Model term selection for spatio-temporal system identification using mutual information

A new mutual information based algorithm is introduced for term selection in spatio-temporal models. A generalised cross validation procedure is also introduced for model length determination and examples based on cellular automata, coupled map lattice and partial differential equations are described

Biophysical modelling of a drosophila photoreceptor

It remains unclear how visual information is co-processed by different layers of neurons in the retina. In particular, relatively little is known how retina translates vast environmental light changes into neural responses of limited range. We began examining this question in a bottom-up way in a relatively simple °y eye. To gain understanding of how complex bio-molecular interactions govern the conversion of light input into voltage output (phototransduction), we are building a biophysical model of the Drosophila R1-R6 photoreceptor. Our model, which relates molecular dynamics of the underlying biochemical reactions to external light input, attempts to capture the molecular dynamics of phototransduction gain control in a quantitative way

Recovery of missing data in correlated smart grid datasets

We study the recovery of missing data from multiple smart grid datasets within a matrix completion framework. The datasets contain the electrical magnitudes required for monitoring and control of the electricity distribution system. Each dataset is described by a low rank matrix. Different datasets are correlated as a result of containing measurements of different physical magnitudes generated by the same distribution system. To assess the validity of matrix completion techniques in the recovery of missing data, we characterize the fundamental limits when two correlated datasets are jointly recovered. We then proceed to evaluate the performance of Singular Value Thresholding (SVT) and Bayesian SVT (BSVT) in this setting. We show that BSVT outperforms SVT by simulating the recovery for different correlated datasets. The performance of BSVT displays the tradeoff behaviour described by the fundamental limit, which suggests that BSVT exploits the correlation between the datasets in an efficient manner

A nonlinear land use regression approach for modelling NO2 concentrations in urban areas—Using data from low-cost sensors and diffusion tubes

Land Use Regression (LUR) based on multiple linear regression model is one of the techniques used most frequently for modelling the spatial variability of air pollution and assessing exposure in urban areas. In this paper, a nonlinear generalised additive model is proposed for LUR and its performance is compared to a linear model in Sheffield, UK for the year 2019. Pollution models were estimated using NO2 measurements obtained from 188 diffusion tubes and 40 low-cost sensors. Performance of the models was assessed by calculating several statistical metrics including correlation coefficient (R) and root mean square error (RMSE). High resolution (100 m × 100 m) maps demonstrated higher levels of NO2 in the city centre, eastern side of the city and on major roads. The results showed that the nonlinear model outperformed the linear counterpart and that the model estimated using NO2 data from diffusion tubes outperformed the models using data from low-cost sensors or both low-cost sensors and diffusion tubes. The proposed method provides a basis for further application of advanced nonlinear modelling approaches to constructing LUR models in urban areas which enable quantifying small scale variability in pollution levels

Analysis of air pollution in urban areas with Airviro dispersion model—A case study in the city of Sheffield, United Kingdom

Two air pollutants, oxides of nitrogen (NOx) and particulate matter (PM10), are monitored and modelled employing Airviro air quality dispersion modelling system in Sheffield, United Kingdom. The aim is to determine the most significant emission sources and their spatial variability. NOx emissions (ton/year) from road traffic, point and area sources for the year 2017 were 5370, 6774, and 2425, whereas those of PM10 (ton/year) were 345, 1449, and 281, respectively, which are part of the emission database. The results showed three hotspots of NOx, namely the Sheffield City Centre, Darnall and Tinsley Roundabout (M1 J34S). High PM10 concentrations were shown mainly between Sheffield Forgemasters International (a heavy engineering steel company) and Meadowhall Shopping Centre. Several emission scenarios were tested, which showed that NOx concentrations were mainly controlled by road traffic, whereas PM10 concentrations were controlled by point sources. Spatiotemporal variability and public exposure to air pollution were analysed. NOx concentration was greater than 52 µg/m3 in about 8 km2 area, where more than 66 thousand people lived. Models validated by observations can be used to fill in spatiotemporal gaps in measured data. The approach used presents spatiotemporal situation awareness maps that could be used for decision making and improving the urban infrastructure

Report of the International Society of Hypertension (ISH) Hypertension Teaching Seminar organized by the ISH Africa Regional Advisory Group: Maputo, Mozambique, 2016

The International Society of Hypertension (ISH), in fulfilment of its mission of promoting hypertension control and prevention and also of advancing knowledge globally, organizes hypertension teaching seminars or ‘summer schools’ worldwide through the ISH Regional Advisory Groups. In Africa, seven of such seminars have been organized. This is a report of the eighth seminar held in Maputo, Mozambique, April, 2016. The seminar was attended by over 65 participants from 11 African countries. The Faculty consisted of 11 international hypertension experts. The eighth African hypertension seminar was a great success as confirmed by a pre- and post-test questionnaire

Improvement of Enzymatic Hydrolysis of Steam-exploded Wheat Straw by Simultaneous Glucose and Xylose Liberation

This work aimed at enhancing enzymatic hydrolysis of steam-exploded wheat-straw by investigating factors affecting hydrolysis. A multi-objective optimization of glucose and xylose release was performed using Celluclast 1.5L and Ultraflo-L mixtures with maximal values of 20 for enzyme/substrate ratio, 72 h for reaction time, 50 °C for temperature and 5.0 for pH. The highest sugar yields obtained were 18.9 ± 0.4 g/100gDM for glucose and 4.7 ± 0.2 g/100gDM for xylose. The addition of Ultraflo-L could increase the liberation of xylose, but has no pronounced effect on glucose release. The effect of β-glucosidase addition to the Ultraflo+Celluclast mixture for improving sugar yield was also studied. The β-glucosidase supplementation increased the production by approximately 29.9 % for glucose and 5.9 % for xylose, when a β-glucosidase loading of 10 % gβ-glucosidase/gcellulose was used

Coastal altimetry products in the strait of Gibraltar

This paper analyzes the availability and accuracy of coastal altimetry sea level products in the Strait of Gibraltar. All possible repeats of two sections of the Envisat and AltiKa ground-tracks were used in the eastern and western portions of the strait. For Envisat, along-track sea level anomalies (SLAs) at 18-Hz posting rate were computed using ranges from two sources, namely, the official SGDRs and the outputs of a coastal waveform retracker, the ALES retracker; in addition, SLAs at 1 Hz were obtained from CTOH, France. For AltiKa, along-track SLA at 40 Hz was also computed both from SGDR and ALES ranges. The quality of these altimeter products was validated using two tide gauges located on the southern coast of Spain. We observed an improvement of about 20% in the accuracy of the Envisat SLAs from ALES compared to the standard (SGDR) and the reprocessed CTOH data sets. AltiKa shows higher accuracy, with no significant differences between SGDR and ALES

La regeneración del pinsapar en la sierra de Grazalema. I: análisis de la fase de plántula

Se estudia la dinámica de la regeneración del pinsapar en la Sierra de Grazalema. Previamente se ha llevado a cabo una diferenciación del conjunto del pinsapar a partir de la información disponible de inventarios, fotointerpretación, bibliografía y datos de campo, dando como resultados cuatro tipos estructurales: Pinsapar puro estructurado, Pinsapar puro latizal-fustal, Quejigal con pinsapos y Encinar con pinsapos. En este estudio, el análisis del proceso de regeneración se centra en el regenerado en estado de plántula, donde la mortalidad puede tener una incidencia enorme debida especialmente a la sequía estival propia del ámbito mediterráneo. Se ha establecido un dispositivo de muestreo sistemático en los cuatro estratos, medido una vez finalizada la germinación de semillas del año y después del verano. Con los datos obtenidos se ha estudiado tanto la incorporación, como la mortalidad de nuevas plántulas. Se han encontrado diferencias significativas entre los estratos de pinsapar puro y los mixtos, tanto en incorporación de nuevas plántulas como en mortalidad. También existen diferencias dentro de los dos estratos de pinsapar pur

La regeneración del pinsapar en la sierra de Grazalema. II: estructura y dinámica del regenerado consolidado en el pinsapar puro

En los tipos estructurales de pinsapar puro, se estudia la dinámica y la estructura del regenerado consolidado (plantas de más de un año de edad que no alcanzan las dimensiones de los pies menores, es decir, menos de 1,5 m de altura). El motivo de separar este grupo del de plántulas menores de un año, estriba en las diferentes posibilidades de supervivencia de uno y otro estado ya que en el regenerado consolidado va a depender en mayor medida del grado de competencia al que se vea sometido que de las condiciones locales del medio en que se asienta. El análisis de la distribución de alturas por clases muestra importantes diferencias significativas entre ambos estratos de pinsapar puro, para la clase < 15 cm pero no para las demás clases. Se ha analizado la evolución de la densidad del regenerado por clases de altura desde la fase de plántula hasta la de pie menor, obteniendo una gráfica descendente similar en ambos estratos con una caída brusca inexplicada en la clase de 100 a 150 cm, seguida de una subida en la clase de pies menores atribuida al estancamiento en el crecimiento en altura. El estudio de la relación altura edad demuestra que ésta es significativa, para el regenerado, pero no para los pies menores, indicando así que este grupo se compone de árboles dominados de numerosas y muy distintas edades. El regenerado consolidado constituye una reserva de regeneración a la espera, cuyos individuos aprovecharían las perturbaciones en la estructura para prosperar. Puede decirse que en las circunstancias actuales y frente a perturbaciones no catastróficas, la persistencia del pinsapar está asegurad