On the large values of the Wiener process

AbstractLet (W(t), t⩾0), be a standard Wiener process and define •M+ (t) = max{W(u): u⩽t},•M−(t) = max{−W(u): u⩽t},•Z(t) = max{u ⩽ t: W(u) = 0}.We investigate the asymptotic behaviour of Z(t) and M−(t) under the condition that M+(t) (or, equivalently, W(t)) gets very large, i.e. as large as indicated by the law of iterated logarithm

Prevalence, Determinants, and Consequences of Vestibular Hypofunction. Results From the KORA-FF4 Survey

Objective: Uni- or bilateral vestibular hypofunction (VH) impairs balance and mobility, and may specifically lead to injury from falls and to disability. The extent of this problem in the general population is still unknown and most likely to be underestimated. Objective of this study was to determine the prevalence, determinants, and consequences of VH in the general population.Methods: Data originates from the cross-sectional second follow-up (FF4) in 2013/14 of the KORA (Cooperative Health Research in the Region of Augsburg)-S4 study (1999–2001) from Southern Germany. This was a random sample of the target population consisting of all residents of the region aged 25–74 years in 1999. We included all participants who reported moderate or severe vertigo or dizziness during the last 12 months and a random sub-sample of participants representative for the general population without vertigo or dizziness during the last 12 months were tested. VH was assessed with the Video-Head Impulse Test (vHIT). Trained examiners applied high-acceleration, small-amplitude passive head rotations (“head impulses”) to the left and right in the plane of the horizontal semicircular canals while participants fixated a target straight ahead. During head impulses, head movements were measured with inertial sensors, eye movements with video-oculography (EyeSeeCam vHIT).Results: A total of 2,279 participants were included (mean age 60.8 years, 51.6% female), 570 (25.0%) with moderate or severe vertigo or dizziness during the last 12 months. Of these, 450 were assessed with vHIT where 26 (5.8%) had unilateral VH, and 16 (3.6%) had bilateral VH. Likewise, 190 asymptomatic participants were tested. Of these 5 (2.6%) had unilateral VH, and 2 (1.1%) had bilateral VH. Prevalence of uni- or bilateral VH among tested symptomatic participants was 2.4% in those < 48 years, and 32.1% in individuals aged 79 and over. Age-adjusted prevalence was 6.7% (95% CI 4.8%; 8.6%). VH was associated with worse health, falls, hearing loss, hearing impairment, and ear pressure.Conclusion: VH may affect between 53 and 95 million adults in Europe and the US. While not all affected persons will experience the full spectrum of symptoms and consequences, adequate diagnostic and therapeutic measures should become standard of care to decrease the burden of disease

Gender differences in the association between grip strength and mortality in older adults: results from the KORA-age study

Published version. Source at http://doi.org/10.1186/s12877-016-0381-4. License CC BY 4.0.Background: Reduced muscular strength in the old age is strongly related to activity impairment and mortality. However, studies evaluating the gender-specific association between muscularity and mortality among older adults are lacking. Thus, the objective of the present study was to examine gender differences in the association between muscular strength and mortality in a prospective population-based cohort study. Methods: Data used in this study derived from the Cooperative Health Research in the Region of Augsburg (KORA)-Age Study. The present analysis includes 1,066 individuals (mean age 76 ± 11 SD years) followed up over 3 years. Handgrip strength was measured using the Jamar Dynamometer. A Cox proportional hazard model was used to determine adjusted hazard ratios of mortality with 95% confidence intervals (95% CI) for handgrip strength. Potential confounders (i.e. age, nutritional status, number of prescribed drugs, diseases and level of physical activity) were pre-selected according to evidence-based information. Results: During the follow-up period, 56 men (11%) and 39 women (7%) died. Age-adjusted mortality rates per 1,000 person years (95% CI) were 77 (59–106), 24 (13–41) and 14 (7–30) for men and 57 (39–81), 14 (7–27) and 1 (0–19) for women for the first, second and third sex-specific tertile of muscular strength, respectively. Low handgrip strength was significantly associated with all-cause mortality among older men and women from the general population after controlling for significant confounders. Hazard ratios (95% CI) comparing the first and second tertile to the third tertle were 3.33 (1.53–7.22) and 1.42 (0.61-3.28), respectively. Respective hazard ratios (95% CI) for mortality were higher in women than in men ((5.23 (0.67–40.91) and 2.17 (0.27–17.68) versus 2.36 (0.97–5.75) and 0. 97 (0.36–2.57)). Conclusions: Grip strength is inversely associated with mortality risk in older adults, and this association is independent of age, nutritional status, number of prescribed drugs, number of chronic diseases and level of physical activity. The association between muscular strength and all-cause mortality tended to be stronger in women. It seems to be particularly important for the weakest to enhance their levels of muscular strength in order to reduce the risk of dying early

A coupling matrix vision for mobile filtering devices with micro-acoustic wave technologies. A systematic approach

Con el espectro radioeléctrico cada vez más saturado, los filtros y duplexores son elementos claves de la tecnología en el mercado de dispositivos discretos para la telefonía móvil. El segmento de usuario de los sistemas de comunicaciones inalámbricas aprovecha las destacadas propiedades de los dispositivos filtrantes basados en resonadores acústicos. Generalmente, el diseño de dispositivos de onda acústica ha sido asumido por técnicas de optimización debido a las restrictivas limitaciones impuestas por la viabilidad tecnológica de los resonadores SAW y BAW, así como las exigentes especificaciones eléctricas. Una respuesta de transmisión muy restrictiva y factores tecnológicos muy limitantes conducen a hacer el diseño más y más complejo y una tarea muy desafiante. El objetivo del trabajo está enfocado en facilitar el diseño de filtros/duplexores y hacerlo más eficiente. En consecuencia, la formulación inicial del problema se ha centrado en la viabilidad tecnológica para implementar filtros de onda acústica. Proporcionar una metodología sistemática es útil para acelerar la curva de aprendizaje de nuevos diseñadores. Los filtros de microondas con elevada selectividad son posibles si sus funciones de transferencia incorporan ceros de transmisión finitos. La introducción de nodos no-resonantes (NRN) da la posibilidad de diseñar filtros con el máximo número de ceros de transmisión finitos sin tener que implementar acoplamientos directos entre la fuente y la carga. Además, las configuraciones en línea con NRN permiten la extracción de los elementos analíticamente. La típica configuración de filtro ladder presenta similitudes características de acuerdo con las redes de prototipo en línea con nodos resonantes y no-resonantes, que son las propiedades de modularidad, para controlar los ceros de transmisión con resonadores independientes, y respuestas completamente canonícas sin acoplamiento fuente-carga directo. Los elementos de la red pasobanda son dados por ecuaciones explícitas en términos de aquellos en los prototipos en línea con NRN que pueden ser sintetizados analíticamente. Como consecuencia, es posible definir una metodología de síntesis directa para obtener los parámetros pasobanda eléctricos de un filtro RF general que está basado en resonadores acústicos. Este trabajo presenta una metodología que proporciona un procedimiento de síntesis sistemático para diseñar filtros y duplexores ladder basados en resonadores de onda micro-acústica. La metodología de diseño utiliza un enfoque nodal basado en NRN y nodos resonantes. La representación de la red mediante una matriz de acoplamiento mixta de nodos resonantes y no resonantes es capaz de gestionar de forma eficiente las restricciones tecnológicas. El procedimiento es eficiente en tiempo, preciso en los resultados y proporciona un profundo entendimiento de las particulares interacciones que se producen entre las restricciones tecnológicas y el funcionamiento del dispositivo. Un completo paquete de software, con un simulador rápido, preciso y de fácil uso, ha sido desarrollado, permitiendo obtener diseños de primera etapa exitosos. Como resultado de la metodología sistemática, hemos desarrollado un método de diseño que combina y sistemáticamente gestiona redes filtrantes compuestas de bloques de polo extraído con bloques de resonadores acoplados, es decir, celdas ladder con secciones CRF. Además, la metodología has sido extendida exitosamente para tener en cuenta el diseño de divisores de potencia con respuesta filtrante por medio de dos topologías diferentes: la configuración ladder y las secciones CRF. La metodología propuesta ofrece una solución que combina el completo cumplimiento de las máscaras de espectro con topologías preparadas para acomodar las restricciones tecnológicas de la tecnología micro-acústica. La metodología ha sido desarrollada orientada nativamente a gestionar la tecnología, como es el ajuste de la limitación en el acoplo electromagnético, y basada en fundamentos de síntesis rigurosos.With a spectrum more and more overcrowded, filters and duplexers are drivers of the technology in the discrete device mobile market. The user segment of wireless communication systems takes profit of the outstanding performance of filtering devices based on acoustic resonators. Usually, the design of acoustic wave devices have been mainly entrusted to optimization techniques because the stringent constraints imposed by the technological feasibility of SAW and BAW resonators and the challenging electrical specifications. A stringent transmission response and very restrictive technological factors lead the design to a more and more complex and challenging task. The aim of the work is focused on easing the filters/duplexers designs and making it more efficient. Consequently, the initial formulation of the problem was focused on the technological feasibility of acoustic wave filters. Providing a systematic methodology is useful to accelerate the learning curve of new entrant designers. Microwave filters with high selectivity are possible if their transfer functions incorporates finite transmission zeros. The inclusion of non-resonant nodes gives the possibility of designing filters with the maximum number of finite transmission zeros without implementing direct couplings between source and load. Furthermore, inline configuration with NRN allows the extraction of the elements analytically. The common ladder filter configuration exhibits characteristic similarities regarding inline prototype networks with resonant and non-resonant nodes, which are the property of modularity, to control transmission zeros by independent resonators, and fully canonical response without a direct source-load coupling. The elements of the lowpass prototype are given by explicit equations in terms of those in in-line prototypes with non-resonating nodes that can be synthesized analytically. As a consequence it is possible to define a direct synthesis methodology to obtain the bandpass electric parameters of a general RF filter that is based on acoustic resonators. This work presents a methodology that provides a systematic synthesis procedure for designing ladder filters and duplexers based on acoustic wave resonators. The methodology uses a nodal approach based on resonating and non-resonating nodes. The coupling matrix representation with a mix of different nature nodes, resonant and non-resonant, is able to efficiently manage the technological restrictions. The procedure is time efficient, precise in the outcomes and provides a deep understanding of the particular interactions between technological constraints and device performance. A complete software package with fast, accurate and easy-to-use simulator has been developed, enabling starting point design success. As a result of the systematic methodology, we have developed a design method that combines and systematically manages a filtering network composed of extracted-pole blocks with coupling resonators blocks, so it is ladder cells with CRF sections. Moreover, the methodology has been successfully extended to take into consideration filtering power dividers by means of two different topologies: ladder configuration and CRF sections. The proposed methodology offers a solution that combines a complete spectrum fulfillment with topologies ready to accommodate technological constraints of micro-acoustics technologies. The methodology has been developed natively oriented to manage with the technology, such as accommodating electromechanical coupling constraints, leveraged in rigorous synthesis foundations

Symptoms in unilateral vestibular hypofunction are associated with number of catch-up saccades and retinal error: results from the population-based KORA FF4 study

ObjectiveThe presence and intensity of symptoms vary in patients with unilateral vestibular hypofunction. We aimed to determine which saccadic and vestibulo-ocular reflex parameters best predict the presence of symptoms in unilateral vestibular hypofunction in order to better understand vestibular compensation and its implications for rehabilitation therapy.MethodsVideo head impulse test data were analyzed from a subpopulation of 23 symptomatic and 10 currently symptom-free participants with unilateral vestibular hypofunction, embedded in the KORA (Cooperative Health Research in the Region of Augsburg) FF4 study, the second follow-up of the KORA S4 population-based health survey (2,279 participants).ResultsA higher number of catch-up saccades, a higher percentage of covert saccades, and a larger retinal error at 200 ms after the onset of the head impulse were associated with relevant symptoms in participants with unilateral vestibular hypofunction (p = 0.028, p = 0.046, and p = 0.038, respectively). After stepwise selection, the number of catch-up saccades and retinal error at 200 ms remained in the final logistic regression model, which was significantly better than a null model (p = 0.014). Age, gender, saccade amplitude, saccade latency, and VOR gain were not predictive of the presence of symptoms.ConclusionThe accuracy of saccadic compensation seems to be crucial for the presence of symptoms in unilateral vestibular hypofunction, highlighting the role of specific gaze stabilization exercises in rehabilitation. Early saccades, mainly triggered by the vestibular system, do not seem to compensate accurately enough, resulting in a relevant retinal error and the need for more as well as more accurate catch-up saccades, probably triggered by the visual system

Dynamics of trimming the content of face representations for categorization in the brain

To understand visual cognition, it is imperative to determine when, how and with what information the human brain categorizes the visual input. Visual categorization consistently involves at least an early and a late stage: the occipito-temporal N170 event related potential related to stimulus encoding and the parietal P300 involved in perceptual decisions. Here we sought to understand how the brain globally transforms its representations of face categories from their early encoding to the later decision stage over the 400 ms time window encompassing the N170 and P300 brain events. We applied classification image techniques to the behavioral and electroencephalographic data of three observers who categorized seven facial expressions of emotion and report two main findings: (1) Over the 400 ms time course, processing of facial features initially spreads bilaterally across the left and right occipito-temporal regions to dynamically converge onto the centro-parietal region; (2) Concurrently, information processing gradually shifts from encoding common face features across all spatial scales (e.g. the eyes) to representing only the finer scales of the diagnostic features that are richer in useful information for behavior (e.g. the wide opened eyes in 'fear'; the detailed mouth in 'happy'). Our findings suggest that the brain refines its diagnostic representations of visual categories over the first 400 ms of processing by trimming a thorough encoding of features over the N170, to leave only the detailed information important for perceptual decisions over the P300

Top-down Modulations in the Visual Form Pathway Revealed with Dynamic Causal Modeling

Perception entails interactions between activated brain visual areas and the records of previous sensations, allowing for processes like figure–ground segregation and object recognition. The aim of this study was to characterize top-down effects that originate in the visual cortex and that are involved in the generation and perception of form. We performed a functional magnetic resonance imaging experiment, where subjects viewed 3 groups of stimuli comprising oriented lines with different levels of recognizable high-order structure (none, collinearity, and meaning). Our results showed that recognizable stimuli cause larger activations in anterior visual and frontal areas. In contrast, when stimuli are random or unrecognizable, activations are greater in posterior visual areas, following a hierarchical organization where areas V1/V2 were less active with “collinearity” and the middle occipital cortex was less active with “meaning.” An effective connectivity analysis using dynamic causal modeling showed that high-order visual form engages higher visual areas that generate top-down signals, from multiple levels of the visual hierarchy. These results are consistent with a model in which if a stimulus has recognizable attributes, such as collinearity and meaning, the areas specialized for processing these attributes send top-down messages to the lower levels to facilitate more efficient encoding of visual form