123 research outputs found
SensX: About Sensing and Assessment of Complex Human Motion
The great success of wearables and smartphone apps for provision of extensive
physical workout instructions boosts a whole industry dealing with consumer
oriented sensors and sports equipment. But with these opportunities there are
also new challenges emerging. The unregulated distribution of instructions
about ambitious exercises enables unexperienced users to undertake demanding
workouts without professional supervision which may lead to suboptimal training
success or even serious injuries. We believe, that automated supervision and
realtime feedback during a workout may help to solve these issues. Therefore we
introduce four fundamental steps for complex human motion assessment and
present SensX, a sensor-based architecture for monitoring, recording, and
analyzing complex and multi-dimensional motion chains. We provide the results
of our preliminary study encompassing 8 different body weight exercises, 20
participants, and more than 9,220 recorded exercise repetitions. Furthermore,
insights into SensXs classification capabilities and the impact of specific
sensor configurations onto the analysis process are given.Comment: Published within the Proceedings of 14th IEEE International
Conference on Networking, Sensing and Control (ICNSC), May 16th-18th, 2017,
Calabria Italy 6 pages, 5 figure
The Evolution of Density Structure of Starless and Protostellar Cores
We present a near-infrared extinction study of nine dense cores at
evolutionary stages between starless to Class I. Our results show that the
density structure of all but one observed cores can be modeled with a single
power law rho \propto r^p between ~ 0.2R-R of the cores. The starless cores in
our sample show two different types of density structures, one follows p ~ -1.0
and the other follows p ~ -2.5, while the protostellar cores all have p ~ -2.5.
The similarity between the prestellar cores with p ~ -2.5 and protostellar
cores implies that those prestellar cores could be evolving towards the
protostellar stage. The slope of p ~ -2.5 is steeper than that of an singular
isothermal sphere, which may be interpreted with the evolutionary model of
cores with finite mass.Comment: 19 pages, 3 figures, accepted for publication in the Astrophysical
Journa
Density and Temperature Structure of TMC-1C from 450 and 850 micron Maps
We have mapped the central 10'x10' of the dense core TMC-1C at 450 and 850
microns using SCUBA on the James Clerk Maxwell Telescope. The unusually high
quality of the 450 micron map allows us to make a detailed analysis of the
temperature and column density profiles of the core. We find that the dust
temperature at the center of TMC-1C is 7 K, rising to 11 K at the edges. We
discuss the possibility and effects of a variable emissivity spectral index on
the derived mass profile. The low dust temperature of TMC-1C results in a high
derived mass for the core, significantly larger than the virial mass estimated
from the linewidth of the N2H+ (1-0) transition. This result is valid within a
wide range of dust properties and ellipticities of the core. The N2H+ (1-0)
spectra, taken with the IRAM 30m telescope, show signs of self-absorption,
which provide evidence of sub-sonic infall motions. The derived density profile
and infall velocity is compared to the predictions of several popular star
formation models, and the Bonnor-Ebert model isthe best fit analytic model.Comment: 38 pages, 13 Figures, accepted to Ap
Tracing the Mass during Low-Mass Star Formation. II. Modelling the Submillimeter Emission from Pre-Protostellar Cores
We have modeled the emission from dust in pre-protostellar cores, including a
self-consistent calculation of the temperature distribution for each input
density distribution. Model density distributions include Bonnor-Ebert spheres
and power laws. The Bonnor-Ebert spheres fit the data well for all three cores
we have modeled. The dust temperatures decline to very low values (\Td \sim 7
K) in the centers of these cores, strongly affecting the dust emission.
Compared to earlier models that assume constant dust temperatures, our models
indicate higher central densities and smaller regions of relatively constant
density. Indeed, for L1544, a power-law density distribution, similar to that
of a singular, isothermal sphere, cannot be ruled out. For the three sources
modeled herein, there seems to be a sequence of increasing central
condensation, from L1512 to L1689B to L1544. The two denser cores, L1689B and
L1544, have spectroscopic evidence for contraction, suggesting an evolutionary
sequence for pre-protostellar cores.Comment: 22 pages, 9 figures, Ap. J. accepted, uses emulateapj5.st
Magnetically Controlled Spasmodic Accretion During Star Formation. I. Formulation of the Problem and Method of Solution
We formulate the problem of the late accretion phase of the evolution of an
isothermal magnetic disk surrounding a forming star. The evolution is described
by the six-fluid MHD equations, accounting for the presence of neutrals, atomic
and molecular ions, electrons, and neutral, positively, and negatively charged
grains. Only the electron fluid is assumed to be attached to the magnetic
field, in order to investigate the effect of the detachment of the ions from
the magnetic field lines that begins at densities as low as 10^8 cm^-3. The
"central sink approximation" is used to circumvent the problem of describing
the evolution inside the opaque central region for densities greater than 10^11
cm^-3. In this way, the structure and evolution of the isothermal disk
surrounding the forming star can be studied at late times without having to
implement the numerically costly radiative transfer required by the physics of
the opaque core. The mass and magnetic flux accumulating in the forming star
arecalculated, as are their effects on the structure & evolution of the
surrounding disk. The numerical method of solution first uses an adaptive grid
and later, after a central region a few AU in radius becomes opaque, switches
to a stationary but nonuniform grid with a central sink cell. It also involves
an implicit time integrator, an advective difference scheme that possesses the
transportive property, a second-order difference approximation of forces inside
a cell, an integral approximation of the gravitational and magnetic fields, and
tensor artificial viscosity that permits an accurate investigation of the
formation and evolution of shocks in the neutral fluid.Comment: Astrophysical Journal, in press. 32 page
Ermittlung des Verbrauchs biogener Festbrennstoffe im Sektor Gewerbe,Handel, Dienstleistungen (GHD-Sektor)
Die Politik hat sich sowohl auf nationaler als auch auf europäischer Ebene ambitionierte Ziele zum Ausbau erneuerbarer Energien und zur Minderung der Treibhausgasemissionen gesetzt. Im Nationalen Aktionsplan für Erneuerbare Energien der Bundesrepublik Deutschland sind diese Ziele bis zum Jahr 2020 definiert. Der Anteil erneuerbarer Energien bei der Bereitstellung von Wärme und Kälte soll demnach von 6,6 % auf 15,5 % des Bruttoendenergieverbrauches steigen. Entsprechend der zunehmenden Bedeutung der solarthermischen, oberflächennahen und geothermischen Wärme wird der relative Anteil der Biomasse abnehmen. Mit den im Nationalen Aktionsplan aufgeführten 79 % leistet sie dennoch einen essentiellen Betrag im regenerativen Wärmemarkt [BMU 2010]. [... aus der Einleitung
Invasion thresholds and the evolution of nonequilibrium virulence
The enterprise of virulence management attempts to predict how social practices and other factors affect the evolution of parasite virulence. These predictions are often based on parasite optima or evolutionary equilibria derived from models of host-parasite dynamics. Yet even when such models accurately capture the parasite optima, newly invading parasites will typically not be at their optima. Here we show that parasite invasion of a host population can occur despite highly nonoptimal virulence. Fitness improvements soon after invasion may proceed through many steps with wide changes in virulence, because fitness depends on transmission as well as virulence, and transmission improvements can overwhelm nonoptimal virulence. This process is highly sensitive to mutation supply and the strength of selection. Importantly, the same invasion principle applies to the evolution of established parasites, whenever mutants arise that overcome host immunity/resistance. A host population may consequently experience repeated invasions of new parasite variants and possible large shifts in virulence as it evolves in an arms race with the parasite. An experimental study of phage lysis time and examples of mammalian viruses matching some of these characteristics are reviewed
Soft Photon Problem in Leptonic B-decays
We point out at the peculiarity of B --> mu nu decay, namely the enhancement
of the soft photon events which originate from the structure dependent part of
the B --> mu nu gamma amplitude. This may be a dominant source of systematic
uncertainty and compromise the projected experimental uncertainty on Gamma(B
--> mu nu). We show that the effect of these soft photons can be controlled if
the experimental cut on identification of soft photons is lowered and
especially if the better resolution in identifying the momentum of muon
emerging from B --> mu nu, is made. A lattice QCD computation of the relevant
form factors would be highly helpful for a better numerical control over the
structure dependent soft photon emission.Comment: 16 pages, 3 figure
Resolved images of self-gravitating circumstellar discs with ALMA
In this paper we present simulated observations of massive self-gravitating
circumstellar discs using the Atacama Large Millimetre/sub-millimetre Array
(ALMA). Using a smoothed particle hydrodynamics model of a disc
orbiting a protostar, with a cooling model appropriate for discs
at temperatures below K and representative dust opacities, we have
constructed maps of the expected emission at sub-mm wavelengths. We have then
used the CASA ALMA simulator to generate simulated images and visibilities with
various array configurations and observation frequencies, taking into account
the expected thermal noise and atmospheric opacities. We find that at 345 GHz
(870 m) spiral structures at a resolution of a few AU should be readily
detectable in approximately face-on discs out to distances of the Taurus-Auriga
star-forming complex.Comment: 8 pages, 6 figures, accepted to MNRAS. Figure quality degraded. Full
paper with higher quality figures available at
http://www2.fisica.unimi.it/lodato/CossinsLodatoTesti1.pd
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