Search results for "Maxim"
showing 10 items of 1236 documents
L1-Penalized Censored Gaussian Graphical Model
2018
Graphical lasso is one of the most used estimators for inferring genetic networks. Despite its diffusion, there are several fields in applied research where the limits of detection of modern measurement technologies make the use of this estimator theoretically unfounded, even when the assumption of a multivariate Gaussian distribution is satisfied. Typical examples are data generated by polymerase chain reactions and flow cytometer. The combination of censoring and high-dimensionality make inference of the underlying genetic networks from these data very challenging. In this article, we propose an $\ell_1$-penalized Gaussian graphical model for censored data and derive two EM-like algorithm…
A heuristic, iterative algorithm for change-point detection in abrupt change models
2017
Change-point detection in abrupt change models is a very challenging research topic in many fields of both methodological and applied Statistics. Due to strong irregularities, discontinuity and non-smootheness, likelihood based procedures are awkward; for instance, usual optimization methods do not work, and grid search algorithms represent the most used approach for estimation. In this paper a heuristic, iterative algorithm for approximate maximum likelihood estimation is introduced for change-point detection in piecewise constant regression models. The algorithm is based on iterative fitting of simple linear models, and appears to extend easily to more general frameworks, such as models i…
Hippocampal hyperexcitability is modulated by microtubule-active agent: evidence from in vivo and in vitro epilepsy models in the rat
2016
The involvement of microtubule dynamics on bioelectric activity of neurons and neurotransmission represents a fascinating target of research in the context of neural excitability. It has been reported that alteration of microtubule cytoskeleton can lead to profound modifications of neural functioning, with a putative impact on hyperexcitability phenomena. Altogether, in the present study we pointed at exploring the outcomes of modulating the degree of microtubule polymerization in two electrophysiological epileptiform activity in the rat hippocampus. To this aim, we used in vivo Maximal Dentate Activation (MDA) and in vitro hippocampal epileptiform bursting activity (HEBA) paradigms to asse…
Sustainable Growth Rate: An Analysis Regarding the Most Traded Companies on the Bucharest Stock Exchange
2018
The concept of sustainable growth rate was originally developed by Robert C. Higgins. In the case of companies with given stable financial policies, it is considered to be the link between growth-return rate combinations that gives a balanced growth line. This indicates the possibilities for a company to grow without generating deficits or cash surpluses. Increased sales require more assets, which can be financed by new debt, external equity, and internal equity through retained earnings. The sustainable growth rate is the maximum rate at which company sales can increase without decreasing its financial resources. The aim of this paper is to determine if the last year most traded companies …
Rheological characterisation of cold bitumen emulsion slurries
2021
The performance of cold bitumen emulsion (CBE) mixtures is strongly linked to an optimised design of the binder blends and mastics. Types and dosages of bitumen, mineral additions and the workability must be characterised and optimised. This study aims at providing an approach for the fundamental characterisation of CBE materials using rotational viscometry. Firstly, a procedure for measuring the viscosity of CBE slurries using the Brookfield viscometer was investigated by comparing results obtained by using a traditional spindle geometry and a novel impeller engineered to avoid phase separation: the dual helical ribbon (DHR). Afterwards, the effect of mineral additions and bitumen emulsion…
Probabilistic cross-validation estimators for Gaussian process regression
2018
Gaussian Processes (GPs) are state-of-the-art tools for regression. Inference of GP hyperparameters is typically done by maximizing the marginal log-likelihood (ML). If the data truly follows the GP model, using the ML approach is optimal and computationally efficient. Unfortunately very often this is not case and suboptimal results are obtained in terms of prediction error. Alternative procedures such as cross-validation (CV) schemes are often employed instead, but they usually incur in high computational costs. We propose a probabilistic version of CV (PCV) based on two different model pieces in order to reduce the dependence on a specific model choice. PCV presents the benefits from both…
One repetition maximum bench press performance: A new approach for its evaluation in inexperienced males and females: A pilot study
2014
Summary The aim of this study was to evaluate a new method to perform the one repetition maximum (1RM) bench press test, by combining previously validated predictive and practical procedures. Eight young male and 7 females participants, with no previous experience of resistance training, performed a first set of repetitions to fatigue (RTF) with a workload corresponding to 1/3 of their body mass (BM) for a maximum of 25 repetitions. Following a 5-min recovery period, a second set of RTF was performed with a workload corresponding to 1/2 of participants’ BM. The number of repetitions performed in this set was then used to predict the workload to be used for the 1RM bench press test using May…
Demogenomic modeling of the timing and the processes of early European farmers differentiation
2020
AbstractThe precise genetic origins of the first Neolithic farming populations, as well as the processes and the timing of their differentiation, remain largely unknown. Based on demogenomic modeling of high-quality ancient genomes, we show that the early farmers of Anatolia and Europe emerged from a multiphase mixing of a Near Eastern population with a strongly bottlenecked Western hunter-gatherer population after the Last Glacial Maximum. Moreover, the population branch leading to the first farmers of Europe and Anatolia is characterized by a 2,500-year period of extreme genetic drift during its westward range expansion. Based on these findings, we derive a spatially explicit model of the…
Maximal subgroups and PST-groups
2013
A subgroup H of a group G is said r to permute with a subgroup K of G if HK is a subgroup of G. H is said to be permutable (resp. S-permutable) if it permutes with all the subgroups (resp. Sylow subgroups) of G. Finite groups in which permutability (resp. S-permutability) is a transitive relation are called PT-groups (resp. PST-groups). PT-, PST- and T-groups, or groups in which normality is transitive, have been extensively studied and characterised. Kaplan [Kaplan G., On T-groups, supersolvable groups, and maxmial subgroups, Arch. Math. (Basel), 2011, 96(1), 19-25)] presented some new characterisations of soluble T-groups. The main goal of this paper is to establish PT- and PST-versions o…
Variations of selective separability II: Discrete sets and the influence of convergence and maximality
2012
A space $X$ is called selectively separable(R-separable) if for every sequence of dense subspaces $(D_n : n\in\omega)$ one can pick finite (respectively, one-point) subsets $F_n\subset D_n$ such that $\bigcup_{n\in\omega}F_n$ is dense in $X$. These properties are much stronger than separability, but are equivalent to it in the presence of certain convergence properties. For example, we show that every Hausdorff separable radial space is R-separable and note that neither separable sequential nor separable Whyburn spaces have to be selectively separable. A space is called \emph{d-separable} if it has a dense $\sigma$-discrete subspace. We call a space $X$ D-separable if for every sequence of …