3,830 research outputs found

    Nondestructive assessment of penetration of electron-beam welds

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    Empirical method correlates penetration of an electron-beam weld with external measurements of the weld. Empirical polygon accurately confirms full-penetration welds while a second, larger polygon provides for penetration of welds near the tip

    Mating behavior and reproductive morphology predict macroevolution of sex allocation in hermaphroditic flatworms

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    Background:Sex allocation is the distribution of resources to male or female reproduction. In hermaphrodites, this concerns an individual’s resource allocation to, for example, the production of male or female gametes. Macroevolutionary studies across hermaphroditic plants have revealed that the self-pollination rate and the pollination mode are strong predictors of sex allocation. Consequently, we expect similar factors such as the selfing rate and aspects of the reproductive biology, like the mating behaviour and the intensity of postcopulatory sexual selection, to predict sex allocation in hermaphroditic animals. However, comparative work on hermaphroditic animals is limited. Here, we study sex allocation in 120 species of the hermaphroditic free-living flatworm genus Macrostomum. We ask how hypodermic insemination, a convergently evolved mating behaviour where sperm are traumatically injected through the partner’s epidermis, affects the evolution of sex allocation. We also test the commonly-made assumption that investment into male and female reproduction should trade-off. Finally, we ask if morphological indicators of the intensity of postcopulatory sexual selection (female genital complexity, male copulatory organ length, and sperm length) can predict sex allocation.Results:We find that the repeated evolution of hypodermic insemination predicts a more female-biased sex allocation (i.e., a relative shift towards female allocation). Moreover, transcriptome-based estimates of heterozygosity reveal reduced heterozygosity in hypodermically mating species, indicating that this mating behavior is linked to increased selfing or biparental inbreeding. Therefore, hypodermic insemination could represent a selfing syndrome. Furthermore, across the genus, allocation to male and female gametes is negatively related, and larger species have a more female-biased sex allocation. Finally, increased female genital complexity, longer sperm, and a longer male copulatory organ predict a more male-biased sex allocation.Conclusions:Selfing syndromes have repeatedly originated in plants. Remarkably, this macroevolutionary pattern is replicated in Macrostomum flatworms and linked to repeated shifts in reproductive behavior. We also find a trade-off between male and female reproduction, a fundamental assumption of most theories of sex allocation. Beyond that, no theory predicts a more female-biased allocation in larger species, suggesting avenues for future work. Finally, morphological indicators of more intense postcopulatory sexual selection appear to predict more intense sperm competition

    Alternating magnetic anisotropy of Li2_2(Li1−xTx_{1-x}T_x)N with TT = Mn, Fe, Co, and Ni

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    Substantial amounts of the transition metals Mn, Fe, Co, and Ni can be substituted for Li in single crystalline Li2_2(Li1−xTx_{1-x}T_x)N. Isothermal and temperature-dependent magnetization measurements reveal local magnetic moments with magnitudes significantly exceeding the spin-only value. The additional contributions stem from unquenched orbital moments that lead to rare-earth-like behavior of the magnetic properties. Accordingly, extremely large magnetic anisotropies have been found. Most notably, the magnetic anisotropy alternates as easy-plane →\rightarrow easy-axis →\rightarrow easy-plane →\rightarrow easy-axis when progressing from TT = Mn →\rightarrow Fe →\rightarrow Co →\rightarrow Ni. This behavior can be understood based on a perturbation approach in an analytical, single-ion model. The calculated magnetic anisotropies show a surprisingly good agreement with the experiment and capture the basic features observed for the different transition metals.Comment: 5 pages, 3 figures, published as PRB Rapid Communication, Fig. 3 update

    Physiological Impact of Ergot Alkaloid Consumption in Ruminant Livestock

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    Ergot alkaloids in feeds and forages are a worldwide concern. Consumption of ergot alkaloids by ruminant livestock can range from extreme cases that threaten the life of the animal to more frequent and chronic outcomes where livestock productivity is decreased. Consumption of ergot alkaloids alters ruminant physiology such that it outwardly manifests in lower animal intake and gain, decreased reproductive efficiency, and a compromised circulatory system. This talk will cover current research that is improving our understanding of how ergot alkaloids alter cell and tissue physiology that results in the compromised growth and reproduction observed at the whole animal level

    Gamma-Ray Observations of GRO J1655-40

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    The bright transient X-ray source GRO J1655-40 = XN Sco 1994 was observed by the OSSE instrument on the Compton Gamma Ray Observatory (GRO). Preliminary results are reported here. The initial outburst from GRO J1655-40 was detected by BATSE on 27 Jul 1994. OSSE observations were made in five separate viewing periods starting between 4 Aug 1994 and 4 Apr 1995. The first, third, and fifth observations are near the peak luminosity. In the second observation, the source flux had dropped by several orders of magnitude and we can only set an upper limit. The fourth observation is a weak detection after the period of maximum outburst. In contrast with other X-ray novae such as GRO J0422+32, the spectrum determined by OSSE is consistent with a simple power law over the full range of detection, about 50 - 600 keV. The photon spectral index is in the range of -2.5 to 2.8 in all of the observations. We set an upper limit on fractional rms variation \u3c5% in the frequency range 0.01 – 60 Hz. No significant narrow or broad line features are observed at any energy

    The remote scientist

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87390/2/877_1.pd

    Letter from L. H. Boothe

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    Letter concerning the college choir at Utah Agricultural College

    Transfer of fatty acids across the swine uterus and placenta

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    The transfer across the swine uterus and placenta of [1-14C] octanoic acid, [9,10(n)- H] palmitic acid, and [1- 14C] linoleic acid was studied in five gilts and their fetuses during late gestation, following a single bolus injection. Only trace amounts of labeled fatty acids were found in fetal plasma lipid. There were no measureable differences in free fatty acids (FFA) from umbilical artery, and veinous blood. Concentration of FFA in fetal blood was about 40% of the level of uterine values (187, 194, 73, and 82 µEg/1 for uterine artery, uterine vein, umbilical artery, and umbilical vein). In addition, fetal plasma contained larger amounts of 14:0, 16:1, 18:1, and 20:4, whereas maternal plasma contained larger amounts of 18:0 and 18:2. These results indicate that only trace amounts of FFA cross the swine utero-placental unit during late gestation, which are probably not enough to increase energy supply or lipid storage of the fetus.; Swine Day, Manhattan, KS, November 21, 198
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