Highlights ► The mechanical behavior of a spring-like AFO was studied in 10 patients. ► The spring-like AFO did not augment ankle push-off. ► The spring-like AFO took over part of the ankle work. ► ...The energy cost of walking was reduced with the spring-like AFO.
A cellular automata model is used to analyze the effects of groundwater levels and sediment supply on aeolian dune development occurring on sand flats close to inlets. The model considers, in a ...schematized and probabilistic way, aeolian transport processes, groundwater influence, vegetation development, and combined effects of waves and tides that can both erode and accrete the sand flat. Next to three idealized cases, a sand flat adjoining the barrier island of Texel, the Netherlands, was chosen as a case study. Elevation data from 18 annual LIDAR surveys was used to characterize sand flat and dune development. Additionally, a field survey was carried out to map the spatial variation in capillary fringe depth across the sand flat. Results show that for high groundwater situations, sediment supply became limited inducing formation of Coppice-like dunes, even though aeolian losses were regularly replenished by marine import during sand flat flooding. Long dune rows developed for high sediment supply scenarios which occurred for deep groundwater levels. Furthermore, a threshold depth appears to exist at which the groundwater level starts to affect dune development on the inlet sand flat. The threshold can vary spatially depending on external conditions such as topography. On sand flats close to inlets, groundwater is capable of introducing spatial variability in dune growth, which is consistent with dune development patterns found on the Texel sand flat.
Micromagnetic tomography (MMT) is a technique that combines X‐ray micro computed tomography and scanning magnetometry data to obtain information about the magnetic potential of individual grains ...embedded in a sample. Recovering magnetic signals of individual grains in natural and synthetic samples provides a new pathway to study the remanent magnetization that carries information about the ancient geomagnetic field and is the basis of all paleomagnetic studies. MMT infers the magnetic potential of individual grains by numerical inversion of surface magnetic measurements using spherical harmonic expansions. The magnetic potential of individual particles in principle is uniquely determined by MMT, not only by the dipole approximation, but also more complex, higher order, multipole moments. Here, we show that such complex magnetic information together with both particle shape and mineral properties severely constrains the internal magnetization structure of an individual grain. To this end, we apply a three dimensional micromagnetic model to predict the multipole signal from magnetization states of different local energy minima. We show that for certain grains it is even possible to uniquely infer the magnetic configuration from the inverted magnetic multipole moments. This result is crucial to discriminate single‐domain particles from grains in more complex configurations such as multi‐domain or vortex states. As a consequence, our investigation proves that by MMT it is feasible to select statistical ensembles of magnetic grains based on their magnetization states, which opens new possibilities to identify and characterize stable paleomagnetic recorders in natural samples.
Plain Language Summary
Paleomagnetic studies obtain information about the ancient magnetic field of the Earth (MFE) by analyzing the magnetic signal recorded in natural (e.g., volcanic) rocks. Natural rocks carry tiny magnetic mineral grains, usually of micrometer sizes, which can store both the intensity and direction of the MFE at the time of the rock formation. However, grains have a variety of physical properties, such as geometry and chemical composition, in a sample, thus only a proportion of the grains store a stable, and hence reliable, magnetic signal. The technique of micromagnetic tomography (MMT) has recently been developed to study the magnetic signal of individual grains in rock samples using advanced microscopy and tomography. This has allowed to statistically select grains with similar properties and “good” signals, enabling to obtain more accurate estimates of the MFE. In this work, we build a method to both construct computational models of individual grains and infer their internal magnetic structure using MMT data. For instance, in the range of grain sizes studied here, the magnetic field within a grain usually forms vortex patterns which grant the grain a characteristic stability. This result provides extra information to classify grains and refine the precision of the MFE calculations.
Key Points
The internal magnetic state of individual grains may be inferred from higher order magnetic moments produced by micromagnetic tomography
This is done by comparing these moments to predicted multipole signals from local energy minima obtained from micromagnetic simulations
Our results are crucial to discriminate between reliable and unreliable paleomagnetic recorders based on their internal domain structure
Aim
To determine development curves of communication and social interaction from childhood into adulthood for individuals with cerebral palsy (CP).
Method
This Pediatric Rehabilitation Research in ...the Netherlands (PERRIN)‐DECADE study longitudinally assessed 421 individuals with CP, aged from 1 to 20 years at baseline, after 13 years (n=121 at follow‐up). Communication and social interactions were assessed using the Vineland Adaptive Behavior Scales. We estimated the average maximum performance limit (level) and age at which 90% of the limit was reached (age90) using nonlinear mixed‐effects modeling.
Results
One‐hundred individuals without intellectual disability were aged 21 to 34 years at follow‐up (39 females, 61 males) (mean age SD 28y 5mo 3y 11mo). Limits of individuals without intellectual disability, regardless of Gross Motor Function Classification System (GMFCS) level, approached the maximum score and were significantly higher than those of individuals with intellectual disability. Ages90 ranged between 3 and 4 years for receptive communication, 6 and 7 years for expressive communication and interrelationships, 12 and 16 years for written communication, 13 and 16 years for play and leisure, and 14 and 16 years for coping. Twenty‐one individuals with intellectual disability were between 21 and 27 years at follow‐up (8 females, 13 males) (mean age SD 24y 7mo 1y 8mo). Individuals with intellectual disability in GMFCS level V showed the least favourable development, but variation between individuals with intellectual disability was large.
Interpretation
Individuals with CP and without intellectual disability show developmental curves of communication and social interactions similar to typically developing individuals, regardless of their level of motor function. Those with intellectual disability reach lower performance levels and vary largely in individual development.
What this paper adds
Communication and social interactions in individuals with cerebral palsy without intellectual disability develop similarly to typically developing individuals.
Communication and social interactions of individuals with intellectual disability develop less favourably and show large variation.
Resumen
Curvas de desarrollo de comunicación e interacción social en niños con parálisis cerebral
Objetivo
Determinar las curvas de desarrollo de la comunicación y la interacción social desde la infancia hasta la edad adulta para las personas con parálisis cerebral (PC).
Método
Esta Investigación de Rehabilitación Pediátrica en el Estudio de los Países Bajos (PERRIN)‐DECADE evaluó longitudinalmente 421 individuos con PC, de 1 a 20 años en el inicio, después de 13 años (n=121 en el seguimiento). La comunicación y las interacciones sociales se evaluaron utilizando la Escala de comportamiento adaptativo de Vineland. Estimamos el límite promedio de rendimiento máximo (nivel) y la edad a la que se alcanzó el 90% del límite (edad90) utilizando un modelo no lineal de efectos mixtos.
Resultados
Cien individuos sin discapacidad intelectual tenían entre 21 y 34 años en el seguimiento (39 mujeres, 61 varones; edad media DS 28 y 5 meses 3 años y 11meses). Los límites de las personas sin discapacidad intelectual, independientemente del nivel del Sistema de Clasificación de la Función Motora Gruesa (GMFCS), se acercaron a la puntuación máxima y fueron significativamente superiores a los de personas con discapacidad intelectual. Edad 90s entre 3 y 4 años para la comunicación receptiva, 6 y 7 años para la comunicación expresiva y las interrelaciones, 12 y 16 años para la comunicación escrita, 13 y 16 años por juego y ocio, y 14 y 16 años por sobrellevarlo. Veintiún individuos con discapacidad intelectual tenían entre 21 y 27 años en seguimiento (8 mujeres, 13 hombres; edad media DS 24 años y 7 meses 1 año y 8 meses). Las personas con discapacidad intelectual en el nivel V de GMFCS mostraron el desarrollo menos favorable, pero la variación entre las personas con discapacidad intelectual fue grande.
Interpretación
Las personas con PC sin discapacidad intelectual muestran curvas de desarrollo de comunicación e interacciones sociales similares a las personas con desarrollo típico, no considerando su nivel de función motora. Las personas con PC y discapacidad intelectual alcanzan niveles de rendimiento más bajos y varían en gran medida en el desarrollo individual.
Resumo
Curvas de desenvolvimento da comunicação e interação social em crianças com paralisia cerebral
Objetivo
Determinar as curvas de desenvolvimento e interação social da infância para a adolescência para indivíduos com paralisia cerebral (PC).
Método
Este estudo Europeu de Reabilitação Pediátrica na Holanda (PERRIN)‐DECADE avaliou longitudinalmente 421 indivíduos com PC, com idades de 1 a 20 anos na linha de base, após 13 anos, (n=121 no acompanhamento). A comunicação e interação social foram avaliadas usando as Escalas Vineland de Compartamento Adaptativo. Estimamos o limite máximo de desempenho médio (nível) e idade em que 90% do limite foi atingido (idade90) usando modelos não‐lineares de efeitos mistos.
Resultados
Cem indivíduos sem deficiência intelectual com idades entre 21 e 34 anos no acompanhamento (39 do sexo feminino, 61 do sexo masculino; média de idade DP 28a 5m 3a 11m). Os limites de indivíuduos sem deficiência intelectual, independente do nível do Sistema de Classificação da Função Motora Grossa (GMFCS), se aproximou da pontuação maxima e foram significativamente maiores do que os valores de indivíduos com deficiência intelectual. A idade 90s variou entre 3 e 4 anos para comunicação receptiva, 6 e 7 anos para comunicação expressiva e intercomunicações, 12 e 16 anos para comunicação escrita, 12 e 16 years para brincadeiras e lazer, e 14 e 16 anos para adaptabilidade. Vinte e um indivíduos com deficiência intelectual estavam entre 21 e 27 anos no acompanhamento (8 do sexo feminino, 13 do sexo masculino; média de idade DP 24a 7m 1a 8m). Indivíduos com deficiência intelectual no nível GMFCS V mostraram o desenvolvimento menos favorável, mas a variação entre indivíduos com deficiência intelectual foi grande.
Interpretação
Indivíduos com PC com e sem deficiência intelectual mostram curvas desenvolvimentais de comunicação e interação social similares a indivíduos com desempenho típico, independente do nível de função motora. Aqueles com deficiência intelectual tiveram menores níveis de performance e variaram amplamente no desenvolvimento individual.
What this paper adds
Communication and social interactions in individuals with cerebral palsy without intellectual disability develop similarly to typically developing individuals.
Communication and social interactions of individuals with intellectual disability develop less favourably and show large variation.
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The outcome of paleointensity experiments largely depends on the rock‐magnetic properties of the samples. To assess the relation between volcanic emplacement processes and rock‐magnetic properties, ...we sampled a vertical transect in a ∼6 m thick inflated lava flow at Hawaii, emplaced in ∼588 AD. Its rock‐magnetic properties vary as function of distance from the flow top; the observations can be correlated to the typical cooling rate profile for such a flow. The top and to a lesser extent the bottom parts of the flow cooled faster and reveal a composition of ∼TM60 in which the magnetic remanence is carried by fine‐grained titanomagnetites, relatively rich in titanium, with associated low Curie and unblocking temperatures. The titanomagnetite in the slower cooled central part of the flow is unmixed into the magnetite and ülvospinel end‐members as evidenced by scanning electron microscope observation. The remanence is carried by coarse‐grained magnetite lamella (∼TM0) with high Curie and unblocking temperatures. The calibrated pseudo‐Thellier results that can be accepted yield an average paleointensity of 44.1 ± 2.4 μT. This is in good agreement with the paleointensity results obtained using the thermal IZZI‐Thellier technique (41.6 ± 7.4 μT) and a recently proposed record for Hawaii. We therefore suggest that the chance of obtaining a reliable paleointensity from a particular cooling unit can be increased by sampling lavas at multiple levels at different distances from the top of the flow combined with careful preliminary testing of the rock‐magnetic properties.
Key Points
Rock‐magnetic properties vary as function of depth in an inflated sheet flow
These variations govern the chance of success in paleointensity experiments
Calibrated pseudo‐Thellier is an important new paleointensity technique
SUMMARY
Absolute palaeointensities are notoriously hard to obtain, because conventional thermal Thellier palaeointensity experiments often have low success rates for volcanic samples. The thermal ...treatments necessary for these experiments potentially induce (magnetic) alteration in the samples, preventing a reliable palaeointensity estimate. These heating steps can be avoided by pseudo-Thellier measurements, where samples are demagnetized and remagnetized with alternating fields. However, pseudo-Thellier experiments intrinsically produce relative palaeointensities. Over the past years, attempts were made to calibrate pseudo-Thellier results into absolute palaeointensities for lavas by mapping laboratory induced anhysteretic remanent magnetizations (ARMs) to the thermally acquired natural remanent magnetizations (NRMs). Naturally occurring volcanic rocks, however, are assemblages of minerals differing in grain size, shape and chemistry. These different minerals all have their own characteristic mapping between ARMs and thermal NRMs. Here, we show that it is possible to find these characteristic mappings by unmixing the NRM demagnetization and the ARM acquisition curves into end-members, with an iterative method of non-negative matrix factorization. In turn, this end-member modelling approach (EMMA) allows for the calculation of absolute palaeointensities from pseudo-Thellier measurements. We tested our EMMA using a noise-free numerical data set, yielding a perfect reconstruction of the palaeointensities. When adding noise up to levels beyond what is expected in natural samples, the end-member model still produces the known palaeointensities well. In addition, we made a synthetic data set with natural volcanic samples from different volcanic edifices that were given a magnetization by heating and cooling them in a controlled magnetic field in the lab. The applied fields ranged between 10 and 70 µT. The average absolute difference between the calculated palaeointensity and the known lab field is around 10 µT for the models with 2–4 end-members, while the palaeointensity of almost all flows can be retrieved within a deviation of ±20 µT. The deviations between the palaeointensities and the known lab fields are almost Gaussian distributed around the expected values. Although the two data sets in our study show that there is potential for using this end-member modelling technique for finding absolute palaeointensities from pseudo-Thellier data, these synthetic data sets cannot be directly related to natural samples. Therefore, it is necessary to compile a data set of known palaeointensities from different volcanic sites that recently cooled in a known magnetic field to find the universal end-members in future studies.
Intraconal hybrid neurofibroma ‐ schwannoma of the orbit Verhelst, E.; Lauwers, N.; Siozopoulou, V. ...
Acta ophthalmologica (Oxford, England),
September 2017, 2017-09-00, 20170901, Letnik:
95, Številka:
S259
Journal Article
Recenzirano
Purpose
Among peripheral nerve sheet tumors, an orbital hybrid neurofibroma‐schwannoma has been described twice. We describe a third case of orbital tumor with features of both a neurofibroma and a ...schwannoma.
Methods
Case report. A 39 year old man presents with diplopia and decreased vision (0.6) in the left eye. He has a proptosis of 7 mm, with mechanical restriction of elevation and horizontal eye movements. MRI shows a well‐defined lesion (2,5 x 1,9 x 2,3 cm) in the superotemporal intraconal space, displacing the globe, optic nerve and superior and lateral rectus muscles. The tumor demonstrates heterogeneous contrast enhancement, and is diagnosed as a probable cavernous hemangioma. Through a transconjunctival approach a red‐blueish lesion was found with a thin capsule and without lateral adhesions. The tumor could be extracted in 2 parts and consisted of a yellow/white coherent soft mass.
Results
Patient had complete recovery of visual acuity, and only diplopia in extreme lateral gaze. The pathology revealed a tumor composed of small spindle cells arranged in fascicles. The cells showed no atypia and there was no mitotic activity. There were also less cellular areas with a myxoid component. At places we could recognize a fibrous capsule surrounding the tumor. The tumor cells were strongly and diffuse positive with S100. In a few enclosed axons there was focal reactivity with neurofilament. The image is that of a neural tumor with features of both a neurofibroma and a Schwannoma.
Conclusions
This is the third reported orbital hybrid neurofibroma‐schwannoma. Although this type of tumor elsewhere in the body is often associated with schwannomatosis and neurofibromatosis, our patient did not show signs of systemic involvement.
Coastal dunes form in many parts of the world the first flood defense line against the sea. To study effects of climate change on coastal dune evolution, we used a cellular model of dune, beach, and ...vegetation development. The model was calibrated and validated against field measurements of the Dutch coast, showing good performance for 10 year simulations. A sensitivity analysis showed that dune size and morphology are most sensitive to the rate of aeolian input and wave dissipation. Finally, 100 year climate change scenarios were run to establish the impacts of sea level rise and changes in vegetation growth rate on dune evolution. The results are in good agreement with conceptual models of dune evolution. Sea level rise largely determines the direction of dune evolution: the rate of rising controls whether dunes are able to preserve their height or sand volume while migrating landward. The effect of changing vegetation growth rates, resulting from climate change, is most manifest in dune response to large disturbances. If vegetation is removed halfway into the simulation, vegetation growth rate determines whether a foredune will revegetate and recover its height. Low vegetation growth rates result in mobile dunes that lose sand. The good agreement between observations and predictions indicates that the model successfully incorporates the suite of biogeomorphic and marine processes involved in dune building.
Key Points
Marine, aeolian, and biophysical processes are simulated in a coastal dune model
For moderate rates of sea level rise, dunes are able to retreat with preservation of height
A reduction in plant growth might induce a disproportionately large reduction in dune resilience
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