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1.
Phys Rev E ; 108(2-1): 024208, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37723764

RESUMO

The out-of-time order correlator (OTOC) has been widely studied in closed quantum systems. However, there are very few studies for open systems and they are mainly focused on isolating the effects of scrambling from those of decoherence. Adopting a different point of view, we study the interplay between these two processes. This proves crucial in order to explain the OTOC behavior when a phase space contracting dissipation is present, ubiquitous not only in real life quantum devices but in the dynamical systems area. The OTOC decay rate is closely related to the classical Lyapunov exponent-with some differences-and more sensitive in order to distinguish the chaotic from the regular behavior than other measures. On the other hand, it is revealed as a generally simple function of the longest lived eigenvalues of the quantum evolution operator. We find no simple connection with the Ruelle-Pollicott resonances, but by adding Gaussian noise of ℏ_{eff} size to the classical system we recover the OTOC decay rate, which is a consequence of the correspondence principle put forward in Phys. Rev. Lett. 108, 210605 (2012)10.1103/PhysRevLett.108.210605 and Phys. Rev. E 99, 042214 (2019)10.1103/PhysRevE.99.042214.

2.
Int J Numer Method Biomed Eng ; 38(4): e3577, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35094497

RESUMO

Radioembolization (RE) is a medical treatment for primary and secondary liver cancer that involves the transcatheter intraarterial delivery of micron-sized and radiation-emitting microspheres, with the goal of improving microsphere deposition in the tumoral bed while sparing healthy tissue. An increasing number of in vitro and in silico studies on RE in the literature suggest that the particle injection velocity, spatial location of the catheter tip and catheter type are important parameters in particle distribution. The present in silico study assesses the performance of a novel catheter design that promotes particle dispersion near the injection point, with the goal of generating a particle distribution that mimics the flow split to facilitate tumour targeting. The design is based on two factors: the direction and the velocity at which particles are released from the catheter. A series of simulations was performed with the catheter inserted at an idealised hepatic artery tree with physiologically realistic boundary conditions. Two longitudinal microcatheter positions in the first generation of the tree were studied by analysing the performance of the catheter in terms of the outlet-to-outlet particle distribution and split flow matching. The results show that the catheter with the best performance is one with side holes on the catheter wall and a closed frontal tip. This catheter promotes a flow-split-matching particle distribution, which improves as the injection crossflow increases.


Assuntos
Hemodinâmica , Neoplasias Hepáticas , Catéteres , Hemodinâmica/fisiologia , Artéria Hepática/fisiologia , Humanos , Neoplasias Hepáticas/irrigação sanguínea , Neoplasias Hepáticas/radioterapia
3.
Phys Rev E ; 102(5-1): 052133, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33327203

RESUMO

The out-of-time-order correlator (OTOC) has recently become relevant in different areas where it has been linked to scrambling of quantum information and entanglement. It has also been proposed as a good indicator of quantum complexity. In this sense, the OTOC-RE theorem relates the OTOCs summed over a complete basis of operators to the second Renyi entropy. Here we have studied the OTOC-RE correspondence on physically meaningful bases like the ones constructed with the Pauli, reflection, and translation operators. The evolution is given by a paradigmatic bi-partite system consisting of two perturbed and coupled Arnold cat maps with different dynamics. We show that the sum over a small set of relevant operators is enough in order to obtain a very good approximation for the entropy and, hence, to reveal the character of the dynamics. In turn, this provides us with an alternative natural indicator of complexity, i.e., the scaling of the number of relevant operators with time. When represented in phase space, each one of these sets reveals the classical dynamical footprints with different depth according to the chosen basis.

4.
Int J Numer Method Biomed Eng ; 36(6): e3337, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32212316

RESUMO

In the last decades, the numerical studies on hemodynamics have become a valuable explorative scientific tool. The very first studies were done over idealized geometries, but as numerical methods and the power of computers have become more affordable, the studies tend to be patient specific. We apply the study to the numerical analysis of tumor-targeting during liver radioembolization (RE). RE is a treatment for liver cancer, and is performed by injecting radiolabeled microspheres via a catheter placed in the hepatic artery. The objective of the procedure is to maximize the release of radiolabeled microspheres into the tumor and avoid a healthy tissue damage. Idealized virtual arteries can serve as a generalist approach that permits to separately analyze the effect of a variable in the microsphere distribution with respect to others. However, it is important to use proper physiological boundary conditions (BCs). It is not obvious, the need to account for the effect of tortuosity when using an idealized virtual artery. We study the use of idealized geometry of a hepatic artery as a valid research tool, exploring the importance of using realistic spiral-flow inflow BC. By using a literature-based cancer scenario, we vary two parameters to analyze the microsphere distribution through the outlets of the geometry. The parameters varied are the type of microspheres injected and the microsphere injection velocity. The results with realistic inlet velocity profile showed that the particle distribution in the liver segments is not affected by the analyzed injection velocity values neither by the particle density. NOVELTY STATEMENT: In this article, we assessed the use of idealized geometries as a valid research tool and applied the use of an idealized geometry to the case of an idealized hepatic artery to study the particle-hemodynamics during radioembolization (RE). We studied three different inflow boundary conditions (BCs) to assess the usefulness of the geometry, two types of particle injection velocities and two types of commercially available microspheres for RE treatment. In recent years, the advent in computational resources allowed for more detailed patient-specific geometry generation and discretization and hemodynamics simulations. However, general studies based on idealized geometries can be performed in order to provide medical doctors with some basic and general guidelines when using a given catheter for a given cancer scenario. Moreover, using an idealized geometry can be a reasonable approach which allows us to isolate a given parameter and control other parameters, so that parameters can be independently assessed. Even though an idealized geometry does not match any patient's geometry, the use of an idealized geometry can be valid when drawing general conclusions that may be useful in patient-specific cases. However, we believe that even if an idealized hepatic artery geometry is used for the study, it is necessary to account for the upstream and downstream tortuosity of vessels through the BCs. In this work, we highlighted the need of modeling the tortuosity of upstream and downstream vasculatures through the BCs.


Assuntos
Artéria Hepática/fisiologia , Microesferas , Hemodinâmica/fisiologia , Humanos , Fígado/metabolismo , Fígado/fisiologia
5.
Phys Rev E ; 99(4-1): 042214, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31108630

RESUMO

By means of studying the evolution equation for the Wigner distributions of quantum dissipative systems we derive the quantum corrections to the classical Liouville dynamics, taking into account the standard quantum friction model. The resulting evolution turns out to be the classical one plus fluctuations that depend not only on the ℏ size but also on the momentum and the dissipation parameter (i.e., the coupling with the environment). On the other hand, we extend our studies of a paradigmatic system based on the kicked rotator, and we confirm that by adding fluctuations only depending on the size of the Planck constant we essentially recover the quantum behavior. This is systematically measured in the parameter space with the overlaps and differences in the dispersion of the marginal distributions corresponding to the Wigner functions. Taking into account these results and analyzing the Wigner evolution equation we conjecture that the chaotic nature of our system is responsible for the independence on the momentum, while the dependence on the dissipation is provided implicitly by the dynamics.

6.
Phys Rev E ; 99(1-1): 012214, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30780255

RESUMO

We study the properties of classical and quantum stable structures in a three-dimensional (3D) parameter space corresponding to the dissipative kicked top. This is a model system in quantum and classical chaos that gives a starting point for many body examples. We are able to identify the influence of these structures in the spectra and eigenstates of the corresponding (super)operators. This provides a complementary view with respect to the typical two-dimensional parameter space systems found in the literature. Many properties of the eigenstates, like its localization behavior, can be generalized to this higher-dimensional parameter space and spherical phase space topology. Moreover, we find a 3D phenomenon-generalizable to more dimensions-that we call the coalescence-separation of (q)ISSs, whose main consequence is a marked enhancement of quantum localization. This could be of relevance for systems that have attracted a lot of attention very recently.

7.
Rev. cuba. estomatol ; 54(3): 0-0, jul.-set. 2017. ilus, tab
Artigo em Espanhol | LILACS | ID: biblio-901044

RESUMO

Introducción: la tomografía computarizada de haz cónico en odontología es de reciente introducción en Chile y no existe información acerca de su uso en poblaciones jóvenes. Desde el punto de vista de la protección radiológica, su uso es de especial preocupación en estos grupos, debido a su mayor susceptibilidad a las radiaciones ionizantes. Objetivos: determinar las indicaciones y parámetros de exposición de la tomografía computarizada de haz cónico en menores de 25 años atendidos en un periodo de 12 meses en un centro privado de radiología maxilofacial de Talca, Chile. Métodos: estudio observacional descriptivo de corte transversal. Se recolectaron datos de 240 exámenes. Se registraron los parámetros de exposición usados por un equipo SkyView (MyRay, Imola, Italia) y las indicaciones clínicas para cada examen. El procesamiento de los datos se realizó mediante estadística descriptiva, y se utilizó la prueba de Fisher. Resultados: la principal indicación fue localización de piezas dentarias (46 por ciento), seguido por planificación de exodoncia de terceros molares (25 por ciento), planificación de implantes (7,1 por ciento) y articulación temporomandibular (6 por ciento). En todos los grupos etarios el campo de visión pequeño fue el más usado (81 por ciento). El producto miliamperaje-tiempo fue 100,7 mAs en pre-escolares/niños, y 110,1-110,9 mAs en adolescentes y adultos jóvenes. La dosis efectiva fue 52,4 µSv en pre-escolares/niños y 62,1 µSv en adolescentes y adultos jóvenes. El 100 por ciento de los exámenes usó rotación parcial. El 96 porciento de las indicaciones concordó con lo señalado por las Guías Nº172 de la Comisión Europea. Conclusiones: las principales indicaciones en orden decreciente fueron localización de piezas dentarias, planificación de exodoncia de terceros molares, planificación de implantes y articulación temporomandibular. El campo de visión pequeño fue el más usado. La rotación total se encontró en todos los casos. No se encontró diferencias significativas en el uso del producto miliamperaje-tiempo y dosis efectiva entre los distintos grupos estudiados(AU)


Introduction: dental cone-beam computed tomography is a technology of recent introduction in Chile and there is no information regarding its use in young populations. From the point of view of radiation protection, its use with young patients is particularly worrisome, due to their greater susceptibility to ionizing radiation. Objective: determine the indications and exposure parameters of cone-beam computed tomography in patients under 25 years of age cared for in a 12-month period at a private maxillofacial radiology center in Talca, Chile. Methods: a observational descriptive cross-sectional study was conducted. Data were collected from 240 examinations. The exposure parameters used by a SkyView set (MyRay, Imola, Italy) were recorded, and note was taken of the clinical indications for each test. Data were processed by descriptive statistics using Fisher's test. Results: the main indication was tooth location (46 percent), followed by planning of third molar extraction (25 percent), implant planning (7.1 percent) and temporomandibular joint (6 percent). The small field of view was the most commonly used in all age groups (81 percent). The milliampere-time product was 100.7 mAs for preschool children and 110.1-110.9 mAs for adolescents and young adults. The effective dose was 52.4 µSv for preschool children and 62.1 µSv for adolescents and young adults. Partial rotation was used in 100 percent of the tests. 96 percent of the indications complied with Guideline No 172 of the European Commission. Conclusions: the main indications were tooth location, planning of third molar extraction, implant planning and temporomandibular joint, in that order. The small field of view was the most commonly used. Total rotation was found in all cases. Milliampere-time product and effective dose did not show any significant differences between the age groups studied(AU)


Assuntos
Humanos , Pré-Escolar , Criança , Adolescente , Adulto , Tomografia Computadorizada de Feixe Cônico/estatística & dados numéricos , Coleta de Dados/métodos , Dosagem Radioterapêutica , Estudos Transversais , Epidemiologia Descritiva , Estudo Observacional
8.
Phys Rev E ; 95(6-1): 062202, 2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-28709295

RESUMO

In the context of dissipative systems, we show that for any quantum chaotic attractor a corresponding classical chaotic attractor can always be found. We provide a general way to locate them, rooted in the structure of the parameter space (which is typically bidimensional, accounting for the forcing strength and dissipation parameters). In cases where an approximate pointlike quantum distribution is found, it can be associated with exceptionally large regular structures. Moreover, supposedly anomalous quantum chaotic behavior can be very well reproduced by the classical dynamics plus Gaussian noise of the size of an effective Planck constant ℏ_{eff}. We give support to our conjectures by means of two paradigmatic examples of quantum chaos and transport theory. In particular, a dissipative driven system becomes fundamental in order to extend their validity to generic cases.

9.
Otol Neurotol ; 38(3): 408-415, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28192382

RESUMO

OBJECTIVE: To investigate the efficacy and safety of endoscopic middle ear paraganglioma (glomus tympanicum) resection. STUDY DESIGN: Case series with chart review. SETTING: Multi-institutional tertiary university medical centers. PATIENTS: Adult patients with middle ear paragangliomas treated via a transcanal endoscopic approach from 1/2012 to 11/2015. INTERVENTION: All tumors were initially approached via a transcanal endoscopic technique. An operating microscope was used only if the tumor could not be adequately visualized or resected with endoscopic techniques alone. MAIN OUTCOME MEASURES: The main outcome was completeness of tumor resection via the endoscopic technique. Secondary measures were resolution of pulsatile tinnitus, audiometric outcomes, surgical duration, and surgical complications. RESULTS: Endoscopic resection was attempted on 14 middle ear paragangliomas. Thirteen patients (93%) were women with a mean age of 61.6 years. The mean tumor size was 6.2 mm (SD, 3.3). Eleven cases (79%) had complete resection via an exclusive endoscopic approach. The mean surgical duration was 108.1 minutes (SD, 55.6). One case required use of an operating microscope via a transcanal route and two cases required postauricular incisions with mastoidectomy. There were no significant postoperative complications. Two patients (14%) had tympanic membrane perforations repaired intraoperatively without residual perforation on follow-up. All patients had normal postoperative facial nerve function. Pulsatile tinnitus resolved after surgery in all 13 patients who presented with this symptom preoperatively. The mean pure-tone average improved by 5.9 dB (SD, 4.6) after surgery. CONCLUSIONS: Endoscopic management of middle ear paraganglioma is safe, feasible, and effective.


Assuntos
Neoplasias da Orelha/cirurgia , Tumor de Glomo Timpânico/cirurgia , Cirurgia Endoscópica por Orifício Natural/métodos , Adolescente , Adulto , Idoso , Audiometria , Neoplasias da Orelha/patologia , Orelha Média/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento , Adulto Jovem
10.
Phys Rev E ; 96(3-1): 032202, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29346928

RESUMO

By analyzing a paradigmatic example of the theory of dissipative systems-the classical and quantum dissipative standard map-we are able to explain the main features of the decay to the quantum equilibrium state. The classical isoperiodic stable structures typically present in the parameter space of these kinds of systems play a fundamental role. In fact, we have found that the period of stable structures that are near in this space determines the phase of the leading eigenstates of the corresponding quantum superoperator. Moreover, the eigenvectors show a strong localization on the corresponding periodic orbits (limit cycles). We show that this sort of scarring phenomenon (an established property of Hamiltonian and projectively open systems) is present in the dissipative case and it is of extreme simplicity.

11.
Phys Rev E ; 96(6-1): 062144, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29347316

RESUMO

We study a generic and paradigmatic two-degrees-of-freedom system consisting of two coupled perturbed cat maps with different types of dynamics. The Wigner separability entropy (WSE)-equivalent to the operator space entanglement entropy-and the classical separability entropy (CSE) are used as measures of complexity. For the case where both degrees of freedom are hyperbolic, the maps are classically ergodic and the WSE and the CSE behave similarly, growing to higher values than in the doubly elliptic case. However, when one map is elliptic and the other hyperbolic, the WSE reaches the same asymptotic value than that of the doubly hyperbolic case but at a much slower rate. The CSE only follows the WSE for a few map steps, revealing that classical dynamical features are not enough to explain complexity growth.

12.
Phys Rev E ; 93: 042133, 2016 04.
Artigo em Inglês | MEDLINE | ID: mdl-27176280

RESUMO

We systematically study several classical-quantum correspondence properties of the dissipative modified kicked rotator, a paradigmatic ratchet model. We explore the behavior of the asymptotic currents for finite ℏ_{eff} values in a wide range of the parameter space. We find that the correspondence between the classical currents with thermal noise providing fluctuations of size ℏ_{eff} and the quantum ones without it is very good in general with the exception of specific regions. We systematically consider the spectra of the corresponding classical Perron-Frobenius operators and quantum superoperators. By means of an average distance between the classical and quantum sets of eigenvalues we find that the correspondence is unexpectedly quite uniform. This apparent contradiction is solved with the help of the Weyl-Wigner distributions of the equilibrium eigenvectors, which reveal the key role of quantum effects by showing surviving coherences in the asymptotic states.

13.
Otolaryngol Head Neck Surg ; 154(6): 1093-8, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-27006295

RESUMO

OBJECTIVES: To investigate intra- and postoperative outcomes of endoscopic stapes surgery. STUDY DESIGN: Case series with chart review. SETTING: Four tertiary care otologic centers. SUBJECTS AND METHODS: Sixty-five subjects 18 years and older who underwent endoscopic stapes surgeries were analyzed. Variables analyzed included surgical techniques and intraoperative findings. Outcomes measured included postoperative hearing and complications to date. RESULTS: Fifty-one patients met inclusion and exclusion criteria. The average patient age was 48.1 years (range, 26-87 years), with 60.0% female patients. Patients had a median follow-up of 5.13 months (range, 0.8-57.4 months). Of the subjects, 71.7% required scutum removal. The chorda tympani nerve was manipulated in 94.0% of subjects and transected in 12.0%. At last follow-up visit, the median air-bone gap decreased from 34.5 dB hearing level (HL) preoperatively to 9.0 dB HL postoperatively (P < .0001). Ninety percent of subjects had closure of their air-bone gap ≤20 dB HL. Intraoperative complications included tympanic membrane tears in 8.0% of subjects, all of which resolved at first follow-up. Postoperatively, 10.0% of subjects complained of altered taste. CONCLUSIONS: The present multicentered study of endoscopic stapes surgery demonstrates similar audiometric and postoperative outcomes previously published in the literature, with a median postoperative air-bone gap of 9.0 dB HL. Future prospective endoscopic stapes surgery studies, addressing the need for scutum removal, postoperative taste changes, and pain scores, are merited.


Assuntos
Endoscopia/métodos , Cirurgia do Estribo/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Audiometria , Brasil , Colômbia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Complicações Pós-Operatórias , Estudos Retrospectivos , Resultado do Tratamento , Estados Unidos
14.
Artigo em Inglês | MEDLINE | ID: mdl-26651762

RESUMO

We compare the quantum and classical properties of the (quantum) isoperiodic stable structures [(Q)ISSs], which organize the parameter space of a paradigmatic dissipative ratchet model, i.e., the dissipative modified kicked rotator. We study the spectral behavior of the corresponding classical Perron-Frobenius operators with thermal noise and the quantum superoperators without it for small ℏ(eff) values. We find a remarkable similarity between the classical and quantum spectra. This finding significantly extends previous results-obtained for the mean currents and asymptotic distributions only-and, on the other hand, unveils a classical to quantum correspondence mechanism where the classical noise is qualitatively different from the quantum one. This is crucial not only for simple attractors but also for chaotic ones, where just analyzing the asymptotic distribution is revealed as insufficient. Moreover, we provide with a detailed characterization of relevant eigenvectors by means of the corresponding Weyl-Wigner distributions, in order to better identify similarities and differences. Finally, this model being generic, it allows us to conjecture that this classical to quantum correspondence mechanism is a universal feature of dissipative systems.

15.
Otol Neurotol ; 34(9): 1642-7, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24136307

RESUMO

OBJECTIVE: The relationship between unilateral preimplantation and postimplantation auditory performance in patients undergoing sequential cochlear implantation (SCI) has not been clearly defined. A greater understanding of this relationship could affect preoperative counseling to patients regarding choice of initial side to implant. STUDY DESIGN: Retrospective case series. SETTING: Tertiary otologic practice. PATIENTS: Adult/pediatric SCI recipients. OUTCOME MEASURES: Unilateral auditory performance preimplantation and postimplantation was assessed. To compare interaural preimplantation performance, we defined a "better-hearing ear" as better pure tone average or speech awareness/reception threshold by at least 10 dB or open/closed-set speech perception score at least 10 percentage points higher. RESULTS: Ninety patients underwent SCI from 1997 to 2011; 34 children and 22 adults with at least 6 months of bilateral implant use underwent further analysis. Preoperatively, the first-implanted ear was better hearing in 6 cases, poorer hearing in 15 cases, and equal hearing in 35 individuals. The proportion of SCI recipients exhibiting better long-term performance of the first-implanted ear was not significantly different from the proportion exhibiting equal or better performance of the second-implanted ear (p = 0.79, χ²), irrespective of preoperative hearing status. The first-implanted ear exhibited better closed/open-set speech perception scores in 41% (9/22) adult and 59% (20/34) pediatric patients at a mean most recent test point of 25 and 39 months, respectively. CONCLUSION: Preimplantation unilateral hearing status was not found to influence relative interaural performance differences after SCI. This finding highlights the relative unimportance of preoperative audiometry and speech recognition scores for guiding clinical decisions regarding implant ear selection.


Assuntos
Implante Coclear , Perda Auditiva Bilateral/cirurgia , Percepção da Fala/fisiologia , Adolescente , Adulto , Audiometria , Criança , Implantes Cocleares , Feminino , Perda Auditiva Bilateral/fisiopatologia , Testes Auditivos , Humanos , Masculino , Estudos Retrospectivos , Resultado do Tratamento
16.
Acta otorrinolaringol. cir. cabeza cuello ; 41(1): 32-35, ene.-mar. 2013. ilus
Artigo em Espanhol | LILACS | ID: lil-694374

RESUMO

Introducción: La cirugía de implante coclear, como cualquier otro acto quirúrgico, puede asociarse a complicaciones inherentes al procedimiento o por un fallo atribuible al dispositivo. Objetivo: Identificar y reportar la tasa de complicaciones asociadas a la implantación coclear en menores de 18 años atendidos en el programa de implante coclear en una institución en Bogotá, Colombia. Diseño: Estudio retrospectivo. Métodos: Se incluyeron pacientes a quienes se les realizaron implantes cocleares pediátricos en el período 1994 al 2011. Se analiza en este estudio a los que recibieron implante coclear a la edad de 18 años o menos. Desenlaces principales: tasa global de complicaciones; tasa discriminada de complicaciones por tipo: médico-quirúrgica, y complicaciones atribuibles a fallo del dispositivo. Resultados: Del total de implantes cocleares (920) realizados durante el período de estudio, se selecciona el grupo con edad ≤ 18 años a la fecha del implante, 598 (65%). Total complicaciones identificadas: 49 (8,2%). Complicaciones médico-quirúrgicas: 15 (2,5%). Fallos relacionados con el dispositivo: 5,7%. Conclusiones: La tasa global de complicaciones y fallos identificada en este estudio se asemeja a la reportada por diferentes estudios, la cual varía entre el 5 y el 13% …


Introduction: Cochlear implant surgery, like any surgery, can be associated with complications inherent to the procedure or a failure attributable to the device. Objective: To identify and report the rate of complications associated with cochlear implantation in children under 18 years who presented to the cochlear implant program at a school in Bogota, Colombia. Design: Retrospective. Methods: Patients who underwent pediatric cochlear implants performed in the period 1994-2011. Is analyzed in this study who received cochlear implant at the age of 18 years or less. Main outcome measures: overall complication rate, rate of complications discriminated by type: medical-surgical complications due to device failure. Results: A total of cochlear implants (920) performed during the study period is selected age group ≤ 18 years at the time of implantation, 598 (65%). Total complications identified: 49 (8.2%). Medical-surgical complications: 15 (2.5%). Device-related failures: 5.7%. Conclusions: The overall rate of complications and failures identified in this study is similar to that reported by different studies, which varies between 5 and 13%…


Assuntos
Adolescente , Implante Coclear , Implantes Cocleares/classificação , Implantes Cocleares/efeitos adversos , Implantes Cocleares/história , Implantes Cocleares/tendências , Implantes Cocleares
17.
Acta otorrinolaringol. cir. cabeza cuello ; 40(3): 194-201, jul.-sept. 2012. ilus
Artigo em Espanhol | LILACS | ID: lil-683635

RESUMO

Objetivo: presentar la experiencia de una institución en la rehabilitación de pacientes con pérdida auditiva utilizando el implante de oído medio Vibrant Soundbridge® (VSB). Diseño: estudio retrospectivo. Materiales y métodos: se revisaron registros médicos, quirúrgicos y audiológicos de pacientes a los que se les implantó el sistema Vibrant Soundbridge (VSB), evaluando la ganancia auditiva establecida por la diferencia en los promedios de las frecuencias 0.5 a 3 kHz en la audiometría tonal postimplante con el sistema y sin él. Se evaluó también la satisfacción de uso con el dispositivo mediante la encuesta Escala de Satisfacción de Audición con Dispositivo (HDSS, Hearing Device Satisfaction Scale). Realizamos comparación de desenlaces audiológicos con una población de usuarios de similares características del sistema osteointegrado BAHA®. Resultados: 25 pacientes con pérdida auditiva predominantemente mixta recibieron un implante VSB colocando el Transductor de Masa Flotante (FMT) en ventana redonda en 23 casos (92%). La ganancia auditiva promedio fue de 36 ± 16 decibeles (dB). No se identificaron diferencias significativas en la ganancia auditiva entre los procesadores AP404-36 dB y Amadé-38 dB, p = 0.6. La ganancia auditiva en el grupo de usuarios del sistema BAHA fue de 37 dB y la discriminación de lenguaje a 65 dB fue de 93% y 100% para VSB y BAHA® respectivamente. En ambos sistemas el puntaje global de satisfacción fue de 4/5.


Objective: Present the institutional experience on the auditory rehabilitation of patients implanted with the middle ear prosthesis Vibrant Soundbridge®. Design: Retrospective study of a cases series. Materials and Methods: Medical, surgical and audiological charts review of patients implanted with the middle ear system VSB. Hearing gain was established by the mean differences calculated on 0.5 to 3 kHz in the pure tone audiometries pre and post implantation, with and without the device. Satisfaction with the device was assessed with the Hearing Device Satisfaction Scale tool. In addition, audiological and satisfaction comparison with a population with similar characteristics of BAHA implant users was made. Results: 25 patients with conductive and mixed hearing loss were implanted with the VSB, placing the FMT on the round window in 23cases (92%). Mean auditory gain was 36 ± 16 decibels (dB). There were no significance gains between processors AP404-36 dB and Amadé-38 dB, p = 0.6. Mean auditory gain in the BAHA® users was 37 dB; speech discrimination at 65 dB was 93% and 100% for VSB and BAHA® users respectively. Overall satisfaction score for both systems was 4/5. Conclusion: The middle ear implant system VSB gives a satisfactory hearing gain to patients with moderate mixed hearing loss comparable with the BAHA® as well in satisfaction and quality of life issues.


Assuntos
Humanos , Implantes Auditivos de Tronco Encefálico , Prótese Ossicular , Surdez
18.
Phys Rev E Stat Nonlin Soft Matter Phys ; 84(6 Pt 2): 066201, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22304172

RESUMO

We study the behavior of the spectra corresponding to quantum systems subjected to a contractive noise, i.e., the environment reduces the accessible phase space of the system, but the total probability is conserved. We find that the number of long-lived resonances grows as a power law in h, but surprisingly there is no relationship between the exponent of this power law and the fractal dimension of the corresponding classical attractor. This is in disagreement with the predictions of the fractal Weyl law which has been established for open systems, where the probability is lost under the effect of a projective opening.

19.
Phys Rev E Stat Nonlin Soft Matter Phys ; 81(4 Pt 2): 047201, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20481861

RESUMO

We study the stability of classical structures in chaotic systems when a dissipative quantum evolution takes place. We consider a paradigmatic model, the quantum baker map in contact with a heat bath at finite temperature. We analyze the behavior of the purity, fidelity and Husimi distributions corresponding to initial states localized on short periodic orbits (scar functions) and map eigenstates. Scar functions, that have a fundamental role in the semiclassical description of chaotic systems, emerge as robust relative to other states (which are localized on classical structures) against environmental perturbations. Also, purity and fidelity show a complementary behavior as decoherence measures.

20.
IEEE Trans Inf Technol Biomed ; 12(6): 714-22, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-19000950

RESUMO

Most of the biomedicine text mining approaches do not deal with specific cause--effect patterns that may explain the discoveries. In order to fill this gap, this paper proposes an effective new model for text mining from biomedicine literature that helps to discover cause--effect hypotheses related to diseases, drugs, etc. The supervised approach combines Bayesian inference methods with natural-language processing techniques in order to generate simple and interesting patterns. The results of applying the model to biomedicine text databases and its comparison with other state-of-the-art methods are also discussed.


Assuntos
Armazenamento e Recuperação da Informação/métodos , Indexação e Redação de Resumos , Algoritmos , Inteligência Artificial , Teorema de Bayes , Sistemas de Gerenciamento de Base de Dados , Bases de Dados Bibliográficas , Bases de Dados Factuais , Processamento de Linguagem Natural , Redes Neurais de Computação , Publicações Periódicas como Assunto
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