Bone speed of sound in overweight and normal-weight girls and adolescents

Over the last two decades, the prevalence of obesity in the general population has been steadily increasing. Obesity is a major issue in scientific research because it is associated with many health problems, one of which is bone quality. In adult females, adiposity is associated with increased bone mineral density, suggesting that there is a protective effect of fat on bone. However, the association between adiposity and bone strength during childhood is not clear. Thus, the purpose of this study was to compare bone strength, as reflected by speed of sound (SOS), of overweight and obese girls and adolescents with normal-weight age-matched controls. Data from 75 females included normal-weight girls (G-NW; body fat:::; 25%; n = 21), overweight and obese girls (GOW; body fat ~ 28%; n = 19), normal-weight adolescents (A-NW, body fat:::; 25%; n = 13) and overweight and obese adolescents (A-OW; body fat ~ 28%; n = 22). Nutrition was assessed with a 24-hour recall questionnaire and habitual physical activity was measured for one week using accelerometry. Using quantitative ultrasound (QUS; Sunlight Omnisense™), bone SOS was measured at the distal radius and mid-tibia. No differences were found between groups in daily total energy, calcium or vitamin D intake. However, all groups were below the recommended daily calcium intake of 1300 mg (Osteoporosis Canada, 2008). Adolescents were significantly less active than girls (14.7 ± 0.6 vs. 6.3 ± 0.6% active for G and A, respectively). OW accumulated significantly less minutes of moderate-to-very vigorous physical activity per day (MVPA) than NW in both age groups (114 ± 6 vs. 57 ± 5 min/day for NW and OW, i respectively). Girls had significantly lower radial SOS (3794 ± 87 vs. 3964 ± 64 mls for G-NW and A-NW, respectively), and tibial SOS (3678 ± 86 vs. 3878 ± 52 mls for G-NW and A-NW, respectively) than adolescents. Radial SOS was similar in the two adiposity groups within each age group. However, tibial SOS was lower in the two overweight groups (3601 ± 75 mls vs. 3739 ± 134 mls for G-OW and A-OW, respectively) compared with the age-matched normal-weight controls. Body fat percentage negatively correlated with tibial SOS in the study sample as a whole (r = -0.30). However, when split into groups, percent bo~y fat correlated with tibial SOS only in the A-OW group (r = -0.53). MVPA correlated with tibial SOS (r = 0.40), once age was partialed out. In conclusion, in contrast withthe higher bone strength characteristic of obese adult women, overweight and obese girls and adolescents are characterized by low tibial bone strength, as assessed with QUS. The differences between adiposity groups in tibial SOS may be at least partially due to the reduced weight-bearing physical activity levels in the overweight girls and adolescents. However, other factors, such as hormonal influences associated with high body fat may also playa role in reducing bone strength in overweight girls. Further research is required to reveal the mechanisms causing low bone strength in overweight and obese children and adolescents.

Towards a better understanding of the relationship between speed of internationalization and performance outcomes among young international ventures

This thesis offers an explanation for the inconsistent relationship between speed of internationalization and performance outcomes in the context of young international ventures. We argue that the variables of scope of internationalization, entrepreneurial orientation and degree of internationalization play a moderating role in the relationship between speed of internationalization and performance outcomes of international new ventures (INVs). Using primary survey data from INVs in China, we found empirical support for significant moderating impact of scope of internationalization, entrepreneurial orientation variables and no support for the moderating impact of degree of internationalization variable. The results suggest that business managers of INVs shall consider the applied moderating variables as an effective tool kit to enhance firm performance in foreign markets and to mitigate any potential risks of early internationalization.

Effect of harvest date on the dormancy period of yam (Dioscorea rotundata)

Tuber dormancy enables yams to survive in the ground during the dry season and post-harvest storage. Three clones of Dioscorea rotundata were harvested after five intervals and then stored in a cooler (20.6°C) or at ambient temperature (27.8°C). The time from harvest to sprouting was shorter as harvest was delayed. The period from sowing to sprouting for each clone was similar for tubers harvested from 140 days after planting, but tubers harvested earlier took longer to sprout. The cooler temperature delayed sprouting. Tubers of two clones sprouted after only 70 days of crop growth. If the dormancy period of these young tubers can be broken, the generation time of yam crop improvement programmes could be considerably reduced.

On the speed of the eddy-driven jet and the width of the Hadley cell in the Southern Hemisphere

A strong correlation between the speed of the eddy-driven jet and the width of the Hadley cell is found to exist in the Southern Hemisphere, both in reanalysis data and in twenty-first-century integrations from the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report multimodel archive. Analysis of the space–time spectra of eddy momentum flux reveals that variations in eddy-driven jet speed are related to changes in the mean phase speed of midlatitude eddies. An increase in eddy phase speeds induces a poleward shift of the critical latitudes and a poleward expansion of the region of subtropical wave breaking. The associated changes in eddy momentum flux convergence are balanced by anomalous meridional winds consistent with a wider Hadley cell. At the same time, faster eddies are also associated with a strengthened poleward eddy momentum flux, sustaining a stronger westerly jet in midlatitudes. The proposed mechanism is consistent with the seasonal dependence of the interannual variability of the Hadley cell width and appears to explain at least part of the projected twenty-first-century trends.

A dislocation based theory for the deformation hardening behavior of DP steels : Impact of martensite content and ferrite grain size

A dislocation model, accurately describing the uniaxial plastic stress-strain behavior of dual phase (DP) steels, is proposed and the impact of martensite content and ferrite grain size in four commercially produced DP steels is analyzed. It is assumed that the plastic deformation process is localized to the ferrite. This is taken into account by introducing a non-homogeneity parameter, f(e), that specifies the volume fraction of ferrite taking active part in the plastic deformation process. It is found that the larger the martensite content the smaller the initial volume fraction of active ferrite which yields a higher initial deformation hardening rate. This explains the high energy absorbing capacity of DP steels with high volume fractions of martensite. Further, the effect of ferrite grain size strengthening in DP steels is important. The flow stress grain size sensitivity for DP steels is observed to be 7 times larger than that for single phase ferrite.

The Optimal trigger speed of vehicle activated signs

The thesis aims to elaborate on the optimum trigger speed for Vehicle Activated Signs (VAS) and to study the effectiveness of VAS trigger speed on drivers’ behaviour. Vehicle activated signs (VAS) are speed warning signs that are activated by individual vehicle when the driver exceeds a speed threshold. The threshold, which triggers the VAS, is commonly based on a driver speed, and accordingly, is called a trigger speed. At present, the trigger speed activating the VAS is usually set to a constant value and does not consider the fact that an optimal trigger speed might exist. The optimal trigger speed significantly impacts driver behaviour. In order to be able to fulfil the aims of this thesis, systematic vehicle speed data were collected from field experiments that utilized Doppler radar. Further calibration methods for the radar used in the experiment have been developed and evaluated to provide accurate data for the experiment. The calibration method was bidirectional; consisting of data cleaning and data reconstruction. The data cleaning calibration had a superior performance than the calibration based on the reconstructed data. To study the effectiveness of trigger speed on driver behaviour, the collected data were analysed by both descriptive and inferential statistics. Both descriptive and inferential statistics showed that the change in trigger speed had an effect on vehicle mean speed and on vehicle standard deviation of the mean speed. When the trigger speed was set near the speed limit, the standard deviation was high. Therefore, the choice of trigger speed cannot be based solely on the speed limit at the proposed VAS location. The optimal trigger speeds for VAS were not considered in previous studies. As well, the relationship between the trigger value and its consequences under different conditions were not clearly stated. The finding from this thesis is that the optimal trigger speed should be primarily based on lowering the standard deviation rather than lowering the mean speed of vehicles. Furthermore, the optimal trigger speed should be set near the 85th percentile speed, with the goal of lowering the standard deviation.

Speed of adjustment of capital structure: empirical study

We analyze the impact of firm-specific characteristics as well as economic factors on the speed of adjustment to the target debt ratio. Using different methods, we document speeds of adjustment ranging from 14.4% to 37%. The results indicate that the speed of adjustment is affected by business-cycle variables: The interaction term related to term spread reveals, as expected, faster adjustment in booms than in recessions and a negative relationship between short term spread and adjustment speed. We also show that the speed of adjustment becomes stationary when the increasing fractions of zero-debt firms are considered.

Electrical conductivity of the seed soaking solution and soybean seedling emergence

Vigor of soybean [Glycine max (L.) Merrill] seeds can be evaluated by measuring the electrical conductivity (EC) of the seed soaking solution, which has shown a satisfactory relationship with field seedling emergence, but has not had aproper definition of range yet. This work studies the relationship between EC and soybean seedling emergence both in the field and laboratory conditions, using twenty two seed lots. Seed water content, standard germination and vigor (EC, accelerated aging and cold tests) were evaluated under laboratory conditions using -0.03; -0.20; -0.40 and -0.60 MPa matric potentials, and field seedling emergence was also observed. There was direct relationship between EC and field seedling emergence (FE). Under laboratory conditions, a decreasing relationship was found between EC and FE as water content in the substrate decreased, Relationships between these two parameters were also found when -0.03; -0.20 and -0.40 MPa matric potentials were used. EC tests can be used successfully to evaluate soybean seed vigor and identify lots with higher or lower field emergence potential.

Tamanho e secagem de sementes de palmeira Jussara sobre a germinação e o vigor

With the objective to determine the influence of the dehydration and of the size and/or weight on germination percentage and the vigor of jussara palm seeds (Euterpe edulis Mart.), 10 individuals' ripe fruits, picked in the Experimental Station of Ubatuba (IAC) they were classified by size in 5 sieves of circular sieve: 26/64" (10,31mm), 28/64" (11,11mm), 30/64" (11,90mm), 32/64" (12,69mm) and 34/64" (13,49mm). It was determined, the medium weight of the classified seeds. The quality of the seeds was evaluated through the following parameters: water content of the seeds; germination and vigor (first germination counting). It was evaluated the drying speed of different seed sizes for 48 hours, in dry chamber. The sizes of 28/64", 30/64" and 32/64" represented 98,7% of the total weight of the harvested seeds and showed similar drying speed, percentage of germination and vigor. With the increase of the drying period, the smaller seeds (28/64") had their germination less affected them the intermediate (30/64") and bigger sized seeds (32/64").

Improved germination of soybean seed treated with thiamethoxam under drought conditions

The effect of thiamethoxam on germination of soybean (Glycine max L.) seeds cv. Pintado under water deficit was studied. When used as insecticide at the recommended level (100/100 kg seeds) in the treatment of soybean seeds. thiamethoxam accelerated germination. Soybean germination was delayed under lower water availability: however pretreatment of seeds with thiamethoxam reduced the negative effects of water deficit on such process.

Seed size variation in the palm Euterpe edulis and the effects of seed predators on germination and seedling survival

Intraspecific variation in seed size is common in wild plant populations and has important consequences for the reproductive success of individual plants. Multiple, often conflicting evolutionary forces mediated by biotic as well as abiotic agents may maintain such a variation. In this paper we assessed seed size variation in a population of the threatened, commercially important palm Euterpe edulis in southeast Brazil. We investigated (i) how this variation affects the probability of attack by vertebrate and invertebrate post-dispersal seed predators, and (ii) if seed size influences the outcome of seeds damaged by beetles in terms of seed germination and early survival of seedlings. Euterpe edulis seeds varied in diameter from 8.3 to 14.1 mm. Neither insects nor rodents selected the seeds they preyed upon based on seed size. Seed germination and total, shoot and root biomasses of one-year seedlings were significantly and positively affected by seed size. Root biomass and seedling survival were negatively affected by seed damage caused by a scolytid beetle (Coccotrypes palmarum) whose adults bore into seeds to consume part of the endosperm, but do not oviposit on them. Seed size had a marginally significant effect on seedling survival. Therefore, if any advantage is accrued by E. edulis individuals producing large seeds, this is because of greater seed germination success and seedling vigor. If this is so, even a relatively narrow range of variation in seed size as observed in the E. edulis population studied may translate into differential success of individual plants. (c) 2006 Elsevier SAS. All rights reserved.