4,367 research outputs found
The effects of Venus' thermal structure on buoyant magma ascent
The recent Magellan images have revealed a broad spatial distribution of surface volcanism on Venus. Previous work in modeling the ascent of magma on both Venus and Earth has indicated that the planetary thermal structure significantly influences the magmatic cooling rates and thus the amount of magma that can be transported to the surface before solidification. In order to understand which aspects of the thermal structure have the greatest influence on the cooling of ascending magma, we have constructed magma cooling curves for both plutonic and crack buoyant ascent mechanisms, and evaluated the curves for variations in the planetary mantle temperature, thermal gradient curvature with depth, surface temperature gradient, and surface temperature. The planetary thermal structure is modeled as T/T(sub 0) = 1-tau(1-Z/Z(sub 0)(exp n), where T is the temperature, T(sub 0) is the source depth temperature, tau = 1-(T(sub s)/T(sub 0)) where T(sub s) is the planetary surface temperature, Z is the depth, Z(sub 0) is the source depth, and n is a constant that controls thermal gradient curvature with depth. The equation is used both for mathematical convenience and flexibility, as well as its fit to the thermal gradients predicted by the cooling half-space models. We assume a constant velocity buoyant ascent, body-averaged magma temperatures and properties, an initially crystal-free magma, and the same liquidus and solidus for both Venus and Earth
Stabilization of nonlinear systems by similarity transformations
For a system x˙=A(x)+b(x)u, u(x)=s∗(x)x, x∈ℝn, where the pair
(A(x),b(x)) is given, we obtain the feedback vector s(x) to stabilize the
corresponding closed loop system. For an arbitrarily chosen constant
vector g, a sufficient condition of the existence and an explicit form of a
similarity transformation T(A(x),b(x),g) is established. The latter
transforms matrix A(x) into the Frobenius matrix, vector b(x) into g, and
an unknown feedback vector s(x) into the first unit vector. The boundaries
of A˜(y,g) are determined by the boundaries of {∂kA(x)∂xk,∂kb(x)∂xk}, k=0,n−1¯. The stabilization of the transformed system is subject to the
choice of the constant vector g
PHYCOERYTHROCYANINS FROM Westiellopsis prolifica AND Nostoc rivulare: CHARACTERIZATION OF THE PHYCOVIOLOBILIN CHROMOPHORE IN BOTH STATES
Phycoerythrocyanin or fractions enriched in it have been isolated from the filamentous cyanobacteria, Westiellopsis prolifica ARM 365 and Nostoc rivulare ARM 212. Both show the photoreversible photochromism (difference maxima at 503 and 570 nm) characteristic of this pigment, which is related to the phycoviolobilin chromophore on the α-subunit. Native phycoerythrocyanin and its β-subunit show little if any reversible photochemistry in the 600–620 nm region, where the phycocyanobilin chromophores absorb maximally. Instead the phycocyanobilin chromophores are bleached irreversibly. At the same time, the data show that reversible photochemistry is a useful analytical tool to detect phycoerythrocyanin in cyanobacterial extracts. Fluorescence measurements indicate that: (i) the 510 nm absorbing isomer of the violobilin chromophore has only little fluorescence; and (ii) the energy transfer from the violobilin chromophores to the cyanin chromophores is efficient only in the 570 nm form
Acceleration Profiles and Processing Methods for Parabolic Flight
Parabolic flights provide cost-effective, time-limited access to "weightless"
or reduced gravity conditions experienced in space or on planetary surfaces,
e.g. the Moon or Mars. These flights facilitate fundamental research - from
materials science to space biology - and testing/validation activities that
support and complement infrequent and costly access to space. While parabolic
flights have been conducted for decades, reference acceleration profiles and
processing methods are not widely available - yet are critical for assessing
the results of these activities. Here we present a method for collecting,
analyzing, and classifying the altered gravity environments experienced during
a parabolic flight. We validated this method using a commercially available
accelerometer during a Boeing 727-200F flight with parabolas. All data and
analysis code are freely available. Our solution can be easily integrated with
a variety of experimental designs, does not depend upon accelerometer
orientation, and allows for unsupervised and repeatable classification of all
phases of flight, providing a consistent and open-source approach to
quantifying gravito-intertial accelerations (GIA), or levels. As academic,
governmental, and commercial use of space increases, data availability and
validated processing methods will enable better planning, execution, and
analysis of parabolic flight experiments, and thus, facilitate future space
activities.Comment: Correspondence to C.E. Carr ([email protected]). 15 pages, 4 figures, 3
supplemental figures. Code: https://github.com/CarrCE/zerog, Dataset:
https://osf.io/nk2w4
Long-term variability of CO2 and O in the Mars upper atmosphere from MRO radio science data
We estimate the annual variability of CO2 and O partial density using approximately 6years of Mars Reconnaissance Orbiter (MRO) radio science data from August 2006 to January 2012, which cover three full Martian years (from the northern hemisphere summer of 28 to the northern hemisphere summer of 31). These two elements are the dominant species at the MRO periapsis altitude, constituting about 70-80% of the total density. We report the recovered annual cycle of CO2 and the annual and seasonal cycle of O in the upper atmosphere. Although no other observations are available at those altitudes, our results are in good agreement with the density measurements of the Mars Express Spectroscopy for Investigation of Characteristics of the Atmosphere of Mars, which uses stellar occultations between 60 and 130km to determine the CO2 variability, and with the Mars Global Reference Atmospheric Model 2010 for the O annual and seasonal variabilities. Furthermore, the updated model provides more reasonable MRO drag coefficients (CD), which are estimated to absorb mismodeling in the atmospheric density prediction. The higher content of dust in the atmosphere due to dust storms increases the density, so the CDs should compensate for this effect. The correlation between the drag coefficient and the dust optical depth, measured by the Mars Odyssey Thermal Emission Imaging System (THEMIS) instrument, increases from 0.4 to 0.8 with the a priori and adjusted models, respectively. The trend of CDs not only confirms a substantial improvement in the prediction of the atmospheric density with the updated model but also provides useful information for local dust storms, near MRO periapsis, that cannot be measured by the opacity level since THEMIS does not always sample the southern hemisphere evenly
On the Classification of Bulk and Boundary Conformal Field Theories
The classification of rational conformal field theories is reconsidered from
the standpoint of boundary conditions. Solving Cardy's equation expressing the
consistency condition on a cylinder is equivalent to finding integer valued
representations of the fusion algebra. A complete solution not only yields the
admissible boundary conditions but also gives valuable information on the bulk
properties.Comment: 7 pages, LaTeX; minor correction
Double Beta Decays into Excited States in Pd and Pd
A search for double beta decays of Pd and Pd into excited
states of the daughter nuclides has been performed using three ultra-low
background gamma-spectrometry measurements in the Felsenkeller laboratory,
Germany, the HADES laboratory, Belgium and at the LNGS, Italy. The combined
Bayesian analysis of the three measurements sets improved half-life limits for
the and decay modes of the ,
and transitions in Pd to yr,
yr and yr respectively and in Pd to
yr, yr and yr
respectively with 90% credibility
Lorentz and CPT Invariance Violation In High-Energy Neutrinos
High-energy neutrino astronomy will be capable of observing particles at both
extremely high energies and over extremely long baselines. These features make
such experiments highly sensitive to the effects of CPT and Lorentz violation.
In this article, we review the theoretical foundation and motivation for CPT
and Lorentz violating effects, and then go on to discuss the related
phenomenology within the neutrino sector. We describe several signatures which
might be used to identify the presence of CPT or Lorentz violation in next
generation neutrino telescopes and cosmic ray experiments. In many cases,
high-energy neutrino experiments can test for CPT and Lorentz violation effects
with much greater precision than other techniques.Comment: 27 pages, 8 figure
Model Pendidikan Partisipatif Empat Pilar Bangsa Bagi Integrasi Nasional
This study aims to develop a participatory education model for educating four nation pillars in grassroots level. The research was concluded in Sudiroprajan Surakarta using participatory action research. The result shows that throught mural citizen can express their understanding of four nation pillars concern on the form of mural drawings and writings indicate that they understanding the content and practice the four nation pillars (Pancasila, the 1945 Constitution, Unity in Diversity, The Unity State Republic of Indonesia) in the everyday life. The murals do not only make the walls clean and pleasing. They also can actualize the message of natural assimilation. This is illustrated in Mbalong mural which suggests an idea that ethnicity there, is not longer a problem, that they can reduce primordial ties, strengthen unity, nationalism, and the national integration. © 2013 Universitas Negeri Semaran
The Relationship between the UniProt Knowledgebase (UniProtKB) and the IntAct Molecular Interaction Databases
IntAct provides a freely available, open source database system and analysis tools for protein interaction data. All interactions are derived from literature curation or direct user submission and all experimental information relating to binary protein-protein
interactions is entered into the IntAct database by curators, via a web-based editor. Interaction information is added to the SUBUNIT comment and the RP line of the relevant publication within the UniProtKB entry. There may be a single INTERACTION comment present within a UniProtKB entry, which conveys information relevant to binary protein-protein interactions. This is automatically derived from the IntAct database and is updated on a triweekly basis. Interactions can be derived by any appropriate experimental method but must be confirmed by a second interaction if resulting from a single yeast2hybrid experiment. For large-scale experiments, interactions are considered if a high confidence score is assigned by the authors. The INTERACTION line contains a direct link to IntAct that provides detailed information for the experimental support. These lines are not changed manually and any discrepancy is reported to IntAct for updates. There is also a database crossreference line within the UniProtKB entry i.e.: DR IntAct _UniProtKB AC, which directs the user to additional interaction data for that molecule. 
UniProt is supported by grants from the National Institutes of Health, European Commission, Swiss Federal Government and PATRIC BRC.
IntAct is funded by the European Commission under FELICS, contract number 021902 (RII3) within the Research Infrastructure Action of the FP6 "Structuring the European Research Area" Programme
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