Solar Cycle variations of ƒoF2 from IGY to 1990

Noontime monthly median values of F2-layer critical frequency ƒoF2 (m) for some ionospheric stations representing low- and mid-latitudes are examined for their dependence on solar activity for the years 1957 (IGY) to 1990. This is the period for which ionospheric data in digital form is available in two CD-ROMs at the World Data Center, Boulder. It is observed that at mid-latitudes, foF2 (m) shows nearly a linear relationship with R12 (the 12-month running average of the Zurich sunspot number), though this relation is nonlinear for low-latitudes. These results indicate some departures from the existing information often used in theoretical and applied areas of space research

Structure in Supersymmetric Yang-Mills Theory

We show that requiring sixteen supersymmetries in quantum mechanical gauge theory implies the existence of a web of constrained interactions. Contrary to conventional wisdom, these constraints extend to arbitrary orders in the momentum expansion.Comment: 22 pages, LaTe

PERFORMANCE OF SOLAR PHOTOVOLTAIC MODULE THROUGH COMBINED AIR AND WATER COOLING IN WARM AND HUMID CLIMATIC CONDITION OF INDIA

A study was conducted to evaluate the performance of solar photovoltaic module through combined air and water cooling arrangements in warm and humid climatic condition i.e. in Odisha in India during winter and summer months. Solar photovoltaic system requires neither fuel nor produces any pollutant resulting into its increased importance in today’s energy sector. The electrical output from a solar panel is a function of its efficiency and some other controlling parameters which affects the same. One of the major parameters controlling the efficiency of the panel is the temperature as it goes on increasing while using the panel in the sun. About 31 % of the incident solar radiation on the panel is converted into the useful energy and the rest part is stored in its back side causing the rise of temperature and adversely affecting its output. The stored thermal energy is of no use and decreases the durability of the in-built components of the panel due to the impact of severe thermal stresses on them resulting into reduction in its life span and conversion capability. The simplest way to enhance the efficiency of the panel is to incorporate the various cooling arrangements such as air cooling, water cooling and combined air and water cooling and assessing their effectiveness without any cooling arrangement. From the studies, it was observed that the efficiencies of solar panel were enhanced in the range of 8-11 %, 12-15% and 16-20% in air, water and combined air and water cooling respectively compared to without cooling in a clear day

DLCQ of Fivebranes, Large N Screening, and L^2 Harmonic Forms on Calabi Manifolds

We find one explicit L^2 harmonic form for every Calabi manifold. Calabi manifolds are known to arise in low energy dynamics of solitons in Yang-Mills theories, and the L^2 harmonic form corresponds to the supersymmetric ground state. As the normalizable ground state of a single U(N) instanton, it is related to the bound state of a single D0 to multiple coincident D4's in the non-commutative setting, or equivalently a unit Kaluza-Klein mode in DLCQ of fivebrane worldvolume theory. As the ground state of nonabelian massless monopoles realized around a monopole-``anti''-monopole pair, it shows how the long range force between the pair is screened in a manner reminiscent of large N behavior of quark-anti-quark potential found in AdS/CFT correspondence.Comment: LaTeX, 23 page

An HST Search for Lyman Continuum Emission From Galaxies at z=1.1--1.4

If enough of their Lyman limit continuum escapes, star-forming galaxies could be significant contributors to the cosmic background of ionizing photons. To investigate this possibility, we obtained the first deep imaging in the far ultraviolet of eleven bright blue galaxies at intermediate redshift (z=1.1--1.4). NO Lyman continuum emission was detected. Sensitive, model-independent, upper limits of typically 2 x 10**-19 erg/sec/cm2/Ang were obtained for the ionizing flux escaping from these normal galaxies. This corresponds to lower limits on the observed ratio of 1500 to 700Ang flux of 150 up to 1000. Based on a wide range of stellar synthesis models, this suggests that less than 6%, down to less than 1%, of the available ionizing flux emitted by hot stars is escaping these galaxies. The magnitude of this spectral break at the Lyman l imit confirms that the basic premise of `Lyman break' searches for galaxies at high redshift can also be applied at intermediate redshifts. This implies that the integrated contribution of galaxies to the UV cosmic background at z around 1.2 is less than 15%, and may be less than 2%.Comment: 20 manuscript pages, which includes two tables and two figures. To be published in 1 December 2003 issue of The Astrophysical Journa

11 beta-hydroxysteroid dehydrogenase type 1 regulates glucocorticoid-induced insulin resistance in skeletal muscle

OBJECTIVE: Glucocorticoid excess is characterized by increased adiposity, skeletal myopathy, and insulin resistance, but the precise molecular mechanisms are unknown. Within skeletal muscle, 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1) converts cortisone (11-dehydrocorticosterone in rodents) to active cortisol (corticosterone in rodents). We aimed to determine the mechanisms underpinning glucocorticoid-induced insulin resistance in skeletal muscle and indentify how 11beta-HSD1 inhibitors improve insulin sensitivity. \ud RESEARCH DESIGN AND METHODS: Rodent and human cell cultures, whole-tissue explants, and animal models were used to determine the impact of glucocorticoids and selective 11beta-HSD1 inhibition upon insulin signaling and action. \ud RESULTS: Dexamethasone decreased insulin-stimulated glucose uptake, decreased IRS1 mRNA and protein expression, and increased inactivating pSer$^{307}$ insulin receptor substrate (IRS)-1. 11beta-HSD1 activity and expression were observed in human and rodent myotubes and muscle explants. Activity was predominantly oxo-reductase, generating active glucocorticoid. A1 (selective 11beta-HSD1 inhibitor) abolished enzyme activity and blocked the increase in pSer$^{307}$ IRS1 and reduction in total IRS1 protein after treatment with 11DHC but not corticosterone. In C57Bl6/J mice, the selective 11beta-HSD1 inhibitor, A2, decreased fasting blood glucose levels and improved insulin sensitivity. In KK mice treated with A2, skeletal muscle pSer$^{307}$ IRS1 decreased and pThr$^{308}$ Akt/PKB increased. In addition, A2 decreased both lipogenic and lipolytic gene expression.\ud CONCLUSIONS: Prereceptor facilitation of glucocorticoid action via 11beta-HSD1 increases pSer$^{307}$ IRS1 and may be crucial in mediating insulin resistance in skeletal muscle. Selective 11beta-HSD1 inhibition decreases pSer$^{307}$ IRS1, increases pThr$^{308}$ Akt/PKB, and decreases lipogenic and lipolytic gene expression that may represent an important mechanism underpinning their insulin-sensitizing action

Molecular targets modulated by fangchinoline in tumor cells and preclinical models

© 2018 MDPI AG. All rights reserved. Despite tremendous progress made during the last few decades in the treatment options for cancer, compounds isolated from Mother Nature remain the mainstay for therapy of various malignancies. Fangchinoline, initially isolated from the dried root of Stephaniae tetrandrine, has been found to exhibit diverse pharmacological effects including significant anticancer activities both in tumor cell lines and selected preclinical models. This alkaloid appears to act by modulating the activation of various important oncogenic molecules involved in tumorigenesis leading to a significant decrease in aberrant proliferation, survival and metastasis of tumor cells. This mini-review briefly describes the potential effects of fangchinoline on important hallmarks of cancer and highlights the molecular targets modulated by this alkaloid in various tumor cell lines and preclinical models

Is there an association between vitamin D and risk of stroke?: a North Indian study

Background: Vitamin D deficiency is present in India in epidemic proportions despite plenty of sunshine. Reduced plasma 25(OH) D concentrations as a diagnostic marker of vitamin D deficiency have been in past decade associated with several well-established risk factors for ischaemic stroke, such as arterial hypertension, thrombosis, atherosclerosis. The aims and objectives of this study was to compare the serum 25(OH) D levels between the first ever acute stroke patients and healthy controls.Methods: A cross-sectional, case control study was conducted in a tertiary care hospital in New Delhi situated in north India. Serum 25‑hydroxyvitamin D (25(OH) D) levels in 85 patients of ischemic stroke, presenting within 7 days of onset of stroke was measured and was compared with 70 age and gender matched controls.Results: The mean age was 61.02±11.58 years and 58.63±11.28 years in cases and controls respectively. Females constituted 37.6% of the total number of cases and 43.4% of the controls. The age and gender-distribution were comparable between the cases and controls. The median value (IQR) of serum 25(OH) vitamin D level was 7.94 ng/mL (4.59-14.00) in the cases and it was 8.82 ng/mL (5.59-14.70) in the controls. The difference between the serum 25(OH) vitamin D levels of the two groups was not found to be statistically significant.Conclusions: There is a high prevalence of biochemical hypo-vitaminosis D in apparently healthy Indians of all age and sex groups despite adequate sunshine. There is no association between low vitamin D levels and stroke