Closest Approach Research Articles

FUV Observations of the Inner Coma of 46P/Wirtanen

Abstract Far-ultraviolet observations of comets yield information about the energetic processes that dissociate the sublimated gases from their primitive surfaces. Understanding which emission processes are dominant, their effects on the observed cometary spectrum, and how to properly invert the spectrum back to the composition of the presumably pristine surface ices of a comet nuclei are all critical components for proper interpretation and analysis of comets. The close approach of comet 46P/Wirtanen in 2018–2019 provided a unique opportunity to study the innermost parts of a cometary coma with the Hubble Space Telescope Cosmic Origins Spectrograph, rarely accessible with remote observations, at length scales (hundreds of kilometers) and wavelengths (900–1430 Å) previously probed only by the European Space Agency’s Rosetta spacecraft. Our observations show a complex picture for the inner coma; atomic production rates for H and O that show water is the dominant source of both, an abundance of atomic sulfur that is difficult to explain with the lifetimes of common sulfur parent molecules, and a density distribution that is poorly fit with both Haser and vectorial models.

Roll Calibration for CryoSat-2: A Comprehensive Approach

CryoSat-2 is the first satellite mission carrying a high pulse repetition frequency radar altimeter with interferometric capability on board. Across track interferometry allows the angle to the point of closest approach to be determined by combining echoes received by two antennas and knowledge of their orientation. Accurate information of the platform mispointing angles, in particular of the roll, is crucial to determine the angle of arrival in the across-track direction with sufficient accuracy. As a consequence, different methods were designed in the CryoSat-2 calibration plan in order to estimate interferometer performance along with the mission and to assess the roll’s contribution to the accuracy of the angle of arrival. In this paper, we present the comprehensive approach used in the CryoSat-2 Mission to calibrate the roll mispointing angle, combining analysis from external calibration of both man-made targets, i.e., transponder and natural targets. The roll calibration approach for CryoSat-2 is proven to guarantee that the interferometric measurements are exceeding the expected performance.

Effects of Vessel Distance and Sex on the Behavior of Endangered Killer Whales

Accurate knowledge of behavior is necessary to effectively manage the effects of human activities on wildlife, including vessel-based whale-watching. Yet, the wholly aquatic nature of cetaceans makes understanding their basic behavioral ecology quite challenging. An endangered population of killer whales faces several identified threats including prey availability and disturbance from vessels and sound. We used bio-logging tags that were temporally attached to individuals of the endangered Southern Resident killer whale population to more fully understand their subsurface behavior and to investigate vessel effects on behavior, including foraging behavior involving prey capture. We collected tag data over three field seasons in the waters surrounding the San Juan Islands, WA, United States, corresponding to the core summer area of the critical habitat of the population. Here, we used hidden Markov models to identify latent behavioral states that include characterization of different foraging states from sound and movement variables recorded by the multi-sensor tags. We tested a number of vessel variables (e.g., vessel counts, distance, and speed) on state transition probabilities, state occurrence and time spent within each behavioral state. Whales made fewer dives involving prey capture and spent less time in these dives when vessels had an average distance less than 400 yd (366 m). Additionally, we found both a sex and vessel distance effect on the state transition probabilities, suggesting that females and males respond differently to nearby vessels. Specifically, females were more likely to transition to a non-foraging state when vessels had an average distance less than 400 yd (366 m). A female’s decision to forego foraging states due to the close proximity of vessels could have cascading effects on the ability to meet energetic requirements to support reproductive efforts. This is particularly concerning in an endangered population that is in decline. Our findings, suggesting that female killer whales are at greater risk to close approaches by vessels, highlight the importance of understanding sex-specific responses to disturbance. These findings can inform future management decisions seeking to preserve foraging opportunities and enhance recovery efforts relevant to many cetacean species, including vulnerable and endangered populations.

Thermally altered subsurface material of asteroid (162173) Ryugu

Analyses of meteorites and theoretical models indicate that some carbonaceous near-Earth asteroids may have been thermally altered due to radiative heating during close approaches to the Sun1–3. However, the lack of direct measurements on the subsurface doesn’t allow us to distinguish thermal alteration due to radiative heating from parent-body processes. In April 2019, the Hayabusa2 mission successfully completed an artificial impact experiment on the carbonaceous near-Earth asteroid (162173) Ryugu4,5, which provided an opportunity to investigate exposed subsurface material and test potential effects of radiative heating. Here we report observations of Ryugu’s subsurface material by the Near-Infrared Spectrometer (NIRS3) on the Hayabusa2 spacecraft. Reflectance spectra of excavated material exhibit a hydroxyl (OH) absorption feature that is slightly stronger and peak-shifted compared with that observed for the surface, indicating that space weathering and/or radiative heating have caused subtle spectral changes in the uppermost surface. The strength and shape of the OH feature suggests that the subsurface material experienced heating above 300 °C, similar to the surface. In contrast, thermophysical modelling indicates that radiative heating cannot increase the temperature above 200 °C at the estimated excavation depth of 1 m, even at the smallest heliocentric distance possible for Ryugu. This supports the hypothesis that primary thermal alteration occurred on Ryugu’s parent body. Hayabusa2 created an artificial crater on Ryugu to analyse the subsurficial material of the asteroid. Results show that the subsurface is more hydrated than the surface. It experienced alteration processes that can be traced back to Ryugu’s parent body.

Does the fir-radio correlation evolve with redshift in irregular and disk galaxies?

It was confirmed that there is a strong linear correlation between the thermal far-infrared (FIR) and non-thermal radio emission of the star-forming galaxies. Recent works based on this correlation over large redshifts have shown that the correlation is evolving towards higher redshifts. In this paper, possible physical causes that lead to the evolution of this correlation are explored. One possible cause is that the interaction between galaxies is responsible for this behavior. We used the morphology of galaxies, as an indicator of past or present interactions, because it is generally known that the irregular morphology of galaxies is a consequence of collisions or close approaches. To test this hypothesis, a sample of dusty star-forming galaxies up to a redshift z = 3:5 from the COSMOS field has been selected. The sample has been divided, according to the morphological type, into two subsamples (disk and irregular galaxies), and the evolution of the correlation with redshift has been analyzed separately for both of them. It was found that in both subsamples there is no indication for the redshift evolution of the FIR-radio correlation. However, it was also found that the mean correlation parameter, qFIR, is lower in irregular galaxies, which may indicate that they can still affect the evolution of the correlation if their abundance in the sample increases towards higher redshifts. Disk galaxies, which statistically dominate the sample, may be responsible for the lack of this evolution. On the other hand, a fundamental problem with optically determined morphology is the dust obscuration in massive galaxies at z > 2. To test the idea that interacting galaxies are responsible for redshift evolution of the FIR-radio correlation, it is, necessary to analyze a much larger sample for which the morphology has been determined, taking into account the VLA and ALMA imaging in addition to optical images, and which contains a higher fraction of irregular galaxies. Finally, it was also found that the qFIR parameter and its evolution are very sensitive to the radio spectral index above z > 1 and that its misinterpretation and taking a constant value of ? = 0:7 may be responsible for the observed evolution of the correlation.

FREEDOM AS THE MAIN PROBLEM OF PHILOSOPHY GÜNTHER NEUMANN DER FREIHEITSBEGRIFF BEI GOTTFRIED WILHELM LEIBNIZ UND MARTIN HEIDEGGER. PHILOSOPHISCHE SCHRIFTEN, BAND 9. Berlin: Duncker & Humblot, 2019 ISBN 978-3-428-15537-8 HEIDEGGER UND LEIBNIZ. MIT EINEM GELEITWORT VON FRIEDRICH-WILHELM VON HERRMANN (DAS DENKEN MARTIN HEIDEGGERS II 2 HRSG. VON HANS-CHRISTIAN GÜNTHER). Traugott Bautz Verlag, Nordhausen, 2020 ISBN 978-3-95948-493-0

Book review focuses on two books by Gunther Neumann, dedicated to the thought of Heidegger and Leibniz. If one of the books deals specifically with the understanding of freedom in both of the two philosophers, then the other one deals more with Heidegger’s three approaches to Leibniz’s thought: (1) Interpretation of Leibniz in the context of the making of fundamental ontology and in Being and Time, as well as the reading of Leibniz after Being and Time; (2) Interpretation of Leibniz during the transition to Ereignis thought; (3) Interpetation of Leibniz in the framework of Ereignis thought. Author’s scrupulous close reading approach allows to show the changes in Heidegger’s approach to Leibniz’s philosophy, as well as sketch out the placement of Leibniz’s great themes on the horizon of Heidegger’s history of the truth of being. Author also shows that from metaphysics there stems a certain view in the modern philosophical discussions oriented on neurosciences—a certain view on the human being and on the freedom of will. On this background Heidegger appears as a thinker who has looked beyond the alloy of metaphysics and sciences, in which the concept of freedom has been greatly restricted. Heidegger manages (thanks to the radical questioning of Being) to turn the view on the problem of freedom, which appears in G. Neumann’s books as the main problem of philosophy—through the contact of Leibniz’s thought and Heidegger’s.

Integrated Community Onsite Sanitation System for Close Loop Faecal Management

The achievement of safe sanitation access is about 7.42 % in 2018, that indicates high risk of faecal contamination from unmanaged onsite sanitation system and has not been fully supported by faecal sludge service. This paper described the study of characteristic of onsite sanitation and faecal sludge for review potential of integrating of sludge handling with improved communal wastewater treatment. Faecal sludge quality were observed from pit latrines and communal septic tank, then analysis method apply cluster analysis and through close loop approach consider treatment and disposal for resource recovery. The pilot model of combined treatment of wastewater and faecal sludge was developed by anaerobic digester with a maximum 5% sludge loading, then further treatment by biofilter system and sludge drying bed. The quality of treated water can meet COD and nitrogen as effluent standard, biosolid reached a stabilization index of 40 - 60%, water content of 50-60% and less Coliform bacteria content. The characteristics of faecal sludge strength to be handled will be influenced bytechnical aspect or environment. The integrated system could be applied to manage wastewater and faecal sludge and its by products, mainly for rural area has not been catered by faecal sludge service.

Comparison of effect of aquatic interventions on cardiac modulation of obese young males in motion. A crossover trial

Abstract Study aim: The study aimed to compare the effects of passive Watsu therapy and immersion on cardiac locomotor synchronization of obese young males. Material and methods: Twenty-six volunteer obese males participated in this study (age 18.3 ± 0.32, BMI 36.9 ± 6.52). Heart rate variability parameters were recorded in different positions by the Polar H7 heart rate sensor and HRV+ software. Participants were assigned to two groups, randomly, in a single-blinded crossover design. Kubios HRV 2.2 and MATLAB were used to analyze the bio-signals. Statistical analysis was performed via t-test and ANOVA (analysis of variance) using SPSS. For the significance in results and group comparison, the paired t-test and the independent t-test were used respectively. Results: Combined results indicated that Watsu therapy increased 3 HRV vertical position parameters and immersion increased 3 HRV non-locomotor parameters, significantly (p < 0.05). Conclusion: The findings show that Watsu and immersion improved the specific autonomic cardiac modulation. However, non-contact immersion seemed to provide better synchronization of cardiac control and locomotion. The close contact Watsu approach provided improvements in autonomic cardiac regulation. Collectively, these improvements suggest the combination of both therapies in maximizing the cardiac benefits sought by aquatic therapy programs.

Homosexuality and Liminality in Sodom: The Quests for Home, Fun and Justice (Gen 19:1-29)

This essay explores the first segment of the Lot sub-narrative of the Abraham cycle (Gen 11:27–25:10). The study adopts a narrative close reading approach and canonical theological hermeneutical framework in its reading strategies (with the canon’s reception history undergirding its plausibility structures), aiming ultimately at unfolding the world of possibilities of being-in-the-world in the text, particularly from an ethical standpoint. The study shows Lot, enmeshed in his sense of marginality from YHWH’s repeated covenantal promises of progeny to Abraham, ditch time-tested tradition and embark on a quest for freedom and a home of his own, consequently, assuming significance and security in Sodom (where he sat on the city council at the gate). His initial assumed marginality in Abraham’s home attains reality in Sodom, where the Sodomites desirous of ‘having fun’ with Lot’s angelic guests (who were on a search for justice) reprimands Lot, a mere immigrant—in their view—for his audacity to rebuke them. The visitation of YHWH’s justice on Sodom renders the self-serving Lot homeless, driving him to ultimate marginality, as he inhabits the liminal space of an incestuous cave dweller. A theologico-ethical appropriation of the narrative draws attention, first, to the temptation often to be so caring to outsiders and yet be so unkind to those closest to us (like Lot). Second, tradition is a stabilising force in society and jettisoning it unnecessarily creates cascading disequilibria. Third, alienation from God is the grand source of all liminality. Fourth, inordinate desires lead to choices that bring about a breakdown in the social order. Fifth, like Lot, we need to catch heaven’s heartbeat for the oppressed and become voices for their justice in our time. https://doi.org/10.17159/2312–3621/2021/v34n1a6

Astrometric measurement and reduction of Pulkovo photographic observations of the main Saturnian satellites from 1972 to 2007 in the Gaia reference frame

Context. We present a remeasurement of old photographic plates, providing important raw data for dynamical studies of the Saturnian satellite system. The unprecedentedly accurate realization of the Gaia reference frame allows us to make a precise calibration of digitized astronegatives of the Saturnian satellite images. Aims. We reprocessed 357 astronegatives taken with the 26-inch refractor and the normal astrograph of the Pulkovo Observatory between 1972 and 2007 to obtain the positions of the main Saturnian moons in the second Gaia data release (Gaia DR2) system. Methods. Photographic plates were digitized with the Pulkovo Mobile Digitizing Device scanner. The New Astrometric Reduction of Old Observations digitizer at the Paris Observatory was used to calibrate the scanned images. Satellite image centering and astrometric reduction were performed. Results. In total, 6487 positions (equatorial coordinates) have been determined with an accuracy of 50 mas. This is confirmed by a comparison of our data with modern ephemerides. The verification of the results was performed using data from past close approaches by Saturnian satellites to Gaia reference stars, showing the adequacy of the current residual analysis. A joint review of the Pulkovo and the United States Naval Observatory intersatellite positions allows us to conclude about the existence of faint systematic effects in the satellite theories of motions at the 10 mas level.

Maximal Correlation Techniques in Constructing Non-Linear Econometric Models

Abstract Constructing non-linear stochastic econometric models is considered, from the point of view of revealing and proper reflecting quantitatively stochastic dependencies between input and output variables involved in the models. The dependencies are investigated by applying a corresponding measure of dependence, the maximal correlation. The approach enables one both to obtain corresponding non-linear transformations describing relationships between the input and output variables and to assure the existence of the model parameters estimates. As well, the approach provides obtaining the model identifiability conditions and quantitative description of the model non-linearity. The presentation is preceded with an analysis of a close approach available in the tutorial literature, with emphasizing certain delusions involved.

Retrospective analysis of the orbits of asteroids colliding with the Earth

In this paper, we consider the trajectories of real and model asteroids that lead to collisions with the Earth. They highlight the close approaches to the Earth that precede the impact. The presence of such approaches allows you to detect a dangerous object in advance, clarify its orbit, and also use the effect of a gravitational maneuver to economically prevent an asteroid from hitting the Earth. The article considers various families of collision trajectories: possible trajectories of real dangerous asteroids, as well as model ones trajectories that are not linked to a specific object. It is shown that in the first case, the approaches preceding the collision are noticeably greater.

Methods and algorithms for classifying air targets by importance based on data from an airborne radar system Part 1. Two-stage ranking of air targets according to the degree of danger during the operation of radar in the multipurpose tracking mode

Classification of air targets by rank of importance is the basis for ensuring situational awareness of pilots (crew members) of military aircraft, therefore, the problem of increasing the reliability of target classification is very urgent. The requirement to provide the pilot (crew) with full situational awareness means providing him with complete and reliable information about tactical, electronic, navigation situations and the technical condition of on-board systems. It should be noted that when classifying air targets according to the rank of importance, dangerous, favorable for attack and non-dangerous targets are currently usually distinguished. Specific tasks of classifying air targets by importance rank belong to the class of object recognition tasks. In modern aviation radio-electronic complexes, the classification of air targets according to the rank of importance is usually carried out according to the data of on-board radar systems, as well as electronic intelligence systems and optoelectronic systems. It should be noted that one of the main information modes of functioning of modern and future radar systems is the multipurpose tracking mode, in which an airborne radar can simultaneously track a large number of targets in its area of responsibility. In the conduct of hostilities, ensuring one's own security is a priority task for aircraft of various purposes. In this case, the role of dangerous air targets can be not only targets belonging to the opposing side, but also their own aircraft in dangerous encounters, in which a collision can occur between them. Therefore, the problem of preventing dangerous encounters and preventing aircraft collisions with each other becomes one of the key problems in group operations of military aviation. It should be noted that by now there are various methods of assessing goals according to the degree of their danger, but there is no systematic presentation of them. An attempt is made in the article to give a systematized presentation of new methods for solving this problem, based on a two-stage decision-making on the predicted minimum distance of closest approach and the time to reach it. Based on this approach, the following are considered: the method of subjective reduction of private indicators; procedures for determining the hazard indicators of air targets in the antenna coordinate system; rules for making decisions on the degree of danger of targets, taking into account their possible maneuver; – the composition of information support for solving this problem has been determined.

Accounting and fiscal impact of the micro and small companies of Huejutla of Reyes Hidalgo

The topic "Accounting and Fiscal Impact of Micro and Small Companies of Huejutla of Reyes, Hgo, was applied for its study to the food sales sector, the objective of this research is to understand the behavior of SMEs when using an accounting and fiscal regulation, for this research the mixed method was applied, for the qualitative part it was necessary to have a closer approach with the owners. and for the quantitative part, 314 surveys were applied with the support of 33 students. INEGI 2015 mentions that there are 394 food sales businesses, among the most outstanding data we find that of the 314 companies, 300 are micro-companies, that 74% of the people have not formalized their business, in relation to the IMSS 92% do not has its company registered and 8% registered is equivalent to 69 workers, 75% express that they do not know that the deposits reflected in the financial system cause taxes, 85% do not invoice the general public. In general, the results show a profile of resistance to compliance with the provisions of art. 31 Section IV, of the Political Constitution of the United Mexican States.

Metabolic-associated fatty liver disease (MAFLD) in coeliac disease.

Coeliac disease (CD) is considered a high-risk condition for developing non-alcoholic fatty liver disease (NAFLD) and other related metabolic disorders, particularly after commencing gluten-free diet (GFD). Recently, a new concept of metabolic-associated fatty liver disease (MAFLD) has been proposed to overcome the limitations of NAFLD definition. This study aimed at exploring the prevalence of NAFLD and MAFLD in CD patients at the time of CD diagnosis and after 2years of GFD. Furthermore, we evaluated the role of PNPLA3 rs738409 in the development of NAFLD and MAFLD in the same population. We retrospectively enrolled all newly diagnosed CD patients who underwent clinical, laboratory and ultrasonography investigations both at diagnosis and after 2years of follow-up. Moreover, a PNPLA3 rs738409 genotyping assay was performed. Of 221 newly diagnosed CD patients, 65 (29.4%) presented NAFLD at CD diagnosis, while 32 (14.5%) met the criteria for MAFLD (k=0.57). There were no significant differences between NAFLD and MAFLD, except for the higher rate of insulin resistance (IR) of MAFLD patients (75% vs 33.8%, P<.001). At 2years of follow-up, 46.6% of patients developed NAFLD while 32.6% had MAFLD (k=0.71). MAFLD subjects had higher transaminases (P=.03), LDL-cholesterol (P=.04), BMI and waist circumference and higher IR than NAFLD patients. MAFLD patients showed higher non-invasive liver fibrosis scores than NAFLD subjects (APRI=1.43±0.56 vs 0.91±0.62, P<.001; NFS=-1.72±1.31 vs -2.18±1.41, P=.03; FIB-4=1.27±0.77 vs 1.04±0.74, P=.04). About PNPLA3 polymorphisms, at 2years follow-up, NAFLD subjects presented a higher rate of heterozygosis (40.8%) and homozygosis (18.4%) polymorphisms than non-NAFLD (26.3% and 7.6%, respectively, P=.03 and 0.02), while no correlation between PNPLA3 polymorphisms and MAFLD was seen. The new MAFLD definition better reflects the metabolic alterations following GFD in CD population. This new classification could be able to identify patients at higher risk of worse metabolic outcome, who need a close multidisciplinary approach for their multisystemic disease.

General relativistic effects on Hill stability of multibody systems: Stability of three-body systems containing a massive black hole

We study the effects of general relativistic gravity on the Hill stability, that is, the stability of a multi-body system against a close approach of one orbit to another, which has been hitherto studied mainly in Newtonian mechanics and applied to planetary systems. We focus in this paper on the three-body problem and extend the Newtonian analyses to the general relativistic regime in the post-Newtonian approximation. The approximate sufficient condition for the relativistic Hill stability of three-body systems is derived analytically and its validity and usefulness are confirmed numerically. In fact, relativity makes the system more unstable than Newtonian mechanics in the sense of the Hill stability as expected by our theoretical prediction. The criterion will be useful to analyze the results of large-scale N-body simulations of dense environments, in which the stability of three-body sub-systems is important.

Analytical Framework for Space Debris Collision Avoidance Maneuver Design

An analytical formulation for collision avoidance maneuvers involving a spacecraft and a space debris is presented, including solutions for the maximum deviation and minimum collision probability cases. Gauss’s planetary equations and relative motion equations are used to map maneuvers at a given time to displacements at the predicted close approach. The model is then extended to map changes in state between two times, allowing one to propagate covariance matrices. The analytical formulation reduces the optimization problem to an eigenproblem, for both maximum deviation and minimum collision probability. Two maximum deviation cases, total deviation and impact parameter, are compared for a large set of spacecraft–debris conjunction geometries derived from European Space Agency’s Meteoroid and Space Debris Terrestrial Environment Reference (MASTER-2009) model. Moreover, the maximum impact parameter and minimum collision probability maneuvers are compared assuming covariances known at the maneuver time, to evaluate the net effect of lead time in collision probability. In all cases, solutions are analyzed in the b-plane to leverage its natural separation of phasing and geometry change effects. Both uncertainties and maximum deviation grow along the time axis for long lead times, limiting the reduction in collision probability.

Structural Deformation to β‐Cyclodextrin Due to Strong π‐Stacking in the Self‐Assembly of Inclusion Complex

AbstractWe report severe distortion to the structure of β‐cyclodextrin and partial de‐encapsulation of included guest prompted by strong π‐stacking of appended pyrene moieties in the self‐assembly of inclusion complex into toroidal nanostructures. The inclusion complex formed from bis(β‐cyclodextrin)‐substituted pyrene and bis(adamantane)‐substituted methyl viologen assembled into ring‐like structures. The rings undergo further self‐assembly which involve strong face‐to‐face π‐stacking of pyrene chromophores. Close approach of the pyrenes for π‐stacking demands severe distortion of the cyclodextrin truncated cone structure and partial de‐encapsulation of the guest from the cavity. The understanding that β‐CD can be distorted severely during self‐assembly may be helpful in the design of molecular architectures.

Bistatic radar observations of near-earth asteroid (163899) 2003 SD220 from the southern hemisphere

We report results of Canberra-ATCA Doppler-only continuous wave (CW) radar observations of near-Earth asteroid (163899) 2003 SD220 at a receiving frequency of 7159 MHz (4.19 cm) on 2018 December 20, 21, and 22 during its close approach within 0.019 au (7.4 lunar distances). Echo power spectra provide evidence that the shape is significantly elongated, asymmetric, and has at least one relatively large concavity. An average spectrum per track yields an OC (opposite sense of circular polarization) radar cross section of 0.39, 0.27, and 0.25 km2, respectively, with an uncertainty of 35%. Variations by roughly a factor of two in the limb-to-limb bandwidth over the three days indicate rotation of an elongated object. We obtain a circular polarization ratio of 0.21 ± 0.07 that is consistent with, but somewhat lower than, the average among other S-class near-Earth asteroids observed by radar.

Drop squeezing between arbitrary smooth obstacles

Abstract