436 research outputs found

    A Taxonomic and Ecological Study of Acridinae of Utah (Orthoptera-Locustidae)

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    Orthoptera, especially the family Locustidae, is one of the most important and most interesting orders of insects in the state of Utah. It includes a polyphagus group of great economic importance in the state. The topography and climate of Utah varies from forested alpine slopes to hot arid desert wastes, several life zones being represented. This great variation from desert to alpine in Utah presents a rather unique region for taxonomic and ecological studies of the Orthoptera. The most familiar representatives of the insect order Orthoptera are the long-horned grasshoppers, locusts, crickets, katydids, and cockroaches. Orthoptera are characterized by Comstock as those insects having mouth parts fitted for chewing, gradual metamorphosis, nymphal development terrestrial, with 2 pairs of wings or with wings bestigial or wanting. In winged forms the fore wings are more or less thickened, but have distinct venation; the hing wings, when at rest, are folded in plaits like a fan. The family Locustidae, called Acrididae by many authors, includes the locusts or short-horned grasshoppers, which are characterized by having short antennae, 3-jointed tarsi, and a short ovipositor in the female. The ovipositor has 4 separate spines and an egg guide for ovipositing. The 4 separate spines are used to penetrate the ground to a depth corresponding to the length of the abdomen. The eggs are then placed 1 at a time in regular order by the egg guide. During the process of egg-laying a fluid is secreted which hardens and binds the eggs together into a definite mass. The organs of hearing are situated on the first abdominal segment. There are 4 subfamilies of Locustidae. The Acrydiinae, commonly called pigmy locusts, have the pronotum extending over the entire dorsum of the abdomen; the claws of the tarsi have no arolium between them. The other 3 subfamilies have the pronotum extending, at most, only over the base of the abdomen, and the claws of the tarsi have an arolium between them. The Cyrtacanthacrinae (Locustinae), or spur-throated locusts, have the prosternum armed with a distinct conical tuberole. The Oedipodinae, or banded-winged locusts, lack the prosternal tubercle and have the head rounded at the union of the vertex and front. The Acridinae, commonly called slant-faced locusts, is the subfamily under consideration in this paper. The slant-faced locusts have a low median pronotal carina which is cut by one transverse sulcus; the front and vertex usually meet in an acute angle

    Genomic and non-genomic effects of androgens in the cardiovascular system: clinical implications

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    The principle steroidal androgens are testosterone and its metabolite 5α-dihydrotestosterone (DHT), which is converted from testosterone by the enzyme 5α-reductase. Through the classic pathway with androgens crossing the plasma membrane and binding to the androgen receptor (AR) or via mechanisms independent of the ligand-dependent transactivation function of nuclear receptors, testosterone induces genomic and non-genomic effects respectively. AR is widely distributed in several tissues, including vascular endothelial and smooth muscle cells. Androgens are essential for many developmental and physiological processes, especially in male reproductive tissues. It is now clear that androgens have multiple actions besides sex differentiation and sexual maturation and that many physiological systems are influenced by androgens, including regulation of cardiovascular function [nitric oxide (NO) release, Ca2+ mobilization, vascular apoptosis, hypertrophy, calcification, senescence and reactive oxygen species (ROS) generation]. This review focuses on evidence indicating that interplay between genomic and non-genomic actions of testosterone may influence cardiovascular function

    Two-axis antenna positioning mechanism

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    The two-axis antenna positioning mechanism (TAAPM) is used to position three Ku-band and one C-band spot antennas on the INTELSAT 7 (I-7) spacecraft, which is a commercial telecommunications satellite purchased and operated by INTELSAT, an international consortium. The first I-7 was successfully launched on 22 Oct. 1993 from French Guiana on an Ariane launch vehicle. The TAAPM's on the first I-7 satellite successfully completed their in-orbit functional testing. The TAAPM was an entirely new design for Space Systems/Loral. This paper will describe the spacecraft/system requirements and application of the TAAPM and present the technical findings of TAAPM qualification and protoflight testing

    Optically thick clumps: not the solution to the Wolf-Rayet wind momentum problem?

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    The hot star wind momentum problem η = Mν∞/(L/c)» much greater than 1 is revisited, and it is shown that the conventional belief, that it can be solved by a combination of clumping of the wind and multiple scattering of photons, is not self-consistent for optically thick clumps. Clumping does reduce the mass loss rate M, and hence the momentum supply, required to generate a specified radio emission measure epsilon, while multiple scattering increases the delivery of momentum from a specified stellar luminosity L. However, in the case of thick clumps, when combined the two effects act in opposition rather than in unison since clumping reduces multiple scattering. From basic geometric considerations, it is shown that this reduction in momentum delivery by clumping more than offsets the reduction in momentum required, for a specified ε. Thus the ratio of momentum deliverable to momentum required is maximal for a smooth wind and the momentum problem remains for the thick clump case. In the case of thin clumps, all of the benefit of clumping in reducing η lies in reducing M for a given ε so that extremely small filling factors f ≈ 10-4 are needed. It is also shown that clumping affects the inference of M from radio ε not only by changing the emission measure per unit mass but also by changing the radio optical depth unity radius Rrad, and hence the observed wind volume, at radio wavelengths. In fact, for free-free opacity proportional to αn2, contrary to intuition, Rrad increases with increasing clumpiness

    Single-centre experience of testosterone therapy for boys with hypogonadism

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    Background: Hypogonadism in boys is one of the commonest conditions encountered in paediatric endocrinology. Aims: To study variations in management in a contemporary group of boys at a single specialist centre. Methods: Retrospective review of case records of all boys treated with testosterone at a tertiary endocrine service from 2012 to 2017. Results: Of the 358 boys reviewed for hypogonadism, 46 (13%) were initiated on testosterone therapy at a median age (range) of 14.2 years (12.1, 17.7). Indications for therapy included a functional delay of puberty that was constitutional in 17 (37%) or related to chronic disease in 10 (22%) or organic hypogonadism due to primary gonadal failure in 7 (15%), multiple pituitary hormone deficiency in 6 (13%), and isolated hypogonadotropic hypogonadism in 6 (13%). Of the 46 boys, 40 (89%) were started on intramuscular testosterone, 4 (9%) on oral testosterone, and 1 (2%) on transdermal gel. Of the 19 boys (40%) with organic hypogonadism re­quiring long-term therapy, 12 (63%) had assessment of liver function, 6 (32%) had a haematocrit, and 2 (11%) had a DXA scan in the year of commencing treatment. Conclusions: Testosterone therapy is administered in about 13% of boys reviewed for hypogonadism and its monitoring requires standardisation

    Evolutionary ecology of pipefish brooding structures:embryo survival and growth do not improve with a pouch

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    For animals that reproduce in water, many adaptations in life-history traits such as egg size, parental care, and behaviors that relate to embryo oxygenation are still poorly understood. In pipefishes, seahorses and seadragons, males care for the embryos either in some sort of brood pouch, or attached ventrally to the skin on their belly or tail. Typically, egg size is larger in the brood pouch group and it has been suggested that oxygen supplied via the pouch buffers the developing embryos against hypoxia and as such is an adaptation that has facilitated the evolution of larger eggs. Here, using four pipefish species, we tested whether the presence or absence of brood pouch relates to how male behavior, embryo size, and survival are affected by hypoxia, with normoxia as control. Two of our studied species Entelurus aequoreus and Nerophis ophidion (both having small eggs) have simple ventral attachment of eggs onto the male trunk, and the other two, Syngnathus typhle (large eggs) and S. rostellatus (small eggs), have fully enclosed brood pouches on the tail. Under hypoxia, all species showed lower embryo survival, while species with brood pouches suffered greater embryo mortality compared to pouchless species, irrespective of oxygen treatment. Behaviorally, species without pouches spent more time closer to the surface, possibly to improve oxygenation. Overall, we found no significant benefits of brood pouches in terms of embryo survival and size under hypoxia. Instead, our results suggest negative effects of large egg size, despite the protection of brood pouches

    On the nature of the prototype LBV AG Carinae I. Fundamental parameters during visual minimum phases and changes in the bolometric luminosity during the S-Dor cycle

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    We present a detailed spectroscopic analysis of the luminous blue variable AG Carinae during the last two visual minimum phases of its S-Dor cycle (1985-1990 and 2000-2003). The analysis reveals an overabundance of He, N, and Na, and a depletion of H, C, and O, on the surface of AG Car, indicating the presence of CNO-processed material. Furthermore, the ratio N/O is higher on the stellar surface than in the nebula. We found that the minimum phases of AG Car are not equal to each other, since we derived a noticeable difference between the maximum effective temperature achieved during 1985-1990 (22,800 K) and 2000-2001 (17,000 K). While the wind terminal velocity was 300 km/s in 1985-1990, it was as low as 105 km/s in 2001. The mass-loss rate, however, was lower from 1985-1990 (1.5 x 10^(-5) Msun/yr) than from 2000-2001 (3.7 x 10^(-5) Msun/yr). We found that the wind of AG Car is significantly clumped (f=0.10 - 0.25) and that clumps must be formed deep in the wind. We derived a bolometric luminosity of 1.5 x 10^6 Lsun during both minimum phases which, contrary to the common assumption, decreases to 1.0 x 10^6 Lsun as the star moves towards maximum flux in the V band. Assuming that the decrease in the bolometric luminosity of AG Car is due to the energy used to expand the outer layers of the star (Lamers 1995), we found that the expanding layers contain roughly 0.6 - 2 Msun. Such an amount of mass is an order of magnitude lower than the nebular mass around AG Car, but is comparable to the nebular mass found around lower-luminosity LBVs and to that of the Little Homunculus of Eta Car. If such a large amount of mass is indeed involved in the S Dor-type variability, we speculate that such instability could be a failed Giant Eruption, with several solar masses never becoming unbound from the star.(abridged)Comment: 22 pages, 13 figures, ApJ in press. A high-resolution PDF version is also available at http://www.mpifr-bonn.mpg.de/staff/jgroh/agcar.htm

    The Rachel Carson Letters and the Making of Silent Spring

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    Environment, conservation, green, and kindred movements look back to Rachel Carson’s 1962 book Silent Spring as a milestone. The impact of the book, including on government, industry, and civil society, was immediate and substantial, and has been extensively described; however, the provenance of the book has been less thoroughly examined. Using Carson’s personal correspondence, this paper reveals that the primary source for Carson’s book was the extensive evidence and contacts compiled by two biodynamic farmers, Marjorie Spock and Mary T. Richards, of Long Island, New York. Their evidence was compiled for a suite of legal actions (1957-1960) against the U.S. Government and that contested the aerial spraying of dichlorodiphenyltrichloroethane (DDT). During Rudolf Steiner’s lifetime, Spock and Richards both studied at Steiner’s Goetheanum, the headquarters of Anthroposophy, located in Dornach, Switzerland. Spock and Richards were prominent U.S. anthroposophists, and established a biodynamic farm under the tutelage of the leading biodynamics exponent of the time, Dr. Ehrenfried Pfeiffer. When their property was under threat from a government program of DDT spraying, they brought their case, eventually lost it, in the process spent US$100,000, and compiled the evidence that they then shared with Carson, who used it, and their extensive contacts and the trial transcripts, as the primary input for Silent Spring. Carson attributed to Spock, Richards, and Pfeiffer, no credit whatsoever in her book. As a consequence, the organics movement has not received the recognition, that is its due, as the primary impulse for Silent Spring, and it is, itself, unaware of this provenance
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