1,961 research outputs found
Dynamical phase transition of a 1D transport process including death
Motivated by biological aspects related to fungus growth, we consider the
competition of growth and corrosion. We study a modification of the totally
asymmetric exclusion process, including the probabilities of injection
and death of the last particle . The system presents a phase transition
at , where the average position of the last particle
grows as . For , a non equilibrium stationary state
exists while for the asymptotic state presents a low density
and max current phases. We discuss the scaling of the density and current
profiles for parallel and sequential updates.Comment: 4 pages, 5 figure
Gap opening in the zeroth Landau level in gapped graphene: Pseudo-Zeeman splitting in an angular magnetic field
We present a theoretical study of gap opening in the zeroth Landau level in
gapped graphene as a result of pseudo-Zeeman interaction. The applied magnetic
field couples with the valley pseudospin degree of freedom of the charge
carriers leading to the pseudo-Zeeman interaction. To investigate its role in
transport at the Charge Neutrality Point (CNP), we study the integer quantum
Hall effect (QHE) in gapped graphene in an angular magnetic field in the
presence of pseudo-Zeeman interaction. Analytical expressions are derived for
the Hall conductivity using Kubo-Greenwood formula. We also determine the
longitudinal conductivity for elastic impurity scattering in the first Born
approximation. We show that pseudo-Zeeman splitting leads to a minimum in the
collisional conductivity at high magnetic fields and a zero plateau in the Hall
conductivity. Evidence for activated transport at CNP is found from the
temperature dependence of the collisional conductivity.Comment: 20 pages, 4 figures, Accepted in J. Phys. Condensed matte
H2O Maser Polarization of the Water Fountains IRAS 15445-5449 and IRAS 18043-2116
We present the morphology and linear polarization of the 22-GHz H2O masers in
the high-velocity outflow of two post-AGB sources, d46 (IRAS 15445-5449) and
b292 (IRAS 18043-2116). The observations were performed using The Australia
Telescope Compact Array. Different levels of saturated maser emission have been
detected for both sources. We also present the mid-infrared image of d46
overlaid with the distribution of the maser features that we have observed in
the red-shifted lobe of the bipolar structure. The relative position of the
observed masers and a previous radio continuum observation suggests that the
continnum is produced along the blue-shifted lobe of the jet. It is likely due
to synchrontron radiation, implying the presence of a strong magnetic field in
the jet. The fractional polarization levels measured for the maser features of
d46 indicate that the polarization vectors are tracing the poloidal component
of the magnetic field in the emitting region. For the H2O masers of b292 we
have measured low levels of fractional linear polarization. The linear
polarization in the H2O maser region of this source likely indicates a dominant
toroidal or poloidal magnetic field component. Since circular polarization was
not detected it is not possible to determine the magnetic field strength.
However, we present a 3-sigma evaluation of the upper limit intensity of the
magnetic field in the maser emitting regions of both observed sources.Comment: 7 pages, 4 figures, 1 table. To be published in Monthly Notices of
the Royal Astronomical Societ
Preparation and Anti-Tumour Activity of Some Arylbismuth(III) Oxine Complexes
New arylbismuth(lll) oxinates, PhBi(MeOx)2, (p-MeC6H4)Bi(Ox)2, (p-MeC6H4)Bi(MeOx)2, (p-ClC6H4)Bi(Ox)2, and (p-ClC6H4)Bi(MeOx)2 (Ox− = quinolin-8-olate and MeOx−=2-methylquinolin-8-olate) have been prepared by reaction of the appropriate diarylbismuth chlorides with Na(Ox) or Na(MeOx) in the presence of 15-crown-5. An X-ray crystallographic study has shown
PhBi(MeOx)2 to be a five coordinate monomer with distorted square pyramidal stereochemistry.
Chelating MeOx ligands have a cisoid arrangement in the square plane and the phenyl group is
apical. The lattice is stabilised by significant π-π interactions between centrosymmetric molecules.
A range of these complexes has been shown to have high in vitro biological activity
(comparable with or better than cisplatin) against L1210 leukaemia, the corresponding cisplatin
resistant line, and a human ovarian cell line, SKOV-3. However, initial in vivo testing against a solid
mouse plasmacytoma (PC6) and P388 leukaemia has not revealed significant activity
Dynamic changes in cellular infiltrates with repeated cutaneous vaccination: a histologic and immunophenotypic analysis
<p>Abstract</p> <p>Background</p> <p>Melanoma vaccines have not been optimized. Adjuvants are added to activate dendritic cells (DCs) and to induce a favourable immunologic milieu, however, little is known about their cellular and molecular effects in human skin. We hypothesized that a vaccine in incomplete Freund's adjuvant (IFA) would increase dermal Th1 and Tc1-lymphocytes and mature DCs, but that repeated vaccination may increase regulatory cells.</p> <p>Methods</p> <p>During and after 6 weekly immunizations with a multipeptide vaccine, immunization sites were biopsied at weeks 0, 1, 3, 7, or 12. In 36 participants, we enumerated DCs and lymphocyte subsets by immunohistochemistry and characterized their location within skin compartments.</p> <p>Results</p> <p>Mature DCs aggregated with lymphocytes around superficial vessels, however, immature DCs were randomly distributed. Over time, there was no change in mature DCs. Increases in T and B-cells were noted. Th2 cells outnumbered Th1 lymphocytes after 1 vaccine 6.6:1. Eosinophils and FoxP3<sup>+ </sup>cells accumulated, especially after 3 vaccinations, the former cell population most abundantly in deeper layers.</p> <p>Conclusions</p> <p>A multipeptide/IFA vaccine may induce a Th2-dominant microenvironment, which is reversed with repeat vaccination. However, repeat vaccination may increase FoxP3<sup>+</sup>T-cells and eosinophils. These data suggest multiple opportunities to optimize vaccine regimens and potential endpoints for monitoring the effects of new adjuvants.</p> <p>Trail Registration</p> <p>ClinicalTrials.gov Identifier: NCT00705640</p
Diversity, competition, extinction: the ecophysics of language change
As early indicated by Charles Darwin, languages behave and change very much
like living species. They display high diversity, differentiate in space and
time, emerge and disappear. A large body of literature has explored the role of
information exchanges and communicative constraints in groups of agents under
selective scenarios. These models have been very helpful in providing a
rationale on how complex forms of communication emerge under evolutionary
pressures. However, other patterns of large-scale organization can be described
using mathematical methods ignoring communicative traits. These approaches
consider shorter time scales and have been developed by exploiting both
theoretical ecology and statistical physics methods. The models are reviewed
here and include extinction, invasion, origination, spatial organization,
coexistence and diversity as key concepts and are very simple in their defining
rules. Such simplicity is used in order to catch the most fundamental laws of
organization and those universal ingredients responsible for qualitative
traits. The similarities between observed and predicted patterns indicate that
an ecological theory of language is emerging, supporting (on a quantitative
basis) its ecological nature, although key differences are also present. Here
we critically review some recent advances lying and outline their implications
and limitations as well as open problems for future research.Comment: 17 Pages. A review on current models from statistical Physics and
Theoretical Ecology applied to study language dynamic
Spectroscopy of the odd-odd fp-shell nucleus 52Sc from secondary fragmentation
The odd-odd fp-shell nucleus 52Sc was investigated using in-beam gamma-ray
spectroscopy following secondary fragmentation of a 55V and 57Cr cocktail beam.
Aside from the known gamma-ray transition at 674(5)keV, a new decay at
E_gamma=212(3) keV was observed. It is attributed to the depopulation of a
low-lying excited level. This new state is discussed in the framework of
shell-model calculations with the GXPF1, GXPF1A, and KB3G effective
interactions. These calculations are found to be fairly robust for the
low-lying level scheme of 52Sc irrespective of the choice of the effective
interaction. In addition, the frequency of spin values predicted by the shell
model is successfully modeled by a spin distribution formulated in a
statistical approach with an empirical, energy-independent spin-cutoff
parameter.Comment: accepted for publication in PR
Locating regional health policy: Institutions, politics, and practices
Poverty reduction and health became central in the agendas of Southern regional organisations in the last two decades. Yet, little is known about how these organisations address poverty, inclusion and social inequality, and how Southern regional formations are engaging in power constellations, institutions, processes, interests and ideological positions within different spheres of governance. This article reviews academic literatures spanning global social policy, regional studies and diplomacy studies, and the state of knowledge and understanding of the ‘place’ of regional actors in health governance as a global political practice therein. It identifies theoretical and thematic points of connection between disparate literatures and how these can be bridged through research focusing on the social policies of regional organisations and regional integration processes. This framework hence locates the contributions of each of the research articles of this Special Issue of Global Social Policy on the regional dimension of health policy and diplomacy in relation to Southern Africa and South America. It also highlights the ways in which the articles bring new evidence about how social relations of welfare are being (re)made over larger scales and how regional actors may initiate new norms to improve health rights in international arenas engaging in new forms of ‘regional’ diplomacy
3d-4f heterometallic complexes by the reduction of transition metal carbonyls with bulky Ln amidinates
The redox chemistry between divalent lanthanide complexes bearing bulky amidinate ligands has been studied with 3d transition metal carbonyl complexes (iron and cobalt). The reaction of [(DippForm)Sm(thf)] (DippForm = N,N′-bis(2,6-diisopropylphenyl)formamidinate) with [Co(CO)] resulted in the formation of a tetranuclear Sm–Co complex, [{(DippForm)Sm(thf)}{(μ-CO)Co(CO)}]. The product of the reaction of [(DippForm)Yb(thf)] and [Co(CO)] gives the dinuclear Yb–Co complex [{(DippForm)Yb(thf)}{(μ-CO)Co(CO)}] in toluene. The reaction of [(DippForm)Sm(thf)] was also carried with the neighbouring group 8 carbonyl complexes [Fe(CO)] and [Fe(CO)], resulting in a pentanuclear Sm–Fe complex, [{(DippForm)Sm}{(μ-CO)Fe(CO)}], featuring a triangular iron carbonyl cluster core
Dynactin is required for bidirectional organelle transport
Kinesin II is a heterotrimeric plus end–directed microtubule motor responsible for the anterograde movement of organelles in various cell types. Despite substantial literature concerning the types of organelles that kinesin II transports, the question of how this motor associates with cargo organelles remains unanswered. To address this question, we have used Xenopus laevis melanophores as a model system. Through analysis of kinesin II–mediated melanosome motility, we have determined that the dynactin complex, known as an anchor for cytoplasmic dynein, also links kinesin II to organelles. Biochemical data demonstrates that the putative cargo-binding subunit of Xenopus kinesin II, Xenopus kinesin II–associated protein (XKAP), binds directly to the p150Glued subunit of dynactin. This interaction occurs through aa 530–793 of XKAP and aa 600–811 of p150Glued. These results reveal that dynactin is required for transport activity of microtubule motors of opposite polarity, cytoplasmic dynein and kinesin II, and may provide a new mechanism to coordinate their activities
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