1,847 research outputs found

    Detection of Reconnection Signatures in Solar Flares

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    Solar flare forecasting is limited by the current understanding of mechanisms that govern magnetic reconnection, the main physical phenomenon associated with these events. As a result, forecasting relies mainly on climatological correlations to historical events rather than the underlying physics principles. Solar physics models place the neutral point of the reconnection event in the solar corona. Correspondingly, studies of photospheric magnetic fields indicate changes during solar flares—particularly in relation to the field helicity—on the solar surface as a result of the associated magnetic reconnection. This study utilizes data from the Solar Dynamics Observatory (SDO) Helioseismic and Magnetic Imager (HMI) and SpaceWeather HMI Active Region Patches (SHARPs) to analyze full vector-field component data of the photospheric magnetic field during solar flares within a large HMI dataset (May 2010 through September 2019). This analysis is then used to identify and compare trends in the different categories of flare strengths and determine indications of the physical phenomena taking place

    Effects of spatiotemporal resource heterogeneity on home range size of American beaver

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    Home range size of terrestrial animals may be influenced by spatiotemporal dynamics of resources. However, little is known regarding the effects of spatiotemporal resource availability on semi-aquatic central place foragers such as the American beaver Castor canadensis. From January 2011 to April 2012, 26 beavers at 11 wetlands at Redstone Arsenal in north-central Alabama, USA, were captured and radio-tracked using radio telemetry. The objectives of this study were to test the predictions of three hypotheses: (1) the resource dispersion hypothesis: more spatially dispersed resources throughout a landscape increase home range sizes; (2) the temporal resource variability hypothesis: more temporally variable resources result in decreases in home range sizes; (3) the habitat productivity hypothesis: increases in habitat productivity lead to decreases in home range sizes. Twenty-three of 26 radio-tagged beavers had well-bounded home ranges, and their home range sizes were positively related to the diversity of land cover within home ranges as predicted by the resource dispersion hypothesis. Furthermore, home range sizes of 26 beavers, including three seasonally dispersing beavers, decreased with increasing seasonal variability of within-home-range normalized difference vegetation index (NDVI), supporting the prediction of the resource heterogeneity hypothesis. Home range sizes of American beavers increased with increasing total NDVI and proportions of woody plant cover within home ranges probably to avoid overexploitation of woody plants. Our results suggest that the combination of resource quantity, spatial distribution and seasonal variation of resources influences movements and home ranges of central place foragers

    Effects of spatiotemporal resource heterogeneity on home range size of American beaver

    Get PDF
    Home range size of terrestrial animals may be influenced by spatiotemporal dynamics of resources. However, little is known regarding the effects of spatiotemporal resource availability on semi-aquatic central place foragers such as the American beaver Castor canadensis. From January 2011 to April 2012, 26 beavers at 11 wetlands at Redstone Arsenal in north-central Alabama, USA, were captured and radio-tracked using radio telemetry. The objectives of this study were to test the predictions of three hypotheses: (1) the resource dispersion hypothesis: more spatially dispersed resources throughout a landscape increase home range sizes; (2) the temporal resource variability hypothesis: more temporally variable resources result in decreases in home range sizes; (3) the habitat productivity hypothesis: increases in habitat productivity lead to decreases in home range sizes. Twenty-three of 26 radio-tagged beavers had well-bounded home ranges, and their home range sizes were positively related to the diversity of land cover within home ranges as predicted by the resource dispersion hypothesis. Furthermore, home range sizes of 26 beavers, including three seasonally dispersing beavers, decreased with increasing seasonal variability of within-home-range normalized difference vegetation index (NDVI), supporting the prediction of the resource heterogeneity hypothesis. Home range sizes of American beavers increased with increasing total NDVI and proportions of woody plant cover within home ranges probably to avoid overexploitation of woody plants. Our results suggest that the combination of resource quantity, spatial distribution and seasonal variation of resources influences movements and home ranges of central place foragers

    Mitochondrial DNA Variation among \u3ci\u3eMuscidifurax\u3c/i\u3e spp. (Hymenoptera: Pteromalidae), Pupal Parasitoids of Filth Flies (Diptera)

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    Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing analyses were used to characterize an amplicon of ~625 bp in 4 of the 5 nominate species of Muscidifurax Girault & Sanders, pupal parasitoids of muscoid flies. A single polymorphic nucleotide site was observed among 2 samples of M. raptor Girault & Sanders. No sequence variation was observed among 3 samples of M. raptorellus Kogan & Legner. The sequence of M. uniraptor Kogan & Legner was identical to that of M. raptorellus. Nucleotide divergence among the Muscidifurax spp. ranged from 0.14 to 0.18 substitutions per nucleotide. Muscidifurax zaraptor Kogan & Legner exhibited multiple haplotypes, 2 of which were characterized by sequencing and 4 others by PCR-RFLP. The sequenced haplotypes differed by 0.08 nucleotide substitutions per site. Restriction site analysis indicated that nucleotide divergence ranged from 0.03 to 0.10 among all 6 haplotypes. Analysis of progeny from individual females indicated that the observed variation in M. zaraptor was caused by multiple haplotypes within individuals rather than differentiation among individuals. These results bring to question the specific status of M. uniraptor and indicate that the genus is native to the Western Hemisphere, and not introduced with their primary host, Musca domestica L, as previously proposed. Heteroplasmy and translocation of aportion of the mitochondrial genome to the nuclear genome are discussed as possible causes for the variation observed in M. zaraptor

    Susceptibility of House Fly (Diptera: Muscidae) Larvae to Entomopathogenic Nematodes (Rhabditida: Heterorhabditidae, Steinernematidae)

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    The potential for entomopathogenic nematodes to control flies in cattle feedlots was determined by screening 40 strains representing 8 species of Heterorhabditis Poinar and 5 species of Steinemema Travassos for virulence toward 3rd-instar house flies (maggots), Musca domestica L. None of the 22 strains of Heterorhabditis infecting maggots caused significant levels of mortality in a filter paper assay. Ten strains of Steinemema infected maggots, of which 7 strains (4 S. carpocapsae (Weiser), 2 S.feltiae (Filipjev), and 1 S. scapterisci Nguyen & Smart) caused significant mortality. Ten Heterorhabditis strains and 10 Steinemema strains successfully reproduced for ≥ 2 generations in maggots. No difference was observed between 72-h survival of maggots and adult emergence. Six strains of Steinemema were selected for 10 generations on maggots and then compared with unselected lines. No difference in pathogenicity between selected and unselected lines was observed. Two strains of S. feltiae, SN and UNK-36, and 2 of the best Heterorhabditis strains, H. bacteriophora Poinar OSWEGO and H. megidis Poinar, Jackson & Klein HF -85 were tested in a fresh bovine manure substrate. All 4 strains produced significant fly mortality in the manure substrate, although the S. feltiae strains had significantly lower LC50 values than did the Heterorhabditis spp. The most promising strain, S. feltiae SN, gave LC50 and LC99 values of 4 and 82 infective juveniles per maggot, respectively. These doses were equivalent to 2.7 and 55 infective juveniles per gram of manure and 5.1 and 104 infective juveniles per square centimeter of surface area. Infective juveniles capable of infecting greater wax moth larvae, Galleria mellonella (L.), survived in manure for up to 10 wk without hosts

    Modeling the Physical Structure of the Low Density Pre-protostellar Core Lynds 1498

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    Lynds 1498 is a pre-protostellar core (PPC) and was one of the initial objects toward which molecular depletion and differentiation was detected. Despite the considerable scrutiny of L1498, there has not been a extensive study of the density and temperature structure as derived from radiative transfer modeling of dust continuum observations. We present deep SCUBA observations of L1498 at 850 and 450 micron, high resolution BEARS maps of the N2H+ 1-0 transition, CSO observations of the N2H+ 3-2 transition, and GBT observations of the C3S 4-3 transition. We also present a comparison of derived properties between L1498 and nearby PPCs that have been observed at far-infrared and submillimeter wavelengths. We present a more realistic treatment of PPC heating which varies the strength of the ISRF, Sisrf, and includes attenuation of the ISRF due to dust grains at the outer radius of the core, Av. The best-fitted model consists of a Bonner-Ebert sphere with a central density of 1 - 3 x 10^4 cm-3, R_o ~ 0.29 pc, 0.5 <= Sisrf <= 1, Av ~ 1 mag, and a nearly isothermal temperature profile of ~ 10.5 K for OH8 opacities. C3S emission shows a central depletion hole while N2H+ emission is centrally peaked. The observed depletions of C3S and H2CO, the modest N2H+ abundance, and a central density that is an order of magnitude lower than other modeled PPCs suggests that L1498 may be a forming PPC. Our derived temperature and density profile will improve modeling of molecular line observations that will explicate the core's kinematical and chemical state. (abridged)Comment: 26 pages, 10 figures (2 color figs). Accepted to Ap

    Family coordination in families who have a child with autism spectrum disorder

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    Little is known about the interactions of families where there is a child with autism spectrum disorder (ASD). The present study applies the Lausanne Trilogue Play (LTP) to explore both its applicability to this population as well as to assess resources and areas of deficit in these families. The sample consisted of 68 families with a child with ASD, and 43 families with a typically developing (TD) child. With respect to the global score for family coordination there were several negative correlations: the more severe the symptoms (based on the child’s ADOS score), the more family coordination was dysfunctional. This correlation was particularly high when parents had to play together with the child. In the parts in which only one of the parents played actively with the child, while the other was simply present, some families did achieve scores in the functional range, despite the child’s symptom severity. The outcomes are discussed in terms of their clinical implications both for assessment and for interventio

    Isolation of a wide range of minerals from a thermally treated plant: Equisetum arvense, a Mare’s tale

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    Silica is the second most abundant biomineral being exceeded in nature only by biogenic CaCO3. Many land plants (such as rice, cereals, cucumber, etc.) deposit silica in significant amounts to reinforce their tissues and as a systematic response to pathogen attack. One of the most ancient species of living vascular plants, Equisetum arvense is also able to take up and accumulate silica in all parts of the plant. Numerous methods have been developed for elimination of the organic material and/or metal ions present in plant material to isolate biogenic silica. However, depending on the chemical and/or physical treatment applied to branch or stem from Equisetum arvense; other mineral forms such glass-type materials (i.e. CaSiO3), salts (i.e. KCl) or luminescent materials can also be isolated from the plant material. In the current contribution, we show the chemical and/or thermal routes that lead to the formation of a number of different mineral types in addition to biogenic silica

    Measurement of the WW Boson Mass

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    A measurement of the mass of the WW boson is presented based on a sample of 5982 WeνW \rightarrow e \nu decays observed in ppp\overline{p} collisions at s\sqrt{s} = 1.8~TeV with the D\O\ detector during the 1992--1993 run. From a fit to the transverse mass spectrum, combined with measurements of the ZZ boson mass, the WW boson mass is measured to be MW=80.350±0.140(stat.)±0.165(syst.)±0.160(scale)GeV/c2M_W = 80.350 \pm 0.140 (stat.) \pm 0.165 (syst.) \pm 0.160 (scale) GeV/c^2.Comment: 12 pages, LaTex, style Revtex, including 3 postscript figures (submitted to PRL
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