30,438 research outputs found
Mineralogy of Great Salt Lake: An Analogue for Martian Evaporites
Gypsum (CaSO4 · 2H2O) and mirabilite (Na2SO4 · 10H2O) are common precipitates at the Great Salt Lake (GSL). NASAâs Mars Exploration Rover, Opportunity, found veins of gypsum deposited by water in 2011 and gypsum has been detected on Mars as early as 2005 by the ESAâs Mars Express Orbiter. On Earth, gypsum is formed in hypersaline environments, in minerals left behind when water evaporates, trapping microorganisms in fluid inclusions. Likewise, GSL mirabilite develops when mineral-rich groundwater meets cold winter air to create crystalline structures. While there is no physical evidence of mirabilite on Mars, HiRISE Image data show white mounds that some experts hypothesize are related to saline ground waters. Gypsum obtained from Great Salt Lake was used to develop a method to extract halophilic archaea and culture it in the lab. The method obtained could be used to isolate potential microorganisms present in gypsum samples from Mars. Mirabilite is currently under investigation for its ability to enrich halophilic life
Spin-orbit mode transfer via a classical analog of quantum teleportation
We translate the quantum teleportation protocol into a sequence of coherent
operations involving three degrees of freedom of a classical laser beam. The
protocol, which we demonstrate experimentally, transfers the polarisation state
of the input beam to the transverse mode of the output beam. The role of
quantum entanglement is played by a non-separable mode describing the path and
transverse degrees of freedom. Our protocol illustrates the possibility of new
optical applications based on this intriguing classical analogue of quantum
entanglement.Comment: 5 pages, 7 figure
Desenvolvimento de marcadores microssatélites a partir de bibliotecas genÎmicas enriquecidas para Brachiaria humidicola.
Morphology and biomechanics of the nests of the Common Blackbird Turdus merula
Capsule Common blackbirds select different materials, with varying biomechanical properties, to construct different parts of their nest.
Aims This study tested the hypothesis that outer components of a nest have a more structural role and so are stronger than materials used to line the cup.
Methods Blackbird nests were measured prior to being dismantled to isolate structural components which were tested for mechanical strength and rigidity.
Results Outer nest wall materials were significantly thicker, stronger and more rigid than materials in the inner structural wall or the cup lining. In the vertical plane materials used in the structural wall did not differ. By contrast, lining materials from the bottom of the nest cup were significantly thicker, stronger and more rigid than materials from the top of the cup.
Conclusion Blackbirds use different materials in nest construction roles suited to their properties and so may be able to recognise the structural properties of these materials. Materials on the outside of the nest may have a key structural role during construction
Estimating forest structure in a tropical forest using field measurements, a synthetic model and discrete return lidar data
Tropical forests are huge reservoirs of terrestrial carbon and are experiencing rapid degradation and deforestation. Understanding forest structure proves vital in accurately estimating both forest biomass and also the natural disturbances and remote sensing is an essential method for quantification of forest properties and structure in the tropics. Our objective is to examine canopy vegetation profiles formulated from discrete return LIght Detection And Ranging (lidar) data and examine their usefulness in estimating forest structural parameters measured during a field campaign. We developed a modeling procedure that utilized hypothetical stand characteristics to examine lidar profiles. In essence, this is a simple method to further enhance shape characteristics from the lidar profile. In this paper we report the results comparing field data collected at La Selva, Costa Rica (10° 26âČ N, 83° 59âČ W) and forest structure and parameters calculated from vegetation height profiles and forest structural modeling. We developed multiple regression models for each measured forest biometric property using forward stepwise variable selection that used Bayesian information criteria (BIC) as selection criteria. Among measures of forest structure, ranging from tree lateral density, diameter at breast height, and crown geometry, we found strong relationships with lidar canopy vegetation profile parameters. Metrics developed from lidar that were indicators of height of canopy were not significant in estimating plot biomass (p-value = 0.31, r2 = 0.17), but parameters from our synthetic forest model were found to be significant for estimating many of the forest structural properties, such as mean trunk diameter (p-value = 0.004, r2 = 0.51) and tree density (p-value = 0.002, r2 = 0.43). We were also able to develop a significant model relating lidar profiles to basal area (p-value = 0.003, r2 = 0.43). Use of the full lidar profile provided additional avenues for the prediction of field based forest measure parameters. Our synthetic canopy model provides a novel method for examining lidar metrics by developing a look-up table of profiles that determine profile shape, depth, and height. We suggest that the use of metrics indicating canopy height derived from lidar are limited in understanding biomass in a forest with little variation across the landscape and that there are many parameters that may be gleaned by lidar data that inform on forest biometric properties
On the Levi-Civita solutions with cosmological constant
The main properties of the Levi-Civita solutions with the cosmological
constant are studied. In particular, it is found that some of the solutions
need to be extended beyond certain hypersurfaces in order to have geodesically
complete spacetimes. Some extensions are considered and found to give rise to
black hole structure but with plane symmetry. All the spacetimes that are not
geodesically complete are Petrov type D, while in general the spacetimes are
Petrov type I.Comment: Typed in Revtex, including two figures. To appear in Phys. Rev.
InfluĂȘncia da intermitĂȘncia do tempo de irrigação na cultura da videira festival irrigada por gotejamento, no vale do SubmĂ©dio sĂŁo Francisco.
Portando, esse trabalho teve como objetivo adequar manejos de irrigação que possibilite maiores produçÔes da cultura com a mesma quantidade de ågua requerida
Detecting New Physics from CP-violating phase measurements in B decays
The standard CKM model can be tested and New Physics detected using only
CP-violating phase measurements in B decays. This requires the measurement of a
phase factor which is small in the Standard Model, in addition to the usual
large phases and . We also point out that identifying
violations of the unitarity of the CKM matrix is rather difficult, and cannot
be done with phase measurements alone.Comment: 6 pages, Latex, no figure
Heavy-ion Physics at a Fixed-Target Experiment Using the LHC Proton and Lead Beams (AFTER@LHC): Feasibility Studies for Quarkonium and Drell-Yan Production
We outline the case for heavy-ion-physics studies using the multi-TeV lead
LHC beams in the fixed-target mode. After a brief contextual reminder, we
detail the possible contributions of AFTER@LHC to heavy-ion physics with a
specific emphasis on quarkonia. We then present performance simulations for a
selection of observables. These show that , and
production in heavy-ion collisions can be studied in new energy and
rapidity domains with the LHCb and ALICE detectors. We also discuss the
relevance to analyse the Drell-Yan pair production in asymmetric
nucleus-nucleus collisions to study the factorisation of the nuclear
modification of partonic densities and of further quarkonia to restore their
status of golden probes of the quark-gluon plasma formation.Comment: 18 pages, 7 figure
- âŠ