The dynamics of apparent horizons in Robinson-Trautman spacetimes

We present an alternative scheme of finding apparent horizons based on spectral methods applied to Robinson-Trautman spacetimes. We have considered distinct initial data such as representing the spheroids of matter and the head-on collision of two non-rotating black holes. The evolution of the apparent horizon is presented. We have obtained in some cases a mass gap between the final Bondi and apparent horizon masses, whose implications were briefly commented in the light of the thermodynamics of black holes.Comment: 9 pages, 7 figure

Computational Complexity of interacting electrons and fundamental limitations of Density Functional Theory

One of the central problems in quantum mechanics is to determine the ground state properties of a system of electrons interacting via the Coulomb potential. Since its introduction by Hohenberg, Kohn, and Sham, Density Functional Theory (DFT) has become the most widely used and successful method for simulating systems of interacting electrons, making their original work one of the most cited in physics. In this letter, we show that the field of computational complexity imposes fundamental limitations on DFT, as an efficient description of the associated universal functional would allow to solve any problem in the class QMA (the quantum version of NP) and thus particularly any problem in NP in polynomial time. This follows from the fact that finding the ground state energy of the Hubbard model in an external magnetic field is a hard problem even for a quantum computer, while given the universal functional it can be computed efficiently using DFT. This provides a clear illustration how the field of quantum computing is useful even if quantum computers would never be built.Comment: 8 pages, 3 figures. v2: Version accepted at Nature Physics; differs significantly from v1 (including new title). Includes an extra appendix (not contained in the journal version) on the NP-completeness of Hartree-Fock, which is taken from v

Simulations of extensional flow in microrheometric devices

We present a detailed numerical study of the flow of a Newtonian fluid through microrheometric devices featuring a sudden contraction–expansion. This flow configuration is typically used to generate extensional deformations and high strain rates. The excess pressure drop resulting from the converging and diverging flow is an important dynamic measure to quantify if the device is intended to be used as a microfluidic extensional rheometer. To explore this idea, we examine the effect of the contraction length, aspect ratio and Reynolds number on the flow kinematics and resulting pressure field. Analysis of the computed velocity and pressure fields show that, for typical experimental conditions used in microfluidic devices, the steady flow is highly three-dimensional with open spiraling vortical structures in the stagnant corner regions. The numerical simulations of the local kinematics and global pressure drop are in good agreement with experimental results. The device aspect ratio is shown to have a strong impact on the flow and consequently on the excess pressure drop, which is quantified in terms of the dimensionless Couette and Bagley correction factors. We suggest an approach for calculating the Bagley correction which may be especially appropriate for planar microchannels

El recien nacido con dolor: el papel del equipo de enfermeria

It's a quantitative, descriptive and cross study conducted with the nurse team working in the field of neonatology at the three hospitals, Alfenas-MG. Aimed to describe the forms of pain assessment of the newborn used by nurse team and analyze the practice of nursing as pain management of neonates. Data were collected through a semi-structured formulary, from August to September 2008, of 42 nurses working. The analyze was performed using SPSS software using descriptive statistics and correlation test. It was observed that the respondents recognize that the newborn is capable of feeling pain and evaluated by physiological and behavioral changes and that there isn't pain assessment scales standardized in the institutions. For the management, carry out pharmacological and nonpharmacological interventions. There is need to train professionals contributing to the assessment and management of pain, promoting of holistic care of the neonate.Estudio cuantitativo, descriptivo y transversal realizado con profesionales de Enfermería que actúan en el área de Neonatología en los tres hospitales de Alfenas, Minas Gerais. Se objetivó describir las formas de evaluación del dolor del recién nacido utilizados por el personal de enfermería y analizar la práctica de la enfermería como el manejo del dolor del neonato. La recolección de datos fue hecha por medio de un formulario semiestructurado, entre agosto y septiembre de 2008, con 42 profesionales. El análisis fue hecho con el software SPSS, utilizando la estadística descriptiva y la prueba de correlación. Los entrevistados reconocen que el neonato es capaz de sentir dolor y esto se evalúa a través de alteraciones fisiológicas y de comportamiento, no hay utilización de escalas de evaluación del dolor estandarizadas en las instituciones. Para el manejo, realizan intervenciones farmacológicas y no farmacológicas. Hay necesidad de capacitar profesionales contribuyendo para la evaluación y manejo del dolor, para la promoción del cuidado integral al neonato.Estudo quantitativo, descritivo e transversal realizado com profissionais de enfermagem que atuam em neonatologia nos três hospitais de Alfenas-MG. Objetivou descrever as formas de avaliação de dor do recém-nascido utilizadas pela equipe de enfermagem e analisar a prática da enfermagem quanto ao manejo da dor do neonato. A coleta de dados foi feita por meio de formulário semiestruturado, de agosto a setembro de 2008, com 42 profissionais. A análise foi feita pelo software SPSS utilizando estatística descritiva e teste de correlação. Os entrevistados acreditam que o recém-nascido é capaz de sentir dor e a avaliam por meio de alterações fisiológicas e comportamentais, e que não há utilização de escalas de avaliação álgica padronizadas nas instituições. Para o manejo, realizam intervenções farmacológicas e não farmacológicas. Há necessidade de capacitar os profissionais, contribuindo para a avaliação e o manejo da dor, e promovendo o cuidado integral ao neonato.Universidade de São Paulo Escola de Enfermagem de Ribeirao Preto Departamento de Enfermagem Materno-infantil e Saude PublicaUniversidade Federal de São Paulo (UNIFESP) Departamento de Enfermagem Pediatrica Escola Paulista de EnfermagemUniversidade Federal de Alfenas Escola de Enfermagem Programa de Pos-graduacao em EnfermagemUniversidade de São Paulo Escola de Enfermagem de Ribeirao Preto Departamento de Enfermagem Geral e EspecializadaUniversidade Federal de Alfenas Escola de EnfermagemPrograma de Pos-graduacao em Enfermagem Programa de Pos-graduacao em EnfermagemEscola de Enfermagem Escola de EnfermagemUniversidade de São PauloUNIFESP, Depto. de Enfermagem Pediatrica Escola Paulista de Enfermagem (EPE)SciEL

The lumbrical muscle: a novel in situ system to evaluate adult skeletal muscle proteolysis and anticatabolic drugs for therapeutic purposes

Bergantin LB, Figueiredo LB, Godinho RO. the lumbrical muscle: a novel in situ system to evaluate adult skeletal muscle proteolysis and anticatabolic drugs for therapeutic purposes. J Appl Physiol 111: 1710-1718, 2011. First published September 15, 2011; doi:10.1152/japplphysiol.00586.2011.-The molecular regulation of skeletal muscle proteolysis and the pharmacological screening of anticatabolic drugs have been addressed by measuring tyrosine release from prepubertal rat skeletal muscles, which are thin enough to allow adequate in vitro diffusion of oxygen and substrates. However, the use of muscle at accelerated prepubertal growth has limited the analysis of adult muscle proteolysis or that associated with aging and neurodegenerative diseases. Here we established the adult rat lumbrical muscle (4/hindpaw; 8/rat) as a new in situ experimental model for dynamic measurement of skeletal muscle proteolysis. By incubating lumbrical muscles attached to their individual metatarsal bones in Tyrode solution, we showed that the muscle proteolysis rate of adult and aged rats (3-4 to 24 mo old) is 45-25% of that in prepubertal animals (1 mo old), which makes questionable the usual extrapolation of proteolysis from prepubertal to adult/senile muscles. While acute mechanical injury or 1- to 7-day denervation increased tyrosine release from adult lumbrical muscle by up to 60%, it was reduced by 20-28% after 2-h incubation with beta-adrenoceptor agonists, forskolin or phosphodiesterase inhibitor IBMX. Using inhibitors of 26S-proteasome (MG132), lysosome (methylamine), or calpain (E64/leupeptin) systems, we showed that ubiquitin-proteasome is accountable for 40-50% of total lumbrical proteolysis of adult, middle-aged, and aged rats. in conclusion, the lumbrical model allows the analysis of muscle proteolysis rate from prepubertal to senile rats. By permitting eight simultaneous matched measurements per rat, the new model improves similar protocols performed in paired extensor digitorum longus (EDL) muscles from prepubertal rats, optimizing the pharmacological screening of drugs for anticatabolic purposes.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Div Cellular Pharmacol, Dept Pharmacol, Escola Paulista Med, BR-04044020 São Paulo, BrazilUniversidade Federal de São Paulo, Div Cellular Pharmacol, Dept Pharmacol, Escola Paulista Med, BR-04044020 São Paulo, BrazilFAPESP: 05/59006-1FAPESP: 08/55988-2CNPq: 304602/2008-6Web of Scienc

An evaluation of enteral nutrition practices and nutritional provision in children during the entire length of stay in critical care

<b>Background</b> Provision of optimal nutrition in children in critical care is often challenging. This study evaluated exclusive enteral nutrition (EN) provision practices and explored predictors of energy intake and delay of EN advancement in critically ill children.<p></p> <b>Methods</b> Data on intake and EN practices were collected on a daily basis and compared against predefined targets and dietary reference values in a paediatric intensive care unit. Factors associated with intake and advancement of EN were explored.<p></p> <b>Results</b> Data were collected from 130 patients and 887 nutritional support days (NSDs). Delay to initiate EN was longer in patients from both the General Surgical and congenital heart defect (CHD) Surgical groups [Median (IQR); CHD Surgical group: 20.3 (16.4) vs General Surgical group: 11.4 (53.5) vs Medical group: 6.5 (10.9) hours; p <= 0.001]. Daily fasting time per patient was significantly longer in patients from the General Surgical and CHD Surgical groups than those from the Medical group [% of 24 h, Median (IQR); CHD Surgical group: 24.0 (29.2) vs General Surgical group: 41.7 (66.7) vs Medical group: 9.4 (21.9); p <= 0.001]. A lower proportion of fluids was delivered as EN per patient (45% vs 73%) or per NSD (56% vs 73%) in those from the CHD Surgical group compared with those with medical conditions. Protein and energy requirements were achieved in 38% and 33% of the NSDs. In a substantial proportion of NSDs, minimum micronutrient recommendations were not met particularly in those patients from the CHD Surgical group. A higher delivery of fluid requirements (p < 0.05) and a greater proportion of these delivered as EN (p < 0.001) were associated with median energy intake during stay and delay of EN advancement. Fasting (31%), fluid restriction (39%) for clinical reasons, procedures requiring feed cessation and establishing EN (22%) were the most common reasons why target energy requirements were not met.<p></p> <b>Conclusions</b> Provision of optimal EN support remains challenging and varies during hospitalisation and among patients. Delivery of EN should be prioritized over other "non-nutritional" fluids whenever this is possible.<p></p&gt

Modeling the quantum evolution of the universe through classical matter

It is well known that the canonical quantization of the Friedmann-Lema\^itre-Robertson-Walker (FLRW) filled with a perfect fluid leads to nonsingular universes which, for later times, behave as their classical counterpart. This means that the expectation value of the scale factor $(t)$ never vanishes and, as $t\to\infty$, we recover the classical expression for the scale factor. In this paper, we show that such universes can be reproduced by classical cosmology given that the universe is filled with an exotic matter. In the case of a perfect fluid, we find an implicit equation of state (EoS). We then show that this single fluid with an implict EoS is equivalent to two non-interacting fluids, one of them representing stiff matter with negative energy density. In the case of two non-interacting scalar fields, one of them of the phantom type, we find their potential energy. In both cases we find that quantum mechanics changes completely the configuration of matter for small values of time, by adding a fluid or a scalar field with negative energy density. As time passes, the density of negative energy decreases and we recover the ordinary content of the classical universe. The more the initial wave function of the universe is concentrated around the classical big bang singularity, the more it is necessary to add negative energy, since this type of energy will be responsible for the removal of the classical singularity.Comment: updated version as accepted by Gen. Relativ. Gravi

Caseous Calcification of the Mitral Annulus. A Review of Six Cases

Caseous calcification of the mitral annulus is a rare form of mitral annular calcification, whose etiology is not completely understood and which can lead to an erroneous diagnosis of intracardiac tumor. The authors describe the cases of six patients, five of them female, mean age 74.8 +/- 6.4 years (65-81). Four patients presented with heart failure, two with atrial fibrillation and five with hypertension. Round, echogenic images, 18-26 mm in their largest diameter with a central echolucent area, were identified by transthoracic echocardiography on the lateral and posterior segments of the mitral annulus. Severe mitral regurgitation was also found in four patients. Only three patients with severe mitral regurgitation and heart failure were operated on, and one patient refused surgical treatment. A caseous mass, similar to toothpaste, was obtained from the mitral annulus zone during surgery

Echocardiographic Variables Predictive of Appropriate Therapies for Ventricular Tachyarrhythmia in Patients Undergoing Combined Cardiac Resynchronization Therapy

INTRODUCTION: The significant risk of sudden arrhythmic death in patients with congestive heart failure and electromechanical ventricular dyssynchrony has led to increased use of combined cardiac resynchronization therapy defibrillator (CRT-D) devices. OBJECTIVES: To evaluate the echocardiographic variables in patients undergoing CRT-D that predict the occurrence of appropriate therapies (AT) for ventricular tachyarrhythmia. METHODS: We analyzed 38 consecutive patients (mean age 60 +/- 12 years, 63% male) with echocardiographic evaluation before and 6 months after CRT-D implantation. Patients with AT were identified in a mean follow-up of 471 +/- 323 days. A standard echocardiographic study was performed including tissue Doppler imaging (TDI). Responders were defined as patients with improvement in NYHA class of 25%. RESULTS: The responder rate was 74%, and the reverse remodeling rate was 55%. AT occurred in 21% of patients, who presented with greater left ventricular end-diastolic internal diameter (LVEDD) before implantation (86 +/- 8 vs. 76 +/- 11 mm, p = 0.03) and at 6 months (81 +/- 8 vs. 72 +/- 14 mm, p = 0.08), and increased left ventricular end-systolic internal diameter (66 +/- 14 vs. 56 +/- 14 mm, p = 0.03) and lower ejection fraction (24 +/- 6 vs. 34 +/- 14%, p = 0.08) at 6 months. In the group with AT, the responder rate was lower (38 vs. 83%, p = 0.03), without significant differences in reverse remodeling (38% for the AT group vs. 60%, p = 0.426) or in the other variables. By univariate analysis, predictors of AT were LVEDD before implantation and E' after implantation. Age, gender, ischemic etiology, use of antiarrhythmic drugs, reverse remodeling and the other echocardiographic parameters did not predict AT. In multivariate logistic regression analysis, both LVEDD before implantation (OR 1.24, 95% CI 1.04-1.48, p = 0.019) and postimplantation E' (OR 0.27, 95% CI 0.09-0.76, p = 0.014) remained as independent predictors of AT. CONCLUSIONS: In patients undergoing CRT-D, episodes of ventricular tachyarrhythmia occur with high incidence, independently of echocardiographic response, with LVEDD before implantation and E' after implantation as the only independent predictors of AT in the medium-term. These results highlight the importance of combined devices with defibrillation capability

Tidal Forces in Reissner-Nordström Spacetimes

We analyze the tidal forces produced in the spacetime of Reissner-Nordstr\"om black holes. We point out that the radial component of the tidal force changes sign just outside the event horizon if the charge-to-mass ratio is close to $1$ unlike in Schwarzschild spacetime of uncharged black holes, and that the angular component changes sign between the outer and inner horizons. We solve the geodesic deviation equations for radially falling bodies towards the charged black hole. We find, for example, that the radial component of the geodesic deviation vector starts decreasing inside the event horizon unlike in the Schwarzschild case