Effective penetration length and interstitial vortex pinning in superconducting films with regular arrays of defects

In order to compare magnetic and non-magnetic pinning we have nanostructured two superconducting films with regular arrays of pinning centers: Cu (non-magnetic) dots in one case, and Py (magnetic) dots in the other. For low applied magnetic fields, when all the vortices are pinned in the artificial inclusions, magnetic dots prove to be better pinning centers, as has been generally accepted. Unexpectedly, when the magnetic field is increased and interstitial vortices appear, the results are very different: we show how the stray field generated by the magnetic dots can produce an effective reduction of the penetration length. This results in strong consequences in the transport properties, which, depending on the dot separation, can lead to an enhancement or worsening of the transport characteristics. Therefore, the election of the magnetic or non-magnetic character of the pinning sites for an effective reduction of dissipation will depend on the range of the applied magnetic field.Comment: 10 pages, 3 figure

Superconducting/magnetic three state nanodevice for memory and reading applications

We present a simple nanodevice that can operate in two modes: i) three-state memory and ii) reading device. The nanodevice is fabricated with an array of ordered triangular-shaped nanomagnets embedded in a superconducting thin film. The input signal is ac current and the output signal is dc voltage. Vortex ratchet effect in combination with out of plane magnetic anisotropy of the nanomagnets is the background physics which governs the nanodevice performance.Comment: 10 pages, 4 figure

Dynamics of formation and decay of coherence in a polariton condensate

We study the dynamics of formation and decay of a condensate of microcavity polaritons. We investigate the relationship between the number of particles, the emission's linewidth and its degree of linear polarization which serves as the order parameter. Tracking the condensate's formation, we show that, even when interactions are negligible, coherence is not determined only by occupation of the ground state. As a result of the competition between the coherent and thermal fractions of the condensate, the highest coherence is obtained some time after the particle number has reached its maximum

The Cambrian-Ordovician siliciclastic platform of the Balcarce Formation (Tandilia System, Argentina) : Facies, trace fossils, palaeoenvironments and sequence stratigraphy

The Lower Palaeozoic sedimentary cover of the Tandilia (Balcarce Formation) is made up of thick quartz arenite beds together with kaolinitic claystones and thin fine-grained conglomerates. The Balcarce Formation was formed in the nearshore and inner shelf environments of a tide-dominated and storm influenced open platform. It shows many features suggesting tidal sedimentation. Coarse-grained facies were formed by sand bar migration and accretion. Heterolithic packages are interpreted as interbar (swale) deposits. Subordinated HCS sandstones indicate storm events. The recognition of thick progradational clinoforms allows to confirm that the Balcarce sea was open to the south, as suggested years ago through palaeocurrent interpretation. The great abundance and variety of trace fossils is among the most outstanding characteristics of this unit. The ichnotaxa that have been recognised so far are: Ancorichnus ancorichnus, Arthrophycus alleghaniensis, Arthrophycus isp., Bergaueria isp., Cochlichnus isp., Conostichus isp., Cruziana furcifera, Cruziana isp., Daedalus labeckei, Didymaulichnus lyelli, Didymaulichnus isp., Diplichnites isp., Diplocraterion isp., Herradurichnus scagliai, ?Monocraterion isp., Monomorphichnus isp., Palaeophycus alternatus, Palaeophycus tubularis, Palaeophycus isp., Phycodes aff. pedum, Phycodes isp., Plagiogmus isp., Planolites isp., Rusophycus isp., Scolicia isp. and Teichichnus isp. Trace fossils have traditionally been used to assign the Balcarce Formation to the Lower Ordovician, due to the presence of Cruziana furcifera. However, Plagiogmus is typical of Cambrian successions world-wide

High-energy radiation from collisions of high-velocity clouds and the Galactic disc

High-velocity clouds (HVCs) are interstellar clouds of atomic hydrogen that do not follow normal Galactic rotation and have velocities of a several hundred kilometres per second. A considerable number of these clouds are falling down towards the Galactic disc. HVCs form large and massive complexes, so if they collide with the disc a great amount of energy would be released into the interstellar medium. The cloud-disc interaction produces two shocks: one propagates through the cloud and the other through the disc. The properties of these shocks depend mainly on the cloud velocity and the disc-cloud density ratio. In this work, we study the conditions necessary for these shocks to accelerate particles by diffusive shock acceleration and we study the non-thermal radiation that is produced. We analyse particle acceleration in both the cloud and disc shocks. Solving a time-dependent two-dimensional transport equation for both relativistic electrons and protons, we obtain particle distributions and non-thermal spectral energy distributions. In a shocked cloud, significant synchrotron radio emission is produced along with soft gamma rays. In the case of acceleration in the shocked disc, the non-thermal radiation is stronger; the gamma rays, of leptonic origin, might be detectable with current instruments. A large number of protons are injected into the Galactic interstellar medium, and locally exceed the cosmic ray background. We conclude that under adequate conditions the contribution from HVC-disc collisions to the galactic population of relativistic particles and the associated extended non-thermal radiation might be important.Facultad de Ciencias Astronómicas y Geofísica

Biodegradable polyesters reinforced with triclosan loaded polylactide micro/nanofibers: Properties, release and biocompatibility

Mechanical properties and drug release behavior were studied for three biodegradable polyester matrices (polycaprolactone, poly(nonamethylene azelate) and the copolymer derived from 1,9-nonanediol and an equimolar mixture of azelaic and pimelic acids) reinforced with polylactide (PLA) fibers. Electrospinning was used to produce suitable mats constituted by fibers of different diameters (i.e. from micro- to nanoscale) and a homogeneous dispersion of a representative hydrophobic drug (i.e. triclosan). Fabrics were prepared by a molding process, which allowed cold crystallization of PLA micro/nanofibers and hot crystallization of the polyester matrices. The orientation of PLA molecules during electrospinning favored the crystallization process, which was slightly enhanced when the diameter decreased. Incorporation of PLA micro/nanofibers led to a significant increase in the elastic modulus and tensile strength, and in general to a decrease in the strain at break. The brittle fracture was clearer when high molecular weight samples with high plastic deformation were employed. Large differences in the release behavior were detected depending on the loading process, fiber diameter size and hydrophobicity of the polyester matrix. The release of samples with the drug only loaded into the reinforcing fibers was initially fast and then became slow and sustained, resulting in longer lasting antimicrobial activity. Biocompatibility of all samples studied was demonstrated by adhesion and proliferation assays using HEp-2 cell cultures

Osteoartritis luética de rodilla

Se presenta el caso de un varón de 59 años, con antecedente de contacto sexual sospechoso entre 3 y 5 años antes, que desarrolló episodios de derrame articular indoloro en rodilla izquierda con una lesión osteítica destructiva en meseta tibial interna. Tras descartar otras patologías, el diagnóstico se efectuó por la intensa actividad treponéndca demostrada en la serología específica y la buena respuesta al tratamiento antibiótico. Los derrames desaparecieron, persistiendo únicamente la deformidad residual. No conseguimos identificar espiroquetas en el material obtenido por biopsia osteoarticular.We report a 59 years old man with a suspicious sexual contact between 3-5 years ago, who developed repeated painless swelling in his left knee, and a progressive destructive osteitis in his tibia. After rejecting other pathologies, the diagnosis arrived by the high treponemic activity proved by specific serology and the clinical recovery with antibiotic treatment. The swelling disappeared and only the residual deformity persisted. We didn't find any treponema in the biopsy

Regional-scale vegetation heterogeneity in northeastern Patagonia: Environmental and spatial components

Our aim was to describe vegetation heterogeneity at a regional scale in northeastern Patagonia and to identify the environmental variables associated to it. The study area encompasses 13 144 km2 and is characterized by a mixture of species typical of Patagonian steppes and Monte Desert. We performed 48 vegetation relevés, which were randomly assigned to a training set and to a validation set (32 and 16 relevés, respectively). Training set was subjected to cluster analysis, which allowed the identification of two plant communities one related to Patagonian steppes and another to the Monte desert. We derived 3 attributes of the seasonal curve of the NDVI as indicators of ecosystem function: the seasonal amplitude (SA), the date of the maximum (DOM), and the large seasonal integral (LSI). We explored the relationship between NDVI attributes and communities by classification tree analysis. LSI was the strongest predictor among NDVI attributes, separating both communities without misclassification errors. Patagonian steppes occupy areas with higher LSI. The partial RDA analysis explained 38.1% of total data variation, of which 16.5% was ascribed to environment, 7.9% to space, and 13.7% to spatial component of environment. Patagonian steppes are closer to the coast, in areas exhibiting higher annual precipitation and lower annual temperature range than Monte deserts. Our results indicate the occurrence of two plant communities in the study area and highlight the significance of climatic variables to explain their spatial distribution. As most scenarios of future climate predict greater annual thermal amplitude in the study area, the limit between both communities could be displaced eastward

Evidence for BAG3 modulation of HIV-1 gene transcription.

A family of co-chaperone proteins that share the Bcl-2-associated athanogene (BAG) domain are involved in a number of cellular processes, including proliferation and apoptosis. Among these proteins, BAG3 has received increased attention due to its high levels in several disease models and ability to associate with Hsp70 and a number of other molecular partners. BAG3 expression is stimulated during cell response to stressful conditions, such as exposure to high temperature, heavy metals, and certain drugs. Here, we demonstrate that BAG3 expression is elevated upon HIV-1 infection of human lymphocytes and fetal microglial cells. Furthermore, BAG3 protein was detectable in the cytoplasm of reactive astrocytes in HIV-1-associated encephalopathy biopsies, suggesting that induction of BAG3 is part of the host cell response to viral infection. To assess the impact of BAG3 upregulation on HIV-1 gene expression, we performed transcription assays and demonstrated that BAG3 can suppress transcription of the HIV-1 long terminal repeat (LTR) in microglial cells. This activity was mapped to the kappaB motif of the HIV-1 LTR. Results from in vitro and in vivo binding assays revealed that BAG3 suppresses interaction of the p65 subunit of NF-kappaB with the kappaB DNA motif of the LTR. Results from binding and transcriptional assay identified the C-terminus of BAG3 as a potential domain involved in the observed inhibitory effect of BAG3 on p65 activity. These observations reveal a previously unrecognized cell response, that is, an increase in BAG3, elicited by HIV-1 infection, and may provide a new avenue for the suppression of HIV-1 gene expression