Causality violation in spatially closed space-times

1983 ◽  
Vol 15 (2) ◽  
pp. 165-172 ◽  
Author(s):  
Gregory J. Galloway
Keyword(s):  
Closed Space ◽  
Causality Violation

scholarly journals Use of masks in public places in Poland during SARS-Cov-2 epidemic: a covert observational study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Maria Ganczak ◽  
Oskar Pasek ◽  
Łukasz Duda – Duma ◽  
Dawid Świstara ◽  
Marcin Korzeń
Keyword(s):  
Health Promotion ◽  
Observational Study ◽  
Control Measure ◽  
Communication Channels ◽  
Public Spaces ◽  
Personal Health ◽  
Closed Space ◽  
Public Places ◽  
Health Control ◽  
Over Time

Abstract Background Face masks have been employed in the COVID-19 pandemic plans as a public and personal health control measure against the spread of SARS-CoV-2. In Poland, obligatory wearing of masks in public spaces was introduced on April 10th, 2020; a relaxation of previous universal measures was announced on May 29th, 2020, limiting use to indoor public places. Objective To assess use of masks or other protective devices in public spaces in Poland during the SARS-Cov-2 epidemic. Methods A non-participatory covert observational study was conducted on three dates, (10.05/18.05/25.05.2020) at public spaces in 13 regions with different risks. Ten consecutive individuals were observed by each of 82 medical students (n = 2460 observations), using a structured checklist. Results Among 2353 observed persons, the female/male ratios were 1.0, 1.1, and 1.0 on the three dates. Almost three quarters - 73.6% (n = 552/750) were using masks on date 1, 66.5% (544/818) on date 2; and 65.7% (516/785) on date 3. Cloth masks predominated on all dates (64.7–62.3%-62.6%), followed by medical (23.4–28.5%-26.9%). Being female (OR = 1.77–1.47-1.53 respectively) and location in a closed space (OR = 2.60–2.59-2.32) were each associated with higher usage. Participants in sports were about two times less likely to use masks (OR = 0.64–0.53-0.53) as compared to other activities. The proportion using masks correctly decreased gradually over time (364/552; 65.9%; 339/544; 62.3% and 304/516; 58.9%). More females wore masks correctly (date 1: 205/294; 69.7% vs 159/258; 61.6%, and date 3: 186/284; 65.5% vs 118/232; 50.9%; p = 0.045; p = 0.0008 respectively). Uncovered noses (47.3–52.7%) and masks around the neck (39.2–42.6%) were the most frequent incorrect practices. Conclusions Practices were not in line with official recommendations, especially among males, and deteriorated over time. Cloth masks were predominantly used in public spaces. Health promotion, through utilizing all available communication channels, would be helpful to increase compliance.

scholarly journals CELL RESPIRATION STUDIES

1927 ◽  
Vol 46 (1) ◽  
pp. 43-51
Author(s):  
Blake C. Wilbur ◽  
Geneva A. Daland ◽  
John Cohen
Keyword(s):  
Oxygen Consumption ◽  
Whole Blood ◽  
Repeated Measurements ◽  
Closed Space ◽  
Cell Respiration ◽  
Chemical Substances ◽  
Normal Individuals ◽  
Tissue Cells

A description is given of a closed space respiration apparatus which can be used to determine the amount of gas used or liberated by living blood or tissue cells, or chemical substances. Continuous observations can be made and repeated measurements recorded without interrupting the vital processes or destroying the cells. Studies of the oxygen consumption by whole blood in normal individuals and in patients with leucocytosis and myelogenous leucemia, as well as by white cells suspended in plasma, will be reported in subsequent papers.

MANIFOLD-SPLITTING REGULARIZATION, SELF-LINKING, TWISTING, WRITHING NUMBERS OF SPACE-TIME RIBBONS and POLYAKOV’S PROOF OF FERMI-BOSE TRANSMUTATIONS

1988 ◽  
Vol 03 (08) ◽  
pp. 1959-1979 ◽  
Author(s):  
CHIA-HSIUNG TZE
Keyword(s):  
Integral Formula ◽  
Space Time ◽  
Gauge Fields ◽  
Alternative Formulation ◽  
Complex Numbers ◽  
Closed Space ◽  
Feynman Path ◽  
Higher Dimensional ◽  
Linking Coefficient ◽  
In Memoriam

We present an alternative formulation of Polyakov’s regularization of Gauss’ integral formula for a single closed Feynman path. A key element in his proof of the D=3 fermi-bose transmutations induced by topological gauge fields, this regularization is linked here with the existence and properties of a nontrivial topological invariant for a closed space ribbon. This self-linking coefficient, an integer, is the sum of two differential characteristics of the ribbon, its twisting and writhing numbers. These invariants form the basis for a physical interpretation of our regularization. Their connection to Polyakov’s spinorization is discussed. We further generalize our construction to the self-linking, twisting and writhing of higher dimensional d=n (odd) submanifolds in D=(2n+1) space-time. Our comprehensive analysis intends to supplement Polyakov’s work as it identifies a natural path to its higher dimensional mathematical and physical generalizations. Combining the theorems of White on self-linking of manifolds and of Adams on nontrivial Hopf fibre bundles and the four composition-division algebras, we argue that besides Polyakov’s case where (d, D)=(1, 3) tied to complex numbers, the potentially interesting extensions are two chiral models with (d, D)=(3, 7) and (7, 15) uniquely linked to quaternions and octonions. In Memoriam Richard P. Feynman

scholarly journals KINKS, ENERGY CONDITIONS AND CLOSED TIMELIKE CURVES

2000 ◽  
Vol 09 (05) ◽  
pp. 531-541 ◽  
Author(s):  
PEDRO F. GONZÁLEZ-DÍAZ
Keyword(s):  
Energy Condition ◽  
Weak Energy Condition ◽  
Energy Conditions ◽  
Closed Timelike Curves ◽  
Causality Violation ◽  
Incoherent Radiation ◽  
Cylindrically Symmetric ◽  
Cylindrically Symmetric Spacetime ◽  
Geodesically Complete ◽  
Symmetric Spacetime

A link between the possibility of extending a geodesically incomplete kinked spacetime to a spacetime which is geodesically complete and the energy conditions is discussed for the case of a cylindrically-symmetric spacetime kink. It is concluded that neither the strong nor the weak energy condition can be satisfied in the four-dimensional example, though the latter condition may survive on the transversal sections of such a spacetime. It is also shown that the matter which propagates quantum-mechanically in a kinked spacetime can always be trapped by closed timelike curves, but signaling connections between that matter and any possible observer can only be made of totally incoherent radiation, so preventing observation of causality violation.

The restoration of a closed space with fixed bridgework

1965 ◽  
Vol 10 (1) ◽  
pp. 41-44
Author(s):  
George Wing ◽  
K. Godfrey
Keyword(s):  
Closed Space
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