5,425 research outputs found
Total electron scattering cross sections from thiophene for the (1-300 eV) impact energy range
Experimental electron scattering cross sections for thiophene in the impact energy range from 1 to 300 eV have been measured with a magnetically confined electron transmission-beam apparatus. Random uncertainty limits have been estimated to be less than 5%, and systematic errors derived from acceptance angle limitations have also been identified and evaluated. Experimental values are compared with our previous low energy (1-15 eV) R-matrix and intermediate/high energy (15-300 eV) IAM-SCAR+I calculations finding reasonable agreement, within the combined uncertainty limits. Some of the low energy shape and core-excited resonances predicted by previous calculations are experimentally confirmed in this study
Rashba coupling in quantum dots: exact solution
We present an analytic solution to the problem of the Rashba spin-orbit
coupling in semiconductor quantum dots. We calculate the exact energy spectrum,
wave-functions, and spin--flip relaxation times. We discuss various effects
inaccessible via perturbation theory. In particular, we find that the effective
gyromagnetic ratio is strongly suppressed by the spin-orbit coupling. The
spin-flip relaxation rate has a maximum as a function of the spin-orbit
coupling and is therefore suppressed in both the weak- and strong coupling
limits.Comment: 5 pages, 4 figs, reference adde
Full-field swept-source optical coherence tomography and neural tissue classification for deep brain imaging
Optical coherence tomography can differentiate brain regions with intrinsic contrast and at a micron scale resolution. Such a device can be particularly useful as a realtime neurosurgical guidance tool. We present, to our knowledge, the first full-field swept-source optical coherence tomography system operating near a wavelength of 1310 nm. The proof-of-concept system was integrated with an endoscopic probe tip, that is compatible with deep brain stimulation keyhole neurosurgery. Neuroimaging experiments were performed on ex vivo brain tissues and in vivo in rat brains. Using classification algorithms involving texture features and optical attenuation, images were successfully classified into three brain tissue types
First investigation of a novel 2D position-sensitive semiconductor detector concept
This paper presents a first study of the performance of a novel 2D
position-sensitive microstrip detector, where the resistive charge division
method was implemented by replacing the metallic electrodes with resistive
electrodes made of polycrystalline silicon. A characterization of two
proof-of-concept prototypes with different values of the electrode resistivity
was carried out using a pulsed Near Infra-Red laser. The experimental data were
compared with the electrical simulation of the sensor equivalent circuit
coupled to simple electronics readout circuits. The good agreement between
experimental and simulation results establishes the soundness of resistive
charge division method in silicon microstrip sensors and validates the
developed simulation as a tool for the optimization of future sensor
prototypes. Spatial resolution in the strip length direction depends on the
ionizing event position. The average value obtained from the protype analysis
is close to 1.2% of the strip length for a 6 MIP signal.Comment: 14 pages, 12 figure
Functional and molecular characterization of inherited platelet disorders in the Iberian Peninsula: results from a collaborative study
BACKGROUND:
The diagnostic evaluation of inherited platelet disorders (IPDs) is complicated and time-consuming, resulting in a relevant number of undiagnosed and incorrectly classified patients. In order to evaluate the spectrum of IPDs in individuals with clinical suspicion of these disorders, and to provide a diagnostic tool to centers not having access to specific platelets studies, we established the project "Functional and Molecular Characterization of Patients with Inherited Platelet Disorders" under the scientific sponsorship of the Spanish Society of Thrombosis and Haemostasis.
PATIENTS/METHODS:
Subjects were patients from a prospective cohort of individuals referred for clinical suspicion of IPDs as well as healthy controls. Functional studies included light transmission aggregation, flow cytometry, and when indicated, Western-blot analysis of platelet glycoproteins, and clot retraction analysis. Genetic analysis was mainly performed by sequencing of coding regions and proximal regulatory regions of the genes of interest.
RESULTS:
Of the 70 cases referred for study, we functionally and molecularly characterized 12 patients with Glanzmann Thrombasthenia, 8 patients with Bernard Soulier syndrome, and 8 with other forms of IPDs. Twelve novel mutations were identified among these patients. The systematic study of patients revealed that almost one-third of patients had been previously misdiagnosed.
CONCLUSIONS:
Our study provides a global picture of the current limitations and access to the diagnosis of IPDs, identifies and confirms new genetic variants that cause these disorders, and emphasizes the need of creating reference centers that can help health care providers in the recognition of these defects
Degradación física de los suelos del sector comprendido entre la Sierra de las Guájara y el río Albuñuelas
The authors have carried out an study on potential physical degradation phenomena of tipical soils belonging to the sector between Sierra of Guájaras and the Albuñuelas river. Provisonal methodology for soil degradation evaluation F.A.O. (1980) was used, expressing the results as a porcentage of permeability reduction.Se realiza un estudio de los fenónemos de degradación física potencial que pueden sufrir los suelos modales del sector comprendido entre la Sierra de las Guájaras y el río Albuñuelas. Se emplea la Metodología provisional para la evaluación de la degradación de suelos de la F.A.O. (1980), expresando los resultados obtenidos en tanto por ciento de reducción de la permeabilidad
Degradación física de los suelos del sector comprendido entre la Sierra de las Guájara y el río Albuñuelas
Se realiza un estudio de los fenónemos de degradación física potencial
que pueden sufrir los suelos modales del sector comprendido entre la Sierra de
las Guájaras y el río Albuñuelas.
Se emplea la Metodología provisional para la evaluación de la degradación de suelos de la F.A.O. (1980), expresando los resultados obtenidos en
tanto por ciento de reducción de la permeabilidad.The authors have carried out an study on potential physical degradation
phenomena of tipical soils belonging to the sector between Sierra of Guájaras
and the Albuñuelas river.
Provisonal methodology for soil degradation evaluation F.A.O. (1980)
was used, expressing the results as a porcentage of permeability reduction
Non-perturbative effects in semi-leptonic B_c decays
We discuss the impact of the soft degrees of freedom inside the B_c meson on
its rate in the semi-leptonic decay B_c -> X l nu_l where X denotes light
hadrons below the D^0 threshold. In particular we identify contributions
involving soft hadrons which are non-vanishing in the limit of massless
leptons. These contributions become relevant for a measurement of the purely
leptonic B_c decay rate, which due to helicity suppression involves a factor
m_l^2 and thus is much smaller than the contributions involving soft hadrons.Comment: LaTeX, 22 pages, 1 figur
Authentication of tequilas using pattern recognition and supervised classification
[Abstract] Sales of reputed, Mexican tequila grown substantially in last years and, therefore, counterfeiting is increasing steadily. Hence, methodologies intended to characterize and authenticate commercial beverages are a real need. They require a combination of analytical characterization and chemometric tools. This work reports concisely on the former and focus on the chemometric tools employed so far in connection with them. Further, a practical case study presents the classification capabilities of nine supervised classification methods to differentiate white, rested, aged and extra-aged tequilas. The largest set of certified tequilas employed so far was considered. In general, non linear methods performed best than linear ones (accuracy higher than 94% in both training and validation). The case study demonstrates that it is possible to develop fast, cheap, easy to implement and reliable analytical methodologies to authenticate and classify samples of tequilas.Xunta de Galicia; GRC2013-047Ministerio de Industria, Energía y Competitividad; FJCI-2015-2607
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