334 research outputs found
Surface-Gravity Inequalities and Generic Conditions for Strong Cosmic Censorship
Transforming Penrose's intuitive picture of a strong cosmic censorship
principle, that generically forbids the appearance of locally naked space-time
singularities, into a formal mathematical proof, remains at present, one of the
most outstanding unsolved mathematical problems from the theory of
gravitational collapse. Part of the difficulty lies in the fact that we do not
possess yet a clear-cut understanding of the hypothesis needed for the
establishment of some sort of strong cosmic censorship theorem. What we have is
a selected list of solutions, which at first sight seem to go against cosmic
censorship, but at the end they fail in some way. However, the space of
solutions of Einstein's field equations is vast. In this article, we plan to
increase one's intuition by establishing a link between certain inequalities
for Cauchy-horizon stability and a set of generic conditions, such as a
reasonable equation of state--which determines whether the space-time is
asymptotically flat or not, an energy condition, and an hypothesis over the
class of metrics on which Einstein's field equations ought to be solved to
ensure strong cosmic censorship inside black-holes. With these tools in hand we
examine the Cauchy-horizon stability of the theory created by Born and
Infeld--whose action principle has been used as a prototype in superstring
theory, and the singularity-free Bardeen's black-hole model.Comment: 6 pages, 2 figures(type eps), REVTeX
Renin-angiotensin-aldosterone system-based antihypertensive agents and the risk of colorectal cancer among medicare beneficiaries
Background: Biologic evidence suggests that angiotensin II may play a role in tumor progression or growth. We compared the short-term colorectal cancer (CRC) risk among initiators of angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) versus guideline-recommended clinical alternatives (beta blockers, calcium channel blockers [CCB], and thiazides). Methods: We conducted a new-user cohort study on U.S. Medicare beneficiaries aged over 65 years, who initiated antihypertensive monotherapy during 2007-2013 and were free of cancer diagnosis before drug initiation. Follow-up began 6 months postinitiation to allow time for the diagnostic delay. We estimated hazard ratios (HR) with 95% confidence intervals (CI) using propensity score weighted Cox regression, overall and stratified by time since drug initiation, and 5-year cumulative risk differences (RD) using Kaplan-Meier estimator. We assessed the potential for unmeasured confounding using supplemental data from Medicare Current Beneficiary Survey. Results: For analyses without censoring for treatment changes, we observed 532 CRC events among 111,533 ACEI/ARB initiators. After a median follow-up of 2.2 years (interquartile range: 1.0-3.7), CRC risk was similar between ACEI/ARB and active comparators, with adjusted HRs of 1.0 (95% CI = 0.85, 1.1) for ACEI/ARB versus beta blockers, 1.2 (95% CI = 0.97, 1.4) for ACEI/ARB versus CCB and 1.0 (95% CI = 0.80, 1.3) for ACEI/ARB versus thiazide. Five-year RDs and as-treated analyses, which censored follow-up at medication changes, produced similar findings. Conclusions: Based on real-world antihypertensive utilization patterns in Medicare beneficiaries, our study suggests no association between ACEI/ARB initiation and the short-term CRC risk
Bibbia, cristianesimo e letteratura italiana: uno sguardo d'assieme.
L'A. ripercorre la presenza della Bibbia nella letteratura italiana dalle origini ai giorni nostri, sottolineando la persistenza della ripresa del Sacro testo sia nella poesia che nella prosa
A radium assay technique using hydrous titanium oxide adsorbent for the Sudbury Neutrino Observatory
As photodisintegration of deuterons mimics the disintegration of deuterons by
neutrinos, the accurate measurement of the radioactivity from thorium and
uranium decay chains in the heavy water in the Sudbury Neutrino Observatory
(SNO) is essential for the determination of the total solar neutrino flux. A
radium assay technique of the required sensitivity is described that uses
hydrous titanium oxide adsorbent on a filtration membrane together with a
beta-alpha delayed coincidence counting system. For a 200 tonne assay the
detection limit for 232Th is a concentration of 3 x 10^(-16) g Th/g water and
for 238U of 3 x 10^(-16) g U/g water. Results of assays of both the heavy and
light water carried out during the first two years of data collection of SNO
are presented.Comment: 12 pages, 4 figure
Probing the limit of nuclear existence: Proton emission from 159Re
AbstractThe observation of the new nuclide 15975Re84 provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised in the reaction 106Cd(58Ni, p4n) and identified via its proton radioactivity using the ritu gas-filled separator and the great focal-plane spectrometer. Comparisons of the measured proton energy (Ep=1805±20 keV) and decay half-life (t1/2=21±4 μs) with values calculated using the WKB method indicate that the proton is emitted from an h11/2 state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered
Clinical outcome 10 years after attempted percutaneous transluminal coronary angioplasty in 856 patients.
Abstract
OBJECTIVES: This study reports the 10-year outcome of 856 consecutive patients who underwent attempted coronary angioplasty at the Thoraxcenter during the years 1980 to 1985.
BACKGROUND: Coronary balloon angioplasty was first performed in 1977, and this procedure was introduced into clinical practice at the Thoraxcenter in 1980. Although advances have been made, extending our knowledge of the long-term outcome in terms of survival and major cardiac events remains of interest and a valuable guide in the treatment of patients with coronary artery disease.
METHODS: Details of survival, cardiac events, symptoms and medication were retrospectively obtained from the Dutch civil registry, medical records or by letter or telephone or from the patient's physician and entered into a dedicated data base. Patient survival curves were constructed, and factors influencing survival and cardiac events were identified.
RESULTS: The procedural clinical success rate was 82%. Follow-up information was obtained in 837 patients (97.8%). Six hundred forty-one patients (77%) were alive, of whom 334 (53%) were symptom free, and 254 (40%) were taking no antianginal medication. The overall 5- and 10-year survival rates were 90% (95% confidence interval [CI] 87.6% to 92.4%) and 78% (95% CI 75.0% to 81.0%), respectively, and the respective freedom from significant cardiac events (death, myocardial infarction, coronary artery bypass surgery and repeat angioplasty) was 57% (95% CI 53.4% to 60.6%) and 36% (95% CI 32.4% to 39.6%). Factors that were found to adversely influence 10-year survival were age > or = 60 years (> or = 60 years [67%], 50 to 59 years [82%], or = 50% [80%]) and a history of previous myocardial infarction (previous myocardial infarction [72%], no previous infarction [83%]). These factors were also found to be independent predictors of death during the follow-up period by a multivariate stepwise logistic regression analysis. Other factors tested, with no influence on survival, were gender, procedural success and stability of angina at the time of intervention.
CONCLUSIONS: The long-term prognosis of patients after coronary angioplasty is good, particularly in those <60 years old with single-vessel disease and normal left ventricular function. The majority of patients are likely to experience a further cardiac event in the 10 years after their first angioplasty procedure
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Energetic particle influence on the Earth's atmosphere
This manuscript gives an up-to-date and comprehensive overview of the effects of energetic particle precipitation (EPP) onto the whole atmosphere, from the lower thermosphere/mesosphere through the stratosphere and troposphere, to the surface. The paper summarizes the different sources and energies of particles, principally
galactic cosmic rays (GCRs), solar energetic particles (SEPs) and energetic electron precipitation (EEP). All the proposed mechanisms by which EPP can affect the atmosphere
are discussed, including chemical changes in the upper atmosphere and lower thermosphere, chemistry-dynamics feedbacks, the global electric circuit and cloud formation. The role of energetic particles in Earth’s atmosphere is a multi-disciplinary problem that requires expertise from a range of scientific backgrounds. To assist with this synergy, summary tables are provided, which are intended to evaluate the level of current knowledge of the effects of energetic particles on processes in the entire atmosphere
A somatic-mutational process recurrently duplicates germline susceptibility loci and tissue-specific super-enhancers in breast cancers
Somatic rearrangements contribute to the mutagenized landscape of cancer genomes. Here, we systematically interrogated rearrangements in 560 breast cancers by using a piecewise constant fitting approach. We identified 33 hotspots of large (>100 kb) tandem duplications, a mutational signature associated with homologous-recombination-repair deficiency. Notably, these tandem-duplication hotspots were enriched in breast cancer germline susceptibility loci (odds ratio (OR) = 4.28) and breast-specific 'super-enhancer' regulatory elements (OR = 3.54). These hotspots may b
Breast cancer metastasis to gynaecological organs: a clinico-pathological and molecular profiling study
Breast cancer metastasis to gynaecological organs is an understudied pattern of tumour spread. We explored clinico-pathological and molecular features of these metastases to better understand whether this pattern of dissemination is organotropic or a consequence of wider metastatic dissemination. Primary and metastatic tumours from 54 breast cancer patients with gynaecological metastases were analysed using immunohistochemistry, DNA copy-number profiling, and targeted sequencing of 386 cancer-related genes. The median age of primary tumour diagnosis amongst patients with gynaecological metastases was significantly younger compared to a general breast cancer population (46.5 versus 60 years; p < 0.0001). Median age at metastatic diagnosis was 54.4, time to progression was 4.8 years (range 0-20 years), and survival following a diagnosis of metastasis was 1.95 years (range 0-18 years). Patients had an average of five involved sites (most frequently ovary, fallopian tube, omentum/peritoneum), with fewer instances of spread to the lungs, liver, or brain. Invasive lobular histology and luminal A-like phenotype were over-represented in this group (42.8 and 87.5%, respectively) and most patients had involved axillary lymph nodes (p < 0.001). Primary tumours frequently co-expressed oestrogen receptor cofactors (GATA3, FOXA1) and harboured amplifications at 8p12, 8q24, and 11q13. In terms of phenotype conversion, oestrogen receptor status was generally maintained in metastases, FOXA1 increased, and expression of progesterone receptor, androgen receptor, and GATA3 decreased. ESR1 and novel AR mutations were identified. Metastasis to gynaecological organs is a complication frequently affecting young women with invasive lobular carcinoma and luminal A-like breast cancer, and hence may be driven by sustained hormonal signalling. Molecular analyses reveal a spectrum of factors that could contribute to de novo or acquired resistance to therapy and disease progression.Jamie R Kutasovic, Amy E McCart Reed, Renique Males, Sarah Sim, Jodi M Saunus ... Liana Dedina ... et al
ResĂduos de estações de tratamento de água e a ISO 24512: desafio do saneamento brasileiro
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