N identical particles under quantum confinement: A many-body dimensional perturbation theory approach

Systems that involve N identical interacting particles under quantum confinement appear throughout many areas of physics, including chemical, condensed matter, and atomic physics. In this paper, we present the methods of dimensional perturbation theory, a powerful set of tools that uses symmetry to yield simple results for studying such many-body systems. We present a detailed discussion of the dimensional continuation of the N-particle Schrodinger equation, the spatial dimension D -> infinity equilibrium (D^0) structure, and the normal-mode (D^{-1}) structure. We use the FG matrix method to derive general, analytical expressions for the many-body normal-mode vibrational frequencies, and we give specific analytical results for three confined N-body quantum systems: the N-electron atom, N-electron quantum dot, and N-atom inhomogeneous Bose-Einstein condensate with a repulsive hardcore potential

Conformal Field Theory Approach to the 2-Impurity Kondo Problem: Comparison with Numerical Renormalization Group Results

Numerical renormalization group and conformal field theory work indicate that the two impurity Kondo Hamiltonian has a non-Fermi liquid critical point separating the Kondo-screening phase from the inter-impurity singlet phase when particle-hole (P-H) symmetry is maintained. We clarify the circumstances under which this critical point occurs, pointing out that there are two types of P-H symmetry. Only one of them guarantees the occurance of the critical point. Much of the previous numerical work was done on models with the other type of P-H symmetry. We analyse this critical point using the boundary conformal field theory technique. The finite-size spectrum is presented in detail and compared with about 50 energy levels obtained using the numerical renormalization group. Various Green's functions, general renormalization group behaviour, and a hidden $SO(7)$ are analysed.Comment: 38 pages, RevTex. 2 new sections clarify the circumstances under which a model will exhibit the non-trivial critical point (hence potentially resolving disagreements with other Authors) and explain the hidden SO(7) symmetry of the model, relating it to an alternative approach of Sire et al. and Ga

Coordinate Representation of the One-Spinon One-Holon Wavefunction and Spinon-Holon Interaction

By deriving and studying the coordinate representation for the one-spinon one-holon wavefunction we show that spinons and holons in the supersymmetric $t - J$ model with $1/r^2$ interaction attract each other. The interaction causes a probability enhancement in the one-spinon one-holon wavefunction at short separation between the particles. We express the hole spectral function for a finite lattice in terms of the probability enhancement, given by the one-spinon one-holon wavefunction at zero separation. In the thermodynamic limit, the spinon-holon attraction turns into the square-root divergence in the hole spectral function.Comment: 20 pages, 3 .eps figure

Niobium based intermetallics as a source of high-current/high-magnetic field superconductors

The article is focused on low temperature intermetallic A15 superconducting wires development for Nuclear Magnetic Resonance, NMR, and Nuclear Magnetic Imaging, MRI, magnets and also on cryogen-free magnets. There are many other applications which would benefit from new development such as future Large Hadron Collider to be built from A15 intermetallic conductors. This paper highlights the current status of development of the niobium based intermetallics with special attention to Nb 3 (Al 1-x, Ge x). Discussion is focused on the materials science aspects of conductor manufacture, such as b-phase (A15) formation, with particular emphasis on the maximisation of the superconducting parameters, such as critical current density, Jc, critical temperature, Tc, and upper critical field, Hc2 . Many successful manufacturing techniques of the potential niobium-aluminide intermetallic superconducting conductors, such as solid-state processing, liquid-solid processing, rapid heating/cooling processes, are described, compared and assessed. Special emphasis has been laid on conditions under which the Jc (B) peak effect occurs in some of the Nb3(Al,Ge) wires. A novel electrodeoxidizing method developed in Cambridge whereby the alloys and intermetallics are produced cheaply making all superconducting electromagnetic devices, using low cost LTCs, more cost effective is presented.This new technique has potential to revolutionise the existing superconducting industry enabling reduction of cost orders of magnitude.Comment: Paper presented at EUCAS'01 conference, Copenhagen, 26-30 August 200

Generalized Drinfeld-Sokolov Reductions and KdV Type Hierarchies

Generalized Drinfeld-Sokolov (DS) hierarchies are constructed through local reductions of Hamiltonian flows generated by monodromy invariants on the dual of a loop algebra. Following earlier work of De Groot et al, reductions based upon graded regular elements of arbitrary Heisenberg subalgebras are considered. We show that, in the case of the nontwisted loop algebra $\ell(gl_n)$, graded regular elements exist only in those Heisenberg subalgebras which correspond either to the partitions of $n$ into the sum of equal numbers $n=pr$ or to equal numbers plus one $n=pr+1$. We prove that the reduction belonging to the grade $1$ regular elements in the case $n=pr$ yields the $p\times p$ matrix version of the Gelfand-Dickey $r$-KdV hierarchy, generalizing the scalar case $p=1$ considered by DS. The methods of DS are utilized throughout the analysis, but formulating the reduction entirely within the Hamiltonian framework provided by the classical r-matrix approach leads to some simplifications even for $p=1$.Comment: 43 page

Personality Traits in Juvenile Delinquents: Associations with Peer and Family Relations

Objective: To establish family and peer correlates of personality traits shown to be predictive of future criminal recidivism. Method: 137 incarcerated boys aged 13-18 (x = 16 ± 1.2), 35% black, 21% Hispanic, 43% white, and 1% other completed the Weinberger Adjustment Inventory (WAI) and a psychosocial history obtained by a social worker. Records were summarized using two raters who assigned numerical ratings to dimensions of family and peer relations. Results: As expected, observer ratings of family and peer relationships were correlated with the personality characteristics of distress, denial and restraint as measured by the WAI. Conclusion: Family and peer relations are associated with certain personality traits that are predictive of criminal recidivism in delinquents. This study further expands the knowledge base regarding the social and interpersonal correlates of individual traits predicting criminal recidivism

Enhancement of the Two-channel Kondo Effect in Single-Electron boxes

The charging of a quantum box, coupled to a lead by tunneling through a single resonant level, is studied near the degeneracy points of the Coulomb blockade. Combining Wilson's numerical renormalization-group method with perturbative scaling approaches, the corresponding low-energy Hamiltonian is solved for arbitrary temperatures, gate voltages, tunneling rates, and energies of the impurity level. Similar to the case of a weak tunnel barrier, the shape of the charge step is governed at low temperatures by the non-Fermi-liquid fixed point of the two-channel Kondo effect. However, the associated Kondo temperature TK is strongly modified. Most notably, TK is proportional to the width of the level if the transmission through the impurity is close to unity at the Fermi energy, and is no longer exponentially small in one over the tunneling matrix element. Focusing on a particle-hole symmetric level, the two-channel Kondo effect is found to be robust against the inclusion of an on-site repulsion on the level. For a large on-site repulsion and a large asymmetry in the tunneling rates to box and to the lead, there is a sequence of Kondo effects: first the local magnetic moment that forms on the level undergoes single-channel screening, followed by two-channel overscreening of the charge fluctuations inside the box.Comment: 21 pages, 19 figure

Safety of nifedipine GITS in stable angina: The ACTION trial

Aim: We describe the safety profile of nifedipine GITS as assessed from adverse events reported in the ACTION trial in which 7,665 patients with stable, symptomatic coronary artery disease were randomly assigned nifedipine GITS or placebo and followed for a mean of 4.9 years. Methods: All adverse events were coded using the COSTART coding dictionary. The incidence rate for each event was calculated as the number of patients with the event concerned divided by the total time 'at risk'. Hazard ratios comparing nifedipine with placebo and their 95% confidence intervals were obtained by Cox proportional-hazards analysis. Results: As reported previously, nifedipine significantly reduced the incidence of cardiovascular events and procedures [hazard ratio (HR) 0.89, 95% confidence interval (CI) 0.83-0.95]. Apart from the known side effects of nifedipine, which include peripheral oedema, vasodilatation, hypotension, asthenia, constipation, leg cramps, non-specific respiratory complaints, impotence and polyuria, and which were reported more frequently in patients assigned nifedipine, the incidence rates of most other adverse events were similar. There were no differences in the occurrence of gastrointestinal haemorrhage, myocardial infarction and suicide. The rate of occurrence of death or new cancer excluding non-melanoma skin cancer for patients with no history of cancer at baseline was 2.53/100 patient years for patients assigned nifedipine and 2.37/100 patient years for patients assigned placebo (HR 1.06, 95% CI 0.93-1.22). Conclusion: Overall nifedipine GITS was well tolerated by patients with stable symptomatic angina

The discontinuous nature of chromospheric activity evolution

Chromospheric activity has been thought to decay smoothly with time and, hence, to be a viable age indicator. Measurements in solar type stars in open clusters seem to point to a different conclusion: chromospheric activity undergoes a fast transition from Hyades level to that of the Sun after about 1 Gyr of main--sequence lifetime and any decaying trend before or after this transition must be much less significant than the short term variations.Comment: 6 pages, 1 figure, to be published in Astrophysics and Space Scienc

Gemini Observations of Disks and Jets in Young Stellar Objects and in Active Galaxies

We present first results from the Near-infrared Integral Field Spectrograph (NIFS) located at Gemini North. For the active galaxies Cygnus A and Perseus A we observe rotationally-supported accretion disks and adduce the existence of massive central black holes and estimate their masses. In Cygnus A we also see remarkable high-excitation ionization cones dominated by photoionization from the central engine. In the T-Tauri stars HV Tau C and DG Tau we see highly-collimated bipolar outflows in the [Fe II] 1.644 micron line, surrounded by a slower molecular bipolar outflow seen in the H_2 lines, in accordance with the model advocated by Pyo et al. (2002).Comment: Invited paper presented at the 5th Stromlo Symposium. 9 pages, 7 figures. Accepted for publication in Astrophysics & Space Scienc