Central Exclusive Di-jet Production at the Tevatron

We perform a phenomenological analysis of dijet production in double pomeron exchange at the Tevatron. We find that the CDF Run I results do not rule out the presence of an exclusive dijet component, as predicted by Khoze, Martin and Ryskin (KMR). With the high statistics CDF Run II data, we predict that an exclusive component at the level predicted by KMR may be visible, although the observation will depend on accurate modelling of the inclusive double pomeron exchange process. We also compare to the predictions of the DPEMC Monte Carlo, which contains a non-perturbative model for the central exclusive process. We show that the perturbative model of KMR gives different predictions for the di-jet ET dependence in the high di-jet mass fraction region than non-perturbative models.Comment: 17 pages, 15 figure

Diffractive production of high pt photons at HERA

We study the diffractive production of high pt photons at HERA. We have implemented the process as a new hard sub-process in the HERWIG event generator in order to prepare the ground for a future measurement.Comment: 4 pages, 4 figures. Contribution to the 1999 UK Phenomenology Workshop on Collider Physics, Durham, U

A conceptual design study for the secondary mirror drive of the shuttle infrared telescope facility (SIRTF)

Various conceptual designs for the secondary mirror actuator system to be used in the Shuttle Infrared Telescope Facility (SIRTF) were evaluated. In addition, a set of design concepts was developed to assist in the solution of problems crucial for optimum performance of the secondary mirror actuator system. A specific conceptual approach was presented along with a plan for developing that approach and identifying issues of critical importance in the developmental effort

Revealing local failed supernovae with neutrino telescopes

We study the detectability of neutrino bursts from nearby direct black hole-forming collapses (failed supernovae) at Megaton detectors. Due to their high energetics, these bursts could be identified - by the time coincidence of N >= 2 or N >= 3 events within a ~ 1 s time window - from as far as ~ 4-5 Mpc away. This distance encloses several supernova-rich galaxies, so that failed supernova bursts could be detected at a rate of up to one per decade, comparable to the expected rate of the more common, but less energetic, neutron star-forming collapses. Thus, the detection of a failed supernova within the lifetime of a Mt detector is realistic. It might give the first evidence of direct black hole formation, with important implications on the physics of this phenomenon.Comment: LaTeX, 4 pages, 4 figures; minor changes to the text, results unchange

Parrondo-like behavior in continuous-time random walks with memory

The Continuous-Time Random Walk (CTRW) formalism can be adapted to encompass stochastic processes with memory. In this article we will show how the random combination of two different unbiased CTRWs can give raise to a process with clear drift, if one of them is a CTRW with memory. If one identifies the other one as noise, the effect can be thought as a kind of stochastic resonance. The ultimate origin of this phenomenon is the same of the Parrondo's paradox in game theoryComment: 8 pages, 3 figures, revtex; enlarged and revised versio

Factors invoved in onset and recovery from postnatal depression

Background: A wide variety of psychosocial variables have been implicated in the onset and recovery from postnatal depression. A number of these factors were examined on a representative sample of pregnant Maltese women attending St Luke's Hospital. Method: A random sample of 239 pregnant women were interviewed at booking using a detailed sociodemographic history, the Revised Version of the Clinical Interview Schedule (CIS-R) and Maltese translation of the Edinburgh Postnatal Depression Scale (EPDS). The CIS-R was again administered over the phone at 36 weeks and the EPDS sent by post. At eight weeks postpartum, the CIS-R, modified version of the Social Maladjustment Schedule and the EPDS were again administered to 95.8% of women. Results: Onset of depression in the postpartum was not predicted by depressive symptomatology during pregnancy, marital status, level of education, planning of pregnancy, woman's, partner's or family's reaction to pregnancy and marital adjustment. However being primiparous and employed during pregnancy were significantly associated with postnatal depression. In contrast, depressed women who remained depressed postnatally had a past personal psychiatry history and significantly higher scores on the CISR recorded at 36 weeks gestation. Limitation: The number of women examined in the study yielded a small number of depressed women, for which the results are limited in value. The sample is that of Maltese women booking in at the antenatal clinic, thus excluding women who present late, close to delivery date. The follow up period was limited to eight weeks postpartum only, excluding those who develop depressive episodes after 8 weeks. Conclusions: Some cases of postpartum depression may be traced back to pregnancy while others do not seem to be predictable during pregnancy further contributing evidence to the view that the prenatal period may be a separate entity from the postnatal period with regards to depressive illness.peer-reviewe

The monoclinic phase in PZT: new light on morphotropic phase boundaries

A summary of the work recently carried out on the morphotropic phase boundary (MPB) of PZT is presented. By means of x-ray powder diffraction on ceramic samples of excellent quality, the MPB has been successfully characterized by changing temperature in a series of closely spaced compositions. As a result, an unexpected monoclinic phase has been found to exist in between the well-known tetragonal and rhombohedral PZT phases. A detailed structural analysis, together with the investigation of the field effect in this region of compositions, have led to an important advance in understanding the mechanisms responsible for the physical properties of PZT as well as other piezoelectric materials with similar morphotropic phase boundaries.Comment: 5 pages REVTeX file, 6 figures embedded. Presented at the Workshop on "Fundamental Physics of Ferroelectrics" held in Aspen, February 00. To appear in the proceeding

Observing a Light CP-Violating Higgs Boson in Diffraction

Light CP-violating Higgs bosons with mass lower than 70 GeV might have escaped detection in direct searches at the LEP collider. They may remain undetected in conventional search channels at the Tevatron and LHC. In this Letter we show that exclusive diffractive reactions may be able to probe for the existence of these otherwise elusive Higgs particles. As a prototype example, we calculate diffractive production cross-sections of the lightest Higgs boson within the framework of the Minimal Supersymmetric Standard Model with explicit CP violation. Our analysis shows that the challenging regions of parameter space corresponding to a light CP-violating Higgs boson might be accessible at the LHC provided suitable proton tagging detectors are installed.Comment: 9 pages, LaTeX, 2 figures, version as to appear in Phys. Rev.

A hydrogen energy carrier. Volume 1: Summary

The production, technology, transportation, and implementation of hydrogen into the energy system are discussed along with the fossil fuel cycle, hydrogen fuel cycle, and the demands for energy. The cost of hydrogen production by coal gasification; electrolysis by nuclear energy, and solar energy are presented. The legal aspects of a hydrogen economy are also discussed

A Bayesian Analogue of Gleason's Theorem

We introduce a novel notion of probability within quantum history theories and give a Gleasonesque proof for these assignments. This involves introducing a tentative novel axiom of probability. We also discuss how we are to interpret these generalised probabilities as partially ordered notions of preference and we introduce a tentative generalised notion of Shannon entropy. A Bayesian approach to probability theory is adopted throughout, thus the axioms we use will be minimal criteria of rationality rather than ad hoc mathematical axioms.Comment: 14 pages, v2: minor stylistic changes, v3: changes made in-line with to-be-published versio