143 research outputs found
P-P Total Cross Sections at VHE from Accelerator Data
Comparison of P-P total cross-sections estimations at very high energies -
from accelerators and cosmic rays - shows a disagreement amounting to more than
10 %, a discrepancy which is beyond statistical errors. Here we use a
phenomenological model based on the Multiple-Diffraction approach to
successfully describe data at accelerator energies. The predictions of the
model are compared with data On the basis of regression analysis we determine
confident error bands, analyzing the sensitivity of our predictions to the
employed data for extrapolation. : using data at 546 and 1.8 TeV, our
extrapolations for p-p total cross-sections are only compatible with the Akeno
cosmic ray data, predicting a slower rise with energy than other cosmic ray
results and other extrapolation methods. We discuss our results within the
context of constraints in the light of future accelerator and cosmic ray
experimental results.Comment: 26 pages aqnd 11 figure
Analytic models and forward scattering from accelerator to cosmic-ray energies
Analytic models for hadron-hadron scattering are characterized by analytical
parametrizations for the forward amplitudes and the use of dispersion relation
techniques to study the total cross section and the
parameter. In this paper we investigate four aspects related to the application
of the model to and scattering, from accelerator to cosmic-ray
energies: 1) the effect of different estimations for from
cosmic-ray experiments; 2) the differences between individual and global
(simultaneous) fits to and ; 3) the role of the
subtraction constant in the dispersion relations; 4) the effect of distinct
asymptotic inputs from different analytic models. This is done by using as a
framework the single Pomeron and the maximal Odderon parametrizations for the
total cross section. Our main conclusions are the following: 1) Despite the
small influence from different cosmic-ray estimations, the results allow us to
extract an upper bound for the soft pomeron intercept: ;
2) although global fits present good statistical results, in general, this
procedure constrains the rise of ; 3) the subtraction constant as
a free parameter affects the fit results at both low and high energies; 4)
independently of the cosmic-ray information used and the subtraction constant,
global fits with the odderon parametrization predict that, above GeV, becomes greater than , and
this result is in complete agreement with all the data presently available. In
particular, we infer at GeV and
at 500 GeV (BNL RHIC energies).Comment: 16 pages, 7 figures, aps-revtex, wording changes, corrected typos, to
appear in Physical Review
Helicobacter pylori in dyspeptic children and adults: endoscopic, bacteriologic and histologic correlations
Degradation and detoxification of synthetic dyes and textile industry effluents by newly isolated Leptosphaerulina sp. from Colombia
Casemix, management, and mortality of patients receiving emergency neurosurgery for traumatic brain injury in the Global Neurotrauma Outcomes Study: a prospective observational cohort study
THE SERO-CONVERSION AND EVALUATION OF RENAL ALTERATIONS IN DOGS INFECTED BY Leishmania (Infantum) chagasi
Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.
BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700
Como incluir características dos distritos do município de São Paulo em estudos epidemiológicos?: análise da desigualdade de renda pelo uso do propensity score matching
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