scholarly journals Painlevé–Gullstrand form of the Lense–Thirring Spacetime

Universe ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 105
Author(s):  
Joshua Baines ◽  
Thomas Berry ◽  
Alex Simpson ◽  
Matt Visser
Keyword(s):  
The Body ◽  
Einstein Equations ◽  
Kerr Metric ◽  
Slow Rotation ◽  
Type I ◽  
Observational Astronomy ◽  
Kerr Spacetime ◽  
Schwarzschild Geometry ◽  
Distance Approximation ◽  
Curvature Tensors

The standard Lense–Thirring metric is a century-old slow-rotation large-distance approximation to the gravitational field outside a rotating massive body, depending only on the total mass and angular momentum of the source. Although it is not an exact solution to the vacuum Einstein equations, asymptotically the Lense–Thirring metric approaches the Kerr metric at large distances. Herein we shall discuss a specific variant of the standard Lense–Thirring metric, carefully chosen for simplicity, clarity, and various forms of improved mathematical and physical behaviour, (to be more carefully defined in the body of the article). We shall see that this Lense–Thirring variant can be viewed as arising from the linearization of a suitably chosen tetrad representing the Kerr spacetime. In particular, we shall construct an explicit unit-lapse Painlevé–Gullstrand variant of the Lense–Thirring spacetime, one that has flat spatial slices, a very simple and physically intuitive tetrad, and extremely simple curvature tensors. We shall verify that this variant of the Lense–Thirring spacetime is Petrov type I, (so it is not algebraically special), but nevertheless possesses some very straightforward timelike geodesics, (the “rain” geodesics). We shall also discuss on-axis and equatorial geodesics, ISCOs (innermost stable circular orbits) and circular photon orbits. Finally, we wrap up by discussing some astrophysically relevant estimates, and analyze what happens if we extrapolate down to small values of r; verifying that for sufficiently slow rotation we explicitly recover slowly rotating Schwarzschild geometry. This Lense–Thirring variant can be viewed, in its own right, as a “black hole mimic”, of direct interest to the observational astronomy community.

THYROID DYSFUNCTION IN PATIENTS WITH CHRONIC KIDNEY DISEASE: THE STATE OF THE PROBLEM AND THE WAYS OF SOLVING

2018 ◽  
Vol 22 (4) ◽  
pp. 40-49 ◽  
Author(s):  
A. R. Volkova ◽  
O. D. Dygun ◽  
B. G. Lukichev ◽  
S. V. Dora ◽  
O. V. Galkina
Keyword(s):  
Chronic Kidney Disease ◽  
Thyroid Gland ◽  
Kidney Disease ◽  
Thyroid Hormones ◽  
Thyroid Function ◽  
Thyroid Dysfunction ◽  
The Body ◽  
Type I ◽  
Low T3 ◽  
Iodine Excretion

Disturbance of the thyroid function is often detected in patients with different profiles. A special feature of patients with chronic kidney  disease is the higher incidence of various thyroid function  disturbances, especially hypothyroidism. It is known that in patients  with chronic kidney disease (CKD) iodine excretion from the body is  violated, since normally 90% of iodine is excreted in urine.  Accumulation of high concentrations of inorganic iodine leads to the  formation of the Wolf-Chaikoff effect: suppression of iodine  organization in the thyroid gland and disruption of the thyroid  hormones synthesis. Peripheral metabolism of thyroid hormones is  also disturbed, namely, deiodinase type I activity is suppressed and  peripheral conversion of T4 into T3 is inhibited (so-called low T3  syndrome). Therefore, patients with CKD are often diagnosed with  hypothyroidism, and the origin of hypothyroidism is not always  associated with the outcome of autoimmune thyroiditis. The article  presents an overview of a large number of population studies of  thyroid gland dysfunction in patients with CKD, as well as  experimental data specifying the pathogenetic mechanisms of  thyroid dysfunction in patients with CKD. Therapeutic tactics are still  not regulated. However, in a number of studies, replacement therapy with thyroid hormones in patients with CKD had some advantages.

The Kerr solution

2018 ◽  
Author(s):  
Nathalie Deruelle ◽  
Jean-Philippe Uzan
Keyword(s):  
Kerr Black Hole ◽  
Geodesic Equation ◽  
Einstein Equations ◽  
Kerr Metric ◽  
Kerr Solution ◽  
Axially Symmetric ◽  
Observable Universe ◽  
Einstein Vacuum Equations ◽  
Einstein Vacuum ◽  
The Many

This chapter covers the Kerr metric, which is an exact solution of the Einstein vacuum equations. The Kerr metric provides a good approximation of the spacetime near each of the many rotating black holes in the observable universe. This chapter shows that the Einstein equations are nonlinear. However, there exists a class of metrics which linearize them. It demonstrates the Kerr–Schild metrics, before arriving at the Kerr solution in the Kerr–Schild metrics. Since the Kerr solution is stationary and axially symmetric, this chapter shows that the geodesic equation possesses two first integrals. Finally, the chapter turns to the Kerr black hole, as well as its curvature singularity, horizons, static limit, and maximal extension.

scholarly journals Collagen-Based Electrospun Materials for Tissue Engineering: A Systematic Review

2021 ◽  
Vol 8 (3) ◽  
pp. 39
Author(s):  
Britani N. Blackstone ◽  
Summer C. Gallentine ◽  
Heather M. Powell
Keyword(s):  
Systematic Review ◽  
Tissue Engineering ◽  
Collagen Type I ◽  
The Body ◽  
Pool Data ◽  
Type I ◽  
High Concentrations ◽  
Increased Strength

Collagen is a key component of the extracellular matrix (ECM) in organs and tissues throughout the body and is used for many tissue engineering applications. Electrospinning of collagen can produce scaffolds in a wide variety of shapes, fiber diameters and porosities to match that of the native ECM. This systematic review aims to pool data from available manuscripts on electrospun collagen and tissue engineering to provide insight into the connection between source material, solvent, crosslinking method and functional outcomes. D-banding was most often observed in electrospun collagen formed using collagen type I isolated from calfskin, often isolated within the laboratory, with short solution solubilization times. All physical and chemical methods of crosslinking utilized imparted resistance to degradation and increased strength. Cytotoxicity was observed at high concentrations of crosslinking agents and when abbreviated rinsing protocols were utilized. Collagen and collagen-based scaffolds were capable of forming engineered tissues in vitro and in vivo with high similarity to the native structures.

Comprehensive Review on Neuro-Degenerative Type 3DM

2021 ◽  
Vol 18 ◽  
Author(s):  
Chandani V. Chandarana ◽  
Salona Roy
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Signaling ◽  
Insulin Signalling ◽  
Amyloid Β ◽  
Diabetes Mellitus Type 1 ◽  
Current Data ◽  
The Body ◽  
Type I ◽  
Therapeutic Benefits

: Alzheimer disease (AD) is thought to be the metabolic illness raised by defective insulin signaling, insulin resistance, and low insulin levels in the brain, according to a growing body of research. The "Type 3 diabetes" has been postulated for AD because reduced insulin signalling has molecular and physiological consequences that are comparable to Type I and Type 2 diabetes mellitus (Type 1 DM and Type 2 DM, respectively). The similarities between type 2 diabetes and Alzheimer's disease suggest that these clinical trials might yield therapeutic benefits. However, it's important to note that lowering your risk of Alzheimer's dementia, whether you have diabetes or not, is still a multidimensional process involving factors like exercise, smoking, alcohol, food, and mental challenge. The current aim is to show the relationship between T3D and AD being based on both the processing of amyloid-β (Aβ) precursor protein toxicity and the clearance of Aβ are the result of an impaired insulin signaling. The brain's metabolism with its high lipid content and energy needs, places excess demands on mitochondria and appears more susceptible to oxidative damage than the rest of the body. Current data suggests that increased oxidative stress relates to amyloid-β (Aβ) pathology and onset of AD.

scholarly journals Type I Interferon Inhibition and Dendritic Cell Activation during Gammaherpesvirus Respiratory Infection

2007 ◽  
Vol 81 (18) ◽  
pp. 9778-9789 ◽  
Author(s):  
Janet L. Weslow-Schmidt ◽  
Nancy A. Jewell ◽  
Sara E. Mertz ◽  
J. Pedro Simas ◽  
Joan E. Durbin ◽  
...  
Keyword(s):  
Dendritic Cells ◽  
Dendritic Cell ◽  
Cell Activation ◽  
Type I Interferon ◽  
Plasmacytoid Dendritic Cells ◽  
The Body ◽  
Type I ◽  
Type I Ifn ◽  
Dendritic Cell Activation ◽  
Murine Gammaherpesvirus

ABSTRACT The respiratory tract is a major mucosal site for microorganism entry into the body, and type I interferon (IFN) and dendritic cells constitute a first line of defense against viral infections. We have analyzed the interaction between a model DNA virus, plasmacytoid dendritic cells, and type I IFN during lung infection of mice. Our data show that murine gammaherpesvirus 68 (γHV68) inhibits type I IFN secretion by dendritic cells and that plasmacytoid dendritic cells are necessary for conventional dendritic cell maturation in response to γHV68. Following γHV68 intranasal inoculation, the local and systemic IFN-α/β response is below detectable levels, and plasmacytoid dendritic cells are activated and recruited into the lung with a tissue distribution that differs from that of conventional dendritic cells. Our results suggest that plasmacytoid dendritic cells and type I IFN have important but independent roles during the early response to a respiratory γHV68 infection. γHV68 infection inhibits type I IFN production by dendritic cells and is a poor inducer of IFN-α/β in vivo, which may serve as an immune evasion strategy.

scholarly journals Meniscal allograft transplantation in rabbit

2015 ◽  
Vol 87 (4) ◽  
pp. 2205-2216
Author(s):  
LIANA M. VILELA ◽  
RICARDO J. DEL CARLO ◽  
EDSON V. Melo FILHO ◽  
LUKIYA S.C. FAVARATO ◽  
TATIANA S. DUARTE ◽  
...  
Keyword(s):  
Collagen Type I ◽  
Collagen Fibers ◽  
The Body ◽  
Type I ◽  
Meniscal Allograft Transplantation ◽  
Allograft Transplantation ◽  
Meniscal Allograft ◽  
Preservation Method ◽  
Transplantation Technique ◽  
Partial Fixation

This study evaluated the technique for meniscal allograft transplantation using allografts preserved in glycerin 98% in rabbits. Euthanasia was performed at 70 days to compare the transplanted (TM1 to TM16) versus the contralateral meniscus (OM1 to OM16). Sixteen menisci, 8 transplanted and 8 contralateral, were submitted to gross examination, histomorphometric analysis for identification and quantification of cellular type, and for quantification and distribution of collagen fibers. A revascularization study was conducted in all of the other samples. Lengths of the OM varied from 0.9 to 1.0 cm and two TM were smaller. All TM were completely attached to the synovial membrane, except for one case that presented partial fixation. Both, TM and OM had similar amounts of chondrocytes, fibroblasts and fibrocytes, and at the horns, chondrocytes were predominant. The collagen fibers in TM were well organized throughout the body, and disorganized at the horns. These fibers in OM were organized. The amounts of collagen type I and III, and the vascularization of the perimeniscal tissue and of the edge were similar in OM and TM. These results demonstrated graft integration and thus this transplantation technique and preservation method may be recommended.

scholarly journals Occurrence of nematodes of the genus Anisakis in Mediterranean and Atlantic fish marketed in Sardinia

2017 ◽  
Vol 6 (1) ◽  
Author(s):  
Daniele Casti ◽  
Christian Scarano ◽  
Maria Cristina Piras ◽  
Paolo Merella ◽  
Sonia Muglia ◽  
...  
Keyword(s):  
Visual Inspection ◽  
Sensu Stricto ◽  
Body Cavity ◽  
The Body ◽  
Type I ◽  
Merluccius Merluccius ◽  
Commercial Fish ◽  
Scomber Colias ◽  
Third Stage ◽  
The Mean

Anisakiasis is a gastrointestinal fishborne zoonosis caused by the ingestion of third stage larvae of the genus <em>Anisakis</em>. Between January and December 2013, 1112 specimens of four commercial fish species (<em>Engraulis encrasicolus, Merluccius merluccius, Scomber colias</em> and <em>Trachurus mediterraneus</em>) marketed in Sardinia (Italy) were examined for <em>Anisakis</em> sp. The overall prevalence of <em>Anisakis</em> spp larvae was 39.9%, all morphologically identified as Type I. <em>Scomber colias</em> showed the highest prevalence (100%), followed by <em>M. merluccius</em> (Atlantic 91.0%, Mediterranean 71.2%), <em>T. mediterraneus</em> (32.7%) and <em>E. encrasicolus</em> (25.9%). All the larvae found in Mediterranean hosts were genetically identified as <em>Anisakis pegreffii</em>, whereas 90.0% of the larvae found in the Atlantic <em>M. merluccius</em> belonged to <em>Anisakis simplex sensu stricto</em> and 10.0% to <em>A. pegreffii</em>. The mean abundance of <em>Anisakis</em> sp. larvae was positively correlated with fish size in <em>E. encrasicolus</em>, Atlantic <em>M. merluccius</em> and local <em>M. merluccius</em>. The prevalence of infection was greater in the body cavity (37.9%) than in the edible muscle (9.4%). However, 1.8% of the examined fish were infected exclusively in the muscle. Therefore, the risk associated to the consumption of raw or undercooked fishery products poses the need of measures such as visual inspection and preventive treatments to guarantee consumers’ health.

scholarly journals Individual-typological features of regulation of cardiorhythm in foreign students during education process

2019 ◽  
Vol 3 (Issue 4) ◽  
pp. 199 ◽  
Author(s):  
Ainura M. Satarkulova ◽  
Shadiya Yu Aisaeva ◽  
Almaz S. Shanazarov
Keyword(s):  
Foreign Students ◽  
Parasympathetic Nervous System ◽  
Heart Rhythm ◽  
The Body ◽  
Type I ◽  
Central Regulation ◽  
Type Iii ◽  
Type Iv ◽  
Autonomous Regulation ◽  
Education Process

Objective: In studies of the mechanisms of human adaptation to professional and educational activities, as well as in clinical practice, the method of mathematical analysis of heart rate variability (HRV) is widely used. Based on this, the aim of this paper is to determine the typology and characteristics of the vegetative regulation of the heart as a prenosological control of the functional state of the body of practically healthy foreign students. Methods: In 2018, 389 male students from India and Pakistan, which are studying at the International higher school of medicine (ISM) aged 17-24, served as test subjects. For each student, the main HRV parameters were recorded in a sitting position for 5 minutes by means of “PSYCHOPHYSIOLOGIST” software and hardware company Medicom MTD  (Russia). Results: In total, 52% of young men had type I (with a moderate predominance of central regulation), 5% - type II (with a pronounced predominance of central regulation), 36% - type III (with a moderate predominance of autonomous regulation), and 7% - type IV (with a pronounced predominance of autonomous regulation). Students with a predominance of central regulation (types I and II) compared with types III and IV (predominance of autonomous regulation) have an excess of sympathetic influences on the heart, as indicated by reliably low values ​​of the SDNN, Mo, TP and high level of SI, which leads to various dysfunctional disorders, especially with severe centralization. In the group of persons with type III, a balance is maintained between the tone of the sympathetic and parasympathetic nervous system, while type IV shows a significant prevalence of parasympathetic effects on the heart rhythm. Conclusion: The results indicate a risk of developing disadaptation in the students' body during education process and the importance of systematic monitoring to detect early cardiac arrhythmias.

scholarly journals Exact Axially Symmetric Solution inf(T)Gravity Theory

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Gamal G. L. Nashed
Keyword(s):  
Vacuum Solution ◽  
Gravity Theory ◽  
Kerr Metric ◽  
Radial Coordinate ◽  
Lorentz Transformations ◽  
Axially Symmetric ◽  
Field Equations ◽  
Tetrad Field ◽  
Kerr Spacetime ◽  
Euler’S Angles

A general tetrad field with sixteen unknown functions is applied to the field equations off(T)gravity theory. An analytic vacuum solution is derived with two constants of integration and an angleΦthat depends on the angle coordinateϕand radial coordinater. The tetrad field of this solution is axially symmetric and the scalar torsion vanishes. We calculate the associated metric of the derived solution and show that it represents Kerr spacetime. Finally, we show that the derived solution can be described by two local Lorentz transformations in addition to a tetrad field that is the square root of the Kerr metric. One of these local Lorentz transformations is a special case of Euler’s angles and the other represents a boost when the rotation parameter vanishes.

THE EFFECTS OF ALTERED AQUATIC AND AERIAL RESPIRATORY GAS CONCENTRATIONS ON AIR-BREATHING PATTERNS IN A PRIMITIVE FISH (AMIA CALVA)

1993 ◽  
Vol 181 (1) ◽  
pp. 81-94 ◽  
Author(s):  
M. S. Hedrick ◽  
D. R. Jones
Keyword(s):  
Air Flow ◽  
The Body ◽  
Type I ◽  
Type Ii ◽  
Breathing Frequency ◽  
Breathing Patterns ◽  
Flow Measurements ◽  
Air Breathing ◽  
Gas Bladder ◽  
Amia Calva

The mechanisms and physiological control of air-breathing were investigated in an extant halecomorph fish, the bowfin (Amia calva). Air flow during aerial ventilation was recorded by pneumotachography in undisturbed Amia calva at 20–24°C while aquatic and aerial gas concentrations were independently varied. Separation of aquatic and aerial gases was used in an attempt to determine whether Amia calva monitor and respond to changes in the external medium per se or to changes in dissolved gases within the body. Air flow measurements revealed two different types of ventilatory patterns: type I air-breaths were characterized by exhalation followed by inhalation; type II air-breaths, which have not been described previously in Amia calva, consisted of single inhalations with no expiratory phase. Expired volume (Vexp) for type I breaths ranged from 11.6+/−1.1 to 26.7+/− 2.9 ml kg-1 (95 % confidence interval; N=6) under normoxic conditions and was unaffected by changes in aquatic or aerial gases. Gas bladder volume (VB), determined in vitro, was 80 ml kg-1; the percentage of gas exchanged for type I breaths ranged from 14 to 33 % of VB in normoxia. Fish exposed to aquatic and aerial normoxia (PO2=19-21 kPa), or aerial hypercapnia (PCO2=4.9 kPa) in normoxic water, used both breath types with equal frequency. Aquatic or aerial hypoxia (PO2=6-7 kPa) significantly increased air-breathing frequency in four of eight fish and the ventilatory pattern changed to predominantly type I air-breaths (75–92 % of total breaths). When fish were exposed to 100 % O2 in the aerial phase while aquatic normoxia or hypoxia was maintained, air-breathing frequency either increased or did not change. Compared with normoxic controls, however, type II breaths were used almost exclusively (more than 98 % of total breaths). Type I breaths appear to be under feedback control from O2-sensitive chemoreceptors since they were stimulated by aquatic or aerial hypoxia and were nearly abolished by aerial hyperoxia. These results also indicate that Amia calva respond to changes in intravascular PO2; however, externally facing chemoreceptors that stimulate air-breathing in aquatic hypoxia cannot be discounted. Type II air- breaths, which occurred in aerial hyperoxia, despite aquatic hypoxia, appear to be stimulated by reductions of VB, suggesting that type II breaths are controlled by volume-sensitive gas bladder stretch receptors. Type II breaths are likely to have a buoyancy-regulating function.

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