5,044 research outputs found
Paleomagnetic resu]ts of Jurassic rocks from Siena Harana
Los estudios paleomagnéticos en las Cordilleras Béticas empiezan a ser hoy
en día numerosos. Los trabajos realizados hasta el presente tienen en común el
que todos ellos indican la existencia de rotaciones, algunas de ellas muy importantes en magnitud, y la mayoría en sentido horario. Los vectores paleomagnéticos
determinados han sido utilizados para establecer diferentes modelos
cinemáticos. La mayoría de ellos postulan que las rotaciones observadas son
acomodadas por el movimiento de fallas de salto en dirección o bien, en otros y
no tan numerosos casos, por cabalgamientos.A continuación presentaremos los
resultados de un estudio paleomagnético realizado en dos unidades alóctonas,
una del Subbético Interno y otra de la Dorsal. El objetivo planteado al iniciar esta
investigación fue el detenninar las características paleomagnéticas de los materiales
elegidos y en segundo lugar establecer la existencia o no de rotaciones.
El área escogida es Sierra Jarana, que se encuentra situada a unos 20 km al
NNE de Granada, en el límite entre las zonas Internas y Externas de las Cordilleras
Béticas. En esta sierra se han muestreado dos unidades: la Unidad
de Sierra Harana y la Unidad de Cañamaya. Dichas unidades pertenecen
respectivamente al Dominio Sudibérico (Subbético) y al Dominio de Alborán
(Complejo de la Dorsal). Ambas unidades
están constituidas por materiales mesozoicos y cenozoicos, aunque sus formaciones litoestratigráficas son de distinta naturaleza.Peer reviewe
Searching for signatures of chaos in gamma-ray light curves of selected Fermi-LAT blazars
Blazar variability appears to be stochastic in nature. However, a possibility
of low-dimensional chaos was considered in the past, but with no unambiguous
detection so far. If present, it would constrain the emission mechanism by
suggesting an underlying dynamical system. We rigorously searched for
signatures of chaos in Fermi-Large Area Telescope light curves of 11 blazars.
The data were comprehensively investigated using the methods of nonlinear time
series analysis: phase-space reconstruction, fractal dimension, maximal
Lyapunov exponent (mLE). We tested several possible parameters affecting the
outcomes, in particular the mLE, in order to verify the spuriousness of the
outcomes. We found no signs of chaos in any of the analyzed blazars. Blazar
variability is either truly stochastic in nature, or governed by
high-dimensional chaos that can often resemble randomness.Comment: Pages : 7, figures: 5, accepted in MNRA
Infection levels and species diversity of ascaridoid nematodes in Atlantic cod, Gadus morhua, are correlated with geographic area and fish size
Atlantic cod (Gadus morhua) is among the most important commercial fish species on the world market. Its
infection by ascaridoid nematodes has long been known, Pseudoterranova even being named cod worm. In the
present study, 755 individuals were sampled in the Barents, Baltic and North Seas during 2012–2014.
Prevalences for Anisakis in whole fish and in fillets in the different fishing areas varied from 16 to 100% and
from 12 to 90% respectively. Abundance was also greatly influenced by the sampling area. Generalized additive
model results indicate higher numbers of Anisakis in the North Sea, even after the larger body size was accounted
for. Numbers and prevalence of Anisakis were positively related to fish length or weight. The prevalence of
parasites in whole fish and in fillets was also influenced by the season, with the spring displaying a peak for the
prevalence in whole fish and, at the same time, a drop for the prevalence in fillets. Whereas 46% of cod had
Anisakis larvae in their fillets, the majority (39%) had parasites mainly in the ventral part of the fillet and only
12% had parasites in their dorsal part. This observation is of importance for the processing of the fish. Indeed,
the trimming of the ventral part of the cod fillet would allow the almost total elimination of ascaridoids except
for cod from the Baltic Sea where there was no difference between the dorsal and the ventral part.
The presence of other ascaridoid genera was also noticeable in some areas. For Pseudoterranova, the highest
prevalence (45%) in whole fish was observed in the Northern North Sea, whereas the other areas had prevalences between 3 and 16%. Contracaecum was present in every commercial size cod sampled in the Baltic Sea
with an intensity of up to 96 worms but no Contracaecum was isolated from the Central North Sea. Non-zoonotic
Hysterothylacium was absent from the Baltic Sea but with a prevalence of 83% in the Barents and the Northern
North Sea.
A subsample of worms was identified with genetic-molecular tools and assigned to the species A. simplex (s.s.),
A. pegreffii, P. decipiens (s.s.), P. krabbei, C. osculatum and H. aduncum. In addition to high prevalence and
abundance values, the cod sampled in this study presented a diversity of ascaridoid nematodes with a majority of
fish displaying a co-infection. Out of 295 whole infected fish, 269 were co-infected by at least 2 genera
Role of LGI1 protein in synaptic transmission: From physiology to pathology
Leucine-Rich Glioma Inactivated protein 1 (LGI1) is a secreted neuronal protein highly expressed in the central nervous system and high amount are found in the hippocampus. An alteration of its function has been described in few families of patients with autosomal dominant temporal lobe epilepsy (ADLTE) or with autoimmune limbic encephalitis (LE), both characterized by epileptic seizures. Studies have shown that LGI1 plays an essential role during development, but also in neuronal excitability through an action on voltage-gated potassium Kv1.1 channels, and in synaptic transmission by regulating the surface expression of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPA-R). Over the last decade, a growing number of studies investigating LGI1 functions have been published. They aimed to improve the understanding of LGI1 function in the regulation of neuronal networks using different animal and cellular models. LGI1 appears to be a major actor of synaptic regulation by modulating trans-synaptically pre- and post-synaptic proteins. In this review, we will focus on LGI1 binding partners, “A Disintegrin And Metalloprotease (ADAM) 22 and 23”, the complex they form at the synapse, and will discuss the effects of LGI1 on neuronal excitability and synaptic transmission in physiological and pathological conditions. Finally, we will highlight new insights regarding N-terminal Leucine-Rich Repeat (LRR) domain and C-terminal Epitempin repeat (EPTP) domain and their potentially distinct role in LGI1 function
Effect of quantum interference in the nonlinear conductance of microconstrictions
The influence of the interference of electron waves, which were scattered by
single impurities, on nonlinear quantum conductance of metallic
microconstrictions (as was recently investigated experimentally) is studied
theoretically. The dependence of the interference pattern in the conductance
on the contact diameter and the spatial distribution of impurities is
analyzed. It is shown that the amplitude of conductance oscillation is strongly
depended on the position of impurities inside the constriction.Comment: 6 pages, 4 figures, To appear in PR
Connective neck evolution and conductance steps in hot point contacts
Dynamic evolution of the connective neck in Al and Pb mechanically
controllable break junctions was studied during continuous approach of
electrodes at bias voltages V_b up to a few hundred mV. A high level of power
dissipation (10^-4 - 10^-3 W) and high current density (j > 10^10 A/cm^2) in
the constriction lead to overheating of the contact area, electromigration and
current-enhanced diffusion of atoms out of the "hot spot". At a low electrode
approach rate (10 - 50 pm/s) the transverse dimension of the neck and the
conductance of the junction depend on V_b and remain nearly constant over the
approach distance of 10 - 30 nm. For V_b > 300 mV the connective neck consists
of a few atoms only and the quantum nature of conductance manifests itself in
abrupt steps and reversible jumps between two or more levels. These features
are related to an ever changing number of individual conductance channels due
to the continuous rearrangement in atomic configuration of the neck, the
recurring motion of atoms between metastable states, the formation and breaking
of isolated one-atom contacts and the switching between energetically
preferable neck geometries.Comment: 21 pages 10 figure
Performance of Sulfonated Poly(Vinyl Alcohol)/Graphene Oxide Polyelectrolytes for Direct Methanol Fuel Cells
The use of nanotechnology along with the consideration of a functionalization and stabilization approach to poly(vinyl alcohol) (PVA) is considered useful for the preparation of cost-effective polyelectrolyte membranes. A set of nanocomposite and crosslinked membranes based on PVA/sulfosuccinic acid (SSA)/graphene oxide (GO) are prepared and analyzed as polyelectrolytes in direct methanol fuel cells (DMFCs). The crosslinking and sulfonation by the use of SSA enhances the stability and increase the proton-conducting sites in the PVA structure. The presence of GO augments the stability, remarkably decreases the methanol crossover, and enhances power density curves. An optimum value for proton conductivity is found for the 0.50 wt% of GO proportion, which decreases with higher concentrations of GO. Given the power density curve dependency on both the proton conductivity and the crossover reduction, the performance of these membranes as polyelectrolytes in DMFCs is strictly related to the balance between both factors. Therefore, a proportion of GO of 0.75 wt% may assure suitable proton conductivity of 3 mS cm−1 and high resistance to methanol permeability, reaching promising power density of 16 mW cm−2 with lower hydration levels
Phase-Controlled Force and Magnetization Oscillations in Superconducting Ballistic Nanowires
The emergence of superconductivity-induced phase-controlled forces in the
(0.01-0.1) nN range, and of magnetization oscillations, in nanowire junctions,
is discussed. A giant magnetic response to applied weak magnetic fields, is
predicted in the ballistic Josephson junction formed by a superconducting tip
and a surface, bridged by a normal metal nanowire where Andreev states form.Comment: 5 pages, 3 figure
Efficacy and safety of universal valganciclovir prophylaxis combined with a tacrolimus/mycophenolate-based regimen in kidney transplantation.
BACKGROUND: Immunosuppressive and antiviral prophylactic drugs are needed to prevent acute rejection and infection after transplantation. We assessed the efficacy and safety of the introduction of universal valganciclovir prophylaxis in combination with a tacrolimus/mycophenolate-based regimen in kidney transplantation at our centre. METHODS: We reviewed all consecutive patients who underwent kidney transplantation over a 5.5-year period. Patients transplanted from January 2000 to March 2003 (period 1) were compared to patients from April 2003 to July 2005 (period 2). In period 1 patients were treated with basiliximab, cyclosporine, steroids and mycophenolate (or azathioprine). Prophylaxis with valacyclovir was prescribed in cytomegalovirus (CMV) D+/R- patients, while any R+ patients were managed with a preemptive approach. In period 2, immunosuppression consisted of basiliximab or thymoglobulin induction, tacrolimus, steroids and mycophenolate. Three-month CMV prophylaxis with valganciclovir was used in all at-risk patients. RESULTS: Data analysis included 73 patients (period 1) and 70 (period 2). Acute rejection was more frequent in period 1 than in period 2 (42% vs 7%, p <0.001). Overall, 30% of patients in period 1 were diagnosed with CMV infection/disease requiring antiviral treatment, compared with 11.4% in period 2 (p = 0.003). Late-onset CMV disease remained a problem in D+/R- patients in both periods. There was no difference in incidence of BK virus nephropathy, fungal infections, PTLD, graft loss or mortality. However, 4 cases (5.7%) of delayed transient asymptomatic agranulocytosis were observed in period 2. CONCLUSIONS: The present analysis indicates that the combined regimen introduced in period 2 improved clinical results with a significant decrease in acute rejection and in CMV infection/disease incidence. However, a unique syndrome of delayed transient agranulocytosis probably due to drug myelotoxicity was observed in a subset of patients
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