Determination of transition frequencies in a single 138^{138}Ba+^{+} ion

Transition frequencies between low-lying energy levels in a single trapped $^{138}$Ba$^{+}$ ion have been measured with laser spectroscopy referenced to an optical frequency comb. By extracting the frequencies of one-photon and two-photon components of the line shape using an eight-level optical Bloch model, we achieved 0.1 MHz accuracy for the 5d $^{2}$D$_{3/2}$ - 6p $^{2}$P$_{1/2}$ and 6s $^{2}$S$_{1/2}$ - 5d $^{2}$D$_{3/2}$ transition frequencies, and 0.2 MHz for the 6s $^{2}$S$_{1/2}$ - 6p $^{2}$P$_{1/2}$ transition frequency.Comment: 5 pages, 7 figures, submitted to Phys. Rev.

Nonstationarities in the occurrence rates of flood events in Portuguese watersheds

An exploratory analysis on the variability of flood occurrence rates in 10 Portuguese watersheds is made, to ascertain if that variability is concurrent with the principle of stationarity. A peaks-over-threshold (POT) sampling technique is applied to 10 long series of mean daily streamflows and to 4 long series of daily rainfall in order to sample the times of occurrence (POT time data) of the peak values of those series. The kernel occurrence rate estimator, coupled with a bootstrap approach, was applied to the POT time data to obtain the time dependent estimated occurrence rate curves, λ<span style="position: relative; margin-left: -0.45em; top: -0.3em;">ˆ</span>(<i>t</i>), of floods and extreme rainfall events. The results of the analysis show that the occurrence of those events constitutes an inhomogeneous Poisson process, hence the occurrence rates are nonstationary. An attempt was made to assess whether the North Atlantic Oscillation (NAO) casted any influence on the occurrence rate of floods in the study area. Although further research is warranted, it was found that years with a less-than-average occurrence of floods tend to occur when the winter NAO is in the positive phase, and years with a higher occurrence of floods (more than twice the average) tend to occur when the winter NAO is in the negative phase. Although the number of analyzed watersheds and their uneven spatial distribution hinders the generalization of the findings to the country scale, the authors conclude that the mathematical formulation of the flood frequency models relying on stationarity commonly employed in Portugal should be revised in order to account for possible nonstationarities in the occurrence rates of such events

Extreme mechanical resilience of self-assembled nanolabyrinthine materials

Low-density materials with tailorable properties have attracted attention for decades, yet stiff materials that can resiliently tolerate extreme forces and deformation while being manufactured at large scales have remained a rare find. Designs inspired by nature, such as hierarchical composites and atomic lattice-mimicking architectures, have achieved optimal combinations of mechanical properties but suffer from limited mechanical tunability, limited long-term stability, and low-throughput volumes that stem from limitations in additive manufacturing techniques. Based on natural self-assembly of polymeric emulsions via spinodal decomposition, here we demonstrate a concept for the scalable fabrication of nonperiodic, shell-based ceramic materials with ultralow densities, possessing features on the order of tens of nanometers and sample volumes on the order of cubic centimeters. Guided by simulations of separation processes, we numerically show that the curvature of self-assembled shells can produce close to optimal stiffness scaling with density, and we experimentally demonstrate that a carefully chosen combination of topology, geometry, and base material results in superior mechanical resilience in the architected product. Our approach provides a pathway to harnessing self-assembly methods in the design and scalable fabrication of beyond-periodic and nonbeam-based nano-architected materials with simultaneous directional tunability, high stiffness, and unsurpassed recoverability with marginal deterioration

Evaluation of the Stiffness Effect of Pipe Supports in Relation to Static and Dynamic Loads in a Flexibility Analysis

Piping flexibility analysis is done to ensure structural integrity in all operating conditions that may occur over the life of a system, whether static or dynamic. In industrial designs generally the rigidity of the support is neglected in the analysis of flexibility. The work presents an evaluation of the loads transmitted the structures in function of the rigidity of the pipe support. The evaluation was done through computer simulation using finite element techniques. The computational simulation made possible the evaluation of the forces transmitted to the support structures of an existing project of an orifice station, when considering the rigidity of the support. The work also shows that it is possible to refine projects when taken into consideration the influence of the rigidity of the supports, making a more adequate sizing the structure, portraying more faithfully the behavior of the system. The work also evaluates the influence, advantages and disadvantages in the use of stiffness in the supports with regard to the load transmitted to the support structures (support, base and tube)

Stress Analysis on a “L” shape Truss Optimization

The metal construction market in Brazil has grown significantly over the past few years. The weight reductions and performance increase of mechanical pieces obtained by using optimization techniques are significant to the point that currently its use is critical to define that competitiveness of the metal-mechanical engineering industries, and its undeniable importance in reducing costs. The optimization applied in the mechanical part design consists of using computational methods for dimensions, shape or optimal topology of parts. This study aims to propose a study methodology to analyse the stress distribution thought the use of mathematical software and photoelasticity techniques, to propose a new structural profile, lighter and more efficient, which may be used as solution to overcome the current constructive limitations

Impact of the economic crisis in the approval of new oncological drugs:the Portuguese paradigm

Background: The European crisis lead to funding restrains in healthcare, already under pressure due to the ageing of the population and the increase of demands from innovation. Portugal is the paradigm of the European crisis since has both an economic and demographic crisis. The researchers aimed to evaluate the impact of economic restrains in Portugal for access and reimbursement of new oncological drugs. Methodology: A qualitative approach was used, supported by 27 formal, tape recorded, semi-structured interviews to representatives of the different healthcare stakeholders and policymakers. The content analysis with semantic associations through co-occurrence analysis were done with the support of Tropes® software. Results: The results of the content analysis showed that economic restrains are leading to a policy of cost control with lower prices and reduced access to innovation; an excessive delay in the approval of new drugs; lack of transparency; serious limitations and inequity between hospitals. Contractual boundaries to national prescription was established and agreements with pharmaceuticals were made. Changes in the reimbursement process are being implemented with an increase of risk sharing mechanisms and implementation of a new system of health technological evaluation (SINATS). Treatment protocols are also being revised and public hospitals are trying to increase the number of clinical trials but there is still much bureaucracy. In this qualitative approach, the following factors with impact on survival were identified: Innovation and technological development, government funding, the price of drugs and type of oncological diseases. Conclusions: The economic crisis is leading to a very serious problem of inequity. However, it is also an opportunity for a structural reform. In Portugal, an attempt of reform is being made with the implementation of SINATS since it is important to distinguish molecules that effectively bring added value. In order to consider the strategic vision in which the patient is the center of all efforts, the process of reimbursement approval for new medicines should be faster, more transparent and interdisciplinary. Moreover, the decisions must be done triangulating evidence based medicine, economics, health policy and ethical and legal issues. For National Health Service sustainability, efficiency and efficacy, clinical and economic reassessments must be done after market introduction of new medicines, with subsequent renegotiations.info:eu-repo/semantics/publishedVersio

Returns to Tenure or Seniority

This study documents two empirical facts using matched employer-employee data for Denmark and Portugal. First, workers who are hired last, are the first to leave the firm. Second, workers' wages rise with seniority (= a worker's tenure relative to the tenure of her colleagues). The identification problems for the wage return to tenure are shown not to apply to the return to seniority because seniority is not a deterministic function of time. Controlling for tenure, the probability of leaving the firm decreases with seniority. The increase in expected seniority with tenure explains a large part of the negative duration dependence of the hazard. Using a variety of estimation methods, we show that a 10% increase in seniority raises your wage by 0.1-0.2%, depending on the country and the method applied. Conditional on ten years of tenure, one standard deviation of seniority raises your wage by 0.5 to 1.6 percent. Forthcoming in Econometrica

Measurement of the branching ratio for beta-delayed alpha decay of 16N

While the 12C(a,g)16O reaction plays a central role in nuclear astrophysics, the cross section at energies relevant to hydrostatic helium burning is too small to be directly measured in the laboratory. The beta-delayed alpha spectrum of 16N can be used to constrain the extrapolation of the E1 component of the S-factor; however, with this approach the resulting S-factor becomes strongly correlated with the assumed beta-alpha branching ratio. We have remeasured the beta-alpha branching ratio by implanting 16N ions in a segmented Si detector and counting the number of beta-alpha decays relative to the number of implantations. Our result, 1.49(5)e-5, represents a 24% increase compared to the accepted value and implies an increase of 14% in the extrapolated S-factor