19,968 research outputs found
The formation and merger of compact objects in the central engine of active galactic nuclei and quasars: Gamma-ray burst and gravitational radiation
The production rate of compact objects, i.e., neutron stars (NSs) and black holes (BHs), in active galactic nuclei (AGNs) and quasars (QSOs), where frequent supernova explosions are used to explain the high metallicity, is very high because of the interaction between the accretion disk and main-sequence stars in the nucleus of the quasar. The compact object red giant (RG) star binaries can be easily formed because of the large captured cross section of the RG stars. The (NS/BH, NS/BH) binary can be formed after the supernova explosion of the (NS/BH, RG) binary. Intense transient gamma-ray emission (gamma-ray burst) and gravitational radiation can result from the merger of these two compact objects. Collision between the helium core (Hc) of the RG and the BH may also take place and may also result in long-duration gamma-ray bursts but no gravitational waves. We estimate that the merger rate of (NS/BH, NS/BH) binaries and (Hc, BH) is proportional to the metal abundance N v/C IV and can be as high as 10-3 [(N v/C IV)/0.01] yr-1 per AGN/QSO.published_or_final_versio
Flexible coping psychotherapy for functional dyspeptic patients: A randomized, controlled trial
OBJECTIVE: This study tested the efficacy of a new psychotherapy, flexible coping psychotherapy (FCP), specifically designed for enhancing coping flexibility of patients with functional dyspepsia (FD). The design of this psychotherapy is based on the general cognitive-behavioral model and previous findings on FD. METHODS: We adopted a randomized, controlled design to examine the differences between the target (FCP) and control (supportive psychotherapy [SPP]) conditions. Coping flexibility and outcome measures reported by 75 Chinese FD patients (18-65 years; 35% men) were assessed before and 12 months after treatment. RESULTS: Results revealed that participants who received the FCP reported an increase in coping flexibility as well as reductions in self-rated dyspeptic symptom severity (SDSS), gastroenterologist-rated dyspeptic symptom severity, and anxiety levels (p values <.01). Participants who received the SPP reported reductions in SDSS and anxiety levels (p values <.0001). Although both groups reported a decrease in SDSS, only the SDSS level of the FCP group was comparable to that of a healthy community sample (p = .28). CONCLUSIONS: These findings suggest that FCP is a potentially effective intervention for treating FD symptoms. Its effectiveness may be attributable to the specific components of FCP rather than common psychotherapeutic factors such as emotional support and empathy per se. Copyright © 2007 by American Psychosomatic Society.postprin
The One-Loop One-Mass Hexagon Integral in D=6 Dimensions
We evaluate analytically the one-loop one-mass hexagon in six dimensions. The
result is given in terms of standard polylogarithms of uniform transcendental
weight three.Comment: 9 page
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Enabling Thin and Flexible Solid-State Composite Electrolytes by the Scalable Solution Process
All solid-state batteries (ASSBs) have the potential to deliver higher energy densities, wider operating temperature range, and improved safety compared with today's liquid-electrolyte-based batteries. However, of the various solid-state electrolyte (SSE) classes - polymers, sulfides, or oxides - none alone can deliver the combined properties of ionic conductivity, mechanical, and chemical stability needed to address scalability and commercialization challenges. While promising strategies to overcome these include the use of polymer/oxide or sulfide composites, there is still a lack of fundamental understanding between different SSE-polymer-solvent systems and its selection criteria. Here, we isolate various SSE-polymer-solvent systems and study their molecular level interactions by combining various characterization tools. With these findings, we introduce a suitable Li7P3S11SSE-SEBS polymer-xylene solvent combination that significantly reduces SSE thickness (∼50 μm). The SSE-polymer composite displays high room temperature conductivity (0.7 mS cm-1) and good stability with lithium metal by plating and stripping over 2000 h at 1.1 mAh cm-2. This study suggests the importance of understanding fundamental SSE-polymer-solvent interactions and provides a design strategy for scalable production of ASSBs
Missing Momentum Reconstruction and Spin Measurements at Hadron Colliders
We study methods for reconstructing the momenta of invisible particles in
cascade decay chains at hadron colliders. We focus on scenarios, such as SUSY
and UED, in which new physics particles are pair produced. Their subsequent
decays lead to two decay chains ending with neutral stable particles escaping
detection. Assuming that the masses of the decaying particles are already
measured, we obtain the momenta by imposing the mass-shell constraints. Using
this information, we develop techniques of determining spins of particles in
theories beyond the standard model. Unlike the methods relying on Lorentz
invariant variables, this method can be used to determine the spin of the
particle which initiates the decay chain. We present two complementary ways of
applying our method by using more inclusive variables relying on kinematic
information from one decay chain, as well as constructing correlation variables
based on the kinematics of both decay chains in the same event.Comment: Version to appear in JHE
Measuring Invisible Particle Masses Using a Single Short Decay Chain
We consider the mass measurement at hadron colliders for a decay chain of two
steps, which ends with a missing particle. Such a topology appears as a
subprocess of signal events of many new physics models which contain a dark
matter candidate. From the two visible particles coming from the decay chain,
only one invariant mass combination can be formed and hence it is na\"ively
expected that the masses of the three invisible particles in the decay chain
cannot be determined from a single end point of the invariant mass
distribution. We show that the event distribution in the
vs. invariant mass-squared plane, where , are the transverse
energies of the two visible particles, contains the information of all three
invisible particle masses and allows them to be extracted individually. The
experimental smearing and combinatorial issues pose challenges to the mass
measurements. However, in many cases the three invisible particle masses in the
decay chain can be determined with reasonable accuracies.Comment: 45 pages, 32 figure
Age of the Laschamp excursion determined by U-Th dating of a speleothem geomagnetic record from North America
The Laschamp geomagnetic excursion was the first short-lived polarity event recognized and described in the paleomagnetic record, and to date remains the most studied geomagnetic event of its kind. In addition to its geophysical significance, the Laschamp is an important global geochronologic marker. The Laschamp excursion
occurred around the time of the demise of Homo neanderthalensis, in conjunction with high-amplitude, rapid climatic oscillations leading into the Last Glacial Maximum, and coeval with a major supervolcano eruption in the Mediterranean. Thus, precise determination of the timing and duration of the Laschamp excursion would help in elucidating major scientific questions situated at the intersection of geology, paleoclimatology, and anthropology. Here we present a North American speleothem geomagnetic record of the Laschamp excursion that is directly dated using a combination of high-precision 230Th dates and annual layer counting using confocal microscopy. We have determined a maximum excursion duration that spans the interval 42,250-39,700 yr BP, and an age of 41,100 ± 350 yr BP for the main phase of the excursion, during which the virtual geomagnetic pole was situated at the southernmost latitude in the record. Our chronology provides the first age bracketing of the Laschamp excursion using radioisotopic dating, and improves on previous age determinations based on 40Ar/39Ar dating of lava flows, and orbitally-tuned sedimentary and ice-core records.This project was funded by NSF-EAR grant 1316385, a University of Minnesota McKnight Land Grant Professorship to JMF, and ERC grant 320750. Confocal microscopy was performed at the University of Minnesota Imaging Centers. We are grateful to John Geissman, Brad Singer, and James Channell for their constructive reviews. This is Institute for Rock Magnetism contribution 1506.This is the author accepted manuscript. The final version is available from the Geological Society of America via http://dx.doi.org/10.1130/G37490.
Tests of scaling assumputions, construct validity and reliability of the Chinese child health questionnaire, partent form (CHQ-PF50) and child form (CHQ-CF87)
Poster SessionValidated instruments for assessment of quality of life in Chinese children are as yet unavailable. We determined
the construct validity and reliability of the translated Chinese versions of the Child Health Questionnaires (Landgraf,
Abetz & Ware, 1999) designed for completion by parents (CHQ-PF50) and children (CHQ-CF87). The Chinese
versions were developed through iterative forward and backward translation processes by independent parties.
The feasibility, as rated by degree of difficulty using a 4-point scale, and time for completion were evaluated for the
Chinese CHQ-PF50 and CHQ-CF87 in 15 and 11 subjects, respectively. To assess the construct validity and reliability,
1143 parents of healthy children and 823 school children were invited to complete the Chinese CHQ-PF50 and
CHQ-CF87, respectively. The results showed that both the Chinese CHQ-PF50 (mean rating 1.66) and CHQ-CF87
(mean rating 1.33) were easy to complete, with completion times of 14.23±5.23 minutes and 13.82±3.52 minutes,
respectively. Psychometric analysis on item convergent validity and discriminant validity showed perfect or near
perfect (>99%) rates of success for all ten scales in the CF87 and >94% for all but one scale in the PF50. The exception
was the general health scale (86%). Minimal floor effects were observed for both questionnaires. However, substantial
ceiling effects were observed for the five scales in both questionnaires (physical functioning, role-emotional,
behavioral, role-physical, bodily pain and family activities). The median alpha coefficient of reliability for CF87
was 0.90 (range 0.85 to 0.94). The median alpha coefficient for PF50 was 0.80 (range 0.44 to 0.88), with the mental
health scale falling just below the minimum criterion for group level analysis (0.68) and the general health scale
being the lowest (0.44). These findings suggest that the Chinese translations of CHQ-PF50 and CHQ-CF87 are
robust and sufficient. Additional work with regard to ceiling effects is required to assess the performance of the
measures in condition groups
The study of the energy management system based-on fuzzy control for distributed hybrid wind-solar power system
Author name used in this publication: K. W. E. ChengRefereed conference paper2004-2005 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe
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