2,724 research outputs found

    The road to hormonal male contraception: end in sight?

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    The concept of a hormonal approach that sufficiently and reversibly suppresses spermatogenesis to the level required for effective contraception has been developed and tested over several decades. The reality of achieving this has been confirmed using both testosterone alone and combination methods using a progestogen with a physiological dose of testosterone, necessary to replace the lack of endogenous testosterone production by the suppressed testes. A range of both long-acting and self-administered combination methods are effective, including injection, implant and gel methods of administration, with up to 95% of men achieving sufficient spermatogenic suppression. New steroids are also being trialled. Surveys show the widespread willingness of men and their female partners to use novel male methods, suggesting the potential of this approach to contribute to global family planning and sustainable development goals. This approach to contraception can clearly be effective, and needs to move from relatively small scale testing to large scale pre-marketing trials: only then can information about long-term safety and real-world acceptability be obtained

    The lipid content and fatty acid composition of hatched second stage juveniles of Globodera rostochiensis and G. pallida

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    Les juvéniles de deuxième stade (J2) de #Globodera rostochiensisa^geˊsdunjour(eˊclosdanslesdiffusatsderacinesdepommedeterre)contiennentenmoyenne29,2 âgés d'un jour (éclos dans les diffusats de racines de pomme de terre) contiennent en moyenne 29,2% de lipides (poids sec), tandis que ceux de #G. pallida en contiennent en moyenne 27,2%. Les lipides des J2 de #G. rostochiensisJ2sontcomposeˊsde72,8 J2 sont composés de 72,8% de lipides neutres, 11,3% d'acides gras libres et 15,9% de phospholipides. La fraction lipidique neutre comprend elle-même 95,5% de triacylglycérides, 1,8% de diacylglycérides, 2,3% de monoacylglycérides et 0,4% d'ester de cholestérol. Les lipides de #G. pallida J2 sont composés de 73,0% de lipides neutres, 13,2% d'acides gras libres et 13,8% de phospholipides. 77,4% des acides gras totaux de #G. rostochiensiset80,6 et 80,6% de ceux de #G. pallida sont insaturés. Les deux espèces présentent un profil d'acides gras similaire. Vingt acides gras ont été identifiés, allant de C14 à C22 ; les principales classes de lipides sont surtout composées d'acides gras en C20 (50-60%) et C18 (30-35%). Les trois acides gras les plus abondants caractérisés chez les deux espèces sont C20:4, C20:1 et C18:1, représentant à eux seuls plus de 60% du total. Les J2 de #G. rostochiensis$ récoltés toutes les 24 heures au cours des première et seconde semaines après l'exposition aux PRD, présentent la même composition en acides gras que les J2 récoltés toutes les 96 heures pendant les troisième et quatrième semaines. (Résumé d'auteur

    A simple two-module problem to exemplify building-block assembly under crossover

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    Theoretically and empirically it is clear that a genetic algorithm with crossover will outperform a genetic algorithm without crossover in some fitness landscapes, and vice versa in other landscapes. Despite an extensive literature on the subject, and recent proofs of a principled distinction in the abilities of crossover and non-crossover algorithms for a particular theoretical landscape, building general intuitions about when and why crossover performs well when it does is a different matter. In particular, the proposal that crossover might enable the assembly of good building-blocks has been difficult to verify despite many attempts at idealized building-block landscapes. Here we show the first example of a two-module problem that shows a principled advantage for cross-over. This allows us to understand building-block assembly under crossover quite straightforwardly and build intuition about more general landscape classes favoring crossover or disfavoring it

    DNA sequences required for regulated expression of β-globin genes in murine erythroleukaemia cells.

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    We introduced into MEL cells rabbit beta-globin gene deletion mutants and two sets of hybrid genes constructed from the inducible human beta-globin gene and noninducible human gamma-globin gene or the murine H-2Kbm1 class I MHC gene. S1 nuclease analysis of gene transcripts before and after MEL differentiation showed that induction of the rabbit beta-globin gene did not require more than 58 bp of DNA 5' to the transcription initiation site. Hybrid genes were constructed with human beta-globin DNA sequences from either 5' or 3' of the translation initiation site linked to the complementary parts of the gamma or H2Kbm1 genes. Both types of constructs were inducible during MEL differentiation. The relative rates of transcription of the 5' gamma-3' beta and 5'H2-3' beta hybrid genes show that induction of the hybrid gene transcripts results at least in part from transcriptional activation of the genes. We suggest that DNA sequences that regulate beta-globin gene transcription during MEL differentiation are located both 5' and 3' to the translation initiation site

    Air Temperature and Vapor Pressure Changes Caused by Sprinkler Irrigation

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    The downwind effect of evaporation from sprinkler spray was studied in the field to determine if air temperature and vapor pressure were changed enough to influence plant growth and water use. Wet-bulb and dry-bulb temperature profiles were measured upwind and at three distances downwind from a sprinkler lateral before and during sprinkling. Wind-speed and direction were also measured. Air temperature generally was reduced less than 1 C, and vapor pressure in the air was increased less than 0.8 mb. This amount of change in the air temperature and humidity is not likely to be sufficient to cause any significant change in plant growth or evaporative loss of water

    The empirical relevance of the competitive storage model

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    "The empirical relevance of models of competitive storage arbitrage in explaining commodity price behavior has been seriously challenged in a series of pathbreaking papers by Deaton and Laroque (1992, 1995, 1996). Here we address their major criticism, that the model is in general unable to explain the degree of serial correlation observed in prices of twelve major commodities. First, we present a simple numerical version of their model which, contrary to Deaton and Laroque (1992), can generate the high levels of serial correlation observed in commodity prices, if it is parameterized to generate realistic levels of price variation. Then, after estimating the Deaton and Laroque (1995, 1996) model using their data set, model specification and econometric approach, we show that use of a much finer grid to approximate the equilibrium price function yields quite different estimates for most commodities. Results are obtained for coffee, copper, jute, maize, palm oil, sugar and tin that support the specifications of the storage model with positive constant marginal storage cost and no deterioration as in Gustafson (1958a). Consumption demand has low response to price and, except for sugar, there are infrequent stockouts. Observed magnitudes of serial correlation of price match those implied by the estimated model." [author's abstract

    Onion Seed Yield and Quality as Affected by Irrigation Management

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    The effects of soil moisture, sprinkler irrigation, and misting (5 min at 30-min intervals) on hybrid onion-seed (Allium cepa L.) production were evaluated at Kimberly, Idaho. Sprinkling and misting treatments were included to determine if sprinkler irrigation could be used for onion-seed production, and if evaporative cooling (misting) would alleviate the scalding of umbels at excessively high temperatures. Results showed that reasonable onionseed yields could be obtained with sprinkler irrigation in spite of anticipated adverse effects on pollination. In areas with high daytime temperatures, misting could be used to cool the umbels, as much as 15 C for about 20 min, although it does not seem necessary for the low 32 to 35 C daytime temperatures at Kimbqly. The highest anion-seed yields were obtained with the furrow-irrigation treatment where water was applied when tensiometers at 20-cm depth read about 0.5 bar soil moisture tension (furrow adequate). The addition of misting to furrow irrigation decreased seed yields 19%. Furrow irrigating at 0.4 bar decreased yields 26% below those obtained with irrigation at 0.5 bar. While overirrigation adversely affected yield, irrigation treatment had only a slight effect on seed weight and vigor

    Faster Approximate String Matching for Short Patterns

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    We study the classical approximate string matching problem, that is, given strings PP and QQ and an error threshold kk, find all ending positions of substrings of QQ whose edit distance to PP is at most kk. Let PP and QQ have lengths mm and nn, respectively. On a standard unit-cost word RAM with word size wlognw \geq \log n we present an algorithm using time O(nkmin(log2mlogn,log2mlogww)+n) O(nk \cdot \min(\frac{\log^2 m}{\log n},\frac{\log^2 m\log w}{w}) + n) When PP is short, namely, m=2o(logn)m = 2^{o(\sqrt{\log n})} or m=2o(w/logw)m = 2^{o(\sqrt{w/\log w})} this improves the previously best known time bounds for the problem. The result is achieved using a novel implementation of the Landau-Vishkin algorithm based on tabulation and word-level parallelism.Comment: To appear in Theory of Computing System
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