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Introducción: El registro ARGEN-IC permitió conocer las características clínicas y epidemiológicas de la insuficiencia cardíaca aguda (ICA) en nuestro país; sin embargo, no contamos con datos nacionales de las consecuencias sobre la ICA de la implementación del distanciamiento social, preventivo y obligatorio a causa de la pandemia por SARS-CoV-2. Objetivo: Evaluar las características clínicas y epidemiológicas de los pacientes ingresados al registro ARGEN-IC durante el confinamiento y distanciamiento social debido a la pandemia por SARS-CoV-2. Materiales y métodos: Se compararon pacientes (p) incorporados al registro ARGEN-IC durante marzo-junio de 2019 (grupo A: Era No COVID) con los ingresados en igual período de 2020 (grupo B: Era COVID). Se registraron los datos de filiación, las características clínicas, bioquímicas, imagenológicas y terapéuticas durante la hospitalización y las respectivas complicaciones (mortalidad cardiovascular y no cardiovascular). Resultados: Se incluyeron 361 p, 222 en el grupo A y 139 en el grupo B. Se observaron diferencias significativas entre ambas poblaciones en cuanto a edad, grupo A 70,9 ± 14,8 años vs. grupo B 75 ± 13,3 (p = 0,008); antecedente de hipertensión arterial, grupo A 70,2% vs. grupo B 87,7% (p

Solar cells that integrate concentration photovoltaic systems are usually exposed to inhomogeneous illumination and temperature profiles which influence their performance. Under such conditions, the solar cell behavior is only accurately modeled if the diode and resistive losses are considered to be distributed across the solar cell instead of being gathered, as in the conventional lumped model. This paper presents a distributed diode model and its experimental validation, which was carried out for standard test conditions and a range of temperature and concentration levels going from 25 to 70 °C and 1 to 30 suns, respectively, for both homogeneous and a set of inhomogeneous profiles. Modeled and experimental results showed good agreement, thus validating the model. The results of traditional and distributed model approaches are compared with homogeneous and inhomogeneous profiles of irradiation and temperature. Finally, we analyze the effect of different profiles on cell performance.

A theoretical model has been developed to describe the response of V-trough systems in terms of module temperature, power output and energy yield using as inputs the atmospheric conditions. The model was adjusted to DoubleSun s concentration technology, which integrates dual-axis tracker and conventional mono-crystalline Si modules. The good agreement between model predictions and the results obtained at WS Energia laboratory, Portugal, validated the model. It is shown that DoubleSun s technology increases up to 86% the yearly energy yield of conventional modules relative to a fixed flatplate system. The model was also used to perform a sensitivity analysis, in order to highlight the relevance of the leading working parameters (such as irradiance) in system performance (energy yield and module temperature). Model results show that the operation module temperature is always below the maximum working temperature defined by the module manufacturers.

In an earlier paper we discussed the role of thermionic emission in the production of electrons by a micrometeoroid entering the earth's night-side atmosphere. There we confined our attention to fast moving micrometeoroids entering the earth's atmosphere, normally. Here we extend that work to include both faster and slower moving micrometeoroids of low work function entering the earth's atmosphere at several discrete angles. We have also removed several simplifying assumptions from the earlier analysis and also included a new current (which we call the ablation current), which plays a progressively important role in calculating the grain charge with increasing entry speed. As before the present study shows how thermionic emission extends the altitude range of electron emission, with the initial angle of entry playing a crucial role. Even more important is the role of initial entry speed which changes the altitude profile of electron emission not only quantitatively but also qualitatively which provides a clear discriminant between these two classes of micrometeoroids that are designated by their entry speed. Limitations of the present study and proposed future extensions are discussed.

Strong kinetic heating of grains is frequently associated with a melting transition in plasma crystals. At high pressures, above 100 mTorr, the melting transition is preceded by a vibrational phase whereas at low pressures, below 50 mTorr, observed large amplitude self-excited oscillations can lead to lattice disruption. At such low background gas pressures, only single layer crystals are formed. This work focuses on the low pressure regime and provides a theory of the self-excited oscillations which explains both the pressure and the power dependence of these oscillations as well as their threshold behavior. The implications for the melting transition are pointed out.

It is shown that the resonant streaming energy associated with cross-field motions (due to the cross product of dc electric and magnetic fields) of the plasma particles can be coupled to low-frequency electrostatic waves. Conditions under which unstable waves appear are obtained for both collisionless and collisional dusty magnetoplasmas. The relevance of the present investigation to understanding the origin of nonthermal fluctuations in laboratory and space plasmas is pointed out.

It is shown how a nonuniform dust density distribution modifies the dust acoustic wave (DAW) propagation in a dusty plasma. The dispersion relation for the DAW in the presence of arbitrary dust density distributions are derived and analyzed.

A large number of laboratory observations reveal the formation of ordered linear chains and sheets composed of charged dust grains levitated in the sheath region of radio-frequency or dc plasma discharges at very low pressures. At higher pressures, three-dimensional structures are typically formed. Recently, a number of low gas pressure experiments have explored the generation of large amplitude vertical oscillations by lowering either the background pressure or the plasma power below a threshold value, or by imposing an external force that arises from a low-frequency sinusoidal voltage in the sheath region. A theoretical model is presented that successfully describes the phenomenology in various experiments, including the observed self-excited oscillations, nonlinear resonance and parametric oscillations. A new forcing mechanism, namely the modulational forcing, for exciting nonlinear resonances is proposed.

We solve the simultaneous equations for continuity of charge, mass, momentum and energy of a meteoroid entering the Earth's atmosphere to study its charging, deceleration, mass loss and heating along its path. In this analysis we also include the effects of thermionic emission from the frictionally heated meteoroid, which hitherto have not been considered. We have limited our analysis to the free-molecular regime which corresponds to meteoroids of radius ⩽1 cm in our altitude range of interest (H⩾80 km ) . We have also limited our treatment to the night side of the Earth so as to avoid the complicating role of photoemission while emphasizing the role of thermionic emission. Our results show that, while the same meteoroid can change its charge polarity during flight, meteoroids with widely different material work functions could have opposite polarity at the same altitude. We find out that, while the escaping thermionic electrons do not constitute a significant source of energy loss from the surface, they could be a larger source of meteoric electrons at high altitude compared to electrons produced by the ablation process, particularly if the work function of the meteoroid is sufficiently small (i.e W⩽2 eV ). Furthermore we find that the altitude range of meteoric ionization is larger than in the case when ionization is due only to collisions between sublimating molecules and background molecules. In addition the ionization has an earlier onset and a later shut-off.

Large Amplitude Oscillations Sustained by Stochastic Plasma Density Fluctuations in Plasma Sheaths

Concentration Photovoltaic (CPV) systems usually exhibit inhomogeneous illumination profiles along their receiver and even on the cells themselves. The illumination profile that reaches the cell will set specific current distributions and temperatures on the device thus modifying its I-V curve. Such effect is weakly reproduced by the conventional lumped models which treat, jointly, all ohmic losses. In this paper we focus on the development of a model to predict the cells response under such inhomogeneous profiles by taking into account the ‘distributed diode effect’. Comparison between experimental and model results show good agreement for different temperatures and illumination profiles.

In a recent paper, Takamura et al. [Phys. Plasmas 8, 1886 (2001)] described a variety of dynamic behaviors of dust grains in a dusty plasma device under conditions of a weak friction with gas molecules, that is, at low neutral background gas pressures. When the gas pressure is decreased below a critical value, an instability leading to large amplitude dust oscillations is observed in a single horizontal layer of dust grains trapped near the plasma–sheath boundary above a negatively biased mesh electrode. The instability mechanism has been identified as delayed charging of a dust grain in a plasma sheath. Our objective here is to indicate that the delayed charging mechanism cannot account for stochastic dust oscillations, and to point out a new mechanism that can explain the observed features of large amplitude self-excited dust oscillations.

A model to determine the performance of different configurations of single axis tracking is presented. The analysis of the results shows that the output of a PV receptor mounted on an inclined axis with a north‐south direction has a high acceptance angle and features low power losses, since the misalignments are greatest when the available irradiation is lowest. These results suggest the possibility of single axis tracking for low concentration CPV systems.

Photovoltaic (PV) technology has been gaining a significant share in Portugal's renewable energy mix. In this paper we focus on the analysis of 29 PV systems (mounted and connected to the grid under the micro‐generation incentive scheme in Portugal), from which 59% are DoubleSun® technology, the remaining being flat‐plate systems. The period in analysis is July 2009–June 2010. A preliminary analysis of the PV systems has confirmed their high potential in Portugal and highlighted the relevance of such analysis to identify: (1) the geographical characterization of PV performance across mainland Portugal; (2) improvement of a tool [1] that predicts the potential of different PV technologies; and (3) the challenges of PV systems when installed on‐field and connected to the grid.

The thermal behavior of a concentration (CPV) receiver strongly influences the performance of the cells and, consequently, the whole system. In this study we validate a thermal CFD‐FEA model that is under construction to work as a driving decision tool on the development and optimization of the HSUN® receiver.

The paper presents the HSUN®, a new medium concentration photovoltaic (CPV) system, developed and produced by WS Energia S.A. The low cost manufacturing and standard components used by HSUN® technology increases the potential of the system to reach grid parity.The system was designed to have stable performance and low cost manufacturing, with a total active collector area of 1.68 m2 and 6.3 kg/m2 of weight. Based on a 20X integrated parabolic trough with coupled reflective secondary optics, the system uses high efficiency silicon cells, a passive cooling integrated system and is integrated in 1‐axis horizontal tracking structure, the WS CPV HORIZON®. The open‐chain configuration ensures that the wind drag is greatly reduced, increasing the reliability of the tracker, while the optimized optics design enables a high acceptance angle and uniform distribution of radiation throughout the PV receiver, using low‐cost and low‐weight components. Ray tracing simulations and experimental imaging acquisitions of the...

Summary form only given. The problem of the shielding potential around a body immersed in a collisionless plasma is investigated for the case of a body emitting electrons due to thermionic emission, photoemission and secondary emission. The system is investigated by means of an analytic, kinetic theory as well as particle-in-cell (PIC) simulations. The kinetic theory takes into account self-consistently plasma particles collection by the body as well as electron emission. The theory is derived under the assumption of spherical symmetry so that conservation of energy and angular momentum can be used to calculate the plasma distribution functions at any given point in phase space. Far away from the body, the plasma is assumed unperturbed and described by a Maxwellian distribution function at rest. Thus, the unperturbed plasma acts as a source of particles balancing the absorptions from the body and a steady state is eventually reached. Furthermore, the theory is formulated for positively charged bodies and for radial profiles of the shielding potential presenting an attractive well, as found with PIC simulations by Delzanno et al. for the case of thermionic emission. This assumption is needed in order to be able to describe correctly potential barriers to the particle motion. The theory is shown to be in good agreement with PIC simulations. Furthermore, several cases (focusing on parameters typical of laboratory experiments) are presented for the three different emission mechanisms, showing that shielding potentials having an attractive well are possible for all emission mechanisms. The influence of physical parameters such as ion to electron mass ratio, temperature of the emitted electrons, work function of the body, etc is also shown

Summary form only given. Powerful electric currents and transient luminous events (sprites, blue jets and gigantic jets) have been detected in discharges between thunderclouds and the lower ionosphere. The occurrence of such phenomena is strongly related to the occurrence of ultra low frequency (ULF~3-50 Hz) waves and to the occurrence of positive polarity cloud-to-ground flashes. We present a novel mechanism that shed light on the origin and propagation of the observed ULF waves. Ionospheric clouds are composed of charged ice/smoke particulates, protons, electrons and neutrals. Our objective here is to show that such partially ionized dusty plasmas with streaming electrons in ionospheric clouds may support unstable dust acoustic waves (DAWs~3-12 Hz). For our purposes, we employ a multifluid dusty plasma model and derive the dispersion relation for modified DAWs in a magnetized, collisional plasma. The dispersion relation is analyzed numerically to obtain the growth rate and threshold

The kinetic theory of collisionless electrostatic shocks resulting from the collision of plasma slabs with different temperatures and densities is presented. The theoretical results are confirmed by self-consistent particle-in-cell simulations, revealing the formation and stable propagation of electrostatic shocks with very high Mach numbers ($M \gg 10$), well above the predictions of the classical theories for electrostatic shocks., Comment: 6 pages, submitted to Phys. Rev. Lett

[1] Powerful electric currents and transient luminous events (sprites, blue jets and gigantic jets) have been detected in discharges between thunderclouds and the lower Ionosphere. The occurrence of such phenomena is strongly related to the occurrence of Ultra Low Frequency (ULF ∼ 6–50 Hz) waves and to the occurrence of positive polarity cloud-to-ground flashes. In the present letter, we present a novel mechanism to explain the origin and propagation of the observed ULF waves. Ionospheric clouds are composed of charged ice/smoke particulates, protons, electrons and neutrals. Our objective here is to show that such partially ionized dusty plasmas with streaming electrons in ionospheric clouds may support unstable ULF dust acoustic waves (DAWs). For our purposes, we employ a multifluid dusty plasma model and derive the dispersion relation for modified DAWs in a magnetized collisional plasma. The dispersion relation is analyzed numerically to obtain the growth rate and threshold.

A Comment on the Letter by T. Kaneko, H. Tsunoyama, and R. Hatakeyama, Phys. Rev. Lett. 90, 125001 (2003). The authors of the Letter offer a Reply.

0654 Electromagnetics: Plasmas; 2471 Ionosphere:Plasma waves and instabilities; 2487 Ionosphere: Wavepropagation(6934);3304MeteorologyandAtmosphericDynamics:Atmospheric electricity; 3324 Meteorology and AtmosphericDynamics: Lightning; 9900 Corrections. Citation: Sorasio, G.,P. K. Shukla, D. P. Resendes, and J. T. Mendonc¸a (2004),Correction to ‘‘Origin of ELF/ULF waves triggered by positivecloud to ground lightning above mesoscale connective systems,’’Geophys. Res. Lett., 31, L14112, doi:10.1029/2004GL020874.

[1] It is shown that charged dust grains can be accelerated by the nonuniform space charge electric fields that are created by the ponderomotive force of circularly polarized electromagnetic cyclotron waves. The relevance of our investigation to dust energization in the Earth's mesospheric plasma is stressed.

We have analyzed the dynamics of a single grain immersed in a plasma sheath, under low pressure conditions. The influence on the grain dynamics of an electrode potential modulation have been analytically and numerically explored. For the first time the effects of this excitation technique on the plasma sheath environment have been theoretically analyzed, and the grain motion resulting uom the sheath modification induced by the external driver have been studied. Comparison with experimental data inferred from published investigations is also presented.

The HiPER facility has been proposed recently to demonstrate fast ignition of laser driven inertial fusion targets. According to the present design, HiPER will have a 3ω, multi-beam, multi-ns-pulse of about 250 kJ and a 2ω or 3ω ignition beam delivering 70 kJ in about 15 ps. We present here studies on laser-driven fast-ignitor targets driven by 100-300 kJ compression pulses, followed by 70-100 kJ ignition pulses.

A kinetic theory for the equilibrium of an unmagnetized plasma consisting of electrons and ions surrounding a spherical body emitting electrons (due to thermionic emission, photoemission, or secondary emission) is presented. The theory is valid for positively charged bodies, neglects collisions of the plasma particles, and is formulated for profiles of the shielding potential presenting an attractive well. Particle-in-cell simulations are shown to be in good agreement with the theory. An approximated criterion is derived to determine the presence of the potential well.

In this article we explore theoretically the role of lightning and atmospherical discharges in destabilizing Ultra Low Frequency (ULF) waves in the Ionosphere. The idea, which could seem quite exotic, takes its origin from the experimental observation that the occurrence of Ultra Low Frequency ULF ~ 6–50 Hz) waves is strongly related to the occurrence of positive polarity cloud-to-ground flashes (+CG) The interest in the subject, on the other hand, comes from the fact that the occurrence of ULF waves is not only related to the occurrence of positive polarity flashes but also to the occurrence of newly discovered transient luminous phenomena as sprites, blue jets and gigantic jets. Sprites, as well as blue jets and gigantic jets, are luminous events which have been detected in discharges between thunderclouds (~ 10 km from Earth's surface) and the lower Ionosphere (mesosphere ~90 km) These transient luminous phenomena strongly affect the atmospheric electricity, due to transfer of large amounts of charge between different regions of the atmosphere (a gigantic jet can remove as much as 0.02% of the total atmospheric charge), and suggest that some important components of the global electric circuit have still to be identified and incorporated in the theoretical framework. Another important aspect is that, during the charge transfer process (electrical discharge), sprites, blue jets and gigantic jets modify the chemistry of a large portion of the stratosphere and mesosphere, with poorly understood influences on global climate changes. In order to survey the total rate of occurrence and the implications of such phenomena on continental and global scale one needs a signature that can be easily detected by remote measurements and independent from in situ video observations. To understand whether the ULF waves can be used as sprites signatures, we explore the relation between positive polarity lightning and ULF waves by presenting a theory which explains the origin and threshold of the observed ULF waves. As a result, we obtain that very large positive polarity flashes give rise to ULF Dust Acoustic waves in the Ionosphere. We also find that the ULF waves may be destabilized, in absence of positive polarity flashes, by mean of very large Ionosphere to thunderclouds discharges, such as gigantic blue jets, which create large dipole electric fields, comparable with the ones produced by +CG lightning.

It is shown that shear waves in a strongly coupled dusty plasma with nonuniform plasma pressure and dust density can be destabilized. The dispersion relation as well as the instability condition have been found and investigated in detail.

Recently the dynamics of dust grains trapped in the sheath region of radio-frequency (rf) or dc plasma discharges under low pressure conditions has attracted the attention of the dusty plasma community. Several experiments have been performed in order to explore the dynamics of dust grains levitating above the negatively biased electrode. Under very low pressures, several experimental groups have observed the generation of self excited large amplitude vertical oscillations which arise by lowering either the background pressure or the plasma number density. In other experiments, the vertical oscillations have been driven by an external sinusoidal voltage applied to a wire in the sheath region. A theoretical model is presented that successfully describes the phenomenology in these various experiments including the observed self excited oscillations and nonlinear resonance oscillations.