scholarly journals Measurable maximal energy and minimal time interval

2014 ◽  
Vol 92 (10) ◽  
pp. 1124-1129 ◽  
Author(s):  
Abdel Nasser Tawfik ◽  
Eiman Abou El Dahab

The possibility of finding the measurable maximal energy and the minimal time interval is discussed in different quantum aspects. It is found that the linear generalized uncertainty principle (GUP) approach gives a nonphysical result. Based on large scale Schwarzschild solution, the quadratic GUP approach is utilized. The calculations are performed at the shortest distance, at which the general relativity is assumed to be a good approximation for the quantum gravity and at larger distances, as well. It is found that both maximal energy and minimal time have the order of the Planck time. Then, the uncertainties in both quantities are accordingly bounded. Some physical insights are addressed. Also, the implications on the physics of early Universe and on quantized mass are outlined. The results are related to the existence of finite cosmological constant and minimum mass (mass quanta).

2020 ◽  
Vol 98 (8) ◽  
pp. 801-809
Author(s):  
S. Hamid Mehdipour

We present a general procedure for constructing exact black hole (BH) solutions with a magnetic charge in the context of nonlinear electrodynamics (NED) theory as well as in the coherent state approach to noncommutative geometry (NCG). In this framework, the Lagrangian density for a noncommutative Hayward BH is obtained and the weak energy condition is satisfied. The noncommutative Hayward solution depends on two kind of charges, without which the Schwarzschild solution is applicable. Moreover, to find a link between the BH evaporation and uncertainty relations, we may calculate the Hawking temperature and find the effect of the Lagrangian density of BHs on the Hawking radiation. Therefore, a generalized uncertainty principle (GUP) emerges from the modified Hawking temperature in Einstein–NED theory. The origin of this GUP is the combined influence of a nonlinear magnetic source and an intrinsic property of the manifold associated with a fictitious charge. Finally, we find that there is an upper bound on the Lagrangian uncertainty of the BHs that is caused by the NED field and (or) the fictitious charge.


2008 ◽  
Vol 23 (3) ◽  
pp. 294-303 ◽  
Author(s):  
Katia Ferreira Güenaga ◽  
Suzana Angélica Silva Lustosa ◽  
Sarhan Sydney Saad ◽  
Humberto Saconato ◽  
Delcio Matos

PURPOSE: The controversy regarding whether loop ileostomy or loop transverse colostomy is a better method for temporary decompression of colorectal anastomosis motivated this review. METHODS: Five randomized trials were included, with 334 patients: 168 in the loop ileostomy group and 166 in the loop transverse colostomy group. The outcomes analyzed were: 1. Mortality; 2. Wound infection; 3. Time of stoma formation; 4. Time of stoma closure; 5. Time interval between stoma formation and closure; 6. Stoma prolapse; 7. Stoma retraction; 8. Parastomal hernia; 9. Parastomal fistula; 10. Stenosis; 11. Necrosis; 12. Skin irritation; 13. Ileus; 14. Bowel leakage; 15. Reoperation; 16. Patient adaptation; 17. Length of hospital stay; 18. Colorectal anastomotic dehiscence; 19. Incisional hernia; 20. Postoperative bowel obstruction. RESULTS: Stoma prolapse was statistically significant (p = 0.00001), but with statistical heterogeneity; the sensitive analysis was applied, excluding the trials that included emergency surgery, and this showed: p = 0.02, with I² = 0% for the heterogeneity test. CONCLUSIONS: The outcomes reported were not statistically or clinically significant except for stoma prolapse. Better evidence for making the choice between loop ileostomy or loop colostomy requires large-scale randomized controlled trials.


2016 ◽  
Vol 25 (03) ◽  
pp. 1630007 ◽  
Author(s):  
Thomas Buchert ◽  
Alan A. Coley ◽  
Hagen Kleinert ◽  
Boudewijn F. Roukema ◽  
David L. Wiltshire

In this paper, we summarize some of the main observational challenges for the standard Friedmann–Lemaître–Robertson–Walker (FLRW) cosmological model and describe how results recently presented in the parallel session “Large-scale Structure and Statistics” (DE3) at the “Fourteenth Marcel Grossman Meeting on General Relativity” are related to these challenges.


2010 ◽  
Vol 19 (14) ◽  
pp. 2345-2351 ◽  
Author(s):  
AHARON DAVIDSON ◽  
ILYA GURWICH

Hawking–Bekenstein entropy formula seems to tell us that no quantum degrees of freedom can reside in the interior of a black hole. We suggest that this is a consequence of the fact that the volume of any interior sphere of finite surface area simply vanishes. Obviously, this is not the case in general relativity. However, we show that such a phenomenon does occur in various gravitational theories which admit a spontaneously induced general relativity. In such theories, due to a phase transition (one-parameter family degenerates) which takes place precisely at the would-have-been horizon, the recovered exterior Schwarzschild solution connects, by means of a self-similar transition profile, with a novel "hollow" interior exhibiting a vanishing spatial volume and a locally varying Newton constant. This constitutes the so-called "hollowgraphy" driven holography.


Author(s):  
Nurcin Celik ◽  
Esfandyar Mazhari ◽  
John Canby ◽  
Omid Kazemi ◽  
Parag Sarfare ◽  
...  

Simulating large-scale systems usually entails exhaustive computational powers and lengthy execution times. The goal of this research is to reduce execution time of large-scale simulations without sacrificing their accuracy by partitioning a monolithic model into multiple pieces automatically and executing them in a distributed computing environment. While this partitioning allows us to distribute required computational power to multiple computers, it creates a new challenge of synchronizing the partitioned models. In this article, a partitioning methodology based on a modified Prim’s algorithm is proposed to minimize the overall simulation execution time considering 1) internal computation in each of the partitioned models and 2) time synchronization between them. In addition, the authors seek to find the most advantageous number of partitioned models from the monolithic model by evaluating the tradeoff between reduced computations vs. increased time synchronization requirements. In this article, epoch- based synchronization is employed to synchronize logical times of the partitioned simulations, where an appropriate time interval is determined based on the off-line simulation analyses. A computational grid framework is employed for execution of the simulations partitioned by the proposed methodology. The experimental results reveal that the proposed approach reduces simulation execution time significantly while maintaining the accuracy as compared with the monolithic simulation execution approach.


2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Surajit Kalita ◽  
Banibrata Mukhopadhyay

Abstract A number of recent observations have suggested that the Einstein’s theory of general relativity may not be the ultimate theory of gravity. The f(R) gravity model with R being the scalar curvature turns out to be one of the best bet to surpass the general relativity which explains a number of phenomena where Einstein’s theory of gravity fails. In the f(R) gravity, behaviour of the spacetime is modified as compared to that of given by the Einstein’s theory of general relativity. This theory has already been explored for understanding various compact objects such as neutron stars, white dwarfs etc. and also describing evolution of the universe. Although researchers have already found the vacuum spacetime solutions for the f(R) gravity, yet there is a caveat that the metric does have some diverging terms and hence these solutions are not asymptotically flat. We show that it is possible to have asymptotically flat spherically symmetric vacuum solution for the f(R) gravity, which is different from the Schwarzschild solution. We use this solution for explaining various bound orbits around the black hole and eventually, as an immediate application, in the spherical accretion flow around it.


2018 ◽  
Vol 12 (4) ◽  
pp. 1401-1414 ◽  
Author(s):  
Marie G. P. Cavitte ◽  
Frédéric Parrenin ◽  
Catherine Ritz ◽  
Duncan A. Young ◽  
Brice Van Liefferinge ◽  
...  

Abstract. We reconstruct the pattern of surface accumulation in the region around Dome C, East Antarctica, since the last glacial. We use a set of 18 isochrones spanning all observable depths of the ice column, interpreted from various ice-penetrating radar surveys and a 1-D ice flow model to invert for accumulation rates in the region. The shallowest four isochrones are then used to calculate paleoaccumulation rates between isochrone pairs using a 1-D assumption where horizontal advection is negligible in the time interval of each layer. We observe that the large-scale (100s km) surface accumulation gradient is spatially stable through the last 73 kyr, which reflects current modeled and observed precipitation gradients in the region. We also observe small-scale (10 s km) accumulation variations linked to snow redistribution at the surface, due to changes in its slope and curvature in the prevailing wind direction that remain spatially stationary since the last glacial.


2020 ◽  
Vol 3 (Supplement_1) ◽  
pp. 28-30
Author(s):  
A Kundra ◽  
T Ritchie ◽  
M Ropeleski

Abstract Background Fecal Calprotectin (FC) is helpful in distinguishing functional from organic bowel disease. Also, it has proven useful in monitoring disease activity in inflammatory bowel disease (IBD). The uptake of its use in clinical practice has increased considerably, though access varies significantly. Studies exploring current practice patterns among GI specialists and how to optimize its use are limited. In 2017, Kingston Health Sciences Centre (KHSC) began funding FC testing at no cost to patients. Aims We aimed to better understand practice patterns of gastroenterologists in IBD patients where there is in house access to FC assays, and to generate hypotheses regarding its optimal use in IBD monitoring. We hypothesize that FC is not being used in a regular manner for monitoring of IBD patients. Methods A retrospective chart audit study was done on all KHSC patients who had FC testing completed from 2017–2018. Qualitative data was gathered from dictated reports using rigorous set definitions regarding indication for the test, change in clinical decision making, and frequency patterns of testing. Specifically, change in use for colonoscopy or in medical therapy was coded only if the dictated note was clear that a decision hinged largely on the FC result. Frequency of testing was based on test order date. Reactive testing was coded as tests ordered to confirm a clinical flare. Variable testing was coded where monitoring tests that varied in intervals greater than 3 months and crossed over the other set frequency codes. Quantitative data regarding FC test values, and dates were also collected. This data was then analyzed using descriptive statistics. Results Of the 834 patients in our study, 7 were under 18 years old and excluded. 562(67.34%) of these patients had a pre-existing diagnosis of IBD; 193 (34%) with Ulcerative Colitis (UC), 369 (66%) with Crohn’s Disease (CD). FC testing changed the clinician’s decision for medical therapy in 12.82% of cases and use for colonoscopy 13.06% of the time for all comers. Of the FC tests, 79.8% were sent in a variable frequency pattern and 2.68% with reactive intent. The remaining 17.5% were monitored with a regular pattern, with 8.57% patients having their FC monitored at regular intervals greater than 6 months, 7.68% every 6 months, and 1.25% less than 6 months. The average FC level of patients with UC was 356.2ug/ml and 330.6 ug/ml for CD. The mean time interval from 1st to 2nd test was 189.6 days. Conclusions FC testing changed clinical decisions regarding medical therapy and use for colonoscopy about 13% of the time. FC testing was done variably 79.8% of the time, where as 17.5% of patients had a regular FC monitoring schedule. An optimal monitoring interval for IBD flares using FC for maximal clinical benefit has yet to be determined. Large scale studies will be required to answer this question. Funding Agencies None


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