Observations of nonlinear run-up patterns on plane and rhythmic beach morphology

Application of non-linear forecasting and bispectral analysis to video observations of run-up over cuspate topography shows that these alongshore patterns in the morphology are accompanied by changes to the fundamental behaviour of the run-up timeseries. Nonlinear forecasting indicates that at beach cusp horns, the behaviour of swash flow is more predictable and global (meaning that characteristics of individual swash events are well represented by the behaviour of the timeseries as a whole). Conversely, at beach cusp bays, the behaviour of swash flow is less predictable and more local (meaning that the characteristics of individual swash events are best represented by the behaviour of a small fraction of the timeseries). Bispectral analysis indicates that there is a nonlinear transfer of energy from the incident wave frequency f to infragravity frequency ~f/2 which only occurs in the bay, suggesting that the local behaviour is caused by interactions between successive swash cycles which are magnified by channelling caused by the beach cusp geometry. The local behaviour and the bispectral signatures are not present in offshore measurements, and are not present in runup timeseries collected when the beach was planar. These results provide evidence that interactions between successive run-ups are a fundamental characteristic of beach cusp bays. Ultimately, these interactions could lead to the growth of an infragravity wave with an alongshore wavelength forced by the presence of beach cusps

The use of video imagery to analyse groundwater and shoreline dynamics on a dissipative beach

Groundwater seepage is known to influence beach erosion and accretion processes. However, field measurements of the variation of the groundwater seepage line (GWSL) and the vertical elevation difference between the GWSL and the shoreline are limited. We developed a methodology to extract the temporal variability of the shoreline and the wet-dry boundary using video imagery, with the overarching aim to examine elevation differences between the wet-dry boundary and the shoreline position in relation to rainfall and wave characteristics, during a tidal cycle. The wet-dry boundary was detected from 10-minute time-averaged images collected at Ngaranui Beach, Raglan, New Zealand. An algorithm discriminated between the dry and wet cells using a threshold related to the maximum of the red, green and blue intensities in Hue-Saturation-Value. Field measurements showed this corresponded to the location where the watertable was within 2 cm of the beachface surface. Timestacks, time series of pixels extracted from cross-shore transects in the video imagery, were used to determine the location of the shoreline by manually digitizing the maximum run-up and minimum run-down location for each swash cycle, and averaging the result. In our test data set of 14 days covering a range of wave and rainfall conditions, we found 6 days when the elevation difference between the wet-dry boundary and the shoreline remained approximately constant during the tidal cycle. For these days, the wet-dry boundary corresponded to the upper limit of the swash zone. On the other 8 days, the wet-dry boundary and the shoreline decoupled with falling tide, leading to elevation differences of up to 2.5 m at low tide. Elevation differences between the GWSL and the shoreline at low-tide were particularly large when the cumulative rainfall in the preceding month was greater than 200 mm. This research shows that the wet-dry boundary (such as often used in video shoreline-finding algorithms) is related to groundwater seepage on low-sloped, medium to fine sand beaches such as Ngaranui Beach (mean grain size~0.27 mm, beach slope ~1:70) and may not be a good indicator of the position of the shoreline

The effects of tides on swash statistics on an intermediate beach

Swash hydrodynamics were investigated on an intermediate beach using runup data obtained from video images. Under mild, near-constant, offshore wave conditions, the presence of a sandbar and the tidally controlled water depth over its crest determined whether most of the incoming waves broke before reaching the shoreline. This forced a change in the pattern of wave energy dissipation across the surf zone between low and high tide, which was reflected by changes to swash on time scales of a few hours. Significant runup height (Rs, defined as 4 times the standard deviation of the waterline time series), was found to vary by a factor of 2 between low tide, when most of the waves were breaking over the sandbar (Rs/Hs ≈ 1.5, where Hs is the offshore significant wave height) and high tide, when the waves were barely breaking (Rs/Hs ≈ 2.7). The increase in wave energy dissipation during low tide was also associated with changes in swash maxima distribution, a decrease in mean swash period, and increasing energy at infragravity frequencies. Bispectral analysis suggested that this infragravity modulation might have been connected with the presence of secondary waves

The use of imaging systems to monitor shoreline dynamics

The development of imaging systems is nowadays established as one of the most powerful and reliable tools for monitoring beach morphodynamics. Two different techniques for shoreline detection are presented here and, in one case, applied to the study of beach width oscillations on a sandy beach (Pauanui Beach, New Zealand). Results indicate that images can provide datasets whose length and sample interval are accurate enough to resolve inter-annual and seasonal oscillations, and long-term trends. Similarly, imaging systems can be extremely useful in determining the statistics of rip current occurrence. Further improvements in accuracy and reliability are expected with the recent introduction of digital systems

Detecting nonlinearity in run-up on a natural beach

International audienceNatural geophysical timeseries bear the signature of a number of complex, possibly inseparable, and generally unknown combination of linear, stable non-linear and chaotic processes. Quantifying the relative contribution of, in particular, the non-linear components will allow improved modelling and prediction of natural systems, or at least define some limitations on predictability. However, difficulties arise; for example, in cases where the series are naturally cyclic (e.g. water waves), it is most unclear how this cyclic behaviour impacts on the techniques commonly used to detect the nonlinear behaviour in other fields. Here a non-linear autoregressive forecasting technique which has had success in demonstrating nonlinearity in non-cyclical geophysical timeseries, is applied to a timeseries generated by videoing the waterline on a natural beach (run-up), which has some irregular oscillatory behaviour that is in part induced by the incoming wave field. In such cases, the deterministic shape of each run-up cycle has a strong influence on forecasting results, causing questionable results at small (within a cycle) prediction distances. However, the technique can clearly differentiate between random surrogate series and natural timeseries at larger prediction distances (greater than one cycle). Therefore it was possible to clearly identify nonlinearity in the relationship between observed run-up cycles in that a local autoregressive model was more adept at predicting run-up cycles than a global one. Results suggest that despite forcing from waves impacting on the beach, each run-up cycle evolves somewhat independently, depending on a non-linear interaction with previous run-up cycles. More generally, a key outcome of the study is that oscillatory data provide a similar challenge to differentiating chaotic signals from correlated noise in that the deterministic shape causes an additional source of autocorrelation which in turn influences the predictability at small forecasting distances

Unidimensional and Multidimensional Methods for Recurrence Quantification Analysis with crqa

Recurrence quantification analysis is a widely used method for characterizing patterns in time series. This article presents a comprehensive survey for conducting a wide range of recurrence based analyses to quantify the dynamical structure of single and multivariate time series and capture coupling properties underlying leader-follower relationships. The basics of recurrence quantification analysis (RQA) and all its variants are formally introduced step-by-step from the simplest auto recurrence to the most advanced multivariate case. Importantly, we show how such RQA methods can be deployed under a single computational framework in R using a substantially renewed version of our crqa 2.0 package. This package includes implementations of several recent advances in recurrence based analysis, among them applications to multivariate data and improved entropy calculations for categorical data. We show concrete applications of our package to example data, together with a detailed description of its functions and some guidelines on their usage

CARACTERÍSTICAS CLÍNICO EPIDEMIOLÓGICAS DE LA ENFERMEDAD DE PARKINSON EN UN HOSPITAL NACIONAL DE LA SIERRA PERUANA: CLINICAL EPIDEMIOLOGICAL CHARACTERISTICS OF PARKINSON'S DISEASE IN A NATIONAL HOSPITAL OF THE PERUVIAN HIGHLANDS

Objective: To determine the main epidemiological and clinical characteristics of Parkinson's disease at the National Hospital "Ramiro Prialé Priale" in Huancayo. Methods: Observational, descriptive retrospective study of a serie of cases. 84 patients were studied between 2015 and 2017, treated in the outpatient clinic or hospitalization of Neurology and Internal Medicine, for which their medical records were reviewed, the sampling was non-probabilistic of the census type selected by the investigator's judgment. Results: The average age was 72.93 years, the male gender prevailed (58.3%), the degree of university education (50%) and the origin of Huancayo (77.4%). Decompensated arterial hypertension was the reason for hospitalization (19.1%), disease time ranged between 1-7 years (57.1%) and tremor at rest and bradykinesia was the most frequent motor symptom (23.8%) In non-motor symptoms, 38.1% had sleep disorders, 21.4% family history of Parkinson's disease and the most associated comorbidities were: depression (48.8%) and insomnia (41.7%). Conclusion: Parkinson's disease is a frequent pathology in older adults and males; The predominant motor symptom is resting tremor and bradykinesia, and the associated neuropsychiatric comorbidities are depression and insomnia.Objetivo: Determinar las principales características epidemiológicas y clínicas de la enfermedad de Parkinson en el Hospital Nacional “Ramiro Prialé Priale” de Huancayo. Métodos: Estudio observacional, descriptivo tipo retrospectivo de una serie de casos. Se estudió 84 pacientes entre los años 2015 y 2017, atendidos en la consulta externa u hospitalización de Neurología y Medicina interna, para ello se revisó sus historias clínicas, el muestreo fue no probabilístico de tipo censal seleccionados por juicio del investigador. Resultados: El promedio de edad fue 72,93 años, predominó el género masculino (58,3%), el grado de instrucción universitario (50%) y la procedencia de Huancayo (77,4%). La hipertensión arterial descompensada fue el motivo de hospitalización (19,1%), el tiempo de enfermedad tuvo un rango de 1-7 años (57,1%) y el temblor de reposo y bradicinesia fue el síntoma motor más frecuente (23,8%). En los síntomas no motores, 38,1% tuvieron alteraciones del sueño, 21,4% antecedentes familiares de enfermedad de Parkinson y las comorbilidades más asociadas fueron: depresión (48,8%) e insomnio (41,7%). Conclusión: La enfermedad de Parkinson es una patología frecuente en adultos mayores y en el sexo masculino; el síntoma motor que predomina es el temblor de reposo y bradicinesia, y las comorbilidades neuropsiquiátricas asociadas son la depresión e insomnio

Field observations of swash zone infragravity motions and beach cusp evolution

Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 110 (2005): C02018, doi:10.1029/2004JC002485.Fluid flows consistent with low-mode edge waves were evident in video observations of swash motions during a field experiment in which beach cusps developed on an initially smooth beach. As beach cusps grew, energy lying along low-mode dispersion curves increased. The most energetic edge-wave propagation direction changed from upcoast to downcoast as the orientation of the cusp horns rotated. These observations suggest a coupling between morphodynamics and hydrodynamics, and are evidence that beach cusp evolution might control low-mode edge wave dynamics.This work was performed while Y. C. was a visiting scientist at NIWA funded by UPC. Y. C. thanks NIWA for its kind hospitality. G. C. is supported by the (New Zealand) Foundation for Research, Science and Technology (contract C01X0401). S. E. was supported by ONR, NSF, and ARO

The patient-physician relationship in the face of oncological disease: A review of literature on the emotional and psychological reactions of patients and physician

The physician-patient relationship is daily destabilized by emotional reactions and psychic defenses that cancer arises in the two partners. Continued scientific and technological progresses which were reached by medicine in recent years, and particularly oncologic clinical discoveries, increased the chance of not only survival but also healing. Nevertheless, cancer diagnosis is still a hard existential text that destabilizes everyday life, all the psychic and relational balance, inevitably causing a psychological and social change not only in the patient who is affected but also into the wide social network around him (family, friends, doctors, healthcare team). The aim of this review is to understand how problems, feelings, emotions, distresses or defense mechanisms could garble the relation and the communication dynamics between physician and patients and then prejudicing the efficacy of oncologic therapeutic compliance. Pubmed and Scopus were searched, using strings related to "cancer", "physician-patient relations", burn-out", "compliance", and "communication", identifying literature published from 2000 to January 2015. Extracted papers were assessed for their relevance (10 of 412 papers initially reviewed). Results indicate that a good and empathetic relationship between physician and patient were related to good therapeutic adherence. In particular, a good physician-patient relation maximizes the impact of clinical therapies and reduces psychophysical implications

Gender and the systemic hypertension-snoring association: a questionnaire-based case-control study.

Since the role of gender in the association between hypertension and snoring is unknown, we studied it while accounting for age and body mass index (BMI) as confounding variables. A questionnaire on snoring was administered to 90 hypertensive (HT) subjects (45 men and 45 women) and to 90 normotensive (NT) subjects matched for gender, age and BMI. As expected, snoring was more commonly reported by men than by women, but no significant difference was found between HT and NT men, irrespective of age. Conversely, heavy snoring was more frequently reported by HT than NT women; habitual snoring was more common among young (age50 years) HT than NT women; and heavy snoring was more common among older (age50 years) HT than NT women. These data suggest an effect of gender on the hypertension-snoring association: in men, snoring may be accounted for by age and BMI whether or not hypertension is present, whereas in women the natural history of snoring appears different and more severe in HT than in NT. Although the mechanism(s) responsible for the differences between men and women are obscure at present, gender may be an important variable in the systemic hypertension-snoring association