Incorporating Radial Flow in the Lattice Gas Model for Nuclear Disassembly

We consider extensions of the lattice gas model to incorporate radial flow. Experimental data are used to set the magnitude of radial flow. This flow is then included in the Lattice Gas Model in a microcanonical formalism. For magnitudes of flow seen in experiments, the main effect of the flow on observables is a shift along the $E^*/A$ axis.Comment: Version accepted for publication in Phys. Rev. C, Rapid Communicatio

Two Dimensional Triptycene End‐Capping and Its Influence on the Self‐Assembly of Quinoxalinophenanthrophenazines †

In this report we investigated two-dimensionally triptycene end-capped QPPs in terms of their solution and solid-state behavior. For this purpose, a triphenylene based ortho-diamine decorated with two triptycenyl units as well as a phenylene diamine with two non-annulated triptycene units have been synthesized. Sequences of condensation reactions with a pyrene-based tetraketone and ortho-diamines yielded a series of QPPs and UV/Vis investigations of the corresponding compounds led to the conclusion, that the QPPs form dimers in solution, which was further supported by MALDI-TIMS-TOF-MS. Single-crystal X-ray analysis of the triply and quadruply triptycene end-capped QPPs furthermore showed short π-π-distances of 3.3—3.4 Å and a perfect shape match during the dimerization of the triply triptycenyl end-capped QPP making it possible synthon fo

Fragment Formation in Central Heavy Ion Collisions at Relativistic Energies

We perform a systematic study of the fragmentation path of excited nuclear matter in central heavy ion collisions at the intermediate energy of $0.4 AGeV$. The theoretical calculations are based on a Relativistic Boltzmann-Uehling-Uhlenbeck ($RBUU$) transport equation including stochastic effects. A Relativistic Mean Field ($RMF$) approach is used, based on a non-linear Lagrangian, with coupling constants tuned to reproduce the high density results of calculations with correlations. At variance with the case at Fermi energies, a new fast clusterization mechanism is revealed in the early compression stage of the reaction dynamics. Fragments appear directly produced from phase-space fluctuations due to two-body correlations. In-medium effects of the elastic nucleon-nucleon cross sections on the fragmentation dynamics are particularly discussed. The subsequent evolution of the primordial clusters is treated using a simple phenomenological phase space coalescence algorithm. The reliability of the approach, formation and recognition, is investigated in detail by comparing fragment momentum space distributions {\it and simultaneously} their yields with recent experimental data of the $FOPI$ collaboration by varying the system size of the colliding system, i.e. its compressional energy (pressure, radial flow). We find an excellent agreement between theory and experiment in almost all the cases and, on the other hand, some limitations of the simple coalescence model. Furthermore, the temporal evolution of the fragment structure is explored with a clear evidence of an earlier formation of the heavier clusters, that will appear as interesting $relics$ of the high density phase of the nuclear Equation of State ($EoS$).Comment: 21 pages, 8 figures, Latex Elsart Style, minor corrections in p.7, two refs. added, Nucl.Phys.A, accepte

Statistical Multifragmentation in Central Au+Au Collisions at 35 MeV/u

Multifragment disintegrations, measured for central Au + Au collisions at E/A = 35 MeV, are analyzed with the Statistical Multifragmentation Model. Charge distributions, mean fragment energies, and two-fragment correlation functions are well reproduced by the statistical breakup of a large, diluted and thermalized system slightly above the multifragmentation threshold.Comment: Latex file, 8 pages + 4 postscript figures available upon request from [email protected]

Circumstantial Evidence for a Critical Behavior in Peripheral Au + Au Collisions at 35 MeV/nucleon

The fragmentation resulting from peripheral Au + Au collisions at an incident energy of E = 35 MeV/nucleon is investigated. A power-law charge distribution, $A^{-\tau}$ with $\tau \approx 2.2$, and an intermittency signal are observed for events selected in the region of the Campi scatter plot where "critical" behavior is expected.Comment: 11 pages, RevTex file, 4 postscript figures available upon request from [email protected]

Units and Numerical Values of the Effective Couplings in Perturbative Heterotic String Vacua

We determine the units and numerical values for a class of couplings in the effective theory of perturbative heterotic string vacua, with the emphasis on the correct translation between the canonical gauge coupling g and Planck scale M_Planck ~ 1.2 x 10^19 GeV as used in the effective theory description and the string coupling g_string and string tension alpha' as used in the S-matrix amplitude calculation. In particular, we determine the effective couplings in the superpotential and revisit the Fayet-Iliopoulos (FI) term in a class of models with an anomalous U(1). We derive the values of the effective Yukawa couplings (at the third and fourth order) after the restabilization of vacuum along a particular F- and D-flat direction and show that they are comparable in magnitude. The result corrects results quoted in the literature, and may have implications for the string derived phenomenology, e.g., that of fermion textures.Comment: RevTeX, 8p

Willingness to participate in future HIV prevention studies among gay and bisexual men in Scotland, UK: a challenge for intervention trials

This article examines willingness to participate in future HIV prevention research among gay and bisexual men in Scotland, UK. Anonymous, self-complete questionnaires and Orasure Gäó oral fluid samples were collected in commercial gay venues. 1,320 men were eligible for inclusion. 78.2% reported willingness to participate in future HIV prevention research; 64.6% for an HIV vaccine, 57.4% for a behaviour change study, and 53.0% for a rectal microbicide. In multivariate analysis, for HIV vaccine research, greater age, minority ethnicity, and not providing an oral fluid sample were associated with lower willingness; heterosexual orientation and not providing an oral fluid sample were for microbicides; higher education and greater HIV treatment optimism were for behaviour change. STI testing remained associated with being more willing to participate in microbicide research and frequent gay scene use remained associated with being more willing to participate in behaviour change research. Having an STI in the past 12 months remained significantly associated with being willing to participate in all three study types. There were no associations between sexual risk behaviour and willingness. Although most men expressed willingness to participate in future research, recruitment of high-risk men, who have the potential to benefit most, is likely to be more challenging

A statistical interpretation of the correlation between intermediate mass fragment multiplicity and transverse energy

Multifragment emission following Xe+Au collisions at 30, 40, 50 and 60 AMeV has been studied with multidetector systems covering nearly 4-pi in solid angle. The correlations of both the intermediate mass fragment and light charged particle multiplicities with the transverse energy are explored. A comparison is made with results from a similar system, Xe+Bi at 28 AMeV. The experimental trends are compared to statistical model predictions.Comment: 7 pages, submitted to Phys. Rev.

The nocturnal activity of a commonly housed rodent: How African pygmy dormice (Graphiurus murinus) respond to an enriched environment

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordExotic rodents are becoming increasingly popular in industry, however, there is limited empirical evidence to guide husbandry practices. African pygmy dormice (Graphiurus murinus) are typical in this respect. This research aimed to determine the effect of environmental enrichment on the behavior (including stereotypical scratching at the glass walls of the enclosure) and space use of a group of eight African pygmy dormice at Sparsholt College Hampshire, UK. An apple-wood climbing grid and three raised (at various heights above the substrate) woven-wicker nest boxes were provided. Instantaneous scan sampling was used to record 150 hours of nocturnal behavior (19:00 – 07:00 daily) over five experimental phases (Phase 1 baseline; Phase 2 climbing grid provided; Phase 3 lower nest box provided; Phase 4 middle nest box provided; Phase 5 higher nest box provided). Space use was determined using the modified Spread of Participation Index. Nest box use was recorded continually. The provision of the climbing grid significantly increased the groups’ time spent eating, digging, gnawing and climbing, and significantly decreased stereotypic scratching at glass. It also significantly changed the use of all enclosure zones, with mice utilizing the highest zones as soon as they were accessible. The addition of raised nesting opportunity saw the highest zones of the enclosure become those preferentially used. It also totally diminished stereotypic scratching at glass. The highest nest box was preferentially used and use of terrestrial nest boxes (those placed directly on top of the substrate) reduced significantly when raised alternatives were provided. This study suggests those working with African pygmy dormice should provide an enriched enclosure via ‘arboreal’ opportunity to increase active behaviors and reduce stereotypy

Ciliary tip actin dynamics regulate photoreceptor outer segment integrity

As signalling organelles, cilia regulate their G protein-coupled receptor content by ectocytosis, a process requiring localised actin dynamics to alter membrane shape. Photoreceptor outer segments comprise an expanse of folded membranes (discs) at the tip of highly-specialised connecting cilia, into which photosensitive GPCRs are concentrated. Discs are shed and remade daily. Defects in this process, due to mutations, cause retinitis pigmentosa (RP). Whilst fundamental for vision, the mechanism of photoreceptor disc generation is poorly understood. Here, we show membrane deformation required for disc genesis is driven by dynamic actin changes in a process akin to ectocytosis. We show RPGR, a leading RP gene, regulates actin-binding protein activity central to this process. Actin dynamics, required for disc formation, are perturbed in Rpgr mouse models, leading to aborted membrane shedding as ectosome-like vesicles, photoreceptor death and visual loss. Actin manipulation partially rescues this, suggesting the pathway could be targeted therapeutically. These findings help define how actin-mediated dynamics control outer segment turnover