Effects of Time of Day and Sleep Deprivation on Motorcycle-Driving Performance

The aim of this study was to investigate whether motorcycle handling capabilities – measured by means of the efficiency of emergency manoeuvres – were dependent on prior sleep deprivation and time of day. Twelve male participants voluntarily took part in four test sessions, starting at 6 a.m., 10 a.m., 2 p.m., and 6 p.m., following a night either with or without sleep. Each test session comprised temperature and sleepiness measurements, before three different types of motorcycling tests were initiated: (1) stability in straight ahead riding at low speed (in “slow motion” mode and in “brakes and clutch” mode), (2) emergency braking and (3) crash avoidance tasks performed at 20 kph and 40 kph. The results indicate that motorcycle control at low speed depends on time of day, with an improvement in performance throughout the day. Emergency braking performance is affected at both speeds by time of day, with poorer performance (longer total stopping distance, reaction time and braking distance) in the morning, and also by sleep deprivation, from measurements obtained at 40 kph (incorrect initial speed). Except for a tendency observed after the sleepless night to deviate from the initial speed, it seems that crash avoidance capabilities are quite unaffected by the two disturbance factors. Consequently, some motorcycle handling capabilities (stability at low speed and emergency braking) change in the same way as the diurnal fluctuation observed in body temperature and sleepiness, whereas for others (crash avoidance) the participants were able to maintain their initial performance level despite the high levels of sleepiness recorded after a sleepless night. Motorcycle riders have to be aware that their handling capabilities are limited in the early morning and/or after sleep deprivation. Both these situations can increase the risk of falls and of being involved in a road accident

Sleep-amount differentially affects fear-processing neural circuitry in pediatric anxiety: A preliminary fMRI investigation

Insufficient sleep, as well as the incidence of anxiety disorders, both peak during adolescence. While both conditions present perturbations in fear-processing-related neurocircuitry, it is unknown whether these neurofunctional alterations directly link anxiety and compromised sleep in adolescents. Fourteen anxious adolescents (AAs) and 19 healthy adolescents (HAs) were compared on a measure of sleep amount and neural responses to negatively valenced faces during fMRI. Group differences in neural response to negative faces emerged in the dorsal anterior cingulate cortex (dACC) and the hippocampus. In both regions, correlation of sleep amount with BOLD activation was positive in AAs, but negative in HAs. Follow-up psychophysiological interaction (PPI) analyses indicated positive connectivity between dACC and dorsomedial prefrontal cortex, and between hippocampus and insula. This connectivity was correlated negatively with sleep amount in AAs, but positively in HAs. In conclusion, the presence of clinical anxiety modulated the effects of sleep-amount on neural reactivity to negative faces differently among this group of adolescents, which may contribute to different clinical significance and outcomes of sleep disturbances in healthy adolescents and patients with anxiety disorders

The biomass of 6-years-old pines grown from mycorrhized and non-mycorrhized seedling

The research focuses on the effect of controlled mycorrhization of seedlings on growth parameters (height and diameter at the base) and biomass of Scots pine growing in two 6−year−old experimental plantations. Empirical equations were developed for the distinguished biomass fractions whose construction was based on a general formula for the allometric function

Species composition and aboveground biomass of shrubs in the understory of the Niepolomice Forest

The understory, a layer composed predominantly of shrubs that perform an important phytomeliorative function, has rarely been the subject of research on the productivity and biomass. The aim of this paper was to specify the occurrence of understory aged ≥10 years as well as its species composition and the share of individual species in the biomass in the Niepołomice Forest (S Poland). The analysed features were related to the age and site conditions of the stands. The research material consisted of dry biomass of shrubs growing within circular sample plots spaced 500 m apart from each other. Dead and live (damaged and undamaged) shrubs of dbh<7 cm were cut at a ground level to determine their wet mass and samples were taken to determine the dry mass. The mass of live shrubs was calculated based on empirical formulas. 368 sample plots were set up in total. Shrubs (13 species) were observed on 76.1% of plots. Shrubs were the most common in the stands of II and IV age groups (87% of plots). No shrubs were observed on the plots with stands older than 160 years. The most common species was Frangula alnus (56.8% of the plots). Quite common ones included Sorbus aucuparia (27.7%) and Padus avium (12.8%). Cornus sanguinea, Prunus spinosa, Salix caprea and Viburnum opulus were observed on less than 1% of the sample plots. Frangula alnus and Padus avium were inventoried in as many as 8 forest site types. The largest amount of shrubs (10 species) were observed in moist broadleaved forest stands, while the fewest (2 species) in boggy mixed broadleaved and ash−alder swamp stands. Over 56% of the aboveground biomass were live shrubs of dbh <7 cm (868.6 kg/ha), almost 29% (444.1 kg/ha) were shrubs of the dbh ≥7 cm, and around 15% (227.6 kg/ha) of the biomass were dead shrubs. The total aboveground biomass of shrubs in the understory of the analysed stands equaled, on average, to 1,540 kg/ha. 94% of the biomass was the aboveground woody biomass including bark (1,448 kg/ha). The dry mass of leaves amounted to 92 kg/ha (6%). Due to high variability of the understory biomass, the estimation error of its average amount was almost 11.4% for total biomass and 13.5% for leaves

Dry matter content in the aboveground biomass of shrubs growing in the understorey of the Niepołomice Forest stands

The aim of this paper was to determine the dry mass content in the fresh mass of leaves, trunks or branches and in the total woody aboveground biomass of shrubs forming the undergrowth of the stands in the Niepołomice Forest (southern Poland). The variability of the dry mass content in the analysed components was determined. For the prevailing species also its correlation with the individual's height and time at which samples were taken was investigated. The material comprised 744 samples, including 532 wood and 212 leaf samples, taken from the most common five shrub species: Corylus avellana, Frangula alnus, Padus avium, Padus serotina and Sorbus aucuparia. The shrubs were from 1 to 33 years old, and their height ranged from 0.3 to 9.9 m. It was shown that the dry mass content in leaves is significantly dependent on the shrub species, and in the case of F. alnus, P. avium and S. aucuparia on the height as well. The highest dry mass content was found in the leaves of C. avellana (39.3%), whereas the lowest – in F. alnus (25.5%). In case of F. alnus, the dry mass content depends on the time of sampling. The leaves collected in June had a significantly lower dry mass content than the ones sampled in subsequent months of the growing season. The dry mass content in the wood significantly depends on the shrub species and the analysed component, however the species−component interaction does not occur (tab. 4). The dry mass content in the trunk wood ranges from 50.3 (P. serotina and S. aucuparia) to 53.0% (P. avium) and exceeds that of the branch by from 1.0 (S. aucuparia) to 4.0% (P. avium). In the wood samples of F. alnus and S. aucuparia, taken between June and September, the dry mass content averaged at 47.3 and 48.7%, respectively, and was lower than in the samples taken between October and April, for which the respective means were 49.5 and 49.0%. In the case of F. alnus, the observed difference in the mean dry mass content is statistically significant at 0.05 level. The determined values of dry mass content in the fresh mass of individual components of the analysed shrubs can be used to find their dry mass as a basis for the calculation of the amount of accumulated carbon

Dynamic site index curves for Scots pine (Pinus sylvestris L.) in southern Poland

The aim of the study was to develop a site index model for Scots pine stands in southern Poland describing changes in height growth of stand's upper storey over time. The research material contained the height growth data obtained from an analysis of 189 tree stems. The collected material was used to develop the parameters of six dynamic growth equations which allowed to determine site productivity and predict changes in height growth of stands with age. Statistical criteria for assessing the accuracy of mapping empirical data and biological reasonableness were the basis of selection of the equation that best fits changes in height growth of the examined pine stands with age. The developed model can be used to predict the growth rate and determine the site index for Scots pine stands in southern Poland

Dynamic site index curves for Scots pine stands in Niepolomice Primeval Forest

The aim of the research was to evaluate, under the conditions of the Niepołomice Primeval Forest, the usefulness of site index models applied in forest practice in Poland and to develop a local system of site index curves for Scots pine. The research materials included measurement results for the trees growing on 74 circular, 0.05 ha sample plots. On the basis of the completed analyses, the age−related change in stand heights in the Niepołomice Primeval Forest is different than the height growth described by means of the site index models used in forest practice in Poland. As a result of several−stage analyses, a dynamic system of site index curves was developed for the Niepołomice Primeval Forest allowing calculation of the site index, as well as forecast of the height of stands at any age