scholarly journals Cosmological hyperfluids, torsion and non-metricity

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Damianos Iosifidis
Keyword(s):  
Conservation Laws ◽  
Previous Model ◽  
Covariant Form ◽  
Future Directions ◽  
Affine Spaces ◽  
Cosmological Principle ◽  
Friedmann Equations ◽  
Flrw Universe ◽  
Novel Model

AbstractWe develop a novel model for cosmological hyperfluids, that is fluids with intrinsic hypermomentum that induce spacetime torsion and non-metricity. Imposing the cosmological principle to metric-affine spaces, we present the most general covariant form of the hypermomentum tensor in an FLRW Universe along with its conservation laws and therefore construct a novel hyperfluid model for cosmological purposes. Extending the previous model of the unconstrained hyperfluid in a cosmological setting we establish the conservation laws for energy–momentum and hypermomentum and therefore provide the complete cosmological setup to study non-Riemannian effects in Cosmology. With the help of this we find the forms of torsion and non-metricity that were earlier reported in the literature and also obtain the most general form of the Friedmann equations with torsion and non-metricity. We also discuss some applications of our model, make contact with the known results in the literature and point to future directions.

scholarly journals On the Splitting of the Einstein Field Equations with respect to General (1+3) Threading of Spacetime

2016 ◽  
Vol 2016 ◽  
pp. 1-15
Author(s):  
Aurel Bejancu ◽  
Hani Reda Farran
Keyword(s):  
Conservation Laws ◽  
Perfect Fluid ◽  
Energy Momentum Tensor ◽  
Momentum Tensor ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Friedmann Equations ◽  
Flrw Universe

Based on general (1+3) threading of the spacetime (M,g), we obtain a new and simple splitting of both the Einstein field equations (EFE) and the conservation laws in (M,g). As an application, we obtain the splitting of EFE in an almost FLRW universe with energy-momentum tensor of a perfect fluid. In particular, we state the perturbation Friedmann equations in an almost FLRW universe.

A Novel Model for Advancing Sexual Assault Education and Prevention on Campus

2019 ◽  
Vol 46 (4) ◽  
pp. 306-311
Author(s):  
Courtenay E. Cavanaugh
Keyword(s):  
Sexual Assault ◽  
Service Learning ◽  
Interpersonal Violence ◽  
Intervention Program ◽  
Sexual Assault Prevention ◽  
Future Directions ◽  
Psychology Courses ◽  
Psychology Course ◽  
Assault Prevention ◽  
Novel Model

Teachers of psychology have been called to both educate college students about interpersonal violence (e.g., sexual assault) and use service learning. However, few models exist for how teachers may simultaneously address both of these calls. This article describes a service-learning course in psychology that integrated an evidence-based, bystander intervention program (BIP) into it in order to provide students with both sexual assault education and roles for advancing sexual assault prevention on campus. Sixteen students in an undergraduate psychology course watched TakeCare, a video shown to improve students’ positive bystander behavior to prevent sexual assault and then facilitated delivery of TakeCare to 156 other students on campus. This course illustrates a novel model for advancing sexual assault education and prevention on campus, and the model may be used in other psychology courses. Future directions for implementing and evaluating this model are described.

scholarly journals The cosmology of quadratic torsionful gravity

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
Damianos Iosifidis ◽  
Lucrezia Ravera
Keyword(s):  
Conservation Laws ◽  
Equations Of Motion ◽  
Analytic Solutions ◽  
Gravity Theory ◽  
Gravitational Action ◽  
Independent Variables ◽  
Friedmann Equations ◽  
Exact Analytic Solutions ◽  
Cartan Theory

AbstractWe study the cosmology of a quadratic metric-compatible torsionful gravity theory in the presence of a perfect hyperfluid. The gravitational action is an extension of the Einstein–Cartan theory given by the usual Einstein–Hilbert contribution plus all the admitted quadratic parity even torsion scalars and the matter action also exhibits a dependence on the connection. The equations of motion are obtained by regarding the metric and the metric-compatible torsionful connection as independent variables. We then consider a Friedmann–Lemaître–Robertson–Walker background, analyze the conservation laws, and derive the torsion modified Friedmann equations for our theory. Remarkably, we are able to provide exact analytic solutions for the torsionful cosmology.

scholarly journals Myocardial slices come to age: an intermediate complexity in vitro cardiac model for translational research

2019 ◽  
Vol 116 (7) ◽  
pp. 1275-1287 ◽  
Author(s):  
Fotios G Pitoulis ◽  
Samuel A Watson ◽  
Filippo Perbellini ◽  
Cesare M Terracciano
Keyword(s):  
Heart Tissue ◽  
Tissue Slices ◽  
Future Directions ◽  
Thin Sections ◽  
Research Systems ◽  
Cardiac Model ◽  
Technological Developments ◽  
Whole Heart ◽  
Novel Model

Abstract Although past decades have witnessed significant reductions in mortality of heart failure together with advances in our understanding of its cellular, molecular, and whole-heart features, a lot of basic cardiac research still fails to translate into clinical practice. In this review we examine myocardial slices, a novel model in the translational arena. Myocardial slices are living ultra-thin sections of heart tissue. Slices maintain the myocardium’s native function (contractility, electrophysiology) and structure (multicellularity, extracellular matrix) and can be prepared from animal and human tissue. The discussion begins with the history and current advances in the model, the different interlaboratory methods of preparation and their potential impact on results. We then contextualize slices’ advantages and limitations by comparing it with other cardiac models. Recently, sophisticated methods have enabled slices to be cultured chronically in vitro while preserving the functional and structural phenotype. This is more timely now than ever where chronic physiologically relevant in vitro platforms for assessment of therapeutic strategies are urgently needed. We interrogate the technological developments that have permitted this, their limitations, and future directions. Finally, we look into the general obstacles faced by the translational field, and how implementation of research systems utilizing slices could help in resolving these.

A covariant form for the complete set of first-order electromagnetic conservation laws

1994 ◽  
Vol 320 (1-2) ◽  
pp. 96-98 ◽  
Author(s):  
I.Yu. Krivsky ◽  
V.M. Simulik ◽  
Z.Z. Torich
Keyword(s):  
Conservation Laws ◽  
Covariant Form ◽  
First Order ◽  
Complete Set

Intestinal organoids: a model to study the role of microbiota in the colonic tumor microenvironment

2020 ◽  
Vol 15 (16) ◽  
pp. 1583-1594
Author(s):  
Harika Nalluri ◽  
Subbaya Subramanian ◽  
Christopher Staley
Keyword(s):  
Experimental Models ◽  
Microbial Composition ◽  
Future Directions ◽  
Complex Interactions ◽  
Microbiome Research ◽  
Metabolic Interactions ◽  
Crc Management ◽  
The Relationship ◽  
Novel Model

Colorectal cancer (CRC) is the third most common cause of cancer worldwide. Recent studies have suggested that a dysbiotic shift in the intestinal microbial composition of CRC patients influences tumorigenesis. Gut microbes are known to be integral for intestinal homeostasis; however, the mechanisms by which they impact CRC are unclear. Further knowledge about these complex interactions may guide future CRC management. Thus, it is crucial to establish high-quality experimental models to understand the relationship between host, tumor, microbiota and their metabolic interactions. In this review, we highlight the significance of intestinal microbiota and their metabolites in CRC, challenges with current experimental models, advantages and limitations of organoid culture and future directions of this novel model system in CRC-associated microbiome research.

How Much Time Do People With Aphasia Need to Respond During Picture Naming? Estimating Optimal Response Time Cutoffs Using a Multinomial Ex-Gaussian Approach

2020 ◽  
Vol 63 (2) ◽  
pp. 599-614 ◽  
Author(s):  
William S. Evans ◽  
William D. Hula ◽  
Yina Quique ◽  
Jeffrey J. Starns
Keyword(s):  
Response Time ◽  
Picture Naming ◽  
Language Disorder ◽  
Processing Efficiency ◽  
Future Directions ◽  
Assessment And Treatment ◽  
Novel Model ◽  
Accuracy Performance ◽  
Naming Performance ◽  
Rt Distributions

Purpose Aphasia is a language disorder caused by acquired brain injury, which generally involves difficulty naming objects. Naming ability is assessed by measuring picture naming, and models of naming performance have mostly focused on accuracy and excluded valuable response time (RT) information. Previous approaches have therefore ignored the issue of processing efficiency, defined here in terms of optimal RT cutoff, that is, the shortest deadline at which individual people with aphasia produce their best possible naming accuracy performance. The goals of this study were therefore to (a) develop a novel model of aphasia picture naming that could accurately account for RT distributions across response types; (b) use this model to estimate the optimal RT cutoff for individual people with aphasia; and (c) explore the relationships between optimal RT cutoff, accuracy, naming ability, and aphasia severity. Method A total of 4,021 naming trials across 10 people with aphasia were scored for accuracy and RT onset. Data were fit using a novel ex-Gaussian multinomial RT model, which was then used to characterize individual optimal RT cutoffs. Results Overall, the model fitted the empirical data well and provided reliable individual estimates of optimal RT cutoff in picture naming. Optimal cutoffs ranged between approximately 5 and 10 s, which has important implications for assessment and treatment. There was no direct relationship between aphasia severity, naming RT, and optimal RT cutoff. Conclusion The multinomial ex-Gaussian modeling approach appears to be a promising and straightforward way to estimate optimal RT cutoffs in picture naming in aphasia. Limitations and future directions are discussed.

On Future Directions in Pathology

1982 ◽  
Vol 40 ◽  
pp. 274-277
Author(s):  
Benjamin F. Trump ◽  
Irene K. Berezesky ◽  
Raymond T. Jones
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Clinical Pathology ◽  
Future Directions ◽  
Diagnostic Pathology ◽  
The Past ◽  
Transmission Electron ◽  
Organ Systems ◽  
The Many

The role of electron microscopy and associated techniques is assured in diagnostic pathology. At the present time, most of the progress has been made on tissues examined by transmission electron microscopy (TEM) and correlated with light microscopy (LM) and by cytochemistry using both plastic and paraffin-embedded materials. As mentioned elsewhere in this symposium, this has revolutionized many fields of pathology including diagnostic, anatomic and clinical pathology. It began with the kidney; however, it has now been extended to most other organ systems and to tumor diagnosis in general. The results of the past few years tend to indicate the future directions and needs of this expanding field. Now, in addition to routine EM, pathologists have access to the many newly developed methods and instruments mentioned below which should aid considerably not only in diagnostic pathology but in investigative pathology as well.

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