Helico-conical optical beams self-heal

An optical beam is said to be self-healing when, distorted by an obstacle, the beam corrects itself upon propagation. In this letter, we show through experiments supported by numerical simulations, that Helico-conical optical beams (HCOBs) self-heal. We observe the strong resilience of these beams with different types of obstructions, and relate this to the characteristics of their transverse energy flow.Comment: 4 pages, 5 figure

Field squeeze operators in optical cavities with atomic ensembles

We propose a method of generating unitarily single and two-mode field squeezing in an optical cavity with an atomic cloud. Through a suitable laser system, we are able to engineer a squeeze field operator decoupled from the atomic degrees of freedom, yielding a large squeeze parameter that is scaled up by the number of atoms, and realizing degenerate and non-degenerate parametric amplification. By means of the input-output theory we show that ideal squeezed states and perfect squeezing could be approached at the output. The scheme is robust to decoherence processes.Comment: Four pages and one figure. Accepted in Physical Review Letter

Potential cost-savings due to the application of a center of excellence care model in rheumatoid arthritis in Colombia

To evaluate the economic efficiency of a Center of Excellence (CoE) care model for rheumatic diseases located in Bogotá-Colombia. Biomab CoE is based on an adaptation of Colombian clinical practice guideline for the management of rheumatoid arthritis (RA). Care standards are defined by the severity of the disease (DAS28), involving an interdisciplinary team and differential types and frequencies of health services for each level of severity [remission, low (LDA), moderate (MDA) and severe disease activity (SDA)]. A cost-analysis was conducted to analyze the health economic impact after the application of a CoE model in a cohort of RA patients followed during a year. Mean, minimum, and maximum treatment costs were calculated at different moments in time: baseline, follow-up at month six, and after a year. This was done by multiplying the number of patients at each cut-off by the estimated cost per stage of the disease, according to the recommendations of the Colombian Institute of Health Technology Assessment. Statistical analyses were performed using Microsoft Excel® and R. All estimated costs were expressed in United States dollars, using the average exchange rate from January to December of 2018, reported by Banco de la República de Colombia: US$1=$2,951.3 Colombian pesos(COP). As preliminary results, 968 patients were followed during a year. At the beginning of the follow-up, treating all patients in the CoE with an integral attention would cost COP$1,808,096,027 ($1,440,179,796-$3,601,084,711). Same number of patients treated at month six of follow-up would cost COP$1,377,186,140 ($1,127,818,822-$2,570,342,964), and COP$1,147,370,864 ($949,470,612-$2,090,941,567) after a year of follow-up. Treating these patients in a CoE means potential cost-savings of up to COP$660,725,163 annually. As patients are treated in the CoE for RA, their health outcomes improve from severe disease activity status to low disease activity and remission, saving costs to the Colombian health system

The effect of the return of serve on the server pair’s movement parameters and rally outcome in padel using cluster analysis

Purpose: The pressure exerted on racket sports players by the service has been well documented. Whilst the return of serve has been suggested through qualitative interviews as being of similar importance there is a dearth of quantitative data to support this contention. This study analyzed time, speed, and distance parameters related to the outcome of the return of serve (ROS) in Padel, a sport similar to tennis but played on a court bounded by walls and played in doubles format only. Methods: Matches (n = 18) at two tournaments, sanctioned by the Valencian Federation, in 2012 were recorded and processed using Tracker software. ROS shot type (flat or lob), ball location, players’ positions on court and movement parameters between the ROS and the third shot of the server were captured 25 times per second. Results: Both lob and flat ROS produced six main clusters, as well as a small proportion of shots deemed outliers. The clusters differentiated shots played by two different level players (National and Regional), whether the ROS was played following a first or second serve, whether the serving pair adopted a conventional or Australian formation and whether the rally ended in a short number of shots (seven or less) or not. Conclusion: It was suggested that the aim of the ROS in Padel was to prevent the serving pair winning the rally quickly, since the advantage of the serve diminished after around 6 to 8 shots. This was best achieved by good depth on lobs, regardless of the direction, and pace on low shots, predominately aimed toward the server. This approach should be further modified to include the time between serve and ROS and consideration could be given to classifying attacking and defending positions

Evolution of E2 transition strength in deformed hafnium isotopes from new measurements on 172^{172}Hf, 174^{174}Hf, and 176^{176}Hf

The available data for E2 transition strengths in the region between neutron-deficient Hf and Pt isotopes are far from complete. More and precise data are needed to enhance the picture of structure evolution in this region and to test state-of-the-art nuclear models. In a simple model, the maximum collectivity is expected at the middle of the major shell. However, for actual nuclei, this picture may no longer be the case, and one should use a more realistic nuclear-structure model. We address this point by studying the spectroscopy of Hf. We remeasure the 2^+_1 half-lives of 172,174,176Hf, for which there is some disagreement in the literature. The main goal is to measure, for the first time, the half-lives of higher-lying states of the rotational band. The new results are compared to a theoretical calculation for absolute transition strengths. The half-lives were measured using \gamma-\gamma and conversion-electron-\gamma delayed coincidences with the fast timing method. For the determination of half-lives in the picosecond region, the generalized centroid difference method was applied. For the theoretical calculation of the spectroscopic properties, the interacting boson model is employed, whose Hamiltonian is determined based on microscopic energy-density functional calculations. The measured 2^+_1 half-lives disagree with results from earlier \gamma-\gamma fast timing measurements, but are in agreement with data from Coulomb excitation experiments and other methods. Half-lives of the 4^+_1 and 6^+_1 states were measured, as well as a lower limit for the 8^+_1 states. We show the importance of the mass-dependence of effective boson charge in the description of E2 transition rates in chains of nuclei. It encourages further studies of the microscopic origin of this mass dependence. New data on transition rates in nuclei from neighboring isotopic chains could support these studies.Comment: 16 pages, 16 figures, 7 tables; Abstract shortened due to character limi

Modelado numérico para estudiar interfases fluido-sólidas ante excitaciones dinámicas

ResumenEste trabajo trata sobre la propagación de ondas en interfases fluido-sólidas debidas a excitaciones dinámicas, que son conocidas como ondas de Scholte. Se ha estudiado una amplia gama de materiales sólidos elásticos empleados en la ingeniería. La interfase une un medio acústico (fluido) y otro sólido. Se ha demostrado que por medio de un análisis de ondas difractadas en un fluido es posible deducir las características mecánicas del medio sólido, específicamente sus velocidades de propagación. Para este propósito, el campo difractado de onda de presión y desplazamientos, debido a una onda inicial de presión en el fluido, se expresa mediante las representaciones integrales de frontera, las cuales satisfacen la ecuación de movimiento. La presión inicial en el fluido es representada mediante una función de Hankel de segunda especie y orden cero. La solución a este problema de propagación de ondas se obtiene por medio del método indirecto de elementos frontera, que es equivalente al bien conocido teorema de representación de Somigliana. La validación de los resultados se realiza por medio del método del número de onda discreto. En primer lugar, se muestran espectros de presiones que ilustran el comportamiento del fluido para cada material sólido considerado, y después se aplica la transformada rápida de Fourier para mostrar los resultados en el dominio del tiempo, donde se ejemplifica la aparición de las ondas de Scholte y la cantidad de energía que transportan.AbstractThis work shows the wave propagation in fluid-solid interfaces due to dynamic excitations, such interface waves are known as Scholte's waves. We studied a wide range of elastic solid materials used in engineering. The interface connects an acoustic medium (fluid) and another solid. It has been shown that by means of an analysis of diffracted waves in a fluid, it is possible to deduce the mechanical characteristics of the solid medium, specifically, its propagation velocities. For this purpose, the diffracted field of pressures and displacements, due to an initial pressure in the fluid, are expressed using boundary integral representations, which satisfy the equation of motion. The initial pressure in the fluid is represented by a Hankel's function of second kind and zero order. The solution to this problem of wave propagation is obtained by means of the Indirect Boundary Element Method, which is equivalent to the well-known Somigliana's representation theorem. The validation of the results was performed by means of the Discrete Wave Number Method. Firstly, spectra of pressures to illustrate the behavior of the fluid for each solid material considered are included, then, the Fast Fourier Transform algorithm to display the results in the time domain is applied, where the emergence of Scholte's waves and the amount of energy that they carry are highlighted

How expensive is treating patients in a center of excellence for rheumatoid arthritis in Colombia?

We aimed to estimate the cost of treating patients with rheumatoid arthritis (RA) in a Center of Excellence (CoE) for rheumatic diseases located in Bogotá, Colombia. We performed a cost analysis from the standard cost estimation of a CoE program for RA care. We estimated costs of consultations, laboratory and imaging tests, and pharmacological treatment from the measurement of the health care resource utilization of the CoE standard protocol according to the activity level of the disease (DAS28). Costing process was done following the recommendation of the Colombian Institute of Health Technology Assessment (IETS, in Spanish). Mean, minimum and maximum costs were reported annually for a type case depending on severity and classified as Remission, low disease activity (LDA), moderate disease activity (MDA) and severe disease activity -SDA- (with and without bDMARD). All costs were reported in American dollars, using the average exchange rate from January to December of 2018, reported by Banco de la República de Colombia: US$1 =$2,951.3 Colombian pesos. Mean total direct medical cost to treat a patient in remission is US$235.7 (213.0-336.4), in LDA is US325.2 (288.0-464.6) and in MDA is US$835.5 ($573.1-$2,187.1). There is a considerable increase in direct medical costs from a patient in SDA and SDA+Biologics: US$2,555.5 ($2,301.1-$3,890.9) to US$8,032.4 ($7,564.4-$8,400.3). The largest share of the cost was related to drugs, representing 39.9% for Remission, 53.6% for LDA, 75.2 for MDA, and in SDA and SDA+Biologics the proportion of what is spent on drugs for RA treatment is 88.5% and 96.7%, respectively. As the severity of the disease increases, the expenditure rate on drugs rises over the total of each activity level. With the introduction of the biological therapy, the treatment of RA is expensive, however, the CoE is an efficient way of care for RA