8,055 research outputs found
Early-type Galaxies in the Cluster Abell 2390 at z=0.23
To examine the evolution of the early-type galaxy population in the rich
cluster Abell 2390 at z=0.23 we have gained spectroscopic data of 51 elliptical
and lenticular galaxies with MOSCA at the 3.5 m telescope on Calar Alto
Observatory. This investigation spans both a broad range in luminosity
(-19.3>M_B>-22.3) and uses a wide field of view of 10'x10', therefore the
environmental dependence of different formation scenarios can be analysed in
detail as a function of radius from the cluster centre. Here we present results
on the surface brightness modelling of galaxies where morphological and
structural information is available in the F814W filter aboard the Hubble Space
Telescope (HST) and investigate for this subsample the evolution of the
Fundamental Plane.Comment: 5 pages, 5 figures, to appear in "Carnegie Observatories Astrophysics
Series, Vol. 3: Clusters of Galaxies: Probes of Cosmological Structure and
Galaxy Evolution", ed. J. S. Mulchaey, A. Dressler, and A. Oemler (Pasadena:
Carnegie Observatories,
http://www.ociw.edu/ociw/symposia/series/symposium3/proceedings.html
Optimization of -Layer Systems for Josephson Junctions from a Microstructure Point of View
-layer systems are frequently used for Josephson junction-based
superconducting devices. Although much work has been devoted to the
optimization of the superconducting properties of these devices, systematic
studies on influence of deposition conditions combined with structural analyses
on the nanoscale are rare up to now. We have focused on the optimization of the
structural properties of -layer systems deposited on Si(111)
substrates with a particular focus on the thickness homogeneity of the
-tunnel barrier. A standard high-vacuum electron-beam deposition system
was used and the effect of substrate pretreatment, different Al-deposition
temperatures and Al-deposition rates was studied. Transmission electron
microscopy was applied to analyze the structural properties of the
-layer systems to determine the thickness homogeneity of the
layer, grain size distribution in the Al layers, Al-grain boundary
types and the morphology of the interface. We show that the
structural properties of the lower Al layer are decisive for the structural
quality of the whole -layer system. Optimum conditions yield an
epitaxial Al(111) layer on a Si(111) substrate with an Al-layer thickness
variation of only 1.6 nm over more than 10 and large lateral grain
sizes up to 1 . Thickness fluctuations of the -tunnel barrier are
minimized on such an Al layer which is essential for the homogeneity of the
tunnel current. Systematic variation of the Al-deposition rate and deposition
temperature allows to develop an understanding of the growth mechanisms
Optimization conditions of UV-C radiation combined with ultrasound-assisted extraction of cherry tomato (Lycopersicon esculentum) lycopene extract
The aim of this work was to study the effect of UV-C radiation on ultrasound assisted extraction
(UAE) of cherry tomato bioactive compounds. Cherry tomatoes were exposed to two UV-C radiation
doses (0.5 and 1.0 J cm−2
) and stored at 20 ± 0.5 oC for 7 days. Next, they were lyophilized, and
the bioactive compounds were extracted by UAE at 20 KHz. To evaluate the effectiveness of the
extraction process of the bioactive compounds, a CCRD (central composite rotational design) was
used together with RSM (response surface methodology), for extraction times from 4 to 12 minutes
and concentrations (g of lyophilized product / L of ethanol) of 1:10, 1:20 and 1:30. The extracts
obtained from the irradiated tomatoes presented 5.8 times more lycopene content than the controls
and higher antioxidant activity was obtained for 4 and 8 min, in the concentrations 1:10 and 1:20 (m
v−1). Through numerical model optimization, optimal extraction conditions were obtained. The results
demonstrated that by previously irradiating tomatoes with UV-C light, the UAE yielded considerably
higher amounts of lycopene and other bioactives.CNPq (National Council of Technological and Scientific
Development, Brazil), Erasmus Mundus action 2; Fellow
Mundus Project; Department of Chemical Engineering and Food Engineering
(UFSC - Brazil) and the Department of Food Engineering (UAlg - Portugal) .info:eu-repo/semantics/publishedVersio
Trust in the US-EU fruit and vegetable chain: Do US exporters understand EU importers?
Research on organizational and inter organizational trust has become an important field in management and marketing literature, as it is perceived as a pivotal aspect of business transactions. However, clarifications are still needed on the issue of whom we trust; is the person whom we are trading with trusted, or the organization, or just the product‐quality? Not only has this question not been answered within this field of research, neither have cultural differences have been described to any great extent. Additionally, if the perceived factors important to establish trusting relationships may or may not be the same on the buyers and the sellers side in international business transaction in food chains. The primary objective of this research study therefore is to identify how well US exporters understand the elements of trust that establish strong relationships with EU importers. The Analytical Hierarchy Process was used to evaluate the importance of different trust elements in interviews conducted with US exporters and EU importers of fruits and vegetables. Results are compared, providing both a picture of the important facets of trust, as well as whether the partners understand the perspectives of the other partner
Engineering of Chern insulators and circuits of topological edge states
Impurities embedded in electronic systems induce bound states which under
certain circumstances can hybridize and lead to impurity bands. Doping of
insulators with impurities has been identified as a promising route towards
engineering electronic topological states of matter. In this paper we show how
to realize tuneable Chern insulators starting from a three dimensional
topological insulator whose surface is gapped and intentionally doped with
magnetic impurities. The main advantage of the protocol is that it is robust,
and in particular not very sensitive to the impurity configuration. We
explicitly demonstrate this for a square lattice of impurities as well as a
random lattice. In both cases we show that it is possible to change the Chern
number of the system by one through manipulating its topological state. We also
discuss how this can be used to engineer circuits of edge channels.Comment: 9 pages, 6 figure
Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits
This work is concerned with Al/Al-oxide(AlO)/Al-layer systems which are
important for Josephson-junction-based superconducting devices such as quantum
bits. The device performance is limited by noise, which has been to a large
degree assigned to the presence and properties of two-level tunneling systems
in the amorphous AlO tunnel barrier. The study is focused on the
correlation of the fabrication conditions, nanostructural and nanochemical
properties and the occurrence of two-level tunneling systems with particular
emphasis on the AlO-layer. Electron-beam evaporation with two different
processes and sputter deposition were used for structure fabrication, and the
effect of illumination by ultraviolet light during Al-oxide formation is
elucidated. Characterization was performed by analytical transmission electron
microscopy and low-temperature dielectric measurements. We show that the
fabrication conditions have a strong impact on the nanostructural and
nanochemical properties of the layer systems and the properties of two-level
tunneling systems. Based on the understanding of the observed structural
characteristics, routes are derived towards the fabrication of
Al/AlO/Al-layers systems with improved properties.Comment: 28 pages, 4 figure
Detailed Abundances for the Old Population near the Galactic Center: I. Metallicity distribution of the Nuclear Star Cluster
We report the first high spectral resolution study of 17 M giants
kinematically confirmed to lie within a few parsecs of the Galactic Center,
using R=24,000 spectroscopy from Keck/NIRSPEC and a new linelist for the
infrared K band. We consider their luminosities and kinematics, which classify
these stars as members of the older stellar population and the central cluster.
We find a median metallicity of =-0.16 and a large spread from
approximately -0.3 to +0.3 (quartiles). We find that the highest metallicities
are [Fe/H]<+0.6, with most of the stars being at or below the Solar iron
abundance. The abundances and the abundance distribution strongly resembles
that of the Galactic bulge rather than disk or halo; in our small sample we
find no statistical evidence for a dependence of velocity dispersion on
metallicity.Comment: 18 pages, 14 figures, accepted for publication in A
Identification of Anopheles (Nyssorhynchus) marajoara (Diptera: Culicidae) in Bolivia Using Polymerase Chain Reaction and a Restriction Endonuclease
Anopheles (Nyssorhynchus) marajoara Galvão & Damasceno (Diptera: Culicidae) is a member of the Albitarsis cryptic species complex and is a primary vector of human Plasmodium in parts of Brazil. We report the first record of An. marajoara in the department of Cochabamba and confirm its presence in the department of Santa Cruz, Bolivia. We also describe a PCR protocol producing a single amplicon (≈340 bp) of a section of the internal transcribed spacer 2 specific for members of the Albitarsis species complex; the polymerase chain reaction protocol did not amplify the DNA of 17 other species in the subgenus Nyssorhynchus. Digestion of the amplicon with the restriction endonuclease BfaI produces two fragments specific to An. marajoara in Bolivia
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