Performance evaluation of low environmental impact asphalt concretes using the mechanistic empirical design method based on laboratory fatigue and permanent deformation models

The "sustainability" concept relates to the prolonging of human economic systems with as little detrimental impact on ecological systems as possible. Construction that exhibits good environmental stewardship and practices that conserve resources in a manner that allow growth and development to be sustained for the long-term without degrading the environment are indispensable in a developed society. Past, current and future advancements in asphalt as an environmentally sustainable paving material are especially important because the quantities of asphalt used annually in Europe as well as in the U.S. are large. The asphalt industry is still developing technological improvements that will reduce the environmental impact without affecting the final mechanical performance. Warm mix asphalt (WMA) is a type of asphalt mix requiring lower production temperatures compared to hot mix asphalt (HMA), while aiming to maintain the desired post construction properties of traditional HMA. Lowering the production temperature reduce the fuel usage and the production of emissions therefore and that improve conditions for workers and supports the sustainable development. Even the crumb-rubber modifier (CRM), with shredded automobile tires and used in the United States since the mid 1980s, has proven to be an environmentally friendly alternative to conventional asphalt pavement. Furthermore, the use of waste tires is not only relevant in an environmental aspect but also for the engineering properties of asphalt [Pennisi E., 1992]. This research project is aimed to demonstrate the dual value of these Asphalt Mixes in regards to the environmental and mechanical performance and to suggest a low environmental impact design procedure. In fact, the use of eco-friendly materials is the first phase towards an eco-compatible design but it cannot be the only step. The eco-compatible approach should be extended also to the design method and material characterization because only with these phases is it possible to exploit the maximum potential properties of the used materials. Appropriate asphalt concrete characterization is essential and vital for realistic performance prediction of asphalt concrete pavements. Volumetric (Mix design) and mechanical (Permanent deformation and Fatigue performance) properties are important factors to consider. Moreover, an advanced and efficient design method is necessary in order to correctly use the material. A design method such as a Mechanistic-Empirical approach, consisting of a structural model capable of predicting the state of stresses and strains within the pavement structure under the different traffic and environmental conditions, was the application of choice. In particular this study focus on the CalME and its Incremental-Recursive (I-R) procedure, based on damage models for fatigue and permanent shear strain related to the surface cracking and to the rutting respectively. It works in increments of time and, using the output from one increment, recursively, as input to the next increment, predicts the pavement conditions in terms of layer moduli, fatigue cracking, rutting and roughness. This software procedure was adopted in order to verify the mechanical properties of the study mixes and the reciprocal relationship between surface layer and pavement structure in terms of fatigue and permanent deformation with defined traffic and environmental conditions. The asphalt mixes studied were used in a pavement structure as surface layer of 60 mm thickness. The performance of the pavement was compared to the performance of the same pavement structure where different kinds of asphalt concrete were used as surface layer. In comparison to a conventional asphalt concrete, three eco-friendly materials, two warm mix asphalt and a rubberized asphalt concrete, were analyzed. The First Two Chapters summarize the necessary steps aimed to satisfy the sustainable pavement design procedure. In Chapter I the problem of asphalt pavement eco-compatible design was introduced. The low environmental impact materials such as the Warm Mix Asphalt and the Rubberized Asphalt Concrete were described in detail. In addition the value of a rational asphalt pavement design method was discussed. Chapter II underlines the importance of a deep laboratory characterization based on appropriate materials selection and performance evaluation. In Chapter III, CalME is introduced trough a specific explanation of the different equipped design approaches and specifically explaining the I-R procedure. In Chapter IV, the experimental program is presented with a explanation of test laboratory devices adopted. The Fatigue and Rutting performances of the study mixes are shown respectively in Chapter V and VI. Through these laboratory test data the CalME I-R models parameters for Master Curve, fatigue damage and permanent shear strain were evaluated. Lastly, in Chapter VII, the results of the asphalt pavement structures simulations with different surface layers were reported. For each pavement structure, the total surface cracking, the total rutting, the fatigue damage and the rutting depth in each bound layer were analyzed.

Laboratory and field measurements of enantiomeric and non-enantiomeric biogenic VOCs and anthropogenic BTEX compounds

This doctoral thesis was focused on the investigation of enantiomeric and non-enantiomeric biogenic organic compound (BVOC) emissions from both leaf and canopy scales in different environments. In addition, the anthropogenic compounds benzene, toluene, ethylbenzene, and xylenes (BTEX) were studied. BVOCs are emitted into the lower troposphere in large quantities (ca. 1150 Tg C ·yr-1), approximately an order of magnitude greater than the anthropogenic VOCs. BVOCs are particularly important in tropospheric chemistry because of their impact on ozone production and secondary organic aerosol formation or growth. The BVOCs examined in this study were: isoprene, (-)/ (+)-α-pinene, (-)/ (+)-ß-pinene, Δ-3-carene, (-)/ (+)-limonene, myrcene, eucalyptol and camphor, as these were the most abundant BVOCs observed both in the leaf cuvette study and the ambient measurements. In the laboratory cuvette studies, the sensitivity of enantiomeric enrichment change from the leaf emission has been examined as a function of light (0-1600 PAR) and temperature (20-45°C). Three typical Mediterranean plant species (Quercus ilex L., Rosmarinus officinalis L., Pinus halepensis Mill.) with more than three individuals of each have been investigated using a dynamic enclosure cuvette. The terpenoid compound emission rates were found to be directly linked to either light and temperature (e.g. Quercus ilex L.) or mainly to temperature (e.g. Rosmarinus officinalis L., Pinus halepensis Mill.). However, the enantiomeric signature showed no clear trend in response to either the light or temperature; moreover a large variation of enantiomeric enrichment was found during the experiment. This enantiomeric signature was also used to distinguish chemotypes beyond the normal achiral chemical composition method. The results of nineteen Quercus ilex L. individuals, screened under standard conditions (30°C and 1000 PAR) showed four different chemotypes, whereas the traditional classification showed only two. An enclosure branch cuvette set-up was applied in the natural boreal forest environment from four chemotypes of Scots pine (Pinus sylvestris) and one chemotype of Norway spruce (Picea abies) and the direct emissions compared with ambient air measurements above the canopy during the HUMPPA-COPEC 2010 summer campaign. The chirality of a-pinene was dominated by (+)-enantiomers from Scots pine while for Norway spruce the chirality was found to be opposite (i.e. Abstract II (-)-enantiomer enriched) becoming increasingly enriched in the (-)-enantiomer with light. Field measurements over a Spanish stone pine forest were performed to examine the extent of seasonal changes in enantiomeric enrichment (DOMINO 2008). These showed clear differences in chirality of monoterpene emissions. In wintertime the monoterpene (-)-a-pinene was found to be in slight enantiomeric excess over (+)-a-pinene at night but by day the measured ratio was closer to one i.e. racemic. Samples taken the following summer in the same location showed much higher monoterpene mixing ratios and revealed a strong enantiomeric excess of (-)-a-pinene. This indicated a strong seasonal variance in the enantiomeric emission ratio which was not manifested in the day/night temperature cycles in wintertime. A clear diurnal cycle of enantiomeric enrichment in a-pinene was also found over a French oak forest and the boreal forest. However, while in the boreal forest (-)-a-pinene enrichment increased around the time of maximum light and temperature, the French forest showed the opposite tendency with (+)-a-pinene being favored. For the two field campaigns (DOMINO 2008 and HUMPPA-COPEC 2010), the BTEX were also investigated. For the DOMINO campaign, mixing ratios of the xylene isomers (meta- and para-) and ethylbenzene, which are all well resolved on the ß-cyclodextrin column, were exploited to estimate average OH radical exposures to VOCs from the Huelva industrial area. These were compared to empirical estimates of OH based on JNO2 measured at the site. The deficiencies of each estimation method are discussed. For HUMPPA-COPEC campaign, benzene and toluene mixing ratios can clearly define the air mass influenced by the biomass burning pollution plume from Russia.

Eliminating exposure to aqueous solvents is necessary for the early detection and ultrastructural elemental analysis of sites of calcium and phosphorus enrichment in mineralizing UMR106-01 osteoblastic cultures

The mechanism underlying the mineralization of bone is well studied and yet it remains controversial. Inherent difficulties of imaging mineralized tissues and the aqueous solubility of calcium and phosphate, the 2 ions which combine to form bone mineral crystals, limit current analyses of labile diffusible, amorphous, and crystalline intermediates by electron microscopy. To improve the retention of calcium and phosphorus, we developed a pseudo nonaqueous processing approach and used it to characterize biomineralization foci, extracellular sites of hydroxyapatite deposition in osteoblastic cell cultures. Since mineralization of UMR106-01 osteoblasts is temporally synchronized and begins 78 h after plating, we used these cultures to evaluate the effectiveness of our method when applied to cells just prior to the formation of the first mineral crystals. Our approach combines for the first time 3 well-established methods with a fourth one, i.e. dry ultrathin sectioning. Dry ultrathin sectioning with an oscillating diamond knife was used to produce electron spectroscopic images of mineralized biomineralization foci which were high-pressure frozen and freeze substituted. For comparison, cultures were also treated with conventional processing and wet sectioning. The results show that only the use of pseudo nonaqueous processing was able to detect extracellular sites of early calcium and phosphorus enrichment at 76 h, several hours prior to detection of mineral crystals within biomineralization foci.

A Method for Detecting Population Genetic Structure in Diverse, High Gene-Flow Species

Detecting small amounts of genetic subdivision across geographic space remains a persistent challenge. Often a failure to detect genetic structure is mistaken for evidence of panmixia, when more powerful statistical tests may uncover evidence for subtle geographic differentiation. Such slight subdivision can be demographically and evolutionarily important as well as being critical for management decisions. We introduce here a method, called spatial analysis of shared alleles (SAShA), that detects geographically restricted alleles by comparing the spatial arrangement of allelic co-occurrences with the expectation under panmixia. The approach is allele-based and spatially explicit, eliminating the loss of statistical power that can occur with user-defined populations and statistical averaging within populations. Using simulated data sets generated under a stepping-stone model of gene flow, we show that this method outperforms spatial autocorrelation (SA) and UST under common real-world conditions: at relatively high migration rates when diversity is moderate or high, especially when sampling is poor. We then use this method to show clear differences in the genetic patterns of 2 nearshore Pacific mollusks, Tegula funebralis (5 Chlorostoma funebralis) and Katharina tunicata, whose overall patterns of within-species differentiation are similar according to traditional population genetics analyses. SAShA meaningfully complements UST/FST, SA, and other existing geographic genetic analyses and is especially appropriate for evaluating species with high gene flow and subtle genetic differentiation.

Comparing the demonstration of freedom from Trichinella infection of domestic pigs by traditional and risk-based surveillance

Traditionally, the routine artificial digestion test is applied to assess the presence of Trichinella larvae in pigs. However, this diagnostic method has a low sensitivity compared to serological tests. The results from artificial digestion tests in Switzerland were evaluated over a time period of 15 years to determine by when freedom from infection based on these data could be confirmed. Freedom was defined as a 95% probability that the prevalence of infection was below 0.0001%. Freedom was demonstrated after 12 years at the latest. A new risk-based surveillance approach was then developed based on serology. Risk-based surveillance was also assessed over 15 years, starting in 2010. It was shown that by using this design, the sample size could be reduced by at least a factor of 4 when compared with the traditional testing regimen, without lowering the level of confidence in the Trichinella-free status of the pig population.

An Investigation On The Use Of Microalgae For Biogas Enrichment

There is a need for biomethane capture and carbon dioxide sequestration to mitigate evident global climate change. This research work investigated the potential for microalgae to remove CO2 from biogas as a biotechnical method for upgrading the thermal value for subsequent compression, liquification, or introduction to natural gas pipelines. Because biogas is largely methane, the effect of high methane environments on mixed microalgae was explored and found that specific carbon utilization rates were not statistically different when microalgae were exposed to biogas environments (70% v/v CH4) , relative to high CO2 environment. The uses of conventional bubbled column photobioreactors (PBR) were assessed for CO2 removal and subsequent CH4 enrichment. A continuously-bubbled biogas PBR (cB-PBR5) and intermittently-bubbled biogas PBR (iB-PBR) experienced CO2 loading rates of about 1664 and 832 mg C/L*day and showed 30.0 and 60.1 % carbon removal, respectively. However, a lack of biogas enrichment and issues associated growth inhibition due to high CO2 environments as well as stripping the dissolved gases, namely oxygen and nitrogen, from the bulk liquid and introduction to the outlet gas prompted the consideration for gas/liquid separation using nonporous hollow-fiber (HF) membranes for CO2 transfer. The potential for two non-porous HF membrane materials [polydimethylsiloxane (PDMS) and composite polyurethane (PU)] were modeled along fiber length using a mechanistic model based on polymeric material transport properties (Gilmore et al., 2009). Based on a high CO2:CH4 permeability selectivity for PU of 76.2 the model predicted gas enrichment along an 8.5 cm fiber length. Because PDMS permeability selectivity is low (3.5), evident gas transfer was not predicated along a 34.3 cm length. Both of these HF materials were implemented in hollow-fiber membrane-carbonated biofilm (HFMcB) PBRs for microalgal-mediated biogas enrichment. Phototrophic biofilm colonization occurred on the membrane, where CO2 concentration was greatest. The presence of a biofilm demonstrated greater resiliency to high CO2 environments, compared to the conventional PBRs. However, as the PDMS model predicted, the PDMS HFMcBs did not demonstrate gas enrichment. These reactors received CO2 loading rates of 200 mg C/L*day based on PDMS permeability flux and showed approximately 65% removal of the total C transferred across the membrane. Thus, the HFMcBs demonstrated controlled carbonation of the bulk liquid via a nonporous HF membrane. Likewise, the experimental PU HFMcB did not show gas enrichment yet this result should be further explored due to the high permeability selectivity of the polymeric material. Chemical stratifications, namely pH and dissolved O2, present in a PDMS membrane-carbonated biofilm were analyzed using electrochemical microsensors. Results indicated that high DO (20 mg L-1) exists at surface of the biofilm where light availability is greatest and low pH microenvironments (pH=5.40) exist deep in the biofilm where the diffusive flux of CO2 drives transfer through the biofilm. The presence of a 400-600 ¿m liquid phase boundary layer was evident from microsensor profiles. Cryosectioning of the biofilm samples showed the biofilm to be approximately 1.17 ± 0.07 mm thick, suggesting that the high localized concentration of biomass associated with the phototrophic biofilm aided in overcoming inhibition in a microenvironment dominated by CO2(aq). Challenges of biofilm detachment and PBR fouling as well as microalgal growth inhibition in the presence of high CO2 content remain for applications of microalgae for biogas enrichment.

Medication errors in a swiss cardiovascular surgery department: a cross-sectional study based on a novel medication error report method

The purpose of this study was (1) to determine frequency and type of medication errors (MEs), (2) to assess the number of MEs prevented by registered nurses, (3) to assess the consequences of ME for patients, and (4) to compare the number of MEs reported by a newly developed medication error self-reporting tool to the number reported by the traditional incident reporting system. We conducted a cross-sectional study on ME in the Cardiovascular Surgery Department of Bern University Hospital in Switzerland. Eligible registered nurses (n = 119) involving in the medication process were included. Data on ME were collected using an investigator-developed medication error self reporting tool (MESRT) that asked about the occurrence and characteristics of ME. Registered nurses were instructed to complete a MESRT at the end of each shift even if there was no ME. All MESRTs were completed anonymously. During the one-month study period, a total of 987 MESRTs were returned. Of the 987 completed MESRTs, 288 (29%) indicated that there had been an ME. Registered nurses reported preventing 49 (5%) MEs. Overall, eight (2.8%) MEs had patient consequences. The high response rate suggests that this new method may be a very effective approach to detect, report, and describe ME in hospitals.

Glacier mass balance reconstruction by sublimation induced enrichment of chemical species on Cerro Tapado (Chilean Andes)

A 36 m long ice core down to bedrock from the Cerro Tapado glacier (5536 m a.s.l, 30°08' S, 69°55' W) was analyzed to reconstruct past climatic conditions for Northern Chile. Because of the marked seasonality in the precipitation (short wet winter and extended dry summer periods) in this region, major snow ablation and related post-depositional processes occur on the glacier surface during summer periods. They include predominantly sublimation and dry deposition. Assuming that, like measured during the field campaign, the enrichment of chloride was always related to sublimation, the chemical record along the ice core may be applied to reconstruct the history of such secondary processes linked to the past climatic conditions over northern Chile. For the time period 1962–1999, a mean annual net accumulation of 316 mm water equivalent (weq) and 327 mm weq loss by sublimation was deduced by this method. This corresponds to an initial total annual accumulation of 539 mm weq. The annual variability of the accumulation and sublimation is related with the Southern Oscillation Index (SOI): higher net-accumulation during El-Niño years and more sublimation during La Niña years. The deepest part of the ice record shows a time discontinuity; with an ice body deposited under different climatic conditions: 290 mm higher precipitation but with reduced seasonal distribution (+470 mm in winter and –180 mm in summer) and –3°C lower mean annual temperature. Unfortunately, its age is unknown. The comparison with regional proxy data however let us conclude that the glacier buildup did most likely occur after the dry mid-Holocene.

GENE SET ENRICHMENT ANALYSIS MADE SIMPLE

Among the many applications of microarray technology, one of the most popular is the identification of genes that are differentially expressed in two conditions. A common statistical approach is to quantify the interest of each gene with a p-value, adjust these p-values for multiple comparisons, chose an appropriate cut-off, and create a list of candidate genes. This approach has been criticized for ignoring biological knowledge regarding how genes work together. Recently a series of methods, that do incorporate biological knowledge, have been proposed. However, many of these methods seem overly complicated. Furthermore, the most popular method, Gene Set Enrichment Analysis (GSEA), is based on a statistical test known for its lack of sensitivity. In this paper we compare the performance of a simple alternative to GSEA.We find that this simple solution clearly outperforms GSEA.We demonstrate this with eight different microarray datasets.

Virus isolation vs RT-PCR: which method is more successful in detecting VHSV and IHNV in fish tissue sampled under field conditions?

This study compared the results of reverse transcription-polymerase chain reaction (RT-PCR) and traditional virus isolation on cell culture in detection of viral haemorrhagic septicaemia virus (VHSV) and infectious haematopoietic necrosis virus (IHNV). RT-PCR was used for 172 tissue sample pools (total of 859 fish) originating from a field survey on the occurrence of VHSV and IHNV in farmed and wild salmonids in Switzerland. These samples represented all sites with fish that were either identified as virus-positive by means of virus isolation (three sites, four positive tissue sample pools) and/or demonstrated positive anti-VHSV-antibody titres (83 sites, 121 positive blood samples) in a serum plaque neutralization test (SPNT). The RT-PCR technique confirmed the four VHSV-positive tissue sample pools detected by virus isolation and additionally identified one VHSV-positive sample that showed positive anti-VHSV-AB titres, but was negative in virus isolation. With IHNV, RT-PCR detected two positive samples not identified by virus isolation while in these fish the SPNT result had been questionable. One of the IHNV-positive samples represents the first detection of IHNV-RNA in wild brown trout in Switzerland. Compared to SPNT, the RT-PCR method detected, as with virus isolation, a much lower number of positive cases; reasons for this discrepancy are discussed. Our results indicate that RT-PCR can not only be successfully applied in field surveys, but may also be slightly more sensitive than virus isolation. However, in a titration experiment under laboratory conditions, the sensitivity of RT-PCR was not significantly higher when compared with virus isolation.

Non-invasive method to predict viscosity and size using total internal reflection fluorescence microscopy (TIRFM) system

This study develops an automated analysis tool by combining total internal reflection fluorescence microscopy (TIRFM), an evanescent wave microscopic imaging technique to capture time-sequential images and the corresponding image processing Matlab code to identify movements of single individual particles. The developed code will enable us to examine two dimensional hindered tangential Brownian motion of nanoparticles with a sub-pixel resolution (nanoscale). The measured mean square displacements of nanoparticles are compared with theoretical predictions to estimate particle diameters and fluid viscosity using a nonlinear regression technique. These estimated values will be confirmed by the diameters and viscosities given by manufacturers to validate this analysis tool. Nano-particles used in these experiments are yellow-green polystyrene fluorescent nanospheres (200 nm, 500 nm and 1000 nm in diameter (nominal); 505 nm excitation and 515 nm emission wavelengths). Solutions used in this experiment are de-ionized (DI) water, 10% d-glucose and 10% glycerol. Mean square displacements obtained near the surface shows significant deviation from theoretical predictions which are attributed to DLVO forces in the region but it conforms to theoretical predictions after ~125 nm onwards. The proposed automation analysis tool will be powerfully employed in the bio-application fields needed for examination of single protein (DNA and/or vesicle) tracking, drug delivery, and cyto-toxicity unlike the traditional measurement techniques that require fixing the cells. Furthermore, this tool can be also usefully applied for the microfluidic areas of non-invasive thermometry, particle tracking velocimetry (PTV), and non-invasive viscometry.

Traditional lesion detection aids

Lesion detection aids ideally aim at increasing the sensitivity of visual caries detection without trading off too much in terms of specificity. The use of a dental probe (explorer), bitewing radiography and fibre-optic transillumination (FOTI) have long been recommended for this purpose. Today, probing of suspected lesions in the sense of checking the 'stickiness' is regarded as obsolete, since it achieves no gain of sensitivity and might cause irreversible tooth damage. Bitewing radiography helps to detect lesions that are otherwise hidden from visual examination, and it should therefore be applied to a new patient. The diagnostic performance of radiography at approximal and occlusal sites is different, as this relates to the 3-dimensional anatomy of the tooth at these sites. However, treatment decisions have to take more into account than just lesion extension. Bitewing radiography provides additional information for the decision-making process that mainly relies on the visual and clinical findings. FOTI is a quick and inexpensive method which can enhance visual examination of all tooth surfaces. Both radiography and FOTI can improve the sensitivity of caries detection, but require sufficient training and experience to interpret information correctly. Radiography also carries the burden of the risks and legislation associated with using ionizing radiation in a health setting and should be repeated at intervals guided by the individual patient's caries risk. Lesion detection aids can assist in the longitudinal monitoring of the behaviour of initial lesions.

A new sensitive method for the quantification of glyoxal and methylglyoxal in snow and ice by stir bar sorptive extraction and liquid desorption-HPLC-ESI-MS

In this study, the development of a new sensitive method for the analysis of alpha-dicarbonyls glyoxal (G) and methylglyoxal (MG) in environmental ice and snow is presented. Stir bar sorptive extraction with in situ derivatization and liquid desorption (SBSE-LD) was used for sample extraction, enrichment, and derivatization. Measurements were carried out using high-performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). As part of the method development, SBSE-LD parameters such as extraction time, derivatization reagent, desorption time and solvent, and the effect of NaCl addition on the SBSE efficiency as well as measurement parameters of HPLC-ESI-MS/MS were evaluated. Calibration was performed in the range of 1–60 ng/mL using spiked ultrapure water samples, thus incorporating the complete SBSE and derivatization process. 4-Fluorobenzaldehyde was applied as internal standard. Inter-batch precision was <12 % RSD. Recoveries were determined by means of spiked snow samples and were 78.9 ± 5.6 % for G and 82.7 ± 7.5 % for MG, respectively. Instrumental detection limits of 0.242 and 0.213 ng/mL for G and MG were achieved using the multiple reaction monitoring mode. Relative detection limits referred to a sample volume of 15 mL were 0.016 ng/mL for G and 0.014 ng/mL for MG. The optimized method was applied for the analysis of snow samples from Mount Hohenpeissenberg (close to the Meteorological Observatory Hohenpeissenberg, Germany) and samples from an ice core from Upper Grenzgletscher (Monte Rosa massif, Switzerland). Resulting concentrations were 0.085–16.3 ng/mL for G and 0.126–3.6 ng/mL for MG. Concentrations of G and MG in snow were 1–2 orders of magnitude higher than in ice core samples. The described method represents a simple, green, and sensitive analytical approach to measure G and MG in aqueous environmental samples.

Rapid method to express and purify human membrane protein using the Xenopus oocyte system for functional and low-resolution structural analysis.

Progress toward elucidating the 3D structures of eukaryotic membrane proteins has been hampered by the lack of appropriate expression systems. Recent work using the Xenopus oocyte as a novel expression system for structural analysis demonstrates the capability of providing not only the significant amount of protein yields required for structural work but also the expression of eukaryotic membrane proteins in a more native and functional conformation. There is a long history using the oocyte expression system as an efficient tool for membrane transporter and channel expression in direct functional analysis, but improvements in robotic injection systems and protein yield optimization allow the rapid scalability of expressed proteins to be purified and characterized in physiologically relevant structural states. Traditional overexpression systems (yeast, bacteria, and insect cells) by comparison require chaotropic conditions over several steps for extraction, solubilization, and purification. By contrast, overexpressing within the oocyte system for subsequent negative-staining transmission electron microscopy studies provides a single system that can functionally assess and purify eukaryotic membrane proteins in fewer steps maintaining the physiological properties of the membrane protein.

Traditional linkage analysis in admixed families

Currently there is no general method to study the impact of population admixture within families on the assumptions of random mating and consequently, Hardy-Weinberg equilibrium (HWE) and linkage equilibrium (LE) and on the inference obtained from traditional linkage analysis. ^ First, through simulation, the effect of admixture of two populations on the log of the odds (LOD) score was assessed, using Prostate Cancer as the typical disease model. Comparisons between simulated mixed and homogeneous families were performed. LOD scores under both models of admixture (within families and within a data set of homogeneous families) were closest to the homogeneous family scores of the population having the highest mixing proportion. Random sampling of families or ascertainment of families with disease affection status did not affect this observation, nor did the mode of inheritance (dominant/recessive) or sample size. ^ Second, after establishing the effect of admixture on the LOD score and inference for linkage, the presence of induced disequilibria by population admixture within families was studied and an adjustment procedure was developed. The adjustment did not force all disequilibria to disappear but because the families were adjusted for the population admixture, those replicates where the disequilibria exist are no longer affected by the disequilibria in terms of maximization for linkage. Furthermore, the adjustment was able to exclude uninformative families or families that had such a high departure from HWE and/or LE that their LOD scores were not reliable. ^ Together these observations imply that the presence of families of mixed population ancestry impacts linkage analysis in terms of the LOD score and the estimate of the recombination fraction. ^