The subject of this thesis is the simulation study of the development of extensive air show ers produced by very high energy gamma-ray and hadronic cosmic rays with respect to the Cherenkov light they produce, and its imaging in ground based telescopes. Chapters 1-4 are introductory: Chapter 1 covers the mechanisms responsible for the production of very high energy gamma-rays, whereas, chapter 2 focusses on the development of extensive air showers and Cherenkov light production. Chapter 3 covers the instrumentation used to measure the Cherenkov light using the imaging atmospheric Cherenkov technique. Chapter 4 covers known and possible sources of very high energy gamma-rays. Chapters 5, 6 and 7 cover research performed by the author: Chapter 5 discusses some of the differences between three popular extensive air shower simulations codes, namely ALTAI, CORSIKA and MOCCA. Chapter 6 details the simulation of the response of two ground based imaging atmospheric Cherenkov telescope (the Durham Mark 6 and stand-alone H.E.S.S. telescopes), and in particular details the derivation of the flux of the x-ray selected BL-LAC PKS 2155-304 with the Durham Mark 6 telescope. This represents the refinement of a published measurement given an improved telescope simulation. The significance of the signal seen is 6.8o, and the integral flux derived above 1.5 TeV (assuming a differential spectral slope of-2.6) is {2.5±0.7stat ± (^0.5)(_1.6syst) x 10(^-7) photons m(^-2) s(^-1) Chapter 7 discusses the importance of the atmosphere, and the results of shower simulations under different atmospheric assumptions are presented, which indicate the importance of atmospheric calibration for the new generation of Cherenkov telescopes. The results of this chapter suggest that to first order large changes in the low level aerosol concentration have a much more significant effect on the trigger rate of a stand-alone H.E.S.S. telescope, than on the Hillas parameter distributions seen. Chapter 8 brings together the work done in this thesis, and highlights a final set of fluxes for the active galactic nuclei sources seen with the Durham Mark 6 telescope, many of which will form future sources to be measured with the H.E.S.S. system. The current status of the stand-alone H.E.S.S. system is also covered in chapter 8. The thesis concludes with a further brief discussion of the future prospects for imaging atmospheric Cherenkov astronomy.

Two experiments were conducted during the winters of 2012-13 (yr 1) and 2013-14 (yr 2), to evaluate 3 winter feeding systems: (i) field grazing standing whole plant corn (SC) cv. ‘DKC 26-25’ (yr 1, CP = 9.5%, TDN = 66.1%; yr 2, CP = 9%, TDN = 69.8%), (ii) field grazing swathed barley hay (SB) cv. ‘Ranger’ (yr 1, CP = 13.2%, TDN = 56.8%; yr 2, CP = 10%, TDN = 61.9% and (iii) barley hay bales fed in drylot pens (DL) cv. ‘Ranger’ (yr 1, CP = 13.1%, TDN = 53.2%; yr 2, CP = 8.2%, TDN = 55.2%). Forages were allocated on a 3-4 d interval in SC and SB systems. The specific objectives were to compare crop yield and agronomy, beef cow performance, reproductive efficiency and system costs in experiment 1 (EXP 1); and ruminal pH, SCFA and ammonia concentration in experiment 2 (EXP 2). In EXP 1, 60 dry, pregnant Black Angus cows (yr 1, 644 kg ± 72 kg; yr 2, 672 kg ± 66 kg) at mid-gestation, stratified by body weight (BW) were allocated to 1 of 3 replicated (n=2) winter grazing treatments for 77 d in yr 1 and 78 d in yr 2. Increases in rib fat were greater (P = 0.02) for SC cows compared to SB cows (1.6 vs 0.3 mm, respectively). Estimated DMI was lower (P < 0.01) for SC cows (9.1 kg/d) compared to SB and BH cows (14.3 and 13.0 kg/d, respectively) which did not differ (P > 0.05) from each other. Calves born to cows grazing SC were heavier (P ˂ 0.01) at birth compared to calves from SB and BH cows (43, 40 and 40 kg, respectively). Changes in cow BW and average daily gain (ADG) were lower (P < 0.01) and negative in year 2 (BW change, 23.8 and -4.9 kg; ADG, 0.3 and -0.1 kg for yr 1 and 2, respectively). The number of calves born in first 21 d was 44% higher (P < 0.01) in yr 1 compared to yr 2. Economic analysis revealed that total costs were greatest for BH ($2.75/cow/d) compared to SC and SB ($2.06 and $2.00 cow/d, respectively) systems. In EXP 2, 9 cannulated beef heifers were cycled through the 3 winter systems concurrently within EXP 1, in a replicated 3 × 3 Latin square design, for 63 d to evaluate effect of forage type and day of allocation on rumen fermentation. Results from EXP 2 indicated an increase (P < 0.01) in minimum pH of cannulated heifers from d 1 to d 3 of forage allocation in SC and SB systems. Lower (P < 0.01) minimum and mean pH and increased duration and area (P < 0.01) under pH 5.8 were observed in yr 2 in SC and yr 1 in SB. In yr 2, total SCFA, acetate and propionate concentration increased (P < 0.01) in SB heifers, but butyrate concentration increased (P < 0.05) in SC heifers compared to yr 1. Ruminal fermentation was unaffected (P > 0.05) by day of forage allocation and yr of study in BH system. Results from EXP 1 and EXP 2 suggest that both SC and SB systems are cost effective alternatives to BH system, and do not negatively affect cow reproductive performance following winter grazing. However, yearly differences in weather and seeding date of forages can have a profound effect on nutrient composition of forages, and can cause variations in cow performance and rumen metabolism during the period of extensive winter grazing.

No description available.

The use of polymeric materials in the manufacturing industry has vastly increased since the 1950’s. Because of the large amounts of material involved in modern processing operations, attempts have been made over the years to numerically simulate the processes, in the hope of optimizing operating parameters. However, in contrast to other, more traditional materials such as steel or glass, there is not a well understood connection between the microscopic structure and the (highly non-linear) macroscopic physical response of polymers. Because of this lack of microscopic cause - macroscopic effect knowledge, many descriptions of the physical response of polymers are largely phenomenological ones; that is, the equations used to model the stress/strain response make no attempt to convey information about the microscopic structure of the material. In the present work, five constitutive equations - Mooney-Rivlin, Ogden, G’Sell Two-term Polynomial and K-BKZ - are used to model the stress/strain response of two different polymers commonly used in thermoforming and blowmolding operations, ABS and HDPE, to uniaxial elongation and equibiaxial extension. The models are compared to experimental stress/strain data obtained from an industrial source, and the applicability of their predictions are investigated with regards to variations in strain, strain rate and temperature. Lastly, since the vast majority of real processes involve biaxial, not uniaxial, deformations, the ability of the models to predict equibiaxial response using parameters fit solely to uniaxial data is considered, in order to investigate the possibility of being able to forego the need for expensive, difficult biaxial tests. / Thesis / Master of Engineering (ME)

Depicting the problems with teacher-centered English reading classes in Korea, this report proposes extensive reading as a possible means to address the issues related to intensive reading. Literature on extensive reading is reviewed to provide a rationale for including it in reading curriculum. Research has shown that extensive reading, with its focus on reading large amounts of self-selected, easy and interesting materials, offers a wide range of learning benefits to second language learners. Based on research findings, this report presents some pedagogical suggestions for the implementation of extensive reading in Korean secondary schools by exploring practical issues, including materials, teacher roles, activities, and assessment in an extensive reading program. / text

BACKGROUND: Though direct oral anticoagulants (DOACs) have become a standard of care in the treatment of acute deep vein thrombosis (DVT), it is our observation that physicians tend to initiate heparin or low-molecular-weight heparin, hereafter called “heparin”, for the treatment of extensive DVT or phlegmasia cerulea dolens (PCD). This might be due to a perception that heparin might relieve DVT-related symptoms more quickly than DOACs. Whether these assumptions are true has not been evaluated. METHODS: We conducted a survey of thrombosis specialists in North America to explore the practical management of anticoagulant therapy in patients with extensive DVT, and the underlying reasons for the selection of heparin over DOACs. A cross-sectional, web-based survey was distributed to thrombosis specialists who are members of four thrombosis societies. RESULTS: Eighty-nine respondents provided consent. Most respondents selected DOACs over heparin in a case scenario representing mild DVT-related symptoms and limited thrombus involvement (81% vs. 19%). Most respondents selected heparin over DOACs in a case scenario representing early stage PCD (84% vs.16.3%) or a patient with high bodyweight (72% vs. 28%). In a case scenario representing extensive DVT, 57.4% of the respondents selected heparin, whereas, 42.6% selected DOACs. In the respondents who selected heparin over DOACs, the major reason was that heparin might relieve DVT-related symptoms more quickly because of its anti-inflammatory effects. DISCUSSION: Severity of DVT-related symptoms, thrombus extent, and bodyweight play a role in the selection of anticoagulant therapy. Despite a lack of evidence to support the hypothesis with respect to which anticoagulant is superior, most thrombosis specialists selected heparin over DOACs in patients with severe DVT-related symptoms and extensive thrombus involvement. Observation of variations in the selection of anticoagulant therapy for the treatment of extensive DVT also indicates that clinical trials in this patient population are needed. / Thesis / Master of Science (MSc)

No description available.

Thesis (doctoral)--Rheinische Friedrich-Wilhelms-Universität zu Bonn, 1999.

No description available.

No description available.