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

Reflexiones y medidas sobre el consumo de bebidas alcohólicas

El consumo de alcohol está establecido culturalmente, arraigado en nuestras conductas o hábitos diarios de bebida y por ello, influyendo directamente en la salud de los ciudadanos de nuestro país y en concreto, determinando la salud de nuestros jóvenes. La situación del alcohol respecto a la prevención es difícil, con programas genéricos, sin la participación de las madres y padres, con el consumo de bebidas alcohólicas establecido en muchos hogares, con la tiranía de la publicidad y la falta de programa claro de actuación desde las distintas administraciones; la solución, desafortunadamente, está muy alejada de nuestra realidad a corto plazo. Se apuntan algunas reflexiones sobre la necesidad de proteger a los menores, de prevenir e intervenir, en general, sobre el consumo de las bebidas alcohólicas. Se describen los mecanismos por los que las bebidas alcohólicas se trasmiten de generación en generación en nuestra sociedad. Y finalmente se plantea promover estrategias sobre el manejo del estado anímico dirigidas sobre todo a los jóvenes

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

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

Strong magnetic coupling of an ultracold gas to a superconducting waveguide cavity

Placing an ensemble of $10^6$ ultracold atoms in the near field of a superconducting coplanar waveguide resonator (CPWR) with $Q \sim 10^6$ one can achieve strong coupling between a single microwave photon in the CPWR and a collective hyperfine qubit state in the ensemble with $g_\textit{eff} / {2 \pi} \sim 40$ kHz larger than the cavity line width of ${\kappa}/{2 \pi} \sim 7$ kHz. Integrated on an atomchip such a system constitutes a hybrid quantum device, which also can be used to interconnect solid-state and atomic qubits, to study and control atomic motion via the microwave field, observe microwave super-radiance, build an integrated micro maser or even cool the resonator field via the atoms

Soil shapes community structure through fire

7 páginas, 2 figuras, 2 tablas.Recurrent wildWres constitute a major selecting force in shaping the structure of plant communities. At the regional scale, Wre favours phenotypic and phylogenetic clustering in Mediterranean woody plant communities. Nevertheless, the incidence of Wre within a Wre-prone region may present strong variations at the local, landscape scale. This study tests the prediction that woody communities on acid, nutrient-poor soils should exhibit more pronounced phenotypic and phylogenetic clustering patterns than woody communities on fertile soils, as a consequence of their higher Xammability and, hence, presumably higher propensity to recurrent Wre. Results conWrm the predictions and show that habitat Wltering driven by Wre may be detected even in local communities from an already Wre-Wltered regional Xora. They also provide a new perspective from which to consider a preponderant role of Wre as a key evolutionary force in acid, infertile Mediterranean heathlands.This work has been partially supported by projects VAMPIRO (CGL2008-05289-C02-01/BOS) and PERSIST (CGL2006-07126/BOS), Wnanced by the Spanish Ministerio de Ciencia e Innovación, and project P07-RNM-02869, Wnanced by the Junta de Andalucía regional government (Spain). Fieldwork was carried out under permission and complied with legal requirements of the Andalusian regional government.Peer reviewe

Nonlinear time-domain macromodeling of OTA circuits

The authors present an accurate nonlinear macromodel of the operational transconductance amplifier (OTA) which is suitable for the transient simulation of OTA-based CMOS analog integrated circuits. As compared to device-level OTA models, the proposed macromodel is advantageous in terms of CPU time. Also, in circuits with many OTAs, it does not have the problems of convergence that the device-level MODEL has. All the macromodel parameters can be calculated from measurements made at the OTA terminals. Experimental results from a 3-μm CMOS OTA prototype as well as simulation results from device-level models are included and compared to simulation results from the macromodel

Inference by replication in densely connected systems

An efficient Bayesian inference method for problems that can be mapped onto dense graphs is presented. The approach is based on message passing where messages are averaged over a large number of replicated variable systems exposed to the same evidential nodes. An assumption about the symmetry of the solutions is required for carrying out the averages; here we extend the previous derivation based on a replica symmetric (RS) like structure to include a more complex one-step replica symmetry breaking (1RSB)-like ansatz. To demonstrate the potential of the approach it is employed for studying critical properties of the Ising linear perceptron and for multiuser detection in Code Division Multiple Access (CDMA) under different noise models. Results obtained under the RS assumption in the non-critical regime give rise to a highly efficient signal detection algorithm in the context of CDMA; while in the critical regime one observes a first order transition line that ends in a continuous phase transition point. Finite size effects are also observed. While the 1RSB ansatz is not required for the original problems, it was applied to the CDMA signal detection problem with a more complex noise model that exhibits RSB behaviour, resulting in an improvement in performance.Comment: 47 pages, 7 figure

Composite CDMA - A statistical mechanics analysis

Code Division Multiple Access (CDMA) in which the spreading code assignment to users contains a random element has recently become a cornerstone of CDMA research. The random element in the construction is particular attractive as it provides robustness and flexibility in utilising multi-access channels, whilst not making significant sacrifices in terms of transmission power. Random codes are generated from some ensemble, here we consider the possibility of combining two standard paradigms, sparsely and densely spread codes, in a single composite code ensemble. The composite code analysis includes a replica symmetric calculation of performance in the large system limit, and investigation of finite systems through a composite belief propagation algorithm. A variety of codes are examined with a focus on the high multi-access interference regime. In both the large size limit and finite systems we demonstrate scenarios in which the composite code has typical performance exceeding sparse and dense codes at equivalent signal to noise ratio.Comment: 23 pages, 11 figures, Sigma Phi 2008 conference submission - submitted to J.Stat.Mec