scholarly journals A complete study of conformally flat pseudo-symmetric spacetimes in the theory of F(R)-gravity

2022 ◽  
Vol 32 ◽  
pp. 105053
Author(s):  
Avik De ◽  
Simran Arora ◽  
Uday Chand De ◽  
P.K. Sahoo
Keyword(s):  
Conformally Flat ◽  
Symmetric Spacetimes ◽  
Complete Study

On Conformally Flat Almost Pseudo-Ricci Symmetric Spacetimes

2012 ◽  
Vol 51 (9) ◽  
pp. 2878-2887 ◽  
Author(s):  
Avik De ◽  
Cihan Özgür ◽  
Uday Chand De
Keyword(s):  
Conformally Flat ◽  
Symmetric Spacetimes

scholarly journals A Relativistic Algorithm with Isotropic Coordinates

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
S. A. Ngubelanga ◽  
S. D. Maharaj
Keyword(s):  
Spherically Symmetric ◽  
Conformally Flat ◽  
Einstein Field Equations ◽  
Elementary Functions ◽  
Field Equations ◽  
Isotropic Coordinates ◽  
New Exact Solutions ◽  
Symmetric Spacetimes ◽  
Particular Solution ◽  
Conformally Flat Metric

We study spherically symmetric spacetimes for matter distributions with isotropic pressures. We generate new exact solutions to the Einstein field equations which also contain isotropic pressures. We develop an algorithm that produces a new solution if a particular solution is known. The algorithm leads to a nonlinear Bernoulli equation which can be integrated in terms of arbitrary functions. We use a conformally flat metric to show that the integrals may be expressed in terms of elementary functions. It is important to note that we utilise isotropic coordinates unlike other treatments.

Dust static plane symmetric solutions and their conformal vector fields in f(R) theory of gravity

2018 ◽  
Vol 33 (37) ◽  
pp. 1850222 ◽  
Author(s):  
Ghulam Shabbir ◽  
Fiaz Hussain ◽  
F. M. Mahomed ◽  
Muhammad Ramzan
Keyword(s):  
Vector Fields ◽  
Killing Vector ◽  
Conformally Flat ◽  
Killing Vector Fields ◽  
Plane Symmetric ◽  
Symmetric Spacetimes ◽  
Conformal Vector ◽  
Conformal Vector Fields ◽  
Theory Of Gravity ◽  
Static Plane

We first find the dust solutions of static plane symmetric spacetimes in the theory of f(R) gravity. Then using the direct integration technique on the solutions obtained, we deduce the conformal vector fields. This is performed in the context of f(R) theory of gravity. There exist six cases. Out of these, in five cases the spacetimes become conformally flat and admit 15 conformal vector fields, whereas in the sixth case, conformal vector fields become Killing vector fields.

The Social Origins and Provenance of the English Bishops during the Reign of Edward II

1959 ◽  
Vol 9 ◽  
pp. 51-79
Author(s):  
K. Edwards
Keyword(s):  
Middle Ages ◽  
Social Background ◽  
Early Career ◽  
The Political ◽  
Social Origins ◽  
Political Activities ◽  
Edward Ii ◽  
The Social ◽  
Complete Study ◽  
History Of

During the last twenty or twenty-five years medieval historians have been much interested in the composition of the English episcopate. A number of studies of it have been published on periods ranging from the eleventh to the fifteenth and early sixteenth centuries. A further paper might well seem superfluous. My reason for offering one is that most previous writers have concentrated on analysing the professional circles from which the bishops were drawn, and suggesting the influences which their early careers as royal clerks, university masters and students, secular or regular clergy, may have had on their later work as bishops. They have shown comparatively little interest in their social background and provenance, except for those bishops who belonged to magnate families. Some years ago, when working on the political activities of Edward II's bishops, it seemed to me that social origins, family connexions and provenance might in a number of cases have had at least as much influence on a bishop's attitude to politics as his early career. I there fore collected information about the origins and provenance of these bishops. I now think that a rather more careful and complete study of this subject might throw further light not only on the political history of the reign, but on other problems connected with the character and work of the English episcopate. There is a general impression that in England in the later middle ages the bishops' ties with their dioceses were becoming less close, and that they were normally spending less time in diocesan work than their predecessors in the thirteenth century.

Cluster analysis for large data sets: applications to individual aerosol particles from the mid-pacific

1992 ◽  
Vol 50 (2) ◽  
pp. 1488-1489
Author(s):  
Thomas W. Shattuck ◽  
James R. Anderson ◽  
Neil W. Tindale ◽  
Peter R. Buseck
Keyword(s):  
Cluster Analysis ◽  
Chemical Reactivity ◽  
Large Data ◽  
Large Data Sets ◽  
Particle Analysis ◽  
Data Sets ◽  
Halogen Chemistry ◽  
Complete Study ◽  
Components Analysis ◽  
Automated Scanning

Individual particle analysis involves the study of tens of thousands of particles using automated scanning electron microscopy and elemental analysis by energy-dispersive, x-ray emission spectroscopy (EDS). EDS produces large data sets that must be analyzed using multi-variate statistical techniques. A complete study uses cluster analysis, discriminant analysis, and factor or principal components analysis (PCA). The three techniques are used in the study of particles sampled during the FeLine cruise to the mid-Pacific ocean in the summer of 1990. The mid-Pacific aerosol provides information on long range particle transport, iron deposition, sea salt ageing, and halogen chemistry.Aerosol particle data sets suffer from a number of difficulties for pattern recognition using cluster analysis. There is a great disparity in the number of observations per cluster and the range of the variables in each cluster. The variables are not normally distributed, they are subject to considerable experimental error, and many values are zero, because of finite detection limits. Many of the clusters show considerable overlap, because of natural variability, agglomeration, and chemical reactivity.

A novel predictive method for filler coflocculation with cellulose microfibrils

TAPPI Journal ◽  
2019 ◽  
Vol 18 (11) ◽  
pp. 653-664
Author(s):  
IGNACIO DE SAN PIO ◽  
KLAS G. JOHANSSON ◽  
PAUL KROCHAK
Keyword(s):  
Negative Impact ◽  
High Strength ◽  
Strength Properties ◽  
Cellulose Microfibrils ◽  
Paper Strength ◽  
Flow Loop ◽  
Cationic Starch ◽  
Reflectance Measurement ◽  
Drainage Rate ◽  
Complete Study

Different strategies aimed at reducing the negative impact of fillers on paper strength have been the objective of many studies during the past few decades. Some new strategies have even been patented or commercialized, yet a complete study on the behavior of the filler flocs and their effect on retention, drainage, and formation has not been found in literature. This type of research on fillers is often limited by difficulties in simulating high levels of shear at laboratory scale similar to those at mill scale. To address this challenge, a combination of techniques was used to compare preflocculation (i.e., filler is flocculated before addition to the pulp) with coflocculation strategies (i.e., filler is mixed with a binder and flocculated before addition to the pulp). The effect on filler and fiber flocs size was studied in a pilot flow loop using focal beam reflectance measurement (FBRM) and image analysis. Flocs obtained with cationic polyacrylamide (CPAM) and bentonite were shown to have similar shear resistance with both strategies, whereas cationic starch (CS) was clearly more advantageous when coflocculation strategy was used. The effect of flocculation strategy on drainage rate, STFI formation, ash retention, and standard strength properties was measured. Coflocculation of filler with CPAM plus bentonite or CS showed promising results and produced sheets with high strength but had a negative impact on wire dewatering, opening a door for further optimization.

Wegvoeringen en weggevoerden tijdens de meidagen van 1940

2014 ◽  
Vol 73 (3) ◽  
pp. 250-259
Author(s):  
Etienne Verhoeyen
Keyword(s):  
Decision Making ◽  
Large Majority ◽  
The Political ◽  
Extreme Right ◽  
Political Decision ◽  
Belgian Society ◽  
Complete Study ◽  
History Of ◽  
Risky Business ◽  
Political Decision Making

Met dit boek levert Frank Seberechts een nagenoeg volledige studie af van een van de minder fraai kanten van de Belgische samenleving in 1940: de administratieve arrestatie en de wegvoering naar Frankrijk van enkele duizenden personen (de ‘verdachten’), Belgen of in België verblijvende vreemdelingen. De extreem-rechtse en pro-Duitse arrestanten hebben na hun vrijlating dit feit politiek in hun voordeel uitgebaat, waardoor volledig in de schaduw kwam te staan dat de overgrote meerderheid van de weggevoerden joodse mensen waren die in de jaren voor de oorlog naar België waren gevlucht. Dat het beeld van de wegvoeringen niet volledig is, is grotendeels te wijten aan het feit dat de meeste archieven die hierop betrekking hebben tijdens de meidagen van 1940 vernietigd werden. Met name de politieke besluitvorming over de wegvoeringen vertoont nog steeds schemerzones, zodat het vastleggen van verantwoordelijkheden ook vandaag nog een gewaagde onderneming is.________Deportations and the deported during the Maydays in 1940 By means of this book Frank Seberechts provides an almost complete study of one of the less admirable sides of Belgian society in 1940: the administrative arrest and the deportation to France of some thousands of people (‘the suspects’), Belgians or foreigners residing in Belgium. The extreme-right and pro-German detainees politically exploited this fact after they had been freed, but this completely overshadowed the point that the large majority of the deported people were Jews who had fled to Belgium during the years preceding the war. This incomplete portrayal of the deportations is mainly due to the fact that most of the archives relating to the events had been destroyed during the Maydays of 1940. The history of the political decision-making about the deportations in particular still shows many grey areas and it is therefore still a risky business even today to determine which people should be held accountable.

scholarly journals Study for the Design of a Protocol to Assess the Impact of Stress in the Quality of Life of Workers

2021 ◽  
Vol 18 (4) ◽  
pp. 1413
Author(s):  
Patricia Concheiro-Moscoso ◽  
Betania Groba ◽  
Francisco José Martínez-Martínez ◽  
María del Carmen Miranda-Duro ◽  
Laura Nieto-Riveiro ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Occupational Stress ◽  
Categorical Variables ◽  
Complete Study ◽  
Stress Coping Strategies ◽  
Personal Level ◽  
Stress Influences ◽  
The Impact ◽  
Positive Effect

(1) Background: Work stress is one of the most relevant issues in public health. It has a significant impact on health, especially the development of mental disorders, causing occupational imbalance. There is a growing interest in the development of tools with a positive effect on workers. To this end, wearable technology is becoming increasingly popular, as it measures biometric variables like heartbeat, activity, and sleep. This information may be used to assess the stress a person is suffering, which could allow the development of stress coping strategies, both at a professional and personal level. (2) Methods: This paper describes an observational, analytical, and longitudinal study which will be set at a research center in A Coruña, Spain. Various scales and questionnaires will be filled in by the participants throughout the study. For the statistical analysis, specific methods will be used to evaluate the association between numerical and categorical variables. (3) Discussion: This study will lay the foundation for a bigger, more complete study to assess occupational stress in different work environments. This will allow us to begin to understand how occupational stress influences daily life activity and occupational balance, which could directly enhance the quality of life of workers if the necessary measures are taken.

scholarly journals Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 838
Author(s):  
David Hermann Lamparelli ◽  
Magdalena Maria Kleybolte ◽  
Malte Winnacker ◽  
Carmine Capacchione
Keyword(s):  
Anionic Polymerization ◽  
Sodium Hydride ◽  
Reactivity Ratios ◽  
Molecular Weights ◽  
Styrene Copolymers ◽  
Wide Range ◽  
Elastomeric Materials ◽  
Complete Study ◽  
Anionic Copolymerization ◽  
Trialkylaluminum Derivatives

Soluble heterocomplexes consisting of sodium hydride in combination with trialkylaluminum derivatives have been used as anionic initiating systems at 100 °C in toluene for convenient homo-, co- and ter-polymerization of myrcene with styrene and isoprene. In this way it has been possible to obtain elastomeric materials in a wide range of compositions with interesting thermal profiles and different polymeric architectures by simply modulating the alimentation feed and the (monomers)/(initiator systems) ratio. Especially, a complete study of the myrcene-styrene copolymers (PMS) was carried out, highlighting their tapered microstructures with high molecular weights (up to 159.8 KDa) and a single glass transition temperature. For PMS copolymer reactivity ratios, rmyr = 0.12 ± 0.003 and rsty = 3.18 ± 0.65 and rmyr = 0.10 ± 0.004 and rsty = 3.32 ± 0.68 were determined according to the Kelen–Tudos (KT) and extended Kelen–Tudos (exKT) methods, respectively. Finally, this study showed an easy accessible approach for the production of various elastomers by anionic copolymerization of renewable terpenes, such as myrcene, with commodities.

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