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Search Results: 1 - 10 of 401670 matches for " M. Krishnamurthy "
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Enterprise stent-within-stent embolization of a basilar artery perforator aneurysm  [PDF]
Eric M. Deshaies, Walter Jacobsen, Satish Krishnamurthy
World Journal of Neuroscience (WJNS) , 2011, DOI: 10.4236/wjns.2011.13007
Abstract: Objective and Importance—Vertebrobasilar artery aneurysms can be very challenging to treat and are preferentially dealt with using endovascular tech-niques, since they are associated with lower risk than surgical clipping. Small aneurysms located on perfo-rating arteries can pose problems though, as their dimensions may not be favorable for coiling and leave the endovascular surgeon without many options. We present a basilar perforating artery aneurysm that was successfully embolized using a stent-within-stent technique. Clinical Presentation—A 47 year old fe-male presented with a Hunt-Hess 3, Fisher Grade-3 subarachnoid hemorrhage with blood in the pre-pontine cistern. Initial imaging (CT angiogram and digital subtraction angiography) did not reveal an aneurysm. Follow-up angiography on post-bleed day eight demonstrated a three-millimeter basilar perforating artery aneurysm. After an unsuccessful coiling attempt a closed-cell stent-within-stent tech-nique was used to divert flow away from the aneu-rysm neck to induce aneurysm thrombosis. Interven-tion (or Technique)—Multiple attempts were made to access and stabilize a microcatheter in the small basilar perforator artery aneurysm in order to de-liver coils for endovascular embolization; this could not be done safely. Therefore a closed-cell 4.5 × 22 mm Enterprise stent (Cordis Neurovascular, Inc., Miami Lakes, Florida) was deployed in the basilar artery across the origin of the perforator aneurysm in order for the stent tines to divert flow away from the aneurysm neck and induce thrombosis. Persistant brisk flow within the aneurysm continued however, and a second closedcell 4.5 × 22 mm Enterprise stent was placed within the first one to increase the stent metal surface area across the aneurysm neck to further reduce flow into the aneurysm. Subsequently, angiography demonstrated stagnant blood flow in the aneurysm dome and the aneurysm spontaneously thrombosed, sparing all associated vessels. Conclu-sion—Stent-within-stent technique should be consid-ered as a possible endovascular treatment option for small side-wall and perforator artery aneurysms that can’t be safely treated with coils or embolic agents.
Low-complexity Histogram Modification Algorithm for Contrast Enhancement
V. Magudeeswaran,M. Krishnamurthy
International Journal of Computer Science and Mobile Computing , 2013,
Abstract: Histogram equalization is widely used in different waysto perform contrast enhancement in images. In this paper, a newHistogram modification algorithm is proposed for contrastenhancement of images. Histogram Equalization (HE) is one of themost popular technique used for digital image enhancement, but itis not suitable to be implemented directly in consumer electronics,such as television, because this method tends to produce an outputwith saturation effect. To overcome this weakness, Low-complexityHistogram Modification Algorithm is proposed that works well withboth video and still images, and it enhances the images withoutmaking any loss in image details.
Transport Properties of the Layer Manganite La1.5Ca1.5Mn2-xFexO7  [PDF]
M. P. Sharma, Anjali Krishnamurthy, Bipin K. Srivastava
World Journal of Condensed Matter Physics (WJCMP) , 2011, DOI: 10.4236/wjcmp.2011.14022
Abstract: Layered perovskite manganite ceramics with a nominal chemistry La1.5Ca1.5Mn2-xFexO7(x = 0.0, 0.05, 0.1, 0.3, 0.5) were prepared using sol-gel method. The manganese ions are highly mixed states of Mn3+ and Mn4+. It is found that the Mn3+/Mn4+ ratio decreases with the Fe doping content increasing. The conductivity and magnetoresistance (MR) were studied. The sample of x = 0.05 shows metal insulator transition (MIT) at 135 K. The MIT peak temperature (Tp) shifts towards higher temperature with increasing applied magnetic field. All the samples can be well fitted to the variable-range hopping (VRH) model. The maximum value of MR (%) [ρ(0) - ρ(H)]/ρ(0) × 100 for x = 0.05 is 34% (105 K, 7 kOe).
Systematic and Causal Corrections to the Coherent Potential Approximation
M. Jarrell,H. R. Krishnamurthy
Physics , 2000, DOI: 10.1103/PhysRevB.63.125102
Abstract: The Dynamical Cluster Approximation (DCA) is modified to include disorder. The DCA incorporates non-local corrections to local approximations such as the Coherent Potential Approximation (CPA) by mapping the lattice problem with disorder, and in the thermodynamic limit, to a self-consistently embedded finite-sized cluster problem. It satisfies all of the characteristics of a successful cluster approximation. It is causal, preserves the point-group and translational symmetry of the original lattice, recovers the CPA when the cluster size equals one, and becomes exact as $N_c\to\infty$. We use the DCA to study the Anderson model with binary diagonal disorder. It restores sharp features and band tailing in the density of states which reflect correlations in the local environment of each site. While the DCA does not describe the localization transition, it does describe precursor effects of localization.
Indian Streams Research Journal , 2012,
Abstract: The study was attempted to know the level of mental health of post graduate commerce subject students and their achievement in commerce subject. In this study, the investigator has used normative survey method and random sampling technique. The data was collected from 600 post graduate commerce students in various colleges from Cuddalore district. The findings of the study reveal that the post graduate commerce subject students are having above average level of mental health and average level of achievement in commerce subject. The subsamples of gender, type of institution and community shows significant difference in their mental health and achievement in commerce subject but the remaining variables under study do not show any significant difference in it. The mental health level of female students is not as much of male students, so concern authorities should give special initiative to female students to develop their mental health.
Mechanistic Studies of Antibody-Mediated Clearance of Tau Aggregates Using an ex vivo Brain Slice Model
Pavan K. Krishnamurthy,Einar M. Sigurdsson
Frontiers in Psychiatry , 2011, DOI: 10.3389/fpsyt.2011.00059
Abstract: Recent studies have shown that immunotherapy clears amyloid beta (Aβ) plaques and reduces Aβ levels in mouse models of Alzheimer’s disease (AD), as well as in AD patients. Tangle pathology is also relevant for the neurodegeneration in AD, and our studies have shown that active immunization with an AD related phospho-tau peptide reduces aggregated tau within the brain and slows the progression of tauopathy-induced behavioral impairments. Thus, clearance of neurofibrillary tangles and/or their precursors may reduce synaptic and neuronal loss associated with AD and other tauopathies. So far the mechanisms involved in antibody-mediated clearance of tau pathology are yet to be elucidated. In this study we have used a mouse brain slice model to examine the uptake and localization of FITC labeled anti-tau antibodies. Confocal microscopy analysis showed that the FITC labeled anti-tau antibody co-stained with phosphorylated tau, had a perinuclear appearance and co-localized with markers of the endosomal/lysosomal pathway. Additionally, tau and FITC–IgG were found together in an enriched lysosome fraction. In summary, antibody-mediated clearance of intracellular tau aggregates appears to occur via the lysosomal pathway.
A Parakh,S Krishnamurthy,M Bhattacharya
Kathmandu University Medical Journal , 2009, DOI: 10.3126/kumj.v7i4.2774
Abstract: Ertapenem is a parenteral carbapenem licensed for use in adults and children more than 3 months of age. It is active against many Gram-positive and negative bacteria, including several anaerobic organisms but has a narrower spectrum of antimicrobial activity, compared with older carbapenems. It is highly stable against nearly all β-lactamases, including AmpC and extended spectrum beta lactamases. Ertapenem can be given intramuscularly or intravenously and its favourable pharmacokinetic profi le allows once daily dosing. Ertapenem has been proven to be clinically and bacteriologically efficacious in randomised controlled trials for the treatment of community acquired infections including complicated intra-abdominal infections, complicated skin and skin-structure infections, acute pelvic infections, complicated urinary tract infections, community-acquired pneumonia and for the prophylaxis of surgical-site infection following elective colorectal surgery. Ertapenem is suited for mild to moderately ill patients with community-acquired infections and for outpatient intravenous antibacterial therapy. Key words: Antibiotics; Carbapenems; Ertapenem DOI: 10.3126/kumj.v7i4.2774 Kathmandu University Medical Journal (2009) Vol.7, No.4 Issue 28, 454-460
Anisotropic "charge-flipping" acceleration of highly charged ions from $(N_2)_n$ clusters in strong optical fields
M. Krishnamurthy,D. Mathur,V. Kumarappan
Physics , 2003, DOI: 10.1103/PhysRevA.69.033202
Abstract: The disassembly of molecular clusters $(N_2)_n$ ($n$=50-3000) in strong optical fields is investigated using two-dimensional time-of-flight spectrometry. Very highly charged ions are formed with a two-component energy distribution. A low-energy, isotropic component correlates with Coulomb explosion. A high-energy, anisotropic component, that results from a ``charge flipping" acceleration mechanism, gives rise to ions with energies in excess of the Coulombic limit.
Explosions of water clusters in intense laser fields
V. Kumarappan,M. Krishnamurthy,D. Mathur
Physics , 2003, DOI: 10.1103/PhysRevA.67.063207
Abstract: Energetic, highly-charged oxygen ions, $O^{q+}$ ($q\leq 6$), are copiously produced upon laser field-induced disassembly of highly-charged water clusters, $(H_2O)_n$ and $(D_2O)_n$, $n\sim$ 60, that are formed by seeding high-pressure helium or argon with water vapor. $Ar_n$ clusters (n$\sim$40000) formed under similar experimental conditions are found undergo disassembly in the Coulomb explosion regime, with the energies of $Ar^{q+}$ ions showing a $q^2$ dependence. Water clusters, which are argued to be considerably smaller in size, should also disassemble in the same regime, but the energies of fragment O$^{q+}$ ions are found to depend linearly on $q$ which, according to prevailing wisdom, ought to be a signature of hydrodynamic expansion that is expected of much larger clusters. The implication of these observations on our understanding of the two cluster explosion regimes, Coulomb explosion and hydrodynamic expansion, is discussed. Our results indicate that charge state dependences of ion energy do not constitute an unambiguous experimental signature of cluster explosion regime.
Asymmetric emission of high energy electrons in the two-dimensional hydrodynamic expansion of large xenon clusters irradiated by intense laser fields
V. Kumarappan,M. Krishnamurthy,D. Mathur
Physics , 2002, DOI: 10.1103/PhysRevA.67.043204
Abstract: Energy spectra and angular distributions have been measured of electrons that are emitted upon disassembly of $Xe_{150000}$ following irradiation by intense (10$^{15}-10^{16}$ W cm$^{-2}$) laser pulses whose durations are varied over the 100-2200 fs range. The cluster explosion dynamics occur in the hydrodynamic regime. Electron emission is found to be unexpectedly asymmetric and exhibits a resonance when the laser pulse duration is $\sim$1 ps. These results are rationalized by extending the hydrodynamic model to also take into account the force that the light field exerts on the polarization charge that is induced on surface of the cluster. We show that the magnitude of this electrostrictive force is comparable to those of Coulombic and the hydrodynamic forces, and it exhibits resonance behavior. Contrary to earlier understanding, we find that low-energy electrons are connected to the resonance in energy absorption by the cluster. The high-energy electrons seem to be produced by a mechanism that is not so strongly influenced by the resonance.
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