Chloride dispersion in packed columns during saturated steady flow     

JENS RAUNSØ 《European Journal of Soil Science》1983,34(2):249-262

Chloride transport was investigated in four columns packed with glass spheres, spheres of a cation exchange resin, a loamy sand and a sandy loam, respectively. Using step input, vertical downward flow and relatively high flow-rates, 0.01 m KCl displaced water in the column packed with glass spheres, otherwise 3.33 × 10^?4m CaCl₂ displaced or was displaced by 3.33 × 10^?3m CaCl₂. The breakthrough curves of chloride were analysed to give dispersion coefficients and mobile volumes. It was found that (i) chloride exchanged between mobile and immobile region in the sandy loam, (ii) the dispersion coefficient (K) was linearly related to pore flow velocity (U) for the individual columns, and that (iii) the ratio of dispersivity (dK/dU) to median grain diameter increased with increasing standard deviation of the logarithmicnormal grain size distribution.  相似文献   

COMPARATIVE STRUCTURAL ANALYSIS OF THE CANINE FEMORAL HEAD IN LEGG-CALVÉ-PERTHES DISEASE     

CORNELIA SCHERZER  HENNING WINDHAGEN  JENS NELLESEN  HORST-ARTUR CROSTAK  KARL ROHN  FRANK WITTE  FRITZ THOREY  MICHAEL FEHR  GREGOR HAUSCHILD 《Veterinary radiology & ultrasound》2009,50(4):404-411

The goal of this study was to examine the microarchitecture of the trabecular bone of the canine femoral head using microcomputed tomography (micro-CT) technology. Specifically, we assessed changes seen in the femoral head in dogs with Legg-Calvé-Perthes disease and compared this with changes seen in dogs with hip dysplasia and coxofemoral luxation. Femoral heads from healthy animals were examined as a control. In total, 38 femoral heads were studied. Rules for defining spherical volumes (region of interest) for determination of the structural parameters within the trabecular structure were established using micro-CT images. The following parameters were determined directly in three dimensions: bone volume fraction, surface volume fraction, trabecula thickness, trabecular count, trabecular spacing, and connectivity. Characteristic femoral head changes were found for each condition. An unexpected result was found that contradicts the prevailing understanding of Legg-Calvé-Perthes disease. Instead of observing a thickening of the bone trabeculae caused by layering of new bone matrix on top of necrotic trabeculae, we observed an increase in trabecular count and a smaller trabecular thickness. From this it may be concluded that trabecular regeneration is more prominent or prevails over the characteristically described layering processes in the revascularization and repair processes occurring in this illness.  相似文献   

NORMAL CANINE BRAIN MATURATION AT MAGNETIC RESONANCE IMAGING     

BILL GROSS  DAVID GARCIA‐TAPIA  ELIZABETH RIEDESEL  NORMAN MATTHEW ELLINWOOD  JACKIE K. JENS 《Veterinary radiology & ultrasound》2010,51(4):361-373

The normal neonatal canine brain exhibits marked differences from that of the mature brain. With development into adulthood, there is a decrease in relative water content and progressive myelination; these changes are observable with magnetic resonance imaging (MRI) and are characterized by a repeatable and predictable time course. We characterized these developmental changes on common MRI sequences and identified clinically useful milestones of transition. To accomplish this, 17 normal dogs underwent MRI of the brain at various times after birth from 1 to 36 weeks. Sequences acquired were T1‐weighted (T1W), T2‐weighted (T2W), fluid attenuated inversion recovery, short tau inversion recovery, and diffusion weighted imaging sequences. The images were assessed subjectively for gray and white matter relative signal intensity and results correlated with histologic findings. The development of the neonatal canine brain follows a pattern that qualitatively matches that observed in humans, and which can be characterized adequately on T1W and T2W images. At birth, the relative gray matter to white matter signal intensity of the cortex is reversed from that of the adult with an isointense transition at 3–4 weeks on T1W and 4–8 weeks on T2W images. This is followed by the expected mature gray matter to white matter relative intensity that undergoes continued development to a mostly adult appearance by 16 weeks. On the fluid attenuated inversion recovery sequence, the cortical gray and white matter exhibit an additional signal intensity reversal during the juvenile period that is due to the initial high relative water content at the subcortical white matter, with its marked T1 relaxation effect.  相似文献   

COMPUTED TOMOGRAPHY OF THE LUNG OF HEALTHY SNAKES OF THE SPECIES PYTHON REGIUS, BOA CONSTRICTOR, PYTHON RETICULATUS, MORELIA VIRIDIS, EPICRATES CENCHRIA, AND MORELIA SPILOTA     

MICHAEL PEES  INGMAR KIEFER  JENS THIELEBEIN  GERHARD OECHTERING  MARIA-ELISABETH KRAUTWALD-JUNGHANNS 《Veterinary radiology & ultrasound》2009,50(5):487-491

Thirty-nine healthy boid snakes representing six different species ( Python regius, Boa constrictor, Python reticulatus, Morelia viridis, Epicrates cenchria , and Morelia spilota ) were examined using computed tomography (CT) to characterize the normal appearance of the respiratory tissue. Assessment was done subjectively and densitometry was performed using a defined protocol. The length of the right lung was calculated to be 11.1% of the body length, without a significant difference between species. The length of the left lung in proportion to the right was dependent on the species examined. The most developed left lung was in P. regius (81.2%), whereas in B. constrictor , the left lung was vestigial or absent (24.7%). A median attenuation of −814.6 HU and a variability of 45.9 HU were calculated for all species with no significant difference between species. Within the species, a significantly higher attenuation was found for P. regius in the dorsal and cranial aspect of the lung compared with the ventral and caudal part. In B. constrictor , the reduced left lung was significantly hyperattenuating compared with the right lung. Results of this study emphasize the value of CT and provide basic reference data for assessment of the snake lung in these species.  相似文献   

Diseases of the Female Reproductive Organs of Pet Birds     

JENS HASHOLT 《The Journal of small animal practice》1966,7(4):313-320

Abstract— During the period 1960-1961, 1819 birds were received for treatment at the Animal Hospital at Emdrup, Copenhagen. Of these, 148 were treated for diseases of the reproductive organs (8 male and 140 female). The symptoms and treatment of ovarian cysts and tumours, egg-binding, prolapse of the oviduct, and salpingitis are described. Cysts and tumours were observed in twenty-two cases, and of these thirteen have been cured. Retention of egg: observed in thirty-six cases, cured in thirty-two. Prolapsus ovid: observed in thirty-eight cases, cured in eighteen. Salpingitis: observed in forty-two cases, cured in thirty-five. Résumé— Pendant la période 1960-1961, 1819 oiseaux ont été traǐtés à l'hǒpital d'animaux à Emdrup, Copenhague. Parmi ceaux-ci 148 furent soignés puor des maladies des organes de reproductions (8 males et 140 femelles). Les symptomes et le traǐtement des tumeurs et kystes ovariens, rétention de l'oeuf, chute de l'oviducte et salpingites sont tous décrits. Des kystes et des tumeurs furent observés dans 21 cas, et parmi ceux-ci treize ont été guéris. Retention de l'oeuf: observée dans trente six cas, trente deux guéris. Prolapsus de l'oeuf: observé dans trente huit cas, dix huit guéris. Salpingites: observée dans quarente deux cas, trente cinq guéris. Zusammenfassung— Von 1960 bis 1961 wurden 1819 Vogel zur Behandlung in das Tierlazarett in Emdrup, Kopenhagen, eingeliefert. Davon wurden 148 (8 Männchen und 140 Weibchen) auf Krankheiten der Fortpflanzungsorgane behandelt. Es werden die Symptome und Behandlung von Eierstockzysten und Geschwulsten, Eirentention, Inversion der Eileiter und Salpingitis beschrieben. Zysten und Geschwulste wurden in zweiundzwanzig Fällen beobachtet, wovon dreizehn geheilt wurden. Eirentention wurde in sechsunddreissig Fällen beocachtet und in zweiundreissig Fallen beheilt: in achtunddreissig Fällen wurde Prolapsus ovid gefunden, davon wurden achtsehn geheilt; Salpingitis kam in zwieunvierzig Fallen vor und wurde in fünfundreissig Fällen geheilt.  相似文献