Accurate circuit analysis of resonant-type left handed transmission lines with inter-resonator coupling

In this paper, a circuit model for the description of left handed transmission lines based on complementary split rings resonators CSRRs is proposed. As compared to previous models, coupling between adjacent resonators is included in the present work. The conditions that make this coupling significant are discussed. Specifically, it will be shown that it is barely present when circular CSRRs are used to implement the left handed transmission line. However, if the line is loaded with rectangular CSRRs separated by a small distance, inter-resonator coupling is important and it significantly influences the electromagnetic behavior of the structures. It will be also shown that under low or moderate coupling, it is possible to describe the structures by means of a simplified model with modified parameters. Several prototype devices with different CSRR topologies and coupling levels have been fabricated to illustrate the phenomenology associated with these structures and the accuracy of their model descriptions. The results of this work can be of interest for the design of planar microwave circuits based on CSRR left handed lines.Ministerio de Economía y Ciencias de España-TEC2004-04249-C02-01 y TEC2004-04249-C02-02Comisión Europea (Red de Excelencia)-E 500252-2 METAMORPHOS

The planetary nebula IC 4776 and its post-common-envelope binary central star

We present a detailed analysis of IC 4776, a planetary nebula displaying a morphology believed to be typical of central star binarity. The nebula is shown to comprise a compact hourglass-shaped central region and a pair of precessing jet-like structures. Time-resolved spectroscopy of its central star reveals periodic radial velocity variability consistent with a binary system. While the data are insufficient to accurately determine the parameters of the binary, the most likely solutions indicate that the secondary is probably a low-mass main sequence star. An empirical analysis of the chemical abundances in IC 4776 indicates that the common-envelope phase may have cut short the AGB evolution of the progenitor. Abundances calculated from recombination lines are found to be discrepant by a factor of approximately two relative to those calculated using collisionally excited lines, suggesting a possible correlation between low abundance discrepancy factors and intermediate-period post-common-envelope central stars and/or Wolf-Rayet central stars. The detection of a radial velocity variability associated with binarity in the central star of IC 4776 may be indicative of a significant population of (intermediate-period) post-common-envelope binary central stars which would be undetected by classic photometric monitoring techniques.Comment: Accepted for publication in MNRA

Saturday night purpura: An uncommon presentation of exercise-induced vasculitis

Exercise-induced vasculitis (EIV) is a benign cutaneous vasculitis that affects healthy individuals. We report a case of EIV in a 15-year-old male patient with a striking clinical appearance triggered by a combination of prolonged standing and disco dancing in a warm environment. Pediatric dermatologists should be aware of this activity as a possible trigger of EIV, especially in teenagers

Bullous pemphigoid and dipeptidyl peptidase-4 inhibitors: The importance of the pharmacotherapeutic history

A 97-year-old man with a history of type II diabetes mellitus was treated with oral antidiabetic agents. He went to the emergency department after the appearance of blister-like itchy lesions on the abdomen and extremities since 2 months. The examination revealed eczematous lesions on the back, abdomen and extremities along with tense blisters on an erythematous base and serous content (figure 1A). In the blood test carried out, 285?mg/dL glucose and 7.1% eosinophilia stood out, with no associated leucocytosis or other relevant findings. Positive glycosuria (+++) was observed in urinalysis without other alterations. A skin biopsy was performed for histological and immunofluorescence studies that confirmed the diagnosis of bullous pemphigoid (figure 1B–D). Given the poor control of autoimmune blistering disease, possible triggers were looked for and linagliptin intake could be associated with the appearance of skin lesions 1?month earlier. ..

Corporate social responsibility and workplace health promotion: A systematic review

The complex situation that global society is facing as a result of COVID-19 has highlighted the importance of companies committing to the principles of social responsibility. Among the internal initiatives, those related to the health of workers are, obviously, highly topical. The objective of our research is to provide concise knowledge of the relationship between workplace health promotion (WHP) and corporate social responsibility (CSR) so that the relevant specialized research was gathered in a single document that lays the foundations of its applicability. A systematic review, following the PRISMA method, has been carried out. Twenty-seven articles have been selected from the main scientific databases. Their qualitative analysis concludes that CSR and WHP are linked, have beneficial reciprocal effects, need committed leadership respectful of autonomy and voluntariness, and require the establishment of specific goals within the framework of the organizations' sustainability policies. Future studies should establish the impact of the pandemic on these aspects

Anderson localization in a periodic photonic lattice with a disordered boundary

We investigate experimentally the light evolution inside a two-dimensional finite periodic array of weakly- coupled optical waveguides with a disordered boundary. For a completely localized initial condition away from the surface, we find that the disordered boundary induces an asymptotic localization in the bulk, centered around the initial position of the input beam.Comment: 3 pages, 4 figure

Reflection and transmission of waves in surface-disordered waveguides

The reflection and transmission amplitudes of waves in disordered multimode waveguides are studied by means of numerical simulations based on the invariant embedding equations. In particular, we analyze the influence of surface-type disorder on the behavior of the ensemble average and fluctuations of the reflection and transmission coefficients, reflectance, transmittance, and conductance. Our results show anomalous effects stemming from the combination of mode dispersion and rough surface scattering: For a given waveguide length, the larger the mode transverse momentum is, the more strongly is the mode scattered. These effects manifest themselves in the mode selectivity of the transmission coefficients, anomalous backscattering enhancement, and speckle pattern both in reflection and transmission, reflectance and transmittance, and also in the conductance and its universal fluctuations. It is shown that, in contrast to volume impurities, surface scattering in quasi-one-dimensional structures (waveguides) gives rise to the coexistence of the ballistic, diffusive, and localized regimes within the same sample.Comment: LaTeX (REVTeX), 12 pages with 14 EPS figures (epsf macro), minor change