There is a growing recognition that conservation programs using hatchery-reared fish should strive to produce individuals that represent phenotypes present in natural environments. Size variability within cohorts, mediated through inter-individual differences in growth rates, provides one avenue by which phenotype can be studied. High growth rates are generally equated with greater fitness. However, there is evidence that fish with slower relative growth and smaller sizes continue to persist within populations. This thesis aimed to better understand the causes and potential implications of variable sizes and growth rates on the potential recruitment of hatchery-reared Lake Sturgeon, Acipenser fulvescens. Studies were developed to 1) determine the mechanisms behind these observed variations and 2) assess the behavioural and physiological consequences of being either a fast- or slow-grower (i.e., large or small). Laboratory studies concluded that external factors, most notably the presence of conspecifics during feeding events, influenced size variability more than inherent predispositions towards faster or slower growth. Examination of size-dependent versus size-independent feeding interactions further confirmed that variability does not appear to be the result of underlying fixed behaviours. The consequence of slower growth rates and smaller sizes did not lead to higher mortality or reduced body condition during a low temperature challenge. Recapture rates and downstream movements following stocking events of both young-of-the-year (YOY) and yearling Lake Sturgeon in the Winnipeg River, Manitoba could not be correlated to inter-individual differences in size. Although initial study on the cause of growth and size divergence may lead one to conclude that slow-growing (i.e., small) Lake Sturgeon represent a substandard phenotype, subsequent studies could not point to inferior performance of these individuals when compared to faster-growing (i.e., large) individuals of the same age. As such, the practice of size-selection for relatively faster-growing and larger individuals in future Lake Sturgeon enhancement programs is discouraged, at least until there are more conclusive findings to suggest otherwise. Future studies should continue to look at recruitment in relation to growth rate and size among naturally produced Lake Sturgeon juveniles in order to put the results of this research into context.

This study investigated how varying the required force level and the direction of force change produced by the thumb and index finger affect the accuracy and variability of a cyclic isometric pinch force-tracking task. Accuracy was examined by both absolute error and relative error for the minimum and maximum force levels and by root mean square error (RMSE) and normalized root mean square error (normalized RMSE) for the force direction reversals. Variability was represented by coefficient of variation of error (CVE). In this study, ‘maximum force’ was defined as the highest force level of a given target force range, and ‘minimum force’ was defined as the minimum force level of the target range. In addition, ‘force increasing to decreasing’ indicated that the track ball motion changed from increasing to decreasing, requiring the performer to exert increasing force up to the maximum force level and then decreasing force to follow the track ball moving toward the minimum force level. The phrase ‘force decreasing to increasing’ indicated the opposite force direction reversal. Eighteen healthy right handed adult volunteers (nine men and nine women; mean age ± SD, 28.3±1.22 and 26.4±1.74) participated in this study. The participants performed a cyclic isometric pinch force tracking task over three different force ranges. Force range 1 was from a minimum force of 3% of maximal voluntary contraction force (MVC) to a maximum force of 6% MVC. In force range 2, the range was from 6% to 12% MVC, and force range 3 was from 12% to 24% MVC. For each force range, five practice trials and ten actual test trials were performed. Rest periods of twenty seconds between trials and one minute between sets of trials (including between practice and actual test trials) were provided to minimize fatigue effects. Absolute error uniformly increased as a function of increasing force. However, the 3% target force level showed larger relative error compared to the 12% target force level (p < 0.05). Another finding of this study was that producing forces positioned at the minimum target level in a range yielded higher absolute error and relative error compared to the same forces when placed at the maximum target level of a different force range. In terms of the reversals, RMSE values were higher at the change from force deceasing to increasing than the opposite, as well as at higher force levels, while normalized RMSE values were greater at lower force levels. CVE was not significantly different between the two reversals in this study. This might indicate that poorer performance during the change from force decreasing to increasing could originate from the effort to maintain consistent performance and additional effort was not beneficial to increase accuracy for the change from force decreasing to increasing. / text

This project shows a design for a low power and low noise analog front end for a heart variability sensor. Chopper Stabilization is a well known technique for reducing noise of an amplifier and is used to reduce the noise in the Instrumentation Amplifier in this project. A d/dt peak detector is used to find the peaks of the heart beats. Low power, low noise heart variability sensors can look for patterns in a patient’s heart beat which can be correlated to known patterns for certain diseases. This can help doctors determine a patient’s susceptibility to these disease and prescribe preventitive treatment in advance / text

Palaeoclimate reconstruction is of paramount importance because the more we know about the patterns of past variability the better we understand the present climate. Precipitation is a key climate variable shaping the culture and economy of China. However, few studies are concerned with past changes in precipitation. The existing few are either reconstructed by one reconstruction approach or based on a single proxy, limiting reconstructions to a small region and a short period of time. The study presents the first high-resolution multi-proxy palaeoprecipitation reconstruction of China as a whole. Proxies used in the study are of annual-to-decadal resolution, mainly including historical written evidence, tree-ring chronologies and stable isotopic records. In accordance with the principle of “uniformity in the nature”, about 80 proxy series extend the precipitation records as far back in time as 2,000 years ago when there was a significant increase in natural proxy and documentary records of climate all over China. The top three popular reconstruction approaches are borrowed from multi-proxy temperature reconstructions to reconstruct the palaeoprecipitation. A pioneering attempt is taken to evaluate and compare these approaches in reconstructing precipitation over a long term in a large scale. The three common practices are respectively simple average, composite-plus-scale method, and covariance-based climate field reconstruction. All three reconstruction methods are modified catering to the unique characteristics of precipitation, especially in terms of its large spatial variance. Local reconstructions are carried out first before a national index in reconstructed. Though based on the same documentary and natural proxies, three reconstruction approaches adopt different rationales to decipher the precipitation variability, represented by different statistical models. Each model is assessed by conventional statistics and cross-compared. These models are found complementary to each other while the common shared among three models are considered the closest to the true precipitation condition. Though geographically biased to Eastern China, historical documents still capture the most inter-annual to multi-centennial variations in palaeoprecipitation, indicating the possible control of Asian Monsoon climate on China’s overall precipitation. Tree-ring widths preform worst due in part to the attribute of strong locality. Each reconstruction approach turns out to have its own strength and weakness. Three major falls at multi-centennial timescale are detected in most reconstructed precipitation series, which are at AD600-800, AD1000-1300 and AD1500-1700. Spectral analyses demonstrate a rhythmic pattern of around 400-500 years for all reconstructions. When the proxies are not extrapolated, an additional cycle of 700-800 years is significant in precipitation variability over the past 2,000 years. A cross-comparison with European reconstructions show a high agreement in precipitation variability for the past two millennia, leading to the suspect of dry Medieval Warm Period and wet Little Ice Age over the whole Eurasia. / published_or_final_version / Geography / Master / Master of Philosophy

The study of ceramic variability in Chinese archaeology is conventionally understood in the context of temporal and regional differences, where emphasis is placed on explaining variability in terms of identifying regional styles and long-term changes. In this thesis, I examine ceramic variability of Shang pottery between two contiguous daily-use contexts at Huanbei, a Middle Shang period (1400-1250 BCE) site located in the Central Plains of China. Based on the analysis of pottery sherds collected from daily-use contexts at Hanwangdu (HWD) and Huyuanzhuang (HYZ), I argue that ceramics collected within a single-site context can be highly varied and distinct due to differences in use-context. Assemblage differences and ceramic variation are evaluated according to rim sherd attributes including vessel shape, rim and lip shape, dimensional properties, and surface treatment styles. Possible interpretive models for explaining observed patterns of variability are presented. Results of this study suggest that siginificant variability in pottery vessel design can be observed in the samples examined from the Huanbei site. Consumers from the HWD (a palace context) consumed a greater variety of pottery vessel types but with a more limited range of shapes and decorative styles. In contrast, consumers from HYZ (a non-palatial context) consumed a limited range of pottery vessel types but with a greater variability in the range of shapes and decoration. The observed patterns of variation reinforce current assumptions regarding the contextual differences between HWD and HYZ, and also provide new insight into the differential pottery consumption patterns by different social classes at Huanbei. Results of this study indicate the potential value of studying intra-site ceramic variation in Chinese archaeology and its importance in creating new knowledge on the material consumption behavior of different social classes.

As open pit mines get larger and their road networks more complex, haul road traffic is an area of increasing concern for mine operators. In particular, engineers from Barrick Gold Inc. have observed haul truck interactions in some of their larger open pit mines that are clearly disruptive to the haulage cycle. Such traffic effects cause uncertainty in haul times over identical routes and commercial dispatch systems do not explicitly account for this variability. This research, based on first-hand data collected from the Goldstrike Open Pit in Northern Nevada, focuses on assessing the level of variability in haul times, identifying the sources of said variability, and determining the effects on haulage optimization. Initial data analysis shows different levels of variability over the range of observed haul times, and further investigation identifies certain haulage parameters as significant sources of said variability, such as road topography and intersection effects. Focusing on these areas of interest, relevant data sets were manipulated to reduce levels of data dispersion and compared to observed results in order to quantify the effects in terms of changes to overall mean haul times along identical routes. It was observed that variability has a negative impact on travel times and moderate variability reduction was observed to increase productivity by 1–2 % when used as an input to a simple dispatch simulation program based on the Goldstrike Open Pit. / Thesis (Master, Mining Engineering) -- Queen's University, 2012-08-28 16:02:38.369

No description available.

Climate exerts a fundamental control on ecosystem function, species diversity and distribution. Topographic variability may influence surface climate, through processes operating at a landscape- scale. To quantify and model such influences, the topography of a 72 km(^2) area of complex terrain, (including the Moor House National Nature Reserve in northern England) was analysed at 50 m resolution. A suite of topographic variables was created, including distance relative to the Pennine ridge (dist), and elevation difference between each grid cell and the lowest grid cell within a specified neighbourhood {drain). Automatic weather stations (AWS) were deployed in a series of networks to test hypothetical relationships between landscape and climate. Daily maximum air temperature, daily mean soil temperature and daily potential evapotranspiration can be modelled spatially using a daily lapse rate calculated from the difference between daily observations made at two base stations. On days with a south easterly wind direction, daily mean temperature is estimated as a function of lapse rate and dist; the spatial behaviour of temperature is consistent with a föhn mechanism. Daily minimum temperature is modelled using lapse rate and drain on days with a lapse rate of minimum temperature shallower than -2.03 x 10 C m(^-1), incorporating the effects of katabatic air flow. Daily solar radiation surfaces are estimated by a GIS routine that models interactions between slope and solar geometry and accounts for daily variations in cloudiness and daylight duration. The daily climate surfaces were tested using data measured at a range of AWS locations during different times of year. The accuracy of the daily surfaces is not seasonally-dependent. The spatial climate data are particularly well suited to landscape-scale ecology because the methods account for prevailing topoclimatic constraints and because separate climate surfaces are generated for each day, capturing the high frequency variability characteristic of upland regions.

Knowledge of past chmate variability is vital if the causes of observed chmate changes since instrumental records began are to be fully understood, particularly those, post-1850 AD, possibly due to anthropogenic activity. The past two millennia provide a long enough background with which to compare post-r850 AD change, whilst errors on proxy records remain relatively small. In the Eastem Mediterranean changes in water balance are of particular interest as water is an important resource. Oxygen isotope records from lakes in the region record changes in water balance and are therefore an important archive for observing natural, and anthropogenicaly forced, variabiUty in hydrology. Full understanding of cUmate proxies requires high-resolution analysis through the instramental time period for comparison with measured climate variability. Varved lake sediments provide the possibility for obtaining annually-resolvedarchives of climate proxies, andstrong chronological control through time. In this study gebchemical-climate proxies including oxygen and stable carbon isotope ratios were measured from two lakes in central Turkey with varved sediment archives. Lake Burdur's complex carbonate mineralogy and large catchment led to stable isotope data that is controlled by a variety of mischariisms and highlights the complex nature of some lake-isotope systems. A 1725 year long record was obtained from Nar GolU, with the top 900 years analysed at an annual resolution. Calibration of the top of this record with instmmental cHmate records suggests stable isotope variability at Nar is controlled by changes in evaporation, driven by changes in sunmier temperature and relative humidity. The proxy record from Nar shows sununer evaporation at Nar to be enhanced at times of increased Indian and African monsoon rainfall, and reduced during drier monsoon periods. Major shifts in the chmate system occur c. 500 and c. 1400 AD associated with times of change between relatively warm and cold periods of Northern Hemisphere temperatures. Cycles, with a frequency of 64 years, observed in the Nar isotope record and proxy records of solar activity suggest a solar forcing mechanism for decadal variability in the Eastem Mediterranean-Indian- African sununer climate system.

In other regions of the world, intraseasonal variations of precipitation have been used to extend the range of weather and hydrological forecasts especially during the rainy monsoon season. This intraseasonal variability is usually strongly tied to the Madden Julian Oscillation (MJO). First, the focus is on variations of the MJO as it propagates eastward. Three main categories are described. One is the canonical MJO, which propagates almost continuously from the Indian Ocean to the West Pacific. The other categories encompass intraseasonal convection that fails to reach the West Pacific and intraseasonal convection that begins closer to the Maritime Continent and intensifies while propagating eastward. The categories of intraseasonal convection are linked to intraseasonal variations of South American rainfall and it is demonstrated that the SACZ is influenced by the MJO both through the tropics and extratropics. There is evidence that accumulation of wave energy is an important process both to organize extratropical waves propagating from the Pacific to South America and to promote convection in the South Atlantic Convergence Zone (SACZ). In the long-term, variations of the SACZ are related to climate regimes in the Pacific Ocean, highlighting the fact that there is a shift of spectral energy in SACZ convection from intraseasonal to higher frequencies, indicating again the importance of extratropical waves for SACZ convection. Last, the main findings of this project are discussed, as well as their applicability to enhance precipitation predictability over South America.