Galactic periodicity and the oscillating G model

We consider the model involving the oscillation of the effective gravitational constant that has been put forward in an attempt to reconcile the observed periodicity in the galaxy number distribution with the standard cosmological models. This model involves a highly nonlinear dynamics which we analyze numerically. We carry out a detailed study of the bound that nucleosynthesis imposes on this model. The analysis shows that for any assumed value for $\Omega$ (the total energy density) one can fix the value of $\Omega_{\rm bar}$ (the baryonic energy density) in such a way as to accommodate the observational constraints coming from the $^4{\rm He}$ primordial abundance. In particular, if we impose the inflationary value $\Omega=1$ the resulting baryonic energy density turns out to be $\Omega_{\rm bar}\sim 0.021$. This result lies in the very narrow range $0.016 \leq \Omega_{\rm bar} \leq 0.026$ allowed by the observed values of the primordial abundances of the other light elements. The remaining fraction of $\Omega$ corresponds to dark matter represented by a scalar field.Comment: Latex file 29 pages with no figures. Please contact M.Salgado for figures. A more careful study of the model appears in gr-qc/960603

Indoor exposure to environmental tobacco smoke and dampness: respiratory symptoms in Sardinian children- DRIAS study

Indoorexposuresathome,environmentaltobaccosmoke(ETS)andmould/dampnessadverselyaffect respiratoryhealthofchildren.DisturbiRespiratorinell’InfanziaeAmbienteinSardegna(DRIAS) (RespiratorySymptomsinchildrenandtheEnvironmentinSardegna,Italy)aimsatrelatingthe prevalenceofrespiratoryandallergicsymptomstoindoorexposuresinSardinianchildren. DRIAS,across-sectionalinvestigationofrespiratorysymptoms/diseases,usedamodifiedversionof ISAACquestionnaire,included4122childrenattending29primaryschoolsintheschoolyear 2004–2005. If bothparentssmoketheprevalenceforcurrentwheezeandcurrentasthmaisalmostdoubledin comparisonwithneversmokers,forpersistentcoughandphlegmaroleissuggestedwhenonlymother smokes.Amongmotherssmokinginpregnancy,theprevalenceofcurrentwheezeandcurrentasthmais increased. ExposuretoETSandfamilyatopyhaveajointeffectresultinginanalmosttriplingof prevalenceforcurrentwheezeandmorethanfourtimesforcurrentasthma.Exposureto‘‘dampness’’ (mouldordampness)bothduringthefirstyearoflifeandcurrentlyisassociatedwithincreased prevalenceofcurrentwheeze,persistentcoughorphlegmandcurrentrhino-conjunctivitis;ifexposure is onlyduringthefirstyearoflifeadoublingormoreofprevalenceisobservedforcurrentwheeze, current asthma,andpersistentcoughorphlegm. DRIASresultsaddevidencetothecausalroleofchildhoodexposuretoETSinthedevelopmentof respiratorysymptoms(cough,phlegm,andwheezing)andasthma.ThejointeffectofETSandfamily atopyiscorroborated.Theresultsstrengthentheevidenceforacausalassociationbetween‘‘dampness’’ and respiratoryhealth,pointingtoitspossibleindependentroleincausingasthma,along-lasting exposureentailsadoubledprevalenceforbothasthmaticandbronchitissymptoms

COVID-19: not a contraindication for surgery in patients with proximal femur fragility fractures.

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Symmetric vacuum scalar--tensor cosmology

The existence of point symmetries in the cosmological field equations of generalized vacuum scalar--tensor theories is considered within the context of the spatially homogeneous cosmologies. It is found that such symmetries only occur in the Brans--Dicke theory when the dilaton field self--interacts. Moreover, the interaction potential of the dilaton must take the form of a cosmological constant. For the spatially flat, isotropic model, it is shown how this point symmetry may be employed to generate a discrete scale factor duality in the Brans--Dicke action.Comment: 10 pages, latex, To appear in Class. Quantum Gra

Finite Temperature and Density Effect on Symmetry Breaking by Wilson Loops

A finite temperature and density effect of Wilson loop elements on non-simply connected space is investigated in the model suggested by Hosotani. Using one-loop calculations it is shown that the value of an "order parameter" does not shift as the temperature grows. We find that finite density effect is of much importance for restoration of symmetry.Comment: 11pages, no figur

Analysis of Transaction Management Performance

There is currently much interest in incorporating transactions into both operating systems and general purpose programming languages. This paper provides a detailed examination of the design and performance of the“¢ transaction manager of the Camelot system. Camelot is a transaction facility that provides a rich model of transactions intended to support a wide variety of general-purpose applications. The transaction manager's principal function is to execute the protocols that ensure atomicity. The conclusions of this study are: a simple optimization to two-phase commit reduces logging activity of distributed transactions; non-blocking commit is practical for some applications; multithreaded design improves throughput provided that log batching is used; multi-casting reduces the variance of distributed commit protocols in a LAN environment; and the performance of transaction mechanisms such as Camelot depend heavily upon kernel performance

Constraints in the Context of Induced-gravity Inflation

Constraints on the required flatness of the scalar potential $V(\phi)$ for a cousin-model to extended inflation are studied. It is shown that, unlike earlier results, Induced-gravity Inflation can lead to successful inflation with a very simple lagrangian and $\lambda \sim 10^{-6}$, rather than $10^{-15}$ as previously reported. A second order phase transition further enables this model to escape the \lq big bubble' problem of extended inflation, while retaining the latter's motivations based on the low-energy effective lagrangians of supergravity, superstring, and Kaluza-Klein theories.Comment: 19 pp; 3 figures (not included -- available from author). Plain LaTeX. In press in Physical Review

Bianchi I Quantum cosmology in the Bergmann-Wagoner theory

The Wheeler-DeWitt equation is considered in the context of generalized scalar-tensor theories of gravitation for Bianchi type I cosmology. Exact solutions are found for two selfinteracting potentials and arbitary coupling function. The WKB wavefunctions are obtained and a family of solutions satisfying the Hawking-Page regularity conditions of wormholes are found.Comment: 12 pages, Latex fil