11 research outputs found
Hypo-hyperparathyroidism with normal 1,25 dihydroxycholecalciferol.
No full textVitamin D deficiency and primary hyperparathyroidism (PHPT) are two common conditions, especially in postmenopausal women. Vitamin D deficiency is said to be even more frequent in PHPT patients than in the general population due to an accelerated conversion of 25-hydroxy vitamin D (25OHD) into calcitriol or 24-hydroxylated compounds
Analyse en voorspelling van het getij bij Vlissingen d.m.v. de Systeemaanpak volgens Munk en Cartwright
No full textDe gangbare methoden om het getij te analyseren en voorspellen zijn de harmonische methoden. Bij deze methoden worden de frequenties van de getijkomponenten bekend verondersteld, zodat uit een getijwaarnemingenreeks de bijbehorende amplituden en fasen kunnen worden bepaald. Munk en Cartwright (Lit.10) hebben met hun aanpak een geheel andere methode geintroduceerd. Bij deze methode worden veranderingen in de gravitatiepotentiaal rond de aarde en meteorologische veranderingen als ingangssignaal beschouwd op een "black box" systeem, waarvan het verticale getij op een bepaalde plaats (A) op aarde het uitgangssignaal is. Beoogd wordt om m.b.v. een getijwaarnemingenreeks van A de impuls- of frequentieresponsiefunktie van het systeem voor A te berekenen. Reeds eerder is er aan de Technische Hogeschool Delft onderzoekverricht (Lit.19) naar de mogelijkheidom deze methode op het getij bij Vlissingen toe te passen, waarbij de analyse was beperkt tot de invloeden van de gravitatiepotentiaal. Voortbouwend op dat onderzoek is in dit onderzoek geprobeerd het resultaat van de analyse en de voorspelling m.b.v. de systeemaanpak van Munk en Cartwright te verbeteren. Ook in dit onderzoek is afgezien van de mogelijkheid de meteorologische invloed op het getij in de analyse te betrekken. Als eerste wordt d.m.v. een breedere opzet van de berekeningen het resultaat van de zuiver lineaire berekening verbeterd. Vervolgens wordt getracht de analyse en de voorspelling verder te verbeteren door een niet-lineaire uitbreiding in het systeem mogelijk te maken. Deze uitbreiding is mogelijk met behoud van het lineaire karakter van het systeem door ook ingangssignalen toe te laten die produkten van de zuivere lineaire ingangssignalen zijn. Deze produktfunkties brengen som- en verschilfrequenties van de lineaire ingangssignalen met zich mee. De mogelijkheid is nu aanwezig dat de produktfunkties gedeeltelijk of geheel lineair afhankelijk zijn van de oorspronkelijke lineaire ingangssignalen, waardoor er geen scheiding kan worden gemaakt tussen de invloed van het lineaire ingangssignaal en de invloed van de lineair afhankelijke-produktfunktie op het uitgangssignaal. M.b.v. onderlinge coherentie van de ingangsfunkties en een gladheidseis voor de frequentieresponsiefunkties wordt toch een scheiding van invloeden mogelijkgemaakt en zijn de frequentieresponsiefunkties van elke ingangsfunktie afzonderlijk te bepalen.Hydraulic EngineeringCivil Engineering and Geoscience
Gebruikershandleiding voor het programmapakket SECFLO
No full textHet programmapakket berekent de intensiteit van de secundaire stroming danwel de bodemschuifspanning t.g.v. de secundaire stroming in een gegeven tweedimensionale stromingssituatie. Het pakket is bedoeld als uitbreiding op een tweedimensionale horizontale stromingssimulatie. Het is zodanig geschreven dat het aansluit op het simulatie pakket WAQUA. Het programmapakket gebruikt als invoergegevens de door een WAQUA-simulatie geproduceerde uitvoergegevens van een bepaald gewenst tijdstip van de simulatie, met name de waterhoogte, de snelheden in twee orthogonale richtingen en de waarden van de Chezy coefficienten in de twee overeenkomstige richtingen. Het programmapakket is opgebouwd uit drie hoofdonderdelen. In het eerste hoofdonderdeel (programma modul ADAPWQ) worden de arrays voor de snelheden en de Chezy-waarden gevuld met de op de hoogte-roosterpunten gecentreerde snelheden respectievelijk Chezy-waarden. Verder wordt op basis van het gecentreerde snelheidsveld overal in het stromingsveld de locale kromtestraal van de stroming berekend. In principe zijn nu voldoende gegevens bekend om direct de momentane, locale secundaire stroming te berekenen. In het tweede hoofdonderdeel (programma modul SECINT) wordt op elk hoogte-roosterpunt de secundaire stroming berekend, rekening houdend met convectie van de secundaire stroming door de hoofdstroom. Met behulp van een iteratief numeriek proces wordt een differentiaal vergelijking opgelost die de convectie van de secundaire stroming langs een stroomlijn beschrijft. SECINT volgt na ADAPWQ. In het derde hoofdonderdeel (programma modul BOTSHE) wordt op elk hoogte-roosterpunt de bodemschuifspanning berekend zowel in de hoofd- als in de normaal-stroomrichting. Bij de berekening van de bodemschuifspanning in de normaal-richting wordt buiten de convectie van de secundaire stroming door de hoofdstroming ook de snellere relaxatie van de schuifspanning aan de bodem in rekening gebracht. BOTSHE volgt na ADAPWQ.Hydraulic EngineeringCivil Engineering and Geoscience
Simulation of flow in rivers and tidal channels with an implicit finite difference method of the ADI-type
No full textIn order to make predictions for the morphology of an alluvial bottom a thorough knowledge of the flow pattern is needed. In tidal channels, without a nett discharge over the tidal period, the main flow effects on the morphology will, on an average, remain relatively small because of the tidal variation. Therefore second order flow phenomena become important. In particular the secondary flow is important, because it gives rise to bottom slopes transverse to the main flow. This research, which is financially supported by the directorate of the Deltadienst of Rijkswaterstaat, concerns the determination of the secondary flow in tidal channels like estuaries as the Eastern Scheldt based on a known depth averaged velocity field. The depth averaged velocities must be computed with a high accuracy in order to make a reasonable determination of the secondary flow. For the computation of depth averaged velocities usually an implicit finite difference method of the ADI-type is used. In these methods the depth averaged equations of motion, together with the depth averaged continuity equation, together called the shallow water equations, are solved by means of an Alternating Direction Implicit computation using a spatial staggered grid. A simplification of the effective stress term in the shallow water equations is made to economize the computation. Although the velocity parameters and water level parameter are treated implicitly, the convective and diffusion terms are represented explicitly in the difference equations, which can give rise to instability of the numerical computation. The computation is executed with an imposed diffusion coefficient in order to suppress this instability. In this report an investigation is done concerning the diffusion coefficient and its influence on the velocity distribution in a steady or quasi-steady flow in rivers and estuaries. Estimates of the physical lateral viscosity for the same flows are made and their influence on the velocity distribution is discussed.Hydraulic EngineeringCivil Engineering and Geoscience
Improved simulation of main flow and secondary flow in a curved open channel
No full textFor the computation of depth averaged flows in tidal channels and rivers a recently developed fully implicit finite difference method of the ADI-type proved vastly superior to the partly explicit variants, commonly used. The fully implicit variant allowed a relatively large time step in combination with arealistic lateral diffusion coefficient. The fully implicit method, used, requires a square grid for the time being. The irregular numerical representation of the sidewalls of a curved channel or flume gives rise to disturbances in the computed flow field. In this report a correction scheme to keep the disturbances small is considered. In this scheme a correction is realized by a modification of the depth near the sidewalls. The correction scheme is actually a combination of two different corrections. The first correction is aimed at forcing the velocity at corner points of the computational grid in the direction of the physical boundary. The second correction compensates for the local narrowing and widening of the flow by the irregular numerical representation of the sidewalls. The influences of both corrections appear to be small when applied separately, but the combination of the two corrections has, however, important consequences. The application of the combined corrections on the simulation of steady flow in a curved flume with a rectangular cross-section annihilates nearly the important disturbances caused by the use of a rectangular grid. For a curved flume with the geometrical proportions of a river, in which case the disturbances proved much less important, a less important amelioration is obtained. For flow in tidal channels even smaller disturbances and less improvement are expected. The effect of the corrections is very sensitive to the exact waterdepth at the sidewalls. In time dependent flows it is therefore difficult to apply the right corrections. Further improvement will have to await the possibility to use a curvilinear grid in the fully implicit finite difference method. This research is aimed at the computation of secondary flow in tidal channels based on the depth averaged velocity field. The improved computation of the depth averaged velocity field brings about an improved computation of the secondary flow. Knowledge of the secondary flow in a tidal channel is essential for predictions about the morphology of the bottom.Hydraulic EngineeringCivil Engineering and Geoscience
Intra-mammary pressure changes in the lactating cow.
No full textThe object of this study was to establish the nature of the intra-mammary pressure changes that occur in the udder of the lactating dairy cow during different phases of lactation. The author was, in addition, interested in the study of the various factors responsible for these changes.
Results have shown marked and rapid fluctuations in the intra-mammary pressure at the time of milking. Stimulation of milk ejection by manipulation of the udder caused a spectacular increase in the initial intra-mammary pressure. On milking a drop in the pressure was recorded. The extent of this fall in pressure was found to be influenced by the amount of milk removed from the udder. On complete milking the intra-mammary pressure dropped to the minimum level.
The pressure in the hind quarters was found to be in most cases higher than in the fore-quarters indicating that the level of the intra-mammary pressure in each quarter was under some influence of the quantity of milk present.
A fall in the intra-mammary pressure of a milked quarter had no effect on that of the other unmilked quarters.
Intra-mammary pressure subsequent to the injection of oxytocin before milking as well as after complete milking was recorded. The administration of oxytocin under both of these conditions resulted in a rise of the pressure, which, however, was not well marked.
Considerable effect of the conditioned reflexes and of the emotional state of the animal on the intra-mammary pressure was observed during this work.Land and Food Systems, Faculty ofGraduat
Photon budget analysis for fluorescence lifetime imaging microscopy
No full textWe have constructed a mathematical model to analyze the photon efficiency of frequency-domain fluorescence lifetime imaging microscopy (FLIM). The power of the light source needed for illumination in a FLIM system and the signal-to-noise ratio of the detector have led us to a photon “budget.” These measures are relevant to many fluorescence microscope users and the results are not restricted to FLIM but applicable to widefield fluorescence microscopy in general. Limitations in photon numbers, however, are more of an issue with FLIM compared to other less quantitative types of imaging. By modeling a typical experimental configuration, examples are given for fluorophores whose absorption peaks span the visible spectrum from Fura-2 to Cy5. We have performed experiments to validate the assumptions and parameters used in our mathematical model. The influence of fluorophore concentration on the intensity of the fluorescence emission light and the Poisson distribution assumption of the detected fluorescence emission light have been validated. The experimental results agree well with the mathematical model. This photon budget is important in order to characterize the constraints involved in current fluorescent microscope systems that are used for lifetime as well as intensity measurements and to design and fabricate new systems.IST/Imaging Science and TechnologyApplied Science
Measuring and modeling coastal dune development in the Netherlands
No full textStructural EngineeringCivil Engineering and Geoscience
Statistical degradation modelling of Poly(D,L-lactide-co-glycolide) copolymers for bioscaffold applications
No full text[Abstract] This methodology permits to simulate the performance of different Poly(D,L-lactide-co-glycolide) copolymer formulations (PDLGA) in the human body, to identify the more influencing variables on hydrolytic degradation and, thus, to estimate biopolymer degradation level. The PDLGA characteristic degradation trends, caused by hydrolysis processes, have been studied to define their future biomedical applications as dental scaffolds. For this purpose, the mass loss, pH, glass transition temperature (Tg) and absorbed water mass of the different biopolymers have been obtained from samples into a phosphate-buffered saline solution (PBS) with initial pH of 7.4, at 37°C (human body conditions). The mass loss has been defined as the variable that characterize the biopolymer degradation level. Its dependence relationship with respect to time, pH and biopolymer formulation has been modelled using statistical learning tools. Namely, generalized additive models (GAM) and nonlinear mixed-effects regression with logistic and asymptotic functions have been applied. GAM model provides information about the relevant variables and the parametric functions that relate mass loss, pH and time. Mixed effects are introduced to model and estimate the degradation properties, and to compare the PDLGA biopolymer populations. The degradation path for each polymer formulation has been estimated and compared with respect to the others for helping to use the proper polymer for each specific medical application, performing selection criteria. It was found that the mass loss differences in PDLGA copolymers are strongly related with the way the pH decay versus time, due to carboxylic acid groups formation. This may occur in those environments in which the degradation products remain relatively confined with the non degraded mass. This is the case emulated with the present experimental procedure. The results show that PDLGA polymers degradation degree, in terms of half life and degradation rate, is increasing when acid termination is included, when DL-lactide molar ratio is reduced, decreasing the midpoint viscosity, or when glycolide is not included.The research of Salvador Naya and Javier Tarrío- Saavedra has been partially supported by the Xunta de Galicia (Centro Singular de Investigación de Galicia accreditation [ED431G/01 2016-2019] and Grupos de Referencia Competitiva [ED431C2016-015]) and by the MINECO [Grant MTM2014-52876-R]. These grants are cofunded by the European Union (European Regional Development Fund - ERDF). The research of Yaroslava Robles has been supported by the Ecuador’s Secretaría Nacional de Educación Superior, Ciencia, Tecnología e Innovación (SENESCYT) and Inditex-UDC International Doctoral School Grant for pre-doctoral students. Francisco Javier García Sabán and Sara QuintanaPita are employed by DevelopBiosystem SL. DevelopBiosystem SL provided support in the form of salaries for J.G.S and S.Q.P. authors, but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the author contributions section.
The following information is missing from the Funding section: The research of Salvador Naya and Javier Tarrío Saavedra has also been supported by MINECO [Grant MTM2017- 82724-R].The research of Salvador
Naya and Javier Tarrío Saavedra has also been supported by MINECO [Grant MTM2017-
82724-R].Xunta de Galicia; ED431G/01 2016‐2019Xunta de Galicia; ED431C2016‐01
The view from the backbench : Irish Nationalist MPs and their work, 1910-1914
No full textAvailable from British Library Document Supply Centre- DSC:DXN065144 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
