4,092 research outputs found
Error bounds for compound quadrature of weakly singular integrals
Prediction of slow convergence rates for weakly singular numerical quadrature
Smoothness of solutions of Volterra integral equations with weakly singular kernels
Solution smoothness of Volterra integral equations with weakly singular kernel
Clementine Sensor Processing System
The design of the DSPSE Satellite Controller (DSC) is baselined as a single-string satellite controller. The DSC performs two main functions: health and maintenance of the spacecraft; and image capture, storage, and playback. The DSC contains two processors: a radiation-hardened Mil-Std-1750, and a commercial R3000. The Mil-Std-1750 processor performs all housekeeping operations, while the R3000 is mainly used to perform the image processing functions associated with the navigation functions, as well as performing various experiments. The DSC also contains a data handling unit (DHU) used to interface to various spacecraft imaging sensors and to capture, compress, and store selected images onto the solid-state data recorder. The development of the DSC evolved from several key requirements; the DSPSE satellite was to do the following: (1) have a radiation-hardened spacecraft control system and be immune to single-event upsets (SEU's); (2) use an R3000-based processor to run the star tracker software that was developed by SDIO (due to schedule and cost constraints, there was no time to port the software to a radiation-hardened processor); and (3) fly a commercial processor to verify its suitability for use in a space environment. In order to enhance the DSC reliability, the system was designed with multiple processing paths. These multiple processing paths provide for greater tolerance to various component failures. The DSC was designed so that all housekeeping processing functions are performed by either the Mil-Std-1750 processor or the R3000 processor. The image capture and storage is performed either by the DHU or the R3000 processor
Discovering Asymmetric Dark Matter with Anti-Neutrinos
We discuss possible signatures of Asymmetric Dark Matter (ADM) through dark
matter decays to neutrinos. We specifically focus on scenarios in which the
Standard Model (SM) baryon asymmetry is transferred to the dark sector (DS)
through higher dimensional operators in chemical equilibrium. In such cases,
the dark matter (DM) carries lepton and/or baryon number, and we point out that
for a wide range of quantum number assignments, by far the strongest
constraints on dark matter decays come from decays to neutrinos through the
"neutrino portal" operator HL. Together with the facts that ADM favors lighter
DM masses ~ a few GeV and that the decays would lead only to anti-neutrinos and
no neutrinos (or vice versa), the detection of such decays at neutrino
telescopes would provide compelling evidence for ADM. We discuss current and
future bounds on models where the DM decays to neutrinos through operators of
dimension <= 6. For dimension 6 operators, the scale suppressing the decay is
bounded to be >~ 10^12 - 10^13 GeV.Comment: 20 pages, 1 figur
System and method for moving a probe to follow movements of tissue
An apparatus is described for moving a probe that engages moving living tissue such as a heart or an artery that is penetrated by the probe, which moves the probe in synchronism with the tissue to maintain the probe at a constant location with respect to the tissue. The apparatus includes a servo positioner which moves a servo member to maintain a constant distance from a sensed object while applying very little force to the sensed object, and a follower having a stirrup at one end resting on a surface of the living tissue and another end carrying a sensed object adjacent to the servo member. A probe holder has one end mounted on the servo member and another end which holds the probe
About the relationship between auroral electrojets and ring currents
International audienceThe relationship between the storm-time ring current and the auroral electrojets is investigated using IMAGE magnetometer data, DSt and H-SYM, and solar wind data. Statistical results as well as the investigation of single events show that the auroral electrojets occur also during nonstorm conditions without storm-time ring current development and even during the storm recovery phase of increasing DSt. A close correlation between electrojet intensity and ring current intensity was not found. Though the eastward electrojet moves equatorward during the storm main phase there is no unequivocal relationship between the movement of the westward electrojet and the ring current development. All these results suggest that the auroral electrojets and the ring current develop more or less independently of each other
The use of ultrasound in clinical setting for children affected by NAFLD. is it safe and accurate?
Non-alcoholic fatty liver disease (NAFLD) has become over the last decade the most common form of chronic liver disease in children and adults. Thus, establishing the diagnosis of NAFLD is of utmost importance and represents a major challenge as the disease is generally silent and the current gold standard for diagnosis is an invasive liver biopsy, a procedure that is not suitable for screening purposes. Many non-invasive diagnostic tools have been evaluated so far. Recently the utility of ultrasonography for non-invasive diagnosis and estimation of hepatic steatosis has been demonstrated in a large prospective pediatric study
The Effective Field Theory of Dark Matter Direct Detection
We extend and explore the general non-relativistic effective theory of dark
matter (DM) direct detection. We describe the basic non-relativistic building
blocks of operators and discuss their symmetry properties, writing down all
Galilean-invariant operators up to quadratic order in momentum transfer arising
from exchange of particles of spin 1 or less. Any DM particle theory can be
translated into the coefficients of an effective operator and any effective
operator can be simply related to most general description of the nuclear
response. We find several operators which lead to novel nuclear responses.
These responses differ significantly from the standard minimal WIMP cases in
their relative coupling strengths to various elements, changing how the results
from different experiments should be compared against each other. Response
functions are evaluated for common DM targets - F, Na, Ge, I, and Xe - using
standard shell model techniques. We point out that each of the nuclear
responses is familiar from past studies of semi-leptonic electroweak
interactions, and thus potentially testable in weak interaction studies. We
provide tables of the full set of required matrix elements at finite momentum
transfer for a range of common elements, making a careful and fully
model-independent analysis possible. Finally, we discuss embedding
non-relativistic effective theory operators into UV models of dark matter.Comment: 32+23 pages, 5 figures; v2: some typos corrected and definitions
clarified; v3: some factors of 4pi correcte
On the new economic philosophy of crisis management in the European Union
This essay attempts to go beyond presenting the bits and pieces of still ongoing crisis management in the EU. Instead it attempts at finding the ‘red thread’ behind a series of politically improvised decisions. Our fundamental research question asks whether basic economic lessons learned in the 1970s are still valid. Namely, that a crises emanating from either structural or regulatory weaknesses cannot and should not be remedied by demand management. Our second research question is the following: Can lacking internal commitment and conviction in any member state be replaced or substituted by external pressure or formalized procedures and sanctions? Under those angles we analyze the project on establishing a fiscal and banking union in the EU, as approved by the Council in December 2012
Assessment of culture and environment in the Adolescent Brain and Cognitive Development Study: Rationale, description of measures, and early data.
Neurodevelopmental maturation takes place in a social environment in addition to a neurobiological one. Characterization of social environmental factors that influence this process is therefore an essential component in developing an accurate model of adolescent brain and neurocognitive development, as well as susceptibility to change with the use of marijuana and other drugs. The creation of the Culture and Environment (CE) measurement component of the ABCD protocol was guided by this understanding. Three areas were identified by the CE Work Group as central to this process: influences relating to CE Group membership, influences created by the proximal social environment, influences stemming from social interactions. Eleven measures assess these influences, and by time of publication, will have been administered to well over 7,000 9-10 year-old children and one of their parents. Our report presents baseline data on psychometric characteristics (mean, standard deviation, range, skewness, coefficient alpha) of all measures within the battery. Effectiveness of the battery in differentiating 9-10 year olds who were classified as at higher and lower risk for marijuana use in adolescence was also evaluated. Psychometric characteristics on all measures were good to excellent; higher vs. lower risk contrasts were significant in areas where risk differentiation would be anticipated
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