103 research outputs found
Room temperature spin filtering in epitaxial cobalt-ferrite tunnel barriers
We report direct experimental evidence of room temperature spin filtering in
magnetic tunnel junctions (MTJs) containing CoFe2O4 tunnel barriers via
tunneling magnetoresistance (TMR) measurements.
Pt(111)/CoFe2O4(111)/gamma-Al2O3(111)/Co(0001) fully epitaxial MTJs were grown
in order to obtain a high quality system, capable of functioning at room
temperature. Spin polarized transport measurements reveal significant TMR
values of -18% at 2 K and -3% at 290 K. In addition, the TMR ratio follows a
unique bias voltage dependence that has been theoretically predicted to be the
signature of spin filtering in MTJs containing magnetic barriers. CoFe2O4
tunnel barriers therefore provide a model system to investigate spin filtering
in a wide range of temperatures.Comment: 6 pages, 3 figure
A very low temperature STM for the local spectroscopy of mesoscopic structures
We present the design and operation of a very-low temperature Scanning
Tunneling Microscope (STM) working at in a dilution refrigerator. The
STM features both atomic resolution and micron-sized scanning range at low
temperature. This work is the first experimental realization of a local
spectroscopy of mesoscopic structures at very low temperature. We present
high-resolution current-voltage characteristics of tunnel contacts and the
deduced local density of states of hybrid Superconductor-Normal metal systems.Comment: 5 pages, 5 figures, slightly corrected versio
Population genetic structure of serotine bats (Eptesicus serotinus) across Europe and implications for the potential spread of bat rabies (European bat lyssavirus EBLV-1)
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Understanding of the movements of species at multiple scales is essential to appreciate patterns of population connectivity and in some cases, the potential for pathogen transmission. The serotine bat (Eptesicus serotinus) is a common and widely distributed species in Europe where it frequently harbours European bat lyssavirus type 1 (EBLV-1), a virus causing rabies and transmissible to humans. In the United Kingdom, it is rare, with a distribution restricted to south of the country and so far the virus has never been found there. We investigated the genetic structure and gene flow of E. serotinus across the England and continental Europe. Greater genetic structuring was found in England compared with continental Europe. Nuclear data suggest a single population on the continent, although further work with more intensive sampling is required to confirm this, while mitochondrial sequences indicate an east-west substructure. In contrast, three distinct populations were found in England using microsatellite markers, and mitochondrial diversity was very low. Evidence of nuclear admixture indicated strong male-mediated gene flow among populations. Differences in connectivity could contribute to the high viral prevalence on the continent in contrast with the United Kingdom. Although the English Channel was previously thought to restrict gene flow, our data indicate relatively frequent movement from the continent to England highlighting the potential for movement of EBLV-1 into the United Kingdom.We acknowledge DEFRA and University of Exeter for funding this stud
Mesoscopic proximity effect in double barrier Superconductor/Normal Metal junctions
We report transport measurements down to T=60mK of SININ and SNIN structures
in the diffusive limit. We fabricated Al-AlOx/Cu/AlOx/Cu (SININ) and
Al/Cu/AlOx/Cu (SNIN) vertical junctions. For the first time, a zero bias
anomaly was observed in a metallic SININ structure. We attribute this peak of
conductance to coherent multi-reflections of electrons between the two tunnel
barriers. This conductance maximum is quantitatively fitted by the relevant
theory of mesoscopic SININ structures. When the barrier at the SN interface is
removed (SNIN structure), we observe a peak of conductance at finite voltage
accompagnied by an excess of sub-gap conductance.Comment: 4 pages, 4 figures, editorially approved for publication in Phys.
Rev. B Rapid Com
Long-term survival analysis of masitinib in amyotrophic lateral sclerosis
Background: A randomized, placebo-controlled phase III study (AB10015) previously demonstrated that orally administered masitinib (4.5 mg/kg/day) slowed rate of functional decline, with acceptable safety, in amyotrophic lateral sclerosis (ALS) patients having an ALS Functional Rating Scale-revised (ALSFRS-R) progression rate from disease onset to baseline of <1.1 points/month. Here we assess long-term overall survival (OS) data of all participants from study AB10015 and test whether a signal in OS is evident in an enriched patient population similar to that prospectively defined for confirmatory study AB19001. Methods: Survival status of all patients originally randomized in AB10015 was collected from participating investigational sites. Survival analysis (using the multivariate log-rank test and Cox proportional hazards model, with stratification factors as covariates) was performed on the intention-to-treat population and enriched subgroups, which were defined according to initial randomization, baseline ALSFRS-R progression rate and baseline disease severity. Results: A significant survival benefit of 25 months (p = 0.037) and 47% reduced risk of death (p = 0.025) was observed for patients receiving 4.5 mg/kg/day masitinib (n = 45) versus placebo (n = 62) in an enriched cohort with â©Ÿ2 on each baseline ALSFRS-R individual component score (i.e. prior to any complete loss or severe impairment of functionality) and post-onset ALSFRS-R progression rate <1.1 (i.e. exclusion of very fast progressors) [median OS of 69 versus 44 months, respectively; hazard ratio, 0.53 [95% CI (0.31â0.92)]]. This corresponds to the population enrolled in confirmatory phase III study, AB19001. Conclusions: Analysis of long-term OS (75 months average follow-up from diagnosis) indicates that oral masitinib (4.5 mg/kg/day) could prolong survival by over 2 years as compared with placebo, provided that treatment starts prior to severe impairment of functionality.Fil: Mora, Jesus S.. No especifĂca;Fil: Bradley, Walter G.. University of Miami; Estados UnidosFil: Chaverri, Delia. No especifĂca;Fil: HernĂĄndez Barral, MarĂa. No especifĂca;Fil: Mascias, Javier. No especifĂca;Fil: Gamez, Josep. Universitat AutĂČnoma de Barcelona; EspañaFil: Gargiulo Monachelli, Gisella Mariana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Parque Centenario. CEMIC-CONICET. Centro de Educaciones MĂ©dicas e Investigaciones ClĂnicas "Norberto Quirno". CEMIC-CONICET; ArgentinaFil: Moussy, Alain. No especifĂca;Fil: Mansfield, Colin D.. No especifĂca;Fil: Hermine, Olivier. No especifĂca;Fil: Ludolph, Albert C.. Universitat Ulm; Alemani
Superconducting proximity effect in clean ferromagnetic layers
We investigate superconducting proximity effect in clean ferromagnetic layers
with rough boundaries. The subgap density of states is formed by Andreev bound
states at energies which depend on trajectory length and the ferromagnetic
exchange field. At energies above the gap, the spectrum is governed by resonant
scattering states. The resulting density of states, measurable by tunneling
spectroscopy, exhibits a rich structure, which allows to connect the
theoretical parameters from experiments.Comment: 11 pages, 5 figures (included
Absolute spin-valve effect with superconducting proximity structures
We investigate spin dependent transport in hybrid
superconductor(S)--normal-metal(N)--ferromagnet(F) structures under conditions
of proximity effect. We demonstrate the feasibility of the absolute spin-valve
effect for a certain interval of voltages in a system consisting of two coupled
tri-layer structures. Our results are also valid for non-collinear magnetic
configurations of the ferromagnets.Comment: 1 TEX file, 2 Postscript files. Accepted for publication in Physical
Review Letter
Proximity effects at ferromagnet-superconductor interfaces
We study proximity effects at ferromagnet superconductor interfaces by
self-consistent numerical solution of the Bogoliubov-de Gennes equations for
the continuum, without any approximations. Our procedures allow us to study
systems with long superconducting coherence lengths. We obtain results for the
pair potential, the pair amplitude, and the local density of states. We use
these results to extract the relevant proximity lengths. We find that the
superconducting correlations in the ferromagnet exhibit a damped oscillatory
behavior that is reflected in both the pair amplitude and the local density of
states. The characteristic length scale of these oscillations is approximately
inversely proportional to the exchange field, and is independent of the
superconducting coherence length in the range studied. We find the
superconducting coherence length to be nearly independent of the ferromagnetic
polarization.Comment: 13 Pages total. Compressed .eps figs might display poorly, but will
print fin
Josephson effect in double-barrier superconductor-ferromagnet junctions
We study the Josephson effect in ballistic double-barrier SIFIS planar
junctions, consisting of bulk superconductors (S), a clean metallic ferromagnet
(F), and insulating interfaces (I). We solve the scattering problem based on
the Bogoliubov--de Gennes equations and derive a general expression for the dc
Josephson current, valid for arbitrary interfacial transparency and Fermi wave
vectors mismatch (FWVM). We consider the coherent regime in which quasiparticle
transmission resonances contribute significantly to the Andreev process. The
Josephson current is calculated for various parameters of the junction, and the
influence of both interfacial transparency and FWVM is analyzed. For thin
layers of strong ferromagnet and finite interfacial transparency, we find that
coherent (geometrical) oscillations of the maximum Josephson current are
superimposed on the oscillations related to the crossover between 0 and
states. For the same case we find that the temperature-induced
transition occurs if the junction is very close to the crossovers at zero
temperature.Comment: 13 pages, 6 figure
Mast Cell Diseases in Practice and Research: Issues and Perspectives Raised by Patients and Their Recommendations to the Scientific Community and Beyond
Background: Since 2010, patients and physicians have collaborated to understand unmet needs of patients with mast cell diseases, incorporating mastocytosis and mast cell activation disorders, which include mast cell activation syndromes. Objective: This Open Innovation in Science project aims to expand understanding of the needs of patients affected by mast cell diseases, and encourage global communication among patient advocacy groups, physicians, researchers, industry, and government. A major aim is to support the scientific community's efforts to improve diagnosis, management, therapy, and patientsâ quality of life by addressing unmet needs. Methods: In collaboration with mast cell disease specialists, 13 patient advocacy groups from 12 countries and regions developed lists of top patient needs. A core team of leaders from patient advocacy groups collected and analyzed the data and proposed possible actions to address patient needs. Results: Findings identified similarities and differences among participating countries in unmet needs between patients with mastocytosis and those with mast cell activation syndromes. Issues emphasized struggles relating to the nature and rarity of mast cell diseases, their impact on quality of life, the diagnostic process, access to appropriate care, more effective treatment, and the need for research. Conclusions: Solutions vary across countries because situations differ, in particular regarding the existence of and access to centers of excellence and reference centers. Multifaceted mast cell activation syndrome barriers necessitate innovative approaches to improve access to appropriate care. The outcomes of this project should greatly support scientists and clinicians in their efforts to improve diagnosis, management, and treatment of patients with mastocytosis and mast cell activation disorders.The authors thank Tania Bray, Jan Hempstead, Heather
Mayne, Joanne Mulder-Brambleby, and Irene Wilson for their
supporting contributions, and all patients and families affected
by MCDs, who shared their needs and concerns for development
of this project. Authors involved in study conception and design
were P. Valent, S.V. Jennings, C.C. Finnerty, J.S. Hobart, M.
MartĂn-MartĂnez, K.A. Sinclair, V.M. Slee, J. Agopian, C. Akin,
I. Ălvarez-Twose, P. Bonadonna, A.A. Bowman, K. Brockow, H.
Bumbea, C. de Haro, J.S. Fok, K. Hartmann, N. Hegmann, O.
Hermine, M. Kalisiak, C.H. Katelaris, J. Kurz, P. Marcis, D.
Mayne, D. Mendoza, A. Moussy, G. Mudretzkyj, N. Nidelea
Vaia, M. Niedoszytko, H. Oude Elberink, A. Orfao, D.H.
Radia, S. Rosenmeier, E. Ribada, W. Schinhofen, J. Schwaab, F.
Siebenhaar, M. Triggiani, G. Tripodo, R. Velazquez, Y. Wielink,
F. Wimazal, T. Yigit, and C. Zubrinich. Authors involved in acquisition and review of data were S.V. Jennings, C.C. Finnerty,
J.S. Hobart, M. MartĂn-MartĂnez, K.A. Sinclair, V.M. Slee, J.
Agopian, C. Akin, I. Ălvarez-Twose, P. Bonadonna, A.A.
Bowman, K. Brockow, H. Bumbea, C. de Haro, J.S. Fok, K.
Hartmann, N. Hegmann, O. Hermine, M. Kalisiak, C.H.
Katelaris, J. Kurz, P. Marcis, D. Mayne, D. Mendoza, A.
Moussy, G. Mudretzkyj, N. Nidelea Vaia, M. Niedoszytko, H.
Oude Elberink, A. Orfao, D.H. Radia, S. Rosenmeier, E. Ribada, W. Schinhofen, J. Schwaab, F. Siebenhaar, M. Triggiani, G.
Tripodo, R. Velazquez, Y. Wielink, F. Wimazal, T. Yigit, C.
Zubrinich, and P. Valent. The Core Group (analysis and interpretation of data and drafting of the manuscript) include S.V.
Jennings, C.C. Finnerty, J.S. Hobart, M. MartĂn-MartĂnez, K.A.
Sinclair, and V.M. Slee. Critical revision was performed by S.V.
Jennings, C.C. Finnerty, J.S. Hobart, M. MartĂn-MartĂnez, K.A.
Sinclair, V.M. Slee, J. Agopian, C. Akin, I. Ălvarez-Twose, P.
Bonadonna, A.A. Bowman, K. Brockow, H. Bumbea, C. de
Haro, J.S. Fok, K. Hartmann, N. Hegmann, O. Hermine, M.
Kalisiak, C.H. Katelaris, J. Kurz, P. Marcis, D. Mayne, D.
Mendoza, A. Moussy, G. Mudretzkyj, N. Nidelea Vaia, M.
Niedoszytko, H. Oude Elberink, A. Orfao, D.H. Radia, S.
Rosenmeier, E. Ribada, W. Schinhofen, J. Schwaab, F. Siebenhaar, M. Triggiani, G. Tripodo, R. Velazquez, Y. Wielink, F Wimazal, T. Yigit, C. Zubrinich, and P. Valent
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