The Relativistic N-body Problem in a Separable Two-Body Basis

We use Dirac's constraint dynamics to obtain a Hamiltonian formulation of the relativistic N-body problem in a separable two-body basis in which the particles interact pair-wise through scalar and vector interactions. The resultant N-body Hamiltonian is relativistically covariant. It can be easily separated in terms of the center-of-mass and the relative motion of any two-body subsystem. It can also be separated into an unperturbed Hamiltonian with a residual interaction. In a system of two-body composite particles, the solutions of the unperturbed Hamiltonian are relativistic two-body internal states, each of which can be obtained by solving a relativistic Schr\"odinger-like equation. The resultant two-body wave functions can be used as basis states to evaluate reaction matrix elements in the general N-body problem. We prove a relativistic version of the post-prior equivalence which guarantees a unique evaluation of the reaction matrix element, independent of the ways of separating the Hamiltonian into unperturbed and residual interactions. Since an arbitrary reaction matrix element involves composite particles in motion, we show explicitly how such matrix elements can be evaluated in terms of the wave functions of the composite particles and the relevant Lorentz transformations.Comment: 42 pages, 2 figures, in LaTe

Estimating the nuclear level density with the Monte Carlo shell model

A method for making realistic estimates of the density of levels in even-even nuclei is presented making use of the Monte Carlo shell model (MCSM). The procedure follows three basic steps: (1) computation of the thermal energy with the MCSM, (2) evaluation of the partition function by integrating the thermal energy, and (3) evaluating the level density by performing the inverse Laplace transform of the partition function using Maximum Entropy reconstruction techniques. It is found that results obtained with schematic interactions, which do not have a sign problem in the MCSM, compare well with realistic shell-model interactions provided an important isospin dependence is accounted for.Comment: 14 pages, 3 postscript figures. Latex with RevTex. Submitted as a rapid communication to Phys. Rev.

Elastic electron deuteron scattering with consistent meson exchange and relativistic contributions of leading order

The influence of relativistic contributions to elastic electron deuteron scattering is studied systematically at low and intermediate momentum transfers ($Q^2\leq 30$ fm$^{-2}$). In a $(p/M)$-expansion, all leading order relativistic $\pi$-exchange contributions consistent with the Bonn OBEPQ models are included. In addition, static heavy meson exchange currents including boost terms and lowest order $\rho\pi\gamma$-currents are considered. Sizeable effects from the various relativistic two-body contributions, mainly from $\pi$-exchange, have been found in form factors, structure functions and the tensor polarization $T_{20}$. Furthermore, static properties, viz. magnetic dipole and charge quadrupole moments and the mean square charge radius are evaluated.Comment: 15 pages Latex including 5 figures, final version accepted for publication in Phys.Rev.C Details of changes: (i) The notation of the curves in Figs. 1 and 2 have been clarified with respect to left and right panels. (ii) In Figs. 3 and 4 an experimental point for T_20 has been added and a corresponding reference [48] (iii) At the end of the text we have added a paragraph concerning the quality of the Bonn OBEPQ potential

Neonatal presentation of ventricular tachycardia and a Reye-like syndrome episode associated with disturbed mitochondrial energy metabolism

BACKGROUND: Hyperammonemia, hypoglycemia, hepatopathy, and ventricular tachycardia are common presenting features of carnitine-acylcarnitine translocase deficiency (Mendelian Inheritance in Man database: *212138), a mitochondrial fatty acid oxidation disorder with a lethal prognosis. These features have not been identified as the presenting features of mitochondrial cytopathy in the neonatal period. CASE PRESENTATION: We describe an atypical presentation of mitochondrial cytopathy in a 2 day-old neonate. She presented with a Reye-like syndrome episode, premature ventricular contractions and ventricular tachycardia. Initial laboratory evaluation exhibited a large amount of 3-methylglutaconic acid on urine organic acid analysis, mild orotic aciduria and a nonspecific abnormal acylcarnitine profile. The evaluation for carnitine-acylcarnitine translocase deficiency and other fatty acid oxidation disorders was negative. The patient later developed a hypertrophic cardiomyopathy and continued to be affected by recurrent Reye-like syndrome episodes triggered by infections. A muscle biopsy exhibited signs of a mitochondrial cytopathy. During the course of her disease, her Reye-like syndrome episodes have subsided; however, cardiomyopathy has persisted along with fatigue and exercise intolerance. CONCLUSIONS: This case illustrates that, in the neonatal period, hyperammonemia and ventricular tachycardia may be the presenting features of a lethal carnitine-acylcarnitine translocase deficiency or of a mitochondrial cytopathy, associated with a milder clinical course. This association broadens the spectrum of presenting phenotypes observed in patients with disturbed mitochondrial energy metabolism. Also, the presence of 3-methylglutaconic aciduria suggests mitochondrial dysfunction and mild orotic aciduria could potentially be used as a marker of mitochondrial disease

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

The deuteron: structure and form factors

A brief review of the history of the discovery of the deuteron in provided. The current status of both experiment and theory for the elastic electron scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic

Interprofessional education—situations of a university in Hong Kong and major hurdles to teachers and students

Studies have provided evidence that Interprofessional Education (IPE) can improve learners’ attitudes, knowledge, skills, behaviors, and competency. Traditionally, IPE is commonly seen in the healthcare professional training in tertiary education. Aging is a global issue that requires more than just a single healthcare sector. It requires interdisciplinary collaboration and understanding to tackle the issues. Therefore, IPE is essential for nurturing university students to tackle the ever-changing global challenges. In addition, different hurdles can hinder IPE development. To have a better understanding of the feasibility, acceptance, and educational value of IPE in Hong Kong, we conducted a cross-sectional quantitative study. We invited teachers and students from a Hong Kong university to fill in an online survey that evaluated their understanding and participation in IPE, their attitude toward IPE, and the barriers to developing IPE from March to June 2020. Among the 37 academic staff and 572 students who completed the survey, 20 (54.1%) teachers and 422 (73.8%) students had never heard of IPE before, and 26 (70.3%) teachers and 510 (89.2%) students had never participated in any IPE activities. Major barriers reported by teachers included an increase in teaching load (72.9%), lack of administrative support (72.9%), lack of financial support and limited budget (67.5%), difficulty to make logistic arrangements (64.8%), and problems with academic schedules and calendars (62.1%). The survey findings revealed that despite the positive attitude of university teachers and students toward IPE, barriers that could hinder the development of IPE included heavy teaching and administrative load and logistic arrangement for classroom arrangement and academic scheduling involving multiple faculties

Anti-cancer effects and mechanism of actions of aspirin analogues in the treatment of glioma cancer

INTRODUCTION: In the past 25 years only modest advancements in glioma treatment have been made, with patient prognosis and median survival time following diagnosis only increasing from 3 to 7 months. A substantial body of clinical and preclinical evidence has suggested a role for aspirin in the treatment of cancer with multiple mechanisms of action proposed including COX 2 inhibition, down regulation of EGFR expression, and NF-κB signaling affecting Bcl-2 expression. However, with serious side effects such as stroke and gastrointestinal bleeding, aspirin analogues with improved potency and side effect profiles are being developed. METHOD: Effects on cell viability following 24 hr incubation of four aspirin derivatives (PN508, 517, 526 and 529) were compared to cisplatin, aspirin and di-aspirin in four glioma cell lines (U87 MG, SVG P12, GOS – 3, and 1321N1), using the PrestoBlue assay, establishing IC50 and examining the time course of drug effects. RESULTS: All compounds were found to decrease cell viability in a concentration and time dependant manner. Significantly, the analogue PN517 (IC50 2mM) showed approximately a twofold increase in potency when compared to aspirin (3.7mM) and cisplatin (4.3mM) in U87 cells, with similar increased potency in SVG P12 cells. Other analogues demonstrated similar potency to aspirin and cisplatin. CONCLUSION: These results support the further development and characterization of novel NSAID derivatives for the treatment of glioma