Thermodynamics and the naked singularity in the Gamma-metric

We investigate a possible way of establishing a parallel between the third law of black hole mechanics, and the strong version of the third law of thermodynamics. We calculate the surface gravity and area for a naked singular null surface in the Gamma-metric and explain in what sense this behaviour violates thermodynamics

Statistical thermodynamics for a non-commutative special relativity: Emergence of a generalized quantum dynamics

There ought to exist a description of quantum field theory which does not depend on an external classical time. To achieve this goal, in a recent paper we have proposed a non-commutative special relativity in which space-time and matter degrees of freedom are treated as classical matrices with arbitrary commutation relations, and a space-time line element is defined using a trace. In the present paper, following the theory of Trace Dynamics, we construct a statistical thermodynamics for the non-commutative special relativity, and show that one arrives at a generalized quantum dynamics in which space and time are non-classical and have an operator status. In a future work, we will show how standard quantum theory on a classical space-time background is recovered from here.Comment: 21 pages. arXiv admin note: text overlap with arXiv:1106.091

Thermodynamics and the naked singularity in the Gamma-metric

We investigate a possible way of establishing a parallel between the third law of black hole mechanics, and the strong version of the third law of thermodynamics. We calculate the surface gravity and area for a naked singular null surface in the Gamma-metric and explain in what sense this behaviour violates thermodynamics

Bouncing and collapsing universes dual to late-time cosmological models

Scalar-tensor theories of gravity provide mathematically equivalent descriptions of Einstein's gravity with a scalar field, in a conformally connected spacetime, described in terms of the Jordan frame and the Einstein frame. In this paper, we use the Jordan frame-Einstein frame correspondence to explore dual universes with contrasting cosmological evolutions. We study the mapping between Einstein and Jordan frames where the Einstein frame universe describes the late-time evolution of the physical universe, which is driven by dark energy and non-relativistic matter. The Brans-Dicke theory of gravity is considered to be the dual scalar-tensor theory in the Jordan frame. We show that an Einstein frame universe, with cosmological evolution of the $\Lambda$CDM model, always corresponds to a bouncing Jordan frame universe governed by a Brans-Dicke theory. On the other hand, quintessence models of dark energy with non-relativistic matter component are shown to be always dual to a Brans-Dicke Jordan frame with a turn-around, that is, a bounce or a collapse. The evolution of the equation of state of the quintessence field determines whether the turn-around is a bounce or a collapse. The point of the Jordan frame turn-around for all the cases can be tuned anywhere by choosing an appropriate Brans-Dicke parameter. This essentially leads to an alternative description of the late-time evolution of the physical universe, in terms of a bouncing or collapsing Brans-Dicke universe in the Jordan frame. We further study the stability of such conformal maps against linear perturbations. An effective bouncing description of the current accelerating universe has interesting implications, for example, one may study the late-time cosmological perturbations as fluctuations in a bouncing scenario.Comment: 29 pages, 11 figures, major change

Detecting Acceleration-Enhanced Vacuum Fluctuations with Atoms Inside a Cavity

Some of the most prominent theoretical predictions of modern times, e.g., the Unruh effect, Hawking radiation, and gravity-assisted particle creation, are supported by the fact that various quantum constructs like particle content and vacuum fluctuations of a quantum field are observer-dependent. Despite being fundamental in nature, these predictions have not yet been experimentally verified because one needs extremely strong gravity (or acceleration) to bring them within the existing experimental resolution. In this Letter, we demonstrate that a post-Newtonian rotating atom inside a far-detuned cavity experiences strongly modified quantum fluctuations in the inertial vacuum. As a result, the emission rate of an excited atom gets enhanced significantly along with a shift in the emission spectrum due to the change in the quantum correlation under rotation. We propose an optomechanical setup that is capable of realizing such acceleration-induced particle creation with current technology. This provides a novel and potentially feasible experimental proposal for the direct detection of noninertial quantum field theoretic effects.Comment: Published in PR

Family History of Cancer and Tobacco Exposure in Index Cases of Pancreatic Ductal Adenocarcinoma

Aim. To examine interaction between history of cancer in first-degree relatives and tobacco smoking in index patients of pancreatic adenocarcinoma. Methods. We carried out a case-control involving 113 patients with pancreatic adenocarcinoma and 110 controls over a 12-month period at the Freeman Hospital, Newcastle upon Tyne, UK. They were all administered a detailed tobacco exposure questionnaire and a family history questionnaire. We calculated cumulative tobacco exposure and risk for pancreas cancer. Results. Both smokers (OR 3.01 (95% CI: 1.73 to 5.24)) and those with a family history of malignancy (OR 1.98 (95% CI: 1.15–3.38)) were more likely to develop pancreatic cancer. Having more than one first-degree relative with cancer did not significantly further increase the risk of pancreatic cancer. Amongst pancreatic cancer cases, cumulative tobacco exposure was significantly decreased (P = .032) in the group of smokers (current and ex-smokers) who had a family history of malignancy [mean (SD): 30.00 (24.77) pack-years versus 44.69 (28.47) pack-years with no such history]. Conclusions. Individuals with a family history of malignancy are at an increased risk of pancreatic cancer. Furthermore, individuals with a family history of malignancy and who smoke appear to require a lesser degree of tobacco exposure for the development of pancreatic cancer

Statistical analysis of entropy correction from topological defects in Loop Black Holes

In this paper we discuss the entropy of quantum black holes in the LQG formalism when the number of punctures on the horizon is treated as a quantum hair, that is we compute the black hole entropy in the grand canonical (area) ensemble. The entropy is a function of both the average area and the average number of punctures and bears little resemblance to the Bekenstein-Hawking entropy. In the thermodynamic limit, both the "temperature" and the chemical potential can be shown to be functions only of the average area per puncture. At a fixed temperature, the average number of punctures becomes proportional to the average area and we recover the Bekenstein-Hawking area-entropy law to leading order provided that the Barbero-Immirzi parameter, $\gamma$, is appropriately fixed. This also relates the chemical potential to $\gamma$. We obtain a sub-leading correction, which differs in signature from that obtained in the microcanonical and canonical ensembles in its sign but agrees with earlier results in the grand canonical ensemble.Comment: 12 pages, no figures. Version to appear in Phys. Rev.

The Role of Tobacco-Derived Carcinogens in Pancreas Cancer

The extremely poor outcome from pancreas cancer is well known. However, its aetiology less well appreciated, and the molecular mechanisms underlying this are poorly understood. Tobacco usage is one of the strongest risk factors for this disease, and this is a completely avoidable hazard. In addition, there are well described hereditary diseases which predispose, and familial pancreas cancer. We have sought here to summarise the role of tobacco-derived carcinogens and the mode of their tumorigenic action on the pancreas. There is compelling evidence from animal and human studies (laboratory including cell line studies and epidemiologic) that tobacco derived carcinogens cause pancreas cancer. However, the manner in which they do so is not entirely apparent. There is also compelling evidence that synergism with genetic and other life-style factors—like diet obesity—results in a multifactorial causation of the disease. Ascertaining the role of tobacco carcinogens in the development of this cancer and their interaction with other risk factors will enable novel therapeutic and preventative strategies to improve outcome from this appalling malignancy

Status of vitamin D, lipid profile and carotid artery intima media thickness in patients with chronic kidney disease stage III to V

Background: Chronic Kidney Disease (CKD) is characterized by irreversible sclerosis and loss of nephrons. The renal mass progressively declines over a prolonged period, depending on the underlying etiology. In CKD the most common feature is hypovitaminosis D which alter the vascular smooth muscle cell proliferation and reprogram the osteoblastic changes, finally leading to increase arterial wall thickness.Methods: A cross sectional study carried out over a 2-year period in Department Nephrology and General Medicine OPD, MIMS, Vizianagaram, Andhra Pradesh, India. 120 in which 60 are normal healthy individuals and 60 are CKD patients with stage 3 to 5. In all the participants serum creatinine, blood urea, serum triglycerides serum total cholesterol, HDL cholesterol estimated and serum 25 OH vitamin D are estimated.Results: The diagnostic criteria for CKD like blood urea, serum creatinine and eGFR were significantly higher in CKD when compared to control. In the present study, systolic and diastolic blood pressure was significantly increased in CKD compared with control. The Carotid Intima Media Thickness (CIMT) both left and right side were significant higher in CKD when compared with control. There is a significantly decreased levels of serum vitamin D in CKD (14.53 ng/mL±6.88) when compared with control (28.87 ng/mL±6.28).Conclusions: Present study finding suggested that there is a raised value of CIMT in CKD patients. High triglycerides, cholesterol and decreased HDL and declined vitamin D low hemoglobin, decreased eGFR, increased systolic blood pressure, raised CIMT value were found to be significantly increased in CKD patients