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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Analysis of early lactation reproductive characteristics in Holstein cows

Walters, Anneke H. 24 July 2000 (has links)
Ultrasound-guided transvaginal follicular aspiration was used to obtain oocytes from cows to study follicular development and oocyte morphology. Follicular aspiration was conducted once during wk 1 to 12 postpartum on 120 lactating cows with 6 groups, separated by biweekly intervals. Approximately one half of the aspirated cows at each session were from the early groups (wk 1-2, 3-4, or 5-6) and the other half from the later groups (wk 7-8, 9-10, or 11-12). On the day of aspiration the number of follicles on each ovary, and their sizes, small (2-5 mm), medium (6-10 mm) and large (≥ 11 mm), were recorded. The collected oocytes were morphologically classified into 4 grades, with 4 = excellent, 3 = good, 2 = fair, and 1 = poor. Blood samples from the jugular vein and follicular fluid samples from the largest follicle were collected in order to perform hormone and metabolite assays. Environmental data were obtained from the local airport. There was a significant (P < .01) quadratic days pre- and postpartum by parity interaction for BCS. Body condition score for older cattle was the lowest at 90 d prior to calving and changed the least amount over time, while youngest cattle had the highest initial BCS at d 90 prior to calving and had the greatest change in BCS over time. Body condition score was the highest during summer calving season (3.3 ± .06) compared to BCS during winter calving season (2.6 ± .06). But the loss in BCS was greater for cows that calved in summer (-0.53 ± .06) compared to cows that calved in winter (-0.07 ± .08). Increased serum NEFA concentrations with simultaneous decreases in serum insulin concentrations for younger cattle implied a more negative EB status than for older cattle. The total number of follicles and total number of oocytes retrieved was significantly (P < .001) affected by a linear days postpartum by parity interaction with younger cattle having linear increases compared to decreases in the total number of follicles for older cattle. Oocyte quality score was affected by the quadratic days postpartum by parity interaction (P < .01) and calving season (P < .01). Younger cattle had higher initial quality scores compared to older cattle, but older cattle had higher quality oocytes towards the end of the 12 wk period compared with younger cattle. Younger cattle had higher E2 and IGF-I concentrations in follicular fluid associated with a higher number of total follicles and number of oocytes, compared to older cattle. However, oocyte quality of younger cattle seemed to be reduced and oocytes were less competent than for older cattle. Cattle in 3rd and greater lactation showed very little change in BCS and hormone and metabolite measures during early lactation, with no apparent decrease in oocyte quality, despite the aging effect on follicle numbers. This study demonstrated that conditions related to early lactation have a negative effect on oocyte quality and endocrine measures of dairy cattle and that animals of different ages are differentially affected. / Master of Science
42

Probing Novel Properties of Nucleons and Nuclei via Parity Violating Electron Scattering

Mercado, Luis Rafael 01 May 2012 (has links)
This thesis reports on two experiments conducted by the HAPPEx (Hall A Proton Parity Experiment) collaboration at the Thomas Jefferson National Accelerator Facility. For both, the weak neutral current interaction (WNC, mediated by the Z0 boson) is used to probe novel properties of hadronic targets. The WNC interaction amplitude is extracted by measuring the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons off unpolarized target hadrons. HAPPEx-III, conducted in the Fall of 2009, used a liquid hydrogen target at a momentum transfer of Q2 = 0.62 GeV2. The measured asymmetry was used to set new constraints on the contribution of strange quark form factors (GsE,M to the nucleon electromagnetic form factors. A value of APV = -23.803 +- 0.778 (stat) +- 0.359 (syst) ppm resulted in GEs + 0.517 GMs = 0.003 +- 0.010 (stat) +- 0.004 (syst) +- 0.009 (FF). PREx, conducted in the Spring of 2010, used a polarized electron beam on a 208Pb target at a momentum transfer of Q2 = 0.009 GeV2. This parity-violating asymmetry can be used to obtain a clean measurement of the root-mean-square radius of the neutrons in the 208Pb nucleus. The Z0 boson couples mainly to neutrons; the neutron weak charge is much larger than that of the proton. The value of this asymmetry is at the sub-ppm level and has a projected experimental fractional precision of 3%. We will describe the accelerator setup used to set controls on helicity-correlated beam asymmetries and the analysis methods for finding the raw asymmetry for HAPPEx-III. We will also discuss in some detail the preparations to meet the experimental challenges associated with measuring such a small asymmetry with the degree of precision required for PREx.
43

Parity Measurements on ²⁶Mg and ²⁸Si

Kieran, Michael Edward Joseph 05 1900 (has links)
An experiment is described whereby information can be gained concerning the parity of a state simply by the observation of that state. The result, based on the principles of parity conservation and time reversal invariance, is applied to measure parities of excited states in ²⁶Mg and ²⁸Si. / Thesis / Master of Science (MSc)
44

The (p,t) Reaction to Positive Parity States in 165Er

Stott, William 09 1900 (has links)
<p> Positive parity states in 165Er have been studied using the 167Er (p,t) 165Er reaction. The outgoing tritons were analyzed with a magnetic spectrograph at 13 angles between 6° and 70°. Two 7/2+ states at excitation energies of 63 and 465 keV were populated via ℓ≠0 transitions. Because of the lack of a pronounced minimum in the 1=0 angular distributions, some ℓ≠0 strength may contribute to the populating processes. Eight ℓ≠0 transitions were seen below 1 MeV excitation energy. A description of the observed positive parity levels has been attempted in the context of a Coriolis coupled Nilsson model calculation. </p> / Thesis / Master of Science (MSc)
45

The Effect of Regional Security Environments on State Attitudes Regarding the Use of Force and International Law: A Quantitative Analysis Utilizing International Positions on Operation Iraqi Freedom

Mason, Robert Wallace Jr. 24 May 2005 (has links)
The US-led war to oust the regime of Saddam Hussein elicited a wide range of responses among liberal states, from active diplomatic opposition in the prelude to war to actual combat support once hostilities commenced. These divergent responses, in part, reflected different perceptions of the legitimacy of force and international law. Furthermore, I contend that these perceptions are rooted in the unique regional security environment in which each state is situated, with states located in relatively insecure regional environments being more favorably disposed to view US military preponderance and use of force as a legitimate public good. Consequently, I hypothesize that the more insecure a state's regional security environment, the more likely it was to support, either diplomatically or militarily, the "major combat" phase of Operation Iraqi Freedom. To this end, I develop a measure of regional security based on concepts of power and polarity adapted from John Mearsheimer's The Tragedy of Great Power Politics. I then test this measure using a logistic regression analysis for 85 states located in 10 regions. The results indicate support for the hypothesis, but also illuminate the need for more research on the implications of power distributions within regional settings for international conflict in the post-Cold War era. / Master of Arts
46

Improve the Performance and Scalability of RAID-6 Systems Using Erasure Codes

Wu, Chentao 15 November 2012 (has links)
RAID-6 is widely used to tolerate concurrent failures of any two disks to provide a higher level of reliability with the support of erasure codes. Among many implementations, one class of codes called Maximum Distance Separable (MDS) codes aims to offer data protection against disk failures with optimal storage efficiency. Typical MDS codes contain horizontal and vertical codes. However, because of the limitation of horizontal parity or diagonal/anti-diagonal parities used in MDS codes, existing RAID-6 systems suffer several important problems on performance and scalability, such as low write performance, unbalanced I/O, and high migration cost in the scaling process. To address these problems, in this dissertation, we design techniques for high performance and scalable RAID-6 systems. It includes high performance and load balancing erasure codes (H-Code and HDP Code), and Stripe-based Data Migration (SDM) scheme. We also propose a flexible MDS Scaling Framework (MDS-Frame), which can integrate H-Code, HDP Code and SDM scheme together. Detailed evaluation results are also given in this dissertation.
47

Polarizace vakua v Coulombickém poli / Polarizace vakua v Coulombickém poli

Šimsa, Daniel January 2013 (has links)
In the present work the vacuum polarization and the circular dichroism of hydrogen-like atoms are studied. We derive equations for the Fourier transforma- tion of the vacuum expectation value of the charge density. We use it to derive Uehling potential and calculate energy shifts caused by it. Then we discuss effects of vacuum polarization in higher orders of α. In second part we define circular dichroism and we express it in terms of reduced matrix elements. Then we derive the formula for parity vilating potential which is generated by weak interaction and together with other results we use it to find the expression for circular dichro- ism in terms of hydrogen radial functions. 1
48

Dollarization and price dynamics

Peñaloza Pesantes, Roberto Vicente. January 2005 (has links)
Thesis (Ph. D. in Economics)--Vanderbilt University, Aug. 2005. / Title from title screen. Includes bibliographical references.
49

Posouzení vývoje úrokových sazeb a měnových kurzů vybraných zemí / Appraisal of the development of interest rates and exchange rates for selected countries

DRAHOŠOVÁ, Zuzana January 2016 (has links)
In the beginning this thesis deals with the theory of the exchange rate, its quotations, significance of its economic effect and ultimately the parity rate of interest, which is divided into a covered and an uncovered interest parity. It is followed by the methodology, which includes formulas and procedures used to achieve the aim. The most important part is the practical part, which deals with the general presentation of selected countries (Czech Republic, Republic of Poland, Hungary, Republic of Croatia and Romania) in terms of significant macroeconomic indicators and also shows the development of the exchange rates and interest rates in those countries. Subsequently, the thesis focuses on the verification of the uncovered interest parity by means of a graphical analysis, a regression analysis and a paired t-test. In view of results of these methods the conclusion was reached, that the theory has not been proven. The last two chapters describe the differences between the results of the selected countries and the possible reasons for the failure of the uncovered interest rate parity.
50

Corporate Tax Rates and the Purchasing Power Parity Doctrine

Ballard, Billy L. (Billy Lanoy) 08 1900 (has links)
This thesis analyzes the effect of corporate tax rates on the purchasing-power-parity (PPP) doctrine. The data used to test this hypothesis are drawn from the U. S., the U. K., the Federal Republic of Germany, Canada, and Japan. The first chapter introduces the reader to the concepts of the PPP doctrine and states the hypothesis. Chapter 2 reviews the literature on the PPP doctrine. Chapter 3 specifies a model of the PPP doctrine including tax rates. Chapter 4 reports and interprets the findings. The study is summarized and conclusions are drawn in chapter 5. In this study it is shown that tax rates are significant only in the case of the U. S. dollar/Canadian dollar exchange rate.

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