3,532 research outputs found
Extremal states for photon number and quadratures as gauges for nonclassicality
Rotated quadratures carry the phase-dependent information of the
electromagnetic field, so they are somehow conjugate to the photon number. We
analyze this noncanonical pair, finding an exact uncertatinty relation, as well
as a couple of weaker inequalities obtained by relaxing some restrictions of
the problem. We also find the intelligent states saturating that relation and
complete their characterization by considering extra constraints on the
second-order moments of the variables involved. Using these moments, we
construct performance measures tailored to diagnose photon-added and
Schr\"odinger catlike states, among others.Comment: 6 pages, 4 color figures. Comments welcome
Unpolarized states and hidden polarization
We capitalize on a multipolar expansion of the polarisation density matrix,
in which multipoles appear as successive moments of the Stokes variables. When
all the multipoles up to a given order vanish, we can properly say that the
state is th-order unpolarized, as it lacks of polarization information to
that order. First-order unpolarized states coincide with the corresponding
classical ones, whereas unpolarized to any order tally with the quantum notion
of fully invariant states. In between these two extreme cases, there is a rich
variety of situations that are explored here. The existence of \textit{hidden}
polarisation emerges in a natural way in this context.Comment: 7 pages, 3 eps-color figures. Submitted to PRA. Comments welcome
Orbital angular momentum from marginals of quadrature distributions
We set forth a method to analyze the orbital angular momentum of a light
field. Instead of using the canonical formalism for the conjugate pair
angle-angular momentum, we model this latter variable by the superposition of
two independent harmonic oscillators along two orthogonal axes. By describing
each oscillator by a standard Wigner function, we derive, via a consistent
change of variables, a comprehensive picture of the orbital angular momentum.
We compare with previous approaches and show how this method works in some
relevant examples.Comment: 7 pages, 2 color figure
Correction: Understanding MAOS through computational chemistry
Correction for 'Understanding MAOS through computational chemistry' by P. Prieto et al., Chem. Soc. Rev., 2017, 46, 431–451
On the Detection of CMB B-modes from Ground at Low Frequency
The primordial CMB -mode search is on the spotlight of the scientific
community due to the large amount of cosmological information that is encoded
in the primeval signal. However, the detection of this signal is challenging
from the data analysis point of view, due to the relative low amplitude
compared to the foregrounds, the lensing contamination coming from the leakage
of -modes, and the instrumental noise. Here, we studied the viability of the
detection of the primordial polarization -mode with a ground-based telescope
operating in the microwave low-frequency regime (i.e., from 10GHz-120GHz) in a
handful of different scenarios: i. the instrument's channels distribution and
noise, ii. the tensor-to-scalar ratio () detectability considering different
possible values and degrees of delensing, iii. the effect of including a
possible source of polarized anomalous microwave emission (AME), iv. the
strengths and weaknesses of different observational strategies and, v. the
atmospheric and systematic noise impact on the recovery. We focused mainly on
the removal of galactic foregrounds as well as noise contamination by applying
a full-parametric pixel-based maximum likelihood component separation
technique. Moreover, we developed a numerical methodology to estimate the
residuals power spectrum left after component separation, which allow us to
mitigate possible biases introduced in the primordial -mode power spectrum
reconstruction. Among many other results, we found that this sort of experiment
is capable of detecting Starobinsky's even when no delensing is performed
or, a possible polarized AME contribution is taken into account. Besides, we
showed that this experiment is a powerful complement to other on-ground or
satellite missions, such as LiteBIRD, since it can help significantly with the
low-frequency foregrounds characterization.Comment: 28 pages, 18 figures, submitted to JCA
Lost and found: the radial quantum number of Laguerre-Gauss modes
We introduce an operator linked with the radial index in the Laguerre-Gauss
modes of a two-dimensional harmonic oscillator in cylindrical coordinates. We
discuss ladder operators for this variable, and confirm that they obey the
commutation relations of the su(1,1) algebra. Using this fact, we examine how
basic quantum optical concepts can be recast in terms of radial modes.Comment: Some minor typos fixed
Influence of Polarity and Activation Energy in Microwave-Assisted Organic Synthesis (MAOS)
The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20-30 kcal mol-1 and a polarity (µ) between 7-20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation
Evaluation of the national vaccination day in bogotá, d.c., 2001
Objectives: A national immunization day-NID, aimed at improving vaccination coverage, was carried out in Colombia in November 2001. The main objective of the study was to measure the proportion of children under 2 years either completing their immunization schedule or advancing through it by receiving doses during the NID. Besides, we also evaluated the proportion of lost opportunities for vaccination during the NID and the impact of the media (TV, radio, newspapers, etc.) in advertising the NID. Methods: In order to evaluate the impact of immunization a cross sectional survey was carried out in Bogotá in the waiting rows of the 30 randomly selected vaccination posts; 623 participants were systematically chosen. The outcomes were analyzed by age, socioeconomic level and type of health insurance-SSS. Only children holding a vaccination card were considered eligible for the study. Results: Most people become aware about NID through TV, 81 %, followed by radio advertisements, 22 %. After attending NID the proportion of fully vaccinated children, according to PAHO scheme, raised from 46 % to 66 %, a 43 % increase. This increase was even higher among children aged less than 6 months (140 % increment). There were no differences in the increment by social stratum or affiliation to the SSS. Among the children studied we identified a 24 % of loss opportunities for vaccination that did not differ by socioeconomic level or SSS groups. Conclusions: Our results suggest that, despite its high costs, NID might be useful to transiently overcome barriers for adequate access to health services.Objetivos: Durante Noviembre de 2001 se realizó una jornada de vacunación en Bogotá con el fin de mejorar coberturas. El objetivo principal era medir la proporción de niños menores de 2 años que finalizaban el esquema o que avanzaban en el esquema por dosis recibidas durante la jornada. Adicionalmente se midió la proporción de oportunidades perdidas de vacunación-OPV durante la jornada y el impacto de los diferentes medios de comunicación usados para anunciar la realización de la jornada. Métodos: Se diseñó un estudio transversal con encuesta rápida en las filas de espera de los puestos de vacunación. Todos los indicadores fueron relacionados con variables socioeconómicas como la edad del niño, el estrato socioeconómico y el tipo de afiliación al sistema de salud-SGSS. Fueron seleccionados al azar 30 puestos de vacunación y se escogieron 623 participantes con carné de vacunación. Resultados: El medio masivo con mayor impacto fue la televisión, 81 %, seguido por la radio con 22 %. El porcentaje de niños con esquema completo de OPS pasó de 46 a 63 %, incremento de 43 %, siendo mayor en los menores de 6 meses (incremento de 140 %). No hubo diferencias en el incremento por estrato socioeconómico o tipo de afiliación al SGSS. Se registró un 24 % de OPV que tampoco fue diferente por estrato socioeconómico o afiliación al SGSS. Conclusiones: Los resultados sugieren que, pese a su alto costo, las jornadas de vacunación pueden ser útiles para remover transitoriamente las barreras de acceso a los servicios de salud
Prevalence of four statin benefit groups in a population of the Caribbean region of Colombia
Objectives: To estimate the prevalence of four Statin Benefit Groups (SBG) according to the 2018 ACC/AHA Multisociety Guideline on the Management of Blood Cholesterol, in a population of the Caribbean region of Colombia enrolled to DTC program Mutual SER-EPS in 2015 Methods: Data on a history of hyperlipidemia was collected by study investigators at including adults patients enrolled to DTC program Mutual SER-EPS in 2015 (N = 64,667) with ICD-10 diagnosis of hyperlipidemia (E78), or with a personal history of hyperlipidemia; or with abnormal lipid profile; or patients under treatment with lipid-lowering drugs. The four SBG were comprised adult patients 21 years of age with LDL-C 20% as determined by the Framingham Risk Score (SBG4). The prevalence of statin use by SBG and factors associated with statin use were estimated. Results: The prevalence of SBG1, SBG2, SBG3 and SBG4 in patients enrolled to DTC program Mutual SER-EPS in 2015 were 4.6% (2,985), 0.5% (337), 2.5% (1,633) and 1.3% (891), respectively. The prevalence of statin use in SBG1, SBG2, SBG3 and SBG4 were 69.1% (2,064), 40.6% (137), 47% (768) and 59.1% (463), respectively. Arterial hypertension (OR: 2.70; 95% IC 1.70-4.28) and personal history of ASCVD (OR: 3.43; 95% IC 2.15-5.46) were very significantly associated with statin use. Conclusions: The prevalence of SBG and statin use in patients enrolled to DTC program Mutual SEREPS in 2015 were 9% (5,846) and 58.7% (3,432), respectively
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