scholarly journals Violation of the Dominant Energy Condition in Geometrodynamics

Symmetry ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 400
Author(s):  
Vladimir Lasukov
Keyword(s):  
Black Holes ◽  
Dark Energy ◽  
Energy Condition ◽  
Dominant Energy Condition ◽  
Isotropic Energy ◽  
Cosmological Singularity ◽  
Dominant Condition ◽  
Field Theoretical Model ◽  
Over Time

It is shown that in Einstein’s theory and in the theory of gravity with Logunov constraints, there is a field-theoretical model of dark energy that is consistent with the observational data indicating that the Hubble value increases over time. In the developed model of dark energy, the isotropic energy dominant condition is violated. It solves the problem of the cosmological singularity and the singularity of “black holes”. The compact configuration of the scalar field can generate a flux of particles by the pairs of particles production mechanism from the vacuum by a field of barrier and in the process of transformation of thermal energy (Hawking radiation) and acceleration energy into radiation. The scalars can play the role of the so-called “black holes” with no singularity inside themselves.

WIGGLY COSMIC STRINGS ACCRETE DARK ENERGY

2006 ◽  
Vol 15 (04) ◽  
pp. 603-613 ◽  
Author(s):  
PEDRO F. GONZÁLEZ-DÍAZ ◽  
JOSÉ A. JIMÉNEZ MADRID
Keyword(s):  
Dark Energy ◽  
Energy Density ◽  
Cosmic Strings ◽  
Energy Condition ◽  
Phantom Energy ◽  
Dominant Energy Condition ◽  
Final State ◽  
Cylindrically Symmetric ◽  
Energy Models ◽  
Maximum Value

This paper deals with a study of the cylindrically symmetric accretion of dark energy with equation of state p = wρ onto wiggly straight cosmic strings, interpreting that the accreted energy only contributes the extent of the wiggliness, but consistently leaves invariant the unperturbed line density μ0. We have obtained that when w > -1, the perturbed linear energy density in the string core gradually increases tending to a finite maximum value as time increases, for all considered dark energy models. Where the dominant energy condition is violated, all such models predict a steady decreasing of the perturbed linear energy density μ of the cosmic strings as phantom energy is being accreted. The final state of the string after such an accretion process is a wiggleless defect. It is argued however, that if accreation of phantom energy would proceed by successive quantum steps, then the defect would continue losing perturbed linear energy density beyond μ0, until a minimum nonzero value which can be smaller than that corresponding to the unperturbed string.

EXISTENCE OF BLACK HOLES IN FRIEDMANN–ROBERTSON–WALKER UNIVERSE DOMINATED BY DARK ENERGY

2007 ◽  
Vol 22 (22) ◽  
pp. 1663-1676 ◽  
Author(s):  
ZHONG-HENG LI ◽  
ANZHONG WANG
Keyword(s):  
Black Holes ◽  
Dark Energy ◽  
Energy Condition ◽  
Strong Energy Condition ◽  
Frw Universe ◽  
Strong Energy ◽  
Friedmann Robertson Walker

We study the existence of black holes in a homogeneous and isotropic expanding Friedmann–Robertson–Walker (FRW) universe dominated by dark energy. We show that black holes exist in such a universe by considering some specific McVittie solutions, for which the FRW background satisfies the weak (but not the strong) energy condition.

Raza, ciencia, sociedad

2015 ◽  
Vol 2 (4) ◽  
Author(s):  
Peter Wade
Keyword(s):  
Cultural Discourse ◽  
Human Biology ◽  
Science And Society ◽  
Race Science ◽  
And Behavior ◽  
Over Time

<p class="p1"><span class="s1"><strong>Resumen </strong></span>| En este trabajo quiero presentar una cronología convencional del concepto raza que marca un movimiento en el cual raza cambia de ser una idea basada en la cultura y el medio ambiente, a ser algo biológico, inflexible y determinante, para luego volver a ser una noción que habla de la cultura<span class="s2"><strong>.</strong></span>Resumo cómo la idea de raza ha cambiado a través del tiempo, mirando necesariamente el rol que ha desempeñado la ciencia, y enfocando los diferentes discursos de índole <em>natural-cultural </em>sobre los cuerpos, el medio ambiente y el comportamiento, en los cuales las dimensiones culturales y naturales siempre coexisten<span class="s2"><strong>.</strong></span>“La naturaleza” no puede ser entendida solamente como “la biología” y ni la naturaleza ni la biología necesariamente implican sólo el determinismo, la fijeza y la inmutabilidad Estar abiertos a la coexistencia de la cultura y la naturaleza y a la mutabilidad de la naturaleza nos permite ver mejor el ámbito de acción del pensamiento racial.</p><p class="p1"><strong><em>Race, Science and Society</em></strong></p><p class="p1"> </p><p class="p2"><span class="s1"><strong>Abstract </strong></span>| In this article I present and critique a standard chronology of race as, first, a concept rooted in culture and environment, and later in human biology and determinism, and finally back to culture alone<span class="s2"><strong><em>.</em></strong></span>I will outline changing understandings of race over time, with some attention to the role of science, broadly understood, and on the continuing but changing character of race as a natural-cultural discourse about organic bodies, environments and behavior, in which both cultural and natural dimensions always co-exist<span class="s2"><strong><em>.</em></strong></span>“Nature” is not to be understood simply as “biology,” and neither nature nor biology necessarily imply the fixity and determination that they are often assumed nowadays to involve<span class="s2"><strong><em>.</em></strong></span>Being open to the co-existence of culture and nature and the mutability of the latter allows us to better comprehend the whole range of action of racial thinking.</p>

Biopsychosocial Patterning of Multimorbidity and Its Consequences

2018 ◽  
pp. 220-236
Author(s):  
Elliot Friedman ◽  
Beth LeBreton ◽  
Lindsay Fuzzell ◽  
Elizabeth Wehrpsann
Keyword(s):  
Quality Of Life ◽  
Older Adults ◽  
Functional Outcomes ◽  
The United States ◽  
Chronic Medical Conditions ◽  
Quality Of Life Research ◽  
Increased Risk ◽  
Over Time

By many estimates the majority of adults over age 65 have two or more chronic medical conditions (multimorbidity) and are consequently at increased risk of adverse functional outcomes. Nonetheless, many older adults with multimorbidity are able to maintain high levels of function and retain good quality of life. Research presented here is designed to understand the influences that help ensure better functional outcomes in these older adults. This chapter presents findings that draw on data from the Midlife in the United States study. The independent and interactive contributions of diverse factors to multimorbidity and changes in multimorbidity over time are reviewed. The degree that multimorbidity increases risk of cognitive impairment and disability is examined. The role of inflammation as a mediator is considered. Multimorbidity is increasingly the norm for older adults, so better understanding of factors contributing to variability in multimorbidity-related outcomes can lead to improved quality of life.

scholarly journals Learning by Doing: The Use of Distance, Corners and Length in Rewarded Geometric Tasks by Zebrafish (Danio rerio)

Animals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 2001
Author(s):  
Greta Baratti ◽  
Angelo Rizzo ◽  
Maria Elena Miletto Petrazzini ◽  
Valeria Anna Sovrano
Keyword(s):  
Danio Rerio ◽  
Three Dimensional ◽  
Reference Memory ◽  
Spatial Abilities ◽  
Learning By Doing ◽  
Surface Distance ◽  
Extended Surfaces ◽  
Unequal Length ◽  
Over Time

Zebrafish spontaneously use distance and directional relationships among three-dimensional extended surfaces to reorient within a rectangular arena. However, they fail to take advantage of either an array of freestanding corners or an array of unequal-length surfaces to search for a no-longer-present goal under a spontaneous cued memory procedure, being unable to use the information supplied by corners and length without some kind of rewarded training. The present study aimed to tease apart the geometric components characterizing a rectangular enclosure under a procedure recruiting the reference memory, thus training zebrafish in fragmented layouts that provided differences in surface distance, corners, and length. Results showed that fish, besides the distance, easily learned to use both corners and length if subjected to a rewarded exit task over time, suggesting that they can represent all the geometrically informative parts of a rectangular arena when consistently exposed to them. Altogether, these findings highlight crucially important issues apropos the employment of different behavioral protocols (spontaneous choice versus training over time) to assess spatial abilities of zebrafish, further paving the way to deepen the role of visual and nonvisual encodings of isolated geometric components in relation to macrostructural boundaries.

scholarly journals Effects of Dysbiosis and Dietary Manipulation on the Digestive Microbiota of a Detritivorous Arthropod

2021 ◽  
Vol 9 (1) ◽  
pp. 148
Author(s):  
Marius Bredon ◽  
Elisabeth Depuydt ◽  
Lucas Brisson ◽  
Laurent Moulin ◽  
Ciriac Charles ◽  
...  
Keyword(s):  
Crucial Role ◽  
Structure And Function ◽  
Ecological Interactions ◽  
Dietary Manipulation ◽  
Biotic Factors ◽  
Abiotic And Biotic Factors ◽  
And Function ◽  
Multicellular Organisms ◽  
Over Time

The crucial role of microbes in the evolution, development, health, and ecological interactions of multicellular organisms is now widely recognized in the holobiont concept. However, the structure and stability of microbiota are highly dependent on abiotic and biotic factors, especially in the gut, which can be colonized by transient bacteria depending on the host’s diet. We studied these impacts by manipulating the digestive microbiota of the detritivore Armadillidium vulgare and analyzing the consequences on its structure and function. Hosts were exposed to initial starvation and then were fed diets that varied the different components of lignocellulose. A total of 72 digestive microbiota were analyzed according to the type of the diet (standard or enriched in cellulose, lignin, or hemicellulose) and the period following dysbiosis. The results showed that microbiota from the hepatopancreas were very stable and resilient, while the most diverse and labile over time were found in the hindgut. Dysbiosis and selective diets may have affected the host fitness by altering the structure of the microbiota and its predicted functions. Overall, these modifications can therefore have effects not only on the holobiont, but also on the “eco-holobiont” conceptualization of macroorganisms.

The Internet according to kids

2002 ◽  
Vol 3 (2) ◽  
pp. 45-52
Author(s):  
Jorian Clarke
Keyword(s):  
Parental Involvement ◽  
Mobile Phones ◽  
Online Shopping ◽  
Online Banking ◽  
Internet Usage ◽  
The Internet ◽  
The Future ◽  
Child Friendly ◽  
Over Time

Describes a six‐year study of children’s Internet usage which shows how preferences and habits have changed over time; this was conducted by SpectraCom Inc and Circle 1 network. Explains the research methodology and the objectives, which were to identify trends in the amount of time spent by children online now and in future, their opinions about the future role of the Internet in society and the future of e‐commerce, and parents’ roles in children’s online activities. Concludes that there is need for a more child‐friendly content in Internet sites and for more parental involvement, that children will be influential in the market for alternative devices like mobile phones, that online shopping is likely to flourish, and that children have a growing interest in online banking.

The Role of Mechanical Tension in Neurons

2010 ◽  
Vol 1274 ◽  
Author(s):  
Taher Saif ◽  
Jagannathan Rajagopalan ◽  
Alireza Tofangchi
Keyword(s):  
Mechanical Response ◽  
Mechanical Forces ◽  
Active Tension ◽  
Mechanical Tension ◽  
Deformation Response ◽  
Linear Force ◽  
Tension Regulation ◽  
Over Time

AbstractWe used high resolution micromechanical force sensors to study the in vivo mechanical response of embryonic Drosophila neurons. Our experiments show that Drosophila axons have a rest tension of a few nN and respond to mechanical forces in a manner characteristic of viscoelastic solids. In response to fast externally applied stretch they show a linear force-deformation response and when the applied stretch is held constant the force in the axons relaxes to a steady state value over time. More importantly, when the tension in the axons is suddenly reduced by releasing the external force the neurons actively restore the tension, sometimes close to their resting value. Along with the recent findings of Siechen et al (Proc. Natl. Acad. Sci. USA 106, 12611 (2009)) showing a link between mechanical tension and synaptic plasticity, our observation of active tension regulation in neurons suggest an important role for mechanical forces in the functioning of neurons in vivo.

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