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1.
Phys Rev Lett ; 129(14): 142502, 2022 Sep 30.
Artículo en Inglés | MEDLINE | ID: mdl-36240396

RESUMEN

The root mean square radii of the proton density distribution in ^{16-24}O derived from measurements of charge changing cross sections with a carbon target at ∼900A MeV together with the matter radii portray thick neutron skin for ^{22-24}O despite ^{22,24}O being doubly magic. Imprints of the shell closures at N=14 and 16 are reflected in local minima of their proton radii that provide evidence for the tensor interaction causing them. The radii agree with ab initio calculations employing the chiral NNLO_{sat} interaction, though skin thickness predictions are challenged. Shell model predictions agree well with the data.


Asunto(s)
Neutrones , Protones , Carbono
2.
Phys Rev Lett ; 124(20): 202502, 2020 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-32501052

RESUMEN

Taking benefit of the R3B/SOFIA setup to measure the mass and the nuclear charge of both fission fragments in coincidence with the total prompt-neutron multiplicity, the scission configurations are inferred along the thorium chain, from the asymmetric fission in the heavier isotopes to the symmetric fission in the neutron-deficient thorium. Against all expectations, the symmetric scission in the light thorium isotopes shows a compact configuration, which is in total contrast to what is known in the fission of the heavier thorium isotopes and heavier actinides. This new main symmetric scission mode is characterized by a significant drop in deformation energy of the fission fragments of about 19 MeV, compared to the well-known symmetric scission in the uranium-plutonium region.

3.
Phys Rev Lett ; 124(22): 222504, 2020 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-32567915

RESUMEN

We report the measurement of reaction cross sections (σ_{R}^{ex}) of ^{27,29}F with a carbon target at RIKEN. The unexpectedly large σ_{R}^{ex} and derived matter radius identify ^{29}F as the heaviest two-neutron Borromean halo to date. The halo is attributed to neutrons occupying the 2p_{3/2} orbital, thereby vanishing the shell closure associated with the neutron number N=20. The results are explained by state-of-the-art shell model calculations. Coupled-cluster computations based on effective field theories of the strong nuclear force describe the matter radius of ^{27}F but are challenged for ^{29}F.

4.
Phys Rev Lett ; 123(9): 092502, 2019 Aug 30.
Artículo en Inglés | MEDLINE | ID: mdl-31524489

RESUMEN

The most remote isotope from the proton dripline (by 4 atomic mass units) has been observed: ^{31}K. It is unbound with respect to three-proton (3p) emission, and its decays have been detected in flight by measuring the trajectories of all decay products using microstrip detectors. The 3p emission processes have been studied by the means of angular correlations of ^{28}S+3p and the respective decay vertices. The energies of the previously unknown ground and excited states of ^{31}K have been determined. This provides its 3p separation energy value S_{3p} of -4.6(2) MeV. Upper half-life limits of 10 ps of the observed ^{31}K states have been derived from distributions of the measured decay vertices.

5.
Comput Intell Neurosci ; 2018: 5276161, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29606959

RESUMEN

Background and Objective. Needle electromyography can be used to detect the number of changes and morphological changes in motor unit potentials of patients with axonal neuropathy. General mathematical methods of pattern recognition and signal analysis were applied to recognize neuropathic changes. This study validates the possibility of extending and refining turns-amplitude analysis using permutation entropy and signal energy. Methods. In this study, we examined needle electromyography in 40 neuropathic individuals and 40 controls. The number of turns, amplitude between turns, signal energy, and "permutation entropy" were used as features for support vector machine classification. Results. The obtained results proved the superior classification performance of the combinations of all of the above-mentioned features compared to the combinations of fewer features. The lowest accuracy from the tested combinations of features had peak-ratio analysis. Conclusion. Using the combination of permutation entropy with signal energy, number of turns and mean amplitude in SVM classification can be used to refine the diagnosis of polyneuropathies examined by needle electromyography.


Asunto(s)
Algoritmos , Electromiografía , Enfermedades del Sistema Nervioso Periférico/fisiopatología , Procesamiento de Señales Asistido por Computador , Máquina de Vectores de Soporte , Adulto , Anciano , Entropía , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven
6.
Phys Rev Lett ; 117(20): 202501, 2016 Nov 11.
Artículo en Inglés | MEDLINE | ID: mdl-27886506

RESUMEN

Excitation spectra of ^{11}C are measured in the ^{12}C(p,d) reaction near the η^{'} emission threshold. A proton beam extracted from the synchrotron SIS-18 at GSI with an incident energy of 2.5 GeV impinges on a carbon target. The momenta of deuterons emitted at 0° are precisely measured with the fragment separator (FRS) operated as a spectrometer. In contrast to theoretical predictions on the possible existence of deeply bound η^{'}-mesic states in carbon nuclei, no distinct structures are observed associated with the formation of bound states. The spectra are analyzed to set stringent constraints on the formation cross section and on the hitherto barely known η^{'}-nucleus interaction.

7.
Phys Rev Lett ; 117(10): 102501, 2016 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-27636470

RESUMEN

Proton radii of ^{12-19}C densities derived from first accurate charge changing cross section measurements at 900A MeV with a carbon target are reported. A thick neutron surface evolves from ∼0.5 fm in ^{15}C to ∼1 fm in ^{19}C. The halo radius in ^{19}C is found to be 6.4±0.7 fm as large as ^{11}Li. Ab initio calculations based on chiral nucleon-nucleon and three-nucleon forces reproduce the radii well.

8.
Phys Rev Lett ; 117(1): 012501, 2016 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-27419564

RESUMEN

The ß-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with ß-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb, and Bi in the mass region N≳126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the ß-decay strength distribution. This provides important constraints on global theoretical models currently used in r-process nucleosynthesis.

9.
Phys Rev Lett ; 115(20): 202501, 2015 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-26613434

RESUMEN

Previously unknown isotopes (30)Ar and (29)Cl have been identified by measurement of the trajectories of their in-flight decay products (28)S+p+p and (28)S+p, respectively. The analysis of angular correlations of the fragments provided information on decay energies and the structure of the parent states. The ground states of (30)Ar and (29)Cl were found at 2.25(-0.10)(+0.15) and 1.8±0.1 MeV above the two- and one-proton thresholds, respectively. The lowest states in (30)Ar and (29)Cl point to a violation of isobaric symmetry in the structure of these unbound nuclei. The two-proton decay has been identified in a transition region between simultaneous two-proton and sequential proton emissions from the (30)Ar ground state, which is characterized by an interplay of three-body and two-body decay mechanisms. The first hint of a fine structure of the two-proton decay of (30)Ar*(2(+)) has been obtained by detecting two decay branches into the ground and first-excited states of the (28)S fragment.

11.
Phys Rev Lett ; 113(13): 132501, 2014 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-25302882

RESUMEN

The first determination of radii of point proton distribution (proton radii) of (12-17)B from charge-changing cross sections (σ(CC)) measurements at the FRS, GSI, Darmstadt is reported. The proton radii are deduced from a finite-range Glauber model analysis of the σ(CC). The radii show an increase from ¹³B to ¹7B and are consistent with predictions from the antisymmetrized molecular dynamics model for the neutron-rich nuclei. The measurements show the existence of a thick neutron surface with neutron-proton radius difference of 0.51(0.11) fm in ¹7B.

12.
Spinal Cord ; 52(9): 652-7, 2014 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-24891012

RESUMEN

OBJECTIVE: To develop an International Spinal Cord Injury (SCI) Upper Extremity Basic Data Set as part of the International SCI Data Sets, which facilitates consistent collection and reporting of basic upper extremity findings in the SCI population. SETTING: International. METHODS: A first draft of a SCI Upper Extremity Data Set was developed by an international working group. This was reviewed by many different organisations, societies and individuals over several months. A final version was created. VARIABLES: The final version of the International SCI Upper Extremity Data Set contains variables related to basic hand-upper extremity function, use of assistive devices, SCI-related complications to upper extremity function and upper extremity/hand reconstructive surgery. Instructions for data collection and the data collection form are freely available on the ISCoS website (www.iscos.org.uk). CONCLUSION: The International SCI Upper Extremity Basic Data Set will facilitate consistent collection and reporting of basic upper extremity findings in the SCI population.


Asunto(s)
Bases de Datos Factuales , Cooperación Internacional , Traumatismos de la Médula Espinal/complicaciones , Traumatismos de la Médula Espinal/fisiopatología , Extremidad Superior/fisiopatología , Recolección de Datos , Humanos
13.
Acta Neurochir (Wien) ; 156(7): 1335-9, 2014 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-24691974

RESUMEN

BACKGROUND: Studies have shown slow healing of peripheral nerve injury in elderly patients. Carpal tunnel syndrome (CTS) is the most frequent compressive mononeuropathy, affecting mostly older people and females. Few studies have assessed electrophysiological differences between younger and older patients. We aimed to evaluate age-dependent differences in electrophysiological parameters preoperatively and postoperatively over a 100-day postoperative period. METHOD: This retrospective study included 258 hands of patients who underwent conventional open-technique carpal tunnel syndrome surgery. Patients with paresthesia in the median nerve distribution or with impaired sensation or abnormal findings in sensory and motor median nerve conduction studies were enrolled. The age dependence of the preoperative values of distal motor latency, amplitude of the compound motor action potential and sensory conduction velocity was estimated using regression analysis. RESULTS: Statistically significant age dependence was found for the preoperative distal motor latency, compound motor action potential, amplitude and sensory conduction velocity. The repair of segmental demyelination was nearly twice as slow in the older group, at a 5 % significance level, even when comparing groups with the same preoperative distal motor latency. CONCLUSIONS: Analysis of preoperative nerve conduction parameters indicates that surgery for carpal tunnel syndrome is performed later in older patients.


Asunto(s)
Envejecimiento , Síndrome del Túnel Carpiano/fisiopatología , Síndrome del Túnel Carpiano/cirugía , Recuperación de la Función , Adulto , Anciano , Anciano de 80 o más Años , Potenciales Evocados Motores , Femenino , Humanos , Masculino , Nervio Mediano/fisiopatología , Persona de Mediana Edad , Conducción Nerviosa/fisiología , Examen Neurológico , Parestesia/etiología , Estudios Retrospectivos , Trastornos de la Sensación/etiología , Trastornos de la Sensación/fisiopatología
14.
Phys Rev Lett ; 110(17): 172501, 2013 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-23679711

RESUMEN

A measurement of the reduced transition probability for the excitation of the ground state to the first 2+ state in 104Sn has been performed using relativistic Coulomb excitation at GSI. 104Sn is the lightest isotope in the Sn chain for which this quantity has been measured. The result is a key point in the discussion of the evolution of nuclear structure in the proximity of the doubly magic nucleus 100Sn. The value B(E2; 0+ → 2+) = 0.10(4) e2b2 is significantly lower than earlier results for 106Sn and heavier isotopes. The result is well reproduced by shell model predictions and therefore indicates a robust N = Z = 50 shell closure.

15.
Dentomaxillofac Radiol ; 42(7): 20120391, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23640989

RESUMEN

The purpose of this study is (1) to introduce a new approach for edge detection in orthopantograms (OPGs) and an improved automatic parameter selector for common edge detectors, (2) to present a comparison between our novel approach with common edge detectors and (3) to provide faster outputs without compromising quality. A new approach for edge detection based on statistical measures was introduced: (1) a set of N edge detection results is calculated from a given input image and a selected type of edge detector, (2) N correspondence maps are constructed from N edge detection results, (3) probabilities and average probabilities are computed, (4) an overall correspondence is evaluated for each correspondence map and (5) the correspondence map providing the best overall correspondence is taken as the result of edge detection procedure. A comparison with common edge detectors (the Roberts, Prewitt, Sobel, Laplacian of the Gaussian and Canny methods) with various parameter settings (304 combinations for each test image) was carried out. The methods were assessed objectively [edge mismatch error (EME), modified Hausdorff distance (MHD) and principal component analysis] and subjectively by experts in dentistry and based on time demands. The suitability of the new approach for edge detection in OPGs was confirmed by experts. The current conventional methods in edge detection in OPGs are inadequate (none of the tested methods reach an EME value or MHD value below 0.1). Our proposed approach for edge detection shows promising potential for its implementation in clinical dentistry. It enhances the accuracy of OPG interpretation and advances diagnosis and treatment planning.


Asunto(s)
Interpretación de Imagen Radiográfica Asistida por Computador/métodos , Radiografía Panorámica/estadística & datos numéricos , Algoritmos , Puntos Anatómicos de Referencia/diagnóstico por imagen , Artefactos , Caries Dental/diagnóstico por imagen , Humanos , Procesamiento de Imagen Asistido por Computador/estadística & datos numéricos , Quistes Maxilomandibulares/diagnóstico por imagen , Distribución Normal , Análisis de Componente Principal , Probabilidad , Factores de Tiempo , Extracción Dental , Diente Supernumerario/diagnóstico por imagen
16.
Phys Rev Lett ; 107(17): 172502, 2011 Oct 21.
Artículo en Inglés | MEDLINE | ID: mdl-22107511

RESUMEN

A ß-decaying high-spin isomer in (96)Cd, with a half-life T(1/2)=0.29(-0.10)(+0.11) s, has been established in a stopped beam rare isotope spectroscopic investigations at GSI (RISING) experiment. The nuclei were produced using the fragmentation of a primary beam of (124)Xe on a (9)Be target. From the half-life and the observed γ decays in the daughter nucleus, (96)Ag, we conclude that the ß-decaying state is the long predicted 16(+) "spin-gap" isomer. Shell-model calculations, using the Gross-Frenkel interaction and the πν(p(1/2),g(9/2)) model space, show that the isoscalar component of the neutron-proton interaction is essential to explain the origin of the isomer. Core excitations across the N=Z=50 gaps and the Gamow-Teller strength, B(GT) distributions have been studied via large-scale shell-model calculations using the πν(g,d,s) model space to compare with the experimental B(GT) value obtained from the half-life of the isomer.

17.
J Neural Eng ; 8(4): 046019, 2011 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-21701057

RESUMEN

Functional electrical stimulation (FES) is used to improve motor function after injury to the central nervous system. Some FES systems use artificial sensors to switch between finite control states. To optimize FES control of the complex behavior of the musculo-skeletal system in activities of daily life, it is highly desirable to implement feedback control. In theory, sensory neural signals could provide the required control signals. Recent studies have demonstrated the feasibility of deriving limb-state estimates from the firing rates of primary afferent neurons recorded in dorsal root ganglia (DRG). These studies used multiple linear regression (MLR) methods to generate estimates of limb position and velocity based on a weighted sum of firing rates in an ensemble of simultaneously recorded DRG neurons. The aim of this study was to test whether the use of a neuro-fuzzy (NF) algorithm (the generalized dynamic fuzzy neural networks (GD-FNN)) could improve the performance, robustness and ability to generalize from training to test sets compared to the MLR technique. NF and MLR decoding methods were applied to ensemble DRG recordings obtained during passive and active limb movements in anesthetized and freely moving cats. The GD-FNN model provided more accurate estimates of limb state and generalized better to novel movement patterns. Future efforts will focus on implementing these neural recording and decoding methods in real time to provide closed-loop control of FES using the information extracted from sensory neurons.


Asunto(s)
Estimulación Eléctrica/métodos , Lógica Difusa , Ganglios Espinales/fisiología , Neuronas/fisiología , Sensación/fisiología , Algoritmos , Anestesia , Animales , Inteligencia Artificial , Fenómenos Biomecánicos , Gatos , Estimulación Eléctrica/instrumentación , Procesamiento Automatizado de Datos , Extremidades/fisiología , Ganglios Espinales/citología , Miembro Posterior/inervación , Miembro Posterior/fisiología , Articulaciones/fisiología , Modelos Lineales , Modelos Neurológicos , Movimiento/fisiología , Redes Neurales de la Computación
18.
Osteoporos Int ; 22(1): 305-15, 2011 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-20358362

RESUMEN

UNLABELLED: We applied regression techniques to a large cohort of patients to understand why certain patients are prescribed medications to prevent glucocorticoid-induced osteoporosis (GIO). Rates of prescriptions to prevent osteoporosis were low. The presence of drugs and disorders associated with osteoporosis and gastrointestinal conditions actually are associated with a decreased likelihood of receiving osteoporosis-preventing medications. INTRODUCTION: To understand why some patients are prescribed medications to prevent GIO while other patients are not, we examined whether there is an association among osteoporosis-inducing medical conditions or medications and prescriptions for osteoporosis prophylaxis in a large cohort of rheumatoid arthritis patients on chronic glucocorticoids. METHODS: Department of Veterans' Affairs national administrative databases were used to construct a cohort (n = 9,605) and provide the data for this study. Multivariate logistic regression was performed to determine medical conditions and medications associated with dispensing of GIO-preventive medications, controlling for sociodemographic variables, comorbidities, glucocorticoid dosage, prior fractures, and rheumatoid arthritis severity. A subanalysis examined predictors of early GIO prevention. RESULTS: Subjects were more likely to receive GIO prophylaxis if they were older, African American, treated with multiple antirheumatic disease-modifying drugs, or received greater glucocorticoid exposure. The prescription of certain drug classes (loop diuretics and anticonvulsants) and conditions (malignancy, renal insufficiency, alcohol abuse, and hepatic disease) were associated with lower likelihood of GIO prophylaxis, despite putative links between these agents/conditions and osteoporosis. The presence of gastrointestinal disorders dramatically decreased likelihood of GIO prophylaxis. Few characteristics predicted the dispensing of GIO-preventing medications within 7 days of the initial glucocorticoid start date. CONCLUSIONS: Rates of prescriptions to prevent osteoporosis in a cohort of older men with rheumatoid arthritis on chronic glucocorticoids were low. Gastrointestinal disorders and drugs and disorders potentially linked to osteoporosis are associated with diminished odds of being prescribed GIO-preventing medications.


Asunto(s)
Artritis Reumatoide/tratamiento farmacológico , Conservadores de la Densidad Ósea/administración & dosificación , Glucocorticoides/efectos adversos , Osteoporosis/prevención & control , Anciano , Conservadores de la Densidad Ósea/uso terapéutico , Estudios de Cohortes , Esquema de Medicación , Prescripciones de Medicamentos/estadística & datos numéricos , Utilización de Medicamentos/estadística & datos numéricos , Glucocorticoides/administración & dosificación , Glucocorticoides/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Osteoporosis/inducido químicamente , Selección de Paciente , Factores de Riesgo
19.
Brain Res Bull ; 84(4-5): 343-57, 2011 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-20728509

RESUMEN

The ability to detect physiological changes associated with treatments to effect axonal regeneration, or novel rehabilitation strategies, for spinal cord injury will be challenging using the widely employed American Spinal Injuries Association (ASIA) impairment scales (AIS) for sensory and motor function. Despite many revisions to the AIS standard neurological assessment, there remains a perceived need for more sensitive, quantitative and objective outcome measures. The purpose of Stage 1 of the Clinical Initiative was to develop these tools and then, in Stage 2 to test them for reliability against natural recovery and treatments expected to produce functional improvements in those with complete or incomplete spinal cord injury (SCI). Here we review aspects of the progress made by four teams involved in Stage 2. The strategies employed by the individual teams were (1) application of repetitive transcranial magnetic stimulation (rTMS) to the motor cortex in stable (chronic) SCI with intent to induce functional improvement of upper limb function, (2) a tele-rehabilitation approach using functional electrical stimulation to provide hand opening and grip allowing incomplete SCI subjects to deploy an instrumented manipulandum for hand and arm exercises and to play computer games, (3) weight-assisted treadmill walking therapy (WAT) comparing outcomes in acute and chronic groups of incomplete SCI patients receiving robotic assisted treadmill therapy, and (4) longitudinal monitoring of the natural progress of recovery in incomplete SCI subjects using motor tests for the lower extremity to investigate strength and coordination.


Asunto(s)
Recuperación de la Función/fisiología , Traumatismos de la Médula Espinal/fisiopatología , Traumatismos de la Médula Espinal/rehabilitación , Traumatismos de la Médula Espinal/terapia , Resultado del Tratamiento , Potenciales Evocados Motores/fisiología , Ejercicio Físico , Humanos , Regeneración Nerviosa/fisiología , Examen Neurológico , Telemedicina
20.
Artículo en Inglés | MEDLINE | ID: mdl-22256032

RESUMEN

With the advent of new approaches to upper extremity recovery after stroke and spinal cord injury, the quantitative evaluation of hand function has become a crucial component of outcome evaluation. Recently we developed a workstation, the ReJoyce (Rehabilitation Joystick for Computer Exercise) on which subjects perform a variety of movement tasks while playing computer games. An important feature of the system is the ReJoyce Automated Hand Function Test (RAHFT). In this study we compared and validated the RAHFT against two widely-used clinical tests, the Action Research Arm Test (ARAT) [1][2] and the Fugl-Meyer Assessment (FMA) [3]. All three tests were performed in 34 separate sessions in 13 tetraplegic individuals. Principal component and regression analyses revealed that both the ARAT and the RAHFT correlated well with the first principle component fitted to the scores of the three tests. The FMA was less well correlated. These data help validate the RAHFT as a quantitative, automated alternative to the ARAT and FMA. The RAHFT is the first comprehensive test of hand function that does not depend on human judgment.


Asunto(s)
Rehabilitación de Accidente Cerebrovascular , Extremidad Superior/fisiología , Automatización , Diseño de Equipo , Mano/fisiología , Humanos , Sistemas Hombre-Máquina , Actividad Motora/fisiología , Movimiento/fisiología , Análisis de Componente Principal , Cuadriplejía/fisiopatología , Recuperación de la Función/fisiología , Análisis de Regresión , Reproducibilidad de los Resultados , Interfaz Usuario-Computador
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