434 research outputs found
Radio detection of H2O in comet Bradfield (1974b)
Results of observations of comet Bradfield using the Haystack telescope are summarized with emphasis on the detection of the 1.35 cm emission line of water in the comet. The excitation of water and methyl cyanide in comets is briefly considered
Invertebrate predation in Lake Michigan: Regulation of Bosmina longirostris by Leptodora kindtii
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110049/1/lno19913630483.pd
The Stabilizing Effectiveness of Conical Flares on Bodies with Conical Noses
An analysis is presented of published results of force tests on 80 cone-cylinder-flare configurations at Mach numbers of 2.18, 2.81, and 4.04. The contributions, excluding interference effects, of the cone-cylinder bodies to the over-all normal force derivatives have been removed by means of the second-order shock-expansion method, and the normal force derivatives at zero angle of attack due to the flares alone are shown. The results from a wide variety of configurations are correlated by plotting ratios of the normal force derivatives of the flares to the normal force derivatives of cones having the same included angle. Comparisons are made of the experimental normal force results with the normal force derivatives obtained by assuming conical flow over the flares and with those obtained by use of the second-order shock-expansion method. The comparisons show that use of the second-order shock-expansion method is generally the superior of the two, and in most cases gives values of the normal force derivatives of the flares which agree very well with the experimental results. Centers of pressure of the flares are presented and comparisons are made with results obtained from the theories mentioned. In general, the comparisons show that the assumption of conical flow over the flares is comparable to use of the second-order shock-expansion method in determining the centers of pressure, and in many cases both methods give values which agree closely with the experimental results
Earthworm populations in a wheat-soybean double-crop system under seven years of established residue management practices
Earthworms improve soil structure, distribute litter and microbes, stimulate microbial activity, facilitate decomposition, and increase nitrogen (N) availability for plant growth. Earthworm density is often reduced in low organic matter soils that are intensively managed to grow row crops. This study was designed to relate earthworm density and community composition to residue management after seven years of established management practices in a wheat (Triticum aestivum L.)-soybean (Glycine max (L.) Merr.) double-crop system maintained in Marianna, Ark. Residue management practices included conventional tillage (CT) and no-tillage (NT), N fertilization to produce high and low wheat residue amounts left in the field, and burning and non-burning of residue after wheat harvest. Total earthworm densities ranged from 271 to 508 m-2 across treatments. Both exotic Aporrectodea trapezoides (Duges) and native Diplocardia sylvicola (Gates) adult earthworms were present with very little difference in diversity among sampled communities; however, more than 50 % of adults were D. sylvicola in all treatments. Residue level and burning influenced total, juvenile, and native earthworm densities differently in CT and NT. Adult native earthworms predominated over a common exotic species in a wheat-soybean double-crop system in Arkansas with residue management practices interacting to impact the density of earthworms
On the formation of graphite grains in cool stars
Graphite grain formation in cool stars examined on basis of molecular equilibrium data for stellar atmosphere
Superhumps in Cataclysmic Binaries. XXII. 1RXS J232953.9+062814
We report photometry of 1RXS J232953.9+062814, a recently discovered dwarf
nova with a remarkably short 64.2-minute orbital period. In quiescence, the
star's light curve is that of a double sinusoid, arising from the "ellipsoidal"
distortion of the Roche-lobe-filling secondary. During superoutburst, common
superhumps develop with a period 3-4% longer than P_orb. This indicates a mass
ratio M_2/M_1=0.19+-0.02, a surprisingly large value in so compact a binary.
This implies that the secondary star has a density 2-3 times higher than that
of other short-period dwarf novae, suggesting a secondary enriched by H-burning
prior to the common-envelope phase of evolution. We estimate i=50+-5 deg,
M_1=0.63 (+0.12, -0.09) M_sol, M_2=0.12 (+0.03, -0.02) M_sol, R_2=0.121
(+0.010, -0.007) R_sol, and a distance to the binary of 180+-40 pc.Comment: PDF, 17 pages, 3 tables, 5 figures; accepted, in press, to appear
June 2002, PASP; more info at http://cba.phys.columbia.edu
Climatic controls on diffuse groundwater recharge across Australia
Reviews of field studies of groundwater recharge have attempted to investigate how climate characteristics control recharge, but due to a lack of data have not been able to draw any strong conclusions beyond that rainfall is the major determinant. This study has used numerical modelling for a range of Köppen-Geiger climate types (tropical, arid and temperate) to investigate the effect of climate variables on recharge for different soil and vegetation types. For the majority of climate types, the correlation between the modelled recharge and total annual rainfall is weaker than the correlation between recharge and the annual rainfall parameters reflecting rainfall intensity. Under similar soil and vegetation conditions for the same annual rainfall, annual recharge in regions with winter-dominated rainfall is greater than in regions with summer-dominated rainfall. The importance of climate parameters other than rainfall in recharge estimation is highest in the tropical climate type. Mean annual values of solar radiation and vapour pressure deficit show a greater importance in recharge estimation than mean annual values of the daily mean temperature. Climate parameters have the lowest relative importance in recharge estimation in the arid climate type (with cold winters) and the temperate climate type. For 75% of all soil, vegetation and climate types investigated, recharge elasticity varies between 2 and 4 indicating a 20% to 40% change in recharge for a 10% change in annual rainfall. Understanding how climate controls recharge under the observed historical climate allows more informed choices of analogue sites if they are to be used for climate change impact assessments
Halal logistics legal framework: Malaysia perspective
Halal logistics is one of the profitable industries in Malaysia with demand from local and international clients. Though there are regulations and standards protecting this industry, the enforcement on these two demands attention and further study as there are still reports of abuse of the Halal logo due to failure to segregation of halal and non-halal products during the logistics chains. Currently, there are very limited literature review on enforcement of halal logistics. Hence, this research seeks to discover the critical factors for effective enforcement of halal logistics in Malaysia. Applying a qualitative method, semi-structured interviews were conducted with stakeholders of the industry. Besides that, references were made to previous publication, case laws and legal documents. The interviews were recorded, transcribed, coded and reconciled. By using Nvivo software (12 Plus), the researcher coded the transcriptions and identify the themes and sub-themes. The findings discovered the following elements as critical within the industry: First the source of laws applicable in halal logistics, the duties and responsibilities of legal agencies and the due process (legal proceedings). This research will focus on the critical elements which are the sources of laws and the due process. The result shows that with regards to the sources of law, all participants agreed criminal laws are applicable in Halal logistics cases. However, only the academician and Halal logistics operator agreed civil laws should be included. Moreover, they also concurred that inclusive application of civils laws should also extend legal exposure to the halal logistics operators in order to manage the activities and avoid mistakes and cross-contamination
Real-time analysis of gene regulation by glucocorticoid hormones
There is increasing evidence that temporal factors are important in allowing
cells to gain additional information from external factors, such as hormones and
cytokines. We sought to discover how cell responses to glucocorticoids develop
over time, and how the response kinetics vary according to ligand structure and
concentration, and hence have developed a continuous gene transcription
measurement system, based on an interleukin-6 (IL-6) luciferase reporter gene.
We measured the time to maximal response, maximal response and integrated
response, and have compared these results with a conventional, end point
glucocorticoid bioassay. We studied natural glucocorticoids (corticosterone and
cortisol), synthetic glucocorticoids (dexamethasone) and glucocorticoid
precursors with weak, or absent bioactivity. We found a close correlation
between half maximal effective concentration (EC50) for maximal response, and
for integrated response, but with consistently higher EC50 for the latter. There
was no relation between the concentration of ligand and the time to maximal
response. A comparison between conventional end point assays and real-time
measurement showed similar effects for dexamethasone and hydrocortisone, with a
less effective inhibition of IL-6 seen with corticosterone. We profiled the
activity of precursor steroids, and found pregnenolone, progesterone,
21-hydroxyprogesterone and 17-hydroxyprogesterone all to be ineffective in the
real-time assay, but in contrast, progesterone and 21-hydroxyprogesterone showed
an IL-6 inhibitory activity in the end point assay. Taken together, our data
show how ligand concentration can alter the amplitude of glucocorticoid
response, and also that a comparison between real-time and end point assays
reveals an unexpected diversity of the function of glucocorticoid precursor
steroids, with implications for human disorders associated with their
overproduction
Contribution of forest foods to dietary intake and their association with household food insecurity: a cross-sectional study in women from rural Cameroon
To determine the contribution of forest foods to dietary intake and estimate their association with household food insecurity.
Cross-sectional survey conducted among 279 households. Using a 7 d recall questionnaire, information on household food consumption was collected from women and used to determine the household dietary diversity score, food variety score and forest food consumption score (FFCS). Household Food Insecurity Access Scale (HFIAS) score was determined and Spearman rank correlation was used to establish the relationship between consumption of forest foods and HFIAS score. Womenâs dietary intake was estimated from two 24 h recalls. The contribution of forest foods to womenâs nutrient intakes was calculated and womenâs nutrient intakes were compared with estimated average nutrient requirements.
Rural forest-dependent households in twelve villages in eastern and southern Cameroon. Household heads and their non-pregnant, non-lactating spouses.
Forty-seven unique forest foods were identified; of these, seventeen were consumed by 98 % of respondents over the course of one week and by 17 % of women during the two 24 h recall periods. Although forest foods contributed approximately half of womenâs total daily energy intake, considerably greater contributions were made to vitamin A (93 %), Na (100 %), Fe (85 %), Zn (88 %) and Ca (89 %) intakes. Despite a highly biodiverse pool of foods, most households (83 %) suffered from high food insecurity based on the HFIAS. A significant inverse correlation was observed between the HFIAS score and the FFCS (r2=â0·169, P=0·0006), demonstrating that forest foods play an important role in ensuring food security in these forest-dependent communities.
Forest foods are widely consumed by forest-dependent communities. Given their rich nutrient content, they have potential to contribute to food and nutrition security
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