125 research outputs found
Exact solutions of noncommutative vacuum Einstein field equations and plane-fronted gravitational waves
We construct a class of exact solutions of the noncommutative vacuum Einstein
field equations, which are noncommutative analogues of the plane-fronted
gravitational waves in classical gravity.Comment: 10 pages, comments adde
Shockwaves and deep inelastic scattering within the gauge/gravity duality
Within the gauge/gravity correspondence, we discuss the general formulation
of the shockwave metric which is dual to a 'nucleus' described by the
strongly-coupled N=4 SYM theory in the limit where the number of colors Nc is
arbitrarily large. We emphasize that the 'nucleus' must possess Nc^2 degrees of
freedom per unit volume, so like a finite-temperature plasma, in order for a
supergravity description to exist. We critically reassess previous proposals
for introducing transverse inhomogeneity in the shockwave and formulate a new
proposal in that sense, which involves no external source but requires the
introduction of an 'infrared' cutoff which mimics confinement. This cutoff
however plays no role when the shockwave is probed by a highly virtual
projectile, so like in deep inelastic scattering. We consider two such
projectiles, the dilaton and the R-current, and compute the respective
structure functions including unitarity corrections. We find that there are no
leading-twist contributions to the structure functions at high virtuality,
meaning that there are no point-like constituents in the strongly coupled
'nucleus'. In the black-disk regime at low virtuality, the structure functions
are suggestive of parton saturation with occupation numbers of order one. The
saturation momentum Qs grows with the energy like Qs^2 ~ 1/x (with x the
Bjorken variable), which is the hallmark of graviton exchanges and is also
necessary for the fulfillment of the energy-momentum sum rules.Comment: 43 page
T-Duality and Penrose limits of spatially homogeneous and inhomogeneous cosmologies
Penrose limits of inhomogeneous cosmologies admitting two abelian Killing
vectors and their abelian T-duals are found in general. The wave profiles of
the resulting plane waves are given for particular solutions. Abelian and
non-abelian T-duality are used as solution generating techniques. Furthermore,
it is found that unlike in the case of abelian T-duality, non-abelian T-duality
and taking the Penrose limit are not commutative procedures.Comment: 16 pages, 4 figures. Discussion on non-abelian T-duality expande
Eikonal Methods in AdS/CFT: BFKL Pomeron at Weak Coupling
We consider correlators of N=4 super Yang Mills of the form A ~ < O_1 O_2
O*_1 O*_2 >, where the operators O_1 and O_2 are scalar primaries. In
particular, we analyze this correlator in the planar limit and in a Lorentzian
regime corresponding to high energy interactions in AdS. The planar amplitude
is dominated by a Regge pole whose nature varies as a function of the 't Hooft
coupling g^2. At large g, the pole corresponds to graviton exchange in AdS,
whereas at weak g, the pole is that of the hard perturbative BFKL pomeron. We
concentrate on the weak coupling regime and analyze pomeron exchange directly
in position space. The analysis relies heavily on the conformal symmetry of the
transverse space E^2 and of its holographic dual hyperbolic space H_3,
describing with an unified language, both the weak and strong 't Hooft coupling
regimes. In particular, the form of the impact factors is highly constrained in
position space by conformal invariance. Finally, the analysis suggests a
possible AdS eikonal resummation of multi-pomeron exchanges implementing AdS
unitarity, which differs from the usual 4-dimensional eikonal exponentiation.
Relations to violations of 4-dimensional unitarity at high energy and to the
onset of nonlinear effects and gluon saturation become immediate questions for
future research.Comment: 42 pages, 13 figure
Geometrothermodynamics of five dimensional black holes in Einstein-Gauss-Bonnet-theory
We investigate the thermodynamic properties of 5D static and spherically
symmetric black holes in (i) Einstein-Maxwell-Gauss-Bonnet theory, (ii)
Einstein-Maxwell-Gauss-Bonnet theory with negative cosmological constant, and
in (iii) Einstein-Yang-Mills-Gauss-Bonnet theory. To formulate the
thermodynamics of these black holes we use the Bekenstein-Hawking entropy
relation and, alternatively, a modified entropy formula which follows from the
first law of thermodynamics of black holes. The results of both approaches are
not equivalent. Using the formalism of geometrothermodynamics, we introduce in
the manifold of equilibrium states a Legendre invariant metric for each black
hole and for each thermodynamic approach, and show that the thermodynamic
curvature diverges at those points where the temperature vanishes and the heat
capacity diverges.Comment: New sections added, references adde
Gravitational collapse of spherically symmetric stars in noncommutative general relativity
Gravitational collapse of a class of spherically symmetric stars is investigated. We quantise the geometries describing the gravitational collapse by a deformation quantisation procedure. This gives rise to oncommutative spacetimes with gravitational collapse
Development of a Tool to Measure the Clinical Response to Biologic Therapy in Uncontrolled Severe Asthma: The FEV1, Exacerbations, Oral Corticosteroids, Symptoms Score
Background: There is a lack of tools to quantify the response to monoclonal antibodies (mAbs) holistically in severe uncontrolled asthma patients. Objective: To develop a valid score to assist specialists in this clinical context. Methods: The score was developed in four subsequent phases: (1) elaboration of the theoretical model of the construct intended to be measured (response to mAbs); (2) definition and selection of items and measurement instruments by Delphi survey; (3) weight assignment of the selected items by multicriteria decision analysis using the Potentially All Pairwise RanKings of All Possible Alternatives methodology using the 1000minds software; and (4) face validity assessment of the obtained score. Results: Four core items, with different levels of response for each, were selected: severe exacerbations, oral corticosteroid use, symptoms (evaluated by Asthma Control Test), and bronchial obstruction (assessed by FEV1 percent predicted). Severe exacerbations and oral corticosteroid maintenance dose were weighted most heavily (38% each), followed by symptoms (13%) and FEV1 (11%). Higher scores in the weighted system indicate a better response and the range of responses runs from 0 (worsening) to 100 (best possible response). Face validity was high (intraclass correlation coefficient of 0.86). Conclusions: The FEV1, exacerbations, oral corticosteroids, symptoms score allows clinicians to quantify response in severe uncontrolled asthma patients who are being treated with mAbs
Crop loading studies on âCariciaâ and âEvaâ apples grown in a mild winter area
The crop load level of an apple (Malus Ă domestica Borkh.) tree impacts fruit yield and quality parameters, tree vigor and biennial bearing. The optimal crop load is that which allows for consistent annual cropping and fruit quality acceptable to the market. We evaluated the effect of crop load on yield and fruit quality of two low-chill apples cv. âCariciaâ and âEvaâ, growing in a mild winter area. During 2010 and 2011 crop load was manually adjusted from 2 or 3 to 17 fruits cmâ2 of trunk cross-sectional area (TCSA). Fruit yield was positively related to crop load in both cultivars but mean fruit weight diminished as the crop load increased. For both cultivars, the production of non-commercial and small-sized fruit increased, whereas production of middle-sized fruit diminished as the fruit load increased. Shoot length was not affected by crop load in âEvaâ whereas it was reduced in âCariciaâ. Red skin color (RSC %) had a quadratic response to crop load in âCariciaâ. On the other hand, the RSC % of âEvaâ fruit was adjusted to a negative logarithmic model as an effect of crop load increment. No biennial bearing was observed in either cultivar. This research study suggests that the maximum limit of crop load for both cultivars is 7 fruits cmâ2 of TCSA, and the lower limit of crop load was 3 fruits cmâ2 of TCSA for âEvaâ and 5 fruits cmâ2 of TCSA for âCariciaâ
EPIdemiology of Surgery-Associated Acute Kidney Injury (EPIS-AKI) : Study protocol for a multicentre, observational trial
More than 300 million surgical procedures are performed each year. Acute kidney injury (AKI) is a common complication after major surgery and is associated with adverse short-term and long-term outcomes. However, there is a large variation in the incidence of reported AKI rates. The establishment of an accurate epidemiology of surgery-associated AKI is important for healthcare policy, quality initiatives, clinical trials, as well as for improving guidelines. The objective of the Epidemiology of Surgery-associated Acute Kidney Injury (EPIS-AKI) trial is to prospectively evaluate the epidemiology of AKI after major surgery using the latest Kidney Disease: Improving Global Outcomes (KDIGO) consensus definition of AKI. EPIS-AKI is an international prospective, observational, multicentre cohort study including 10 000 patients undergoing major surgery who are subsequently admitted to the ICU or a similar high dependency unit. The primary endpoint is the incidence of AKI within 72 hours after surgery according to the KDIGO criteria. Secondary endpoints include use of renal replacement therapy (RRT), mortality during ICU and hospital stay, length of ICU and hospital stay and major adverse kidney events (combined endpoint consisting of persistent renal dysfunction, RRT and mortality) at day 90. Further, we will evaluate preoperative and intraoperative risk factors affecting the incidence of postoperative AKI. In an add-on analysis, we will assess urinary biomarkers for early detection of AKI. EPIS-AKI has been approved by the leading Ethics Committee of the Medical Council North Rhine-Westphalia, of the Westphalian Wilhelms-University MĂŒnster and the corresponding Ethics Committee at each participating site. Results will be disseminated widely and published in peer-reviewed journals, presented at conferences and used to design further AKI-related trials. Trial registration number NCT04165369
Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at âNN = 5.02 TeV
The second-order Fourier coefficients (Ï
) characterizing the azimuthal distributions of ΄(1S) and ΄(2S) mesons produced in PbPb collisions at = 5.02 TeV are studied. The ΄mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb. The scalar product method is used to extract the Ï
coefficients of the azimuthal distributions. Results are reported for the rapidity range |y| < 2.4, in the transverse momentum interval 0 < p < 50 GeV/c, and in three centrality ranges of 10â30%, 30â50% and 50â90%. In contrast to the J/Ï mesons, the measured Ï
values for the ΄ mesons are found to be consistent with zero
- âŠ