Separating expansion from contraction and generalizing TOV condition in spherically symmetric models with pressure

We investigate spherically symmetric solutions with pressure and discuss the existence of a dividing shell separating expanding and collapsing regions. We perform a 3+1 splitting and obtain gauge invariant conditions relating not only the intrinsic spatial curvature of the shells to the ADM mass, but also a function of the pressure which we introduce that generalises the Tolman-Oppenheimer-Volkoff equilibrium condition. We consider the particular case of a Lema\^itre-Tolman dust models with a cosmological constant (a $\Lambda$-CDM model) as an example of our results.Comment: 4pp, 1fig, AIP Conference: Proc. XXXI Spanish Relat. Meeting, ERE08, Salamanca, Spain, 15-19 Sept., 2008 Septembre, Salamanca, Espagn

Separating expansion from contraction: generalized TOV condition, LTB models with pressure and Λ\LambdaCDM

We discuss the existence of a dividing shell separating expanding and collapsing regions in spherically symmetric solutions with pressure. We obtain gauge invariant conditions relating not only the intrinsic spatial curvature of the shells to the ADM mass, but also a function of the pressure which we introduce that generalises the Tolman-Oppenheimer-Volkoff equilibrium condition, in the framework of a 3+1 spacetime splitting. We consider the particular case of a Lema\^itre-Tolman-Bondi dust models with a cosmological constant (a $\Lambda$-CDM model) as an example of our results.Comment: Proceedings of 'Invisible Universe International Conference', Paris, June 29- July 3, 2009 ; 5pp, 4 fig

Dynamical analysis of the redshift drift in FLRW universes

Redshift drift is the phenomenon whereby the observed redshift between an emitter and observer comoving with the Hubble flow in an expanding FLRW universe will slowly evolve -- on a timescale comparable to the Hubble time. In a previous article [JCAP 04 (2020) 043; \arXiv{2001.11964}] three of the current authors had performed a cosmographic analysis of the redshift drift in a FLRW universe, temporarily putting aside the issue of dynamics (the Friedmann equations). In the current article we now add dynamics, still within the framework of an exact FLRW universe. We shall develop a suitable generic matter model and apply it to both standard FLRW and various dark energy models. Furthermore, we shall also present a section analyzing the utility of using alternative cosmographic variables to describe the redshift drift data.Comment: 37 pages, 19 figures. New section adde

Extensively drug-resistant Pseudomonas aeruginosa: clinical features and treatment with ceftazidime/avibactam and ceftolozane/tazobactam in a tertiary care university hospital center in Portugal – A cross-sectional and retrospective observational study

IntroductionExtensively drug-resistant Pseudomonas aeruginosa (XDR-PA) is a growing concern due to its increasing incidence, limited therapeutic options, limited data on the optimal treatment, and high mortality rates. The study aimed to characterize the population, the outcome and the microbiological characteristics of XDR-PA identified in a Portuguese university hospital center.MethodsAll XDR-PA isolates between January 2019 and December 2021 were identified. XDR-PA was defined as resistance to piperacillin-tazobactam, third and fourth generation cephalosporins, carbapenems, aminoglycosides and fluoroquinolones. A retrospective analysis of the medical records was performed.ResultsOne hundred seventy-eight individual episodes among 130 patients with XDR-PA detection were identified. The most common sources of infection were respiratory (32%) and urinary tracts (30%), although skin and soft tissue infections (18%) and primary bacteremia (14%) were also prevalent. Colonization was admitted in 64 cases. Several patients had risk factors for complicated infections, most notably immunosuppression, structural lung abnormalities, major surgery, hemodialysis or foreign intravascular or urinary devices. XDR-PA identification was more frequent in male patients with an average age of 64.3 ± 17.5 years. One non-susceptibility to colistin was reported. Only 12.4% were susceptible to aztreonam. Ceftazidime-avibactam (CZA) was susceptible in 71.5% of the tested isolates. Ceftolozane-tazobactam (C/T) was susceptible in 77.5% of the tested isolates. Antibiotic regimens with XDR-PA coverage were reserved for patients with declared infection, except to cystic fibrosis. The most frequently administered antibiotics were colistin (41 cases), CZA (39 cases), and C/T (16 cases). When combination therapy was used, CZA plus colistin was preferred. The global mortality rate among infected patients was 35.1%, significantly higher in those with hematologic malignancy (50.0%, p < 0.05), followed by the ones with bacteremia (44.4%, p < 0.05) and those medicated with colistin (39.0%, p < 0.05), especially the ones with respiratory infections (60.0%). Among patients treated with CZA or C/T, the mortality rate seemed to be lower.DiscussionXDR-PA infections can be severe and difficult to treat, with a high mortality rate. Even though colistin seems to be a viable option, it is likely less safe and efficient than CZA and C/T. To the best of the authors’ knowledge, this is the first description of the clinical infection characteristics and treatment of XDR-PA in Portugal

Score CRUSADE: será ainda um bom score para prever a hemorragia na síndrome coronária aguda?

Introduction: Major bleeding is a serious complication of acute coronary syndrome (ACS) andis associated with a worse prognosis. The CRUSADE bleeding score is used to stratify the risk ofmajor bleeding in ACS.Objective: To assess the predictive ability of the CRUSADE score in a contemporary ACS popu-lation.Methods: In a single-center retrospective study of 2818 patients admitted with ACS, the CRU-SADE score was calculated for each patient and its discrimination and goodness of fit wereassessed by the area under the receiver operating characteristic curve (AUC) and by the Hosmer-Lemeshow test, respectively. Predictors of in-hospital major bleeding (IHMB) were determined.Results: The IHMB rate was 1.8%, significantly lower than predicted by the CRUSADE score (7.1%,p<0.001). The incidence of IHMB was 0.5% in the very low risk category (rate predicted by thescore 3.1%), 1.5% in the low risk category (5.5%), 1.6% in the moderate risk category (8.6%),5.5% in the high risk category (11.9%), and 4.4% in the very high risk category (19.5%). Thepredictive ability of the CRUSADE score for IHMB was only moderate (AUC 0.73).The in-hospital mortality rate was 4.0%. Advanced age (p=0.027), femoral vascular access(p=0.004), higher heart rate (p=0.047) and ticagrelor use (p=0.027) were independent predictorsof IHMB.Conclusions: The CRUSADE score, although presenting some discriminatory power, significantlyoverestimated the IHMB rate, especially in patients at higher risk. These results questionwhether the CRUSADE score should continue to be used in the stratification of ACS.Introdução: A hemorragia major (HM) é uma complicação grave da síndrome coronária aguda (SCA) e está associada a pior prognóstico. O score CRUSADE permite estratificar o risco de HMna SCA.Objetivo: Avaliar a capacidade preditiva do score CRUSADE numa populac ̧ão contemporânea deSCA.Métodos: Estudo unicêntrico e retrospetivo com 2.818 doentes admitidos por SCA. O scoreCRUSADE foi calculado para cada doente, a sua discriminac ̧ão e calibrac ̧ão foram avaliadas pelaárea abaixo da curva (AUC) Receiver Operating Characteristic e pelo teste Hosmer-Lemeshow,respetivamente. Foram determinados os preditores de HM intra-hospitalar (HMIH).Resultados: A taxa de HMIH foi de 1.8%, valor significativamente inferior ao estimado peloscore CRUSADE (7,1%, p<0,001). A incidência de HMIH nas diferentes categorias foi de 0,5% nade muito baixo risco (taxa estimada pelo score de 3,1%); 1,5% na de baixo (estimada de 5,5%);1,6% na de moderado (estimada de 8,6%); 5,5% na de elevado (estimada de 11,9%) e 4,4% na demuito elevado (estimada de 19,5%). A capacidade preditora do score CRUSADE para HMIH foiapenas moderada (AUC 0,73). A taxa de mortalidade intra-hospitalar foi de 4,0%. A idade maisavanc ̧ada (p=0,027), o acesso vascular femoral (p=0,004), a frequência cardíaca mais elevada(p=0,047) e o ticagrelor (p=0,027) foram preditores independentes de HMIH.Conclusão: O score CRUSADE, apesar de apresentar algum poder discriminatório, sobrestimou de forma significativa a taxa de HMIH, principalmente nos doentes de maior risco. Esses resultados questionam se o score CRUSADE deverá continuar a ser usado na estratificação da SC

Spherically symmetric models with pressure: separating expansion from contraction and generalizing TOV condition

16 pages, 9 figures, 2 appendix.-- PACS numbers: 98.80.-k, 98.80.Cq, 98.80.Jk, 95.30.Sf, 04.40.Nr, 04.20.JbWe investigate spherically symmetric perfect fluid spacetimes and discuss the existence and stability of a dividing shell separating expanding and collapsing regions. We perform a 3+1 splitting and obtain gauge invariant conditions relating the intrinsic spatial curvature of the shells to the ADM mass and to a function of the pressure which we introduce and that generalises the Tolman-Oppenheimer-Volkoff equilibrium condition. We analyse the particular cases of the Lema\^itre-Tolman-Bondi dust models with a cosmological constant as an example of a $\Lambda$-CDM model and its generalization to contain a central perfect fluid core. These models provide simple, but physically interesting illustrations of our results.The work of MLeD is supported by CSIC (Spain) under the contract JAEDoc072, with partial support from CICYT project FPA2006-05807, at the IFT, Universidad Autonoma de Madrid, Spain, and was also supported by FCT (Portugal)under the grant SFRH/BD/16630/2004, at the CFTC, Lisboa University, Portugal. FCM is supported by CMAT, Univ. Minho, and FCT project PTDC/MAT/108921/2008. JPM also wishes to thank FCT for the plurianual running grant of CFTC.Peer reviewe

Modified Gravity and Cosmology: An Update by the CANTATA Network

General Relativity and the $\Lambda$CDM framework are currently the standard lore and constitute the concordance paradigm. Nevertheless, long-standing open theoretical issues, as well as possible new observational ones arising from the explosive development of cosmology the last two decades, offer the motivation and lead a large amount of research to be devoted in constructing various extensions and modifications. All extended theories and scenarios are first examined under the light of theoretical consistency, and then are applied to various geometrical backgrounds, such as the cosmological and the spherical symmetric ones. Their predictions at both the background and perturbation levels, and concerning cosmology at early, intermediate and late times, are then confronted with the huge amount of observational data that astrophysics and cosmology are able to offer recently. Theories, scenarios and models that successfully and efficiently pass the above steps are classified as viable and are candidates for the description of Nature. We list the recent developments in the fields of gravity and cosmology, presenting the state of the art, high-lighting the open problems, and outlining the directions of future research. Its realization is performed in the framework of the COST European Action "Cosmology and Astrophysics Network for Theoretical Advances and Training Actions"

Cosmology with the Laser Interferometer Space Antenna

The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational wave observations by LISA to probe the universe

Cosmology with the Laser Interferometer Space Antenna

The Laser Interferometer Space Antenna (LISA) has two scientific objectives of cosmological focus: to probe the expansion rate of the universe, and to understand stochastic gravitational-wave backgrounds and their implications for early universe and particle physics, from the MeV to the Planck scale. However, the range of potential cosmological applications of gravitational wave observations extends well beyond these two objectives. This publication presents a summary of the state of the art in LISA cosmology, theory and methods, and identifies new opportunities to use gravitational wave observations by LISA to probe the universe