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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.
61

Comunidade dormente e ativa de Cladocera em habitats da zona litorânea de lagoas marginais

Daré, Luana. January 2019 (has links)
Orientador: Jorge Laço Portinho / Resumo: O objetivo deste estudo foi conhecer a distribuição de Cladocera na zona litorânea de lagoas marginais, abrangendo a comunidade de forma completa, incluindo suas formas ativa e dormente, encontradas nos habitats que compõem essa região: coluna d’água, sedimento e banco de macrófitas. O estudo foi realizado em quatro lagoas marginais. Em cada lagoa foram definidas quatro estações de amostragem, em cada estação foram amostrados os três habitats, sedimento e macrófita (comunidade dormente), e coluna d’água abaixo das macrófitas (comunidade ativa). Ao investigar essa organização, observamos que a comunidade de Cladocera se distribui de forma heterogênea entre os três habitats. O banco de ovos no sedimento apresenta maior riqueza de espécies e maior número de ovos, quando comparado ao banco de ovos nas macrófitas. A comunidade ativa e os bancos de ovos apresentam elevada interação em relação à deposição e eclosão de ovos. O sedimento e a coluna d’água são os principais habitats onde as espécies se distribuem, e embora apresentem elevada similaridade entre si (táxons em comum), esses habitats isoladamente não são capazes de representar de forma completa a composição e riqueza da comunidade de Cladocera da região litorânea, pois cada um apresenta táxons de ocorrência exclusiva. / Abstract: The objective of this study was to know the distribution of Cladocera in littoral area of marginal lagoons, covering the community completely, including its active and dormant forms found in the habitats that make up this area: macrophytes bank, sediment and water column. The study was carried out in four marginal lakes. In each lake four sampling stations were defined, in each station the three habitats were sampled, sediment and macrophyte (dormant egg banks), and water column below the macrophytes (active community). In investigating this organization, we observed that the community of Cladocera is distributed heterogeneously among the three habitats. The egg bank in the sediment presents higher species richness and higher egg numbers when compared to egg banks in macrophytes. The active community and the egg banks present high interaction in relation to resting eggs deposition and hatching. The sediment and the water column are the main habitats where the species are distributed, and although they have a high similarity between them (common taxa), these habitats alone are not able to fully represent the composition and richness of the community of Cladocera in littoral area, since each one presents taxa of exclusive occurrence. / Mestre
62

Comparing Steady State to Time Interval Measurements of Resting Metabolic Rate

Irving, Chelsea Jayne 01 April 2016 (has links)
The two most common methods to measure resting metabolic rate using indirect calorimetry are steady state or time interval. Steady state is commonly defined as the first five minutes in which oxygen consumption and carbon dioxide production vary by <10%. A time interval measurement generally lasts 20-60 minutes. Using steady state criteria is often harder to achieve, but many suggest it more accurately measures resting metabolic rate. Our objective was to determine if there were differences between steady state and time interval measurements in a healthy adult population. Seventy seven subjects were measured for 45 minutes. Inclusion criteria included healthy subjects ages 18-65, excluding pregnant and lactating women. Paired t-tests analyzed differences between measures, and Bland-Altman plots evaluated bias, precision, and accuracy. Of 77 subjects, 84% achieved steady state, and 95% achieved SS by minute 30. Most differences between steady state and time intervals were statistically but not practically significant. Bland-Altman plots showed steady state measurements were generally lower indicating that steady state is more indicative of resting metabolic rate. Minutes 6-25 were most precise, accurate and fairly unbiased compared to steady state. We recommend measuring a subject for 30 minutes and using steady state criteria of <10% variation of oxygen consumption and carbon dioxide production for five minutes if a subject is able to achieve it. However, if a subject cannot achieve steady state, we recommend averaging minutes 6-25.
63

Language and reading dysfunction in boys with isolated cleft lip and/or palate : a relationship to abnormal structural and functional connectivity in the brain

DeVolder, Ian John 01 December 2015 (has links)
Orofacial clefts are among the most common congenital defects in the United States, affecting roughly 1 in 600 births annually. A majority of these cases are considered to be “isolated” clefts of the lip and/or palate (ICLP). However the term “isolated” is somewhat of a misnomer, as functional deficits frequently accompany ICLP. One of the most problematic yet understudied of these deficits involves the high prevalence of reading disabilities in this population. It has been estimated that as high as 46% of children with ICLP will be diagnosed with a reading disability, particularly dyslexia. Despite this high prevalence and the well-established neurological basis of dyslexia, relatively little attention has been paid to the role that brain development plays in the reading problems in ICLP. Previous studies from our lab have demonstrated significant changes in brain structure in children with ICLP (that have importantly correlated with functional measures). However we have yet to combine both a structural and functional neuroimaging study with an in-depth analysis of reading dysfunction in this population. The current study examined boys with ICLP, age 8-12 (boys have a higher prevalence of ICLP and show more significant reading problems that girls with ICLP) compared to healthy control boys. Measures of cognitive functioning were obtained with an emphasis on reading and language skills. In addition MRI scans were obtained which included volumetric measures, diffusion-weighted measures (DWI; white matter), and connectivity measures (resting-state fMRI). Even after controlling for the effect of socioeconomic status, boys with ICLP showed significant decreases in reading and language skills (particularly reading fluency). Boys with ICLP did not show significant differences on phonlogical measures (the primary cause of dyslexia). In addition, phonological measures were not predictive of reading fluency, while object naming tasks were predictive of reading fluency in boys with ICLP. For white matter integrity, measures of fractional anisotropy (FA) were found to be increased in the right occipital lobe for boys with ICLP indicating more organized white matter in this region. This increase in right occipital FA was also predictive of better reading outcomes, particularly reading fluency. For more specific white matter tracts, only the fornix and the tapetum (both associated with the temporal lobes) showed a significant difference with a decrease in FA for boys with ICLP. The decrease in FA in the tapetum was also predictive of better reading outcomes in ICLP. When looking at resting-state networks, boys with ICLP showed an increase in connectivity within posterior and subcortical regions when compared to healthy control boys, indicating stronger network connections within the posterior language regions of the brain. Taken together, these results point to differences in both structural and functional connectivity in the brains boys with ICLP. Furthermore, this pattern is different than that found in children with developmental dyslexia as there appears to be no disruption of the posterior reading systems. Cognitive measures also indicate normal phonological awareness in this group, further distinguishing them from dyslexic children. Boys with ICLP instead may be over-relying on these posterior, more visually oriented reading systems as a compensatory mechanism to overcome problems with the development of the typical “lexical route” of reading.
64

The Effect of the Estimate of Resting Metabolic Rate on the Correlation Between Energy Expenditure as Estimated Using Self-Reports of Physical Activity and Food Intake Records in Older Adults

Hurd, Judy 01 May 1998 (has links)
This study measured total daily energy expenditure (TDEE) in adults at least 50 years of age. The goal was to determine the effect of the estimate of resting metabolic rate (RMR) on the relationship between energy expenditure estimates made using (a) self-reports of physical activity and (b) food intake records. The objectives were to determine if (a) RMR estimates based on body composition, body weight, and the 111 metabolic cart were strongly related to each other, and (b) TDEE estimates based on a 7- day physical activity diary and a 7-day food intake record were more strongly related to each other when an RMR was used that was based on body composition, body weight, or the met cart. This was a three-phase study. In phases I and II, the Pearson r was computed for all combinations of methods . If r > .80, the most practical method for field use was used in the next phase. Phase I: Estimated body composition using bioimpedance (BIA), skinfold (SKF), and girth. Phase II: Measured RMR using a met cart and three equations. Phase III: Computed TDEE using the self-reports. The Pearson r was computed to determine which methods of estimating RMR resulted in the strongest relationships. Forty-four older adults participated. Phase I: r = .88 for SKF, girth; r = .64 for SKF, BIA. Phase II: rs ranged from .47 to .59 between the met cart-RMR and all the other methods; rs ranged from .84 to .98 for the remaining methods. Phase III: r = .41 between the two estimates of TDEE that used a body weight -RMR; r = .59 between estimates using a met cart-RMR; and r = .58 between estimates using a body composition-RMR. Even though r = .59 and r = .58 are similar, the average individual difference between the two estimates for each participant was smaller for the metabolic cart- RMR (372 calories /day) than for the body composition-RMR (1,045 calories /day), which suggests that body composition is not as useful as a met cart when estimating TDEE for older adults . When estimating clients' daily calorie needs, health professionals ought to consider using a met cart to estimate RMR and TDEE instead of other methods .
65

Aerobic Degradation of Tetracyanonickelate¡]II¡^by Azotobacter vinelandii

Li, Shu-Hui 01 July 2003 (has links)
In this study, Azotobacter vinelandii ATCC13705 (A. vinelandii), which is a free-living, nitrogen-fixing, gram-negative, and aerobic rod bacterium, was need to evaluate its ability to biodegrade tetracyanonickelate (TCN) under different conditions. Results show that A. vinelandii was able to biodegrade various concentrations of TCN (1, 10, and 20 mM) under aerobic conditions. Oxygen consumption and nitrogenase activity were investigated at 1 mM of TCN. Results indicate that the production of ammonia and methane was observed when TCN was consumed. Results suggest that nitrogenase was possibly involved in the enzymatic degradation of TCN. Moreover, higher degradation rate of TCN, higher nitrogenase activity, higher oxygen consumption, and higher specific growth rates were also observed at log growth period. Results suggest that the hypothesis of respiratory protection of nitrogenase is supported. Moreover, the addition of ammonia (1, 5, and 10 mM) would cause the decrease of TCN degradation rate (28%) during a 24-hr incubation period. Inhibition of TCN degradation (degradation rate¡G16% for 24 hrs) was observed when nitrite (5 and 10 mM) was added into the growth medium. Furthermore, the addition of 8% of glucose would significantly enhance the TCN degradation by the resting cells (degradation rate¡G43% for 8 hrs) . Results from this study provide us insight into the characteristics and mechanisms of TCN conversion by A. vinelandii.
66

Parcellation of the human sensorimotor cortex: a resting-state fMRI study

Long, Xiangyu 12 June 2015 (has links) (PDF)
The sensorimotor cortex is a brain region comprising the primary motor cortex (MI) and the primary somatosensory (SI) cortex. In humans, investigation into these regions suggests that MI and SI are involved in the modulation and control of motor and somatosensory processing, and are somatotopically organized according to a body plan (Penfield & Boldrey, 1937). Additional investigations into somatotopic mapping in relation to the limbs in the peripheral nervous system and SI in central nervous system have further born out the importance of this body-based organization (Wall & Dubner, 1972). Understanding the nature of the sensorimotor cortex‟s structure and function has broad implications not only for human development, but also motor learning (Taubert et al., 2011) and clinical applications in structural plasticity in Parkinson‟s disease (Sehm et al., 2014), among others. The aim of the present thesis is to identify functionally meaningful subregions within the sensorimotor cortex via parcellation analysis. Previously, cerebral subregions were identified in postmortem brains by invasive procedures based on histological features (Brodmann, 1909; Vogt. & Vogt., 1919; Economo, 1926; Sanides, 1970). One widely used atlas is based on Brodmann areas (BA). Brodmann divided human brains into several areas based on the visually inspected cytoarchitecture of the cortex as seen under a microscope (Brodmann, 1909). In this atlas, BA 4, BA 3, BA 1 and BA 2 together constitute the sensorimotor cortex (Vogt. & Vogt., 1919; Geyer et al., 1999; Geyer et al., 2000). However, BAs are incapable of delineating the somatotopic detail reflected in other research (Blankenburg et al., 2003). And, although invasive approaches have proven reliable in the discovery of functional parcellation in the past, such approaches are marked by their irreversibility which, according to ethical standards, makes them unsuitable for scientific inquiry. Therefore, it is necessary to develop non-invasive approaches to parcellate functional brain regions. In the present study, a non-invasive and task-free approach to parcellate the sensorimotor cortex with resting-state fMRI was developed. This approach used functional connectivity patterns of brain areas in order to delineate functional subregions as connectivity-based parcellations (Wig et al., 2014). We selected two adjacent BAs (BA 3 and BA 4) from a standard template to cover the area along the central sulcus (Eickhoff et al., 2005). Then subregions within this area were generated using resting-state fMRI data. These subregions were organized somatotopically from medial-dorsal to ventral-lateral (corresponding roughly to the face, hand and foot regions, respectively) by comparing them with the activity maps obtained by using independent motor tasks. Interestingly, resting-state parcellation map demonstrated higher correspondence to the task-based divisions after individuals had performed motor tasks. We also observed higher functional correlations between the hand area and the foot and tongue area, respectively, than between the foot and tongue regions. The functional relevance of those subregions indicates the feasibility of a wide range of potential applications to brain mapping (Nebel et al., 2014). In sum, the present thesis provides an investigation of functional network, functional structure, and properties of the sensorimotor cortex by state-of-art neuroimaging technology. The methodology and the results of the thesis hope to carry on the future research of the sensorimotor system.
67

Automatic Sleep Scoring To Study Brain Resting State Networks During Sleep In Narcoleptic And Healthy Subjects : A Combination Of A Wavelet Filter Bank And An Artificial Neural Network

Viola, Federica January 2014 (has links)
Manual sleep scoring, executed by visual inspection of the EEG, is a very time consuming activity, with an inherent subjective decisional component. Automatic sleep scoring could ease the job of the technicians, because faster and more accurate. Frequency information characterizing the main brain rhythms, and consequently the sleep stages, needs to be extracted from the EEG data. The approach used in this study involves a wavelet filter bank for the EEG frequency features extraction. The wavelet packet analysis tool in MATLAB has been employed and the frequency information subsequently used for the automatic sleep scoring by means of an artificial neural network. Finally, the automatic sleep scoring has been employed for epoching the fMRI data, thus allowing for studying brain resting state networks during sleep. Three resting state networks have been inspected; the Default Mode Network, The Attentional Network and the Salience Network. The networks functional connectivity variations have been inspected in both healthy and narcoleptic subjects. Narcolepsy is a neurobiological disorder characterized by an excessive daytime sleepiness, whose aetiology may be linked to a loss of neurons in the hypothalamic region.
68

Grizzly bear response to open-pit mining in western Alberta, Canada

Cristescu, Bogdan Unknown Date
No description available.
69

Gestational Weight Gain and Body Composition Changes during Pregnancy and Early Postpartum

Subhan, Fatheema Begum Unknown Date
No description available.
70

Parasite mediated selection, sex and diapause in a natural population of Daphnia

Duncan, Alison B. January 2006 (has links)
Parasites are thought to have large effects on their host populations, driving genetic change, population density changes, speciation and be a major selective force maintaining sexual reproduction. Indirect signatures of parasite-mediated selection are common, but explicit examples of parasite-mediated selection in nature are lacking. In this thesis I examine parasite-mediated dynamics in a natural population of Daphnia magna that experiences an annual epidemic of the bacterial pathogen Pasteuria ramosa. I also test a novel hypothesis investigating the relationship between parasitism and the production of resting eggs. In chapter 2 a combined field study and laboratory infection experiment illustrates one of the best examples of parasite-mediated selection in a natural population, with Daphnia collected after a parasite epidemic having higher levels of parasite resistance than those collected before. This chapter also explored the relationship between parasitism and resting eggs, which are only produced during the sexual phase of reproduction. Daphnia that were reproducing sexually in the field prior to the parasite epidemic were more susceptible, supporting higher levels of parasite growth, than their asexual counterparts. This supports the idea that some genotypes invest in sex at the expense of parasite resistance. In chapter 3 I used molecular markers to investigate genotype frequency changes in the same population in relation to the parasite epidemic. The parasite epidemic was found to be associated with genetic change in the population, and a laboratory infection experiment revealed that the genotype most resistant to the parasite was also most common following the peak of the parasite epidemic. While chapter 2 explored a genetic relationship between susceptibility and resting eggs, chapter 4 explores whether crowding conditions, cues indicating parasite prevalence in the population, or direct exposure to parasite spores can induce resting egg production. I found that crowding conditions or parasite prevalence enhance levels of male and resting egg production, but patterns were entirely dependent on Daphnia genotypes. There was no indication that exposure to parasite spores affects levels of sexual reproduction.

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