598 research outputs found
transition form factor within Light Front Quark Model
We study the transition form factor of as a
function of the momentum transfer within the light-front quark model
(LFQM). We compare our result with the experimental data by BaBar as well as
other calculations based on the LFQM in the literature. We show that our
predicted form factor fits well with the experimental data, particularly those
at the large region.Comment: 11 pages, 4 figures, accepted for publication in PR
Theory Summary and Future Directions
Summary talk at the Lepton-Photon Symposium, Cornell University, Aug. 10-15,
1993.Comment: (Talk presented at the Lepton-Photon Symposium, Cornell University,
Aug. 10-15, 1993.) 19 page
The use of strong personal media in the context of chronic disease treatment : music as a mediator of depression and pain experience
Thesis (Ph. D.)--Harvard-MIT Program in Health Sciences and Technology, 2013.Cataloged from PDF version of thesis.Includes bibliographical references.Introduction: It is postulated that music has been part of society for at least 50,000 years, since the time that humans lived in one location of the world before dispersing across the globe (44). Over the eras it evolved in its manifestation, from classical performances enjoyed only by the elite, to soulful songs sung in the fields, to myriad forms of expression to be used by anyone. Today, its prominence has even evolved into being used as a tool for cognitive therapy, such as for aphasia patients (41), or to heal those who no longer have the ability to move their bodies (40). Given its incredible, seemingly endless potential, it is fruitful to explore new innovations in its usage - with treatment for chronic diseases such as depression, anxiety, and other mental disorders being ideal candidates. These diseases are high in their cost on resources, both human and monetary, and have weighty long-term impacts on patients' lives as well as their families', with depression being the leading cause of disability worldwide according to the World Health Organization (43). Music is positioned as a potent remedy, as its attributes are almost the mirror negative of the effects from chronic disease: it is low cost, pleasurably pervasive, and socially connecting Thus, the intention behind the design of study 1 in this thesis was to create a pilot, self -driven, wellness-enhancing music treatment that could be used as the basis for a future treatment for depression. It was meant to be a relatively brief longitudinal study examining adherence and feasibility for a personal music augmented mindfulness practice in a small group of healthy subjects. From the insights gleaned during this study, it was determined that the choice of strongly emotional, personal music could be potentially powerful in another disease context. In study 2, the design contracted from a longitudinal one to an acute, nuanced observation of enhanced music analgesia during experimental heat pain with healthy subjects. The clinical tool of interest was a proven analgesia boosting conditioning paradigm, which was combined in this study with personal music. Together, the two studies provide a revealing glimpse of humankind's ability to harness the best attributes it can for self-care from a medium it itself created.by Christine L. Hsieh.Ph.D
Long-chain acyl-CoA synthetase isoforms differ in preferences for eicosanoid species and long-chain fatty acids
Because the signaling eicosanoids, epoxyeicosatrienoic acids (EETs) and HETEs, are esterified to membrane phospholipids, we asked which long-chain acyl-CoA synthetase (ACSL) isoforms would activate these molecules and whether the apparent FA substrate preferences of each ACSL isoform might differ depending on whether it was assayed in mammalian cell membranes or as a purified bacterial recombinant protein. We found that all five ACSL isoforms were able to use EETs and HETEs as substrates and showed by LC-MS/MS that ACSLs produce EET-CoAs. We found differences in substrate preference between ACS assays performed in COS7 cell membranes and recombinant purified proteins. Similarly, preferences and Michaelis-Menten kinetics for long-chain FAs were distinctive. Substrate preferences identified for the purified ACSLs did not correspond to those observed in ACSL-deficient mouse models. Taken together, these data support the concept that each ACSL isoform exhibits a distinct substrate preference, but apparent substrate specificities depend upon multiple factors including membrane character, coactivators, inhibitors, protein interactions, and posttranslational modification
Formation and Device Application of Ge Nanowire Heterostructures via Rapid Thermal Annealing
We reviewed the formation of Ge nanowire heterostructure and its field-effect characteristics by a controlled reaction between a single-crystalline Ge nanowire and Ni contact pads using a facile rapid thermal annealing process. Scanning electron microscopy and transmission electron microscopy demonstrated a wide temperature range of 400~500°C to convert the Ge nanowire to a single-crystalline Ni2Ge/Ge/Ni2Ge nanowire heterostructure with atomically sharp interfaces. More importantly, we studied the effect of oxide confinement during the formation of nickel germanides in a Ge nanowire. In contrast to the formation of Ni2Ge/Ge/Ni2Ge nanowire heterostructures, a segment of high-quality epitaxial NiGe was formed between Ni2Ge with the confinement of Al2O3 during annealing. A twisted epitaxial growth mode was observed in both two Ge nanowire heterostructures to accommodate the large lattice mismatch in the NixGe/Ge interface. Moreover, we have demonstrated field-effect transistors using the nickel germanide regions as source/drain contacts to the Ge nanowire channel. Our Ge nanowire transistors have shown a high-performance p-type behavior with a high on/off ratio of 105 and a field-effect hole mobility of 210âcm2/Vs, which showed a significant improvement compared with that from unreacted Ge nanowire transistors
Correlation Effects in Ultracold Two-Dimensional Bose Gases
We study various properties of an ultracold two-dimensional (2D) Bose gas
that are beyond a mean-field description. We first derive the effective
interaction for such a system as realized in current experiments, which
requires the use of an energy dependent -matrix. Using this result, we then
solve the mean-field equation of state of the modified Popov theory, and
compare it with the usual Hartree-Fock theory. We show that even though the
former theory does not suffer from infrared divergences in both the normal and
superfluid phases, there is an unphysical density discontinuity close to the
Berezinskii-Kosterlitz-Thouless transition. We then improve upon the mean-field
description by using a renormalization group approach and show how the density
discontinuity is resolved. The flow equations in two dimensions, in particular,
of the symmetry-broken phase, already contain some unique features pertinent to
the 2D XY model, even though vortices have not been included explicitly. We
also compute various many-body correlators, and show that correlation effects
beyond the Hartree-Fock theory are important already in the normal phase as
criticality is approached. We finally extend our results to the inhomogeneous
case of a trapped Bose gas using the local-density approximation and show that
close to criticality, the renormalization group approach is required for the
accurate determination of the density profile.Comment: 11 pages, 12 figure
Photoproduction and Radiative Decay of Spin 1/2 and 3/2 Pentaquarks
We study photoproduction and radiative decays of pentauqarks paying
particular attention to the differences between spin-1/2 and spin-3/2, positive
and negative parities of pentaquarks. Detailed study of these processes can not
only give crucial information about the spin, but also the parity of
pentaquarks.Comment: 14 pages, 7 figure
Study of Radiative Leptonic D Meson Decays
We study the radiative leptonic meson decays of D^+_{(s)}\to
\l^+\nu_{\l}\gamma (\l=e,\mu,\tau), and D^0\to
\l^+\l^-\gamma () within the light front quark model. In the standard
model, we find that the decay branching ratios of , and
are (), (), and
(), and that of D^0\to\l^+\l^-\gamma (\l=e,\mu) and
are and ,
respectively.Comment: 23 pages, 6 Figures, LaTex file, a reference added, to be published
in Mod. Phys. Lett.
The influence of backward wave transmission on quantitive ultrasonic evaluation using Lamb wave propagation
In view of the various novel quantitative ultrasonic evaluation techniques developed using Lamb wave propagation, the influence of an important related phenomenon, backward transmission, is investigated in this paper. Using the discrete layer theory and a multiple integral transform method, the surface displacement and velocity responses of isotropic plates and cross-ply laminated composite plates due to the Lamb waves excited by parabolic- and piston-type transmitting transducers are evaluated. Analytical expressions for the surface displacement and velocity frequency response functions are developed. Based on this a large volume of calculations is carried out. Through examining the characteristics of the surface displacement and velocity frequency response functions and, especially, the different propagation modesâ contributions to them, the influence of the backward wave transmission related to quantitative ultrasonicnondestructive evaluation applications is discussed and some important conclusions are drawn
Basal and inducible anti-inflammatory epoxygenase activity in endothelial cells
The roles of CYP lipid-metabolizing pathways in endothelial cells are poorly understood. Human endothelial cells expressed CYP2J2 and soluble epoxide hydrolase (sEH) mRNA and protein. The TLR-4 agonist LPS (1 ÎŒg/ml; 24 h) induced CYP2J2 but not sEH mRNA and protein. LCâMS/MS analysis of the stable commonly used human endothelial cell line EA.Hy926 showed active epoxygenase and epoxide hydrolase activity: with arachidonic acid (stable epoxide products 5,6-DHET, and 14,15-DHET), linoleic acid (9,10-EPOME and 12,13-EPOME and their stable epoxide hydrolase products 9,10-DHOME and 12,13-DHOME), docosahexaenoic acid (stable epoxide hydrolase product 19,20-DiHDPA) and eicosapentaenoic acid (stable epoxide hydrolase product 17,18-DHET) being formed. Inhibition of epoxygenases using either SKF525A or MS-PPOH induced TNFα release, but did not affect LPS, IL-1ÎČ, or phorbol-12-myristate-13-acetate (PMA)-induced TNFα release. In contrast, inhibition of soluble epoxide hydrolase by AUDA or TPPU inhibited basal, LPS, IL-1ÎČ and PMA induced TNFα release, and LPS-induced NFÎșB p65 nuclear translocation. In conclusion, human endothelial cells contain a TLR-4 regulated epoxygenase CYP2J2 and metabolize linoleic acid > eicosapentaenoic acid > arachidonic acid > docosahexaenoic acid to products with anti-inflammatory activity
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