Browsing by Subject "activity"

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  • Kallo, Henna (Helsingin yliopisto, 2021)
    During the brain development, GABAergic neurons, also referred as interneurons, migrate tangentially from the subpallium to the pallium. After intracortical dispersion, the interneurons start radial migration towards their final location in the cortex. Although the radial migration of interneurons is extensively studied, mechanisms guiding the migration remain relatively unknown. Here we studied how manipulation of cortical activity affects the radial migration and allocation of the cortical GABAergic neurons in the developing mouse brain. For this purpose, we utilized whisker trimming induced sensory deprivation in GAD67-GFP mice at postnatal days 2-5 (P2-P5) followed by cell counting in brain slices derived from P5 and P10-aged mice. In addition, we performed live-imaging of migrating neurons in organotypic cultures derived from P2 SST-TdTomato and 5HT3aR-GFP mice and cultured for 1 day in vitro. These two mouse lines roughly represent early- and late-born subpopulations of the GABAergic neurons. Live-imaging was accompanied by activity manipulations using different drugs and the Designer Receptors Exclusively Activated by Designer Drugs (DREADD) technology. Analysis of the interneurons’ allocation on the barrel cortex after the unilateral sensory deprivation revealed misallocation of GAD67+ neurons on deep cortical layers of the contralateral hemisphere of the ablation group at P5. Analysis of the tracks from the live-imaged migrating interneurons revealed altered saltatory movement behaviour of 5HT3aR+ interneurons when clozapine-N-oxide (CNO) was used to activate the electroporated GFP-GCaMP3-mCherry-hM3Dq neurons located on L2/3 of the cortex. Moreover, we observed reduced motility of migrating interneurons in the organotypic cultures treated with a KCC2 inhibitor that alters GABAA-receptor mediated transmission. Altogether, our results suggest that activity is important in promoting the radial migration of late-born interneurons during the first days of the postnatal development.
  • Simola, U.; Bonfanti, A.; Dumusque, X.; Cisewski-Kehe, J.; Kaski, S.; Corander, J. (2022)
    Context. Active regions on the photosphere of a star have been the major obstacle for detecting Earth-like exoplanets using the radial velocity (RV) method. A commonly employed solution for addressing stellar activity is to assume a linear relationship between the RV observations and the activity indicators along the entire time series, and then remove the estimated contribution of activity from the variation in RV data (overall correction method). However, since active regions evolve on the photosphere over time, correlations between the RV observations and the activity indicators will correspondingly be anisotropic. Aims. We present an approach that recognizes the RV locations where the correlations between the RV and the activity indicators significantly change in order to better account for variations in RV caused by stellar activity. Methods. The proposed approach uses a general family of statistical breakpoint methods, often referred to as change point detection (CPD) algorithms; several implementations of which are available in R and python. A thorough comparison is made between the breakpoint-based approach and the overall correction method. To ensure wide representativity, we use measurements from real stars that have different levels of stellar activity and whose spectra have different signal-to-noise ratios. Results. When the corrections for stellar activity are applied separately to each temporal segment identified by the breakpoint method, the corresponding residuals in the RV time series are typically much smaller than those obtained by the overall correction method. Consequently, the generalized Lomb-Scargle periodogram contains a smaller number of peaks caused by active regions. The CPD algorithm is particularly effective when focusing on active stars with long time series, such as alpha Cen B. In that case, we demonstrate that the breakpoint method improves the detection limit of exoplanets by 74% on average with respect to the overall correction method. Conclusions. CPD algorithms provide a useful statistical framework for estimating the presence of change points in a time series. Since the process underlying the RV measurements generates anisotropic data by its intrinsic properties, it is natural to use CPD to obtain cleaner signals from RV data. We anticipate that the improved exoplanet detection limit may lead to a widespread adoption of such an approach. Our test on the HD 192310 planetary system is encouraging, as we confirm the presence of the two hosted exoplanets and we determine orbital parameters consistent with the literature, also providing much more precise estimates for HD 192310 c.
  • the IAEA DLW database group; Careau, Vincent; Halsey, Lewis G.; Pontzer, Herman; Pietiläinen, Kirsi H. (2021)
    Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1–3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response—energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to find that energy compensation by a typical human averages 28% due to reduced BEE; this suggests that only 72% of the extra calories we burn from additional activity translates into extra calories burned that day. Moreover, the degree of energy compensation varied considerably between people of different body compositions. This association between compensation and adiposity could be due to among-individual differences in compensation: people who compensate more may be more likely to accumulate body fat. Alternatively, the process might occur within individuals: as we get fatter, our body might compensate more strongly for the calories burned during activity, making losing fat progressively more difficult. Determining the causality of the relationship between energy compensation and adiposity will be key to improving public health strategies regarding obesity.
  • Yu, Zhifeng (Helsingin yliopisto, 2015)
    Objectives. Cleantech, as an emerging new industry, its development involves the influences from various aspects. As a small to medium-sized cleantech company, the activity in China can be very challenge to study holistically. This research is aimed to provide a holistic view of the challenges and possibilities of a small to medium-size cleantech company's activity in China from the expansive learning perspectives. The purpose of this research is threefold. Firstly, it analyzes the object and network to uncover the three historical phases of GreenStream's long trajectory leaning process. Secondly, it analyzes learning actions and contradictions to uncover the driving forces of development and the expansiveness of the activity. Thirdly, based on the historical analysis an analysis of expansive learning cycles is made, with the purpose to sketch the zone of proximal development across the learning cycles and address the future possibilities and challenges. Methods. The research case Company is GreenStream, a small to medium-sized Finnish cleantech company in China. 8 Interviewees were chose from the different parties involved in its China activity. 4 of the interviewees from the case company GreenStream, 1 interviewee from its Chinese partner, and 3 interviewees from the third parties. The data is firstly analyzed by the historical analysis, namely analysis of object of activity system and analysis of network, following the analysis of expansive learning cycles, namely analysis of learning steps and analysis of learning actions and analysis of developmental contradictions. The zone of proximal development is sketched based on the historical analysis and analysis of expansive learning cycles. Results and conclusions. Interesting findings emerge through the systematic analysis. Three historical analyses reveals the object and network transformed in 3 phases. The object has transformed in 3 historical phases with the unchanged main motivation, the evolving economic imperative, and other emerging forces from different element of the activity. The partnership activity emerged and consolidated with the network development. Object formation and network development thus form the criteria to divide the 3 historical phases from "Small Spark in China", to " Great Success in China" and then to "Standing on Two Feet in China". Analysis of expansive learning cycles reveals that the 3 historical phases contours 3 expansive learning cycles. The first learning cycle was disrupted, the second learning cycle completed and expanded, and the third learning cycle is under development. Each learning cycle has its own character, and within each learning cycle, different levels of contradictions emerged as the driving forces of the development of GreenStream. Through tracing different levels of contradictions through the 3 expansive learning cycles, the expansiveness of GreenStream's activity could be detected with regard to the expansion of the object and expansion over interruption. Object formation, partnership and policy over clean-tech industry become important three elements for the zone of proximal development of GreenStream's activity in China. Through the understanding of these dynamics and momentum of the China activity in the past and present by means of expansive learning aspects, the subject can better master and build the development of the activity system in the future.
  • Willamo, Teemu Einari; Hackman, Thomas; Lehtinen, Jyri; Käpylä, Maarit; Olspert, Nigul; Viviani, Mariangela; Warnecke, Jörn (2020)
    Context.Magnetic activity cycles are an important phenomenon both in the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, but not much attention has been paid to the shape of cycles in other stars. Aims.Our aim is to study whether the asymmetric shape of the solar cycle is common in other stars as well, and compare the cycle asymmetry to other stellar parameters. We also study the differences in the shape of the solar cycle, depending on the activity indicator that is used. The observations are also compared to simulated activity cycles. Methods.We used the chromospheric Ca II H&K data from the Mount Wilson Observatory HK Project. In this data set, we identified 47 individual cycles from 18 stars. We used the statistical skewness of a cycle as a measure of its asymmetry, and compared this to other stellar parameters. A similar analysis has been performed for magnetic cycles extracted from direct numerical magnetohydrodynamic simulations of solar-type convection zones. Results.The shape of the solar cycle (fast rise and slower decline) is common in other stars as well, although the Sun seems to have particularly asymmetric cycles. Cycle-to-cycle variations are large, but the average shape of a cycle is still fairly well represented by a sinusoid, although this does not take its asymmetry into account. We find only slight correlations between the cycle asymmetry and other stellar parameters. There are large differences in the shape of the solar cycle, depending on the activity indicator that is used. The simulated cycles differ in the symmetry of global simulations that cover the full longitudinal range and are therefore capable of exciting non-axisymmetric large-scale dynamo modes, and wedge simulations that cover a partial extent in longitude, where only axisymmetric large-scale modes are possible. The former preferentially produce positive and the latter negative skewness.
  • Dixneuf, Charly; Peiris, Parami; Nummi, Petri; Sundell, Janne (2021)
    Biodiversity and habitats are under threat from many factors such as human population increase, habitat loss, fragmentation, and climate change. In freshwater habitats, including wetlands, biodiversity is expected to decline on a greater scale than in terrestrial ecosystems. Ephemeral wetlands are little studied habitats compared to other wetlands, such as permanent lakes and rivers. The purpose of this study was to investigate the vertebrate fauna present by ephemeral vernal pools and to see whether vernal pools increase the activity and diversity of vertebrates in a boreal forest ecosystem in northern Europe. We studied the activity and species richness of birds and mammals with direct observations, camera traps, feces tracking, and snap-trapping by ten vernal pools and ten permanent wetlands. Bird activity was higher in the spring period in vernal pools than in permanent wetlands. For large mammals, both activity and species richness were greater around vernal pools than by permanent wetlands. Of individuals species, the moose (Alces alces), roe deer (Capreolus capreolus), and hares (Lepus europaeus and Lepus timidus) used vernal pools significantly more between seasons compared to permanent wetlands. Small mammal activity was higher by vernal pools in April, while in May and June the pattern reversed. In the light of these results, vernal pools seem to have different importance and use depending on the vertebrate group, e.g., for sheltering, foraging, resting, nesting, or thermoregulation.
  • Norring, M.; Valros, A.; Valaja, J.; Sihvo, H-K; Immonen, K.; Puolanne, E. (2019)
    Wooden breast myopathy, a condition where broiler breast muscles show a hardened consistency post-mortem, has been described recently. However, it is not known how wooden breast myopathy affects the bird activity or welfare. Altogether, over 340 birds of five commonly used commercial hybrids were housed in 25 pens, and sample birds killed at ages of 22, 32, 36, 39 and 43 days. Their breast muscle condition was assessed post-mortem by palpation. The birds were gait scored and their latency to lie was measured before killing. For further behavior observations, one affected and healthy bird in 12 pens were followed on 5 days for 20 minutes using video recordings. The connection of myopathy to gait score and activity was analyzed with mixed models. A higher gait score of wooden-breast-affected birds than that of unaffected birds (2.9 +/- 0.1 v. 2.6 +/- 0.1, P <0.05) indicated a higher level of locomotor difficulties over all age groups. The wooden-breast-affected birds had fewer crawling or movement bouts while lying down compared with unaffected (P <0.05). Wooden breast myopathy-affected birds were heavier (2774 +/- 91 v. 2620 +/- 91 g; P <0.05) and had higher breast muscle yield (21 +/- 1 v. 19 +/- 1%; P <0.05) than unaffected birds overall. Older birds had longer lying bouts, longer total lying time, fewer walking bouts, more difficulties to walk and to stand compared with younger birds (P <0.05). Birds with poorer gait had longer total lying time and fewer walking bouts (P <0.05). Birds with greatest breast muscle yield had the largest number of lying bouts (P <0.05). It was concluded that wooden breast myopathy was associated with an impairment of gait scores, and may thus be partly linked to the common walking abnormalities in broilers.
  • Malin, Minna-Helena (Helsingfors universitet, 2010)
    One of the biggest challenges in Finland in the future will be the growing number of elderly people. It means that more and more people will be dependent on care and medication. According to research elderly people consider physical working order and an option for social interaction with other people to be the most important things for their well-being. As one ages the activity of living decreases. As a result other matters relating to the quality of life suffer as well. Older people are entitled to life worthy of a human being. To underpin this objective we have to maintain their independence and activity. This requires a certain level of health, well-being and working order which can all be influenced by other people. All activities are surrounded by some sort of an environment, so it is an important part of well-being. Green environment in particular is believed to have a positive effect to the well being and health. This is emphasized in hospitals and institutions. The first aim of this study was to map out the factors in green environment that motivate and encourage to use more time outdoors. The second aim was to study the impacts of the increased activity for the elderly people in the assisted living building Palta in Paimio, Finland. The research was carried out during summer 2009. Method was to observe the use of green environment and to interview nine habitants and their relatives and the staff of Paltanpuisto. The habitants were interviewed twice, spring and autumn. Other participants were interviewed once late summer. The object was to find out what were the reasons that got the habitants to go out and how did they feel it had affected their well-being The results were organized into three categories that were considered to activate habitants to go out: Safety, operationality and experientiality. The categories are interactive and in part overlapping. Experiences of well-being were considered as one category, which once again interacts with the three mentioned above. Main reasons to go out were the feeling of independence, other people and the affect going out has on general mood. In general this study confirms that green environment has a positive affect for the habitants of assisted living buildings. Most habitants saw the opportunity to go out as a vitally important factor behind good quality of life.