165 research outputs found
Mass Outflow Rate From Accretion Discs around Compact Objects
We compute mass outflow rates from accretion disks around compact objects,
such as neutron stars and black holes. These computations are done using
combinations of exact transonic inflow and outflow solutions which may or may
not form standing shock waves. Assuming that the bulk of the outflow is from
the effective boundary layers of these objects, we find that the ratio of the
outflow rate and inflow rate varies anywhere from a few percent to even close
to a hundred percent (i.e., close to disk evacuation case) depending on the
initial parameters of the disk, the degree of compression of matter near the
centrifugal barrier, and the polytropic index of the flow. Our result, in
general, matches with the outflow rates obtained through a fully time-dependent
numerical simulation. In some region of the parameter space when the standing
shock does not form, our results indicate that the disk may be evacuated and
may produce quiescence states.Comment: 30 Latex pages and 13 figures. crckapb.sty; Published in Class.
Quantum Grav. Vol. 16. No. 12. Pg. 387
Slowly Varying Dilaton Cosmologies and their Field Theory Duals
We consider a deformation of the solution of IIB
supergravity obtained by taking the boundary value of the dilaton to be time
dependent. The time dependence is taken to be slowly varying on the AdS scale
thereby introducing a small parameter . The boundary dilaton has a
profile which asymptotes to a constant in the far past and future and attains a
minimum value at intermediate times. We construct the sugra solution to first
non-trivial order in , and find that it is smooth, horizon free, and
asymptotically in the far future. When the intermediate
values of the dilaton becomes small enough the curvature becomes of order the
string scale and the sugra approximation breaks down. The resulting dynamics is
analysed in the dual SU(N) gauge theory on with a time dependent coupling
constant which varies slowly. When , we find that a quantum
adiabatic approximation is applicable, and use it to argue that at late times
the geometry becomes smooth again. When ,
we formulate a classical adiabatic perturbation theory based on coherent states
which arises in the large limit. For large values of the 'tHooft coupling
this reproduces the supergravity results. For small 'tHooft coupling the
coherent state calculations become involved and we cannot reach a definite
conclusion. We argue that the final state should have a dual description which
is mostly smooth space with the possible presence of a small black
hole.Comment: LaTeX, 46 pages. Discussion in Section 6 expande
Effect of Grain Boundary Character Distribution on the Impact Toughness of 410NiMo Weld Metal
Grain boundary character distributions in 410NiMo weld metal were studied in the as-welded, first-stage, and second-stage postweld heat treatment (PWHT) conditions, and these were correlated with the Charpy-V impact toughness values of the material. The high impact toughness values in the weld metal in the as-welded and first-stage PWHT conditions compared to that in the second-stage condition are attributed to the higher fraction of low-energy I pound boundaries. A higher volume fraction of retained austenite and coarser martensite after second-stage PWHT accompanied by the formation of the ideal cube component in the 2-hour heat-treated specimen led to a reduction in the toughness value. A subsequent increase in the PWHT duration at 873 K (600 A degrees C) enhanced the formation of {111}aOE (c) 112 >, which impedes the adverse effect of the cubic component, resulting in an increase in the impact toughness. In addition to this, grain refinement during 4-hour PWHT in the second stage also increased the toughness of the weld metal
An integrated organic farming system: innovations for farm diversification, sustainability, and livelihood improvement of hill farmers
IntroductionOrganic farming is a promising solution for mitigating environmental burdens related to input-intensive agricultural practices. The major challenge in organic agriculture is the non-availability of large quantities of organic inputs required for crop nutrition and sustaining soil health, which can be resolved by efficient recycling of the available on- and off-farm resources and the integration of the components as per the specific locations.MethodsAn integrated organic farming system (IOFS) model comprising agricultural and horticultural crops, rainwater harvesting units, livestock components, and provisions for nutrient recycling was developed and disseminated in the adopted organic villages Mynsain, Pynthor, and Umden Umbathiang in the Ri-Bhoi District, Meghalaya, India, to improve the income and livelihood of farmers. Harvested rainwater in farm ponds and Jalkunds was used for live-saving irrigation in the winter months and diversified homestead farming activities, such as growing high-value crops and rearing cattle, pigs, and poultry.ResultsMaize, french bean, potato, ginger, tomato, carrot, and chili yields in the IOFS model increased by 20%−30%, 40%−45%, 25%−30%, 33%−40%, 45%−50%, 37%−50%, and 27%−30%, respectively, compared with traditional practices. Some farmers produced vermicompost in vermibeds (made of high-density polyethylene) and cement brick chambers, generating 0.4−1.25 tons per annum. Two individual farmers, Mr. Jrill Makroh and Mrs. Skola Kurbah obtained net returns (without premium price) of Rs. 46,695 ± 418 and Rs. 31,102 ± 501 from their respective 0.27- and 0.21-ha IOFS models, which is equivalent to Rs. 172,944 ± 1,548/ha/year and Rs. 148,105 ± 2,385/ha/year, respectively. The net returns obtained from the IOFS models were significantly higher than those obtained from the farmers' practice of maize-fallow or cultivation of maize followed by vegetable (~30% of the areas). It is expected that, with the certification of organic products, the income and livelihood of the farmers will improve further over the years. While Mr. Jrill Makroh's model supplied 95.1%, 82.0%, and 96.0% of the total N, P2O5, and K2O, respectively, needed by the system, Mrs. Skola Kurbah's model supplied 76.0%, 68.6%, and 85.5% of the total N, P2O5, and K2O, respectively.DiscussionThus, IOFS models should be promoted among hill farmers so that they can efficiently recycle farm resources and increase their productivity, net returns, and livelihood while reducing their dependence on external farm inputs
3, 3′5 Triiodo L Thyronine Induces Apoptosis in Human Breast Cancer MCF-7cells, Repressing SMP30 Expression through Negative Thyroid Response Elements
Thyroid hormones regulate cell proliferation, differentiation as well as apoptosis. However molecular mechanism underlying apoptosis as a result of thyroid hormone signaling is poorly understood. The antiapoptotic role of Senescence Marker Protein-30 (SMP30) has been characterized in response to varieties of stimuli as well as in knock out model. Our earlier data suggest that thyroid hormone 3, 3'5 Triiodo L Thyronine (T(3)), represses SMP30 in rat liver.In highly metastatic MCF-7, human breast cancer cell line T3 treatment repressed SMP30 expression leading to enhanced apoptosis. Analysis by flow cytometry and other techniques revealed that overexpression and silencing of SMP30 in MCF-7 resulted in decelerated and accelerated apoptosis respectively. In order to identify the cis-acting elements involved in this regulation, we have analyzed hormone responsiveness of transiently transfected hSMP30 promoter deletion reporter vectors in MCF-7 cells. As opposed to the expected epigenetic outcome, thyroid hormone down regulated hSMP30 promoter activity despite enhanced recruitment of acetylated H3 on thyroid response elements (TREs). From the stand point of established epigenetic concept we have categorised these two TREs as negative response elements. Our attempt of siRNA mediated silencing of TRβ, reduced the fold of repression of SMP30 gene expression. In presence of thyroid hormone, Trichostatin- A (TSA), which is a Histone deacetylase (HDAC) inhibitor further inhibited SMP30 promoter activity. The above findings are in support of categorisation of both the thyroid response element as negative response elements as usually TSA should have reversed the repressions.This is the first report of novel mechanistic insights into the remarkable downregulation of SMP30 gene expression by thyroid hormone which in turn induces apoptosis in MCF-7 human breast cancer cells. We believe that our study represents a good ground for future effort to develop new therapeutic approaches to challenge the progression of breast cancer
Finding Our Way through Phenotypes
Despite a large and multifaceted effort to understand the vast landscape of phenotypic data, their current form inhibits productive data analysis. The lack of a community-wide, consensus-based, human- and machine-interpretable language for describing phenotypes and their genomic and environmental contexts is perhaps the most pressing scientific bottleneck to integration across many key fields in biology, including genomics, systems biology, development, medicine, evolution, ecology, and systematics. Here we survey the current phenomics landscape, including data resources and handling, and the progress that has been made to accurately capture relevant data descriptions for phenotypes. We present an example of the kind of integration across domains that computable phenotypes would enable, and we call upon the broader biology community, publishers, and relevant funding agencies to support efforts to surmount today's data barriers and facilitate analytical reproducibility
A Landau-Squire nanojet
Fluid jets are found in nature at all length scales, from microscopic to
cosmological. Here we report on an electroosmotically driven jet from a single
glass nanopore about 75 nm in radius with a maximum flow rate ~15 pL/s. A novel
anemometry technique allows us to map out the vorticity and velocity fields
that show excellent agreement with the classical Landau-Squire solution of the
Navier Stokes equations for a point jet. We observe a phenomenon that we call
flow rectification: an asymmetry in the flow rate with respect to voltage
reversal. Such a nanojet could potentially find applications in
micromanipulation, nanopatterning, and as a diode in microfluidic circuits.Comment: 20 pages, 4 figure
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