A numerical method for the calculation of the powder flow properties obtained with the Jenike flow factor tester

A yield locus obtained with the Jenike Flow factor tester can be represented by the Warren Spring equation.\ud In this equation σ and π are the normal and shear stresses respectively, C and T the cohesion and tension, and N a curvature parameter constant for one material.\ud Based on this equation and assuming a constant ratio K = C/T, several partly graphical partly numerical solution methods are known.\ud The pure numerical method described in this article has several advantages over the graphical methods used so far. The method presents precise objective results, acquired directly from the measured data. No more or less subjective manipulations are required.\ud \ud Although the method seems rather complicated, the required number of iterations is relatively low because of the rapid convergence of the iteration process. This leads, together with the simplicity of the formulas used, to a relatively small computing time.\ud \ud It appears that with the assumption of a constant ratio K = C/T for one material, all data reqired for the Jenike hopper design method can also be computed purely numerically by means of a least-squares method using Newton's zero finding thus required are not influenced by the initial estimations. The results obtained are only a function of the measured points and interpretative errors are eliminated

Splenectomie

De functie van de milt is niet nauwkeurig bekend. Vroeger werd algemeen aangenomen, dat de milt een bloedreservoir zou zijn. Tegenwoordig vermoedt men, dat via verschillende stoffen (arterenol) de milt invloed uitoefent op het circulerend bloedvolumen. Ook bij de afweer tegen infecties speelt de milt een rol. Het bestaan van milthormonen kan niet meer ontkend worden. Belangrijk is de functie van de milt in verband met de samenstelling van het bloed. Onder pathologische omstandigheden kunnen een of meerdere soorten cellen in verminderd aantal aanwezig zijn (hypersplenie). Microscopisch is de diagnose hypersplenie niet te stellen. ... Zie: Samenvatting

Cerebellar Impact on Thalamocortical Networks in Epilepsy

The aim of this thesis is to further elucidate neural mechanisms underlying the role of the cerebellum in generalized epilepsy and more specifically if the cerebellum can be used as a remote control site to influence thalamocortical networks in health and during epilepsy

Deiodination and conjugation of T3 and other iodothyronines

Iodine enters the thyroid follicular cells as inorganic iodide and is incorporated through a series of metabolic steps into the main thyroid hormones thyroxine (T4 ) and 3,3',5-triiodothyronine (T3 ). Consecutive steps in this metabolic sequence are: 1) active transport of iodide by the thyroid follicular cell; 2) iodination of tyrosyl residues of thyroglobulin at the apical membrane; 3) coupling of mono- and diiodotyrosine molecules within thyroglobulin to form T4 and T 3 ; 4) proteolysis of thyroglobulin, with release of T4, T3 and iodotyrosines; and 5) deiodination of iodotyrosines within the thyroid and reutilization of the liberated iodide. The iodothyronines are then secreted into the blood. The production and secretion of iodothyronines by the thyroid are under control of thyroid stimulating hormone (TSH) secreted by the anterior pituitary gland. TSH binds to a specific plasma membrane receptor on the surface of the follicular cells and exerts its action mainly via the second messenger cAMP (1). The secretion of TSH is regulated by two interacting elements: neural control by the hypothalamus (stimulation by TRH, inhibition by somatostatin (2) and dopamine (3)) and negative feedback control by thyroid hormones (4-6). The main product secreted by the thyroid is T4 (structural formulas of the iodothyronines are shown in Fig. 1). In the normal adult the mean T4 secretion rate is -115 nmol/d per 70 kg body weight (BW). Thyroidal secretion of T 3 amounts to-g and of 3,3',5'-triiodothyronine (reverse T3 , rT 3) to -z nmol/d per 70 kg BW (for a review, see ref. 7). As the total production rates of T3 (-43 nmol/d) and rT3 (45-90 nmol/d) are much higher (7), it will be clear that the production of these iodothyronines occurs predominantly outside the thyroid. Contribution of thyroidal seretion to the circulating diiodothyronines 3,3'-T2 , 3,5-T2 and 3',5'-T2 is negligible (8,9)

Synchronicity and rhythmicity of purkinje cell firing during generalized spike-and-wave discharges in a natural mouse model of absence epilepsy

Absence epilepsy is characterized by the occurrence of generalized spike and wave discharges (GSWDs) in electrocorticographical (ECoG) recordings representing oscillatory activity in thalamocortical networks. The oscillatory nature of GSWDs has been shown to be reflected in the simple spike activity of cerebellar Purkinje cells and in the activity of their target neurons in the cerebellar nuclei, but it is unclear to what extent complex spike activity is implicated in generalized epilepsy. Purkinje cell complex spike firing is elicited by climbing fiber activation and reflects action potential firing in the inferior olive. Here, we investigated to what extent modulation of complex spike firing is reflected in the temporal patterns of seizures. Extracellular single-unit recordings in awake, headrestrained homozygous tottering mice, which suffer from a mutation in the voltage-gated CaV2.1 calcium channel, revealed that a substantial proportion of Purkinje cells (26%) showed increased complex spike activity and rhythmicity during GSWDs. Moreover, Purkinje cells, recorded either electrophysiologically or by using Ca2+-imaging, showed a significant increase in complex spike synchronicity for both adjacent and remote Purkinje cells during ictal events. These seizure-related changes in firing frequency, rhythmicity and synchronicity were most prominent in the lateral cerebellum, a region known to receive cerebral input via the inferior olive. These data indicate profound and widespread changes in olivary firing that are most likely induced by seizure-related activity changes in the thalamocortical network, thereby highlighting the possibility that olivary neurons can compensate for pathological brain-state changes by dampening oscillations

Optimization of input parameters to a CN neuron model to simulate its activity during and between epileptic absence seizures

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Combining machine learning and simulations of a morphologically realistic model to study modulation of neuronal activity in cerebellar nuclei

Abstract from 23rd Annual Computational Neuroscience Meeting: CNS 2014 © 2014 Alva et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Epileptic absence seizures are characterized by synchronized oscillatory activity in the cerebral cortex that can be recorded as so-called spike-and-wave discharges (SWDs) by electroencephalogram. Although the cerebral cortex and the directly connected thalamus are paramount to this particular form of epilepsy, several other parts of the mammalian brain are likely to influence this oscillatory activity. We have recently shown that some of the cerebellar nuclei (CN) neurons, which form the main output of the cerebellum, show synchronized oscillatory activity during episodes of cortical SWDs in two independent mouse models of absence epilepsy [1]. The CN neurons that show this significant correlation with the SWDs are deemed to “participate” in the seizure activity and are therefore used in our current study designed to unravel the potential causes of such oscillatory firing patternsPeer reviewe