3,299 research outputs found
The Corralitos Observatory program for the detection of lunar transient phenomena
This is a final report on the establishment, observing procedures, and observational results of a survey program for the detection of lunar transient phenomena (LTP's) by electro-optical image conversion means. For survey, a unique detection system with an image orthicon was used as the primary element in conjunction with a 24-in. f/20 Cassegrainian telescope. Observations in three spectral ranges, with 6,466 man-hours of observing, were actually performed during the period from October 27, 1965, to April 26, 1972. Within this entire period, no color or feature change within the detection capabilities of the instrumentation was observed, either independently or in follow up of amateur LTP reports, with the exception of one general bluing and several localized bluings (probably ascribable to the effects of the terrestrial atmosphere) that were observed solely by the Corralitos system. A table is presented indicating amateur and professional reports of LTP's and the results of efforts to confirm these reports through the Corralitos system
Magnetostriction of a Superconductor: -Results from the Critical-State Model
In many cases, the critical-state theory can be treated as a suffi ciently
accurate approximation for the modelling of the magnetic properties of
superconductors. In the present work, the magnetostrictive hysteresis is
computed for a quite general case of the modified Kim-Anderson model. The
results obtained reproduce many features of the giant magnetostriction
(butterfly-shaped curves) reported in the literature for measurements made on
single-crystal samples of the high-temperature superconductor
. It is shown that addition of a contribution to the
magnetostriction in the superconducting state which is of similar origin as in
the normal state, offers a broader phenomenological interpretation of the
complex magnetostriction hysteresis found in such heavy-fermion compounds as
, or .Comment: 9 LaTeX pages, 4 Postscript figures, WWW version available at
http://is.dal.ca/~zkoziol/super.htm
Social identity and environmental concern: the importance of contextual effects
This study draws on social identity theory to explain differences in individual support for environmental protection, a conative component of environmental concern. It argues that an individual’s identification with higher social units—community, nation, and world—strengthens its in-group solidarity and empathy and, in consequence, its readiness to protect the environment benefitting the in-group’s welfare. The study hypothesizes that country-level manifestations of social identity (1) lift individuals’ support for environmental protection above the level that their own social identity suggests (elevator effect), and (2) reinforce the effect of individuals’ social identity on their support for environmental protection (amplifier effect). Using a sample of over 30,000 individuals located in 38 countries around the world, the study finds strong evidence for the two contextual effects. The findings indicate that social identity plays an important role not just as an individual attribute but also as a central component of culture in fostering environmental concern
Fourier analyses of commensurability oscillations in Fibonacci lateral superlattices
Magnetotransport measurements have been performed on Fibonacci lateral
superlattices (FLSLs) -- two-dimensional electron gases subjected to a weak
potential modulation arranged in the Fibonacci sequence, LSLLSLS..., with
L/S=tau (the golden ratio). Complicated commensurability oscillation (CO) is
observed, which can be accounted for as a superposition of a series of COs each
arising from a sinusoidal modulation representing the characteristic length
scale of one of the self-similar generations in the Fibonacci sequence.
Individual CO components can be separated out from the magnetoresistance trace
by performing a numerical Fourier band-pass filter. From the analysis of the
amplitude of a single-component CO thus extracted, the magnitude of the
corresponding Fourier component in the potential modulation can be evaluated.
By examining all the Fourier contents observed in the magnetoresistance trace,
the profile of the modulated potential seen by the electrons can be
reconstructed with some remaining ambiguity about the interrelation of the
phase between different components.Comment: 11 pages, 10 figures, added references in Introduction, minor
revision
Binding of Host Factors Influences Internalization and Intracellular Trafficking of Streptococcus uberis in Bovine Mammary Epithelial Cells
We showed that internalization of Streptococcus uberis into bovine mammary epithelial cells occurred through receptor- (RME) and caveolae-mediated endocytosis (CME). We reported also that treatment of S. uberis with host proteins including lactoferrin (LF) enhanced its internalization into host cells. Since the underlying mechanism(s) involved in such enhancement was unknown we investigated if preincubation of S. uberis with host proteins drives internalization of this pathogen into host cells through CME. Thus, experiments involving coculture of collagen-, fibronectin-, and LF-pretreated S. uberis with bovine mammary epithelial cells treated with RME and CME inhibitors were conducted. Results showed that internalization of host proteins-pretreated S. uberis into mammary epithelial cells treated with RME inhibitors was higher than that of untreated controls. These results suggest that pretreatment with selected host proteins commits S. uberis to CME, thus avoiding intracellular bactericidal mechanisms and allowing its persistence into bovine mammary epithelial cells
Sugar cane bagasse affects bacterial community dynamics in the sheep rumen.
Ruminants are herbivores and have evolved a symbiotic host-microbe relationship with a complex microbial community inhabiting the rumen allowing the use of lignocellulosic biomass as their main energy source. Considering that diet is one of the main drivers shaping the structure of the rumen microbiome, we investigated the impact of sugarcane bagasse in the rumen bacterial community dynamic using 16S rRNA (V3 and V6 regions) amplicon sequencing. We assessed three rumencannulated adult male sheep (Ovis aries) fed on a diet consisted of 30% concentrate and 70% roughage (control treatment) and three sheep fed on the same diet, but with 14% of the roughage portion replaced by sugarcane bagasse. Fluid and fiber were separately sampled 3 hours and 15, 30, 45, and 60 days after starting the experiment. Total genomic DNA was extracted from 60 independent samples (2 treatments X 3 replicates X 5 time points X 2 types of samples, i.e. fluid or fiber) for downstream analysis. The DNA was used as a template for amplification of V3 and V6 regions of the bacterial 16S rRNA gene and then sequenced using the PGMTM (Ion Torrent). Overall, the two dominant phyla were Bacteroidetes (42%) and Firmicutes (37%). The most abundant bacterial genus was Prevotella (20%), followed by Clostridium (9%), Ruminococcus (8%) and Butyrivibrio (2%). The principal coordinate analysis (PcoA) showed that the bacterial community was significantly different in both treatments at 60 days. Bacteroidales, Actinomycetales and Clostridiales were the top dynamic bacterial orders that significantly increased in relative abundance in the treatment with sugar cane bagasse after 60 days. Canonical correspondence analysis (CCA) revealed that the Clostridiales and Bacteroidales are positively correlated with propionate, butyrate, ammonia, and pH. These results indicate that a small replacement in the diet roughage portion influences de dynamic of specific bacterial taxa. This strategy can be used to reshape the bacterial community in the sheep rumen aiming to enrich the targeted bacterial taxa. Support FAPESP 2012/03848-8, 2012/24588-4 and 2014/00448-4.13th BAGECO1
On the role of a new type of correlated disorder in extended electronic states in the Thue-Morse lattice
A new type of correlated disorder is shown to be responsible for the
appearance of extended electronic states in one-dimensional aperiodic systems
like the Thue-Morse lattice. Our analysis leads to an understanding of the
underlying reason for the extended states in this system, for which only
numerical evidence is available in the literature so far. The present work also
sheds light on the restrictive conditions under which the extended states are
supported by this lattice.Comment: 11 pages, LaTeX V2.09, 1 figure (available on request), to appear in
Physical Review Letter
Growth and Structure of Stochastic Sequences
We introduce a class of stochastic integer sequences. In these sequences,
every element is a sum of two previous elements, at least one of which is
chosen randomly. The interplay between randomness and memory underlying these
sequences leads to a wide variety of behaviors ranging from stretched
exponential to log-normal to algebraic growth. Interestingly, the set of all
possible sequence values has an intricate structure.Comment: 4 pages, 4 figure
Topological Phases in Graphitic Cones
The electronic structure of graphitic cones exhibits distinctive topological
features associated with the apical disclinations. Aharonov-Bohm
magnetoconductance oscillations (period Phi_0) are completely absent in rings
fabricated from cones with a single pentagonal disclination. Close to the apex,
the local density of states changes qualitatively, either developing a cusp
which drops to zero at the Fermi energy, or forming a region of nonzero density
across the Fermi energy, a local metalization of graphene.Comment: 4 pages, RevTeX 4, 3 PostScript figure
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