71 research outputs found
Internship Tasks Associated With CIF Icy Regolith Excavation and Volatile Capture Under Vacuum Conditions
Understanding the surface and atmosphere of Mars is critical to current and future development of exploration systems. Dealing with the Martian regolith-the top layer of soil-remains a significant challenge, and much research is still needed. Addressing this need, the Cryogenics Test Lab and Granular Mechanics and Regolith Operations Lab at NASA's Kennedy Space Center are partnering to develop an apparatus that utilizes simulated Martian regolith in an analogous atmospheric environment to gather data about how the material behaves when exposed to water vapor. Martian surface temperatures range from 128 K (-145 C) to 308 K (35 C), and the average pressure is approximately 4.5 Torr; which presents an environment where water can potentially exist in vapor, solid or liquid form. And based on prior Mars missions such as the Phoenix Lander, it is known that water-ice exists just below the surface. This test apparatus will attempt to recreate the conditions that contributed to the Martian ice deposits by exposing a sample to water vapor at low pressure and temperature; thereby forming ice inside the simulant via diffusion. From this, we can better understand the properties and behavior of the regolith, and have more knowledge concerning its ability to store water-and subsequently, how to dig up and extract that water-which will be crucial to sample gathering when the first manned Mars mission takes place
Standing Weight Perception across Unweighted Conditions in a Lower Body Positive Pressure Treadmill
Lower body positive pressure treadmills (LBPP-TM) provide assistive body weight support to the user by forcing air into an inflatable chamber in which the user is secured. The result of this positive pressure can be experienced as a lift to the user. The degree of chamber air pressure (CAP) determines the amount of supportive lift provided with greater and lesser CAP producing more and less lift, respectively. Exercise studies consistently report lower effort perceptions with greater CAP which suggest a reduced physiological and mechanical strain on the body. What is less well known is the effect on resting perceptions of standing weight (SWP). The purpose of this investigation was to examine the perception of resting standing weight across four different weighted conditions in a LBPP-TM. Nine participants (6 female; overall age: 21.3±1.9 years) stood in a LBPP-TM under the following order of body weight set (BWset) conditions: 100%BWset, 70%BWset, 35%BWset, 90%BWset. A portable Davis Vantage weather station barometer measured CAP inside the inflatable chamber and a 10-cm visual analogue scale measured SWP. Repeated measures analysis of variance evidenced significant changes across CAP (100%BWset: 767.5±4.9 mmHg; 70%BWset: 780.0±3.0 mmHg; 35%BWset: 793.5±3.0 mmHg; 90%BWset: 776.4±7.0 mmHg; all ps †0.001) except for the 70%BWset and 90%BWset conditions (p = 0.486) and within SWP (90%BWset: 8.8±1.4 cm vs. 70%BWset: 5.8±2.9 cm, p = 0.011; and 35%BWset: 4.6±3.2 cm, p = 0.007) experimental conditions. LBPP-TMs appear to provide robust manipulations of perception across different experimental contexts. Similar to findings from exercise studies, greater CAP and its resultant lift produced significant reduced perceptions of standing weight while at rest.https://digitalcommons.cortland.edu/slides/1025/thumbnail.jp
Blood Pressure Responses during Three Unweighted Conditions in a Lower Body Positive Pressure Treadmill
During exercise, lower leg muscle activation has been shown to increase venous return, exercise cardiac output, and arterial blood pressure (BP). Here we investigate BP at rest, with an increase in lower body pressure by unweighting volunteers in a lower body positive pressure treadmill (LBPP-TM). The purpose of this study was twofold; to determine if BP changes while standing over five-minute stages in response to four conditions. Nine participants (21.3±1.8 years) stood in a LBPP-TM in the following ordered conditions: 100%BWset (no unweighting, control), 70%BWset, 35%BWset, and 90%BWset (35%BWset is the greatest unweighted condition). A SunTechŸ automatic BP cuff measured systolic and diastolic BP (SBP and DBP, respectively). SBP and DBP was measured once during 100%BWset and averaged over the five-minute stages during 70%BWset, 35%BWset, and 90%BWset. A portable Davis Vantage weather station inside the chamber measured chamber air pressure (CAP). Repeated measures analysis of variance evidenced significant differences in only SBP (p = 0.006) at 100%BWset (no unweighting) and 90%BWset (129±11 mmHg and 120±8 mmHg, respectively). DBP did not show any significant differences across conditions (ps \u3e 0.091). CAP at 100%BWset (767.5±4.9 mmHg) was lower compared to 70%BWset (780.0±3.0 mmHg), 35%BWset (793.5±3.0 mmHg), and 90%BWset (776.4±7.0 mmHg) (p\u3c0.001, p\u3c0.001, and p=0.001, respectively). 35%BWset CAP was also higher than 70%BWset and 90%BWset (ps\u3c0.001 for both), but 70%BWset and 90%BWset CAPs were not different (p = 0.486). The initial findings suggest a quick reduction in CAP (35%BWset to 90%BWset) may decrease SBP below starting levels at 100%BWset. Though the sample consists of healthy, young adults and there was only a 9.0 mmHg decrease in SBP, individuals who are intolerant to SBP changes or older adults may need a slower reduction in CAP from highly unweighted conditions to account for SBP changes as they return to baseline CAP.https://digitalcommons.cortland.edu/slides/1022/thumbnail.jp
An Observed Lack of Substructure in Starless Cores
In this paper we present the results of a high resolution (5") CARMA and SZA
survey of the 3mm continuum emission from 11 of the brightest (at 1.1mm)
starless cores in the Perseus molecular cloud. We detect 2 of the 11 cores,
both of which are composed of single structures, and the median 3 sigma upper
limit for the non-detections is 0.2 M_sun in a 5" beam. These results are
consisent with, and as stringent as, the low detection rate of compact 3mm
continuum emission in dense cores in Perseus reported by Olmi et al. (2005).
From the non-detection of multiple components in any of the eleven cores we
conclude that starless core mass functions derived from bolometer maps at
resolutions from 10"-30" (e.g. with MAMBO, SCUBA or Bolocam) are unlikely to be
significantly biased by the blending of lower mass cores with small
separations. These observations provide additional evidence that the majority
of starless cores in Perseus have inner density profiles shallower than r^-2.Comment: 9 pages, including 3 figures and 3 tables. Accepted to Ap
The EDGE-CALIFA Survey: Interferometric Observations of 126 Galaxies with CARMA
We present interferometric CO observations, made with the Combined Array for Millimeter-wave Astronomy (CARMA) interferometer, of galaxies from the Extragalactic Database for Galaxy Evolution survey (EDGE). These galaxies are selected from the Calar Alto Legacy Integral Field Area (CALIFA) sample, mapped with optical integral field spectroscopy. EDGE provides good-quality CO data (3Ï sensitivity before inclination correction, resolution âŒ1.4 kpc) for 126 galaxies, constituting the largest interferometric CO survey of galaxies in the nearby universe. We describe the survey and data characteristics and products, then present initial science results. We find that the exponential scale lengths of the molecular, stellar, and star-forming disks are approximately equal, and galaxies that are more compact in molecular gas than in stars tend to show signs of interaction. We characterize the molecular-to-stellar ratio as a function of Hubble type and stellar mass and present preliminary results on the resolved relations between the molecular gas, stars, and star-formation rate. We then discuss the dependence of the resolved molecular depletion time on stellar surface density, nebular extinction, and gas metallicity. EDGE provides a key data set to address outstanding topics regarding gas and its role in star formation and galaxy evolution, which will be publicly available on completion of the quality assessment.Fil: Bolatto, Alberto. University of Maryland; Estados UnidosFil: Wong, Tony. University of Illinois at Urbana; Estados UnidosFil: Utomo, Dyas. University of California at Berkeley; Estados UnidosFil: Blitz, Leo. University of California at Berkeley; Estados UnidosFil: Vogel, Stuart N.. University of Maryland; Estados UnidosFil: SĂĄnchez, SebastiĂĄn F.. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Barrera-Ballesteros, Jorge. University Johns Hopkins; Estados UnidosFil: Cao, Yixian. University of Illinois; Estados UnidosFil: Colombo, Dario. Max Planck Institut Fur Radioastronomie; AlemaniaFil: Dannerbauer, Helmut. Universidad de La Laguna; EspañaFil: GarcĂa-Benito, RubĂ©n. Instituto de AstrofĂsica de AndalucĂa; EspañaFil: Herrera-Camus, Rodrigo. Max Planck Institute fĂŒr Extraterrestrische Physik; AlemaniaFil: Husemann, Bernd. Max-Planck-Institut fĂŒr Astronomie; AlemaniaFil: Kalinova, Veselina. Max Planck Institut fĂŒr Radioastronomie; AlemaniaFil: Leroy, Adam K.. Ohio State University; Estados UnidosFil: Leung, Gigi. Max-Planck-Institut fĂŒr Astronomie; AlemaniaFil: Levy, Rebecca C.. University of Maryland; Estados UnidosFil: Mast, Damian. Observatorio Astronomico de la Universidad Nacional de Cordoba; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - CĂłrdoba; ArgentinaFil: Ostriker, Eve. University of Princeton; Estados UnidosFil: Rosolowsky, Erik. University of Alberta; CanadĂĄFil: Sandstrom, Karin M.. University of California at San Diego; Estados UnidosFil: Teuben, Peter. University of Maryland; Estados UnidosFil: Van De Ven, Glenn. Max-Planck-Institut fĂŒr Astronomie; AlemaniaFil: Walter, Fabian. Max-Planck-Institut fĂŒr Astronomie; Alemani
Hierarchical Structure of Magnetohydrodynamic Turbulence In Position-Position-Velocity Space
Magnetohydrodynamic turbulence is able to create hierarchical structures in
the interstellar medium that are correlated on a wide range of scales via the
energy cascade. We use hierarchical tree diagrams known as dendrograms to
characterize structures in synthetic Position-Position-Velocity (PPV) emission
cubes of optically thin isothermal magnetohydrodynamic turbulence. We show that
the structures and degree of hierarchy observed in PPV space are related to the
physics of the gas, i.e. self-gravity and the global sonic and Alfvenic Mach
number. Simulations with higher Alfvenic Mach number, self-gravity and
supersonic flows display enhanced hierarchical structure. We observed a strong
sonic and Alfvenic dependency when we apply the the statistical moments (i.e.
mean, variance, skewness, kurtosis) to the dendrogram distribution. Larger
magnetic field and sonic Mach number correspond to larger values of the
moments. Application of the dendrogram to 3D density cubes, also known as
Position-Position-Position cubes (PPP), reveals that the dominant emission
contours in PPP and PPV are related for supersonic gas but not for subsonic. We
also explore the effects of smoothing, thermal broadening and velocity
resolution on the dendrograms in order to make our study more applicable to
observational data. These results all point to hierarchical tree diagrams as
being a promising additional tool for studying ISM turbulence and star forming
regions in the direction of obtaining information on the degree of
self-gravity, the Mach numbers and the complicated relationship between PPV and
PPP.Comment: submitted to Ap
The EDGE-CALIFA Survey: Spatially Resolved 13CO(1-0) Observations and Variations in 12CO(1-0)/13CO(1-0) in Nearby Galaxies on kpc Scales
We present 13CO(1-0) observations for the EDGE-CALIFA survey, which is a
mapping survey of 126 nearby galaxies at a typical spatial resolution of 1.5
kpc. Using detected 12CO(1-0) emission as a prior, we detect 13CO(1-0) in 41
galaxies via integrated line flux over the entire galaxy, and in 30 galaxies
via integrated line intensity in resolved synthesized beams. Incorporating our
CO observations and optical IFU spectroscopy, we perform a systematic
comparison between the line ratio R12/13 and the properties of the stars and
ionized gas. Higher R12/13 values are found in interacting galaxies than in
non-interacting galaxies. The global R12/13 slightly increases with infrared
color F60/F100, but appears insensitive to other host galaxy properties such as
morphology, stellar mass, or galaxy size. We also present annulus-averaged
R12/13 profiles for our sample up to a galactocentric radius of 0.4r25 (~6
kpc), taking into account the 13CO(1-0) non-detections by spectral stacking.
The radial profiles of R12/13 are quite flat across our sample. Within
galactocentric distances of 0.2r25, azimuthally-averaged R12/13 increases with
star formation rate. However, the Spearman rank correlation tests show the
azimuthally-averaged R12/13 does not strongly correlate with any other gas or
stellar properties in general, especially beyond 0.2r25 from the galaxy
centers. Our findings suggest that in the complex environments in galaxy disks,
R12/13 is not a sensitive tracer for ISM properties. Dynamical disturbances,
like galaxy interactions or the presence of a bar, also have an overall impact
on R12/13, which further complicate the interpretations of R12/13 variations.Comment: 35pages, 11 figure, 6 tables, accepted for publication in ApJ
PHF-Core Tau as the Potential Initiating Event for Tau Pathology in Alzheimerâs Disease
FUNDING This work was supported by Fondo Nacional de Ciencia, Tecnologia, FONDOCyT, from the Ministry of Higher Education, Science and Technology, Dominican Republic (2015- 3A2-127 to MP-H and 2018-2019-2A3-208 to JL-M and MP-H). ACKNOWLEDGMENTS: We want to express our gratitude to the following: Dr. P. Davies (Albert Einstein College of Medicine, Bronx, NY, United States) and Lester I. Binderâ (North Western, Chicago, IL, United States) for the generous gifts of mAbs TG3 and Alz-50, and Tau-1, Tau-5, and Tau-7, respectively; Tec. Amparo Viramontes Pintos for the handling of the brain tissue; Samadhi Moreno-Campuzano for her technical assistance/support in the confocal microscopy unit of CIIDIR Durango, Instituto PolitĂ©cnico Nacional; Union Medical University Clinic, Dominican Republic, for their support and collaboration in the development of this research project. We also want to express our gratitude to the Mexican families who have donated the brain of their loved ones affected with Alzheimerâs disease and made our research possible. This work is dedicated to the memory of Professor Dr. JosĂ© RaĂșl Mena LĂłpezâ .Peer reviewedPublisher PD
Motivations and Preliminary Design for Mid-Air Deployment of a Science Rotorcraft on Mars
Mid-Air Deployment (MAD) of a rotorcraft during Entry, Descent and Landing (EDL) on Mars eliminates the need to carry a propulsion or airbag landing system. This reduces the total mass inside the aeroshell by more than 100 kg and simplifies the aeroshell architecture. MADâs lighter and simpler design is likely to bring the risk and cost associated with the mission down. Moreover, the lighter entry mass enables landing in the Martian highlands, at elevations inaccessible to current EDL technologies. This paper proposes a novel MAD concept for a Mars helicopter. We suggest a minimum science payload package to perform relevant science in the highlands. A variant of the Ingenuity helicopter is proposed to provide increased deceleration during MAD, and enough lift to fly the science payload in the highlands. We show in simulation that the lighter aeroshell results in a lower terminal velocity (30 m/s) at the end of the parachute phase of the EDL, and at higher altitudes than other approaches. After discussing the aerodynamics, controls, guidance, and mechanical challenges associated with deploying at such speed, we propose a backshell architecture that addresses them to release the helicopter in the safest conditions. Finally, we implemented the helicopter model and aerodynamic descent perturbations in the JPL Dynamics and Real-Time Simulation (DARTS)framework. Preliminary performance evaluation indicates landing and helicopter operations can be achieved up to +5 km MOLA (Mars Orbiter Laser Altimeter reference)
Unexpected Widespread Hypophosphatemia and Bone Disease Associated with Elemental Formula Use in Infants and Children
OBJECTIVE: Hypophosphatemia occurs with inadequate dietary intake, malabsorption, increased renal excretion, or shifts between intracellular and extracellular compartments. We noticed the common finding of amino-acid based elemental formula [EF] use in an unexpected number of cases of idiopathic hypophosphatemia occurring in infants and children evaluated for skeletal disease. We aimed to fully characterize the clinical profiles in these cases.
METHODS: A retrospective chart review of children with unexplained hypophosphatemia was performed as cases accumulated from various centres in North America and Ireland. Data were analyzed to explore any relationships between feeding and biochemical or clinical features, effects of treatment, and to identify a potential mechanism.
RESULTS: Fifty-one children were identified at 17 institutions with EF-associated hypophosphatemia. Most children had complex illnesses and had been solely fed NeocateÂź formula products for variable periods of time prior to presentation. Feeding methods varied. Hypophosphatemia was detected during evaluation of fractures or rickets. Increased alkaline phosphatase activity and appropriate renal conservation of phosphate were documented in nearly all cases. Skeletal radiographs demonstrated fractures, undermineralization, or rickets in 94% of the cases. Although the skeletal disease had often been attributed to underlying disease, most all improved with addition of supplemental phosphate or change to a different formula product.
CONCLUSION: The observed biochemical profiles indicated a deficient dietary supply or severe malabsorption of phosphate, despite adequate formula composition. When transition to an alternate formula was possible, biochemical status improved shortly after introduction to the alternate formula, with eventual improvement of skeletal abnormalities. These observations strongly implicate that bioavailability of formula phosphorus may be impaired in certain clinical settings. The widespread nature of the findings lead us to strongly recommend careful monitoring of mineral metabolism in children fed EF. Transition to alternative formula use or implementation of phosphate supplementation should be performed cautiously with as severe hypocalcemia may develop
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