5,591 research outputs found
Recommended from our members
Two-fluid temperature-dependent relativistic waves in magnetized streaming pair plasmas
A relativistic two-fluid temperature-dependent approach for a streaming magnetized pair plasma is considered. Such a scenario corresponds to secondary plasmas created at the polar caps of pulsar magnetospheres. In the model the generalized vorticity rather than the magnetic field is frozen into the fluid. For parallel propagation four transverse modes are found. Two are electromagnetic plasma modes which at high temperature become light waves. The remaining two are Alfveacutenic modes split into a fast and slow mode. The slow mode is cyclotron two-stream unstable at large wavelengths and is always subluminous. We find that the instability cannot be suppressed by temperature effects in the limit of large (finite) magnetic field. The fast Alfveacuten mode can be superluminous only at large wavelengths, however it is always subluminous at high temperatures. In this incompressible approximation only the ordinary mode is present for perpendicular propagation. For oblique propagation the dispersion relation is studied for finite and large strong magnetic fields and the results are qualitatively described.Institute for Fusion Studie
Probing large distance higher dimensional gravity from lensing data
The modifications induced in the standard weak-lensing formula if Newtonian
gravity differs from inverse square law at large distances are studied. The
possibility of putting bounds on the mass of gravitons from lensing data is
explored. A bound on graviton mass, esitmated to be about 100 Mpc is
obtained from analysis of some recent data on gravitational lensing.Comment: 6 pages, 1 figure, added reference
A Case of Multiple Sclerosis Presenting as Eight and Half Syndrome.
Multiple sclerosis (MS) is a chronic disease characterized by inflammation, demyelination, gliosis (scarring), and neuronal loss; the course can be relapsing-remitting or progressive. Manifestations of MS vary from a benign illness to a rapidly evolving and incapacitating disease requiring profound lifestyle adjustments. We report a 24 year old female who presented with right internuclear ophthalmoplegia with right lower motor neuron facial nerve palsy which is called eight and half syndrome. The etiology in our patient was multiple sclerosis which was confirmed by radio-imaging studies. Patient improved on pulse therapy of methyl prednisolone and tapering dose of steroids
Detection of early osteogenic commitment in primary cells using Raman spectroscopy
Major challenges in the development of novel implant surfaces for artificial joints include osteoblast heterogeneity and the lack of a simple and sensitive in vitro assay to measure early osteogenic responses. Raman spectroscopy is a label-free, non-invasive and non-destructive vibrational fingerprinting optical technique that is increasingly being applied to detect biochemical changes in cells. In this study Raman spectroscopy has been used to obtain bone cell-specific spectral signatures and to identify any changes therein during osteoblast commitment and differentiation of primary cells in culture. Murine calvarial osteoblasts (COBs) were extracted and cultured and studied by Raman spectroscopy over a 14 day culture period. Distinct osteogenic Raman spectra were identified after 3 days of culture with strong bands detected for mineral: phosphate ν3 (1030 cm−1) and B-type carbonate (1072 cm−1), DNA (782 cm−1) and collagen matrix (CH2 deformation at 1450 cm−1) and weaker phosphate bands (948 and 970 cm−1). Early changes were detected by Raman spectroscopy compared to a standard enzymatic alkaline phosphatase (ALP) assay and gene expression analyses over this period. Proliferation of COBs was confirmed by fluorescence intensity measurements using the Picogreen dsDNA reagent. Changes in ALP levels were evident only after 14 days of culture and mRNA expression levels for ALP, Col1a1 and Sclerostin remained constant during the culture period. Sirius red staining for collagen deposition also revealed little change until day 14. In contrast Raman spectroscopy revealed the presence of amorphous calcium phosphate (945–952 cm−1) and carbonated apatite (957–962 cm−1) after only 3 days in culture and octacalcium phosphate (970 cm−1) considered a transient mineral phase, was detected after 5 days of COBs culture. PCA analysis confirmed clear separation between time-points. This study highlights the potential of Raman spectroscopy to be utilised for the early and specific detection of proliferation and differentiation changes in primary cultures of bone cells
Laser microprobe for the study of noble gases and nitrogen in single grains: a case study of individual chondrules from the Dhajala meteorite
A laser microprobe capable of analysing nitrogen and noble gases in individual grains with masses less than a milligram is described. It can be used in both continuous wave (CW) mode, useful for stepwise heating of an individual grain, as well as in pulsed mode, useful for ablating material from a small selected area of a sample, for gas extraction. We could achieve low blanks (in ccSTP units) for 4He(4.8 × 10{-12}),22Ne(1.0 × 10{-12}),36Ar(1.0 × 10 -13),84Kr(2.9 × 10{-14}),132 Xe(2.6 × 10{-14}), and N (87 pg), using this system. Preliminary data for individual chondrules from the Dhajala meteorite show that noble gases and nitrogen from grains as small as 170 microgram can be analysed using the present laser microprobe setup. The amount of trapped neon in Dhajala chondrules is very small, and nitrogen in the chondrules is isotopically heavier as compared to the bulk meteorite
Phytochemical Investigations of some Laticiferous Plants belonging to Khandesh Region of Maharashtra
Analyses were carried out on latex obtained from twenty one plant species belonging to Khandesh region of Maharashtra, India, for the presence of possible secondary metabolites, namely alkaloids, flavonoids, terpenoids, cynogenic glycosides, phenolics, tannins and saponins. Phenolic compounds were found in all latex samples except in Ipomoea carnea Jacq. Seventy six percent species of laticiferous plants contain alkaloid. Terpenoids were found in the latex of Carica papaya L. and Manilkara zapota (L.) P. van Royen only however, remaining plants were devoid. Cynogenic glycosides and tannins were detected in 52 % and 48 % of latex samples respectively. Flavonoids and saponins were detected in equal number of latex samples i.e. 38 %. Out of this, four species of Apocynaceae and single species of Euphorbiaceae, Moraceae, Carricaceae, Convolvulaceae etc. showed flavonoid. While three species of Euphorbiaceae, two species of Apocynaceae and Moraceae and single species of Asclepiadaceae showed saponin. The moisture and total solid content varies from species to species in latex samples analyzed. Euphorbia prunifolia Jacq. had highest level of moisture i.e. 93.33% and less solid content i.e. 6.67% whereas Euphorbia hirta L. had lowest level of moisture i.e.63.63% and highest content of total solid i.e. 36.37%. The results suggest that, the laticiferous plants would be exploited in the management of various diseases as they have diverse group of secondary metabolites
Systems of Linear Equations over and Problems Parameterized Above Average
In the problem Max Lin, we are given a system of linear equations
with variables over in which each equation is assigned a
positive weight and we wish to find an assignment of values to the variables
that maximizes the excess, which is the total weight of satisfied equations
minus the total weight of falsified equations. Using an algebraic approach, we
obtain a lower bound for the maximum excess.
Max Lin Above Average (Max Lin AA) is a parameterized version of Max Lin
introduced by Mahajan et al. (Proc. IWPEC'06 and J. Comput. Syst. Sci. 75,
2009). In Max Lin AA all weights are integral and we are to decide whether the
maximum excess is at least , where is the parameter.
It is not hard to see that we may assume that no two equations in have
the same left-hand side and . Using our maximum excess results,
we prove that, under these assumptions, Max Lin AA is fixed-parameter tractable
for a wide special case: for an arbitrary fixed function
.
Max -Lin AA is a special case of Max Lin AA, where each equation has at
most variables. In Max Exact -SAT AA we are given a multiset of
clauses on variables such that each clause has variables and asked
whether there is a truth assignment to the variables that satisfies at
least clauses. Using our maximum excess results, we
prove that for each fixed , Max -Lin AA and Max Exact -SAT AA can
be solved in time This improves
-time algorithms for the two problems obtained by Gutin et
al. (IWPEC 2009) and Alon et al. (SODA 2010), respectively
- …