| 13171. |
- Martinez, A, et al.
(författare)
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A study of band to band tunneling with application to high-field transport in hexagonal SiC polytypes
- 2001
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Ingår i: 3rd European Conference on Silicon Carbide and Related Materials KLOSTER BANZ, GERMANY, SEP, 2000. - 0878498737 ; , s. 487-490
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Konferensbidrag (refereegranskat)abstract
- The band structure of hexagonal SiC polytypes has regions in the k-space where two or more energy bands are very close to each other. Tunneling of electrons (or holes) between bands due to a high electric field is one of the processes that may allow the electron to jump between energy bands. It is important to consider this effect in order to understand high-field transport properties in these polytypes. In this work we have used the two-band k·p approximation [1] to calculate the time-dependent tunneling probability for electron transitions between two bands using the approach of Krieger and Iafrate (KI) [2]. Electric field strengths between 0.1-4 MV/cm have been used to study the effect of tunneling. Drift times in the order of 10 fs have been considered, which is representative for the time between scattering events. We have applied the k·p approximation to different points in the Brillouin zone of 4H-SiC and proved that there is considerable tunneling between bands under realistic electric field strengths and scattering times.
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| 13172. |
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| 13173. |
- Martinez, A., et al.
(författare)
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Investigation of Quantum Effects on the Bloch Electron Velocity Around Closely Spaced Bands at High Electric Fields
- 2003
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 93:12, s. 9789-9796
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Tidskriftsartikel (refereegranskat)abstract
- In conventional Monte Carlo simulations of electron and hole transport in semiconductors, the possibility of electric-field induced interband transitions between scattering events is not taken into account. In this article we study the effects of interband transitions on the electron (or hole) velocity and on the distance traveled by the charge carrier. The resulting quantum velocity, defined as the expectation value of the velocity operator for a state which is a superposition of Bloch states, contains an average group velocity and a quantum interference term. We calculate these terms for two cases, namely, for a simple parameterized two-band k.p model and for hole motion in wurtzite GaN, and compare with the one-band group velocity used in the conventional Monte Carlo method. The results show that interband transitions around closely spaced energy bands, which may arise in crystals with relatively large unit cells, like wurtzite GaN and hexagonal and rhombohedral SiC polytypes, may have a major effect on the particle velocity and particle trajectory, and therefore constitute a major influence on, for instance, electrical breakdown.
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| 13174. |
- Martinez, A., et al.
(författare)
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Monte Carlo Study of hole mobility in Al doped 4H-SiC
- 2002
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:3, s. 1359-1364
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Tidskriftsartikel (refereegranskat)abstract
- The ohmic transport of holes in p-type Al-doped 4H-SiC samples is investigated using a Monte Carlo tool based on a full-potential band structure. The temperature and doping dependence of the hole mobility and its anisotropy are calculated and discussed from a physical point of view, where we stress the importance of considering two-band conduction. Acoustic and optical phonon scattering, as well as ionized and neutral impurity scattering, have been considered. The Monte Carlo program also considers incomplete ionization of impurity atoms compatible with an Al ionization energy of 0.2 eV.
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| 13175. |
- Martinez, Antonio, et al.
(författare)
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Scattering probabilities for multiband hole states at high electric fields and high collision rates in 4H-SiC
- 2004
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Ingår i: SILICON CARBIDE AND RELATED MATERIALS 2003, PTS 1 AND 2. - STAFA-ZURICH : TRANS TECH PUBLICATIONS LTD. ; , s. 1237-1240
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Konferensbidrag (refereegranskat)abstract
- The scattering probabilities for a multiband carrier wave function have been studied for hole transport in 4H-SiC. During the drift at high electric fields it is possible to find the carriers with almost equal probability in two neighboring bands. In contrast to the standard Monte Carlo procedure, a possible interference between the components of the wave function in different bands appears in the calculation of the scattering probabilities when the time between scattering events is short. An important role is played by the overlap integral, which forbids this interference in some regions of the epsilon-k (energy-wavevector) space. We compare the results obtained using the true overlap integrals calculated from the wave functions with the common assumption, in which the overlap integral is assumed equal to one. Different scattering mechanisms, such as polar-optical phonon and intervalley optical phonon are studied. The model includes a spread in energy according to the Heisenberg uncertainty principle at short times. We have calculated the final state probability distribution considering the whole Brillouin zone of 4H-SiC for a particular set of initial states.
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| 13176. |
- Martinez-Assucena, A., et al.
(författare)
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Rehabilitation for multiple sclerosis, in adults (II); management and impact on impairment, functioning, and quality of life : An overview
- 2010
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Ingår i: Critical Reviews in Physical and Rehabilitation Medicine. - 0896-2960. ; 22:1-4, s. 179-240
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Tidskriftsartikel (refereegranskat)abstract
- Multiple sclerosis (MS) often leads to different levels of severity and progression of impairment and disability and to dissimilar levels of limitation in activities and participation in different social domains, with varying impacts on quality of life (QoL) among people with MS (PwMS). Results have shown that, for PwMS, prioritizing goal setting may enhance adherence to treatment. Interdisciplinary rehabilitation may prolong the functional status level of PwMS, may result in transient improvement in the aspects of impairment features, may increase their participation in activities, and may improve their QoL, even when disease progression is not modified. Single rehabilitation packages of comprehensive care have proven beneficial, such as physiotherapy, which enhances aerobic capacity, strength, pain, mood, mobility, and QoL. Occupational therapy can help reduce the impact of impairment on QoL, especially fatigue. Neuropsychological interventions, such as learning and memory remediation, psychological intervention for depressive disorders, and acquistion of coping skills and self-management techniques help PwMS to adjust to disease and disability. Speech therapy can improve intelligibility of communication. Learning swallowing techniques can help prevent material from entering the airway. Clean intermittent self-catheterization can help prevent urinary tract infections. Power wheelchairs enhance occupational performance and energy conservation. Further vocational rehabilitation settings and research are required for more appropriate interventions due to high unemployment rates among PwMS. Comprehensive care for PwMS should include planning for future independent living and long-term care needs.
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| 13177. |
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| 13178. |
- Martinez, MN, et al.
(författare)
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Grado de conocimientos y actitudes de la enfermería de la Comunidad Autónoma de Madrid (CAM) ante el dolor: Diplomados en enfermería y profesionales
- 2012
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Ingår i: Revista de la Sociedad Española del Dolor. - 1134-8046 .- 2254-6189. ; 19:6, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- The pain has become the fifth vital sign and is now a critical issue in patient care. Effective treatment of it is still one of the most important and urgent health care system in developed countries worldwide. While pain in patients is a very in vogue these days, however, which is unchallenged is the education of future nursing professionals in the care of such patients. The study and treatment of pain should be instilled in nursing students in their training, both theoretical and practical. The work is very important that teachers also take on the subject. The challenge for the nursing profession in this field would you organize, structure and support a program involving the activation of educational programs for students and practicing nurses. To start our research we made an analysis on the one hand, the current curricula of different schools of nursing in the CAM, with subjects with pain content, analyzing the similarity or not between them, the treated sections, etc. all this curriculum outline compared to the IASP (International Association of Study of Pain) proposed for nursing studies and, secondly, we describe the knowledge and attitudes of both groups in nursing to pain, both professional and qualified nurses. To observe the degree of knowledge and attitudes towards pain in both groups, was introduced as a tool the NKAS-RP (Nurses' Knowledge and Attitudes Survey Regarding Pain). The working group is proposed, therefore, three general objectives: The first description of the curricula of the courses in the career of nursing content in pain, and el2 and 3 goals, define the knowledge and attitudes to pain nursing students and nurses of the CAM. This is a descriptive, observational, multicenter, randomized, which analyzes the current knowledge and attitudes of the nursing staff, both among students (future graduates in nursing) and among professionals. Was carried out between 2008 and 2010, used to publicize the results of the statistical package SPSS version 17.0. As results were obtained, as in previous studies, worldwide, a poor knowledge of pain and a bad attitude before that symptom. It is proposed to improve: in the case of students, changes in the curriculum of the Diploma (future degree) nurses, and in the case of professionals, continuing education and refresher courses in that subject.
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| 13179. |
- Martinez Rau, Luciano, et al.
(författare)
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Real-Time Acoustic Monitoring of Foraging Behavior of Grazing Cattle Using Low-Power Embedded Devices
- 2023
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Ingår i: 2023 IEEE Sensors Applications Symposium (SAS). - : IEEE conference proceedings. - 9798350323078
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Konferensbidrag (refereegranskat)abstract
- Precision livestock farming allows farmers to optimize herd management while significantly reducing labor needs. Individualized monitoring of cattle feeding behavior offers valuable data to assess animal performance and provides valuable insights into animal welfare. Current acoustic foraging activity recognizers achieve high recognition rates operating on computers. However, their implementations on portable embedded systems (for use on farms) need further investigation. This work presents two embedded deployments of a state-of-the-art foraging activity recognizer on a low-power ARM Cortex-M0+ microcontroller. The parameters of the algorithm were optimized to reduce power consumption. The embedded algorithm processes masticatory sounds in real-time and uses machine-learning techniques to identify grazing, rumination and other activities. The overall classification performance of the two embedded deployments achieves an 84% and 89% balanced accuracy with a mean power consumption of 1.8 mW and 12.7 mW, respectively. These results will allow this deployment to be integrated into a self-powered acoustic sensor with wireless communication to operate autonomously on cattle.
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| 13180. |
- Martinez Rau, Luciano S., et al.
(författare)
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Daylong acoustic recordings of grazing and rumination activities in dairy cows
- 2023
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Ingår i: Scientific Data. - : Springer Nature. - 2052-4463. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring livestock feeding behavior may help assess animal welfare and nutritional status, and to optimize pasture management. The need for continuous and sustained monitoring requires the use of automatic techniques based on the acquisition and analysis of sensor data. This work describes an open dataset of acoustic recordings of the foraging behavior of dairy cows. The dataset includes 708 h of daily records obtained using unobtrusive and non-invasive instrumentation mounted on five lactating multiparous Holstein cows continuously monitored for six non-consecutive days in pasture and barn. Labeled recordings precisely delimiting grazing and rumination bouts are provided for a total of 392 h and for over 6,200 ingestive and rumination jaw movements. Companion information on the audio recording quality and expert-generated labels is also provided to facilitate data interpretation and analysis. This comprehensive dataset is a useful resource for studies aimed at exploring new tools and solutions for precision livestock farming.
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