338 research outputs found
Analytic solution of the Schrodinger equation for an electron in the field of a molecule with an electric dipole moment
We relax the usual diagonal constraint on the matrix representation of the
eigenvalue wave equation by allowing it to be tridiagonal. This results in a
larger solution space that incorporates an exact analytic solution for the
non-central electric dipole potential cos(theta)/r^2, which was known not to
belong to the class of exactly solvable potentials. As a result, we were able
to obtain an exact analytic solution of the three-dimensional time-independent
Schrodinger equation for a charged particle in the field of a point electric
dipole that could carry a nonzero net charge. This problem models the
interaction of an electron with a molecule (neutral or ionized) that has a
permanent electric dipole moment. The solution is written as a series of square
integrable functions that support a tridiagonal matrix representation for the
angular and radial components of the wave operator. Moreover, this solution is
for all energies, the discrete (for bound states) as well as the continuous
(for scattering states). The expansion coefficients of the radial and angular
components of the wavefunction are written in terms of orthogonal polynomials
satisfying three-term recursion relations. For the Coulomb-free case, where the
molecule is neutral, we calculate critical values for its dipole moment below
which no electron capture is allowed. These critical values are obtained not
only for the ground state, where it agrees with already known results, but also
for excited states as well.Comment: 20 pages, 1 figure, 4 table
Expression of cannabinoid receptors in human osteoarthritic cartilage: implications for future therapies
Introduction: Cannabinoids have shown to reduce joint damage in animal models of arthritis and reduce matrix
metalloproteinase expression in primary human steoarthritic (OA) chondrocytes. The actions of cannabinoids are mediated by a number of receptors, including cannabinoid receptors 1 and 2 (CB1 and CB2), Gprotein-coupled receptors 55 and 18 (GPR55 and GPR18), transient receptor potential vanilloid-1 (TRPV1), and peroxisome proliferator-activated receptors alpha and gamma (PPARa and PPARc). However, to date very few studies have investigated the expression and localization of these receptors in human chondrocytes, and expression during degeneration, and thus their potential in clinical applications is unknown.
Methods: Human articular cartilage from patients with symptomatic OA was graded histologically and the expression
and localization of cannabinoid receptors within OA cartilage and underlying bone were determined
immunohistochemically. Expression levels across regions of cartilage and changes with degeneration were investigated.
Results: Expression of all the cannabinoid receptors investigated was observed with no change with grade of
degeneration seen in the expression of CB1, CB2, GPR55, PPARa, and PPARc. Conversely, the number of chondrocytes
within the deep zone of cartilage displaying immunopositivity for GPR18 and TRPV1 was significantly
decreased in degenerate cartilage. Receptor expression was higher in chondrocytes than in osteocytes in the
underlying bone.
Conclusions: Chondrocytes from OA joints were shown to express a wide range of cannabinoid receptors even
in degenerate tissues, demonstrating that these cells could respond to cannabinoids. Cannabinoids designed to
bind to receptors inhibiting the catabolic and pain pathways within the arthritic joint, while avoiding psychoactive effects, could provide potential arthritis therapies.
Key words: articular cartilage; cannabinoid receptors; cannabinoids; osteoarthriti
Virtual Reality in Palliative Care: A Systematic Review
Background: Virtual reality (VR) using head-mounted displays (HMDs) has demonstrated to be an effective tool for treating various somatic and psychological symptoms. Technological advances and increased affordability of VR technology provide an interesting option for delivering psychological interventions to patients in palliative care. The primary aim of this systematic review was to synthesise the available research on the use of VR for enhancing psychological and somatic outcomes for palliative care patients. Secondary aims included assessing general satisfaction and overall usability. Method: A pre-registered systematic literature search was conducted according to PRISMA guidelines using OVID Emcare, Cochrane Library, Embase, Medline, PsycINFO, and PubMed Care Search: Palliative Care Knowledge Network. Peer-reviewed experimental, quasiexperimental, observational, case, and feasibility studies consisting of single or multiple VR sessions using HMDs that reported psychological and/or somatic outcomes were included. Results: Eight studies published between 2019 and 2021 were included, representing 138 patients. While the reported quantitative psychological and somatic outcomes were ambiguous, the qualitative outcomes were largely positive. Participants were generally satisfied with VR, and most studies reported the VR interventions as usable, feasible, and acceptable. Conclusions: VR shows promise in palliative care and generally addresses a range of symptoms with few adverse effects. Future research should consist of adequately powered RCTs evaluating dosage and focusing on providing meaningful activities to enhance outcomes further.Jessica L. Martin, Dimitrios Saredakis, Amanda D. Hutchinson, Gregory B. Crawford, and Tobias Loetsche
The Geminga Fraction
Radio-quiet gamma-ray pulsars like Geminga may account for a number of the unidentified EGRET sources in the Galaxy. The number of Geminga-like pulsars is very sensitive to the geometry of both the gamma-ray and radio beams. Recent studies of the shape and polarization of pulse profiles of young radio pulsars have provided evidence that their radio emission originates in wide cone beams at altitudes that are a significant fraction (1 -10%) of their light cylinder radius. Such wide radio emission beams will be visible at a much larger range of observer angles than the narrow core components thought to originate at lower altitude. Using 3D geometrical modeling that includes relativistic effects from pulsar rotation, we study the visibility of such radio cone beams as well as that of the gamma-ray beams predicted by slot gap and outer gap models. From the results of this study one can obtain revised predictions for the fraction of Geminga-like, radio quiet pulsars present in the gamma-ray pulsar population
ASEAN and the Dynamics of Resistance to Sovereignty Violation:The Case of the Third Indochina War (1978–1991)
This article investigates the history of ASEAN’s relationship to external intervention in regional affairs. It addresses a specific question: What was the basic cause of the success of ASEAN resistance to the Vietnamese challenge to ASEAN’s sovereignty from 1978-1991? ASEAN’s history is understood in terms of a realist theoretical logic, in terms of the relationship between an ASEAN state with the most compelling interests at stake in a given issue, which I call a ‘vanguard state,’ and selected external powers. Using the Third Indochina War (1978–1991) as a case study, this article contends that ASEAN’s ability to resist violations to the sovereignty of Thailand from a Soviet-backed Vietnam is a consequence of high interest convergence between Thailand, and a designated external power, China
Measurement of the Ratio of the Vector to Pseudoscalar Charm Semileptonic Decay Rate \Gamma(D+ > ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)
Using a high statistics sample of photo-produced charm particles from the
FOCUS experiment at Fermilab, we report on the measurement of the ratio of
semileptonic rates \Gamma(D+ > ANTI-K pi mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)=
0.625 +/- 0.045 +/- 0.034. Allowing for the K pi S-wave interference measured
previously by FOCUS, we extract the vector to pseudoscalar ratio \Gamma(D+ >
ANTI-K*0 mu+ nu)/\Gamma(D+ > ANTI-K0 mu+ nu)= 0.594 +/- 0.043 +/- 0.033 and the
ratio \Gamma(D+ > ANTI-K0 mu+ nu)/\Gamma(D+ > K- pi+ pi+)= 1.019 +/- 0.076 +/-
0.065. Our results show a lower ratio for \Gamma(D > K* \ell nu})/\Gamma(D > K
\ell nu) than has been reported recently and indicate the current world average
branching fractions for the decays D+ >ANTI-K0(mu+, e+) nu are low. Using the
PDG world average for B(D+ > K- pi+ pi+) we extract B(D+ > ANIT-K0 mu+
nu)=(9.27 +/- 0.69 +/- 0.59 +/- 0.61)%.Comment: 15 pages, 1 figur
Search for the 1/2+ intruder state in P 35
The excitation energy of deformed intruder states (specifically the 2p2h bandhead) as a function of proton number Z along N=20 is of interest both in terms of better understanding the evolution of nuclear structure between spherical Ca40 and the Island of Inversion nuclei, and for benchmarking theoretical descriptions in this region. At the center of the N=20 Island of Inversion, the npnh (where n=2,4,6) neutron excitations across a diminished N=20 gap result in deformed and collective ground states, as observed in Mg32. In heavier isotones, npnh excitations do not dominate in the ground states but are present in the relatively low-lying level schemes. With the aim of identifying the expected 2p2h - s1/2+ state in P35, the only N=20 isotone for which the neutron 2p2h excitation bandhead has not yet been identified, the S36(d,He3)P35 reaction has been revisited in inverse kinematics with the HELical Orbit Spectrometer (HELIOS) at the Argonne Tandem Linac Accelerator System (ATLAS). While a candidate state has not been located, an upper limit for the transfer reaction cross section to populate such a configuration within a 2.5 to 3.6 MeV energy range provides a stringent constraint on the wave function compositions in both S36 and P35
Demonstration of the temporal matter-wave Talbot effect for trapped matter waves
We demonstrate the temporal Talbot effect for trapped matter waves using
ultracold atoms in an optical lattice. We investigate the phase evolution of an
array of essentially non-interacting matter waves and observe matter-wave
collapse and revival in the form of a Talbot interference pattern. By using
long expansion times, we image momentum space with sub-recoil resolution,
allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure
Longitudinal double-spin asymmetry and cross section for inclusive neutral pion production at midrapidity in polarized proton collisions at sqrt(s) = 200 GeV
We report a measurement of the longitudinal double-spin asymmetry A_LL and
the differential cross section for inclusive Pi0 production at midrapidity in
polarized proton collisions at sqrt(s) = 200 GeV. The cross section was
measured over a transverse momentum range of 1 < p_T < 17 GeV/c and found to be
in good agreement with a next-to-leading order perturbative QCD calculation.
The longitudinal double-spin asymmetry was measured in the range of 3.7 < p_T <
11 GeV/c and excludes a maximal positive gluon polarization in the proton. The
mean transverse momentum fraction of Pi0's in their parent jets was found to be
around 0.7 for electromagnetically triggered events.Comment: 6 pages, 3 figures, submitted to Phys. Rev. D (RC
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