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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.
31

Comparative study of wood anatomical properties of Malaysian Sapotaceae

Sulaiman, Ani binti January 1996 (has links)
No description available.
32

Sequence evolution among divergent mitochondrial haplotypes within species of Junonia butterflies

McCullagh, Bonnie 12 1900 (has links)
The New World Junonia butterflies include well-studied model organisms yet their phylogeny remains unresolved by traditional cox1 DNA barcodes. Sixteen Junonia mitochondrial genomes were sequenced using next generation MiSeq technology. Junonia lemonias, an Old World species, has mitochondrial genome features typical of Ditrysian Lepidoptera, and synteny is maintained throughout Junonia. Analysis of Junonia mitogenomes produced a robust phylogeny that was used with biogeographic information to infer that Junonia crossed the Pacific Ocean to invade the New World on 3 separate occasions. Junonia vestina, a high elevation species from the Andes Mountains, shows high altitude adaptation in the mitochondrial protein coding loci atp6, atp8, cox1, cob, nad1, and nad2, with the strongest effects seen in cox1 and nad1. There is some overlap between these genes with human loci that have disease associations with the same amino acid positions which could help elucidate the function of high elevation mutations in J. vestina. / February 2016
33

Thermoregulatory behavior and habitat use of Liolaemus aparicioi at two different altitudes

Gustafsson, Jannie Frida Linn January 2015 (has links)
The thermoregulation of lizards depends highly on the environment they inhabit. Thermoregulation is crucial for physiological processes and affects therefore the life history of the lizard. High altitudes are characterized by a colder climate than on lower altitudes, and these environmental factors affects the thermoregulation of lizards. Lizards can however adapt to colder climates by adjusting their physiology and/or behavior. In this study two populations of Liolaemus aparicioi, an endemic lizard inhabiting the valleys close to La Paz, were observed at two different altitudes to investigate any differences in behavior or habitat use that could compensate for the high altitude. The behavioral displays associated to thermoregulation and the use of habitat were recorded in order to assess how they allocated their time and how they used the habitat available. The mean values of most parameters measured indicated that the population on the high altitude do compensate for the high altitude by behavior and habitat use.
34

Investigating new Service System Solutions for High Altitude Balloons : Feasibility Study and Design Challenges

Peterson, Joakim January 2016 (has links)
The high altitude balloon operations at Esrange Space Center have been goingon since 1972, and about 550 launches have been performed. Their present service system for the high altitude balloons is about 18 years old. To be able to meet the requests from their customers, SSC have started the development of a new service system. A service system contains all features and technology required to perform a high altitude balloon mission. This system is separated from the payload. Important design aspects for the new service system have been investigated to be able to leave recommendations to SSC. These are frequency for the radio communication, modulation scheme for the communication link, prevention of corona discharge, and available computer systems to be used as on-board computers. These design aspects have been evaluated according to the requirements for the development project. Theory, articles, available standards and analyzes have been read and evaluated to reach a conclusion about these subjects. It was found that the best frequency bands are the 400MHz-band, downlink, and the 450MHz-band, uplink. The operation in these bands will be unmodified for many years, and the link suffers little loss. The 2.3GHz-band is interesting from an international perspective, and it is suggested that SSC work to get a band dedicated to aeronautical services in this band. The best modulation scheme for the service system is GMSK, as it has very good spectral eficiency. The corona discharge can only be prevented indirect by SSC, as the phenomena occurs within or between components, aspects which SSC can't control. Standardized methods for tests and specications lists was suggested to minimize the risk of a discharge. The best computer system is an in-house designed service system that have been used on sounding rockets. It fits the present requirements the best. It suggested that the Beaglebone Black should be implemented in basic systems, providing processing and storage via simple serial communication, as it is a very cost eficient solution.
35

Thermoregulating behavior and habitat use of Liolaemus aparicioi

Gustafsson, Jennie Frida Linn January 2015 (has links)
The thermoregulation of lizards depends highly on the environment they inhabit. Thermoregulation is crucial for physiological processes and affects therefore the life history of the lizard. High altitudes are characterized by a colder climate than on lower altitudes, and these environmental factors affects the thermoregulation of lizards. Lizards can however adapt to colder climates by adjusting their physiology and/or behavior. In this study two populations of Liolaemus aparicioi, an endemic lizard inhabiting the valleys close to La Paz, were observed at two different altitudes to investigate any differences in behavior or habitat use that could compensate for the high altitude. The behavioral displays associated to thermoregulation and the use of habitat were recorded in order to assess how they allocated their time and how they used the habitat available. The mean values of most parameters measured indicated that the population on the high altitude do compensate for the high altitude by behavior and habitat use.
36

Effect of simulated altitude exposure on sea level performance

Hinckson, Erica Unknown Date (has links)
Exposure to natural altitude using the "live high-train low" method improves athletic endurance performance at sea level by 1-2%. This method can also be employed with hypoxic devices that simulate altitude, but there is limited and conflicting research on their efficacy. Consequently, three studies were undertaken to investigate changes in sea level performance of endurance runners following exposure to altitude simulated with hypoxic tents. The device was chosen because of its potential for incorporation into the athlete's routine. In Study 1, 10 runners received altitude simulated with hypoxic tents (~9 h overnight at 2500-3500 m) and trained at sea level, while 10 runners in the control group performed usual training. Athletes in both groups performed a lactate-threshold test, but only the altitude group performed a run to exhaustion. The effect on 4-mM lactate speed was unclear, owing to poor reliability of this measure. There was a 16% increase in time to exhaustion in the hypoxic conditioning group, equivalent to a 1.9% (90% likely limits, ±1.4%) increase in speed in a time trial. Effects on performance were not apparent four and eight weeks after use of the tents. To improve precision of the effect of the tents and to determine the effects on performance of different durations, a further controlled trial was performed. A reliability study (Study 2) was first conducted to investigate the potential for runs to exhaustion to provide reliable measures of performance. Eight runners performed a test consisting of three runs to exhaustion lasting ~2, ~4 and ~8 min on six occasions over 14 wk. The critical power and log-log models were used to provide factors for converting variability in time to exhaustion into variability in equivalent time-trial time. Variabilities in time to exhaustion expressed as coefficients of variation for predicted 800-3000 m timetrial times were ~1-3%. A crossover study (Study 3) was then conducted in which 11 athletes performed usual (control) training and usual training with altitude exposure by using tents for 25 ± 3 days (mean ± SD) for 8.1 ± 0.6 h.d-1, progressing from a simulated altitude of 2500 m to 3500 m above sea level. Washout period between control and altitude treatments was four weeks. Performance was assessed with treadmill runs to exhaustion as in Study 2. Improvements in mean predicted times (altitude-control) for standard competition distances of 800, 1500 and 3000 m derived from the runs to exhaustion were 1.0% (±1.3%), 1.4% (±1.2%) and 1.9% (±1.5%) respectively. There was some evidence that hypoxic exposure favoured those athletes carrying the I allele for angiotensin converting enzyme. In summary, the main finding from the series of studies is that hypoxic tents are likely to enhance sea level endurance running performance by ~1-2%.
37

Effects of altitude exposure combined with sea level training on sea level performance

Wood, Matthew R Unknown Date (has links)
Athletes commonly use various forms of real and simulated altitude exposure combined with sea level training to enhance sea-level performance. Altitude can be simulated through use of apartments, tents and masks that allow athletes to breathe air containing less oxygen. There is clear evidence that altitude exposure combined with sea-level training enhances endurance performance especially when the altitude is real. It is unclear what the optimum level of altitude and length of exposure is to enhance performance, although researchers generally adopt 3-4 weeks at moderate altitude (~3000m). There is also little evidence to suggest how long the performance effect persists for. Large gains in VO2max have been reported following actual altitude exposure that may be partly mediated via an increase in red cell volume or haemoglobin mass. However, exposure to simulated altitude appears to have a little effect on VO2max probably due to differences in daily exposure time. The effects of altitude exposure on sprint performance are limited to several investigations that demonstrate a tendency for improved performance, especially in repeated sprints.
38

The acute physiological responses of elite cross country skiers to exercise at sea level and moderate altitude

Daley, Phillipa J., n/a January 1999 (has links)
Nine Australian male cross country ski team members (19.8±2.5 years, (X±SD),76.6±6.4kg, 184.8±4.9cm) completed both an incremental maximal exercise test and a 45 minute time trial performance test using a dryland ski striding technique with poles on a treadmill. Testing occurred at 610m in a chamber that was supplied with either an 02 enriched (p02 = 152mmHg) or an N2 enriched (p02 = 132mmHg) gas mixture to simulate sea level (SL) or 1800m (A) conditions respectively. A 48 hour rest interval was provided between tests and the testing conditions were randomised, counterbalanced and double blind. At maximum effort there were significant differences in V02 max (70.2±4.0 v 61.7±2.9 ml.kg-1.min-1), PaO2 (97.2±12.7 v 77.1±11.2 mmHg) and SaO2 (90.6±4.9 v 77.8±3.9%); but not in HR (194.1±8.1 v 191.7±7.4 bpm), VE (133.1±12.8 v 132.6±11.3 L.min-1 STPD) or [La] (14.2±2.3 v 13.7±3.3 mM) at SL v A. There was a decrease of 7.6% in overall time trial performance between the conditions (4005±378 v 3702±301 m, p = 0.08), although performance was significantly lower at A during the latter period of the test, >25 minutes. During the steady state stage of the time trial performance test, (=75% SL VO2 max) there were no significant differences between SL and A in any of VO2 (52.9±5.9 v 52.1±4.9 ml.kg-'.min-' at 15 minutes for SL and A respectively); HR (173.1±12.8 v 176.1+10.1 bpm); or [La] (3.0±1.0 v 4.8±2.2 mM). However, there was a significant reduction in PaO2 between SL (111.2±25.5 mmHg at 15 minutes) and A (72.6±24.3 mmHg at 15 minutes), resulting in a significant reduction in SaO2 (96.6±1.1 v 84.6±6.8% at 15 minutes) between the conditions. At the end of each lap of the variable workload stage of the time trial performance test there were significant reductions in VO2 (65.3±6.9, 64.2±6.3 and 66.4±5.9 v 54.6±5.6, 56.0±4.6 and 57.9±3.2 ml.kg-'.min-1 at 25, 35 and 45 minutes at SL v A); and HR (190.1 ±9.2, 192.4±8.6 and 195.9±7.6 v 181.8±12.4, 186±8.1 and 189.6±9.2 bpm) under A conditions. There were no significant differences in [La] at the end of each lap of the time trial performance test between SL and A, although [La] did increase over time during the test at both SL and A (6.2±2.0, 8.9±2.8 and 10.6±4.1 v 7.6±2.0, 8.4±2.2 and 9.9± 1.8 mM). At the end of each lap of the time trial performance test, there was a significant reduction in PaO2 (120.9±24.4, 108.8±25.9 and 103.0±23.0 v 86.0±31.4, 94.9±22.3 and 71.1±3.2 mmHg); and SaO2 (94.6±2.4, 94.3±2.4 and 92.3±3.4 v 85.9±5.8, 84.3±6.4 and 81.7±6.1%) and both PaO, and SaO2 decreased over time during the test at both SL and A. This study has indicated that as well as the extent of hypoxia induced by altitude, both exercise intensity and duration may impact on the magnitude of the response to sustained exercise at altitude, such as in cross country ski racing.
39

Tillämpningar av ledarskap från höghöjdsexpeditioner : Användningsområde - krissituationer

Karlsson, Patrik January 2012 (has links)
The institution of Engineering Sciences at Uppsala University in cooperation with Umeå University is working on a project where they will examine the decision-making in extreme situations. A part of this project is to investigate leadership in high altitudes expeditions. This report will discusses the type of leadership used in high altitudes expeditions. Then, to examine how well you can use it in companies and organizations, and the ability to prevent company’s disasters with this kind of leadership. This is done by studying different company’s stories, where they gone bankrupt or fallen into a deep crisis. This is done to find out if high altitude leadership, which is the type of leadership used in high altitudes expeditions, can prevent the end of companies or organizations got. The report contains the conclusions I have drawn from HAL (high altitude leadership) in the different stories. They include the parts of HAL that is interesting and the conclusion that it may be better to use it as a leadership tool than a type of leadership.
40

Development of an Underwater Vehicle Simulation Platform

Du, Jiun-Hua 15 November 2011 (has links)
In the development of underwater vehicles, it is necessary to conduct performance test in the water tank. However, different factors need to be considered depending on different cases. The purpose of this paper is to construct a simulation platform in the air to study the scenarios like side current or constant height profiling. Although these tests are difficult to be performed in the water tank, we can get some solutions from observing the dynamics of simulation platform. The simulation platform we used consists of three links to constraint the motion in a polar coordinate system. It carries a wireless micro-camera, and two DC motor-driven propellers. At the end of the distal link and metal disk is attached on the other side of the pivot of the last link to provide counter-weight which can simulate different status of the "buoyancy" of the platform. The encoder which is uses to trace the motion of the simulation platform, is mounted at each join between two links. The control program has two parts: servo control of propellers and target tracking. In order to approach to the real-time searching, we derived image with gray scale instead of color form to increase image refreshing rate during the tracking process. For the current experiment, the target is at dot generated by an LED. The location of the bright dot is detected by a histogram-based threshold, and the actual location is further refined with intensity-weighted algorithm. The offset between of the target and the center of the image is used as the feedback to command the propellers to drive the platform. The goal is to keep the target at the center of the image as close as possible. A linear PD control (proportional - derivative) is implemented to drive the propellers. Preliminary experiments show that the simulation platform can track a target with about 15 frames per second refreshing rate under the condition that the target does not move too fast and vanishes in the image. When ROV with laser scanner syetem, seafloor away from ROV's accuracy is necessary. In this eassay, we use tracking angle and tracking bright dot to qualify and quantify the influence of buoyancy and propeller on the altitude control in different cases.

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