3,252 research outputs found
Bone histomorphometric study of young rats following oestrogen deficiency
Osteoporosis is a global problem which results in increased fractures risk. The reports from earlier studies were inconsistent with the aging factor as well as the time which is needed to induce bone loss post-ovariectomy. This study aimed to determine the short-term effects of estrogen deficiency on bone structural histomorphometric parameters in young rats. 30 Sprague-Dawley female rats weighing 250 to 300 g were assigned to baseline, sham-operated and ovariectomy groups. The baseline group (n = 10) was sacrificed immediately. Sham-operated rats (SO, n = 10) underwent sham operation while ovariectomised group (OVX, n =10) underwent bilateral ovariectomy. All the rats were sacrificed 6 weeks post-ovariectomy. Following sacrifice, the right femora were dissected and subjected to the histomorphometric analysis using modified Von Kossa method. Bone volume/tissue volume (BV/TV) and trabecular number (Tb.N) reduced significantly, while trabecular separation (Tb.Sp) increased significantly in the ovariectomized rats, compared to the baseline and sham groups 6 weeks postovariectomy (P<0.001). In the other hand, trabecular thickness (Tb.Th) was consistent among the groups (P=0.41). Estrogen deficiency resulted in marked decline in BV/TV which most probably attributed to a reduction in Tb.N. In contrast, Tb.Th was found to be preserved following estrogen loss. Hence, the period of 6 weeks post-ovariectomy was sufficient to induce osteoporosis in ovariectomized rats without affecting Tb.Th.Key words: Bone histomorphometry, menopause, estrogen deficiency, osteoporosis, ovariectomy, trabecular bone
Non-monotonic temperature dependent transport in graphene grown by Chemical Vapor Deposition
Temperature-dependent resistivity of graphene grown by chemical vapor
deposition (CVD) is investigated. We observe in low mobility CVD graphene
device a strong insulating behavior at low temperatures and a metallic behavior
at high temperatures manifesting a non-monotonic in the temperature dependent
resistivity.This feature is strongly affected by carrier density modulation. To
understand this anomalous temperature dependence, we introduce thermal
activation of charge carriers in electron-hole puddles induced by randomly
distributed charged impurities. Observed temperature evolution of resistivity
is then understood from the competition among thermal activation of charge
carriers, temperature-dependent screening and phonon scattering effects. Our
results imply that the transport property of transferred CVD-grown graphene is
strongly influenced by the details of the environmentComment: 7 pages, 3 figure
Supersymmetric quantum mechanics with nonlocal potentials
We consider supersymmetric quantum mechanical models with both local and
nonlocal potentials. We present a nonlocal deformation of exactly solvable
local models. Its energy eigenfunctions and eigenvalues are determined exactly.
We observe that both our model Hamiltonian and its supersymmetric partner may
have normalizable zero-energy ground states, in contrast to local models with
nonperiodic or periodic potentials.Comment: 4 pages, REVTeX, Minor revisions for clarificatio
Chiral bosonization for non-commutative fields
A model of chiral bosons on a non-commutative field space is constructed and
new generalized bosonization (fermionization) rules for these fields are given.
The conformal structure of the theory is characterized by a level of the
Kac-Moody algebra equal to where is the
non-commutativity parameter and chiral bosons living in a non-commutative
fields space are described by a rational conformal field theory with the
central charge of the Virasoro algebra equal to 1. The non-commutative chiral
bosons are shown to correspond to a free fermion moving with a speed equal to where is the speed of light. Lorentz
invariance remains intact if is rescaled by . The
dispersion relation for bosons and fermions, in this case, is given by .Comment: 16 pages, JHEP style, version published in JHE
Successful pleurodesis with OK-432 in preterm infants with persistent pleural effusion
OK-432 (picibanil) is an inactivated preparation of Streptococcus pyogenes that causes pleurodesis by inducing a strong inflammatory response. Intrapleural instillation of OK-432 has recently been used to successfully treat neonatal and fetal chylothorax. Here we report a trial of intrapleural instillation of OK-432 in two preterm infants who were born with hydrops fetalis and massive bilateral pleural effusion. Both cases showed persistent pleural effusion, refractory to conservative treatment, up to postnatal days 26 and 46, respectively. An average of 80 to 140 mL of pleural fluid was drained daily. In case 1, the infant was treated with OK-432 during the fetal period at gestation 28 weeks and 4 days of gestation, but showed recurrence of pleural effusion and progressed into hydrops. Within two to three days after OK-432 injection, the amount of pleural fluid drainage was dramatically decreased and there was no reaccumulation. We did not observe any side effects related to OK-432 injection. We suggest that OK-432 should be considered as a therapeutic option in infants who have persistent pleural effusion for more than four weeks, with the expectation of the early removal of the chest tube and a good outcome
New Solution of D=11 Supergravity on S^7 from D=4
A new static partially twisted solution of N=4, SO(4) gauged supergravity in
D=11 is obtained in this work using Cveti\^c et al embedding of four
dimensional into eleven dimensional supergravities. In four dimensions we get
two solutions: an asymptotic one corresponding to and a near horizon
fixed point solution of the form . Hence, while the former
solution has 32 supercharges the latter turns out to have only 4 conserved.
Moreover, we managed to find an exact interpolating solution, thus connecting
the above two. Aiming at a future study of duality for the theory at
hand we derived the Penrose limit of the four dimensional solutions.
Interestingly the pp-wave limit of the near horizon solution suggests itself as
being of the supernumerary supersymmetric type. In D=11 we exhibit the uplift
of the four dimensional solutions: one associated to and the
other to a foliation of , as well as their pp-wave
limits.Comment: 14 pages, LaTe
Probing the fuzzy sphere regularisation in simulations of the 3d \lambda \phi^4 model
We regularise the 3d \lambda \phi^4 model by discretising the Euclidean time
and representing the spatial part on a fuzzy sphere. The latter involves a
truncated expansion of the field in spherical harmonics. This yields a
numerically tractable formulation, which constitutes an unconventional
alternative to the lattice. In contrast to the 2d version, the radius R plays
an independent r\^{o}le. We explore the phase diagram in terms of R and the
cutoff, as well as the parameters m^2 and \lambda. Thus we identify the phases
of disorder, uniform order and non-uniform order. We compare the result to the
phase diagrams of the 3d model on a non-commutative torus, and of the 2d model
on a fuzzy sphere. Our data at strong coupling reproduce accurately the
behaviour of a matrix chain, which corresponds to the c=1-model in string
theory. This observation enables a conjecture about the thermodynamic limit.Comment: 31 pages, 15 figure
Near-Horizon Conformal Symmetry and Black Hole Entropy in Any Dimension
Recently, Carlip proposed a derivation of the entropy of the two-dimensional
dilatonic black hole by investigating the Virasoro algebra associated with a
newly introduced near-horizon conformal symmetry. We point out not only that
the algebra of these conformal transformations is not well defined on the
horizon, but also that the correct use of the eigenvalue of the operator
yields vanishing entropy. It has been shown that these problems can be resolved
by choosing a different basis of the conformal transformations which is regular
even at the horizon. We also show the generalization of Carlip's derivation to
any higher dimensional case in pure Einstein gravity. The entropy obtained is
proportional to the area of the event horizon, but it also depends linearly on
the product of the surface gravity and the parameter length of a horizon
segment in consideration. We finally point out that this derivation of black
hole entropy is quite different from the ones proposed so far, and several
features of this method and some open issues are also discussed.Comment: 14 pages, no figur
Tackling tuberculosis: insights from an international TB Summit in London
Tuberculosis (TB) poses a grave predicament to the world as it is not merely a scientific challenge but a socio-economic burden as well. A prime cause of mortality in human due to an infectious disease; the malady and its cause, Mycobacterium tuberculosis have remained an enigma with many questions that remain unanswered. The ability of the pathogen to survive and switch between varied physiological states necessitates a protracted therapeutic regimen that exerts an excessive strain on low-resource countries. To complicate things further, there has been a significant rise of antimicrobial resistance. Existing control measures, including treatment regimens have remained fairly uniform globally for at least half a century and require reinvention. Overcoming the societal and scientific challenges requires an increase in dialog to identify key regions that need attention and effective partners with whom successful collaborations can be fostered. In this report, we explore the discussions held at the International TB Summit 2015 hosted by EuroSciCon, which served as an excellent platform for researchers to share their recent findings. Ground-breaking results require outreach to affect policy design, governance and control of the disease. Hence, we feel it is important that meetings such as these reach a wider, global audience
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