Cryopreservation of germplasm is widely used in agriculture, biotechnology, conservation of threatened species and human reproductive medicine. There is a need however to improve the reproductive efficiency of breeding with cryopreserved semen, which may involve increasing the post-thaw quality of sperm through improvements in cryopreservation extenders. Extenders including egg yolk from chickens are successfully used worldwide for cryopreservation of bovine semen, whereas the protective agent in the egg yolk is believed to be the low-density lipoprotein (LDL) fraction. Egg yolks of different avian species vary in their cholesterol, phospholipid and polyunsaturated fatty acid content which have been shown to have important effects on sperm’s freezing capability. The purpose of this study was to determine the cryoprotective effect of clarified egg yolk and LDLs extracted from different egg yolk sources (chicken, chicken omega-3, pigeon, quail and turkey) on bovine sperm. Semen from six bulls was collected four times each by electroejaculation, split and diluted with the 10 following extenders: chicken clarified (Ccl), chicken omega-3 clarified (O3cl), pigeon clarified (Pcl), quail clarified (Qcl), turkey clarified (Tcl), chicken LDL (CLDL), chicken omega-3 LDL (O3LDL), pigeon LDL (PLDL), quail LDL (QLDL) and turkey LDL (TLDL). The extended semen was evaluated, cryopreserved and examined directly after thawing (0h) and after two hours at 37 ˚C (2h). Computer assisted sperm analysis (CASA) was used to determine total sperm motility (TM), progressive motility (PM), straight line velocity (VSL), curvilinear velocity (VCL) and average path velocity (VAP). Intact plasma membrane (IPM) and intact acrosomes (IA) were measured by flow cytometry. The percentage change (loss; Δ%) of each sperm characteristic was calculated and used to compare the effect of the extenders. From extending to 0h post-thaw, the pigeon LDL extender lead to greater losses in sperm total and progressive motility, as well as of intact acrosomes, than the other nine extenders tested (P < 0.05). During 0h to 2h post-thaw, the sperm in PLDL extender experienced greater losses in total and progressive motility (P < 0.0001), as well as in curvilinear velocity (P < 0.05), than in all the other nine extenders. Sperm in turkey clarified extender had a greater loss in the velocity parameters (VSL, VAP, VCL) than sperm in several of the other extenders such as O3cl, CLDL, O3LDL, QLDL and TLDL from 0h to 2h (P < 0.05). Concomitantly, sperm in the Tcl extender had a greater loss in the velocity parameters and of intact acrosomes compared to sperm in its counterpart, the turkey LDL extender, from 0h to 2h post-thaw (P < 0.05). The differences produced in post-thaw quality of cryopreserved bovine sperm in the pigeon LDL and turkey clarified extenders were attributed to methodological differences in these egg yolk preparations compared with the other eight extenders. Importantly, the results demonstrate that with most egg yolk preparations derived from a variety of species, there are equivalent cryoprotective effects afforded by the use of omega-3 chicken, pigeon, quail, or conventional chicken egg yolk in a clarified form in freezing extenders for bovine semen. We further proved that the freezing capabilities of bovine semen extenders containing the low-density lipoprotein fraction of omega-3 chicken, quail, turkey and conventional chicken egg yolk were similar.

Canadian grown oilseed flax is known for its oils that are used for industrial products. The flax fiber may also have a use as a potential replacement for synthetic fibers as reinforcement in plastic composites. It can also be utilized as a cost effective and environmentally acceptable supplement in the biodegradable composites. Tire rubber is a complex material which does not decompose naturally. As a result, many researchers have been trying to develop new applications for recycling scrap tires. The conversion of flax straw and scrap tire into a profitable product may benefit the agricultural economy, tire recycling market, and our environment. The main goal of this research was to develop a biocomposite material containing recycled ground tire rubber (GTR), untreated flax fiber, and linear low-density polyethylene (LLDPE).<p> In this study, the new biocomposite material was successfully prepared from flax fiber/shives, GTR, and LLDPE through extrusion and compression molding processes. The composites were compounded through a single-screw extruder. Then the pelletized extrudates were hot pressed into the final biocomposites. The properties of the flax fiber-GTR-LLDPE biocomposites were defined by using tearing, tensile, water absorption, hardness, and differential scanning calorimetry (DSC) tests. The effects of the independent variables (flax fiber content and GTR-LLDPE ratio) on each of the dependent variables (tear strength from tearing test, tensile yield strength and Youngs modulus from tensile test, and weight increase from water absorption test) were modeled. The properties of the composites can be predicted by using the mathematical model with known flax fiber content and GTR-LLDPE ratio.<p> The tensile yield strength and stiffness of the biocomposite were improved with the addition of flax fiber. The optimal composition of the biocomposite material (with strongest tensile yield strength or highest Youngs modulus) was calculated by using the model equations. The maximum yield strength was found to exist for a flax fiber content of 10.7% in weight and GTR-LLDPE ratio of one. The largest Youngs modulus was found for a fiber content of 17.7% by weight and the same GTR-LLDPE ratio. Both of these fiber contents were less than the amount that would give a composite with a 2% weight increase in water absorption.

In this thesis, we extend applications of Low-Density Parity-Check (LDPC) codes to a combination of constituent sub-channels, which is a mixture of Gaussian channels with erasures. This model, for example, represents a common channel in magnetic recordings where thermal asperities in the system are detected and represented at the decoder as erasures. Although this channel is practically useful, we cannot find any previous work that evaluates performance of LDPC codes over this channel. We are also interested in practical issues such as designing robust LDPC codes for the mixture channel and predicting performance variations due to erasure patterns (random and burst), and finite block lengths. On time varying channels, a common error control strategy is to adapt the coding rate according to available channel state information (CSI). An effective way to realize this coding strategy is to use a single code and puncture it in a rate-compatible fashion, a so-called rate-compatible punctured code (RCPC). We are interested in the existence of good puncturing patterns for rate-changes that minimize performance loss. We show the existence of good puncturing patterns with analysis and verify the results with simulations. Universality of a channel code across a broad range of coding rates is a theoretically interesting topic. We are interested in the possibility of using the puncturing technique proposed in this thesis for designing universal LDPC codes. We also consider how to design high rate LDPC codes by puncturing low rate LDPC codes. The new design method can take advantage of longer effect block lengths, sparser parity-check matrices, and larger minimum distances of low rate LDPC codes.

A circuit design of Low Density Parity Check (LDPC) decoder for IEEE 802.16e systems is with new overlapped method is proposed in this thesis. This circuit can be operated with 19 modes which are corresponding to block sizes of 576, ¡K, 2304. LDPC decoders can be implemented by using iterations with Variable Node and Check Node Processes. The hardware utilization ratio, which can be enhanced from 50% to 100% by using our proposed overlapped method, is better than traditional overlapped method. In [2], the traditional overlapped method utilization ratio just can be enhanced from 50% to 75% for IEEE 802.16e LDPC decoder with code rate 1/2. Under the same operating frequency, our proposed method can further increase 25% when compared with traditional overlapped method [2]. In this thesis, we also propose two circuit architectures to increase the operating frequency. First, we use a faster comparison circuit in our comparison unit [1]. Second, we use Carry Save Adder¡]CSA¡^method [8] to replace the common adder unit. The circuit is carried out by TSMC CMOS 0.18£gm 1P6M process with chip area 3.11 x 3.08 mm2. In the gate level simulation, the output data rate of this circuit is above 78.4MHz, so the circuit can meet the requirement of IEEE 802.16e system.

Cooperative communication has been shown that it is an effective way to combat the outage caused by channel fading; that is, it provides the spatial diversity for communication. Except for amplify-and-forward (AF) and decode-and-forward (DF), compressed-and-forward (CF) is also an efficient forwarding strategy. In this thesis, we proposed a new CF scheme. In the existing CF protocol, the relay will switch to the DF mode when the source transmitted signal can be recovered by the relay completely; no further compression is made in this scheme. In our proposed, the relay will estimate if the codeword in a block is succeeded decoded, choose the corresponding forwarding methods with LDPC coding; those are based on joint source-channel coding or compressive sensing. At the decode side, a joint decoder with side information that performs sum-product algorithm (SPA) to decode the source message. Simulation results show that the proposed CF scheme can acquire the spatial diversity and outperform AF and DF schemes.

Predominance of small dense Low Density Lipoprotein (LDL) is associated with a two to threefold increase in risk for Coronary Heart Disease (CVD). Small, dense HDL (High Density Lipoprotein) particles protect small dense LDL from oxidative stress. Technological advancements have introduced an array of techniques for measuring diameters of LDL and HDL as well as estimating overall particle heterogeneity. However, there is lack of comparative studies between these techniques, and, hence, no conclusive evidence to establish the merits of one method relative to others. The primary purpose of this study was to compare Nondenaturing Gradient Gel Electrophoresis (NDGGE) and Dynamic Laser Light Scattering (DLLS) methods in determining LDL and HDL particle diameter. Our comparison entailed: 1) Evaluating the two methods in terms of their reproducibility 2) Correlating the two methods(in future studies method selection would be driven by time and cost considerations if the two methods correlate), and 3) Evaluating the two methods in terms of their ability to identify bi-modal samples. A secondary purpose of this research was to investigate the effect of refrigerated plasma storage on particle diameter. Reproducibility was measured as Coefficient of Variance (CV). Within and between runs, CV for LDL and HDL for NDGGE were <6% and <15%, respectively and for DLLS, CV within runs were <3% and <5.5%, respectively. No correlation was observed between LDL diameter from the two methods. NDGGE showed two bands for 157 HDL samples of which only 24 samples showed bimodal peaks in DLLS. In order to study the effect of storage, three sample sets of LDL and two sample sets of HDL were used. NDGGE showed a significant difference between mean diameter of fresh and stored LDL and HDL sample for all sets, whereas DLLS showed a significant difference in only one LDL sample set and none for HDL sample sets. We conclude that DLLS may be a better method for measuring LDL diameter because NDGGE overestimated LDL diameter. However, NDGGE was able to resolve subpopulation better in an HDL sample than DLLS. Thus, NDGGE may be a better choice for measuring HDL diameter than DLLS.

With the enormous growing applications of mobile communications, how to reduce the power dissipation of wireless communication has become an important issue that attracts much attention. One of the key techniques to achieve low power transmission is to develop a powerful channel coding scheme which can perform good error correcting capability even at low signal-to-noise ratio. In recent years, the trend of the error control code development is based on the iterative decoding algorithm which can lead to higher coding gain. Especially, the rediscovery of the low-density parity-check code ¡]LDPC¡^has become the most famous code after the introduction of Turbo code since it is the code closest to the well-know Shannon limit. However, since the block size used in LDPC is usually very large, and the parity matrix used in LDPC is quite random, the hardware implementation of LDPC has become very difficult. It may require a significant number of arithmetic units as well as very complex routing topology. Therefore, this thesis will address several design issues of LDPC decoder. First, under no SNR estimation condition, some simulation results of several LDPC architectures are provided and have shown that some architectures can achieve close performance to those with SNR estimation. Secondly, a novel message quantization method is proposed and applied in the design LDPC to reduce to the memory and table sizes as well as routing complexity. Finally, several early termination schemes for LDPC are considered, and it is found that up to 42% of bit node operation can be saved.

The aim of this study is to investigate the effects of compatibilizers, fumed silica and mixing order of components on morphological, thermal, mechanical and flow properties of LDPE/Fumed silica nanocomposites. As compatibilizer(Co) / ethylene/n-butyl acrylate/maleic anhydride (E-nBA-MAH), ethylene/glycidyl methacrylate (E-GMA) and ethylene/methyl acrylate/glycidyl methacrylate (E-MA-GMA) Lotader&reg / resins / as silica Cab-o-sil&reg / M5 fumed silica were used. All samples were prepared by means of a lab scale co-rotating twin screw extruder and injection molded into standard samples. In the first step, individual effects of filler and compatibilizers were studied in binary systems with LDPE. Then, keeping the amount of compatibilizer constant at 5%, ternary nanocomposites were prepared by adding 2 or 5% of fumed silica using different component mixing orders. Among investigated mixing orders, mechanical test results showed that the best sequences of component addition are FO1 [(LDPE+Co)+M5] and FO2 [(LDPE+M5)+Co] mixing orders. Considering the compatibilizers, E-nBA-MAH terpolymer showed the highest performance in improving the mechanical properties, E-GMA copolymer also gave satisfactory results. According to the DSC analysis, since addition of fumed silica and compatibilizer does not influence the crystallization behavior of the compositions, it is concluded that, neither fumed silica nor any of the compatibilizers have nucleation activity on LDPE. MFI test results showed that, addition of fumed silica increases the melt viscosity, decreasing MFI values of samples. This change seems to be directly proportional to fumed silica amount.

The objective of this study is to investigate the effects of titanate coupling agents on low density polyethylene (LDPE) and polypropylene (PP) blends and composites in terms of their mechanical and morphological properties. PP and LDPE composites were produced separately in a Brabender internal mixer, and CaCO3 was used as inorganic filler with compositions of 20, 40 and 60 %. PP/LDPE blends were produced in a twin-screw extruder with ratios of 75/25, 50/50 and 25/75. Their composites were prepared with addition of untreated and titanate-treated CaCO3 at 20% filler content. Titanate coupling agent which is appropriate for LDPE, PP and CaCO3 was used to improve the mechanical properties of the blends and composites. For this purpose, &ldquo / Lica 12&rdquo / which is a kind of neoalkoxy organotitanate was used. Two forms of Lica 12 were used: powder form (Capow L12) and pellet form (Caps L12). Samples with and without titanate were prepared and then they were injection molded to make specimens for tensile and impact tests. Tensile fracture surfaces of samples were examined by scanning electron microscopy (SEM). Their mechanical and morphological properties were compared with each other to determine the effects of Lica 12. This study showed that Capow L12 improved strain at break and impact strength of PP/CaCO3 composites and PP/LDPE blends containing 75% and 50% PP. The strain at break value of of PP75 composite with 20% titanate-treated filler increased significantly up to 509% which is the highest value among all blends and composites in this study. Capow L12 exhibited its functions in PP matrix much more effectively than in LDPE matrix.

Thesis (M.Sc.), Memorial University of Newfoundland, 2000. / Restricted until June 2003. Bibliography: leaves 98-117.