Ærter som kvælstofsamler i vintersæd

I løbet af vinteren optager afgrøderne stort set ikke kvælstof og størstedelen af det plante-tilgængelige kvælstof der måtte befinde sig i jorden bliver udvasket. Der er således ikke noget tilgængeligt kvælstof tilstede, når planterne genoptager væksten idet tidlige forår, og planterne "sulter" indtil det er muligt at udbringe gødning. I det forløbne år har gårdejer Esben Tøttrup, Vindum i samarbejde med Danmarks JordbrugsForskning og LandboCenter Midt gennemført markforsøg med ærter som grøngødning i vintersæd. Formålet med at så ærter sammen med vintersæd skulle være, at det kvælstof, som ærterne opsamler i løbet af efteråret bliver lagret vinteren over og frigivet som startgødning i det tidlige forår, når kornplanterne genoptager væksten

Marketing Research

xvi, 742 ha

Modélisation et caractérisation d'un système TEMP à collimation sténopée dédié à l'imagerie du petit animal

My thesis focuses on the development of several quantitative reconstruction methods dedicated to small animal Single Photon Emission Computed Tomography. The latter is based on modeling the acquisition process of a 4-heads pinhole SPECT system using Monte Carlo simulations.The system matrix approach, combined with the OS-EM iterative reconstruction algorithm, enabled to characterize the system performances and to compare it to the state of the art. Sensitivity of about 0,027% in the center of the field of view combined with a tomographic spatial resolution of 0,87 mm were obtained.The major drawbacks of Monte Carlo methods led us to develop an efficient and simplified modeling of the physical effects occurring in the subject. My approach based on a system matrix decomposition, associated to a scatter pre-calculated database method, demonstrated an acceptable time for a daily imaging subject follow-up (1h), leading to a personalized imaging approach. The inherent approximations of the scatter pre-calculated approach have a moderate impact on the recovery coefficients results, nevertheless a correction of about 10% was achieved.Le développement de plusieurs méthodes de reconstruction quantitatives dédiées à la Tomographie par Emission Mono Photonique du petit animal a été au cœur de cette thèse. Dans cette optique, une modélisation rigoureuse par simulation Monte Carlo du processus d’acquisition du système disponible, a été mise en place et validée. La modélisation matricielle combinée à l’algorithme de reconstruction itératif OS-EM, a permis la caractérisation des performances du système. Les valeurs de sensibilité et de résolution spatiale tomographique sont respectivement de 0,027% au centre du champ de vue et de 0,87 mm. Les limitations majeures des méthodes Monte Carlo nous ont conduit à développer une génération matricielle efficace et simplifiée des effets physiques occurrents dans le sujet. Mon approche, basée sur une décomposition de la matrice système, associée à une base de données pré-calculées, a démontré un temps acceptable pour un suivi quotidien (1h), conduisant à une reconstruction d’images personnalisée. Les approximations inhérentes à l’approche mise en place ont un impact modéré sur les valeurs des coefficients de recouvrement, une correction d’environ 10% ayant été obtenue

A similar 24-h blood pressure control is obtained by zofenopril and candesartan in primary hypertensive patients

Objective. To compare the antihypertensive effect of treatment with zofenopril vs candesartan by office and ambulatory blood pressure (BP). Design and methods. Following a 2-week wash-out from previous treatment, 236 grade I-II primary hypertensive patients were randomized double-blind to 12 weeks treatment with zofenopril 30 mg or candesartan 8 mg od. After 4 weeks, treatment was doubled in responder non-normalized (office systolic BP≥140 mmHg and office diastolic BP reduction ≥10 mmHg) or non-responder patients (office systolic BP≥140 mmHg and office diastolic BP reduction <10 mmHg). Following a further 4 weeks, non-responder non-normalized patients were withdrawn. Results. In the intention-to-treat population, office systolic BP and diastolic BP reductions after 12 weeks of treatment were similar between the two groups (zofenopril: 21±11/15±8 mmHg, n=114 vs C: 20±11/15±7 mmHg (candesartan; p=NS). Also 24-h ambulatory BPs were equally reduced by zofenopril and candesartan (7±13/ 5±8 mmHg vs 7±12/5±8 mmHg; p=NS). The trough-to-peak ratio and smoothness index were not sigficantly different between zofenopril and candesartan. Tolerability of both drugs was good. Conclusions. Monotherapy with zofenopril and candesartan similary reduced office and 24-h BPs. Since almost 90% of patiens were normalized by either zofenopril or candesartan, this result suppots the importance of considering low- or high-dose monotherapies as initial for most hypertensive patients of mild degree