ABSTRACT
Pseudo-random number generators are widely used in many branches of science, mainly in applications related to Monte Carlo methods, although they are deterministic in design and, therefore, unsuitable for tackling fundamental problems in security and cryptography. The natural laws of the microscopic realm provide a fairly simple method to generate non-deterministic sequences of random numbers, based on measurements of quantum states. In practice, however, the experimental devices on which quantum random number generators are based are often unable to pass some tests of randomness. In this review, we briefly discuss two such tests, point out the challenges that we have encountered in experimental implementations and finally present a fairly simple method that successfully generates non-deterministic maximally random sequences.
ABSTRACT
Random number generation plays an essential role in technology with important applications in areas ranging from cryptography to Monte Carlo methods, and other probabilistic algorithms. All such applications require high-quality sources of random numbers, yet effective methods for assessing whether a source produce truly random sequences are still missing. Current methods either do not rely on a formal description of randomness (NIST test suite) on the one hand, or are inapplicable in principle (the characterization derived from the Algorithmic Theory of Information), on the other, for they require testing all the possible computer programs that could produce the sequence to be analysed. Here we present a rigorous method that overcomes these problems based on Bayesian model selection. We derive analytic expressions for a model's likelihood which is then used to compute its posterior distribution. Our method proves to be more rigorous than NIST's suite and Borel-Normality criterion and its implementation is straightforward. We applied our method to an experimental device based on the process of spontaneous parametric downconversion to confirm it behaves as a genuine quantum random number generator. As our approach relies on Bayesian inference our scheme transcends individual sequence analysis, leading to a characterization of the source itself.
ABSTRACT
Objetivos: Identificar los factores asociados a Delirio entre los pacientes de la Unidad de Cuidados Intensivos del Hospital Nacional Hipólito Unanue en el periodo comprendido entre Octubre a Diciembre del 2013. Material y métodos: Se realizó un estudio analítico de 58 pacientes ingresados a la Unidad de Cuidados Intensivos del Hospital Nacional Hipólito Unanue en el periodo que corresponde al estudio. Resultados: el 36,2 por ciento de pacientes ingresados a la unidad de cuidados intensivos presento delirio, y el 63,8 por ciento no presento delirio. La media de la edad global fue de 57,0+/-7,7 años, siendo la mínima de 45 años y la máxima de 73 años. De los pacientes que presentaron delirio el 57,1 por ciento fueron varones y el 42,9 por ciento mujeres. (P>0,05) Los pacientes que presentaron delirio tuvieron una mayor media de días de ventilación mecánica (8,1 versus 6,3 días). (P<0,05) Los pacientes que presentaron delirio tuvieron una mayor media de puntuación APACHE al ingreso (17,7 versus 13,5). (P<0,05). Los pacientes que presentaron delirio tuvieron una mayor media de días de permanencia en la unidad de cuidados intensivos (11,0 versus 9,1) (P<0,05). Los pacientes que presentaron delirio tuvieron una mayor media de días de hospitalización (14,5 versus 12,2) (P<0,05). El 14,3 por ciento fallecieron. Encontramos una asociación estadísticamente significativa de delirio con trauma (P<0,05). Conclusiones: los factores asociados a delirio fueron: los días de ventilación, score APACHE al ingreso, días de permanencia en la UCI, días de hospitalización, y el trauma como patología de ingreso.
Objectives: To identify factors associated with delirium among patients in the Intensive Care Unit of National Hospital Hipolito Unanue in the period from October to December 2013. Material and Methods: An analytical study of 58 patients admitted to the ICU of National Hospital Hipolito Unanue in the period being the study was conducted. Results: 36.2 per cent of patients admitted to the intensive care unit delirium present, and 63.8 per cent did not present delirium. The global mean age was 57.0+/-7.7 years, with a minimum of 45 and maximum of 73 years. Of the patients who developed delirium 57.1 per cent were male and 42.9 per cent female (P>0.05). Patients who developed delirium had a higher mean number of days of mechanical ventilation (8.1 versus 6.3 days). (P<0.05) Patients who developed delirium had a higher mean APACHE II score at admission (17.7 versus 13.5). (P<0.05) Patients who developed delirium had a higher mean number of days spent in the intensive care unit (11.0 versus 9.1). (P<0.05) Patients who developed delirium had a higher mean number of days of hospitalization (14.5 versus 12.2) (P<0.05). 14.3 per cent died. We found a statistically significant association between delirium trauma (P<0.05). Conclusions: factors associated with delirium were the days of ventilation, APACHE score at admission, days spent in the ICU, hospital days, and trauma and pathology of income.
