122 research outputs found
Fermionic Wigs for BTZ Black Holes
We compute the wig for the BTZ black hole, namely the complete non-linear
solution of supergravity equations with all fermionic zero modes. We use a
"gauge completion" method starting from AdS_3 Killing spinors to generate the
gravitinos fields associated to the BH and we compute the back-reaction on the
metric. Due to the anticommutative properties of the fermionic hairs the
resummation of these effects truncates at some order. We illustrate the
technique proposed in a precedent paper in a very explicit and analytical form.
We also compute the mass, the angular momentum and other charges with their
corrections.Comment: 11 pages, no figure
Fermionic Corrections to Fluid Dynamics from BTZ Black Hole
We reconstruct the complete fermionic orbit of the non-extremal BTZ black
hole by acting with finite supersymmetry transformations. The solution
satisfies the exact supergravity equations of motion to all orders in the
fermonic expansion and the final result is given in terms of fermionic
bilinears. By fluid/gravity correspondence, we derive linearized Navier-Stokes
equations and a set of new differential equations from Rarita-Schwinger
equation. We compute the boundary energy-momentum tensor and we interpret the
result as a perfect fluid with a modified definition of fluid velocity.
Finally, we derive the modified expression for the entropy of the black hole in
terms of the fermionic bilinears.Comment: 21 pages, Latex2e, no figure
Fermions, Wigs, and Attractors
We compute the modifications to the attractor mechanism due to fermionic
corrections. In N=2, D=4 supergravity, at the fourth order, we find a new
contribution to the horizon values of the scalar fields of the vector
multiplets.Comment: v2 : 1+11 pages; paper reorganized in Sections; Sec. 5 added, with
detailed treatment of the axion-dilaton model; some typos fixed and
references adde
Supersymmetric Fluid Dynamics
Recently Navier-Stokes (NS) equations have been derived from the duality
between the black branes and a conformal fluid on the boundary of AdS_5.
Nevertheless, the full correspondence has to be established between solutions
of supergravity in AdS_5 and supersymmetric field theories on the boundary.
That prompts the construction of NS equations for a supersymmetric fluid. In
the framework of rigid susy, there are several possibilities and we propose one
candidate. We deduce the equations of motion in two ways: both from the
divergenless condition on the energy-momentum tensor and by a suitable
parametrization of the auxiliary fields. We give the complete component
expansion and a very preliminary analysis of the physics of this supersymmetric
fluid.Comment: 24 pages, Latex2
Transit Timing Observations of the Extrasolar Hot-Neptune Planet GL 436b
Gliese 436 is an M dwarf with a mass of 0.45 Msun and hosts the extrasolar
planet GL 436b [3, 6, 7, 2], which is currently the least massive transiting
planet with a mass of ~23.17 Mearth [10], and the only planet known to transit
an M dwarf. GL 436b represents the first transiting detection of the class of
extrasolar planets known as "Hot Neptunes" that have masses within a few times
that of Neptune's mass (~17 Mearth) and orbital semimajor axis <0.1 AU about
the host star. Unlike most other known transiting extrasolar planets, GL 436b
has a high eccentricity (e~0.16). This brings to light a new parameter space
for habitability zones of extrasolar planets with host star masses much smaller
than typical stars of roughly a solar mass. This unique system is an ideal
candidate for orbital perturbation and transit-time variation (TTV) studies to
detect smaller, possibly Earth-mass planets in the system. In April 2008 we
began a long-term intensive campaign to obtain complete high-precision light
curves using the Apache Point Observatory's 3.5-meter telescope, NMSU's 1-meter
telescope (located at APO), and Sommers Bausch Observatory's 24" telescope.
These light curves are being analyzed together, along with amateur and other
professional astronomer observations. Results of our analysis are discussed.
Continued measurements over the next few years are needed to determine if
additional planets reside in the system, and to study the impact of other
manifestations on the light curves, such as star spots and active regions.Comment: 4 pages, 3 figures. To appear in "Proceedings of the 15th Cambridge
Workshop on Cool Stars, Stellar Systems and the Sun", 2009, AIP Conference
Proceedings vol. 1094, ed. Eric Stempel
Sex disparities in efficacy in covid-19 vaccines: A systematic review and meta-analysis
Sex differences in adaptive and innate immune responses have been shown to occur and anecdotal reports suggest that vaccine efficacy and safety may be sex-dependent. We investigated the influence of sex on the efficacy of COVID-19 vaccines through a systematic review and meta-analysis of clinical trials on COVID-19 vaccines. The safety profile of COVID-19 vaccines was also investigated. A systematic review included eligible articles published in three databases and three websites. A meta-analysis of available data, stratified by sex, was conducted. Statistical analysis was performed using the Hartung\u2013Knapp\u2013Sidik\u2013Jonkman method, as well as influence and heterogeneity analysis. Pooled analysis showed significantly higher efficacy, measured as the rate of new COVID-19 cases, in men compared to women in the vaccine group (OR = 0.67, 95% CI 0.48\u20130.94). No sex differences were found in the rate of new cases in the control group (OR = 0.92, 95% CI 0.78\u20131.09). Safety profiles derived from pharmacovigilance reports appear to indicate increased toxicity in women. In conclusion, evidence of a potential role of sex in COVID-19 vaccine efficacy was described. It strengthens the need to include sex as a core variable in the clinical trial design of COVID-19 vaccines
Synthesis, characterization and photocatalytic properties of nanostructured lanthanide doped β-NaYFâ/TiOâ composite films
The photocatalytic approach is known to be one of the most promising advanced oxidation processes for the tertiary treatment of polluted water. In this paper, β-NaYF4/TiO2 composite films have been synthetized through a novel solâgel/spin-coating approach using a mixture of β-diketonate complexes of Na and Y, and Yb3+, Tm3+, Gd3+, Eu3+ as doping ions, together with the TiO2 P25 nanoparticles. The herein pioneering approach represents an easy, straightforward and industrially appealing method for the fabrication of doped β-NaYF4/TiO2 composites. The effect of the doped β-NaYF4 phase on the photocatalytic activity of TiO2 for the degradation of methylene blue (MB) has been deeply investigated. In particular, the upconverting TiO2/β-NaYF4: 20%Yb, 2% Gd, x% Tm (xâ=â0.5 and 1%) and the downshifting TiO2/β-NaYF4: 10% Eu composite films have been tested on MB degradation both under UV and visible light irradiation. An improvement up to 42.4% in the degradation of MB has been observed for the TiO2/β-NaYF4: 10% Eu system after 240 min of UV irradiation
Protective continuous ventilation strategy during cardiopulmonary bypass in children undergoing surgery for congenital heart disease: a prospective study
OBJECTIVES: The aim of this study was to evaluate if a 'protective' (low-tidal/low-frequency) ventilation strategy can shorten the postoperative ventilation time and minimize acute lung injury in children with congenital heart disease (CHD) undergoing repair with cardiopulmonary bypass (CPB). METHODS: This is a single-centre prospective, interventional study, including children with CHD under the age of 5 years, undergoing open-heart surgery with a CPB >60 min, in hypothermia, haemodynamically stable, and without evident genetic abnormalities. Assist-control ventilation (tidal volume of 4 ml/kg, 10 breaths/min, positive end-expiratory pressure 5 cmH2O and FiO2 0.21) was applied in a cohort of patients during CPB. We compared clinical outcomes and in fully ventilated versus non-ventilated (control) patients. Propensity score was used to weigh ventilated and control groups to correct for the effect of other confounding clinical variables. Clinical and ventilation parameters and lung inflammatory biomarkers in tracheal aspirates were measured. The primary outcome was the postoperative intubation time of more or less than 48 h. RESULTS: We included 140 children (53 ventilated, 87 non-ventilated) with different CHD. There were no deaths or adverse events in ventilated patients. Using a weighted generalized linear model, we found no sufficient evidence for an effect of intraoperative ventilation on postoperative intubation time [estimate 0.13 (95% confidence interval, -0.08; 0.35), P = 0.22]. CONCLUSIONS: Continuous low-tidal/low-frequency mechanical ventilation during CPB is safe and harmless. However, no significant advantages were found when compared to non-ventilated patients in terms of postoperative ventilation time
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