An Improved Semi-Analytical Spherical Collapse Model for Non-linear Density Evolution

We derive a semi-analytical extension of the spherical collapse model of structure formation that takes account of the effects of deviations from spherical symmetry and shell crossing which are important in the non-linear regime. Our model is designed so that it predicts a relation between the peculiar velocity and density contrast that agrees with the results of N-body simulations in the region where such a comparison can sensibly be made. Prior to turnaround, when the unmodified spherical collapse model is expect to be a good approximation, the predictions of the two models coincide almost exactly. The effects of a late time dominating dark energy component are also taken into account. The improved spherical collapse model is a useful tool when one requires a good approximation not just to the evolution of the density contrast but also its trajectory. Moreover, the analytical fitting formulae presented is simple enough to be used anywhere where the standard spherical collapse might be used but with the advantage that it includes a realistic model of the effects of virialisation.Comment: 6 pages, 3 figures. Matches the version in print at Astrophys.

The Dilaton and Modified Gravity

We consider the dilaton in the strong string coupling limit and elaborate on the original idea of Damour and Polyakov whereby the dilaton coupling to matter has a minimum with a vanishing value at finite field-value. Combining this type of coupling with an exponential potential, the effective potential of the dilaton becomes matter density dependent. We study the background cosmology, showing that the dilaton can play the role of dark energy. We also analyse the constraints imposed by the absence of violation of the equivalence principle. Imposing these constraints and assuming that the dilaton plays the role of dark energy, we consider the consequences of the dilaton on large scale structures and in particular the behaviour of the slip functions and the growth index at low redshift.Comment: 14 pages, 4 figure

Preparation, Characterization, Electrochemistry, and Infrared Spectroelectrochemistry of Ruthenium Nitrosyl Porphyrins Containing η1-O Bonded Axial Carboxylates

The synthesis, characterization and redox behavior of eight low-spin nitrosyl carboxylate compounds (por)Ru(NO)(η1-OC(=O)R) (por = T(p-OMe)PP: R = Me (1), i-Pr (2), t-Bu (3), p-C6H4NO2 (4), Fc (5), CF3 (8); por = TTP: R = Fc (6)) and (T(p-OMe)PP)Ru(NO)(OC6HF4) (7) are reported. The compounds are moderately stable in air as solids. Their IR (KBr) spectral data show ʋNO\u27s in the 1839-1861 range cm-1. The X-ray crystal structures of compounds 1, 2, 5-7, and 8 have been determined, and reveal linear RuNO linkages for these formally {RuNO}6 complexes. The redox behavior of the compounds at a Pt working electrode were studied in CH2Cl2 with NBu4PF6 as supporting electrolyte. The compounds display reversible first oxidations. IR spectroelectrochemistry of compounds 1-4, 7 and 8 revealed porphyrin centered oxidations, whereas the ferrocenylcarboxylate compounds revealed first oxidations at the ferrocenyl moiety followed by second oxidations at the porphyrin macrocycles. Reductions of these compounds are accompanied by loss of the axial ligands

Comparison of Mycobacterium tuberculosis genomes reveals frequent deletions in a 20 kb variable region in clinical isolates. Yeast 17:272–282

Abstract The Mycobacterium tuberculosis complex is associated with a remarkably low level of structural gene polymorphism. As part of a search for alternative forms of genetic variation that may act as a source of biological diversity in M. tuberculosis, we have identi®ed a region of the genome that is highly variable amongst a panel of unrelated clinical isolates. Fifteen of 24 isolates examined contained one or more copies of the M. tuberculosis-speci®c IS6110 insertion element within this 20 kb variable region. In nine of the isolates, including the laboratory-passaged strain H37Rv, genomic deletions were identi®ed, resulting in loss of between two and 13 genes. In each case, deletions were associated with the presence of a copy of the IS6110 element. Absence of¯anking tri-or tetra-nucleotide repeats identi®ed homologous recombination between adjacent IS6110 elements as the most likely mechanism of the deletion events. IS6110 insertion into hotspots within the genome of M. tuberculosis provides a mechanism for generation of genetic diversity involving a high frequency of insertions and deletions

A Testable Solution of the Cosmological Constant and Coincidence Problems

We present a new solution to the cosmological constant (CC) and coincidence problems in which the observed value of the CC, $\Lambda$, is linked to other observable properties of the universe. This is achieved by promoting the CC from a parameter which must to specified, to a field which can take many possible values. The observed value of Lambda ~ 1/(9.3 Gyrs)^2$(approximately 10^(-120) in Planck units) is determined by a new constraint equation which follows from the application of a causally restricted variation principle. When applied to our visible universe, the model makes a testable prediction for the dimensionless spatial curvature of Omega_k0 = -0.0056 s_b/0.5; where s_b ~ 1/2 is a QCD parameter. Requiring that a classical history exist, our model determines the probability of observing a given Lambda. The observed CC value, which we successfully predict, is typical within our model even before the effects of anthropic selection are included. When anthropic selection effects are accounted for, we find that the observed coincidence between t_Lambda = Lambda^(-1/2) and the age of the universe, t_U, is a typical occurrence in our model. In contrast to multiverse explanations of the CC problems, our solution is independent of the choice of a prior weighting of different$\Lambda$-values and does not rely on anthropic selection effects. Our model includes no unnatural small parameters and does not require the introduction of new dynamical scalar fields or modifications to general relativity, and it can be tested by astronomical observations in the near future.Comment: 31 pages, 4 figures; v2: version accepted by Phys. Rev.

Sexual harassment and abuse in sport: The research context

This special issue of the Journal of Sexual Aggression draws on the contributions to a Symposium on ‘Sexual Harassment in Sport – Challenges for Sport Psychology in the New Millennium’, held at the Xth Congress of the International Society for Sport Psychology, Skiathos, Greece from May 28th to June 2nd 2001. The symposium, which was organised by the authors of this editorial, was intended to move forward the international research agenda on sexual harassment and abuse in sport and to examine professional practice issues for sport psychologists. It was clear from the attendance of over 60 delegates at that symposium that international interest in this subject is growing. Further evidence of this came from the attendance of 26 members states – from Azerbaijan to Sweden - at a Council of Europe seminar on The Protection of Children, Young People and Women in Sport, held in Helsinki in September 2001

Quantification of ethyl glucuronide, ethyl sulfate, nicotine, and its metabolites in human fetal liver and placenta

This research was supported by the Medical Research Council (UK) grant MR/L010011/1 and the Intramural Research Program at the National Institute on Drug Abuse of the National Institutes of Health. Paired fetal liver and placenta samples were graciously provided by the Joint Medical Research Council/Wellcome Trust (grant number 099175/Z/12/Z) Human Developmental Biology Resource (www.hdbr.org). The online version of this article (doi:10.1007/s11419-017-0389-2) contains supplementary material, which is available to authorized users.Peer reviewedPostprin

Characterisation and expression of SPLUNC2, the human orthologue of rodent parotid secretory protein

We recently described the Palate Lung Nasal Clone (PLUNC) family of proteins as an extended group of proteins expressed in the upper airways, nose and mouth. Little is known about these proteins, but they are secreted into the airway and nasal lining fluids and saliva where, due to their structural similarity with lipopolysaccharide-binding protein and bactericidal/permeability-increasing protein, they may play a role in the innate immune defence. We now describe the generation and characterisation of novel affinity-purified antibodies to SPLUNC2, and use them to determine the expression of this, the major salivary gland PLUNC. Western blotting showed that the antibodies identified a number of distinct protein bands in saliva, whilst immunohistochemical analysis demonstrated protein expression in serous cells of the major salivary glands and in the ductal lumens as well as in cells of minor mucosal glands. Antibodies directed against distinct epitopes of the protein yielded different staining patterns in both minor and major salivary glands. Using RT-PCR of tissues from the oral cavity, coupled with EST analysis, we showed that the gene undergoes alternative splicing using two 5' non-coding exons, suggesting that the gene is regulated by alternative promoters. Comprehensive RACE analysis using salivary gland RNA as template failed to identify any additional exons. Analysis of saliva showed that SPLUNC2 is subject to N-glycosylation. Thus, our study shows that multiple SPLUNC2 isoforms are found in the oral cavity and suggest that these proteins may be differentially regulated in distinct tissues where they may function in the innate immune response

Dark spinor models in gravitation and cosmology

We introduce and carefully define an entire class of field theories based on non-standard spinors. Their dominant interaction is via the gravitational field which makes them naturally dark; we refer to them as Dark Spinors. We provide a critical analysis of previous proposals for dark spinors noting that they violate Lorentz invariance. As a working assumption we restrict our analysis to non-standard spinors which preserve Lorentz invariance, whilst being non-local and explicitly construct such a theory. We construct the complete energy-momentum tensor and derive its components explicitly by assuming a specific projection operator. It is natural to next consider dark spinors in a cosmological setting. We find various interesting solutions where the spinor field leads to slow roll and fast roll de Sitter solutions. We also analyse models where the spinor is coupled conformally to gravity, and consider the perturbations and stability of the spinor.Comment: 43 pages. Several new sections and details added. JHEP in prin