50,116 research outputs found
Physical parameters and basis transformations in the Two-Higgs-Doublet model
A direct connection between physical parameters of general Two-Higgs-Doublet
Model (2HDM) potentials after electroweak symmetry breaking (EWSB) and the
parameters that define the potentials before EWSB is established. These
physical parameters, such as the mass matrix of the neutral Higgs bosons, have
well defined transformation properties under basis transformations transposed
to the fields after EWSB. The relations are also explicitly written in a basis
covariant form. Violation of these relations may indicate models beyond 2HDMs.
In certain cases the whole potential can be defined in terms of the physical
parameters. The distinction between basis transformations and
reparametrizations is pointed out. Some physical implications are discussed.Comment: 11 pages. 1 figure. v2: references and comments adde
Transition on the entropic elasticity of DNA induced by intercalating molecules
We use optical tweezers to perform stretching experiments on DNA molecules
when interacting with the drugs daunomycin and ethidium bromide, which
intercalate the DNA molecule. These experiments are performed in the low-force
regime from zero up to 2 pN. Our results show that the persistence length of
the DNA-drug complexes increases strongly as the drug concentration increases
up to some critical value. Above this critical value, the persistence length
decreases abruptly and remains practically constant for larger drug
concentrations. The contour length of the molecules increases monotonically and
saturates as drugs concentration increases. Measured in- tercalants critical
concentrations for the persistence length transition coincide with reported
values for the helix-coil transition of DNA-drug complexes, obtained from
sedimentation experiments.Comment: This experimental article shows and discuss a transition observed in
the persistence length of DNA molecules when studied as a function of some
intercalating drug concentrations, like daunomycin and ethidium bromide. It
has 15 pages and 4 figures. The article presented here is in preprint forma
Exchange coupling between magnetic layers across non-magnetic superlattices
The oscillation periods of the interlayer exchange coupling are investigated
when two magnetic layers are separated by a metallic superlattice of two
distinct non-magnetic materials. In spite of the conventional behaviour of the
coupling as a function of the spacer thickness, new periods arise when the
coupling is looked upon as a function of the number of cells of the
superlattice. The new periodicity results from the deformation of the
corresponding Fermi surface, which is explicitly related to a few controllable
parameters, allowing the oscillation periods to be tuned.Comment: 13 pages; 5 figures; To appear in J. Phys.: Cond. Matte
Influence of topographic and hydrographic factors on the spatial distribution of leptospirosis disease in São Paulo county, Brazil: an approach using geospatial techniques and GIS analysis
Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Leptospirosis is a zoonosis caused by Leptospira genus bacteria. Rodents, especially Rattus norvegicus, are the most frequent hosts of this microorganism in the cities. The human transmission occurs by contact with urine, blood or tissues of the rodent and contacting water or mud contaminated by rodent urine. Spatial patterns of concentration of leptospirosis are related to the multiple environmental and socioeconomic factors, like housing near flooding areas, domestic garbage disposal sites and high-density of peoples living in slums located near river channels. We used geospatial techniques and geographical information system (GIS) to analysing spatial relationship between the distribution of leptospirosis cases and distance from rivers, river density in the census sector and terrain slope factors, in Sao Paulo County, Brazil. To test this methodology we used a sample of 183 geocoded leptospirosis cases confirmed in 2007, ASTER GDEM2 data, hydrography and census sectors shapefiles. Our results showed that GIS and geospatial analysis techniques improved the mapping of the disease and permitted identify the spatial pattern of association between location of cases and spatial distribution of the environmental variables analyzed. This study showed also that leptospirosis cases might be more related to the census sectors located on higher river density areas and households situated at shorter distances from rivers. In the other hand, it was not possible to assert that slope terrain contributes significantly to the location of leptospirosis cases.Leptospirosis is a zoonosis caused by Leptospira genus bacteria. Rodents, especially Rattus norvegicus, are the most frequent hosts of this microorganism in the cities. The human transmission occurs by contact with urine, blood or tissues of the rodent an41B8197201CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)sem informaçãoXXIII ISPRS CongressJUL 12-19, 2016Prague, CZECH REPUBLICWe thank to National Council for Scientific and Technological Development of Brazil (CNPq) for funding this researc
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