On the use of SRIM for calculating arc-dpa exposure

We propose two methods for evaluating athermal recombination corrected (arc) displacement damage parameters in ion irradiations employing the computer code SRIM (Stopping and Range of Ions in Matter). The first method consists of post-processing the detailed SRIM output for all simulated damage events and re-calculating according to the arc damage model. In the second method, an approximate empirical formula is devised which gives the average displacements in the arc damage model as a function of the corresponding quantity according to the standard Norgett-Robinson-Torrens model, which is readily obtained from SRIM.Comment: 6 pages, 3 figure

Late acceleration and w=−1w=-1 crossing in induced gravity

We study the cosmological evolution on a brane with induced gravity within a bulk with arbitrary matter content. We consider a Friedmann-Robertson-Walker brane, invariantly characterized by a six-dimensional group of isometries. We derive the effective Friedmann and Raychaudhuri equations. We show that the Hubble expansion rate on the brane depends on the covariantly defined integrated mass in the bulk, which determines the energy density of the generalized dark radiation. The Friedmann equation has two branches, distinguished by the two possible values of the parameter \ex=\pm 1. The branch with \ex=1 is characterized by an effective cosmological constant and accelerated expansion for low energy densities. Another remarkable feature is that the contribution from the generalized dark radiation appears with a negative sign. As a result, the presence of the bulk corresponds to an effective negative energy density on the brane, without violation of the weak energy condition. The transition from a period of domination of the matter energy density by non-relativistic brane matter to domination by the generalized dark radiation corresponds to a crossing of the phantom divide $w=-1$.Comment: 7 pages, no figures, RevTex 4.0; (v2) new references are added, minor corrections and expanded discussion; (v3) additional comments at the end of section III, minor corrections and several new references are added, to match published version in Phys. Rev.

Dendritic Cells and Myeloid Derived Suppressor Cells Fully Responsive to Stimulation via Toll-Like Receptor 4 Are Rapidly Induced from Bone-Marrow Cells by Granulocyte-Macrophage Colony-Stimulating Factor

Dendritic cells (DCs) are commonly generated from bone marrow (BM) progenitor cells with granulocyte-macrophage colony-stimulating factor (GM-CSF) alone or in combination with interleukin 4 (IL-4). These cells are often harvested post day 5, when they acquire maturation markers and can stimulate T cells. Apart from DCs, myeloid derived suppressor cells (MDSCs) are also found within these cultures. However, little is known about the functional characteristics of DCs and MDSCs before day 5. Herein, using a murine model, it is shown that early DCs and MDSCs, even in cultures with GM-CSF alone, upregulate fully maturation and activation surface molecules in response to the toll-like receptor 4 (TLR4) ligand lipopolysaccharide (LPS) stimulation. Despite initially displaying lower marker expression levels, these cells efficiently induced T cell stimulation and cytokine production. Interestingly, Gr-1int MDSCs increased their T cell co-stimulatory activity upon TLR4 stimulation. Additionally, early DCs and MDSCs exhibited differential endocytic capacity for viral sized nanoparticles and bacterial sized microparticles. DCs internalized both particle sizes, whilst MDSCs only internalized the larger microparticles, with reduced endocytic activity over time in the culture. These findings have unveiled an important role for the rapid initiation of productive immunity by GM-CSF, with promising implications for future vaccine and DC immunotherapy developments

Simulation Modeling of Occupational Health of Tourism and Hospitality Workers

Tourism and hospitality research has utilized mostly traditional approaches to understand and explain observed phenomena. Complexity science offers great potential for studying the complex dynamical system of tourism and hospitality with greater effectiveness. The accelerating pace of technological advances, destabilization of societies, and increasing levels of uncertainty have fueled the emergence of chaos and complexity perspectives. Social scientists are increasingly viewing the conceptual and statistical assumptions underlying the linear paradigm as being seriously flawed and limiting our ability to explain social phenomena. Innovative complex-systems approaches grounded in complex adaptive systems (CAS) theoretical, methodological, and analytical perspectives have potential to lead to greater understanding of various phenomena. The foregoing methods and tools will be discussed in the context of occupational health of Hispanic immigrant hospitality sector workers

Preliminary results of investigations of possible ground deformation structures in the early christian basilica, ancient Lechaion harbour, Corinth, Greece.

Η Παλαιοχριστιανική Βασιλική Λεχαίου, Κόρινθος, κατασκευάστηκε στα τέλη του 5ου αι. μ.Χ. στον δυτικό βραχίονα του αρχαίου λιμανιού του Λεχαίου, και σύμφωνα με αρχαιολογικές ανασκαφές καταστράφηκε από την σεισμική δραστηριότητα του 551-552 μ.Χ.. Διάσπαρτα βυθίσματα και υβώματα που παρατηρήθηκαν στο δάπεδο της Βασιλικής αποτελούν ενδεικτικές δομές εδαφικής παραμόρφωσης η οποία πιθανόν να σχετίζεται με ρευστοποίηση εδάφους. Με στόχο την διερεύνηση της στρωματογραφίας και της δομής του υπεδάφους πραγματοποιήθηκαν γεωφυσικές διασκοπήσεις GPR και μετρήσεις αγωγιμότητας του εδάφους κατά μήκος δέκα επιλεγμένων τομών και συσχέτιση τους με τη στρωματογραφία όπως αυτή περιγράφεται από αρχαιολογικά σκάμματα. Τα αποτελέσματα της μελέτης είναι ενδεικτικά δομών παραμόρφωσης των υποκείμενων εδαφικών σχηματισμών με χαρακτηριστικά που επιτρέπουν την συσχέτιση των επιφανειακών δομών που παρατηρήθηκαν στο δάπεδο της Βασιλικής με το φαινόμενο της ρευστοποίησης εδάφους.The Early Christian Basilica of Lechaion, Corinth, located on the western jetty of the ancient Lechaion harbour, was constructed during the late 5th century AD and archaeological excavations suggest that it was destroyed by seismic activity during 551-552 AD. Numerous depressions and buckling structures observed on the Basilica floor are indicative of ground deformation structures, likely associated with liquefaction. In an attempt to investigate the subsurface soil structure, and stratigraphy, a GPR survey and horizontal distribution of ground conductivity along ten selected transects was carried out, supplemented by stratigraphic data as described by archaeological trenches. The results of the study revealed subsurface deformation features providing sufficient indications that allow us to suggest that the surface structures observed on the Basilica floor are the surface expression of earthquake-induced ground liquefaction

Self-similar Bianchi models: I. Class A models

We present a study of Bianchi class A tilted cosmological models admitting a proper homothetic vector field together with the restrictions, both at the geometrical and dynamical level, imposed by the existence of the simply transitive similarity group. The general solution of the symmetry equations and the form of the homothetic vector field are given in terms of a set of arbitrary integration constants. We apply the geometrical results for tilted perfect fluids sources and give the general Bianchi II self-similar solution and the form of the similarity vector field. In addition we show that self-similar perfect fluid Bianchi VII$_0$ models and irrotational Bianchi VI$_0$ models do not exist.Comment: 14 pages, Latex; to appear in Classical and Quantum Gravit

A geometric description of the intermediate behaviour for spatially homogeneous models

A new approach is suggested for the study of geometric symmetries in general relativity, leading to an invariant characterization of the evolutionary behaviour for a class of Spatially Homogeneous (SH) vacuum and orthogonal $\gamma -$law perfect fluid models. Exploiting the 1+3 orthonormal frame formalism, we express the kinematical quantities of a generic symmetry using expansion-normalized variables. In this way, a specific symmetry assumption lead to geometric constraints that are combined with the associated integrability conditions, coming from the existence of the symmetry and the induced expansion-normalized form of the Einstein's Field Equations (EFE), to give a close set of compatibility equations. By specializing to the case of a \emph{Kinematic Conformal Symmetry} (KCS), which is regarded as the direct generalization of the concept of self-similarity, we give the complete set of consistency equations for the whole SH dynamical state space. An interesting aspect of the analysis of the consistency equations is that, \emph{at least} for class A models which are Locally Rotationally Symmetric or lying within the invariant subset satisfying $N_{\alpha}^{\alpha}=0$, a proper KCS \emph{always exists} and reduces to a self-similarity of the first or second kind at the asymptotic regimes, providing a way for the ``geometrization'' of the intermediate epoch of SH models.Comment: Latex, 15 pages, no figures (uses iopart style/class files); added one reference and minor corrections; (v3) improved and extended discussion; minor corrections and several new references are added; to appear in Class. Quantum Gra

The influence of carbon on the resistivity recovery of proton irradiated Fe–11at.% Cr alloys

AbstractThe effect of carbon on the point defect migration properties in Fe–Cr alloys with a concentration of 11 at.% Cr is studied by means of resistivity recovery measurements after low temperature proton irradiation. The presence of carbon mainly affects features of the resistivity recovery spectra in the temperature ranges of (a) 150–200K, which are linked to self-interstitial defects, and (b) 400–500K, which are probably due to vacancy and vacancy-carbon complexes. The experimental results are discussed in terms of the possible interactions of carbon with radiation defects and its influence on solute atom re-ordering