580 research outputs found
Active dispersal of Aedes albopictus: a mark-release-recapture study using self-marking units
BACKGROUND: Understanding the dispersal dynamics of invasive mosquito species is fundamental to improve vector surveillance and to target control efforts. Aedes albopictus has been deemed a poor flyer as its range of active dispersal is generally assumed to be limited to a few hundred metres, while laboratory studies suggest this mosquito could actually fly several kilometres. The discrepancy may be due to differences in the local environment or to the methodological approach. In Switzerland, Ae. albopictus has been present since 2003 and has since then expanded its range. While passive dispersal is a key driver, it remains unclear how far this mosquito spreads through active flight and what the age structure and size of the local population are, all important parameters for vector surveillance and control. METHOD: We investigated the active dispersal, daily survival rate and population size of Ae. albopictus in mark-release-recapture studies in Coldrerio and Lugano, two areas of intensive control in Switzerland. To mark mosquitoes emerging from breeding sites, we used self-marking units with fluorescent pigment that have minimal impact on mosquito survival and behaviour. We recaptured the adult mosquitoes with BG-Sentinel traps within a radius of 1 km from the marking units over 22 consecutive days. RESULTS: We found that 77.5% of the recaptured Ae. albopictus individuals flew further than 250 m, the limit that is usually deemed sufficient for vector containment. The average age of females and males was 8.6 days and 7.8 days in Coldrerio and Lugano, respectively, while the estimated mosquito population densities were 134 mosquitoes/ha in Coldrerio and 767 mosquitoes/ha in Lugano. CONCLUSIONS: Self-marking units are an effective tool to mark wild mosquitoes. Using this approach, we found that mosquitoes survive long enough to potentially transmit arboviral disease in our study area and that host-seeking Ae. albopictus females may travel further than previously assumed for European mosquito populations. This finding has direct implications for vector control as emergency treatments around positive cases, as well as surveillance and control around detections of new infestations, might need to be extended beyond the usual recommended range of just a few hundred metres
Validation of Constraints Among Configuration Parameters Using Search-Based Combinatorial Interaction Testing
The appeal of highly-configurable software systems lies in their adaptability to users’ needs. Search-based Combinatorial Interaction Testing (CIT) techniques have been specifically developed to drive the systematic testing of such highly-configurable systems. In order to apply these, it is paramount to devise a model of parameter configurations which conforms to the software implementation. This is a non-trivial task. Therefore, we extend traditional search-based CIT by devising 4 new testing policies able to check if the model correctly identifies constraints among the various software parameters. Our experiments show that one of our new policies is able to detect faults both in the model and the software implementation that are missed by the standard approaches
Self organized mode locking effect in superconductor / ferromagnet hybrids
The vortex dynamics in a low temperature superconductor deposited on top of a
rectangular array of micrometer size permalloy triangles is investigated
experimentally. The rectangular unit cell is such that neighboring triangles
physically touch each other along one direction. This design stabilizes
remanent states which differ from the magnetic vortex state typical of
individual non-interacting triangles. Magnetic Force Microscopy images have
revealed that the magnetic landscape of the template can be switched to an
ordered configuration after magnetizing the sample with an in-plane field. The
ordered phase exhibits a broad flux flow regime with relatively low critical
current and a highly anisotropic response. This behavior is caused by the
spontaneous formation of two separated rows of vortices and antivortices along
each line of connected triangles. The existence of a clear flux flow regime
even for zero external field supports this interpretation. The density of
induced vortex-antivortex pairs is directly obtained using a high frequency
measurement technique which allows us to resolve the discrete motion of
vortices. Strikingly, the presence of vortex-antivortex rows gives rise to a
self organized synchronized motion of vortices which manifests itself as field
independent Shapiro steps in the current-voltage characteristics.Comment: 9 pages, 11 figure
Domain wall displacement in Py square ring for single nanometric magnetic bead detection
A new approach based on the domain wall displacement in confined
ferromagnetic nanostructures for attracting and sensing a single nanometric
magnetic particles is presented. We modeled and experimentally demonstrated the
viability of the approach using an anisotropic magnetoresistance device made by
a micron-size square ring of Permalloy designed for application in magnetic
storage. This detection concept can be suitable to biomolecular recognition,
and in particular to single molecule detection.Comment: 8pages, 3figure
Bioetica «laica» e bioetica «cattolica» Teologia morale e questioni bioetiche
En la sociedad contemporánea la discusión
sobre cuestiones bioéticas constituye uno de los
principales ámbitos de confrontación polÃtica y social.
En este contexto, en paÃses como España e Italia se
observa la existencia de dos tendencias enfrentadas
entre sÃ. Por un lado, una perspectiva religiosamente
inspirada (bioética «católica») y por otro, aquella que
se define a si misma como «laica», cuyos partidarios
sostienen que la exigencia de racionalidad que debe
caracterizar a la bioética es incompatible con la presencia
de valores religiosos y teológicos. En este trabajo
se analizan estas dos perspectivas bioéticas, haciendo
hincapié en dos documentos paradigmáticos
de la bioética «laica», el «Manifesto di bioetica laica»
y el «Nuovo manifesto di bioetica laica», publicados en
Italia entre el final del siglo pasado y principios de este
siglo. El trabajo de investigación está estructurado de
la siguiente manera: comienza por el análisis de la
perspectiva bioética «laica», para adentrarse posteriormente
en el estudio de la fundamentación antropológica
que la reflexión puramente racional ofrece
como marco para una evaluación adecuada de las
cuestiones bioéticas. Luego se analiza la contribución
de la Revelación y de la reflexión teológico-moral,
tanto en el lado antropológico que en el de la fundamentación
del juicio ético. ------------------ In modern-day society the debate regarding
bioethical questions constitutes one of the principle
areas of political and social confrontation. Within this
context, in countries like Spain and Italy, one can observe
the existence of two tendencies that confront
each other. On one hand there is the religious perspective
founded upon Religious Faith («Catholic»
Bioethics) and on the other hand that which defines
itself as «secular», the partisans of which affirm that
the rationality which must characterise Bioethics is
incompatible with religious and theological values. In
the present research, we analyse the above two perceptions
of Bioethics, making due reference two paradigmatic
documents of the «secular» Bioethics –the
«Manifesto di bioetica laica» and the «Nuovo manifesto
di bioetica laica»– both published in Italy at the end of
the 20th century and the beginning of the 21st. This
investigation is structured in the following manner:
the first part is an analysis of the «secular» bioethical
standpoint. This paves way for the study of the anthropological
foundation that the purely rational reflection
offers as a measure of the evaluation of bioethical
enquiries. The second part of the investigation is
dedicated to the analysis of the contribution of Divine
Revelation and the Theological-moral deliberation
and this not only of the anthropological aspect but
also in the establishment of the ethical judgement
Intensity of Brillouin light scattering from spin waves in magnetic multilayers with noncollinear spin configurations: Theory and experiment
The scattering of photons from spin waves (Brillouin light scattering -- BLS)
is a well-established technique for the study of layered magnetic systems. The
information about the magnetic state and properties of the sample is contained
in the frequency position, width, and intensity of the BLS peaks. Previously
[Phys. Rev. B 67, 184404 (2003)], we have shown that spin wave frequencies can
be conveniently calculated within the ultrathin film approach, treating the
intralayer exchange as an effective bilinear interlayer coupling between thin
virtual sheets of the ferromagnetic layers. Here we give the consequent
extension of this approach to the calculation of the Brillouin light scattering
(BLS) peak intensities. Given the very close relation of the BLS cross-section
to the magneto-optic Kerr effect (MOKE), the depth-resolved longitudinal and
polar MOKE coefficients calculated numerically via the usual magneto-optic
formalism can be employed in combination with the spin wave precessional
amplitudes to calculate full BLS spectra for a given magnetic system. This
approach allows an easy calculation of BLS intensities even for noncollinear
spin configurations including the exchange modes. The formalism is applied to a
Fe/Cr/Fe/Ag/Fe trilayer system with one antiferromagnetically coupling spacer
(Cr). Good agreement with the experimental spectra is found for a wide variety
of spin configurations.Comment: 19 pages, 5 figure
Absence of stable collinear configurations in Ni(001)ultrathin films: canted domain structure as ground state
Brillouin light scattering (BLS) measurements were performed for (17-120)
Angstrom thick Cu/Ni/Cu/Si(001) films. A monotonic dependence of the frequency
of the uniform mode on an in-plane magnetic field H was observed both on
increasing and on decreasing H in the range (2-14) kOe, suggesting the absence
of a metastable collinear perpendicular ground state. Further investigation by
magneto-optical vector magnetometry (MOKE-VM) in an unconventional canted-field
geometry provided evidence for a domain structure where the magnetization is
canted with respect to the perpendicular to the film. Spin wave calculations
confirm the absence of stable collinear configurations.Comment: 6 pages, 3 figures (text, appendix and 1 figure added
C60/NiFe combination as a promising platform for molecular spintronics
Spintronics based on ferromagnetic metals and organic semiconductors has attracted great interest in recent years. Molecular-based spintronic devices, such as magnetic tunnel junctions, have been demonstrated with performances competing with those of conventional inorganic devices. Still, there is huge margin for improvement, as many details about the injection of spin-polarized electrons into the molecular layer remain not completely understood. In order to achieve better understanding and control of the physical mechanisms, it is necessary to explore various combinations of ferromagnetic metals and organic semiconductors. In this letter, we study the properties of the combination between the ferromagnetic metal NiFe (commonly known as Permalloy or Py) and the molecular system C60. We produced C60/Py bilayers and characterized them structurally, electrically and magnetically. The C 60 films grow smoothly on both Py and SiO2 substrates, and we estimate that a 5-nm-thick C60 film covers completely the surface underneath without leaving pinholes and can be therefore used in a vertical device, as confirmed by electrical characterization. Furthermore, the C 60 film is robust against the deposition of the top metal electrode, being the intermixing layer of only 1-2 nm at the C60/Py interface. Finally, we show that the magnetic properties of Py are not affected by the deposition sequence, and that a 5-nm-thick Py layer on top of a C60 layer keeps its magnetic properties intact. These results show that the combination between Py and C60 provides a robust template platform for the development of molecular spintronics, and can be used later on for more sophisticated investigations, such as the role of the interfaces in the spin injection.Fil: Gobbi, M.. No especifÃca;Fil: Pascual, A.. No especifÃca;Fil: Golmar, Federico. Instituto Nacional de TecnologÃa Industrial; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Llopis, R.. No especifÃca;Fil: Vavassori, P.. No especifÃca;Fil: Casanova, F.. No especifÃca;Fil: Hueso, L. E.. No especifÃca
On topological spin excitations on a rigid torus
We study Heisenberg model of classical spins lying on the toroidal support,
whose internal and external radii are and , respectively. The isotropic
regime is characterized by a fractional soliton solution. Whenever the torus
size is very large, , its charge equals unity and the soliton
effectively lies on an infinite cylinder. However, for R=0 the spherical
geometry is recovered and we obtain that configuration and energy of a soliton
lying on a sphere. Vortex-like configurations are also supported: in a ring
torus () such excitations present no core where energy could blow up. At
the limit we are effectively describing it on an infinite
cylinder, where the spins appear to be practically parallel to each other,
yielding no net energy. On the other hand, in a horn torus () a singular
core takes place, while for (spindle torus) two such singularities
appear. If is further diminished until vanish we recover vortex
configuration on a sphere.Comment: 11 pages, 9 figure
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