47,238 research outputs found
Meteoroid detector
A meteoroid detector is described which uses, a cold cathode discharge tube with a gas-pressurized cell in space for recording a meteoroid puncture of the cell and for determining the size of the puncture
On the origin of <i>Halipeurus heraldicus</i> on Round Island petrels: cophylogenetic relationships between petrels and their chewing lice
Lice phylogenetic relationships have often been used to elucidate host relationships and vice versa. In this study, we investigate the louse genus Halipeurus which parasitizes bird hosts in the families Procellariidae, Hydrobatidae and Pelecanoididae. The presence of two lice species on Pterodroma arminjoniana in different breeding grounds (Halipeurus heraldicus on Round Island, off Mauritius in the Indian Ocean and Halipeurus kermadecensis on Trindade Island in the Atlantic Ocean) has led to some confusion in the distribution of Pt. arminjoniana and its close relatives Pt. heraldica and Pt. neglecta. By using a cophylogenetic approach that incorporates uncertainties in phylogenetic reconstructions, we show significant overall coevolution between Halipeurus lice and their hosts. However, the study also indicates that the presence of H. heraldicus on Pt. arminjoniana and Pt. neglecta on Round Island and on Pt. heraldica on Gambier Island are the result of a host switch whereas H. kermadecensis is the ancestral parasite of Pt. arminjoniana. This suggests that H. kermadecensis was lost during or after colonisation of Round Island by Pt. arminjoniana. We conclude that cophylogenetic analyses are central to inferring the evolutionary history and biogeographical patterns of hosts and their parasites
TERMINAL MARKET WINDOWS FOR MISSISSIPPI SMALL-FARM VEGETABLE PRODUCERS
This study investigated various marketing strategies involving market windows at wholesale fruit and vegetable terminal markets. Data used in the analysis included weekly prices for okra, sweet corn, strawberries, and green cabbage at terminal markets located in Dallas, St. Louis, Atlanta, Chicago, Cincinnati, and Detroit. Strawberries showed relatively high profit margins for small farmers operating in southwest Mississippi. Sweet corn and okra showed more narrow profit margins, while green cabbage appeared to yield negative net returns (generally) for these farmers. Furthermore, stochastic dominance analysis of various combinations of crop/market/window revealed the following as the preferred marketing strategies: (1) strawberries in all markets in the last third of the calendar year; (2) sweet corn in all six markets in the first third of the calendar year; and (3) okra in St. Louis and Cincinnati in the first third of the calendar year.Agribusiness,
Recent integral cross section validation measurements at the ASP facility
This work presents new integral data measured at the ASP 14 MeV neutron
irradiation facility at Aldermaston in the UK, which has recently become
available for fusion-related work through the CCFE materials programme.
Measurements of reaction products from activation experiments using elemental
foils were carried out using gamma spectrometry in a high efficiency,
high-purity germanium (HPGe) detector and associated digital signal processing
hardware. Following irradiation and rapid extraction to the measurement cell,
gamma emissions were acquired with both energy and time bins. Integral cross
section and half-life data have been derived from these measurements. Selected
integral cross section values are presented from the measurement campaigns.Comment: 4 pages, 5 figure
Quantum key distribution over 122 km of standard telecom fiber
We report the first demonstration of quantum key distribution over a standard
telecom fiber exceeding 100 km in length. Through careful optimisation of the
interferometer and single photon detector, we achieve a quantum bit error ratio
of 8.9% for a 122km link, allowing a secure shared key to be formed after error
correction and privacy amplification. Key formation rates of up to 1.9 kbit/sec
are achieved depending upon fiber length. We discuss the factors limiting the
maximum fiber length in quantum cryptography
Many-body mobility edge due to symmetry-constrained dynamics and strong interactions
We provide numerical evidence combined with an analytical understanding of
the many-body mobility edge for the strongly anisotropic spin-1/2 XXZ model in
a random magnetic field. The system dynamics can be understood in terms of
symmetry-constrained excitations about parent states with ferromagnetic and
anti-ferromagnetic short range order. These two regimes yield vastly different
dynamics producing an observable, tunable many-body mobility edge. We compute a
set of diagnostic quantities that verify the presence of the mobility edge and
discuss how weakly correlated disorder can tune the mobility edge further.Comment: 10 pages, 5 figure
Family-focused treatment for childhood depression: model and case illustrations
Although the evidence base for treatment of depressive disorders in adolescents has strengthened in recent years, less is known about the treatment of depression in middle to late childhood. A family-based treatment may be optimal in addressing the interpersonal problems and symptoms frequently evident among depressed children during this developmental phase, particularly given data indicating that attributes of the family environment predict recovery versus continuing depression among depressed children. Family-Focused Treatment for Childhood Depression (FFT-CD) is designed as a 15-session family treatment with both the youth and parents targeting two putative mechanisms involved in recovery: (a) enhancing family support, specifically decreasing criticism and increasing supportive interactions; and (b) strengthening specific cognitive-behavioral skills within a family context that have been central to CBT for depression, specifically behavioral activation, communication, and problem solving. This article describes in detail the FFT-CD protocol and illustrates its implementation with three depressed children and their families. Common themes/challenges in treatment included family stressors, comorbidity, parental mental health challenges, and inclusion/integration of siblings into sessions. These three children experienced positive changes from pre- to posttreatment on assessor-rated depressive symptoms, parent- and child-rated depressive symptoms, and parent-rated internalizing and externalizing symptoms. These changes were maintained at follow-up evaluations 4 and 9 months following treatment completion.K23 MH101238 - NIMH NIH HHS; R01 MH082856 - NIMH NIH HHS; R01 MH082861 - NIMH NIH HH
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