74 research outputs found
Remote Sensing Analyses of Neotectonic Active Regions in East-Kamchatka
The tectonic history of the Kamchatka
Peninsula is dominated by continuous
accumulation and amalgamation of terranes
with different origins, which were
delivered by convergence between the
Pacific plate and in former times, the
Kula plate against Eurasia (Freitag,
2002). The Kronotsky and Cape Kamchatka
Peninsulas show that the collision
of terranes and the resulting tectonics
are still important for major parts of
East-Kamchatka. While the collision of
the Kronotsky Peninsula is sorely influenced
by the convergence of the Pacific
plate, the Cape Kamchatka Peninsula is
affected by the collision of the Aleutian
Arc with Kamchatka, what gives the opportunity to compare two different processes that resulted in the amalgamation
of terranes to Kamchatka.conferenc
Use and Reporting of Patient-Reported Outcomes in Trials of Palliative Radiotherapy: A Systematic Review
Two authors independently assessed eligibility. Trial characteristics were extracted and standard of PRO reporting was assessed in adherence to the Consolidated Standards of Reporting Trials (CONSORT) PRO extension. The association of the year of publication with the use of PROs was assessed by logistic regression. Factors associated with higher CONSORT-PRO adherence were analyzed by multiple regression. This study is reported following the PRISMA guidelines.Among 7377 records screened, 225 published clinical trials representing 24 281 patients were eligible. Of these, 45 trials (20%) used a PRO as a primary end point and 71 trials (31%) used a PRO as a secondary end point. The most prevalent PRO measures were the Numeric Rating Scale/Visual Analogue Scale (38 trials), European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire C30 (32 trials), and trial-specific unvalidated measures (25 trials). A more recent year of publication was significantly associated with a higher chance of PROs as a secondary end point (odds ratio [OR], 1.04 [95% CI, 1.00-1.07]; P = .03) but not as primary end point. Adherence to CONSORT-PRO was poor or moderate for most items. Mean (SD) adherence to the extension adherence score was 46.2% (19.6%) for trials with PROs as primary end point and 31.8% (19.8%) for trials with PROs as a secondary end point. PROs as a primary end point (regression coefficient, 9.755 [95% CI, 2.270-17.240]; P = .01), brachytherapy as radiotherapy modality (regression coefficient, 16.795 [95% CI, 5.840-27.751]; P = .003), and larger sample size (regression coefficient, 0.028 [95% CI, 0.006-0.049]; P = .01) were significantly associated with better PRO reporting per extension adherence score. Conclusions and relevance In this systematic review of palliative radiotherapy trials, the use and reporting of PROs had room for improvement for future trials, preferably with PROs as a primary end point
A comprehensive set of simulations of high-velocity collisions between main sequence stars
We report on a very large set of simulations of collisions between two main
sequence (MS) stars. These computations were done with the ``Smoothed Particle
Hydrodynamics'' method. Realistic stellar structure models for evolved MS stars
were used. In order to sample an extended domain of initial parameters space
(masses of the stars, relative velocity and impact parameter), more than 15000
simulations were carried out. We considered stellar masses ranging between 0.1
and 75 Msun and relative velocities up to a few thousands km/s. To limit the
computational burden, a resolution of 2000-30000 particles per star was used.
The primary goal of this study was to build a complete database from which the
result of any collision can be interpolated. This allows us to incorporate the
effects of stellar collisions with an unprecedented level of realism into
dynamical simulations of galactic nuclei and other dense stellar clusters. We
make the data describing the initial condition and outcome (mass and energy
loss, angle of deflection) of all our simulations freely available on the
Internet. We find that the outcome of collisions depends sensitively on the
stellar structure and that, in most cases, using polytropic models is
inappropriate. Published fitting formulas for the collision outcomes,
established from a limited set of collisions, prove of limited use because they
do not allow robust extrapolation to other stellar structures or relative
velocities.Comment: 45 pages, 44 figures. Modified to reflect the changes in the
published version (MNRAS). PDF version with high-res figures at
http://obswww.unige.ch/~freitag/papers/article_collisions.pdf, simulation
data at http://obswww.unige.ch/~freitag/MODEST_WG4/FB_Collision_Data/, movies
at http://obswww.unige.ch/~freitag/collisions/animations/index.htm
Targeted adenovirus-mediated transduction of human T cells in vitro and in vivo
Clinical success in T cell therapy has stimulated widespread efforts to increase safety and potency and to extend this technology to solid tumors. Yet progress in cell therapy remains restricted by the limited payload capacity, specificity of target cell transduction, and transgenic gene expression efficiency of applied viral vectors. This renders complex reprogramming or direct in vivo applications difficult. Here, we developed a synergistic combination of trimeric adapter constructs enabling T cell-directed transduction by the human adenoviral vector serotype C5 in vitro and in vivo. Rationally chosen binding partners showed receptor-specific transduction of otherwise non-susceptible human T cells by exploiting activation stimuli. This platform remains compatible with high-capacity vectors for up to 37 kb DNA delivery, increasing payload capacity and safety because of the removal of all viral genes. Together, these findings provide a tool for targeted delivery of large payloads in T cells as a potential avenue to overcome current limitations of T cell therapy
Smoothed Particle Hydrodynamics simulations of white dwarf collisions and close encounters
The collision of two white dwarfs is a quite frequent event in dense stellar
systems, like globular clusters and galactic nuclei. In this paper we present
the results of a set of simulations of the close encounters and collisions of
two white dwarfs. We use an up- to-date smoothed particle hydrodynamics code
that incorporates very detailed input physics and an improved treatment of the
artificial viscosity. Our simulations have been done using a large number of
particles (~ 4 \times 10^5) and covering a wide range of velocities and initial
distances of the colliding white dwarfs. We discuss in detail when the initial
eccentric binary white dwarf survives the closest approach, when a lateral
collision in which several mass transfer episodes occur is the outcome of the
newly formed binary system, and which range of input parameters leads to a
direct collision, in which only one mass transfer episode occurs. We also
discuss the characteristics of the final configuration and we assess the
possible observational signatures of the merger, such as the associated
gravitational waveforms and the fallback luminosities. We find that the overall
evolution of the system and the main characteristics of the final object agree
with those found in previous studies. We also find that the fallback
luminosities are close to 10^48 erg/s. Finally, we find as well that in the
case of lateral and direct collisions the gravitational waveforms are
characterized by large-amplitude peaks which are followed by a ring-down phase,
while in the case in which the binary white dwarf survives the closest
approach, the gravitational pattern shows a distinctive behavior, typical of
eccentric systems.Comment: 16 pages, 12 figures. Accepted for publication in MNRA
Deformationsanalyse und mechanische Kopplung eines aktiven fore-arcs in Raum und Zeit, Kamtschatka, Russische Föderation
Seit dem Mesozoikum wächst die kontinentale
Kruste am aktiven Plattenrand
von Kamtschatka durch Akkretion
allochthoner Terrane. Dieses Wachstum
manifestiert sich in der differenziellen
Exhumierung und Hebung tektonischer
Blöcke innerhalb des Akkretionskeils,
parallel zum Kamtschatka-
Graben. Die Kinematik der Exhumierung
soll mittels strukturgeologischer
und neotektonischer Deformationsanalyse
erfasst und mit thermochronologischen
Untersuchungen an Apatiten bis
etwa ins Untere Pliozän quantifiziert
werden.conferenc
Dynamical Processes in Globular Clusters
Globular clusters are among the most congested stellar systems in the
Universe. Internal dynamical evolution drives them toward states of high
central density, while simultaneously concentrating the most massive stars and
binary systems in their cores. As a result, these clusters are expected to be
sites of frequent close encounters and physical collisions between stars and
binaries, making them efficient factories for the production of interesting and
observable astrophysical exotica. I describe some elements of the competition
among stellar dynamics, stellar evolution, and other processes that control
globular cluster dynamics, with particular emphasis on pathways that may lead
to the formation of blue stragglers.Comment: Chapter 10, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G.
Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe
The dynamical formation of LMXBs in dense stellar environments: globular clusters and the inner bulge of M31
The radial distribution of luminous L_X>10^{36} erg/s X-ray point sources in
the bulge of M31 is investigated using archival Chandra observations. We find a
significant increase of the specific frequency of X-ray sources, per unit
stellar mass, within 1 arcmin from the centre of the galaxy. The radial
distribution of surplus sources in this region follows the density squared law,
suggesting that they are low-mass X-ray binaries formed dynamically in the
dense inner bulge. We investigate dynamical formation of LMXBs, paying
particular attention to the high velocity regime characteristic for galactic
bulges, which has not been explored previously. Our calculations suggest that
the majority of the surplus sources are formed in tidal captures of black holes
by main sequence stars of low mass, M<0.3-0.4 M_sol, with some contribution of
NS systems of same type. Due to the small size of the accretion discs a
fraction of such systems may be persistent X-ray sources. Some of sources may
be ultra-compact X-ray binaries with helium star/white dwarf companions. We
also predict a large number of faint transients, both NS and BH systems, within
1 arcmin from the M31 galactic centre. Finally, we consider the population of
dynamically formed binaries in Galactic globular clusters, emphasizing the
differences between these two types of stellar environmentsComment: 18 pages, published in MNRA
Stellar Processes Near the Massive Black Hole in the Galactic Center
A massive black hole resides in the center of most, perhaps all galaxies. The
one in the center of our home galaxy, the Milky Way, provides a uniquely
accessible laboratory for studying in detail the connections and interactions
between a massive black hole and the stellar system in which it grows; for
investigating the effects of extreme density, velocity and tidal fields on
stars; and for using stars to probe the central dark mass and probe
post-Newtonian gravity in the weak- and strong-field limits. Recent results,
open questions and future prospects are reviewed in the wider context of the
theoretical framework and physical processes that underlie them.
Contents: [1] Introduction (1.1) Astrophysical context (1.2) Science
questions (1.3) Scope and connections to related topics [2] Observational
overview: Stars in the Galactic center (2.1) The central 100 parsecs (2.2) The
central parsec [3] Stellar dynamics at extreme densities (3.1) Physical
processes and scales (3.2) The stellar cusp in the Galactic center (3.3) Mass
segregation (3.4) Stellar Collisions [4] Probing the dark mass with stellar
dynamics (4.1) Weighing and pinpointing the dark mass (4.2) Constraints on
non-BH dark mass alternatives (4.3) Limits on MBH binarity (4.4) High-velocity
runaway stars [5] Probing post-Newtonian gravity near the MBH (5.1)
Relativistic orbital effects (5.2) Gravitational lensing [6] Strong star-MBH
interactions (6.1) Tidal disruption (6.2) Dissipative interactions with the MBH
[7] The riddle of the young stars (7.1) The difficulties of forming or
importing stars near a MBH (7.2) Proposed solutions (7.3) Feeding the MBH with
stellar winds [8] Outlook (8.1) Progress report (8.2) Future directionsComment: Invited review article, to appear in Physics Reports. 101 p
- …