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1.
Neurologia (Engl Ed) ; 39(3): 226-234, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37442428

RESUMO

INTRODUCTION: Cerebral venous thrombosis (CVT) is an uncommon cause of stroke that mainly affects young adults. Early, accurate diagnosis can reduce the rate and severity of complications. OBJECTIVE: The aim of this study was to analyse the clinical characteristics, management, and treatment of CVT in different centres in Spain. METHODS: We conducted a multicentre, retrospective, descriptive study of patients hospitalised due to CVT between 2008 and 2017 at 10 Spanish centres. RESULTS: We included 256 patients, with a mean age (SD) of 49.8 (18.7) years; 51% of patients were women. The most frequent symptoms were headache (73%), focal deficits (50%), epileptic seizures (33%), and encephalopathy (21%). The most frequent localisations were the superior sagittal sinus (12.5%), the transverse sinus (10.9%), and 2 or more sinuses or veins (66.4%). Thrombophilia was the most frequent known aetiology (24%), and was most commonly associated with the prothrombin G20210A mutation (19%). Forty-six percent of patients were treated with antithrombotics for 3 to 6 months, 21% for one year, and 22.6% required indefinite anticoagulation. Endovascular therapy was performed in 5% of cases, and 33% required neurosurgery. Regarding outcomes, 75% of patients were independent at 3 months (modified Rankin Scale [mRS] score ≤ 2), with papilloedema (P =  .03), focal deficits (P = .001), and encephalopathy (P < .001) showing a statistically significant association with poor prognosis (mRS > 3). The in-hospital mortality rate was 4.3%, with a 3-month mortality rate of 6.3%. CONCLUSION: The diverse risk factors and variable presentation of CVT represent a challenge in the diagnosis and treatment of this condition. To improve prognosis and reduce mortality, it is essential to establish management protocols for this entity.


Assuntos
Trombose Intracraniana , Acidente Vascular Cerebral , Trombose Venosa , Adulto Jovem , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Estudos Retrospectivos , Espanha , Trombose Venosa/terapia , Trombose Venosa/tratamento farmacológico , Trombose Intracraniana/terapia , Trombose Intracraniana/tratamento farmacológico
2.
Rev Neurol ; 77(10): 253-257, 2023 11 16.
Artigo em Espanhol | MEDLINE | ID: mdl-37962537

RESUMO

INTRODUCTION: Vertebrobasilar stroke can be a diagnostic challenge. Bilateral vocal cord paralysis is very rare as a manifestation of acute stroke, yet it is potentially life-threatening because of the possibility of acute airway obstruction. No cases of bilateral vocal cord paralysis have been reported as a presenting symptom of acute stroke of mixed central and peripheral neurological aetiology. CASE REPORT: An 88-year-old woman with dysphonia resulting from paralysis of the right vocal cord following a thyroidectomy presented with sudden onset of vertigo, dysmetria and mild dysarthria (National Institutes of Health Stroke Scale: 2) associated with arterial hypertension. An urgent brain computed tomography (CT) scan evidenced distal occlusive thrombosis of the left vertebral artery without established ischaemia. Due to the improvement of symptoms achieved with control of her blood pressure, revascularisation therapy was not performed. Four hours later, the patient suddenly developed inspiratory stridor and severe respiratory failure due to bilateral vocal cord paralysis with complete airway obstruction. An urgent tracheotomy was performed, which resulted in an improvement in her breathing. A control brain CT scan performed at 24 hours showed established infarction in the left hemicerebellum and lateral medullary region, consistent with the territory of the left posterior inferior cerebellar artery. CONCLUSION: Our case illustrates the possibility of the rare occurrence of acute bilateral vocal cord paralysis in the context of acute stroke in conjunction with chronic peripheral involvement of the recurrent laryngeal nerve. Although exceptional, it exemplifies the potential risk associated with vertebrobasilar strokes. A more aggressive reperfusion therapy may be appropriate in these cases, despite an initially mild deficit, because of the possibility of progression to life-threatening complications.


TITLE: Parálisis bilateral de las cuerdas vocales con obstrucción aguda de la vía aérea y traqueotomía urgente en una paciente con ictus vertebrobasilar agudo.Introducción. El ictus vertebrobasilar puede suponer un reto diagnóstico. La parálisis bilateral de las cuerdas vocales como manifestación de ictus agudo es muy rara, pero potencialmente mortal, por la posibilidad de obstrucción aguda de la vía aérea. No hay casos descritos de parálisis bilateral de las cuerdas vocales como presentación de ictus agudo de etiología neurológica mixta central y periférica. Caso clínico. Mujer de 88 años con disfonía secuelar a parálisis de la cuerda vocal derecha postiroidectomía que presentó un cuadro brusco de vértigo, dismetría y disartria leve (National Institutes of Health Stroke Scale: 2) asociado a hipertensión arterial. La tomografía computarizada cerebral urgente demostró trombosis distal oclusiva de la arteria vertebral izquierda sin isquemia establecida. Por mejoría sintomática con control tensional, no se realizó terapia de revascularización. Cuatro horas después, la paciente desarrolló de forma brusca estridor inspiratorio e insuficiencia respiratoria grave por parálisis bilateral de las cuerdas vocales con obstrucción completa de la vía aérea. Se realizó una traqueotomía urgente con mejoría respiratoria. Una tomografía computarizada cerebral de control a las 24 horas mostró un infarto establecido en el hemicerebelo izquierdo y la región bulbar lateral, congruente con territorio de la arteria cerebelosa posterior inferior izquierda. Conclusión. Nuestro caso ilustra la posibilidad de la rara aparición de una parálisis bilateral aguda de las cuerdas vocales en el contexto de un ictus agudo junto con una afectación periférica crónica del nervio recurrente laríngeo. Aunque es excepcional, ejemplifica el potencial riesgo asociado a los ictus vertebrobasilares. Un tratamiento más agresivo de reperfusión podría ser adecuado en estos casos, pese a un déficit inicialmente leve, por la posibilidad de progresar a complicaciones vitales.


Assuntos
Obstrução das Vias Respiratórias , Acidente Vascular Cerebral , Paralisia das Pregas Vocais , Humanos , Estados Unidos , Feminino , Idoso de 80 Anos ou mais , Traqueotomia , Paralisia das Pregas Vocais/complicações , Obstrução das Vias Respiratórias/etiologia , Obstrução das Vias Respiratórias/cirurgia , Pacientes , Acidente Vascular Cerebral/complicações
3.
Rev. neurol. (Ed. impr.) ; 77(10): 253-257, 16 - 30 de Noviembre 2023. ilus, tab
Artigo em Espanhol | IBECS | ID: ibc-227593

RESUMO

Introducción El ictus vertebrobasilar puede suponer un reto diagnóstico. La parálisis bilateral de las cuerdas vocales como manifestación de ictus agudo es muy rara, pero potencialmente mortal, por la posibilidad de obstrucción aguda de la vía aérea. No hay casos descritos de parálisis bilateral de las cuerdas vocales como presentación de ictus agudo de etiología neurológica mixta central y periférica. Caso clínico Mujer de 88 años con disfonía secuelar a parálisis de la cuerda vocal derecha postiroidectomía que presentó un cuadro brusco de vértigo, dismetría y disartria leve (National Institutes of Health Stroke Scale: 2) asociado a hipertensión arterial. La tomografía computarizada cerebral urgente demostró trombosis distal oclusiva de la arteria vertebral izquierda sin isquemia establecida. Por mejoría sintomática con control tensional, no se realizó terapia de revascularización. Cuatro horas después, la paciente desarrolló de forma brusca estridor inspiratorio e insuficiencia respiratoria grave por parálisis bilateral de las cuerdas vocales con obstrucción completa de la vía aérea. Se realizó una traqueotomía urgente con mejoría respiratoria. Una tomografía computarizada cerebral de control a las 24 horas mostró un infarto establecido en el hemicerebelo izquierdo y la región bulbar lateral, congruente con territorio de la arteria cerebelosa posterior inferior izquierda. Conclusión Nuestro caso ilustra la posibilidad de la rara aparición de una parálisis bilateral aguda de las cuerdas vocales en el contexto de un ictus agudo junto con una afectación periférica crónica del nervio recurrente laríngeo. Aunque es excepcional, ejemplifica el potencial riesgo asociado a los ictus vertebrobasilares. Un tratamiento más agresivo de reperfusión podría ser adecuado en estos casos, pese a un déficit inicialmente leve, por la posibilidad de progresar a complicaciones vitales. (AU)


INTRODUCTION Vertebrobasilar stroke can be a diagnostic challenge. Bilateral vocal cord paralysis is very rare as a manifestation of acute stroke, yet it is potentially life-threatening because of the possibility of acute airway obstruction. No cases of bilateral vocal cord paralysis have been reported as a presenting symptom of acute stroke of mixed central and peripheral neurological aetiology. CASE REPORT An 88-year-old woman with dysphonia resulting from paralysis of the right vocal cord following a thyroidectomy presented with sudden onset of vertigo, dysmetria and mild dysarthria (National Institutes of Health Stroke Scale: 2) associated with arterial hypertension. An urgent brain computed tomography (CT) scan evidenced distal occlusive thrombosis of the left vertebral artery without established ischaemia. Due to the improvement of symptoms achieved with control of her blood pressure, revascularisation therapy was not performed. Four hours later, the patient suddenly developed inspiratory stridor and severe respiratory failure due to bilateral vocal cord paralysis with complete airway obstruction. An urgent tracheotomy was performed, which resulted in an improvement in her breathing. A control brain CT scan performed at 24 hours showed established infarction in the left hemicerebellum and lateral medullary region, consistent with the territory of the left posterior inferior cerebellar artery. CONCLUSION. Our case illustrates the possibility of the rare occurrence of acute bilateral vocal cord paralysis in the context of acute stroke in conjunction with chronic peripheral involvement of the recurrent laryngeal nerve. Although exceptional, it exemplifies the potential risk associated with vertebrobasilar strokes. A more aggressive reperfusion therapy may be appropriate in these cases, despite an initially mild deficit, because of the possibility of progression to life-threatening complications. (AU)


Assuntos
Humanos , Feminino , Idoso de 80 Anos ou mais , Paralisia das Pregas Vocais/complicações , Paralisia das Pregas Vocais/diagnóstico por imagem , Paralisia das Pregas Vocais/diagnóstico , Paralisia das Pregas Vocais/terapia , Obstrução das Vias Respiratórias , Traqueotomia , /complicações , /terapia , Infarto Cerebral
4.
Phys Rev E ; 106(4): L043101, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36397566

RESUMO

The modulation instability is a focusing mechanism responsible for the formation of strong wave localizations not only on the water surface, but also in a variety of nonlinear dispersive media. Such dynamics is initiated from the injection of sidebands, which translate into an amplitude modulation of the wave field. The nonlinear stage of unstable wave evolution can be described by exact solutions of the nonlinear Schrödinger equation (NLSE). In that case, the amplitude modulation of such coherent extreme wave structures is connected to a particular phase-shift seed in the carrier wave. In this Letter, we show that phase-shift localization applied to the background, excluding any amplitude modulation excitation, can indeed trigger extreme events. Such rogue waves can be for instance generated by considering the parametrization of fundamental breathers, and thus by seeding only the local phase-shift information to the regular carrier wave. Our wave tank experiments show an excellent agreement with the expected NLSE hydrodynamics and confirm that even though delayed in their evolution, breather-type extreme waves can be generated from a purely regular wave train. Such a focusing mechanism awaits experimental confirmation in other nonlinear media, such optics, plasma, and Bose-Einstein condensates.

5.
Neurologia (Engl Ed) ; 2021 Sep 09.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-34511275

RESUMO

INTRODUCTION: Cerebral venous thrombosis (CVT) is an uncommon cause of stroke that mainly affects young adults. Early, accurate diagnosis can reduce the rate and severity of complications. OBJECTIVE: The aim of this study was to analyse the clinical characteristics, management, and treatment of CVT in different centres in Spain. METHODS: We conducted a multicentre, retrospective, descriptive study of patients hospitalised due to CVT between 2008 and 2017 at 11 Spanish centres. RESULTS: We included 256 patients, with a mean age (SD) of 49.8 (18.7) years; 51% of patients were women. The most frequent symptoms were headache (73%), focal deficits (50%), epileptic seizures (33%), and encephalopathy (21%). The most frequent localisations were the superior sagittal sinus (12.5%), the transverse sinus (10.9%), and 2 or more sinuses or veins (66.4%). Thrombophilia was the most frequent known aetiology (24%), and was most commonly associated with the prothrombin G20210A mutation (19%). Forty-six percent of patients were treated with antithrombotics for 3-6 months, 21% for one year, and 22.6% required indefinite anticoagulation. Endovascular therapy was performed in 5% of cases, and 33% required neurosurgery. Regarding outcomes, 75% of patients were independent at 3 months (modified Rankin Scale [mRS] score ≤ 2), with papilloedema (P=.03), focal deficits (P=.001), and encephalopathy (P <.001) showing a statistically significant association with poor prognosis (mRS> 3). The in-hospital mortality rate was 4.3%, with a 3-month mortality rate of 6.3%. CONCLUSION: The diverse risk factors and variable presentation of CVT represent a challenge in the diagnosis and treatment of this condition. To improve prognosis and reduce mortality, it is essential to establish management protocols for this entity.

6.
Eur J Neurol ; 27(12): 2439-2445, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-32638466

RESUMO

BACKGROUND AND PURPOSE: The existence of contraindications to intravenous thrombolysis (IVT) is considered a criterion for direct transfer of patients with suspected acute stroke to thrombectomy-capable centers in the prehospital setting. Our aim was to assess the utility of this criterion in a setting where routing protocols are defined by the Madrid - Direct Referral to Endovascular Center (M-DIRECT) prehospital scale. METHODS: This was a post hoc analysis of the M-DIRECT study. Reported contraindications to IVT were retrospectively collected from emergency medical services reports and categorized into late window, anticoagulant treatment and other contraindications. Final diagnosis and treatment rates were compared between patients with and without reported IVT contraindications and according to anticoagulant treatment or late window categories. RESULTS: The M-DIRECT study included 541 patients. Reported IVT contraindications were present in 227 (42.0%) patients. Regarding final diagnosis no significant differences were found between patients with or without reported IVT contraindications: ischaemic stroke (any) 65.6% vs. 62.1%, ischaemic stroke with large vessel occlusion (LVO) 32.2% vs. 28.3%, hemorrhagic stroke 15.4% vs. 15.6%, stroke mimic 18.9% vs. 22.3% respectively. Amongst patients with LVO, endovascular thrombectomy (EVT) was performed less often in the presence of IVT contraindications (56.2% vs. 74.2%). M-DIRECT-positive patients had higher rates of LVO and EVT compared with M-DIRECT-negative patients independent of reported IVT contraindications. CONCLUSIONS: Reported IVT contraindications alone do not increase EVT likelihood and should not be considered to determine routing in urban stroke networks.


Assuntos
Isquemia Encefálica , Serviços Médicos de Emergência , Procedimentos Endovasculares , Acidente Vascular Cerebral , Isquemia Encefálica/tratamento farmacológico , Contraindicações , Fibrinolíticos , Humanos , Estudos Retrospectivos , Acidente Vascular Cerebral/tratamento farmacológico , Trombectomia , Terapia Trombolítica , Resultado do Tratamento , Triagem
11.
Opt Lett ; 42(15): 3044-3047, 2017 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-28957241

RESUMO

We investigate analytically, numerically, and experimentally the spectral broadening of pulses that undergo the formation of dispersive shocks, addressing in particular pulses in the range of tens of ps generated via electro-optic modulation of a continuous-wave laser. We give an analytical estimate of the maximal spectral extension and show that super-Gaussian waveforms favor the generation of flat-topped spectra. We also show that the weak residual background of the modulator produces undesired spectral ripples. Spectral measurements confirm our estimates and agree well with numerical integration of the nonlinear Schrödinger equation.

12.
Opt Lett ; 42(3): 435-438, 2017 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-28146495

RESUMO

We experimentally investigate the round-trip-to-round-trip dynamics of the modulation instability spectrum in a passive fiber-ring cavity presenting an inhomogeneous dispersion profile. By implementing a real-time spectroscopy technique, we are able to record successive single-shot spectra, which display the evolution of the system toward a stationary state. We find that the two instability regimes (Turing and Faraday) that compete in this kind of inhomogeneous cavity not only differ by their characteristic frequency but also by their dynamical behavior. The dynamic transition between those two regimes of instability is also presented.

13.
Phys Rev Lett ; 117(14): 144102, 2016 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-27740809

RESUMO

We observe the dispersive breaking of cosine-type long waves [Phys. Rev. Lett. 15, 240 (1965)] in shallow water, characterizing the highly nonlinear "multisoliton" fission over variable conditions. We provide new insight into the interpretation of the results by analyzing the data in terms of the periodic inverse scattering transform for the Korteweg-de Vries equation. In a wide range of dispersion and nonlinearity, the data compare favorably with our analytical estimate, based on a rigorous WKB approach, of the number of emerging solitons. We are also able to observe experimentally the universal Fermi-Pasta-Ulam recurrence in the regime of moderately weak dispersion.

14.
Phys Rev Lett ; 117(1): 013901, 2016 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-27419569

RESUMO

We show that the nonlinear stage of modulational instability induced by parametric driving in the defocusing nonlinear Schrödinger equation can be accurately described by combining mode truncation and averaging methods, valid in the strong driving regime. The resulting integrable oscillator reveals a complex hidden heteroclinic structure of the instability. A remarkable consequence, validated by the numerical integration of the original model, is the existence of breather solutions separating different Fermi-Pasta-Ulam recurrent regimes. Our theory also shows that optimal parametric amplification unexpectedly occurs outside the bandwidth of the resonance (or Arnold tongues) arising from the linearized Floquet analysis.

15.
Opt Lett ; 41(11): 2656-9, 2016 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-27244438

RESUMO

We experimentally report the observation of dispersive shock waves from a short pulse superimposed onto a small continuous wave background in optical fibers. We show that the background allows us to strongly enhance the extension and contrast of the oscillatory wave train inherent to the dispersive shock. More than seven periods of oscillations with high contrast are observed experimentally and confirmed with numerical simulations. The dynamics of the process are simply explained from spectro-temporal representations.

16.
Actas urol. esp ; 40(3): 173-182, abr. 2016. ilus, graf, tab
Artigo em Espanhol | IBECS | ID: ibc-150988

RESUMO

Objetivo: Explorar el impacto de la incontinencia urinaria de urgencia (IUU) en el bienestar de los pacientes no institucionalizados con vejiga hiperactiva (VH) en una muestra de la comunidad. Métodos: Se llevó a cabo un estudio transversal basado en Internet en la población general, incluyendo hombres y mujeres, >18 años de edad. Los pacientes con probable VH se identificaron utilizando un algoritmo validado junto con una puntuación ≥8 en la escala OAB-V8. La presencia de comportamiento de adaptación se consideró determinante para el diagnóstico clínico de la VH. Se determinó bienestar individual a través de una batería de mediciones de resultados comunicados por el paciente (PRO) incluida la evaluación de la calidad de vida relacionada con la salud (EQ-5D), alteraciones del sueño (sueño MOS) y satisfacción con la vida (LISAT-8). Los pacientes fueron agrupados de acuerdo con el número de episodios diarios de IUU (gravedad IUU): 0 (VH seca), 1, 2-3 o ≥4. Se realizó un análisis multivariado para evaluar los factores que afectan de forma independiente la calidad de vida. Resultados: Un total de 396 pacientes (52,5% mujeres, media de edad: 55,3 [11,1] años, OAB-V8 puntuación media: 14,5 [7,9]) de 2.035 sujetos participantes de la población general cumplieron los criterios de VH: 203 (51,3%) con 0 episodios; 119 (30,1%) con 1; 52 (13,1%) con 2 o 3 y 22 (5,6%) con >4 episodios. Se encontró una asociación ajustada lineal estadísticamente significativa entre el número de episodios de IUU y las puntuaciones de PRO. Los participantes con más episodios tenían peores perfiles de salud y calidad de autoevaluación de la vida, peor satisfacción con la vida, más trastornos del sueño y menos horas de sueño por noche. El número de episodios de incontinencia fue factor independiente para afectar a la calidad de vida utilizando los cuestionarios LISAT-8 y MOS. Conclusión: La gravedad de la IUU se asoció significativamente con peor bienestar individual en los sujetos con VH en una muestra comunitaria en España


Objective: To explore the impact of urgency urinary incontinence (UUI) on well-being in non-institutionalized patients with overactive bladder (OAB) in a community sample. Methods: A cross-sectional web-based study was conducted in the general population, including males and females, >18 years of age. Patients with probable OAB were identified using a validated algorithm together with a score ≥8 on the OAB-V8 scale. Presence of coping behavior was considered determinant for the clinical diagnosis of OAB. Individual well-being was determined through a battery of patient-reported outcomes (PRO) measurements including assessment of health-related quality of life (EQ-5D), sleep disturbances (MOS Sleep), and life satisfaction (LISAT-8). Patients were grouped according to the number of daily UUI episodes (UUI severity): 0 (dry OAB),1, 2-3, or ≥4. Multivariate analysis to evaluate factors independently affecting quality of life was undertaken. Results: A total of 396 patients (52.5% women, mean age: 55.3 [11.1] years, OAB-V8 mean score: 14.5 [7.9]) out of 2035 subjects participating from the general population met the criteria for OAB: 203 (51.3%) with 0 episodes, 119 (30.1%) with 1, 52 (13.1%) with 2 or 3, and 22 (5.6%) with ≥4 episodes. A statistically significant linear adjusted association was found between number of UUI episodes and PRO scores. Participants with more episodes had poorer health profiles and self-evaluated quality of life, worse life satisfaction, and more sleep disturbances and fewer hours of sleep per night. Number of incontinence episodes was independent factor to affect quality of life using both LISAT-8 and MOS questionnaires. Conclusion: Severity of UUI was significantly associated with poorer individual well-being in subjects with OAB in a community sample in Spain


Assuntos
Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Medidas de Resultados Relatados pelo Paciente , Incontinência Urinária , Bexiga Urinária Hiperativa/fisiopatologia , Bexiga Urinária Hiperativa/diagnóstico , Estudo Observacional , Índice de Gravidade de Doença , Estudos Transversais , Micção
17.
Actas Urol Esp ; 40(3): 173-82, 2016 Apr.
Artigo em Inglês, Espanhol | MEDLINE | ID: mdl-26811022

RESUMO

OBJECTIVE: To explore the impact of urgency urinary incontinence (UUI) on well-being in non-institutionalized patients with overactive bladder (OAB) in a community sample. METHODS: A cross-sectional web-based study was conducted in the general population, including males and females, >18 years of age. Patients with probable OAB were identified using a validated algorithm together with a score ≥8 on the OAB-V8 scale. Presence of coping behavior was considered determinant for the clinical diagnosis of OAB. Individual well-being was determined through a battery of patient-reported outcomes (PRO) measurements including assessment of health-related quality of life (EQ-5D), sleep disturbances (MOS Sleep), and life satisfaction (LISAT-8). Patients were grouped according to the number of daily UUI episodes (UUI severity): 0 (dry OAB),1, 2-3, or ≥4. Multivariate analysis to evaluate factors independently affecting quality of life was undertaken. RESULTS: A total of 396 patients (52.5% women, mean age: 55.3 [11.1] years, OAB-V8 mean score: 14.5 [7.9]) out of 2035 subjects participating from the general population met the criteria for OAB: 203 (51.3%) with 0episodes, 119 (30.1%) with 1, 52 (13.1%) with 2 or 3, and 22 (5.6%) with ≥4 episodes. A statistically significant linear adjusted association was found between number of UUI episodes and PRO scores. Participants with more episodes had poorer health profiles and self-evaluated quality of life, worse life satisfaction, and more sleep disturbances and fewer hours of sleep per night. Number of incontinence episodes was independent factor to affect quality of life using both LISAT-8 and MOS questionnaires. CONCLUSION: Severity of UUI was significantly associated with poorer individual well-being in subjects with OAB in a community sample in Spain.


Assuntos
Medidas de Resultados Relatados pelo Paciente , Bexiga Urinária Hiperativa/fisiopatologia , Estudos Transversais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Bexiga Urinária Hiperativa/diagnóstico , Micção
18.
Opt Express ; 23(24): 30861-71, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26698719

RESUMO

We investigate multi-wave mixing associated with the strongly pump depleted regime of induced modulation instability (MI) in optical fibers. For a complete transfer of pump power into the sideband modes, we theoretically and experimentally demonstrate that it is necessary to use a much lower seeding modulation frequency than the peak MI gain value. Our experiment shows that, at such optimal modulation frequency, a record 95 % of the output pump power is frequency converted into the comb of sidebands, in good quantitative agreement with analytical predictions based on the simplest exact breather solution of the nonlinear Schrodinger ¨ equation.

19.
Nat Commun ; 6: 8131, 2015 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-26348292

RESUMO

Understanding turbulent flows arising from random dispersive waves that interact strongly through nonlinearities is a challenging issue in physics. Here we report the observation of a characteristic transition: strengthening the nonlocal character of the nonlinear response drives the system from a fully turbulent regime, featuring a sea of coherent small-scale dispersive shock waves (shocklets) towards the unexpected emergence of a giant collective incoherent shock wave. The front of such global incoherent shock carries most of the stochastic fluctuations and is responsible for a peculiar folding of the local spectrum. Nonlinear optics experiments performed in a solution of graphene nano-flakes clearly highlight this remarkable transition. Our observations shed new light on the role of long-range interactions in strongly nonlinear wave systems operating far from thermodynamic equilibrium, which reveals analogies with, for example, gravitational systems, and establishes a new scenario that can be common to many turbulent flows in photonic quantum fluids, hydrodynamics and Bose-Einstein condensates.

20.
Sci Rep ; 4: 7285, 2014 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-25468032

RESUMO

We investigate wave collapse ruled by the generalized nonlinear Schrödinger (NLS) equation in 1+1 dimensions, for localized excitations with non-zero background, establishing through virial identities a new criterion for blow-up. When collapse is arrested, a semiclassical approach allows us to show that the system can favor the formation of dispersive shock waves. The general findings are illustrated with a model of interest to both classical and quantum physics (cubic-quintic NLS equation), demonstrating a radically novel scenario of instability, where solitons identify a marginal condition between blow-up and occurrence of shock waves, triggered by arbitrarily small mass perturbations of different sign.

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