6,185 research outputs found
Phase Transitions and Adsorption Isotherm in Multilayer Adsorbates with Lateral Interactions
We analyze here a model for an adsorbate system composed of many layers by
extending a theoretical approach used to describe pattern formation on a
monolayer of adsorbates with lateral interactions. The approach shows, in
addition to a first order phase transition in the first layer, a transition in
the second layer together with evidence of a "cascade" of transitions if more
layers are included. The transition profiles, showing a staircase structure,
corroborate this picture. The adsorption isotherm that came out of this
approach is in qualitative agreement with numerical and experimental results.Comment: Submited to Physica A, LaTex, 22 pgs, 6 figure
Regional variation in digital cushion pressure in the forefeet of horses and elephants
In this study, we seek to understand how the digital cushion morphologies evident in horse and elephant feet influence internal and external foot pressures. Our novel use of invasive blood pressure monitoring equipment, combined with a pressure pad and force plate, enabled measurements of (ex vivo) digital cushion pressure under increasing axial loads in seven horse and six elephant forefeet. Linear mixed effects models (LMER) revealed that internal digital cushion pressures increase under load and differ depending on region; elephant feet experienced higher magnitudes of medial digital cushion pressure, whereas horse feet experienced higher magnitudes of centralised digital cushion pressure. Direct comparison of digital cushion pressure magnitudes in both species, at equivalent loads relative to body weight, revealed that medial and lateral pressures increased more rapidly with load in elephant limbs. Within the same approximate region, internal pressures exceeded external, palmar pressures (on the sole of the foot), supporting previous Finite Element (FE) predictions. High pressures and large variations in pressure may relate to the development of foot pathology, which is a major concern in horses and elephants in a captive/domestic environment
Detection of Anomalous Microwave Emission in the Pleiades Reflection Nebula with WMAP and the COSMOSOMAS Experiment
We present evidence for anomalous microwave emission (AME) in the Pleiades
reflection nebula, using data from the seven-year release of the Wilkinson
Microwave Anisotropy Probe (WMAP) and from the COSMOSOMAS experiment. The flux
integrated in a 1-degree radius around R.A.=56.24^{\circ}, Dec.=23.78^{\circ}
(J2000) is 2.15 +/- 0.12 Jy at 22.8 GHz, where AME is dominant. COSMOSOMAS data
show no significant emission, but allow to set upper limits of 0.94 and 1.58 Jy
(99.7% C.L.) respectively at 10.9 and 14.7 GHz, which are crucial to pin down
the AME spectrum at these frequencies, and to discard any other emission
mechanisms which could have an important contribution to the signal detected at
22.8 GHz. We estimate the expected level of free-free emission from an
extinction-corrected H-alpha template, while the thermal dust emission is
characterized from infrared DIRBE data and extrapolated to microwave
frequencies. When we deduct the contribution from these two components at 22.8
GHz the residual flux, associated with AME, is 2.12 +/- 0.12 Jy (17.7-sigma).
The spectral energy distribution from 10 to 60 GHz can be accurately fitted
with a model of electric dipole emission from small spinning dust grains
distributed in two separated phases of molecular and atomic gas, respectively.
The dust emissivity, calculated by correlating the 22.8 GHz data with
100-micron data, is found to be 4.36+/-0.17 muK/MJy/sr, a value that is rather
low compared with typical values in dust clouds. The physical properties of the
Pleiades nebula indicate that this is indeed a much less opaque object than
others were AME has usually been detected. This fact, together with the broad
knowledge of the stellar content of this region, provides an excellent testbed
for AME characterization in physical conditions different from those generally
explored up to now.Comment: Accepted for publication in ApJ. 12 pages, 8 figure
Declarative Choreographies and Liveness
Part 1: Full PapersInternational audienceWe provide the first formal model for declarative choreographies, which is able to express general omega-regular liveness properties. We use the Dynamic Condition Response (DCR) graphs notation for both choreographies and end-points. We define end-point projection as a restriction of DCR graphs and derive the condition for end-point projectability from the causal relationships of the graph. We illustrate the results with a running example of a Buyer-Seller-Shipper protocol. All the examples are available for simulation in the online DCR workbench at http://dcr.tools/forte19
COSMOSOMAS Observations of the CMB and Galactic Foregrounds at 11 GHz: Evidence for anomalous microwave emission at high Galactic Latitude
We present observations with the new 11 GHz radiometer of the COSMOSOMAS
experiment at the Teide Observatory (Tenerife). The sky region between 0 deg <=
RA <= 360 deg and 26 deg <= DEC 49 deg (ca. 6500 square degrees) was observed
with an angular resolution of 0.9 deg. Two orthogonal independent channels in
the receiving system measured total power signals from linear polarizations
with a 2 GHz bandwidth. Maps with an average sensitivity of 50 microK per beam
have been obtained for each channel. At high Galactic latitude (|b|>30deg) the
11 GHz data are found to contain the expected cosmic microwave background as
well as extragalactic radiosources, galactic synchrotron and free-free
emission, and a dust-correlated component which is very likely of galactic
origin. At the angular scales allowed by the window function of the experiment,
the dust-correlated component presents an amplitude \Delta T aprox. 9-13 microK
while the CMB signal is of order 27 microK. The spectral behaviour of the
dust-correlated signal is examined in the light of previous COSMOSOMAS data at
13-17 GHz and WMAP data at 22-94 GHz in the same sky region. We detect a
flattening in the spectral index of this signal below 20 GHz which rules out
synchrotron radiation as being responsible for the emission. This anomalous
dust emission can be described by a combination of free-free emission and
spinning dust models with a flux density peaking around 20 GHz.Comment: 17 pages, 10 tables, 20 figures. Details on the COSMOSOMAS experiment
can be found at http://www.iac.es/project/cmb/cosmosomas
Uncovering the (un-)occupied electronic structure of a buried hybrid interface
The energy level alignment at organic/inorganic (o/i) semiconductor
interfaces is crucial for any light-emitting or -harvesting functionality.
Essential is the access to both occupied and unoccupied electronic states
directly at the interface, which is often deeply buried underneath thick
organic films and challenging to characterize. We use several complementary
experimental techniques to determine the electronic structure of
p-quinquephenyl pyridine (5P-Py) adsorbed on ZnO(10-10). The parent anchoring
group, pyridine, significantly lowers the work function by up to 2.9 eV and
causes an occupied in-gap state (IGS) directly below the Fermi level
. Adsorption of upright-standing 5P-Py also leads to a strong work
function reduction of up to 2.1 eV and to a similar IGS. The latter is then
used as an initial state for the transient population of three normally
unoccupied molecular levels through optical excitation and, due to its
localization right at the o/i interface, provides interfacial sensitivity, even
for thick 5P-Py films. We observe two final states above the vacuum level and
one bound state at around 2 eV above , which we attribute to the
5P-Py LUMO. By the separate study of anchoring group and organic dye combined
with the exploitation of the occupied IGS for selective interfacial
photoexcitation this work provides a new pathway for characterizing the
electronic structure at buried o/i interfaces
Beyond the pale?: the implications of the RSLG Report for non-CURL modern university libraries: Perspectives on the support libraries group: Final report
We have shown that the cluster-mass reconstruction method
which combines strong and weak gravitational lensing data, developed
in the first paper in the series, successfully reconstructs the
mass distribution of a simulated cluster. In this paper we apply the method to the
ground-based high-quality multi-colour data of RX J1347.5-114
Hafnium carbide formation in oxygen deficient hafnium oxide thin films
On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO)
contaminated with adsorbates of carbon oxides, the formation of hafnium carbide
(HfC) at the surface during vacuum annealing at temperatures as low as 600
{\deg}C is reported. Using X-ray photoelectron spectroscopy the evolution of
the HfC surface layer related to a transformation from insulating into
metallic state is monitored in situ. In contrast, for fully stoichiometric
HfO thin films prepared and measured under identical conditions, the
formation of HfC was not detectable suggesting that the enhanced adsorption
of carbon oxides on oxygen deficient films provides a carbon source for the
carbide formation. This shows that a high concentration of oxygen vacancies in
carbon contaminated hafnia lowers considerably the formation energy of hafnium
carbide. Thus, the presence of a sufficient amount of residual carbon in
resistive random access memory devices might lead to a similar carbide
formation within the conducting filaments due to Joule heating
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