Miracle-dz/UniFAR-FTUs huggingface dataset:
Temporal development of the magnetic zenith effect

[1] An experimental investigation of the temporal dynamics of the magnetic zenith (MZ) effect associated with ionospheric modification by high-power HF electromagnetic waves is presented. The observed electron temperature enhancement when the heater beam and the UHF radar are directed along the magnetic zenith is at least twice that observed when the heater and radar are both directed vertically. It is shown that the temperature enhancement reaches the stationary state within 10 s after the heater is turned on. Such times (∼5–10 s) are typical for the development of striations with transverse sizes of the order of several meters. Also, the temporal behavior of the ion line spectra is analyzed for the field-aligned and vertical directions of the UHF radar. A new theoretical explanation is suggested for the aspect sensitivity of the electron temperature enhancement that explains the fast manifestation of the MZ effect. Furthermore, it is shown that maximum electron heating is achieved at some intermediate inclination angle of the heater beam between the MZ and the Spitze angle. An estimate of the angle within which the maximum heating effect exists is presented.
A technique for handling multiscale electromagnetic problems using the finite difference time domain (FDTD) algorithm

With advances in system integration and packaging, the capabilities of hand-held devices and embedded bio-sensors have grown to a phenomenal scale. This in turn has led to a constant interaction between human beings and ambient electromagnetic waves. Hence there is a need for studying the effects of radiation on human physiology and also the performance of systems in such an environment. The system designers seek a full-wave solution of the entire system, taking into account a variety of environments in which it operates. However, attempts to do this substantially increase the complexities involved in computing full-wave solutions, especially when the problems involve multi-scale geometries with very fine features. For such problems, even the well-established numerical methods, such as the time domain technique finite difference time domain and the frequency domain techniques, e.g. the finite element method and the method of moments, are often challenged to the limits of their capabilities. In an attempt to address these challenges, we propose to handle the multiscale problems in three different ways, based on the dimension and the complexity of the fine features involved in the problem. Furthermore, we illustrate the efficacy of the above techniques via several examples, and the results obtained by the proposed techniques are compared with other existing numerical methods for the purpose of validation.
Direct diagnosis of infall in collapsing protostars – I. The theoretical identification of molecular species with broad velocity distributions

We have developed chemical models, including depletion on to grains, for the collapsing envelopes of protostars. Our primary goal has been to identify molecular species having broad velocity distributions, so that observations of their line profiles can be employed to diagnose the dynamics of protostar formation, and to yield information on the collapse age and depletion rate. Previously obtained data for NH3 emission lines, from a number of dark cores with embedded protostars, have shown no clear evidence for systematic collapse. Results from our model indicate that the collapse initiates very soon after the formation of an isothermal pressure-balanced sphere. The collapse is preceded by a period of exceptional quiescence. We demonstrate here that as depletion reduces the fractional abundance of NH3 in the accelerating gas of an infalling envelope and prevents the formation of broad wings on NH3 emission lines, the fractional abundances of some other species initially increase as the heavy elements become depleted, leading those species to have emission lines broader than those of NH3. CH is an observable species which, for a large variety of conditions, possesses a fairly constant or increasing fractional abundance in collapsing envelope gas in which depletion is occurring. High angular resolution observations of CH would be very desirable, but would require appropriate instrumentation on an array, or perhaps the Arecibo telescope. When the water abundance is sufficiently high in the outer envelope, so that many molecular ions are removed primarily in reactions with it rather than by dissociative recombination, the abundances of HCO+, N2H+ and H2S rise when collapse and depletion occur. Millimetre lines from these species can be observed with single-dish telescopes at higher angular resolution than can NH3, resulting in their lines having broader wings in spatially resolved sources than those of NH3, even when their abundances relative to NH3 do not increase substantially in the infall. HCO is a particularly interesting species, because its abundance ratio relative to HCO+ increases with growing density if the fractional abundance of gas-phase heavy metals remains constant. Also, HCO line emission can be observed with high angular resolution.
Effects of Sex on the Susceptibility for Atrial Fibrillation in Pigs with Ischemic Heart Failure

Atrial fibrillation (AF) is the most prevalent arrhythmia, often caused by myocardial ischemia/infarction (MI). Men have a 1.5× higher prevalence of AF, whereas women show a higher risk for new onset AF after MI. However, the underlying mechanisms of how sex affects AF pathophysiology are largely unknown. In 72 pigs with/without ischemic heart failure (IHF) we investigated the impact of sex on ischemia-induced proarrhythmic atrial remodeling and the susceptibility for AF. Electrocardiogram (ECG) and electrophysiological studies were conducted to assess electrical remodeling; histological analyses were performed to assess atrial fibrosis in male and female pigs. IHF pigs of both sexes showed a significantly increased vulnerability for AF, but in male pigs more and longer episodes were observed. Unchanged conduction properties but enhanced left atrial fibrosis indicated structural rather than electrical remodeling underlying AF susceptibility. Sex differences were only observed in controls with female pigs showing an increased intrinsic heart rate, a prolonged QRS interval and a prolonged sinus node recovery time. In sum, susceptibility for AF is significantly increased both in male and female pigs with ischemic heart failure. Differences between males and females are moderate, including more and longer AF episodes in male pigs and sinus node dysfunction in female pigs.
On magnetic-field-induced non-geodesic corrections to relativistic orbital and epicyclic frequencies

We discuss non-geodesic corrections to orbital and epicyclic frequencies of charged test particles orbiting a non-rotating neutron star with a dipole magnetic field. Using a fully relativistic approach we consider the influence of both the magnetic attraction and repulsion on the orbital and epicyclic motion. The magnetic repulsion introduces a rather complex and unusual behaviour of the circular orbital motion that is well defined down to the radius where the vertical epicyclic frequency loses its meaning. We demonstrate that for the intensity of the magnetic interaction appropriately restricted, the stable circular orbits extend down to the magnetic innermost stable circular orbit (MISCO) that is located well under the geodetic innermost stable circular orbit (GISCO) and even can reach the region under the photon circular orbit. The lowest stable circular orbit at rMISCOmin = 2.73M, associated with the highest possible orbital frequency , corresponds to the critical value of the particle-specific charge and the neutron star magnetic dipole moment product . For the magnetic attraction acting above the GISCO, the situation is much more simple and we demonstrate that the most significant correction arises for the radial epicyclic frequency and consequently for the location of the MISCO when the strong magnetic attraction pushes its location far behind the location of GISCO. We show that the Lorentz force also naturally violates the equality of the orbital and vertical epicyclic frequencies implied by the spherical symmetry of the background Schwarzschild geometry giving rise to the new effect of nodal precession of the orbital motion plane. Finally, we apply the magnetic attraction corrections on the relativistic precession model of the twin-peak high-frequency quasiperiodic oscillations observed in the galactic low mass x-ray binaries, showing possible high relevance of the modified radial epicyclic frequency.
A comparison of scaled Popov and maximum entropy controller synthesis for flexible structures

The scaled Popov criterion is used to derive an upper bound for the worst case /spl Hscr//sub 2/ norm over a set of linear, time-invariant, norm-bounded, block-structured parameter perturbations. This upper bound provides the basis for scaled Popov controller synthesis, which minimizes the upper bound and guarantees asymptotic stability of the closed-loop system for all real parameter perturbations in the specified set. Numerical examples demonstrate the tradeoff between achievable /spl Hscr//sub 2/ performance and guaranteed robustness to real parameter perturbations as well as the reduction in conservatism due to the scaling matrix. These results are then compared to robust controllers obtained from the maximum entropy design technique. Both approaches are shown to yield positive real controllers for colocated structures under high levels of uncertainty in the damped natural frequencies.
A new method for compensating actuator delay in real–time hybrid experiments

We developed an on–line experimental system for conducting hybrid experiments in real time. It combines a computer, which conducts vibration simulation and generates a control signal, and a hydraulic actuator, which conducts a vibration experiment driven by the control signal. This system compensates for actuator delay and thus enables experiments to be carried out in real time. We evaluated the stability of the experiments with respect to the mass of the structure under excitation, and we developed a new method for compensating actuator delay in order to increase the stability condition. In this method, the compensated control signal is generated from the simulation results by using not only displacement but also velocity and acceleration. This method provides a stability criterion (allowable ratio of mass of the structure under excitation to that of a numerical model) about three times larger than that from the current method.
Work and energy equations and the principle of generalized effective stress for unsaturated soils

The effective stress principle has been efficiently applied to saturated soils in the soil mechanics and geotechnical engineering practice; however, its applicability to unsaturated soils is still under debate. The appropriate selection of stress state variables is essential for the construction of constitutive models for unsaturated soils. Owing to the complexity of unsaturated soils, it is difficult to determine the deformation and strength behaviors of unsaturated soils uniquely with the previous single‐effective‐stress variable theory and two‐effective‐stress‐variable theory in all the situations. In this paper, based on the porous media theory, the specific expression of work is proposed, and the effective stress of unsaturated soils conjugated with the displacement of the soil skeleton is further derived. In the derived work and energy balance equations, the energy dissipation in unsaturated soils is taken into account. According to the derived work and energy balance equations, all of the three generalized stresses and the conjugated strains have effects on the deformation of unsaturated soils. For considering these effects, a principle of generalized effective stress to describe the behaviors of unsaturated soils is proposed. The proposed principle of generalized effective stress may reduce to the previous effective stress theory of single‐stress variable or the two‐stress variables under certain conditions. This principle provides a helpful reference for the development of constitutive models for unsaturated soils. Copyright © 2009 John Wiley & Sons, Ltd.
Black Holes and Magnetic Fields

The possible stationary axisymmetric electromagnetic fields in a vacuum cavity between an initially neutral black hole and a surrounding plasma shell are investigated. It is shown that such fields must be near ''uniform'' (in a sense defined in the paper) and that the flux of the magnetic field across one-half of the surface of a neutral hole (of fixed mass) decreases as the angular momentum of the hole increases. (AIP)
Aflatoxin contamination of animal feeds and its predictors among dairy farms in Northwest Ethiopia: One Health approach implications

Background In dairy farming, animal feed is the first line of food safety. Animal feed can become contaminated and spoiled on farms or in storage facilities due to the diverse microorganisms that are naturally present around or on various animal feeds. This study aims to assess the level of aflatoxin and predictors in animal feeds among dairy farms in the South Gondar Zone of Ethiopia. Methods A total of 100 samples of each animal feed ingredient (atella, hay, commercial concentrates, and cut and carry pasture) were obtained. A total of 400 animal feed ingredient samples were tested separately among 100 randomly chosen dairy farmers for aflatoxin analysis. Simultaneously, swabs from cow udders and water samples were also collected. Using a structured and pretested questionnaire, the knowledge and practices of animal feed administrators responsible for managing animal feed were also evaluated. Descriptive statistics and logistic regression models were used to identify determinants. Results From the total animal feed analyzed, 96% was positive for aflatoxins. Feed storage facilities, feed storage duration, education of animal feed administrators, mixed concentrates, and previous training were found to be associated with aflatoxin contamination levels in animal feeds. Conclusions The levels of aflatoxin contamination in animal feeds were found to be higher than the recommended limit; these findings suggest the spread of aflatoxin contamination between humans and animals. Furthermore, the occurrence of aflatoxins in the environment results from milk becoming contaminated with aflatoxins. A One Health strategy should therefore receive special consideration to tackle such problems and safeguard consumer safety.
DETERMINATION OF ANTIOXIDANT ACTIVITY, TOTAL PHENOLIC AND FLAVONOID CONTENTS OF MALAYSIAN STINGLESS BEE PROPOLIS EXTRACTS

This study aims to determine the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of ethanolic extract propolis (EEP) and water extract propolis (WEP) derived from six Malaysian stingless bee species. The TPC and TFC were measured by Folin-Ciocalteu colorimetric and aluminium chloride methods, respectively. The antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assay. The results indicated that EEP of Geniotrigona thoracica had the highest TPC and TFC at 259.84 ± 4.97 mg/g GAE and 435.00 ± 6.57 mg/g QE, respectively. Similarly, EEP of G. thoracica exhibited the greatest free radical scavenging activity with the percentage of inhibition at 88.00 ± 13.34% and IC50 of 104. 20μg/mL. Antioxidant activity was highly correlated with TPC (R2 = -0.744, p < 0.05) whereas no correlation was observed between TFC and antioxidant activity. This study indicates that the antioxidant property of the propolis extract may be influenced by elevated levels of phenolic content. In conclusion, ethanolic extract of G. thoracica is the greatest source of antioxidants among the six tested Malaysian stingless bee propolis and this suggests that the extract may serve as a promising source of antioxidant agent.
A longitudinal assessment of appetite loss and nutritional care among postoperative patients in Vietnam

Background Post-operative appetite loss is an important complication affecting surgical outcomes. It has been estimated that nearly 60% of patients having gastrointestinal or major elective surgeries suffer from malnutrition. Appetite refers to the physical desire for food appetite, and losing appetite after surgery may result in a decrease in body weight, impairment of intestinal absorption and eventually, malnutrition among postoperative patients. This study aims to assess appetite status and other relevant factors among abdominal postoperative patients in Vietnam. Methods A cross-sectional study was conducted on 169 abdominal postoperative patients from June 1st to August 30th, 2016 at Hanoi Medical University Hospital, Hanoi, Vietnam. Appetite score was computed by using the Council on Nutrition Appetite Questionnaire (CNAQ). This study used GEE to account for the potential correlation of outcomes of the longitudinal assessment, assuming an independent correlation structure. Results The primary and secondary outcome measures: highest average appetite score was recorded in the preoperative day and the score declined throughout seven-day duration. Patients who were female, under general anesthetics and being under open surgery tended to get lower appetite scores. The majority of patients had moderate to good appetite in both the preoperative day and seven days post-operation. Conclusion Women should receive more care and help in regaining their appetite after surgery. Treatment for appetite loss through non-pharmaceutical measures should be prioritized. Interventions that increase the appetite of patients after abdominal surgery should be targeted on patients being under general anesthetic as well as open surgery and be undertaken with caution.
Assessment of Physicochemical Parameters in Two Winegrapes Varieties after Foliar Application of ZnSO4 and ZnO

One-third of the world’s population is suffering from “hidden hunger” due to micronutrient deficiency. Zinc is acquired through diet, leading its deficiency to the development of disorders such as retarded growth, anorexia, infections, and hypogeusia. Accordingly, this study aimed to develop an agronomic workflow for Zn biofortification on two red winegrapes varieties (cv. Castelão and Syrah) and determine the physicochemical implications for winemaking. Both varieties produced in Setúbal (Portugal) were submitted to four foliar applications of ZnSO4 or ZnO (900 and 1350 g ha−1, respectively), during the production cycle. At harvest, Zn biofortification reached a 4.3- and 2.3-fold increase with ZnO 1350 g ha−1 in Castelão and Syrah, respectively (although, with ZnSO4 1350 g ha−1 both varieties revealed an increase in Zn concentration). On a physiological basis, lower values of NDVI were found in the biofortified grapes, although not reflected in photosynthetic parameters with cv. Syrah shows even a potential benefit with the use of Zn fertilizers. Regarding physical and chemical parameters (density, total soluble solids, dry weight, and color), relative to the control no significant changes in both varieties were observed, being suitable for winemaking. It was concluded that ZnSO4 and ZnO foliar fertilization efficiently increased Zn concentration on both varieties without a negative impact on quality, but cv. Castelão showed a better index of Zn biofortification and pointed to a potentially higher quality for winemaking.
Gas-Phase Infrared Spectrum of the Coronene Cation

The gas-phase infrared spectrum of the coronene cation in the 700-1700 cm-1 range is presented. The spectrum is obtained via multiphoton dissociation spectroscopy of ionic coronene stored in a quadrupole ion trap using the intense and narrowband infrared radiation of a free electron laser. The spectrum shows main absorption peaks at 849, 1327, and 1533 cm-1 along with some weak and barely resolved features, in good agreement with density functional calculations if the effects of vibrational anharmonicity are accounted for. Relative line intensities show remarkable differences with respect to matrix isolation data. The novel experimental technique applied here leads in a natural way to an absorption spectrum of highly excited species. Hence, measured absorption spectra can be compared rather directly to interstellar emission spectra, negating to some extent the need for detailed model calculations.
VLA H92α and H115β Recombination Line Observations of the Galactic Center H II Regions: The Sickle (G0.18–0.04) and the Pistol (G0.15–0.05)

The Very Large Array has been used in the CnB and DnC configurations to observe the remarkable Galactic center sources, the Sickle and the Pistol, near ℓ = 0. °18, b = -0. °04. These H II regions have an unusual morphology and may be physically associated with the linear nonthermal filaments at ℓ = 0. °18, which appear to intersect the sources. The H92α (8.31 GHz) and H115β (8.43 GHz) radio recombination lines arising from these sources have been observed with angular resolutions of 6'' and 9'', respectively. In addition, there is a probable detection of the helium line in the Pistol (Y+ ~ 14% ± 6%), while in the Sickle, no helium lines were detected with an upper limit of Y+ ~ 5% (3 σ). A complex velocity field has been observed in both sources. The LSR velocity in the Sickle varies from 0 to 75 km s-1, with an average velocity of ~35 km s-1; the average velocity of the Pistol is ~115 km s-1. The recombination line properties of the Sickle and the Pistol (FWHM line widths, line-to-continuum ratios, β-to-α ratio) are consistent with photoionization from hot stars. The β-to-α line ratio of ~0.35 ± 0.07 over most of the Sickle and Pistol does not differ significantly from the LTE value of 0.28. The average LTE electron temperature, T*e, for the Sickle (~5500 K) is similar to typical Galactic center H II regions, and T*e for the Pistol is somewhat lower (~3600 K). An additional H II component in the line profiles of three regions of the Sickle in which the nonthermal filaments are present suggests that an interaction between the ionized gas and the nonthermal filaments is occurring. The probable detection of He92α in the Pistol and the nondetection in the Sickle may be due to a difference in the radiation field of the ionizing sources.