211 research outputs found
Rayleigh-Lidar Observations of Mesospheric Gravity Wave Activity above Logan, Utah
A Rayleigh-scatter lidar operated from Utah State University (41.7°N, 111.8°W) for a period spanning 11 years ― 1993 through 2004. Of the 900 nights observed, data on 150 extended to 90 km or above. They were the ones used in these studies related to atmospheric gravity waves (AGWs) between 45 and 90 km. This is the first study of AGWs with an extensive data set that spans the whole mesosphere. Using the temperature and temperature gradient profiles, we produced a climatology of the Brunt-Väisälä (buoyancy) angular frequency squared, N2 (rad/s)2. The minimum and maximum values of N2 vary between 2.2×10-4 (rad/s)2 and 9.0×10-4 (rad/s)2. The corresponding buoyancy periods vary between 7.0 and 3.5 minutes. While for long averages the atmosphere above Logan, Utah, is convectively stable, all-night and hourly profiles showed periods of convective instability (i.e., negative N2). The N2 values were often significantly different from values derived from the NRL-MSISe00 model atmosphere because of the effects of inversion layers and semiannual variability in the lidar data. Relative density fluctuation profiles with 3-km altitude resolution and 1-hour temporal resolution showed the presence of monochromatic gravity waves on almost every night throughout the mesosphere. The prevalent values of vertical wavelength and vertical phase velocity were 12-16 km and 0.5-0.6 m/s, respectively. However, the latter has the significant seasonal variation. Using these two observed parameters, buoyancy periods, and the AGW dispersion relation, we derived the ranges of horizontal wavelength, phase velocity, and source distance. The prevalent values were 550-950 km, 32-35 m/s, and 2500-3500 km, respectively. The potential energy per unit mass Ep showed great night-to-night variability, up to a factor of 20, at all heights. Ep grew at approximately the adiabatic rate below 55-65 km and above 75-80 km. Step function decreases in Ep imply that the AGWs in between gave up considerable energy to the background atmosphere. In addition, Ep varies seasonally. Below 70 km, it has a semiannual variation with a maximum in winter and minima in the equinoxes. At the highest altitudes it has an annual variation with a maximum in winter and a minimum in summer
Quantitative Metrics from 20 Years of Terra Data Usage
NASA's Terra flagship satellite carries five Earth-observing instruments that have collected data for almost 20 years. NASA's Earth Science Data and Information System (ESDIS) Project makes these data, along with derived products, available to worldwide data users. Since the launch of Terra on December 18, 1999, more than 10,000 data products have been archived and distributed by NASA-funded Distributed Active Archive Centers (DAACs) that are part of NASA's Earth Observing System Data and Information System (EOSDIS). At the end of the 2018 Fiscal Year, about 1,000 Terra data products constituted almost 22% of the entire EOSDIS data archive volume (6 PB out of approximately 27.5 PB), and 6 PB of Terra data were distributed to over half-a-million public users worldwide.By categorizing the Terra data products and their distribution, we can get a quantitative assessment of Terra data usage. NASA's ESDIS Project has collected archive, distribution, and user information from EOSDIS data users since February 2000. These metrics are available through the ESDIS Metrics System (EMS). EMS information is stored in a relational database from which quantitative metrics of Terra data use can be retrieved and analyzed.The purposes of this study are to: 1) perform a comprehensive investigation of the 20-year trend in the archive and distribution of Terra data products; 2) identify and characterize data product usage over the last 20 years; and 3) identify and characterize the global user community for these data. In addition to revealing how Terra data use has evolved over time, the results of this study provide insights on identifying the various user communities for different kinds of Earth science data products. Also, because of the enormous quantity of data handled by EOSDIS DAACs, the study provides guidance of the requirements for future data systems that will be needed to effectively and efficiently handle the ever-increasing amounts of Earth science data produced by future (and ongoing) Earth science missions
The Niśvāsamukha, the Introductory book of the Niśvāsatattvasaṃhitā : critical edition, with an introduction and annotated translation appended by Śivadharmasaṅgraha 5–9
A single 9th-century Nepalese palm-leaf manuscript transmits what
appears to be the oldest surviving Śaiva tantra, called the
Niśvāsatattvasaṃhitā. The manuscript consists of five separate books:
Niśvāsamukha, Mūlasūtra, Nayasūtra, Uttarasūtra and Guhyasūtra. The
Niśvāsamukha, which is divided into four chapters to what the text calls
Laukika (lay religion), Vaidika (Vedic), Ādhyātmika (spiritual), and
Atimārga (transcendental), serves as the introductory book prefacing the
Niśvāsatattvasaṃhitā. The Niśvāsamukha introduces the religious context
in which the Mantramārga, the tantric Śaivism that is the subject of
the four sūtras of the Niśvāsatattvasaṃhitā, emerged. The conceptual
framework of the Niśvāsamukha, called the five streams, is reminiscent
of what some would call the inclusivist character of ‘Hinduism’, since
it gives authority to all other systems of thought, at least to some
degree.
Five chapters (5-9) of the Śivadharmasaṅgraha, a work of lay Śaivism,
appear to have borrowed heavily from the Niśvāsamukha. In order to
contextualize the historical evolution of the Niśvāsamukha as a text,
these five chapters are included as an appendix to the edition of the
Niśvāsamukha.
This thesis presents the first critical edition, annotated translation
and study of the Niśvāsamukha.Early Tantra project, the Japan Student Services Organization, the Jan Gonda Fund Foundation, International Institute for Asian Studies and Leiden Institute for Area Studies, SAS India en TibetAsian Studie
Rayleigh-Lidar Determinations of the Vertical Wavelength of Mesospheric Gravity Wave
Atmospheric structures have been observed in the Rayleigh lidar data acquired between 1993 and 2004 at Utah State University (USU). The observations pertain to the density and temperature in the mesosphere between 45 and 90 km altitude. The structures referred to arise from monochromatic Atmospheric Gravity Waves (AGWs). Previous analysis of these data have searched for and found a spectrum with a peak in the vertical wavelength 12–16 km. It has been suggested by other researchers using other types of data that there may be another peak in the spectrum at shorter wavelengths. For this study the lidar data were re- analyzed to search for such waves. To do this, the altitude resolution was reduced from 3 km to 600 m. This enabled the shortest wavelength AGW that can be examined to be reduced from 6 km to ~1.2 km, thereby significantly extending the spectrum investigated. Two additional peaks in the spectrum were found at 1.25–1.75 and 3.0–4.0 km
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Biomass Fuel Use and Cardiac Function in Nepali Women.
BackgroundExposure to household air pollution (HAP) from cooking with biomass fuel affects billions of people. We hypothesized that HAP from woodsmoke, compared to other household fuels, was associated with adverse cardiovascular outcomes, of which there have been few studies.MethodsA cross-sectional study was completed in 299 females aged 40-70 years in Kaski District, Nepal, during 2017-18. All participants underwent a standard 12-lead ECG, ankle and brachial systolic blood pressure measurement, and 2D color and Doppler echocardiography. Current stove type was confirmed by inspection. Blood pressure, height, and weight were measured using a standardized protocol. Hypertension was defined as ≥140/90 mmHg or prior diagnosis. Hemoglobin A1c (HbA1c) was obtained, with diabetes mellitus defined as a prior diagnosis or HbA1C ≥ 6.5%. We used adjusted linear and logistic multivariable regressions to examine the relationship of stove type with cardiac structure and function.ResultsThe majority of women primarily used liquified petroleum gas (LPG) stoves (65%), while 12% used biogas, and 23% used wood-burning cook-stoves. Prevalence of major cardiovascular risk factors was 35% with hypertension, 19% with diabetes mellitus, and 15% current smokers. After adjustment, compared to LPG, wood stove use was associated with increased indexed left atrial volume (β = 3.15, 95% CI 1.22 to 5.09) and increased indexed left ventricular end diastolic volume (β = 7.97, 95% CI 3.11 to 12.83). There was no association between stove type and systemic hypertension, left ventricular mass, systolic dysfunction, diastolic dysfunction, pulmonary hypertension, abnormal ankle-brachial index, or clinically significant ECG abnormalities.ConclusionBiomass fuel use was associated with increased indexed left atrial volume and increased indexed left ventricular diastolic volume in Nepali women, suggesting subclinical adverse cardiac remodeling from HAP in this cross-sectional study. We did not find evidence of an association with hypertension or typical cardiac sequelae of hypertension. Future studies to confirm these results are needed
A study of central galaxy rotation with stellar mass and environment
© 2017. The American Astronomical Society. All rights reserved. We present a pilot analysis of the influence of galaxy stellar mass and cluster environment on the probability of slow rotation in 22 central galaxies at mean redshift z = 0.07. This includes new integral-field observations of five central galaxies selected from the Sloan Digital Sky Survey, observed with the SPIRAL integral-field spectrograph on the Anglo-Australian Telescope. The composite sample presented here spans a wide range of stellar masses, 10.9 < log(M∗/M⊙)lt; 12.0, and are embedded in halos ranging from groups to clusters, 12.9 < log(M 200 Ṁ) < 15.6. We find a mean probability of slow rotation in our sample of P(SR) = 54 ± 7%. Our results show an increasing probability of slow rotation in central galaxies with increasing stellar mass. However, when we examine the dependence of slow rotation on host cluster halo mass, we do not see a significant relationship. We also explore the influence of cluster dominance on slow rotation in central galaxies. Clusters with low dominance are associated with dynamically younger systems. We find that cluster dominance has no significant effect on the probability of slow rotation in central galaxies. These results conflict with a paradigm in which halo mass alone predetermines central galaxy properties
Co-producing principles to guide health research: an illustrative case study from an eating disorder research clinic
There is significant value in co-produced health research, however power-imbalances within research teams can pose a barrier to people with lived experience of an illness determining the direction of research in that area. This is especially true in eating disorder research, where the inclusion of co-production approaches lags other research areas. Appealing to principles or values can serve to ground collaborative working. Despite this, there has not been any prior attempt to co-produce principles to guide the work of a research group and serve as a basis for developing future projects. The aim of this piece of work was to co-produce a set of principles to guide the conduct of research within our lived experience led research clinic, and to offer an illustrative case for the value of this as a novel co-production methodology. A lived experience panel were recruited to our eating disorder research group. Through an iterative series of workshops with the members of our research clinic (composed of a lived experience panel, clinicians, and researchers) we developed a set of principles which we agreed were important in ensuring both the direction of our research, and the way in which we wanted to work together. Six key principles were developed using this process. They were that research should aim to be: 1) real world—offering a clear and concrete benefit to people with eating disorders, 2) tailored—suitable for marginalised groups and people with atypical diagnoses, 3) hopeful—ensuring that hope for recovery was centred in treatment, 4) experiential—privileging the ‘voice’ of people with eating disorders, 5) broad—encompassing non-standard therapeutic treatments and 6) democratic—co-produced by people with lived experience of eating disorders. We reflect on some of the positives as well as limitations of the process, highlighting the importance of adequate funding for longer-term co-production approaches to be taken, and issues around ensuring representation of minority groups. We hope that other health research groups will see the value in co-producing principles to guide research in their own fields, and will adapt, develop, and refine this novel methodology
The Dark Matter halo of the Milky Way, AD 2013
We derive the mass model of the Milky Way (MW) using a cored dark matter (DM) halo profile and recent data. The method used consists in fitting a spherically symmetric model of the Galaxy with a Burkert DM halo profile to available data: MW terminal velocities in the region inside the solar circle, circular velocity as recently estimated from maser star forming regions at intermediate radii, and velocity dispersions of stellar halo tracers for the outermost Galactic region. The latter are reproduced by integrating the Jeans equation for every modeled mass distribution, and by allowing for different velocity anisotropies for different tracer populations. For comparison we also consider a Navarro-Frenk-White profile. We find that the cored profile is the preferred one, with a shallow central density of rho_H~4x10^7M_s/kpc^3 and a large core radius R_H~10 kpc, as observed in external spirals and in agreement with the mass model underlying the Universal Rotation Curve of spirals. We describe also the derived model uncertainties, which are crucially driven by the poorly constrained velocity dispersion anisotropies of halo tracers. The emerging cored DM distribution has implications for the DM annihilation angular profile, which is much less boosted in the Galactic center direction with respect to the case of the standard \Lambda CDM, NFW profile. Using the derived uncertainties we discuss finally the limitations and prospects to discriminate between cored and cusped DM profile with a possible observed diffuse DM annihilation signal. The present mass model aims to characterize the present-day description of the distribution of matter in our Galaxy, which is needed to frame current crucial issues of Cosmology, Astrophysics and Elementary Particles
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