On Gravitational Energy in Newtonian Theories

There are well-known problems associated with the idea of (local) gravitational energy in general relativity. We offer a new perspective on those problems by comparison with Newtonian gravitation, and particularly geometrized Newtonian gravitation (i.e., Newton-Cartan theory). We show that there is a natural candidate for the energy density of a Newtonian gravitational field. But we observe that this quantity is gauge dependent, and that it cannot be defined in the geometrized (gauge-free) theory without introducing further structure. We then address a potential response by showing that there is an analogue to the Weyl tensor in geometrized Newtonian gravitation.Comment: 30 pages; derived from a paper presented at the 2016 UK/EU Foundations of Physics Conference in London, U

Prostate Cancer Microparticles in Men Undergoing Radical Prostatectomy

Objectives: To determine changes in prostate microparticle (PMP) concentrations in men with prostate cancer (PCa) after digital rectal examination (DRE), after radical prostatectomy (RP), and at follow-up. Materials and Methods: 22 men were recruited before RP. Four blood specimens were collected – baseline (specimen 1), post-DRE (specimen 2), immediately post-RP (specimen 3), and follow-up (specimen 4). Pre- and post-DRE urine was collected (Specimen A and B respectively). Flow cytometric analysis of biofluids was performed with fluorescent-labeled antibodies against prostate-specific membrane antigen (PSMA) and polysialic acid. Total MP (TMP) and dual positive (PMP) events per µl of plasma or urine were recorded. Results: Median TMPs from specimen 1 to 4 were 3 005 500, 1 600 600, 976 353, and 3 951 400 events/µl, respectively (p Conclusions: Proportional numbers of PMPs in men with PCa are significantly increased following DRE and RP

Conformal invariance of the Newtonian Weyl tensor

It is well-known that the conformal structure of a relativistic spacetime is of profound physical and conceptual interest. In this note, we consider the analogous structure for Newtonian theories. We show that the Newtonian Weyl tensor is an invariant of this structure

Pif1- and Exo1-dependent nucleases coordinate resection at uncapped telomeres

Telomeres are present at the ends of most eukaryotic chromosomes and are bound by specialized telomere ‘capping’ proteins, preventing them from initiating a DNA Damage Response and cell cycle arrest analogous to that triggered by DNA Double Strand Breaks (DSBs). Resection of ‘uncapped’ telomeres and DSBs to generate extensive single-stranded DNA (ssDNA) is one of the most upstream events in this DDR, but while the nuclease activities that resect DSBs are well-defined, only a single nuclease, Exo1, is known to function at uncapped telomeres. This work establishes that the helicase Pif1, is required for a nuclease activity that resects uncapped telomeres in a parallel pathway to one defined by Exo1, Rad27 (Flap Endonuclease 1) and Rad24 (the 9-1-1 clamp loader). Following inactivation of the essential telomere capping protein Cdc13, Pif1 is shown to resect telomeres independently of Exo1 close to the chromosome end, but to play a less-crucial role in extensive resection. Furthermore, elimination of both Pif1 and Exo1 prevents the accumulation of ssDNA, thus eliminating the DDR at uncapped telomeres. Although Pif1 has no role in the resection of DSBs and has primarily been studied as a negative regulator of telomerase, it is shown to contribute to the DDR at uncapped telomeres in cells lacking telomerase and also to be crucial for telomere maintenance in telomerasedeficient cells. Cdc13 inhibits the DDR at uncapped telomeres and is believed to be required for telomerase recruitment. Astonishingly, elimination of Pif1 and Exo1 permits the viability of cells lacking Cdc13 and cdc13Δ exo1Δ pif1Δ mutants maintain and lengthen their telomeres over time, in a manner dependent on Ku, Rad52 and telomerase. Thus, Cdc13 is not a requirement for telomerase recruitment and elimination of the nuclease activities that function at uncapped telomeres can by pass the requirement for otherwise-essential telomere capping proteins.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigating racial differences in clinical and pathological features of prostate cancer in South African men

The aim of this project is to study the clinical and pathological features of prostate cancer in men from different racial groups in the Western Cape in an attempt to define the characteristics of the disease locally. Specifically we wanted to compare black with coloured and white patients

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