1,331 research outputs found
Calculation of electrostatic fields using quasi-Green's functions: application to the hybrid Penning trap.
Penning traps offer unique possibilities for storing, manipulating and investigating charged particles with high sensitivity and accuracy. The widespread applications of Penning traps in physics and chemistry comprise e.g. mass spectrometry, laser spectroscopy, measurements of electronic and nuclear magnetic moments, chemical sample analysis and reaction studies. We have developed a method, based on the Green's function approach, which allows for the analytical calculation of the electrostatic properties of a Penning trap with arbitrary electrodes. The ansatz features an extension of Dirichlet's problem to nontrivial geometries and leads to an analytical solution of the Laplace equation. As an example we discuss the toroidal hybrid Penning trap designed for our planned measurements of the magnetic moment of the (anti)proton. As in the case of cylindrical Penning traps, it is possible to optimize the properties of the electric trapping fields, which is mandatory for high-precision experiments with single charged particles. Of particular interest are the anharmonicity compensation, orthogonality and optimum adjustment of frequency shifts by the continuous SternGerlach effect in a quantum jump spectrometer. The mathematical formalism developed goes beyond the mere design of novel Penning traps and has potential applications in other fields of physics and engineering
Prácticas de Óptica Visual I. Miopía, parte 1 (curso 2011-2012)
Guión de prácticas 3 de laboratorio: miopía, parte 1
"Digitaria sanguinalis - Ustilago syntherismae" pathosystem: changes in the reproductive development of plants due to fungal infection
El objetivo del estudio fue conocer cómo la infección por carbón causado por “Ustilago syntherismae” afecta al número de ápices reproductivos (NAR) que forman las plantas de garranchuelo (Digitaria sanguinalis) en una generación. Se marcaron 24 cuadrados de 0,25m2, se escardaron manualmente para dejar únicamente plantas de garranchuelo, y se registraron la densidad y NAR de cada planta. El NAR se sometió a un análisis de la covarianza que contempló el efecto principal tipo de individuo (con carbón o sin carbón), la densidad, y su interacción. El tipo de ápice reproductivo y la interacción fueron muy significativos en el rango de densidades registrado (de 12 a 156 pl m-2). A densidades elevadas, la media del NAR de las plantas con carbón casi dobló la de las plantas aparentemente sanas, es decir las plantas enfermas desarrollaron más soros que inforescencias se hubieran formado en plantas sanas.The main objective of our study was to evaluate how the infection by “Ustilago syntherismae” (loose smut) can affect the number of apical reproductive buds (NAR) formed in Digitaria sanguinalis plants during one generation. The study was performed using 24 quadrats of 0.25m2 in which seedlings of other species were removed. The large crabgrass densities and the NAR of each plant were obtained. The NAR was subjected to an analysis of covariance considering the type of plant (smutted or non-smutted) as a principal effect, the plant density, and their interaction. The type of reproductive bud and the interaction were highly significant sources of variance at the observed densities (ranging from 12 to 156 pl m-2). At high plant densities, NAR of smutted plants was, on average, near to the double of that non-smutted plants. The number of sori registered in smutted plants was much higher than the expected number of inflorescences if they would not have been infected
Clustering of LMS Use Strategies with Autoencoders
Learning Management Systems provide teachers with many functionalities to offer materials to students, interact with them and manage their courses. Recognizing teachers’ instructing styles from their course designs would allow recommendations and best practices to be made. We propose a method that determines teaching style in an unsupervised way from the course structure and use patterns. We define a course classification approach based on deep learning and clustering. We first use an autoencoder to reduce the dimensionality of the input data, while extracting the most important characteristics; thus, we obtain a latent representation of the courses. We then apply clustering techniques to the latent data to group courses based on their use patterns. The results show that this technique improves the clustering performance while avoiding the manual data pre-processing work. Furthermore, the obtained model defines seven course typologies that are clearly related to different use patterns of Learning Management Systems
New Moiré Landscapes for Atomic Spins
The interactions of the spins of single atoms with a substrate can be controlled via the moiré lattice created by depositing a 2D material on top of the substrate
Follicular adenomatoid odontogenic tumor : immunohistochemical study
Adenomatoid odontogenic tumor (AOT) is an uncommon benign odontogenic lesion that affects young patients, with female predominance, mainly in second decade, showing a radiolucent unilocular image associated with an unerupted tooth, usually a canine. In spite of previous and confusing denominations, such as adenoameloblastoma or adenomatoid ameloblastic tumor, AOT is a benign tumor with a very low rate of recurrence, that show a peculiar morphological picture (basaloid appearance with glandular-like structures, calcifying areas, and amiloid-like material) that allow its histopathological recognition. We present a clinicopathological analysis of a case of follicular AOT affecting the mandible in a 9 years-old female patient associated with unerupted lower left canine. Immunohistochemical study showed some data previously unrecognised. All cellular types that composed AOT showed nuclear positivity for p63 indicating a basal characterization in the different cellular components. According to its benign character and low potential for recurrence, AOT revealed a scant proliferative activity (2-3% nuclei showed Ki-67 positivity) limited to some epithelial nodules (AE1-3 +) of fusiform appearance. Absence of reactivity for hormonal receptors (RE and RPg) excluded a possible hormonodependence in AOT that could explain the observed female predominance
High-power test results of a 3 GHz single-cell cavity
Compact, reliable and little consuming accelerators are required for the
treatment of tumours with ions. TERA proposes the "cyclinac", composed of a
high-frequency, fast-cycling linac which boosts the energy of the particles
previously accelerated in a cyclotron. The dimensions of the linac can be
reduced if high gradients are used. TERA initiated a high-gradient test program
to understand the operational limit of such structures. The program foresees
the design, prototyping and high-power test of several high-gradient structures
operating at 3 and 5.7 GHz. The high-power tests of the 3 GHz single-cell
cavity were completed in Winter 2012. The maximum BDR threshold measured for
Emax of 170 MV/m and RF pulses of 2.5 \mu s was 3 x 10-6 bpp/m
Simulation studies on natural circulation phenomena during an SBO accident
[EN] Natural circulation flow capability for removing decay core power has been demonstrated, and several studies have focused on taking advantage of this fact. This work studies the sequence of events that occur during a station blackout accident, in which natural circulation is the dominant flow pattern in the primary system. To this end, the Test A1.1 carried out in ATLAS facility is analyzed and a TRACE5 model is developed paying special attention on the modeling of heat losses. This phenomenon is very influential in the flow capacity and this is demonstrated through the correlation G~(Q-qloss )m between the net power Q-qloss and the mass flow G, that has been established from simulations under steady-state conditions. The Test A1.1 reproduction shows the TRACE5 code adequacy to investigate natural circulation phenomena, which are difficult to control in a facility. In addition, the heat loss modeling technique using constant heat transfer coefficients is substantiated.The authors are grateful to the Management Board of the OECD-ATLAS Project for their consent to this publication, and thank the Spanish Nuclear Regulatory Body (CSN) for the technical and financial support under the agreement STN/4524/2015/640 and the Spanish Ministerio de Economia, Industria y Competitividad under the agreement ENE2017-89029-P. They also thank Ronald Harrington, from USNRC, for sharing the preliminary TRACE model used in this work.Lorduy, M.; Gallardo Bermell, S.; Verdú Martín, GJ. (2018). Simulation studies on natural circulation phenomena during an SBO accident. Applied Thermal Engineering. 139:514-523. https://doi.org/10.1016/j.applthermaleng.2018.04.130S51452313
Spectral responsivity vs. action spectrum in digital photography
We propose an experimental and theoretical methodology
based on spectroradiometric procedures to determine the
spectral sensitivity of digital still cameras (DSC). The
opto-electronic conversion spectral functions (OECSF's)
are obtained from normalized digital level (NDL) vs.
spectral exposure data, fitted by a typical sigmoidal
transition curve. At this stage, we define spectral
responsivity r(λ, H) and action spectrum a(λ, NDL), which
are conceptual derivations of the general concept of
spectral sensitivity of any image sensor. Then, the real
spectral responsivity and action spectrum are represented
as 3-dimensional functions, where r(λ, H = constant) and
a(λ, NDL = constant) profiles are scaled relatively to
determine the valid linear output range of the digital
image capture device. This range would serve to design
the colorimetric profile of the camera with CIE-1931 XYZ
standard observer, which is considered as a linear color
image sensor.This research was supported by the Comisión
Interministerial de Ciencia y Tecnología (CICYT) (Spain)
under grants TAP96-0887 and TAP99-0856
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