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1.
Faraday Discuss ; 199: 129-158, 2017 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-28436506

RESUMEN

The electrostatic interaction between two charged particles is strongly modified in the vicinity of a metal. This situation is usually accounted for by the celebrated image charges approach, which was further extended to account for the electronic screening properties of the metal at the level of the Thomas-Fermi description. In this paper we build upon a previous approach [M. A. Vorotyntsev and A. A. Kornyshev, Zh. Eksp. Teor. Fiz., 1980, 78(3), 1008-1019] and successive works to calculate the 1-body and 2-body electrostatic energy of ions near a metal in terms of the Thomas-Fermi screening length. We propose workable approximations suitable for molecular simulations of ionic systems close to metallic walls. Furthermore, we use this framework to calculate analytically the electrostatic contribution to the surface energy of a one dimensional crystal at a metallic wall and its dependence on the Thomas-Fermi screening length. These calculations provide a simple interpretation for the surface energy in terms of image charges, which allows for an estimation of the interfacial properties in more complex situations of a disordered ionic liquid close to a metal surface. The counter-intuitive outcome is that electronic screening, as characterized by a molecular Thomas-Fermi length lTF, profoundly affects the wetting of ionic systems close to a metal, in line with the recent experimental observation of capillary freezing of ionic liquids in metallic confinement.

2.
BMC Vet Res ; 13(1): 21, 2017 Jan 13.
Artículo en Inglés | MEDLINE | ID: mdl-28086880

RESUMEN

BACKGROUND: In 2008, a program to eradicate bovine virus diarrhea (BVD) in cattle in Switzerland was initiated. After targeted elimination of persistently infected animals that represent the main virus reservoir, the absence of BVD is surveilled serologically since 2012. In view of steadily decreasing pestivirus seroprevalence in the cattle population, the susceptibility for (re-) infection by border disease (BD) virus mainly from small ruminants increases. Due to serological cross-reactivity of pestiviruses, serological surveillance of BVD by ELISA does not distinguish between BVD and BD virus as source of infection. RESULTS: In this work the cross-serum neutralisation test (SNT) procedure was adapted to the epidemiological situation in Switzerland by the use of three pestiviruses, i.e., strains representing the subgenotype BVDV-1a, BVDV-1h and BDSwiss-a, for adequate differentiation between BVDV and BDV. Thereby the BDV-seroprevalence in seropositive cattle in Switzerland was determined for the first time. Out of 1,555 seropositive blood samples taken from cattle in the frame of the surveillance program, a total of 104 samples (6.7%) reacted with significantly higher titers against BDV than BVDV. These samples originated from 65 farms and encompassed 15 different cantons with the highest BDV-seroprevalence found in Central Switzerland. On the base of epidemiological information collected by questionnaire in case- and control farms, common housing of cattle and sheep was identified as the most significant risk factor for BDV infection in cattle by logistic regression. CONCLUSION: This indicates that pestiviruses from sheep should be considered as a source of infection of domestic cattle and might well impede serological BVD surveillance.


Asunto(s)
Virus de la Enfermedad de la Frontera/aislamiento & purificación , Diarrea Mucosa Bovina Viral/prevención & control , Virus de la Diarrea Viral Bovina/aislamiento & purificación , Animales , Antígenos Virales , Virus de la Enfermedad de la Frontera/genética , Diarrea Mucosa Bovina Viral/epidemiología , Estudios de Casos y Controles , Bovinos , Células Cultivadas , Virus de la Diarrea Viral Bovina/genética , Modelos Logísticos , Estudios Seroepidemiológicos , Pruebas Serológicas , Suiza/epidemiología , Cornetes Nasales/citología
3.
Phys Rev Lett ; 115(3): 037201, 2015 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-26230822

RESUMEN

The Wien effect is a model process for field-induced charge creation. Here it is derived for a nonelectrical system: the spin ice "magnetolyte"-a unique system showing perfect charge symmetry. An entropic reaction field, analogous to the Jaccard field in ice, opposes direct current, but a frequency window exists in which the Wien effect for magnetolyte and electrolyte are indistinguishable. The universal enhancement of monopole density speeds up the magnetization dynamics, which manifests in the nonlinear, nonequilibrium ac susceptibility. This is a rare instance where such effects may be calculated, providing new insights for electrolytes. Experimental predictions are made for Dy2Ti2O7 spin ice.

4.
Nat Mater ; 12(11): 1033-7, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23934036

RESUMEN

The second Wien effect describes the nonlinear, non-equilibrium response of a weak electrolyte in moderate to high electric fields. Onsager's 1934 electrodiffusion theory, along with various extensions, has been invoked for systems and phenomena as diverse as solar cells, surfactant solutions, water splitting reactions, dielectric liquids, electrohydrodynamic flow, water and ice physics, electrical double layers, non-ohmic conduction in semiconductors and oxide glasses, biochemical nerve response and magnetic monopoles in spin ice. In view of this technological importance and the experimental ubiquity of such phenomena, it is surprising that Onsager's Wien effect has never been studied by numerical simulation. Here we present simulations of a lattice Coulomb gas, treating the widely applicable case of a double equilibrium for free charge generation. We obtain detailed characterization of the Wien effect and confirm the accuracy of the analytical theories as regards the field evolution of the free charge density and correlations. We also demonstrate that simulations can uncover further corrections, such as how the field-dependent conductivity may be influenced by details of microscopic dynamics. We conclude that lattice simulation offers a powerful means by which to model and investigate system-specific corrections to the Onsager theory, and thus constitutes a valuable tool for detailed theoretical studies of the numerous practical applications of the second Wien effect.

5.
Sci Rep ; 13(1): 9952, 2023 06 19.
Artículo en Inglés | MEDLINE | ID: mdl-37336927

RESUMEN

Modifications in the epigenetic landscape have been considered a hallmark of cancer. Histone deacetylation is one of the crucial epigenetic modulations associated with the aggressive progression of various cancer subtypes. Herein, we have repurposed the neprilysin inhibitor sacubitrilat as a potent anticancer agent using in-silico protein-ligand interaction profiler (PLIP) analysis, molecular docking, and in vitro studies. The screening of PLIP profiles between vorinostat/panobinostat and HDACs/LTA4H followed by molecular docking resulted in five (Sacubitrilat, B65, BDS, BIR, and NPV) FDA-approved, experimental and investigational drugs. Sacubitrilat has demonstrated promising anticancer activity against colorectal cancer (SW-480) and triple-negative breast cancer (MDA-MB-231) cells, with IC50 values of 14.07 µg/mL and 23.02 µg/mL, respectively. FACS analysis revealed that sacubitrilat arrests the cell cycle at the G0/G1 phase and induces apoptotic-mediated cell death in SW-480 cells. In addition, sacubitrilat inhibited HDAC isoforms at the transcriptomic level by 0.7-0.9 fold and at the proteomic level by 0.5-0.6 fold as compared to the control. Sacubitrilat increased the protein expression of tumor-suppressor (p53) and pro-apoptotic makers (Bax and Bid) by 0.2-2.5 fold while decreasing the expression of anti-apoptotic Bcl2 and Nrf2 proteins by 0.2-0.5 fold with respect to control. The observed cleaved PARP product indicates that sacubitrilat induces apoptotic-mediated cell death. This study may pave the way to identify the anticancer potential of sacubitrilat and can be explored in human clinical trials.


Asunto(s)
Antineoplásicos , Epigénesis Genética , Neprilisina , Humanos , Antineoplásicos/farmacología , Apoptosis , Proteínas Reguladoras de la Apoptosis/metabolismo , Línea Celular Tumoral , Proliferación Celular , Reposicionamiento de Medicamentos , Simulación del Acoplamiento Molecular , Neprilisina/antagonistas & inhibidores , Proteómica
6.
Heredity (Edinb) ; 106(2): 339-47, 2011 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20551975

RESUMEN

We describe patterns of DNA sequence diversity in a newly identified sex-linked gene, SlX9/SlY9, in Silene latifolia (Caryophyllaceae). The copies on both sex chromosomes seem to be functional, and each maps close to the respective X- and Y-linked copy of another sex-linked gene pair, SlCypX/SlCypY. The Y-linked copy has low diversity, similar to what has been found for several other Y-linked genes in S. latifolia, and consistent with the theoretical expectations of hitch-hiking processes occurring on a non-recombining chromosome. However, SlX9 has higher diversity than other genes on the S. latifolia X chromosome. We evaluate the hypothesis of introgression from the closely related species S. dioica as an explanation for the high sequence diversity observed.


Asunto(s)
Cromosomas de las Plantas , Variación Genética , Cromosomas Sexuales , Silene/genética , Mapeo Cromosómico , Evolución Molecular , Haplotipos , Endogamia , Desequilibrio de Ligamiento
7.
Mol Ecol ; 18(8): 1716-29, 2009 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-19386035

RESUMEN

Global biodiversity peaks in the tropical forests of the Andes, a striking geological feature that has likely been instrumental in generating biodiversity by providing opportunities for both vicariant and ecological speciation. However, the role of these mountains in the diversification of insects, which dominate biodiversity, has been poorly explored using phylogenetic methods. Here we study the role of the Andes in the evolution of a diverse Neotropical insect group, the clearwing butterflies. We used dated species-level phylogenies to investigate the time course of speciation and to infer ancestral elevation ranges for two diverse genera. We show that both genera likely originated at middle elevations in the Andes in the Middle Miocene, contrasting with most published results in vertebrates that point to a lowland origin. Although we detected a signature of vicariance caused by the uplift of the Andes at the Miocene-Pliocene boundary, most sister species were parapatric without any obvious vicariant barrier. Combined with an overall decelerating speciation rate, these results suggest an important role for ecological speciation and adaptive radiation, rather than simple vicariance.


Asunto(s)
Biodiversidad , Mariposas Diurnas/genética , Especiación Genética , Filogenia , Altitud , Animales , Mariposas Diurnas/clasificación , Núcleo Celular/genética , ADN Mitocondrial/genética , Genes de Insecto , Modelos Genéticos , Análisis de Secuencia de ADN , América del Sur , Especificidad de la Especie
9.
J Leukoc Biol ; 68(6): 779-84, 2000 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-11129644

RESUMEN

Antimicrobial peptides are a prevalent mechanism of host defense found throughout nature. In mammals, defensins are among the most abundant of these broad-spectrum antibiotics, and are expressed in epithelial and hematopoietic cells. The defensin peptides are especially abundant in neutrophils; however, gene expression is limited to the promyelocyte stage. In epithelial cells, defensin genes are found as both constitutively expressed and inducible. Induction has been observed in vitro by stimulation with bacterial lipopolysaccharide as well as inflammatory mediators. In vivo, up-regulation of several defensin genes occurs in both infectious and inflammatory states. Gene regulation occurs via signal transduction pathways common to other innate immune responses, utilizing transcription factors such as nuclear factor (NF)-kappaB and NF interleukin-6. Together, the data suggest a broad-based innate host defense whereby potent antimicrobial peptides are present to prevent initial colonization by pathogenic microorganisms. In addition, the recognition of bacteria coupled with a nascent inflammatory response can bolster this defense by a coordinated up-regulation of the peptides.


Asunto(s)
Defensinas/biosíntesis , Regulación de la Expresión Génica , Mamíferos/genética , Factores de Transcripción , Animales , Proteína delta de Unión al Potenciador CCAAT , Proteínas Potenciadoras de Unión a CCAAT , Cromosomas Humanos Par 8/genética , Defensinas/química , Defensinas/clasificación , Defensinas/genética , Sistema Digestivo/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Inmunidad Innata , Infecciones/genética , Infecciones/metabolismo , Inflamación/genética , Inflamación/metabolismo , Lipopolisacáridos/farmacología , Mamíferos/metabolismo , Familia de Multigenes , FN-kappa B/metabolismo , Neutrófilos/metabolismo , Especificidad de Órganos , Sistema Respiratorio/metabolismo , Transducción de Señal/efectos de los fármacos
10.
J Clin Epidemiol ; 49(12): 1401-5, 1996 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-8970490

RESUMEN

We investigated the value of the ankle-brachial systolic pressure index (ABPI) as a test for the diagnosis of peripheral arterial occlusive disease (PAOD) in general practice. ABPI measurements on 231 legs of 117 subjects performed in three general practice centers (GPC) were compared with the diagnostic conclusions of a Vascular Laboratory. The optimum cutoff value for the ABPI, its accuracy and diagnostic value were estimated. In a subpopulation of 51 subjects for whom repeated measurements were available, we checked whether taking the mean of three consecutive ABPIs for test outcome would enhance diagnostic performance. Receiver Operating Characteristic analysis showed that overall performance of the GPC ABPI was good (area under the curve approximately 0.9). Performing repeated ABPI measurements was superior to performing a single measurement. The optimum cutoff value for the ABPI was 0.97, associated with a diagnostic odds ratio (OR) of 17 and an accuracy of 81%. In a somewhat more selected subpopulation, the optimum cutoff value was 0.92 (OR 70, accuracy 90%). On the basis of our results, we suggest the following rule of thumb: if the ABPI < 0.8 or if the mean of three ABPIs < 0.9, it is highly probable that PAOD is present (PV+ > or = 95%); if the ABPI > 1.1 or if the mean of three ABPIs > 1.0, PAOD can be ruled out (PV- > or = 99%). In conclusion, in primary health care, the ABPI measurement can be a useful supplementary test in ambiguous diagnostic situations with regard to PAOD.


Asunto(s)
Tobillo/irrigación sanguínea , Brazo/irrigación sanguínea , Arteriopatías Oclusivas/diagnóstico , Determinación de la Presión Sanguínea/métodos , Presión Sanguínea , Atención Primaria de Salud , Adulto , Anciano , Anciano de 80 o más Años , Arteriopatías Oclusivas/fisiopatología , Arteria Braquial/fisiología , Femenino , Humanos , Flujometría por Láser-Doppler , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Valor Predictivo de las Pruebas , Curva ROC , Reproducibilidad de los Resultados , Sístole
11.
Int J Epidemiol ; 25(2): 282-90, 1996 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-9119553

RESUMEN

BACKGROUND: The prevalence of peripheral arterial occlusive disease (PAOD), including asymptomatic cases and cases unknown to the general practitioner (GP) was estimated in 18,884 men and women, aged 45-74 years, on the list of 18 general practice centres (GPC). METHODS: The study population (n = 3171) consisted of a stratified sample of the total population. In the GPC data were collected on intermittent claudication (IC), peripheral pulses, vascular risk factors, cardio- and cerebrovascular disease (CCVD) and the ankle brachial systolic pressure ratio (AB ratio) and PAOD was defined as an AB ratio < 0.95 on two consecutive occasions. Results were recalculated for the total population. RESULTS: The prevalence of PAOD was 6.9 percent (95 percent Cl:5.2-7.9 percent), a quarter of which (1.6 percent) met the classic WHO criteria. Peripheral arterial occlusive disease did not occur significantly more often among men than among women but men suffered more often from an advanced stage of PAOD. Of all PAOD cases, 22 percent were symptomatic. The proportion of symptomatic cases correlated positively with higher age, male gender and lower AB ratio. Among asymptomatic PAOD cases the prevelance of concomitant CCVD was three to four times as high as in the group of subjects without PAOD. Of all PAOD cases 68 percent were unknown to the GP and this group mainly represented less advanced cases of atherosclerosis. However, among PAOD cases with an AB ratio <0.75, 42 percent were unknown to the GP. CONCLUSIONS: Our data on asymptomatic and unknown PAOD cases show that GPs can still enhance their efforts towards (secondary) prevention of atherosclerosis.


Asunto(s)
Arteriopatías Oclusivas/epidemiología , Medicina Familiar y Comunitaria , Enfermedades Vasculares Periféricas/epidemiología , Adulto , Anciano , Arteriopatías Oclusivas/diagnóstico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Países Bajos/epidemiología , Enfermedades Vasculares Periféricas/diagnóstico , Vigilancia de la Población , Prevalencia , Factores de Riesgo , Encuestas y Cuestionarios
12.
Med Decis Making ; 17(1): 61-70, 1997.
Artículo en Inglés | MEDLINE | ID: mdl-8994152

RESUMEN

OBJECTIVES: To assess the diagnostic values of single and combined data from the history, physical examination, and medical record with regard to peripheral arterial occlusive disease (PAOD) in patients with leg complaints; to construct a multivariable model for the clinical diagnosis of PAOD by primary care physicians. SETTING: 18 general practice centers in The Netherlands. DESIGN: Cross-sectional comparison of signs, symptoms, and data from the medical record with the independently assessed ankle-brachial systolic pressure index (ABPI; cutoff point < 0.90); analysis: bivariate, multiple logistic regression (MLR). POPULATION: 2,455 individuals with leg complaints, aged 40.7-78.4 years; ABPI < 0.90 present in 9.2% of legs (11.7% of individuals). OUTCOME MEASURES: Clinical variables: sensitivity, specificity, positive and negative predictive values (PV+, PV-), diagnostic odds ratio (OR); models: likelihood ratio test, area under the receiver operating characteristic curve (AUC). RESULTS: Bivariate analysis: highest sensitivity: age more than 60 years (77.3%); highest specificity: wounds or sores on toes and foot (99.7%); highest PV+: typical intermittent claudication (IC) (45.0%) (abnormal foot pulses 41.3%); highest PV-: strong pulses of both foot arteries (97.7%). MRL: the best-performing model (AUC 0.89) consisted of ten clinical variables: gender (OR 1.5), age more than 60 (OR 2.2); IC (OR 3.5); palpation of the skin temperature of the feet (OR 2.5), palpation of both foot pulses [OR 16.4 (abnormal) and 7.0 (doubtful)], auscultation of the femoral artery (OR 3.5); previous diagnosis of IHD (OR 1.7) or diabetes (OR 1.6), history of smoking (OR 2.1), and elevated blood pressure (OR 1.5). The range of predicted probabilities was 0.4-98%. The Hosmer-Lemeshow goodness-of-fit test indicated good overall fit (p = 52). CONCLUSIONS: Palpation of both foot pulses is the key procedure for the clinical diagnosis of PAOD. Traditional clinical evaluation enables the general practitioner to exclude the diagnosis of PAOD in many individuals with a high degree of certainly, to establish the diagnosis in a small group of patients, and to define a limited group of patients where supplementary noninvasive testing is appropriate. The MLR model can be used as a diagnostic checklist and as a reference for the physician's clinical hypothesis.


Asunto(s)
Arteriopatías Oclusivas/diagnóstico , Anamnesis/estadística & datos numéricos , Examen Físico/estadística & datos numéricos , Adulto , Anciano , Arteriopatías Oclusivas/epidemiología , Estudios Transversales , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Países Bajos/epidemiología , Oportunidad Relativa , Valor Predictivo de las Pruebas , Atención Primaria de Salud , Análisis de Regresión
13.
Aktuelle Traumatol ; 24(1): 35-7, 1994 Feb.
Artículo en Alemán | MEDLINE | ID: mdl-8165958

RESUMEN

Over and above the medical problems, AIDS also presents manifold and likewise still mostly undecided or at least not yet uniformly rated aspects. This article is a roughly sketched attempt at reviewing a few essential complexes at the interface between accident surgery and statutory accident insurance. Special attention is drawn to the update addendum.


Asunto(s)
Síndrome de Inmunodeficiencia Adquirida/prevención & control , Transfusión Sanguínea/legislación & jurisprudencia , Consentimiento Informado/legislación & jurisprudencia , Mala Praxis/legislación & jurisprudencia , Heridas y Lesiones/cirugía , Serodiagnóstico del SIDA/legislación & jurisprudencia , Síndrome de Inmunodeficiencia Adquirida/transmisión , Alemania , Humanos , Seguro por Accidentes/legislación & jurisprudencia , Responsabilidad Legal , Factores de Riesgo
14.
J Neural Eng ; 11(3): 035011, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24835837

RESUMEN

OBJECTIVE: Assimilating the diagnosis complete spinal cord injury (SCI) takes time and is not easy, as patients know that there is no 'cure' at the present time. Brain-computer interfaces (BCIs) can facilitate daily living. However, inter-subject variability demands measurements with potential user groups and an understanding of how they differ to healthy users BCIs are more commonly tested with. Thus, a three-class motor imagery (MI) screening (left hand, right hand, feet) was performed with a group of 10 able-bodied and 16 complete spinal-cord-injured people (paraplegics, tetraplegics) with the objective of determining what differences were present between the user groups and how they would impact upon the ability of these user groups to interact with a BCI. APPROACH: Electrophysiological differences between patient groups and healthy users are measured in terms of sensorimotor rhythm deflections from baseline during MI, electroencephalogram microstate scalp maps and strengths of inter-channel phase synchronization. Additionally, using a common spatial pattern algorithm and a linear discriminant analysis classifier, the classification accuracy was calculated and compared between groups. MAIN RESULTS: It is seen that both patient groups (tetraplegic and paraplegic) have some significant differences in event-related desynchronization strengths, exhibit significant increases in synchronization and reach significantly lower accuracies (mean (M) = 66.1%) than the group of healthy subjects (M = 85.1%). SIGNIFICANCE: The results demonstrate significant differences in electrophysiological correlates of motor control between healthy individuals and those individuals who stand to benefit most from BCI technology (individuals with SCI). They highlight the difficulty in directly translating results from healthy subjects to participants with SCI and the challenges that, therefore, arise in providing BCIs to such individuals.


Asunto(s)
Interfaces Cerebro-Computador , Electroencefalografía/métodos , Potenciales Evocados Motores , Imaginación , Corteza Motora/fisiopatología , Parálisis/fisiopatología , Traumatismos de la Médula Espinal/fisiopatología , Adulto , Anciano , Algoritmos , Vértebras Cervicales/fisiopatología , Humanos , Persona de Mediana Edad , Parálisis/etiología , Parálisis/rehabilitación , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/rehabilitación , Análisis y Desempeño de Tareas , Vértebras Torácicas/fisiopatología , Interfaz Usuario-Computador
15.
Clin Neurophysiol ; 124(8): 1596-604, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23540418

RESUMEN

OBJECTIVE: We studied the activation of cortical motor and parietal areas during the observation of object related grasping movements. By manipulating the type of an object (realistic versus abstract) and the type of grasping (correct versus incorrect), we addressed the question how observing such object related movements influences cortical rhythmicity, especially the mu-rhythm, in the context of an "extended" human mirror neuron system (MNS). METHODS: Multichannel electroencephalogram (EEG) was recorded during the observation of different object-related grasping actions in twenty healthy subjects. Different movies were presented, showing sequences of correct or incorrect hand grasping actions related to an abstract or realistic (daily life) object. RESULTS: Event-related de/synchronization (ERD/ERS) analyses revealed a larger ERD in the upper alpha (10-12 Hz), beta (16-20 Hz) and gamma (36-40 Hz) frequency bands over parietal brain regions depending on the type of grasping. The type of object only influenced ERD patterns in the gamma band range (36-40 Hz) at parietal sites suggesting a strong relation of gamma band activity and cortical object representation. Abstract and realistic objects produced lower beta band synchronization at central sites only, whereas depending on the type of grasping an ERS in the upper alpha band (10-12 Hz) was observed. CONCLUSION: Depending on the type of the grasped object and the type of grasping stronger parietal cortical activation occurred during movement observation. SIGNIFICANCE: Discussing the results in terms of an "extended" human mirror neuron system (MNS), it could be concluded that beside sensorimotor areas a stronger involvement of parietal brain regions was found depending on the type of object and grasping movement observed.


Asunto(s)
Neuronas Espejo/fisiología , Percepción de Movimiento , Corteza Motora/fisiología , Lóbulo Parietal/fisiología , Adulto , Mapeo Encefálico , Electroencefalografía , Femenino , Humanos , Masculino , Adulto Joven
16.
J Neural Eng ; 7(2): 26007, 2010 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-20332550

RESUMEN

Brain-computer interface (BCI) systems do not work for all users. This article introduces a novel combination of tasks that could inspire BCI systems that are more accurate than conventional BCIs, especially for users who cannot attain accuracy adequate for effective communication. Subjects performed tasks typically used in two BCI approaches, namely event-related desynchronization (ERD) and steady state visual evoked potential (SSVEP), both individually and in a 'hybrid' condition that combines both tasks. Electroencephalographic (EEG) data were recorded across three conditions. Subjects imagined moving the left or right hand (ERD), focused on one of the two oscillating visual stimuli (SSVEP), and then simultaneously performed both tasks. Accuracy and subjective measures were assessed. Offline analyses suggested that half of the subjects did not produce brain patterns that could be accurately discriminated in response to at least one of the two tasks. If these subjects produced comparable EEG patterns when trying to use a BCI, these subjects would not be able to communicate effectively because the BCI would make too many errors. Results also showed that switching to a different task used in BCIs could improve accuracy in some of these users. Switching to a hybrid approach eliminated this problem completely, and subjects generally did not consider the hybrid condition more difficult. Results validate this hybrid approach and suggest that subjects who cannot use a BCI should consider switching to a different BCI approach, especially a hybrid BCI. Subjects proficient with both approaches might combine them to increase information throughput by improving accuracy, reducing selection time, and/or increasing the number of possible commands.


Asunto(s)
Atención/fisiología , Encéfalo/fisiología , Imaginación/fisiología , Actividad Motora/fisiología , Interfaz Usuario-Computador , Percepción Visual/fisiología , Adolescente , Adulto , Electroencefalografía/métodos , Potenciales Evocados Visuales , Femenino , Lateralidad Funcional , Mano/fisiología , Humanos , Masculino , Pruebas Neuropsicológicas , Periodicidad , Estimulación Luminosa , Proyectos Piloto , Procesamiento de Señales Asistido por Computador , Adulto Joven
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