939 research outputs found
Planetary benchmarks
Design criteria and technology requirements for a system of radar reference devices to be fixed to the surfaces of the inner planets are discussed. Offshoot applications include the use of radar corner reflectors as landing beacons on the planetary surfaces and some deep space applications that may yield a greatly enhanced knowledge of the gravitational and electromagnetic structure of the solar system. Passive retroreflectors with dimensions of about 4 meters and weighing about 10 kg are feasible for use with orbiting radar at Venus and Mars. Earth-based observation of passive reflectors, however, would require very large and complex structures to be delivered to the surfaces. For Earth-based measurements, surface transponders offer a distinct advantage in accuracy over passive reflectors. A conceptual design for a high temperature transponder is presented. The design appears feasible for the Venus surface using existing electronics and power components
Preliminary comparison of 3.5-cm and 12.6-cm wavelength continuous wave observations of Mars
Radar observations of Mars at Goldstone in 1990 were conducted by transmitting pure sinusoidal signals at 3.5-cm wavelengths and receiving the Doppler-spread echoes from Mars at Earth. Radar transmissions were circularly polarized and the echoes recorded in two senses: depolarized and polarized. Latitudes of the subradar points are between 3.5 deg and 11.1 deg S; longitude coverage is discontinuous. The observed depolarized and polarized echo total cross-sections and their ratios for two wavelengths were compared and discussed
Опухоль брюшной стенки - грыжа спигелевой линии, содержащая метастатическую карциному с невыявленным первичным очагом
АДЕНОКАРЦИНОМАБРЮШНАЯ СТЕНКАГРЫЖИКАРЦИНОМАКОЛОРЕКТАЛЬНЫЕ НОВООБРАЗОВАНИЯНОВООБРАЗОВАНИЯТОЛСТАЯ КИШК
Comparison of Inedible Egg Product and Spray-Dried Plasma as Sources of Protein for Weanling Pigs
Pigs were weaned at approximately 18 days of age and fed diets containing inedible egg product, spray-dried plasma (SDP), or the combination of both for 2 weeks postweaning. They then received a common diet for an additional 2 weeks after the treatment period. The impact of these dietary ingredients on growth performance was evaluated.
Inedible egg product did not improve growth or feed efficiency of pigs compared with those fed the control diet during the 2-week treatment period. However, SDP increased body weight gain and feed efficiency during the treatment period. The improved performance over the control group that resulted from feeding a combination of SDP and egg product was primarily dependent upon the SDP. In the third week, a trend occurred for improved performance of pigs fed the egg product compared with those fed 4% SDP; however, the difference was not significant. During this same period, pigs previously fed SDP gained weight slower and consumed less feed than those that had not been fed SDP. Therefore, the response to SDP was partially lost when it was removed from the diet. In summary, the outcome of this study demonstrated that inedible egg product was an adequate source of protein for the weanling pig but did not provide measurable improvements over the control diet. Inedible egg product did not have an additive effect when combined with SDP. The improved feed efficiency associated with SDP resulted in increased weanling pig growth
Wavelet Based Fractal Analysis of Airborne Pollen
The most abundant biological particles in the atmosphere are pollen grains
and spores. Self protection of pollen allergy is possible through the
information of future pollen contents in the air. In spite of the importance of
airborne pol len concentration forecasting, it has not been possible to predict
the pollen concentrations with great accuracy, and about 25% of the daily
pollen forecasts have resulted in failures. Previous analysis of the dynamic
characteristics of atmospheric pollen time series indicate that the system can
be described by a low dimensional chaotic map. We apply the wavelet transform
to study the multifractal characteristics of an a irborne pollen time series.
We find the persistence behaviour associated to low pollen concentration values
and to the most rare events of highest pollen co ncentration values. The
information and the correlation dimensions correspond to a chaotic system
showing loss of information with time evolution.Comment: 11 pages, 7 figure
North-South cooperation through BIOTA: An interdisciplinary monitoring programme in arid and semi-arid southern Africa
Connecting disciplines in a north– South collaboration has many advantages: mutualisms evolve, synergies are created and spin-offs emerge. The BIOTA South (Biodiversity Monitoring Transect Analysis in southern Africa) programme, with its long-term vision to generate knowledge of biodiversity along a north–south transect in southern Africa, is providing opportunities for research, technology transfer and capacity building while focusing on potential solutions for critical challenges that face this environmentally vulnerable part of the subcontinen
Mechanisms of Fetal Programming in Hypertension
Events that occur in the early fetal environment have been linked to long-term health and lifespan consequences in the adult. Intrauterine growth restriction (IUGR), which may occur as a result of nutrient insufficiency, exposure to hormones, or disruptions in placental structure or function, may induce the fetus to alter its developmental program in order to adapt to the new conditions. IUGR may result in a decrease in the expression of genes that are responsible for nephrogenesis as nutrients are rerouted to the development of more essential organs. Fetal survival under these conditions often results in low birth weight and a deficit in nephron endowment, which are associated with hypertension in adults. Interestingly, male IUGR offspring appear to be more severely affected than females, suggesting that sex hormones may be involved. The processes of fetal programming of hypertension are complex, and we are only beginning to understand the underlying mechanisms
LACHESIS restricts gametic cell fate in the female gametophyte of Arabidopsis
In flowering plants, the egg and sperm cells form within haploid gametophytes. The female gametophyte of Arabidopsis consists of two gametic cells, the egg cell and the central cell, which are flanked by five accessory cells. Both gametic and accessory cells are vital for fertilization; however, the mechanisms that underlie the formation of accessory versus gametic cell fate are unknown. In a screen for regulators of egg cell fate, we isolated the lachesis (lis) mutant which forms supernumerary egg cells. In lis mutants, accessory cells differentiate gametic cell fate, indicating that LIS is involved in a mechanism that prevents accessory cells from adopting gametic cell fate. The temporal and spatial pattern of LIS expression suggests that this mechanism is generated in gametic cells. LIS is homologous to the yeast splicing factor PRP4, indicating that components of the splice apparatus participate in cell fate decisions
Language from Police Body Camera Footage Shows Racial Disparities in Officer Respect
Using footage from body-worn cameras, we analyze the respectfulness of police officer language toward white and black community members during routine traffic stops. We develop computational linguistic methods that extract levels of respect automatically from transcripts, informed by a thin-slicing study of participant ratings of officer utterances. We find that officers speak with consistently less respect toward black versus white community members, even after controlling for the race of the officer, the severity of the infraction, the location of the stop, and the outcome of the stop. Such disparities in common, everyday interactions between police and the communities they serve have important implications for procedural justice and the building of police–community trust
Groundwater residence time estimates obscured by anthropogenic carbonate
© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Seltzer, A. M., Bekaert, D. V., Barry, P. H., Durkin, K. E., Mace, E. K., Aalseth, C. E., Zappala, J. C., Mueller, P., Jurgens, B., & Kulongoski, J. T. Groundwater residence time estimates obscured by anthropogenic carbonate. Science Advances, 7(17), (2021): eabf3503, https://doi.org/10.1126/sciadv.abf3503.Groundwater is an important source of drinking and irrigation water. Dating groundwater informs its vulnerability to contamination and aids in calibrating flow models. Here, we report measurements of multiple age tracers (14C, 3H, 39Ar, and 85Kr) and parameters relevant to dissolved inorganic carbon (DIC) from 17 wells in California’s San Joaquin Valley (SJV), an agricultural region that is heavily reliant on groundwater. We find evidence for a major mid-20th century shift in groundwater DIC input from mostly closed- to mostly open-system carbonate dissolution, which we suggest is driven by input of anthropogenic carbonate soil amendments. Crucially, enhanced open-system dissolution, in which DIC equilibrates with soil CO2, fundamentally affects the initial 14C activity of recently recharged groundwater. Conventional 14C dating of deeper SJV groundwater, assuming an open system, substantially overestimates residence time and thereby underestimates susceptibility to modern contamination. Because carbonate soil amendments are ubiquitous, other groundwater-reliant agricultural regions may be similarly affected.his work was conducted as a part of the USGS National Water Quality Assessment Program (NAWQA) Enhanced Trends Project (https://water.usgs.gov/nawqa/studies/gwtrends/). Measurements at Argonne National Laboratory were supported by Department of Energy, Office of Science under contract DE-AC02-06CH11357. Measurements at Pacific Northwest National Laboratory were part of the Ultra-Sensitive Nuclear Measurements Initiative conducted under the Laboratory Directed Research and Development Program. PNNL is operated by Battelle for the U.S. Department of Energy under Contract DE-AC05-76RL01830. This work was also partially supported by NSF award OCE-1923915 (to A.M.S. and P.H.B. at WHOI)
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