65 research outputs found
O(d,d)-invariance in inhomogeneous string cosmologies with perfect fluid
In the first part of the present paper, we show that O(d,d)-invariance
usually known in a homogeneous cosmological background written in terms of
proper time can be extended to backgrounds depending on one or several
coordinates (which may be any space-like or time-like coordinate(s)). In all
cases, the presence of a perfect fluid is taken into account and the equivalent
duality transformation in Einstein frame is explicitly given. In the second
part, we present several concrete applications to some four-dimensional
metrics, including inhomogeneous ones, which illustrate the different duality
transformations discussed in the first part. Note that most of the dual
solutions given here do not seem to be known in the literature.Comment: 25 pages, no figures, Latex. Accepted for publication in General
Relativity and Gravitatio
A Comprehensive Review on Copemyl(\uae)
Economic sustainability is of paramount importance in the rapidly evolving therapeutic scenario of multiple sclerosis (MS). Glatiramoids are a class of drugs whose forefather, glatiramer acetate, has been used as a disease modifying drug (DMD) in patients with MS for over 20 years. Its patent expired in 2015; new versions of such drug are nowadays available on the market, potentially contributing to lowering prices and enhancing a better allocation of economic resources. In this review, we analyze the recommendations underlying the approval of both generic drugs and biosimilars by regulatory authorities, and we provide methodological tools to contextualize the design of studies on these new classes of drugs. We examine in more detail the preclinical and clinical data of Copemyl(\uae), a new member of the glatiramoid class, focusing on its biological and immunological properties and illustrating randomized controlled trials that led to its authorization
Anisotropic Four-Dimensional NS-NS String Cosmology
An anisotropic (Bianchi type I) cosmology is considered in the
four-dimensional NS-NS sector of low-energy effective string theory coupled to
a dilaton and an axion-like -field within a de Sitter-Einstein frame
background. The time evolution of this Universe is discussed in both the
Einstein and string frames.Comment: Revtex, 5 pages, 3 figure
Bianchi Type I Cosmologies in Arbitrary Dimensional Dilaton Gravities
We study the low energy string effective action with an exponential type
dilaton potential and vanishing torsion in a Bianchi type I space-time
geometry. In the Einstein and string frames the general solution of the
gravitational field equations can be expressed in an exact parametric form.
Depending on the values of some parameters the obtained cosmological models can
be generically divided into three classes, leading to both singular and
nonsingular behaviors. The effect of the potential on the time evolution of the
mean anisotropy parameter is also considered in detail, and it is shown that a
Bianchi type I Universe isotropizes only in the presence of a dilaton field
potential or a central deficit charge.Comment: REVTEX, 10 pages, 8 figure
Early gut microbiota signature of aGvHD in children given allogeneic hematopoietic cell transplantation for hematological disorders
The onset of acute Graft-versus-Host Disease (aGvHD) has been correlated with the gut microbiota (GM) composition, but experimental observations are still few, mainly involving cohorts of adult patients. In the current scenario where fecal microbiota transplantation has been used as a pioneer therapeutic approach to treat steroid-refractory aGvHD, there is an urgent need to expand existing observational studies of the GM dynamics in Hematopoietic Stem Cell Transplantation (HSCT). Aim of the present study is to explore the GM trajectory in 36 pediatric HSCT recipients in relation to aGvHD onset
Cosmic Billiards with Painted Walls in Non-Maximal Supergravities: a worked out example
The derivation of smooth cosmic billiard solutions through the compensator
method is extended to non maximal supergravities. A new key feature is the
non-maximal split nature of the scalar coset manifold. To deal with this, one
needs the theory of Tits Satake projections leading to maximal split projected
algebras. Interesting exact solutions that display several smooth bounces can
thus be derived. From the analysis of the Tits Satake projection emerges a
regular scheme for all non maximal supergravities and a challenging so far
unobserved structure, that of the paint group G-paint. This latter is preserved
through dimensional reduction and provides a powerful tool to codify solutions.
It appears that the dynamical walls on which the cosmic ball bounces come
actually in painted copies rotated into each other by G-paint. The effective
cosmic dynamics is that dictated by the maximal split Tits Satake manifold plus
paint. We work out in details the example provided by N=6,D=4 supergravity,
whose scalar manifold is the special Kahlerian SO*(12)}/SU(6)xU(1). In D=3 it
maps to the quaternionic E_7(-5)/ SO(12) x SO(3). From this example we extract
a scheme that holds for all supergravities with homogeneous scalar manifolds
and that we plan to generalize to generic special geometries. We also comment
on the merging of the Tits-Satake projection with the affine Kac--Moody
extensions originating in dimensional reduction to D=2 and D=1.Comment: 52 pages, 4 figures, 9 tables, paper. Few misprints correcte
Rotational Perturbations in Neveu-Schwarz-Neveu-Schwarz String Cosmology
First order rotational perturbations of the flat Friedmann-Robertson-Walker
(FRW) metric are considered in the framework of four dimensional
Neveu-Schwarz-Neveu-Schwarz (NS-NS) string cosmological models coupled with
dilaton and axion fields. The decay rate of rotation depends mainly upon the
dilaton field potential U. The equation for rotation imposes strong limitations
upon the functional form of U, restricting the allowed potentials to two: the
trivial case U=0 and a generalized exponential type potential. In these two
models the metric rotation function can be obtained in an exact analytic form
in both Einstein and string frames. In the potential-free case the decay of
rotational perturbations is governed by an arbitrary function of time while in
the presence of a potential the rotation tends rapidly to zero in both Einstein
and string frames.Comment: 13 pages, 8 figure
Does accelerating universe indicates Brans-Dicke theory
The evolution of universe in Brans-Dicke (BD) theory is discussed in this
paper.
Considering a parameterized scenario for BD scalar field
which plays the role of gravitational "constant" ,
we apply the Markov Chain Monte Carlo method to investigate a global
constraints on BD theory with a self-interacting potential according to the
current observational data: Union2 dataset of type supernovae Ia (SNIa),
high-redshift Gamma-Ray Bursts (GRBs) data, observational Hubble data (OHD),
the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and
the cosmic microwave background (CMB) data. It is shown that an expanded
universe from deceleration to acceleration is given in this theory, and the
constraint results of dimensionless matter density and parameter
are, and
which is consistent with the
result of current experiment exploration, . In
addition, we use the geometrical diagnostic method, jerk parameter , to
distinguish the BD theory and cosmological constant model in Einstein's theory
of general relativity.Comment: 16 pages, 3 figure
Management of hepatitis B virus prophylaxis in patients treated with disease-modifying therapies for multiple sclerosis: a multicentric Italian retrospective study
Background: Patients with multiple sclerosis (MS) often receive disease-modifying therapies (DMTs) that can expose them to reactivation of potential occult hepatitis B virus (HBV) infection (pOBI). We aimed to evaluate the MS Centers behavior regarding HBV screening and prophylaxis in a large cohort of MS patients receiving anti-CD20 or cladribine. Methods: Retrospective, multicentric study recruiting Italian MS patients treated with rituximab, ocrelizumab and cladribine. Results: We included 931 MS patients from 15 centers. All but 38 patients performed a complete HBV screening. Patients' age > 50 years was significantly associated with no history of vaccination and HBsAb titres < 100 mIU at baseline (p < 0.001). No significant correlation was found between post-vaccination HBsAb titres and type of treatment (p = 0.5), pre-or post-therapy vaccination (p = 0.2) and number of previous DMTs (p = 0.2). Among pOBI patients (n = 53), 21 received antiviral prophylaxis, while only 13 had HBV DNA monitoring and 19 patients neither monitored HBV DNA nor received prophylaxis. Conclusions: Baseline HBV screening in patients receiving anti-CD20 and cladribine is a consolidated practice. Nonetheless, HBV vaccination coverage is still lacking in such population and age is a significant factor associated with low HBV protection. Rituximab, ocrelizumab and cladribine did not impair HBV vaccine response. Almost 35% of pOBI patients fail to receive HBVr prevention. Management of HBV prophylaxis could be improved in MS patients and further prospective studies are needed to assess the effectiveness of prophylactic strategies in such patients
Long-term disability trajectories in relapsing multiple sclerosis patients treated with early intensive or escalation treatment strategies
Background and aims: No consensus exists on how aggressively to treat relapsing-remitting multiple sclerosis (RRMS) nor on the timing of the treatment. The objective of this study was to evaluate disability trajectories in RRMS patients treated with an early intensive treatment (EIT) or with a moderate-efficacy treatment followed by escalation to higher-efficacy disease modifying therapy (ESC).
Methods: RRMS patients with ⩾5-year follow-up and ⩾3 visits after disease modifying therapy (DMT) start were selected from the Italian MS Registry. EIT group included patients who received as first DMT fingolimod, natalizumab, mitoxantrone, alemtuzumab, ocrelizumab, cladribine. ESC group patients received the high efficacy DMT after ⩾1 year of glatiramer acetate, interferons, azathioprine, teriflunomide or dimethylfumarate treatment. Patients were 1:1 propensity score (PS) matched for characteristics at the first DMT. The disability trajectories were evaluated by applying a longitudinal model for repeated measures. The effect of early versus late start of high-efficacy DMT was assessed by the mean annual Expanded Disability Status Scale (EDSS) changes compared with baseline values (delta-EDSS) in EIT and ESC groups.
Results: The study cohort included 2702 RRMS patients. The PS matching procedure produced 363 pairs, followed for a median (interquartile range) of 8.5 (6.5-11.7) years. Mean annual delta-EDSS values were all significantly (p < 0.02) higher in the ESC group compared with the EIT group. In particular, the mean delta-EDSS differences between the two groups tended to increase from 0.1 (0.01-0.19, p = 0.03) at 1 year to 0.30 (0.07-0.53, p = 0.009) at 5 years and to 0.67 (0.31-1.03, p = 0.0003) at 10 years.
Conclusion: Our results indicate that EIT strategy is more effective than ESC strategy in controlling disability progression over time
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