Search results for " data"
showing 10 items of 7516 documents
speedglm: Fitting Linear and Generalized Linear Models to large data sets.
2009
This is an R packge to fit (generalized) linear models to large data sets. For data loaded in R memory the fitting is usually fast, especially if R is linked against an optimized BLAS. For data sets of size greater of R memory, the fitting is made by an updating algorithm
Interaction of glutamic-acid-rich proteins with the cGMP signalling pathway in rod photoreceptors.
1999
The assembly of signalling molecules into macromolecular complexes (transducisomes) provides specificity, sensitivity and speed in intracellular signalling pathways. Rod photoreceptors in the eye contain an unusual set of glutamic-acid-rich proteins (GARPs) of unknown function. GARPs exist as two soluble forms, GARP1 and GARP2, and as a large cytoplasmic domain (GARP' part) of the beta-subunit of the cyclic GMP-gated channel. Here we identify GARPs as multivalent proteins that interact with the key players of cGMP signalling, phosphodiesterase and guanylate cyclase, and with a retina-specific ATP-binding cassette transporter (ABCR), through four, short, repetitive sequences. In electron mic…
Bayesian estimation of partial population continuity using ancient DNA and spatially explicit simulations.
2017
Abstract The retrieval of ancient DNA from osteological material provides direct evidence of human genetic diversity in the past. Ancient DNA samples are often used to investigate whether there was population continuity in the settlement history of an area. Methods based on the serial coalescent algorithm have been developed to test whether the population continuity hypothesis can be statistically rejected by analysing DNA samples from the same region but of different ages. Rejection of this hypothesis is indicative of a large genetic shift, possibly due to immigration occurring between two sampling times. However, this approach is only able to reject a model of full continuity model (a tot…
Recent Activity and Kinematics of the Bounding Faults of the Catanzaro Trough (Central Calabria, Italy): New Morphotectonic, Geodetic and Seismologic…
2021
A multidisciplinary work integrating structural, geodetic and seismological data was performed in the Catanzaro Trough (central Calabria, Italy) to define the seismotectonic setting of this area. The Catanzaro Trough is a structural depression transversal to the Calabrian Arc, lying in-between two longitudinal grabens: the Crati Basin to the north and the Mesima Basin to the south. The investigated area experienced some of the strongest historical earthquakes of Italy, whose seismogenic sources are still not well defined. We investigated and mapped the major WSW–ENE to WNW–ESE trending normal-oblique Lamezia-Catanzaro Fault System, bounding to the north the Catanzaro Trough. Morphotectonic …
Volcanic Lakes in Africa: The VOLADA_Africa 2.0 Database, and Implications for Volcanic Hazard
2021
Volcanic lakes pose specific hazards inherent to the presence of water: phreatic and phreatomagmatic eruptions, lahars, limnic gas bursts and dispersion of brines in the hydrological network. Here we introduce the updated, interactive and open-access database for African volcanic lakes, country by country. The previous database VOLADA (VOlcanic LAke DAta Base, Rouwet et al., Journal of Volcanology and Geothermal Research, 2014, 272, 78–97) reported 96 volcanic lakes for Africa. This number is now revised and established at 220, converting VOLADA_Africa 2.0 in the most comprehensive resource for African volcanic lakes: 81 in Uganda, 37 in Kenya, 33 in Cameroon, 28 in Madagascar, 19 in Ethiop…
Can Dasymetric Mapping Significantly Improve Population Data Reallocation in a Dense Urban Area?
2016
The issue of reallocating population figures from a set of geographical units onto another set of units has received a great deal of attention in the literature. Every other day, a new algorithm is proposed, claiming that it outperforms competitor procedures. Unfortunately, when the new (usually more complex) methods are applied to a new data set, the improvements attained are sometimes just marginal. The relationship cost-effectiveness of the solutions is case-dependent. The majority of studies have focused on large areas with heterogeneous population density distributions. The general conclusion is that as a rule more sophisticated methods are worth the effort. It could be argued, however…
Multiple positive normalized solutions for nonlinear Schrödinger systems
2018
We consider the existence of multiple positive solutions to the nonlinear Schr\"odinger systems sets on $H^1(\mathbb{R}^N) \times H^1(\mathbb{R}^N)$, \[ \left\{ \begin{aligned} -\Delta u_1 &= \lambda_1 u_1 + \mu_1 |u_1|^{p_1 -2}u_1 + \beta r_1 |u_1|^{r_1-2} u_1|u_2|^{r_2}, -\Delta u_2 &= \lambda_2 u_2 + \mu_2 |u_2|^{p_2 -2}u_2 + \beta r_2 |u_1|^{r_1} |u_2|^{r_2 -2} u_2, \end{aligned} \right. \] under the constraint \[ \int_{\mathbb{R}^N}|u_1|^2 \, dx = a_1,\quad \int_{\mathbb{R}^N}|u_2|^2 \, dx = a_2. \] Here $a_1, a_2 >0$ are prescribed, $\mu_1, \mu_2, \beta>0$, and the frequencies $\lambda_1, \lambda_2$ are unknown and will appear as Lagrange multipliers. Two cases are studied, the first …
Habitat type and island identity as drivers of community assembly in an archipelago
2020
Aim: Ecoinformatics offer new opportunity to test islands as biogeographic and eco- logical models. In this paper we predicted three hypotheses: (1) plot-based data issu- ing from vegetation surveys can be used to predict Island Species-Area Relationships (ISARs) or island similarity; (2) the habitat area is an independent predictor of species richness patterns within island; (3) species richness and composition are more de- pendent on habitat type than island identity in land-bridge islands. Area: Tuscan Archipelago, Italy. Methods: We assembled a database of all the vegetation plots available for the archi- pelago. For the first hypothesis we calculated ISARs, using Arrhenius model, and B…
Soil geography and diversity of the European biogeographical regions
2013
For decades, soil geography has beenmainly a qualitative and descriptive discipline. There are nowtechnologies and mathematical tools available that allow formalizing soil geography in more quantitative terms. In this paper, the distribution and diversity of the soils of Europe are analyzed using GIS tools and pedodiversity algorithms. Soil data were taken from the European Soil Database (V2.0) and computed within the spatial framework of the Biogeographical Regions of Europe (BGRE) as defined by the European Environmental Agency (EEA) on the basis of climate and vegetation. The results obtained show the soil assemblages, including dominant soils and endemic and non-endemic soil minorities,…
A comparison of different methods for speleothem age modelling
2012
Abstract Speleothems, such as stalagmites and flowstones, can be dated with unprecedented precision in the range of the last 650,000 a by the 230Th/U-method, which is considered as one of their major advantages as climate archives. However, a standard approach for the construction of speleothem age models and the estimation of the corresponding uncertainty has not been established yet. Here we apply five age modelling approaches ( StalAge , OxCal, a finite positive growth rate model and two spline-based models) to a synthetic speleothem growth model and two natural samples. All data sets contain problematic features such as outliers, age inversions, large and abrupt changes in growth rate a…