84 research outputs found
A natural orbital method for the electron momentum distribution in matter
A variational method for many electron system is applied to momentum
distribution calculations. The method uses a generating two-electron geminal
and the amplitudes of the occupancies of one particle natural orbitals as
variational parameters. It introduces correlation effects beyond the free
fermion nodal structure.Comment: 3 pages, Latex, revised paper with new reference
Entanglement as Measure of Electron-Electron Correlation in Quantum Chemistry Calculations
In quantum chemistry calculations, the correlation energy is defined as the
difference between the Hartree-Fock limit energy and the exact solution of the
nonrelativistic Schrodinger equation. With this definition, the electron
correlation effects are not directly observable. In this report, we show that
the entanglement can be used as an alternative measure of the electron
correlation in quantum chemistry calculations. Entanglement is directly
observable and it is one of the most striking properties of quantum mechanics.
As an example we calculate the entanglement for He atom and H2 molecule with
different basis sets.Comment: 12 pages, 2 figure
Majorana: from atomic and molecular, to nuclear physics
In the centennial of Ettore Majorana's birth (1906-1938?), we re-examine some
aspects of his fundamental scientific production in atomic and molecular
physics, including a not well known short communication. There, Majorana
critically discusses Fermi's solution of the celebrated Thomas-Fermi equation
for electron screening in atoms and positive ions. We argue that some of
Majorana's seminal contributions in molecular physics already prelude to the
idea of exchange interactions (or Heisenberg-Majorana forces) in his later
workson theoretical nuclear physics. In all his papers, he tended to emphasize
the symmetries at the basis of a physical problem, as well as the limitations,
rather than the advantages, of the approximations of the method employed.Comment: to appear in Found. Phy
Recommended from our members
Cognitive-behavioural therapy and short-term psychoanalytic psychotherapy versus brief psychosocial intervention in adolescents with unipolar major depression (IMPACT): a multicentre, pragmatic, observer-blind, randomised controlled trial.
Although there are effective psychological treatments for unipolar major depression in adolescents, whether or not one or more of the available therapies maintain reduced depressive symptoms 1 year after the end of treatment is not known. This is a non-trivial issue because maintaining lowered depressive symptoms below a clinical threshold level reduces the risk for diagnostic relapse into the adult years. To determine whether or not either of two specialist psychological treatments, cognitive-behavioural therapy (CBT) or short-term psychoanalytic psychotherapy (STPP), is more effective than a reference brief psychosocial intervention (BPI) in maintaining reduction of depression symptoms in the year after treatment. Observer-blind, parallel-group, pragmatic superiority randomised controlled trial. A total of 15 outpatient NHS clinics in the UK from East Anglia, north-west England and North London. Adolescents aged 11-17 years with Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition major depression including those with suicidality, depressive psychosis and conduct disorder. Patients were randomised using stochastic minimisation controlling for age, sex and self-reported depression sum score; 470 patients were randomised and 465 were included in the analyses. In total, 154 adolescents received CBT, 156 received STPP and 155 received BPI. The trial lasted 86 weeks and study treatments were delivered in the first 36 weeks, with 52 weeks of follow-up. Mean sum score on self-reported depressive symptoms (primary outcome) at final study assessment (nominally 86 weeks, at least 52 weeks after end of treatment). Secondary measures were change in mean sum scores on self-reported anxiety symptoms and researcher-rated Health of the Nation scales for children and adolescents measuring psychosocial function. Following baseline assessment, there were a further five planned follow-up reassessments at nominal time points of 6, 12, 52 and 86 weeks post randomisation. There were non-inferiority effects of CBT compared with STPP [treatment effect by final follow-up = -0.578, 95% confidence interval (CI) -2.948 to 4.104; p = 0.748]. There were no superiority effects for the two specialist treatments (CBT + STPP) compared with BPI (treatment effect by final follow-up = -1.898, 95% CI -4.922 to 1.126; p = 0.219). At final assessment there was no significant difference in the mean depressive symptom score between treatment groups. There was an average 49-52% reduction in depression symptoms by the end of the study. There were no differences in total costs or quality-of-life scores between treatment groups and prescribing a selective serotonin reuptake inhibitor (SSRI) during treatment or follow-up did not differ between the therapy arms and, therefore, did not mediate the outcome. The three psychological treatments differed markedly in theoretical and clinical approach and are associated with a similar degree of clinical improvement, cost-effectiveness and subsequent maintenance of lowered depressive symptoms. Both STPP and BPI offer an additional patient treatment choice, alongside CBT, for depressed adolescents attending specialist Child and Adolescent Mental Health Services. Further research should focus on psychological mechanisms that are associated with treatment response, the maintenance of positive effects, determinants of non-response and whether or not brief psychotherapies are of use in primary care and community settings. Neither reason for SSRI prescribing or monitoring of medication compliance was controlled for over the course of the study, and the economic results were limited by missing data. Current Controlled Trials ISRCTN83033550. This project was funded by the National Institute for Heath Research Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 12. See the National Institute for Heath Research Journals Library website for further project information. Funding was also provided by the Department of Health. The funders had no role in the study design, patient recruitment, data collection, analysis or writing of the study, any aspect pertinent to the study or the decision to submit to The Lancet
When Institutional Work Backfires: Organizational Control Of Professional Work In The Pharmaceutical Industry
Integrating institutional and role theories, this paper develops a Logics–Roles– Action (LRA) framework for understanding how for-profit organizations structure institutional work to managerially control the work of professionals they employ. Structurally, this institutional work involves three elements: (1) internalizing pluralistic logics (logics); (2) institutionalizing distinct roles embedded in these logics (roles); and (3) scripting goal-oriented role enactment plans (action). An empirical examination of the LRA framework in the pharmaceutical industry evidences four distinct organizational strategies that script role enactments of sales professionals in their interactions with physicians. Each strategy is intended to reaffirm prevailing institutional logics, but eventually backfires by disrupting the very institutional structures that it seeks to maintain and replicate. We show that this disruptive effect is mediated by changes in the social knowledge of institutional work. We close with theoretical and managerial implications for organizational structuring of institutional work and dynamics of institutional change
Study of DJ meson decays to D+π−, D0π+ and D∗+π− final states in pp collisions
A study of D+π−, D0π+ and D∗+π− final states is performed using pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, collected at a centre-of-mass energy of 7 TeV with the LHCb detector. The D1(2420)0 resonance is observed in the D∗+π− final state and the D∗2(2460) resonance is observed in the D+π−, D0π+ and D∗+π− final states. For both resonances, their properties and spin-parity assignments are obtained. In addition, two natural parity and two unnatural parity resonances are observed in the mass region between 2500 and 2800 MeV. Further structures in the region around 3000 MeV are observed in all the D∗+π−, D+π− and D0π+ final states
La tassonomia XBRL italiana della nota integrativa: analisi delle fonti normative
Through a wide-ranging critical review of relevant publications, we explore and articulate what constitutes the sensemaking perspective in organization studies, as well as its range of applications and limitations. More specifically, we argue that sensemaking in organizations has been seen as consisting of specific episodes, is triggered by ambiguous events, occurs through specific processes, generates specific outcomes, and is influenced by several situational factors. Furthermore, we clarify the application range of the sensemaking perspective and identify, as well as account for, the types and aspects of organizational sensemaking that have been under-researched. We critically discuss the criticism that the sensemaking perspective has received so far and selectively expand on it. Finally, we identify the main limitations of the sensemaking perspective, which, if tackled, will advance it: the neglect of prospective sensemaking, the exclusive focus on disruptive episodes at the expense of more mundane forms of sensemaking implicated in routine activities, the ambiguous status of enactment, the conflation of first-order and second-order sensemaking, and the lack of proper attention to embodied sensemaking. Copyright © 2014 John Wiley & Sons, Ltd
Analysis of the resonant components in Bs->J/\psi\pi+\pi-
The decay Bs->J/\psi\pi+\pi- can be exploited to study CP violation. A
detailed understanding of its structure is imperative in order to optimize its
usefulness. An analysis of this three-body final state is performed using a
1.0/fb sample of data produced in 7 TeV pp collisions at the LHC and collected
by the LHCb experiment. A modified Dalitz plot analysis of the final state is
performed using both the invariant mass spectra and the decay angular
distributions. The \pi+\pi- system is shown to be dominantly in an S-wave
state, and the CP-odd fraction in this Bs decay is shown to be greater than
0.977 at 95% confidence level. In addition, we report the first measurement of
the J/\psi\pi+\pi- branching fraction relative to J/\psi\phi\ of (19.79 +/-
0.47 +/- 0.52)%.Comment: 28 pages, 18 figures, updated after journal revie
Prediction of collective characteristics for ion ensembles in quadrupole ion traps without trajectory simulations
- …