The objective of the present study was to evaluate the effects of low input development protocols on Southeastern replacement beef females and their offspring. Fall and spring calving crossbred beef heifers managed through one of two heifer development programs (low input, LOW or conventionally developed, CON) were evaluated for metrics of uterine artery hemodynamics, patterns of heifer and offspring growth, postpartum reproductive performance, and economic efficiency. There were significant treatment × season (P = 0.0001) and season × day (P = 0.003) interactions on heifer body weight (BW) during gestation. There was a season × day interaction on total blood flow (TBF; P = 0.05) whereby TBF increased as gestation progressed and spring calving heifers displayed increased TBF. When adjusted for BW, an additional main effect of treatment was observed (P = 0.0007) in which LOW heifers had increased TBF compared to CON heifers. There were no significant main effects of treatment or season or interactions thereof on the proportion of females cycling at the start of the breeding season (P > 0.05). Additionally, there were main effects of treatment (P = 0.0095; P = 0.02) and season (P = 0.012; P = 0.007) on calf ADG and weaning weights, respectively whereby calves born to CON females grew faster than calves born to LOW heifers, and SPRING calves gained more rapidly than FALL calves. Partial budgeting demonstrated that LOW bred heifers were $250/hd less expensive to purchase than CON heifers due to lighter BW. Calves born to LOW females yielded $6.38 less per calf compared to CON calves. The discrepancy in reproductive efficiency coupled with the failure of LOW females to achieve BW similar to CON females resulted in a difference of $403/hd in average cull value between LOW and CON females in which CON females were worth more. Thus, CON females were $159.18 more profitable than LOW females when purchased as bred heifers and sold at the weaning of their first calf. In conclusion, though uterine artery BF was not negatively affected, low input heifer development resulted in sub-optimal heifer growth, poor first calf performance, and inadequate reproductive efficiency.

This thesis aims to explore possible implementations and optimizations of the lattice-Boltzmann method. This method allows modeling of fluid flow using a simulation of fictive particles. The thesis focuses on possible improvements of the existing tool HemeLB which  is designed and optimized for bloodflow modeling. Several vectorization and paralellization approaches that could be included in this tool are explored. An application focused on comparing chosen algorithms including optimizations for the lattice-Boltzmann method was implemented as a part of the thesis. A group of tests focused on comparing this algorithms according to performance, cache usage and overall memory usage was performed. The best performance achieved was 150 millions of lattice site updates per second.

Bakgrund: Hjärnskakning är en vanlig diagnos och vissa patienter upplever att fysisk ansträngning utlöser symtom lång tid efter hjärnskakningen. En förändring i reglering av cerebralt blodflöde (CBF) har visats vara en potentiell orsak bakom detta. Konditionsträning under tröskeln för symtomexacerbation kan förkorta återhämtningstiden för patienterna. På Neurorehab vid Norrlands universitetsjukhus i Umeå identifieras tröskeln med ett stegrat arbetsprov på ergometercykel. Det finns inte någon studie där transkraniell doppler (TCD) använts för att mäta förändringar i cerebralt blodflöde (CBF) under detta arbetsprov. Syfte: Att undersöka genomförbarhet och klinisk relevans av att använda TCD för mätning av blodflödeshastighet i arteria cerebri media (ACMh), hos friska män, under stegrat arbetsprov. Metod: Sex friska och regelbundet aktiva män genomförde ett stegrat arbetsprov på ergometercykel under samtidig mätning av hjärtfrekvens, blodtryck, partialtryck end-tidal CO2 (PetCO2) och blodflödeshastighet i arteria cerebri media (ACMh, mätt med TCD). Smärta från TCD-utrustning och upplevd ansträngning skattades. Tidsåtgången för TCD-tillägget samt eventuell signalförlust noterades. Resultat: Fem studiedeltagare rapporterade ökad smärta (huvudvärk), skattad med Borg CR10 skala, från TCD-utrustningen. Total tidsåtgång för TCD-tillägget var 7 minuter och 40 sekunder i median (IQR, 5 minuter och 32 sekunder). Signalförlust uppstod för en studiedeltagare på vänster sida. PetCO2 och ACMh följdes åt under arbetsprovet bortsett från avvikelser vid två tillfällen. Slutsatser: Studien visar att mätning av ACMh med TCD är genomförbart och ger relevant information om hur CBF ter sig under genomförandet av stegrat arbetsprov. TCD-utrustningen orsakade smärta vilket kan vara problematiskt vid genomförande för personer med postkontusionellt syndrom.

Einleitung: Die Vena jugularis interna (VJI) gilt als das wichtigste Gefäß der zerebralen Drainage. Es gibt jedoch Hinweise darauf, dass das vertebrale Venensystem in Abhängigkeit von der Körperposition, an der zerebralen venösen Drainage beteiligt ist. Im Rahmen dieser Arbeit soll die Bedeutung der VJI und des vertebralen Venensystems für die zerebralvenöse Drainage in unterschiedlichen Körperpositionen untersucht werden. Methode: Bei 23 gesunden Probanden wurde der Blutfluss in den VJI und den Vv. vertebrales (VV) duplexsonographisch bestimmt. Dazu wurde die Person auf einem Kipptisch gelagert. Die Messungen wurden in den Positionen -15° (Kopftieflage), 0° (horizontal), 15°, 30°, 45°, und 90° (Stehen) durchgeführt. Der arterielle zerebrale Blutfluss (CBFA) wurde in den Positionen 0° und 45° bestimmt. Ergebnisse: Der Blutfluss der VJI ging von 810 ? 360 ml/min in Kopftieflage (-15°) auf 70 ? 100 ml/min im Stehen zurück. Gleichzeitig stieg der Blutfluss VV von 20 ? 15 ml/min in Kopftieflage auf 210 ? 120 ml/min im Stehen an. Der CBFA betrug 800 ? 153 ml/min in der 0°-Position und 720 ? 105 ml/min in der 45°-Position. Diskussion: Es konnte eine deutliche Lageabhängigkeit der zerebralvenösen Drainage nachgewiesen werden. Es zeigte sich, dass die zentrale Bedeutung der VJI für die zerebrale venöse Drainage auf die liegende Position beschränkt ist. Im Stehen verläuft die zerebrale venöse Drainage weitgehend über das vertebrale Venensystem. / Background: The internal jugular veins (IJV) are considered to be the main outflow of cerebral venous blood. However, there is evidence that the vertebral venous system also forms part of the cerebral venous outflow, depending on the position of the body. This paper asseses the hemodynamic consequences of postural changes in cerebral venous drainage by color-coded duplex sonography. Methods: Volume-blood-flow-measurements were conducted in 23 healthy volunteers in supine position on a tilt table. Both IJV and VV were studied in -15° (head-down tilt), 0°, 15°, 30°, 45°, and 90° (upright position) tilt. Arterial cerebral blood flow (CBFA) was measured in 0° and 45°-position. Results: Bloodflow in the IJV dropped from 810 ? 360 ml/min in the head-down-position (-15°) to 70 ? 100 ml/min at 90°. Simultaneously blood flow in the VV increased from 20 ? 15 ml/min in -15°-position to 210 ? 120 ml/min in the 90°-position. Discussion: The results show, that the cerebral blood drainage pathways depend heavily on the inclination of the body. The role of the IJV as the main drainage pathway of the cerebral blood appears to be confined to the supine position. In the erect position, the vertebral venous system was found to be the major outflow pathway in humans.