temperature and higher humidity were ranged from 4.37 to 19.52% whereas with higher temperature and lower humidity it was 0 to 4.54%. Occurrence of B. bassiana and F. semitectum on A. guerreronis are new records. Among isolates of H. thompsonii collected from different places, the isolate Bangalore was more virulent followed by Mysore, Mandya, Kanakapura, Arsikere and Hiriyur isolates, as it recorded maximum infection (HTCMBAN- 88.63%). The B. bassiana isolates caused mortality ranging from 72.87 to 86.97%. The virulent isolate H. thompsonii (HTCMBAN) was tested at different concentrations, with increase in the concentration mortality rate. The genetic diversity of isolates of H. thompsonii by random amplification of polymorphic DNA (RAPD) revealed that grouping of the isolates was in accordance with geographic location. DNA fragments of 850 and 950 bp (OPA-20) were specific to the virulent isolate HTCMBAN.Key words: Fungal pathogens, eriophyid mites, genetic diversity, DNA marker