Shot Noise in Magnetic Tunnel Junctions: Evidence for Sequential Tunneling

We report the experimental observation of sub-Poissonian shot noise in single magnetic tunnel junctions, indicating the importance of tunneling via impurity levels inside the tunnel barrier. For junctions with weak zero-bias anomaly in conductance, the Fano factor (normalized shot noise) depends on the magnetic configuration being enhanced for antiparallel alignment of the ferromagnetic electrodes. We propose a model of sequential tunneling through nonmagnetic and paramagnetic impurity levels inside the tunnel barrier to qualitatively explain the observations.Comment: 5 pages, 5 figure

Conductance in Co/Al2O3/Si/Al2O3 permalloy with asymmetrically doped barrier

Permalloy magnetic tunnel junctions. Complementary low frequency noise measurements are used to understand the conductance results. The obtained data indicate the breakdown of the Coulomb blockade for thickness of the asymmetric silicon layer exceeding 1.2\AA . The crossover in the conductance, the dependence of the tunnelling magnetoresistance with the bias voltage and the noise below 80K correspond to 1 monolayer coverage. Interestingly, the zero bias magnetoresistance remains nearly unaffected by the presence of the silicon layer. The proposed model uses Larkin-Matveev approximation of tunnelling through a single impurity layer generalized to 3D and takes into account the variation of the barrier shape with the bias voltage. The main difference is the localization of all the impurity levels within a single atomic layer. In the high thickness case, up to 1.8\AA, we have introduced a phenomenological parameter, which reflects the number of single levels on the total density of silicon atoms.Comment: 10 pages, 13 figure

Extracción de características de imagen para recuperación 3D

La reconstrucción 3D a partir de imágenes 2D es un desafíıo en el campo de imágenes y visión, con múltiples aplicaciones en áreasmuy diversas. Algunos métodos se basan en marcadores, los cuales son puntos estratégicamente ubicados en el objeto de interés o sobre el trajede un ser humano, diseñado para este propósito. A diferencia de estos métodos, este trabajo se enfoca en encontrar caracteríısticas en imágenes2D las cuales pueden ser utilizadas como marcadores, permitiendo la reconstrucción 3D automáticamente. Utilizamos el método SIFT (ScaleInvariant Feature Transform) para asociar puntos característicos en imágenes de la misma escena provenientes de diferentes puntos de vista. Nos encontramos mejorando el proceso por medio del reconocimiento de skeletons. El objetivo de este trabajo es que los puntos encontrados seutilicen para estimar estructuras 3D. Los resultados obtenidos hasta el momento son alentadores.Sociedad Argentina de Informática e Investigación Operativ

Lung cancer in HIV-infected patients

Purpose: Several studies have shown that HIV patients are at higher risk of lung cancer. Our aim is to analyse the prevalence and features of lung cancer in HIV-infected patients. Methods: The clinical charts of 4,721 HIV-infected patients seen in three hospitals of southeast Spain (study period 1992–2012) were reviewed, and all patients with a lung cancer were analysed. Results: There were 61 lung cancers, giving a prevalence of 1.2%. There was a predominance of men (82.0%), and smokers (96.6%; mean pack-years 35.2), with a median age of 48.0 (41.7–52.9) years, and their distribution according to risk group for HIV was: intravenous drug use 58.3%, homosexual 20.0%, and heterosexual 16.7%. Thirty-four (56.7%) patients were Aids cases, and 29 (47.5%) had prior pulmonar events: tuberculosis 16, bacterial pneumonia 9, and P. jiroveci pneumonia 4. The median nadir CD4 count was 149/mm3 (42–232), the median CD4 count at the time of diagnosis of the lung cancer was 237/mm3 (85–397), and 66.1%<350/mm3. 66.7% were on ART, and 70% of them had undetectable HIV viral load. The most common histological types of lung cancer were adenocarcinoma and epidermoid, with 24 (40.0%) and 23 (38.3%) cases, respectively. There were 49 (80.3%) cases with advanced stages (III and IV) at diagnosis. The distribution of treatments was: only palliative 23 (39.7%), chemotherapy 14 (24.1%), surgery and chemotherapy 8 (13.8%), radiotherapy 7 (12.1%), surgery 4 (6.9%), and other combined treatments 2 (3.4%). Forty-six (76.7%) patients died, with a median survival time of 3 months. The Kaplan-Meier survival rate at 6 months was 42.7% (at 12 months 28.5%). Conclusions: The prevalence of lung cancer in this cohort of HIV-patients is high. People affected are mainly men, smokers, with transmission of HIV by intravenous drug use, and around half of them with prior opportunistic pulmonary events. Most patients had low nadir CD4 count, and were immunosuppressed at the time of diagnosis. Adenocarcinoma is the most frequent histological type. The diagnosis is usually made at advanced stages of the neoplasm, and mortality is high

Real world preventative drug management of migraine among Spanish neurologists

BACKGROUND: Many different preventatives have showed efficacy in the treatment of migraine. National guidelines differ in their recommendations and patients' characteristics are usually taken into account in their selection. In Spain, real life use of preventive therapies seems to be heterogeneous. We aimed to evaluate differences in clinical practice and adherence to national guidelines among Spanish neurologists. METHODS: Observational descriptive study. A survey was conducted among neurologists ascribed to the Spanish Society of Neurology. Participants were differentiated in accordance with their dedication to headache disorders. We analysed socio-demographic parameters and evaluated 43 questions considering migraine management as well as therapeutic choices regarding migraine sub-types and finally, neurologists' personal perception. RESULTS: One hundred fifty-five neurologists participated from 17 different regions, 43.4% of them female and 53.3% under 40¿years of age. 34.9% confirmed headache disorders as their main interest. The first choice for preventive therapy in chronic migraine among participants was topiramate (57%) followed by amytriptiline (17.9%) and beta-blockers (14.6%). However in episodic migraine, the preferred options were beta-blockers (47.7%), topiramate (21.5%) and amytriptiline (13.4%). Regarding perceived efficacy, topiramate was considered the best option in chronic migraine (42.7%) followed by onabotulinumtoxinA (25.5%) and amitryptiline (22.4%). Where episodic migraine was concerned, surveyed neurologists perceived topiramate (43.7%) and beta-blockers (30.3%) as the best options. When we evaluated the duration of treatment use with a view to adequate therapeutic response, 43.5% of neurologists preferred 3¿months duration and 39.5% were in favour of 6¿months duration in episodic migraine. However, considering the preferred duration of treatment use in chronic migraine, 20.4% recommended 3¿months, 42.1% preferred 6¿months and 12.5% and 22.4% opted for 9 and 12¿months respectively. When considering onabotulinumtoxinA therapy, the number of prior therapeutic failures was zero in 7.2% of neurologists, one in 5.9%, two in 44.1%, three in 30.9% and four or more in 11.9%. Following an initial treatment failure with onabotulinumtoxinA, 49% of subjects decided against a second treatment. The number of OnabotA procedures before considering it as ineffective was two in 18.9% of neurologists, three in 70.8% and four in 10.4%. CONCLUSIONS: The initial management of migraine among Spanish Neurologists is in line with most guidelines, where first choice preventative drugs are concerned. The Management of episodic migraine differed from chronic migraine, both in terms of neurologist preference and in their perceived efficacy

Real-world preventative drug management of Chronic Migraine among Spanish Neurologists

O42 Background: In migraine, the therapeutic preventive drug arsenal is varied. Whenprescribing both Guidelines and patient characteristics are taken intoaccount. In Spain, the use of preventive therapies seems to beheterogeneous.The objective of this study was to evaluate real-life clinical prescribingpractice amongst neurologists in Spain Methods: Observational descriptive study done with a survey by Neurologistsof the Spanish Neurological Society (SEN). Neurologists who participatedwere divided into Headache Specialists or not. The followingdata was collected: socio-demographic data, ; preventive treatmentand choices different migraine sub-types, and their personal perceptionof efficacy and tolerability to different drugs. Results: We analyzed 152 surveys from neurologists around our country.From them: 43.4% were female, 53.3% <40 years, and 34.9% were interestedin headache .In regards to preventive treatment choice; in chronic migraine topiramate(57%) amytriptiline (17.9%) and beta-blockers (14.6%), whereasin episodic migraine the preferred drugs were beta-blockers (47.7%), topiramate (21.5%) and amytriptiline (13.4%).Regarding perceived efficacy, topiramate was considered the bestoption in chronic migraine (42.7%) followed by onabotulinumtoxinA(25.5%) and amitryptiline (22.4%). In episodic migraine, neurologistpreferred topiramate (43.7%) and beta-blockers (30.3%).Regarding the duration of preventive therapy when improvementwas achieved, when treating episodic migraine 43.5% of the surveyedneurologists recommended 3 months and 39.5% preferred 6months. When they treated chronic migraine, 20.4% of neurologistsrecommended 3 months, 42.1% 6 months, 12.5% 9 months and22.4% preferred to maintain treatment during 12 months.When considering onabotulinumtoxinA treatment, the number ofprior therapeutical failures was cero in 7.2% of surveyed, one in5.9%, two in 44.1%, three in 30.9%, and four or more in 11.9%. Theincrease of OnabotulinumtoxinA dose up to 195 UI was consideredby 51% of neurologists after a first ineffective procedure, by 42.2% after two injections, and by 83% after a third infiltration. Surveyedcolleagues admitted to take into account in their decisions mainlypatient comorbidities (70.2%) rather than guidelines (13.9%). Conclusions: Initial management of Migraine among Spanish Neurologists is madewith the preventative drugs which are considered as first choices inmost of the guidelines. Management of episodic migraine differedfrom chronic migraine, both in the order or drugs and the perceptionof the most effective therapy

Design and implementation of multiprotocol framework for residential prosumer incorporation in flexibility markets

The growth of distributed renewable energy in the electrical grid presents challenges to its stability and quality. To address this at the local level, flexibility energy strategies emerge as an innovative technique. However, managing these strategies in residential areas becomes complex due to the unique characteristics of each prosumer. A major challenge lies in managing communication among diverse devices with different protocols. To address these issues, a comprehensive framework is designed and implemented to facilitate prosumers' integration in flexibility strategies, addressing communication at various levels. The effectiveness of the proposed framework is demonstrated through its implementation in a real smart home environment with diverse devices. The framework enables seamless integration and communication between IoT devices and IEC 61,850-compliant power devices. This research presents a novel approach to address the challenges of managing flexibility strategies in residential areas, providing a practical solution for prosumers to actively participate in optimizing energy consumption and enhancing the stability and quality of the electricity system amidst the growing integration of distributed renewable energy.</p

RASPV: A robotics framework for augmented simulated prosthetic vision

One of the main challenges of visual prostheses is to augment the perceived information to improve the experience of its wearers. Given the limited access to implanted patients, in order to facilitate the experimentation of new techniques, this is often evaluated via Simulated Prosthetic Vision (SPV) with sighted people. In this work, we introduce a novel SPV framework and implementation that presents major advantages with respect to previous approaches. First, it is integrated into a robotics framework, which allows us to benefit from a wide range of methods and algorithms from the field (e.g. object recognition, obstacle avoidance, autonomous navigation, deep learning). Second, we go beyond traditional image processing with 3D point clouds processing using an RGB-D camera, allowing us to robustly detect the floor, obstacles and the structure of the scene. Third, it works either with a real camera or in a virtual environment, which gives us endless possibilities for immersive experimentation through a head-mounted display. Fourth, we incorporate a validated temporal phosphene model that replicates time effects into the generation of visual stimuli. Finally, we have proposed, developed and tested several applications within this framework, such as avoiding moving obstacles, providing a general understanding of the scene, staircase detection, helping the subject to navigate an unfamiliar space, and object and person detection. We provide experimental results in real and virtual environments. The code is publicly available at https://www.github.com/aperezyus/RASP

Sistema de realidad virtual para exploración 3D con visión protésica simulada

Recent advances in visual prostheses have demonstrated that it is possible to restore part of the vision in certain cases of visual impairment, yet with limitations such as low resolution or a reduced field of view. To experiment more easily, visual prosthesis simulators (VPS) are used. An immersive, flexible and realistic SPV is presented using a virtual reality system, so that environments created by a computer can be explored by integrating the real movement of the user's head in the simulation thanks to the virtual reality goggles Oculus Rift DK2 and allowing a movement through the scenario using a controller or joystick in order to explore the environment as completely and realistically as possible.Los recientes avances en las prótesis visuales han demostrado que es posible restaurar parte de la visión en determinados casos de deficiencia visual, aunque con limitaciones como la baja resolución o un campo de visión reducido. Para experimentar más fácilmente se utilizan los simuladores de prótesis visuales (SPV). Se presenta un SPV inmersivo, flexible y realista mediante un sistema de realidad virtual, de forma que se puedan explorar entornos creados por un ordenador integrando el movimiento real de la cabeza del usuario en la simulación gracias a las gafas de realidad virtual Oculus Rift DK2 y permitiendo un desplazamiento por el escenario mediante un mando o joystick para poder explorar el entorno de la forma más completa y realista posible

The Term Equity in Education: A Literature Review with Scientific Mapping in Web of Science

In this section you can acknowledge any support given which is not covered by the author contribution or funding sections. This may include administrative and technical support, or donations in kind (e.g., materials used for experiments).The term “equity” (EQUI) is a complex concept to be defined, because it depends on many factors, mainly political ideals. The objective of this research is to determine the evolution and development of the term equity in education by the scientific community. The main objective is to identify the scientific production and performance of the term equity in the field of education. The research method developed is based on bibliometrics, specifically on the technique of scientific mapping, and a process of quantification, analysis, evaluation and estimation of scientific documents was developed. The results indicate there is no established line of research or strong connections between the themes. This shows the existing variety of research on the term equity. Thus, the trend in research on the term equity is focused on the early periods of study on the students’ diversity in order to evolve to more concrete and specific aspects of equity, such as gender and race. It is concluded that the theoretical framework of reference shows how equity should be incorporated into the education system under the parameters of equal opportunities, of equality in access to higher education, regardless of gender or socio-cultural background.Proyecto de investigacion I+D Reference: ISPRS-2017-2021Corporacion Escuela Tecnologica del Oriente y Secretaria de Educacion de Santander (Colombia) & University of Granad