2,981 research outputs found
Localization Transition of Biased Random Walks on Random Networks
We study random walks on large random graphs that are biased towards a
randomly chosen but fixed target node. We show that a critical bias strength
b_c exists such that most walks find the target within a finite time when
b>b_c. For b<b_c, a finite fraction of walks drifts off to infinity before
hitting the target. The phase transition at b=b_c is second order, but finite
size behavior is complex and does not obey the usual finite size scaling
ansatz. By extending rigorous results for biased walks on Galton-Watson trees,
we give the exact analytical value for b_c and verify it by large scale
simulations.Comment: 4 pages, includes 4 figure
Performance of Improved Forage Species under Dry Temperate Conditions of North Western Himalayas
The dry temperate region of Himalayas is characterized by low precipitation, low temperature and high snowfall. In this region generally, all the areas excluding the intensively cultivated one are used as pasture and grasslands. The area is characterized by sloppy desert mountains with crop growing season of 5-6 months (April to September). In the region due to continuous heavy grazing and lack of management indigenous grass species presently represent the third or fourth stage of degradation. In north western Himalayas livestock plays a significant role in sustaining the livelihood of people, but in the region all forage resources are hardly enough to meet the forage requirement of even 40-50 per cent of the existing livestock population. Under this situation the planting of ecologically adaptable improved grasses and forage legumes appears to be a viable preposition to increase the forage production and availability in the region. Keeping in view this, the present study was undertaken to study the comparative performance of improved grasses and legume species under dry temperate climatic conditions
Multimodal Magnetic Resonance and Near-Infrared-Fluorescent Imaging of Intraperitoneal Ovarian Cancer Using a Dual-Mode-Dual-Gadolinium Liposomal Contrast Agent.
The degree of tumor removal at surgery is a major factor in predicting outcome for ovarian cancer. A single multimodality agent that can be used with magnetic resonance (MR) for staging and pre-surgical planning, and with optical imaging to aid surgical removal of tumors, would present a new paradigm for ovarian cancer. We assessed whether a dual-mode, dual-Gadolinium (DM-Dual-Gd-ICG) contrast agent can be used to visualize ovarian tumors in the peritoneal cavity by multimodal MR and near infra-red imaging (NIR). Intraperitoneal ovarian tumors (Hey-A8 or OVCAR3) in mice enhanced on MR two days after intravenous DM-Dual Gd-ICG injection compared to controls (SNR, CNR, p < 0.05, n = 6). As seen on open abdomen and excised tumors views and confirmed by optical radiant efficiency measurement, Hey-A8 or OVCAR3 tumors from animals injected with DM-Dual Gd-ICG had increased fluorescence (p < 0.05, n = 6). This suggests clinical potential to localize ovarian tumors by MR for staging and surgical planning, and, by NIR at surgery for resection
Reentrant phase transition in charged colloidal suspensions
We report the observation of a novel phase transition in dilute aqueous suspensions of polystyrene particles as a function of ionic impurity concentration C. The suspension phase separates into dense and rare phases only for a restricted range of C which depends on particle concentration n. The dense phase has liquidlike or crystalline order depending on n and C. Free energies of the homogeneous and the phase-separated states are calculated with an effective interparticle potential. The calculated phase diagram is in qualitative agreement with the present experimental results
Low temperature and high pressure Raman and x-ray studies of pyrochlore TbTiO : phonon anomalies and possible phase transition
We have carried out temperature and pressure-dependent Raman and x-ray
measurements on single crystals of TbTiO. We attribute the observed
anomalous temperature dependence of phonons to phonon-phonon anharmonic
interactions. The quasiharmonic and anharmonic contributions to the
temperature-dependent changes in phonon frequencies are estimated
quantitatively using mode Gr\"{u}neisen parameters derived from
pressure-dependent Raman experiments and bulk modulus from high pressure x-ray
measurements. Further, our Raman and x-ray data suggest a subtle structural
deformation of the pyrochlore lattice at 9 GPa. We discuss possible
implications of our results on the spin-liquid behaviour of TbTiO.Comment: 10 figures, 26 pages. Appeared in Physical Review B, vol-79,
pp-134112 (2009
Morphometric analysis of Dactylorhiza hatagirea (D. Don), a critically endangered orchid in cold desert Ladakh region of India
The morphometric study was conducted during 2009 to 2010. About 28 morphological characters were measured under 13 natural populations of Dactylorhiza hatagirea. Geographic variation in morphology reflects phenotypic responses to environmental gradients and evolutionary history of populations and species. At points, beside its broad geographic range (Nubra, Suru and Indus valley) characterization of Dactylorhiza phenotype is normally accomplished by use of morphological descriptors, hence as a first step, phenotype collection and its morphometric analysis was assessed. However, plant height, leaf length, lowermost leaf length, length of second leaf from base and mean length from lowest bract to the top of inflorescence are presented to account for the remarkable variation in morphological characters. Tirith population showed more values of this trait while Skurru showed less value. From this, it is concluded that Tirith showed great morphometric variation as compared to other population. Multivariate morphometric techniques, principal component analysis (PCA), multidimensional scaling (MDS) and cluster analysis were used to determine whether these populations can be reliably morphologically similar or dissimilar. The first two principal components encompass more than 75% variation among population. The results of PCA and MDS analysis were comparable to the cluster analysis, which shows considerable phenotypic variation in morphological and horticultural traits that can be utilized in its genetic improvement. To support this study, further constructive information were provided on the status of the populations of D. hatagirea which may increase the conservation value of this site and resolve the suitable areas with taxonomic and nomenclatural controversies.Keywords: Morphological characters, principal component analysis (PCA), multidimensional scaling (MDS), plant height, leaf length, leaf widt
Ultrafast electron dynamics and cubic optical nonlinearity of free standing thin film of double walled carbon nanotubes
Ultrafast degenerate pump-probe experiments performed on a free standing film
of double walled carbon nanotubes near the first metallic transition energy of
outer tube show ultrafast () photobleaching followed by a photo-induced
absorption with a slow relaxation of . Femtosecond closed and open
aperture z-scan experiments carried out at the same excitation energy show
saturation absorption and negative cubic nonlinearity. From these measurements,
real and imaginary part of the third order nonlinear susceptibility are
estimated to be Re( and
Im(.Comment: 8 pages, 3 figure
Temperature dependent Raman and x-ray studies of spin-ice pyrochlore and non-magnetic pyrochlore
We present here temperature-dependent Raman, x-ray diffraction and specific
heat studies between room temperature and 12 K on single crystals of spin-ice
pyrochlore compound and its non-magnetic analogue .
Raman data show a "new" band not predicted by factor group analysis of
Raman-active modes for the pyrochlore structure in , appearing
below a temperature of 110 K with a concomitant contraction of the cubic
unit cell volume as determined from the powder x-ray diffraction analysis. Low
temperature Raman experiments on O-isotope substituted
confirm the phonon origin of the "new" mode. These findings, absent in
, suggest that the room temperature cubic lattice of the
pyrochlore undergoes a "subtle" structural transformation near
. We find anomalous \textit{red-shift} of some of the phonon modes in both
the and the as the temperature decreases, which is
attributed to strong phonon-phonon anharmonic interactions.Comment: 28 pages, 9 figures (Accepted for publication in Physical Review B
The Pharmacological Activities of the Metabolites of N-[(Trimethylamineboryl)-Carbonyl]-L-Phenylalanine Methyl Ester
The metabolites of N-[(trimethylamineboryl)-carbonyl]-L-phenylalanine methyl ester 1
proved to be active in a number of pharmacological screens where the parent had previously demonstrated potent activity. The proposed metabolites demonstrated significant activity as
cytotoxic, hypolipidemic, and anti-inflammatory agents. In cytotoxicity screens several of the
proposed metabolites afforded better activity than the parent compound against the growth of
suspended and solid tumor cell lines. Evaluation of in vivo hypolipidemic activity demonstrated
that the proposed metabolites of 1 were only moderately active and were generally less effective
than the parent compound. Interestingly, L-phenylalanine methyl ester hydrochloride 3, which
contains no boron atom, demonstrated equivalent hypolipidemic activity as the parent at 8
mg/kg/day in CF1 male mice. As anti-inflammatory agents the proposed metabolites
demonstrated variable capacities to reduce foot pad inflammation. These compounds were
similarly effective as the parent 1 at blocking local pain and were generally better than the parent
at protecting CF1 male mice from LPS induced sepsis
First presentation of LPIN1 acute rhabdomyolysis in adolescence and adulthood
LPIN1 mutations are a known common cause of autosomal recessive, recurrent and life-threatening acute rhabdomyolysis of childhood-onset. The first episode of rhabdomyolysis usually happens in nearly all cases before the age of 5 and death is observed in 1/3 of patients. Here we present two cases of acute rhabdomyolysis with a milder phenotype caused by LPIN1 mutation presenting in adolescence (11 years old) and adulthood (40 years old) after Parvovirus infection and metabolic stress, respectively. In our opinion, the mutation types, epigenetic factors, the environment exposition to triggers or the existence of proteins with a similar structure of LPIN1, may have a role in modulating the onset of rhabdomyolysis. LPIN1 should be included on a panel of genes analysed in the investigation of adult individuals with rhabdomyolysis. Metabolic and viral stressors should be included in the list of possible rhabdomyolysis precipitant
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