Gravitino Production After Inflation

We investigate the production of gravitinos in a cosmological background. Gravitinos can be produced during preheating after inflation due to a combined effect of interactions with an oscillating inflaton field and absence of conformal invariance. In order to get insight on conformal properties of gravitino we reformulate phenomenological supergravity in SU(2,2|1)-symmetric way. The Planck mass and F- and D-terms appear via the gauge-fixed value of a superfield that we call conformon. We find that in general the probability of gravitino production is not suppressed by the small gravitational coupling. This may lead to a copious production of gravitinos after inflation. Efficiency of the new non-thermal mechanism of gravitino production is very sensitive to the choice of the underlying theory. This may put strong constraints on certain classes of inflationary models.Comment: 18 pages, v2: the version to be published in Phys. Rev.D; v3: matching notations with longer paper hep-th/000617

Patterns and persistence of behavioural and psychological symptoms in those with cognitive impairment: the importance of apathy.

OBJECTIVE: To study the stability and emergence of a range of behavioural and psychological symptoms (BPS), their association with mortality and the effect of covariates on these transitions in a population-based study of cognitively impaired older people with a long follow-up period and large sample size, with a particular focus on apathy. METHODS: Data were from a population-based, longitudinal cohort study of ageing. Interviews were conducted at 0, 2, 6, 8 and 10 years with 3626 participants aged 65+. The persistence of 11 BPS and their association with mortality in those with cognitive impairment (MMSE 25 or below) was investigated using multi-state models, allowing us to take into account estimations of the probability of transitions that occurred in the time between interviews. RESULTS: Most BPS were persistent. Apathy was one of the most stable symptoms; in those with apathy, the probability of still having apathy after 1 year is 62%. Apathy, sleep problems, depression, irritability and wandering were most likely to develop. BPS are associated with mortality; in those with apathy, mortality is 3.1 times more likely than in those without apathy. Low cognitive function and dementia were associated with emergence of new symptoms. CONCLUSIONS: This population-based, multi-centre study with a follow-up period of 10 years showed that BPS are associated with mortality and most symptoms are persistent. Apathy was characterised by a high prevalence, a high persistence and a strong association with mortality, and has a negative impact on disability, management of other disease and caregiver burden.RvdL received a studentship from the National Institute for Health Research (NIHR) and the Collaborations for Leadership in Applied Health Research and Care (CLAHRC) for Cambridgeshire & Peterborough.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/gps.446

Quantum Cosmology and Higher-Order Lagrangian Theories

In this paper the quantum cosmological consequences of introducing a term cubic in the Ricci curvature scalar $R$ into the Einstein--Hilbert action are investigated. It is argued that this term represents a more generic perturbation to the action than the quadratic correction usually considered. A qualitative argument suggests that there exists a region of parameter space in which neither the tunneling nor the no-boundary boundary conditions predict an epoch of inflation that can solve the horizon and flatness problems of the big bang model. This is in contrast to the $R^2$--theory.Comment: 13 pages, LaTeX, preprint FERMILAB-Pub-94/XXX-A, March 199

Recycling universe

If the effective cosmological constant is non-zero, our observable universe may enter a stage of exponential expansion. In such case, regions of it may tunnel back to the false vacuum of an inflaton scalar field, and inflation with a high expansion rate may resume in those regions. An ``ideal'' eternal observer would then witness an infinite succession of cycles from false vacuum to true, and back. Within each cycle, the entire history of a hot universe would be replayed. If there were several minima of the inflaton potential, our ideal observer would visit each one of these minima with a frequency which depends on the shape of the potential. We generalize the formalism of stochastic inflation to analyze the global structure of the universe when this `recycling' process is taken into account.Comment: 43 pages, 10 figure

'n Ondersoek na die implementering van verdigting deur beleid binne Paarl munisipale gebied

Thesis (M. Town and regional planning)--Stellenbosch University , 2000.ENGLISH ABSTRACT: An ever increasing segment of the population in the current low density category contributes to the sprawling South African city as we know it today. To provide for the housing needs o f people, precious agricultural land is being used, and the historic character o f towns is being destroyed. Densification of the city structure has been put forward as a solution to this problem. In this way, different components of the city may be connected and existing infrastructure may be optimally utilised. The concept of densification is gaining popularity in all spheres o f planning. The implementation of densification requires suitable policy, as well as the strict application of the aforesaid. A densification policy must include consultation with all parties involved with a view to finding a balance between the need for land for development purposes, the conservation of agricultural land, the conservation of the historic character o f towns and cities, as well as being in the public interest. A theoretical investigation was done in which all aspects regarding densification, and its implementation in the South African context were studied. Attention was also given to policy formulation. This was followed by an empirical study, based on the Paarl municipal region as an example, in an attempt to reconcile theory and practice. It was found that although densification enjoys great support, the perception held by professional planners as to appropriate methods for the achievement o f higher densities did not correspond wholly with theoretical arguments in this regard. It was also found that it is important to view densification in relation to the environment in which it is applied, and to create an executable policy for a specifically designated area.AFRIKAANSE OPSOMMING: Snelgroeiende bevolkingsgetalle in ‘n lae-digtheidsmilieu dra by tot die uitgebreide Suid- Afrikaanse stad soos ons dit vandag ken. In die proses word kosbare landbougrond gebruik om in die behuisingsbehoefte van die mens te voorsien en die historiese karakter van dorpe word vernietig. As oplossing vir hierdie probleem word verdigting van die stad voorgestel, om sodoende verskillende komponente van die stad te verbind en reeds bestaande infrastruktuur tot die optimum te benut. Die konsep van verdigting geniet toenemende gewildheid in alle sfere van beplanning. Implementering van verdigting kan slegs deur die daarstelling van geskikte beleid en die toepassing daarvan geskied. By die formulering van ‘n verdigtingsbeleid moet alle rolspelers in die proses geraadpleeg word en ‘n middeweg tussen die behoefte aan grond vir ontwikkeling, die bewaring van kosbare landbougrond, die bewaring van die historiese karakter van ‘n stad en die publiek se belange gevind word. ‘n Deeglike teoretiese ondersoek is geloods, wat teoretiese aspekte omtrent verdigting en die implementering van verdigting binne die Suid-Afrikaanse konteks ondersoek het. Daar is ook aandag aan beleidsformulering gegee. Dit is opgevolg deur ‘n empiriese studie wat binne Paarl se munisipale gebied uitgevoer is en teoretiese inligting met die praktyk probeer versoen. In hierdie studie is bevind dat alhoewel verdigting van die stad groot ondersteuning geniet, die persepsie van professionele persone in die beplanningsprofessie oor metodes om hoër digthede te bereik, nie heeltemal met die voorgestelde metodes vervat in teoretiese bronne ooreenstem nie. Daar is ook bevind dat dit belangrik is om verdigting binne die konteks van die omgewing waarin dit toegepas word, te beskou en sodoende ‘n uitvoerbare beleid vir ‘n spesifieke omgewing op te stel.Maste

Partial reduction of anthracene by cold field emission in liquid in a microreactor with an integrated planar microstructured electrode

We report a novel microreactor with a photolithographically defined integrated electrode containing micro tips that serve as emission points for solvated electrons into liquid n-hexane in a microfluidic channel. The implementation of sharp electrode tips permits to extract electrons from the electrode material at relatively low voltages. The electric field distribution in the gap between a planar patterned platinum microtip array and a planar rectangular counterelectrode is analyzed by a computational model. Cold field emission using these microdevices is experimentally verified, and the partial reduction of anthracene to 9,10-dihydroanthracene, via solvated electrons emitted in solutions with or without ethanol in n-hexane is investigated. It is found that in the current microreactor configuration, the majority of the products are products originating from coupling of ethanol fragments to, and/or oxidation of 9,10-dihydroanthracene at the platinum counterelectrode, leaving no detectable yield of the desired reduction product

Water stress affects the germination, emergence, and growth of different sorghum cultivars

Two experiments were conducted to study the effects of water deficit stress on the germination, emergence and seedling growth of sorghum [Sorghum bicolor (L.) Moench] using Completely Randomised Block Design in four replications. Five sorghum cultivars (Jigurti, Gambella 1107, Meko, 76 T1 #23 and P9403) were evaluated under three water deficit stress treatments (0, -0.20 and -0.85 MPa) using PEG as an osmoticum (Experiment I) and under four varying growing media water contents (100, 60, 40 and 20% of field capacity) using sand (Experiment II). In both experiments, water deficit stress significantly reduced the rate and percentage of germination and emergence and early seedlings growth. Coleoptile, mesocotyl, radicle, and seedling shoot and root lengths, as well as root area were adversely affected by water deficit stress. Cultivars differed in the rate and percentage of germination, and emergence and seedling growth. Gambella 1107, Meko and P9403 had significantly (

Assessment of Motor Activities of Daily Living:Spanish Cross-Cultural Adaptation, Reliability and Construct Validity of the DCDDaily-Q

[Abstract] The DCDDaily-Q is an instrument that aims to comprehensively assess motor performance in a broad range of activities of daily living (ADL) and to identify risk of Developmental Coordination Disorder (DCD) in children. The aim of this study was to cross-culturally adapt the DCDDaily-Q into European Spanish (DCDDaily-Q-ES) and to test its psychometric properties in Spanish 5 to 10 year old children. The DCDDaily-Q was translated and cross-culturally adapted into Spanish following international guidelines. Two-hundred and seventy-six parents of typically developing Spanish children completed the final version of the DCDDaily-Q-ES (M = 7.5 years, SD = 1.7; girls = 50%). Confirmatory Factor Analysis (CFA), internal consistency, and corrected item-total correlations were conducted to test construct validity, internal consistency, and homogeneity of the DCDDaily-Q-ES. The DCDDaily-Q-ES achieved good semantic, conceptual, and cultural equivalence. CFA supported construct validity of the DCDDaily-Q-ES. Reliability values were also good (Cronbach’s alpha = 0.703–0.843; corrected item-total correlations = 0.262–0.567). This is the first study to cross-culturally adapt and examine the DCDDaily-Q outside the Netherlands. The findings suggest that the DCDDaily-Q-ES is a reliable and valid measure to assess learning, participation, and performance in a broad range of ADL.Xunta de Galicia; ED481A-2018/15