Abstract
In this paper, a method based on the usage of a smartphone
for measuring simultaneously both heartbeat intervals and
respiratory intervals is presented. In particular, the commodity
...accelerometer of a smartphone is used for measuring the
seismocardiographic signal generated by heart activity and the
acceleration due to breathing movements. The measurement is
performed with the subject laying down, placing the smartphone on
his/her xiphoid process. Signal processing algorithms are presented
in the paper that can produce an accurate estimation of heartbeat
and respiratory intervals from the measured acceleration signals. A
metrological validation of the heartbeat and respiratory intervals
estimates obtained with the proposed method is carried out by
comparison with measurements obtained using an electrocardiograph
and a spirometer. Two practical examples of applications of the
measured quantities are finally reported, that are the measurement
of the Heart Rate Variability from heartbeat intervals and of the
Respiratory Sinus Arrhythmia from both the heartbeat intervals and
the respiratory signal.
The amount of ultraviolet irradiation and ablation experienced by a planet depends strongly on the temperature of its host star. Of the thousands of extrasolar planets now known, only six have been ...found that transit hot, A-type stars (with temperatures of 7,300-10,000 kelvin), and no planets are known to transit the even hotter B-type stars. For example, WASP-33 is an A-type star with a temperature of about 7,430 kelvin, which hosts the hottest known transiting planet, WASP-33b (ref. 1); the planet is itself as hot as a red dwarf star of type M (ref. 2). WASP-33b displays a large heat differential between its dayside and nightside, and is highly inflated-traits that have been linked to high insolation. However, even at the temperature of its dayside, its atmosphere probably resembles the molecule-dominated atmospheres of other planets and, given the level of ultraviolet irradiation it experiences, its atmosphere is unlikely to be substantially ablated over the lifetime of its star. Here we report observations of the bright star HD 195689 (also known as KELT-9), which reveal a close-in (orbital period of about 1.48 days) transiting giant planet, KELT-9b. At approximately 10,170 kelvin, the host star is at the dividing line between stars of type A and B, and we measure the dayside temperature of KELT-9b to be about 4,600 kelvin. This is as hot as stars of stellar type K4 (ref. 5). The molecules in K stars are entirely dissociated, and so the primary sources of opacity in the dayside atmosphere of KELT-9b are probably atomic metals. Furthermore, KELT-9b receives 700 times more extreme-ultraviolet radiation (that is, with wavelengths shorter than 91.2 nanometres) than WASP-33b, leading to a predicted range of mass-loss rates that could leave the planet largely stripped of its envelope during the main-sequence lifetime of the host star.
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IJS, KISLJ, NUK, SBMB, UL, UM, UPUK
When the panels in a photovoltaic (PV) array are subjected to a nonuniform irradiance level, some bypass diodes may turn on, and the overall power production might be affected significantly. An ...increase of the power delivered by the whole array might be obtained by means of its electrical reconfiguration, that is, the change of the series-parallel connection among the panels of which it is made up. The computation of the electrical connection among the panels that ensures the maximum delivered power is a combinatorial problem requiring powerful optimization methods. This paper is devoted to the formulation of an optimization procedure for determining the best electrical configuration among the panels. The proposed algorithm requires simple mathematical calculations, and it uses a vectorized structure; thus, it is suitable to be implemented in any embedded system for the purpose of a real-time PV array reconfiguration. The algorithm is first explained by using a pilot example, and afterward, its performance is shown by applying it to a real domestic PV field. The results show that the optimization algorithm computes an optimized configuration with a low computational burden.
•The method allows to estimate in a fast way the MPPs in a mismatched PV string.•The method uses a linear approximation of the panel's current vs. voltage curve.•The approximation method is ...generalized by an explicit matrix formulation.•The proposed method is suitable to be implemented in any programming language.
The power vs. voltage curve of a photovoltaic string operating under mismatched conditions can exhibit more than one maximum power point (MPP). In this paper, a direct method for the estimation of these points using explicit equations is introduced. The method employs a piecewise linear approximation of the current vs. voltage curve of each photovoltaic panel in the string and assumes that the open circuit voltage and the position of the maximum power points of each panel are known. Numerical results comparing the performances of the proposed approach with those offered by the adoption of the accurate single diode model show that the computational burden is reduced by almost four orders of magnitude. The approach is validated by experimental results exhibiting estimation errors lower than 5%. The satisfactory trade-off between accuracy and computation time provided by the proposed method is illustrated using two application examples: reconfiguration and long-term power production of PV strings. Moreover, an in-depth comparison of the existing simplified methods to estimate the MPPs has been performed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
A photovoltaic field is classically made of parallel connected strings, each one formed by a number of series connected modules. The total cross tied interconnection, which adds string-to-string ...wires, allows to increase the harvested energy when non-uniform operating conditions, like partial shadowing, occur. The simulation of mismatched total cross tied photovoltaic fields is mandatory to predict the increase of the power production accurately and for designing the proper power processing stage for the maximum power point tracking function. A fast and accurate simulation is also useful for model-based diagnostic purposes. In this paper an effective simulation model, which profits from a peculiar sparsity pattern of the system of non linear equations for achieving a very short computation time, is presented. It can be implemented in any platform and it has high potentialities also to be ported on embedded systems for real time simulation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The Kilodegree Extremely Little Telescope (KELT) project has been conducting a photometric survey of transiting planets orbiting bright stars for over 10 years. The KELT images have a pixel scale of ...∼23″ pixel−1-very similar to that of NASA's Transiting Exoplanet Survey Satellite (TESS)-as well as a large point-spread function, and the KELT reduction pipeline uses a weighted photometric aperture with radius 3′. At this angular scale, multiple stars are typically blended in the photometric apertures. In order to identify false positives and confirm transiting exoplanets, we have assembled a follow-up network (KELT-FUN) to conduct imaging with spatial resolution, cadence, and photometric precision higher than the KELT telescopes, as well as spectroscopic observations of the candidate host stars. The KELT-FUN team has followed-up over 1600 planet candidates since 2011, resulting in more than 20 planet discoveries. Excluding ∼450 false alarms of non-astrophysical origin (i.e., instrumental noise or systematics), we present an all-sky catalog of the 1128 bright stars (6 < V < 13) that show transit-like features in the KELT light curves, but which were subsequently determined to be astrophysical false positives (FPs) after photometric and/or spectroscopic follow-up observations. The KELT-FUN team continues to pursue KELT and other planet candidates and will eventually follow up certain classes of TESS candidates. The KELT FP catalog will help minimize the duplication of follow-up observations by current and future transit surveys such as TESS.
We present the discovery of KELT-21b, a hot Jupiter transiting the V = 10.5 A8V star HD 332124. The planet has an orbital period of P = 3.6127647 0.0000033 days and a radius of . We set an upper ...limit on the planetary mass of at confidence. We confirmed the planetary nature of the transiting companion using this mass limit and Doppler tomographic observations to verify that the companion transits HD 332124. These data also demonstrate that the planetary orbit is well-aligned with the stellar spin, with a sky-projected spin-orbit misalignment of . The star has K, , , and km s−1, the highest projected rotation velocity of any star known to host a transiting hot Jupiter. The star also appears to be somewhat metal poor and -enhanced, with and /Fe = 0.145 0.053; these abundances are unusual, but not extraordinary, for a young star with thin-disk kinematics like KELT-21. High-resolution imaging observations revealed the presence of a pair of stellar companions to KELT-21, located at a separation of 1 2 and with a combined contrast of with respect to the primary. Although these companions are most likely physically associated with KELT-21, we cannot confirm this with our current data. If associated, the candidate companions KELT-21 B and C would each have masses of ∼0.12 , a projected mutual separation of ∼20 au, and a projected separation of ∼500 au from KELT-21. KELT-21b may be one of only a handful of known transiting planets in hierarchical triple stellar systems.
This book analyzes recent labor market trends in Latin American countries and the factors that underlie the failure to create moreand more productive and rewardingjobs, a failure with substantial ...political and social costs. The authors analyze how growth and job creation in the region's economies compare with other emerging countries, the impact of job creation and destruction on productivity growth and the creation of "good" jobs, and the relative importance and role of labor market policies in improving labor market outcomes in the region.
The objective of the current study was to quantify the degree of white matter (WM) abnormalities in chronic and virally suppressed HIV-infected (HIV+) persons while carefully taking into account ...demographic and disease factors. Diffusion tensor imaging (DTI) was conducted in 40 HIV− and 82 HIV+ men with comparable demographics and life style factors. The HIV+ sample was clinically stable with successful viral control. Diffusion was measured across 32 non-colinear directions with a
b
-value of 1000 s/mm
2
; fractional anisotropy (FA) and mean diffusivity (MD) maps were quantified with Itrack IDL. Using the ENIGMA DTI protocol, FA and MD values were extracted for each participant and in 11 skeleton regions of interest (SROI) from standard labels in the JHU ICBM-81 atlas covering major striato-frontal and parietal tracks. We found no major differences in FA and MD values across the 11 SROI between study groups. Within the HIV+ sample, we found that a higher CNS penetrating antiretroviral treatment, higher current CD4+ T cell count, and immune recovery from the nadir CD4+ T cell count were associated with increased FA and decreased MD (
p
< 0.05–0.006), while HIV duration, symptomatic, and asymptomatic cognitive impairment were associated with decreased FA and increased MD (
p
< 0.01–0.004). Stability of HIV treatment and antiretroviral CNS penetration efficiency in addition to current and historical immune recovery were related to higher FA and lower MD (
p
= 0.04–
p
< 0.01). In conclusion, WM DTI measures are near normal except for patients with neurocognitive impairment and longer HIV disease duration.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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