17 research outputs found
Nonlocal Equation of State in Anisotropic Static Fluid Spheres in General Relativity
We show that it is possible to obtain credible static anisotropic spherically
symmetric matter configurations starting from known density profiles and
satisfying a nonlocal equation of state. These particular types of equation of
state describe, at a given point, the components of the corresponding
energy-momentum tensor not only as a function at that point, but as a
functional throughout the enclosed configuration. To establish the physical
plausibility of the proposed family of solutions satisfying nonlocal equation
of state, we study the constraints imposed by the junction and energy
conditions on these bounded matter distributions.
We also show that it is possible to obtain physically plausible static
anisotropic spherically symmetric matter configurations, having nonlocal
equations of state\textit{,}concerning the particular cases where the radial
pressure vanishes and, other where the tangential pressures vanishes. The later
very particular type of relativistic sphere with vanishing tangential stresses
is inspired by some of the models proposed to describe extremely magnetized
neutron stars (magnetars) during the transverse quantum collapse.Comment: 21 pages, 1 figure, minor changes in the text, references added, two
new solutions studie
Space-time inhomogeneity, anisotropy and gravitational collapse
We investigate the evolution of non-adiabatic collapse of a shear-free
spherically symmetric stellar configuration with anisotropic stresses
accompanied with radial heat flux. The collapse begins from a curvature
singularity with infinite mass and size on an inhomogeneous space-time
background. The collapse is found to proceed without formation of an even
horizon to singularity when the collapsing configuration radiates all its mass
energy. The impact of inhomogeneity on various parameters of the collapsing
stellar configuration is examined in some specific space-time backgrounds.Comment: To appear in Gen. Relativ. Gra
Spherically symmetric dissipative anisotropic fluids: A general study
The full set of equations governing the evolution of self--gravitating
spherically symmetric dissipative fluids with anisotropic stresses is deployed
and used to carry out a general study on the behaviour of such systems, in the
context of general relativity. Emphasis is given to the link between the Weyl
tensor, the shear tensor, the anisotropy of the pressure and the density
inhomogeneity. In particular we provide the general, necessary and sufficient,
condition for the vanishing of the spatial gradients of energy density, which
in turn suggests a possible definition of a gravitational arrow of time. Some
solutions are also exhibited to illustrate the discussion.Comment: 28 pages Latex. To appear in Phys.Rev.
Nature of singularity formed by the gravitational collapse in Husain space-time with electromagnetic field and scalar field
In this work, we have investigated the outcome of gravitational collapse in
Husain space-time in the presence of electro-magnetic and a scalar field with
potential. In order to study the nature of the singularity, global behavior of
radial null geodesics have been taken into account. The nature of singularities
formed has been thoroughly studied for all possible variations of the
parameters. These choices of parameters has been presented in tabular form in
various dimensions. It is seen that irrespective of whatever values of the
parameters chosen, the collapse always results in a naked singularity in all
dimensions. There is less possibility of formation of a black hole. Hence this
work is a significant counterexample of the cosmic censorship hypothesis.Comment: 9 pages, 19 figure
Collapsing shear-free perfect fluid spheres with heat flow
A global view is given upon the study of collapsing shear-free perfect fluid
spheres with heat flow. We apply a compact formalism, which simplifies the
isotropy condition and the condition for conformal flatness. This formalism
also presents the simplest possible version of the main junction condition,
demonstrated explicitly for conformally flat and geodesic solutions. It gives
the right functions to disentangle this condition into well known differential
equations like those of Abel, Riccati, Bernoulli and the linear one. It yields
an alternative derivation of the general solution with functionally dependent
metric components. We bring together the results for static and time- dependent
models to describe six generating functions of the general solution to the
isotropy equation. Their common features and relations between them are
elucidated. A general formula for separable solutions is given, incorporating
collapse to a black hole or to a naked singularity.Comment: 26 page
Transitions of cardio-metabolic risk factors in the Americas between 1980 and 2014
Describing the prevalence and trends of cardiometabolic risk factors that are associated with non-communicable diseases (NCDs) is crucial for monitoring progress, planning prevention, and providing evidence to support policy efforts. We aimed to analyse the transition in body-mass index (BMI), obesity, blood pressure, raised blood pressure, and diabetes in the Americas, between 1980 and 2014
Rising rural body-mass index is the main driver of the global obesity epidemic in adults
Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities 1,2 . This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity 3�6 . Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 of the global rise in mean BMI from 1985 to 2017�and more than 80 in some low- and middle-income regions�was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing�and in some countries reversal�of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories. © 2019, The Author(s)
Protein enrichment of Opuntia ficus-indica using Kluyveromyces marxianus in solid-state fermentation
Opuntia ficus-indica is used in animal feed but has a low protein content (above 4%) in comparison to high-quality forage (above 16%). It is necessary to develop technologies that improve the nutrimental value of Opuntia ficus-indica through the process of solid-state fermentation (SSF). Therefore, the objective of this study was to evaluate the changes in the chemical composition of Opuntia ficus-indica during the SSF with the yeast Kluyveromyces marxianus ITD00262. Kluyveromyces marxianus ITD00262 was grown in glucose, peptone, yeast (GPY) broth, at 28 °C and pH 4.8 for 12 h. Opuntia ficusindica was incubated in SSF at 28 °C without inoculation (T1) or inoculated with K. marxianus ITD00262 (T2). Fermented samples of Opuntia ficus-indica were dried, and the dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (LIGN) and in vitro dry matter digestibility (IVDMD) contents were ascertained. Data were analyzed with a completely randomized design with a factorial arrangement of 2×6. A decrease of 11% in DM was observed for T1 compared with T2 at 48 h of fermentation. A 300% increase in PC content was observed for T2 at 120 h of fermentation. The DMIVD was increased by 3%, whereas the values of NDF and ADF decreased by 18% in T2. According to our results, it is confirmed that the use of K. marxianus in the SSF of Opuntia ficus-indica has a positive effect and improves the nutrimental quality of this forage.Opuntia ficus-indica es utilizado en la alimentación animal, a pesar de su bajo contenido de proteínas (4%) comparado con forrajes de alta calidad (16%). Es necesario desarrollar tecnologías que permitan incrementar el valor nutrimental de O. ficus-indica, mediante procesos como la fermentación en estado sólido (FES). Por lo que el objetivo de este trabajo fue evaluar los cambios en la composición química de O. ficus-indica durante la FES al ser inoculado con K. marxianus ITD00262, para esto la cepa se activó en caldo de Glucosa peptona, extracto de levadura (GPY), a 28°C y pH de 4.8, el proceso de fermentación consistió de dos tratamientos, el primero sin inoculación de K. marxianus (T1), el segundo inoculando K marxianus (T2). Las muestras de O. ficus-indica fermentadas fueron secadas, y se les determinó los contenidos de materia seca (MS), proteína cruda (PC), fibra detergente neutra (FDN), fibra acido detergente (FDA), lignina (LIGN), digestibilidad in vitro de materia seca (IVDMD). Los datos fueron analizados con un arreglo factorial de 2×6. Se observó una disminución en la MS, el cual fue 11% menor para T1 comparado con T2 a las 48 h de fermentación. El contenido de PC, se incrementó 300% en T2 a las 120 h de fermentación. La DIVMS aumentó 3% mientras que los valores de FDN y FDA disminuyeron 18% en T2. De acuerdo con nuestros resultados, se confirma que el uso de K. marxianus en la FES de O. ficusindica, tiene un efecto positivo porque incrementa la calidad nutritiva de este forraje
Physiological characterization of two native yeasts in pure and mixed culture using fermentations of agave juice
Yeast cells are subjected to diverse environmental conditions during the alcoholic fermentation of agave juice, causing different kinetic behaviors. Agave juice was used as culture medium to evaluate the kinetic behavior of Saccharomyces cerevisiae ITD-00185 and Torulaspora delbrueckii ITD-00014a, as pure and mixed cultures, under different inoculum sizes (1×105, 1×106, 1×107 and 1×108 cells mL-1), and combined pH levels (3.5, 4.0 and 4.5) and temperatures (18 °C, 28 °C and 38 °C). Saccharomyces cerevisiae displayed high fermentation capacities at all inoculum concentrations assayed. However, T. delbrueckii required a high inoculum concentration (≥1×107 cells mL-1) to perform at fermentation levels similar to S. cerevisiae. Low temperatures (18 °C) slowed fermentation, while high temperatures (38 °C) adversely affected the development of the yeast strains, especially T. delbrueckii. The best temperature was 28 °C in all fermentations. The pH level had a strong effect on the performance of the coculture, since the fermentation kinetics suggested a synergistic effect at pH 4.5, while an antagonistic effect was postulated at pH 3.5. In all of the mixed culture cases, a positive effect at 28 °C, especially at pH 4.0 and 4.5, was demonstrated by greater levels of sugar consumption and ethanol production (~20%, p<0.05) compared to fermentations of the S. cerevisiae monoculture. The coculture results allow us to postulate that a complex interaction exists between the two yeasts, which could be synergistic or antagonistic, as the environmental conditions change.Las levaduras se someten a diversas condiciones ambientales durante la fermentación alcohólica de jugo de agave, causando diferentes comportamientos cinéticos. Se utilizó jugo de agave como medio de cultivo para evaluar el comportamiento cinético de Saccharomyces cerevisiae ITD-00185 y Torulaspora delbrueckii ITD-00014a, en cultivos puros y mezclados, en diferentes condiciones de tamaño de inóculo (1×105, 1×106, 1×107 y 1×108 células ml-1) y combinaciones de pH (3.5, 4.0 y 4.5) y temperatura (18 °C, 28 °C y 38 °C). Saccharomyces cerevisiae mostró alta capacidad fermentativa en todas las concentraciones de inóculo. Torulaspora delbrueckii requirió alta concentración de inóculo (≥1×107 células mL-1) para fermentar como S. cerevisiae. A 18 °C se retardó la fermentación, mientras que a 38 °C se afectó negativamente al desarrollo de las levaduras, especialmente T. delbrueckii. La fermentación fue vigorosa para ambas levaduras a 28 °C. El pH tuvo un fuerte efecto sobre el rendimiento del co-cultivo, sugiriendo un efecto sinérgico a pH 4.5 y efecto antagónico a pH 3.5. Para cultivo mixto se observó un efecto positivo a 28 °C, especialmente a pH 4.0 y 4.5, demostrando mejor consumo de azúcar y producción de etanol (~ 20%, p <0,05) comparado con el monocultivo de S. cerevisiae. Los resultados globales permiten postular una interacción compleja entre las dos levaduras, que puede ser sinérgica o antagónica, según las condiciones ambientales
Preliminary clinical experience of the systemic use of 153Sm-EDTMP as a pain palliation agent in arthrosis and as an option for bone scanning in patients with bone metastases
Introducción: Muchos pacientes con artrosis tienen efectos secundarios producidos por los tratamientos convencionales. Estos pacientes son candidatos para tratamiento paliativo del dolor
con 153Sm-EDTMP. Los pacientes con metástasis ósea, por lo general, requieren un rastreo utilizando ‘Tc-MDP, antes del tratamiento paliativo con 3Sm-EDTMP. Este trabajo tiene 2 objetivos: 1) evaluar el uso de 153Sm-EDTMP como alternativa en Los procedimientos de rastreo óseo
en pacientes con metástasis ósea y, 2) si el 153Sm-EDTMP es captado en la articulación lesionada
con artrosis, entonces se evalúa el uso eficiente y seguro de la administración sistémica de este
radiofármaco, para Ia paliación del dolor por artrosis.
Métodos y materiales: Una muestra no probabilística, de oportunidad y secuencial de 10 pacientes
con artrosis fue seleccionada, así como, un paciente con metástasis ósea secundaria a cáncer de
próstata. En Los 11 pacientes se realizaron gammagrafias óseas con Los radiofármacos “Tc-MDP y
ls3mEDTMP, para comparar [a calidad de imagen y sitios de captación. En los pacientes con artrosis
se administró por vía sistémica una dosis terapéutica de ‘Sm-EDTMP para la paliación del dolor. Se
realizaron perfiles hematológicos con el fin de garantizar La seguridad de la médula ósea. La evolución del dolor y de la motilidad se utilizó para evaluar La eficacia analgésica 3Sm-EDTMR
Resultados y conclusión: La calidad de imagen obtenida en Los 11 pacientes con ‘3Snì-EDTMP es similar desde el punto de vista clínico, a Ias obtenidas con ‘“Tc-MDR EL 3Sm-EDTMP es captado por las articulaciones con artrosis y metástasis óseas. La dosis terapéutica de 1’Sm-EDTMP administrada
por vía intravenosa fue bien tolerada por Ia médula ósea en todos Los pacientes, así como hubo un efecto analgésico, por lo que mejoró la motilidad y la calidad de vida en los pacientes con artrosis.Introduction: Many patients with arthrosis have side effects produced by conventional
treatments. These patients are candidates for pain palliation with 153Sm-EDTMP. Patients with
cancer bone metastases usuaLly require a bone scanning procedure using ““Tc-MDP, prior to
treatment through 153Sm-EDTMP. This work has two aims. Firstly, to assess the use of 153Sm-
EDTMP as an alternative in bone scanning procedures in patients with bones metastases. Se
condly, if the 153Sm-EDTMP is uptaken by the arthrosis injured joint, then the efficient and safe
use of the systemic administration of this radiopharmaceutical is evaluated for pain palliation.
Methods and materials: A non-probabilistic, of opportunity and sequential sample of 10 patients
with arthrosis was selected, as well as, one patient with bone metastasis secondary to prostate
cancer. In the li patients, bone scans were performed using both radiopharmaceuticals “‘T1Tc-
MDP and 153Sm-EDTMP to compare image quality and uptake sites. In patients with arthrosis a
therapeutic dose with ‘53Sm-EDTMP was systemically administered for pain palliation. Hemato
logic profiles were performed in order to assure security to the bone marrow. Pain and motility
evaluations were carried out to assess the Sm-EDTMP analgesic efficacy.
Results and conclusion: The Image qualities obtained with 13Sm-EDTMP are similar from the
cLinical point of view to those obtained with ““Tc-MDR Sm-EDTMP is captured by joints with
arthrosis and bone metastases. Therapeutic doses of 1Sm-EDTMP intravenously administered
are well tolerated by the bone marrow, while an analgesic effect is present which improves
motility and quality of Life in patients with arthrosis