1,093 research outputs found
Determination of till hydraulic properties for modelling flow and solute transport in a forested hillslope
Water and nitrogen processes along a typical water flowpath and streamwater exports from a forested catchment and changes after clear-cutting: a modelling study
International audienceA two dimensional model, FEMMA, to describe water and nitrogen (N) fluxes within and from a forested first-order catchment (Kangasvaara in Eastern Finland) was constructed by linking the most significant processes affecting the fluxes of water, ammonium, nitrate and dissolved organic nitrogen along a hillslope from the water divide to the stream. The hillslope represents the average flowpath of water in the catchment and the model was used to estimate the N fluxes for a catchment in eastern Finland before and after clear-cutting. The simulated results were in reasonable agreement with the nitrate, dissolved organic N and dissolved total N measurements from the study catchment and with other results in the literature. According to the simulations, the major sinks of N after clear-cutting were immobilisation by soil microbes, uptake by ground vegetation and sorption to soil. These sinks increased downslope from the clear-cut area, indicating the importance of an uncut buffer zone between the stream and the clear-cut area in reducing N exports. The buffer zone retained 76% of the N flux coming from the clear-cut area. Nitrification was a key process in controlling the N export after clear-cutting and N increases were mainly as nitrate. Most of the annual N export took place during the spring flood, when uptake of N by plants was minimal
Low schoolwork engagement and schoolwork difficulties predict smoking in adolescence?
Low academic achievement has been associated with smoking but factors behind this association are poorly known. Such factors could include schoolwork disengagement and schoolwork difficulties. To assess the extent to which they contribute to the explanation of how health inequalities emerge, we study in a longitudinal design whether these have an independent effect on smoking or whether their effect is mediated through academic achievement. Longitudinal data were collected in the Helsinki metropolitan area, Finland in 2011 and 2014. Participants were seventh-graders (12 13 years, N=9497). In the follow-up, 6534 students reported their smoking status in the ninth grade (15 16 years). Smoking, schoolwork behavioural engagement, i.e. participation in academic activities, and disengagement, schoolwork difficulties and cognitive competence were self-reported by adolescents. Academic achievement was obtained from the Finnish national application register on upper secondary education. A mediation analysis was executed with bootstrapped confidence intervals. Higher schoolwork behavioural engagement and cognitive competence in the seventh grade predicted that adolescents were more likely not to smoke in the ninth grade (all P <0.001) while higher schoolwork disengagement and schoolwork difficulties predicted adolescents smoking (all P <0.001). The effects were mediated through academic achievement. Students behavioural disengagement with schoolwork and schoolwork difficulties are risks for smoking initiation. Their effect is mediated through poor school achievement. As smoking often continues in adulthood and poor school performance typically leads to lower education, schoolwork disengagement and difficulties in adolescence constitute potential pathways to inequalities in health.Peer reviewe
A quasi-three-dimensional model for predicting rainfall-runoff processes in a forested catchment in Southern Finland
International audienceRunoff generation in a forested catchment (0.18 km2) was simulated using a quasi-three-dimensional rainfall-runoff model. The model was formulated over a finite grid where water movement was assumed to be dominantly vertical in the unsaturated soil zone and horizontal in the saturated soil. The vertical soil moisture distribution at each grid cell was calculated using a conceptual approximation to the one-dimensional Richards equation. The approximation allowed the use of a simple soil surface boundary condition and an efficient solution to the water table elevation over the finite grid. The approximation was coupled with a two-dimensional ground water model to calculate lateral soil water movement between the grid cells and exfiltration over saturated areas, where runoff was produced by the saturation-excess mechanism. Runoff was an input to a channel network, which was modelled as a nonlinear reservoir. The proposed approximation for the vertical soil moisture distribution in unsaturated soil compared well to a numerical solution of the Richards equation during shallow water table conditions, but was less satisfactory during prolonged dry periods. The simulation of daily catchment outflow was successful with the exception of underprediction of extremely high peak flows. The calculated water table depth compared satisfactorily with the measurements. An overall comparison with the earlier results of tracer studies indicated that the modelled contribution of direct rainfall/snowmelt in streamflow was higher than the isotopically traced fraction of event-water in runoff. The seasonal variation in the modelled runoff-contributing areas was similar to that in the event-water-contributing areas from the tracer analysis
Perceived stress across the midlife: longitudinal changes among a diverse sample of women, the Study of Women’s health Across the Nation (SWAN)
Abstract
Background
In women, midlife is a period of social and physiological change. Ostensibly stressful, cross-sectional studies suggest women experience decreasing stress perceptions and increasing positive outlook during this life stage. The aim of this paper was to describe the longitudinal changes in perceived stress as women transitioned through the midlife.
Methods
Premenopausal women (n = 3044) ages 42–52 years at baseline, were recruited from seven sites in the Study of Women’s Health Across the Nation, and followed approximately annually over 13 visits with assessment of perceived stress and change in menopausal status. Longitudinal regression models were used to assess the effects of age, menopausal status and baseline sociodemographic variables on the trajectory of perceived stress over time.
Results
At baseline, mean age was 46.4 ± 2.7 years; participants were white (47%), black (29%), Hispanic (7%), Japanese (9%), or Chinese (8%). Hispanic women, women with lesser educational attainment, and women reporting financial hardship were each more likely to report high perceived stress levels at baseline (all p < 0.0001). After adjustment for baseline sociodemographic factors, perceived stress decreased over time for most women (p < 0.0001), but increased for both Hispanic and white participants at the New Jersey site (p < 0.0001). Changing menopausal status was not a significant predictor of perceived stress.
Conclusions
Self-reported stress decreased for most women as they transitioned across the midlife; changing menopausal status did not play a significant role after adjustment for age and sociodemographic factors. Future studies should explore the stress experience for women by racial / ethnic identity and demographics.https://deepblue.lib.umich.edu/bitstream/2027.42/142790/1/40695_2018_Article_32.pd
Moving toward a prevention strategy for osteoporosis by giving a voice to a silent disease
Abstract
A major unmet challenge in developing preventative treatment programs for osteoporosis is that the optimal timing of treatment remains unknown. In this commentary we make the argument that the menopausal transition (MT) is a critical period in a woman’s life for bone health, and that efforts aimed at reducing fracture risk later in life may benefit greatly from strategies that treat women earlier with the intent of keeping bones strong as long as possible. Bone strength is an important parameter to monitor during the MT because engineering principles can be applied to differentiate those women that maintain bone strength from those women that lose bone strength and are in need of early treatment. It is critical to understand the underlying mechanistic causes for reduced strength to inform treatment strategies. Combining measures of strength with data on how bone structure changes during the MT may help differentiate whether a woman is losing strength because of excessive bone resorption, insufficient compensatory bone formation, trabeculae loss, or some combination of these factors. Each of these biomechanical mechanisms may require a different treatment strategy to keep bones strong. The technologies that enable physicians to differentially diagnose and treat women in a preventive manner, however, have lagged behind the development of prophylactic treatments for osteoporosis. To take advantage of these treatment options, advances in preventive treatment strategies for osteoporosis may require developing new technologies with imaging resolutions that match the pace by which bone changes during the MT and supplementing a woman's bone mineral density (BMD)-status with information from engineering-based analyses that reveal the structural and material changes responsible for the decline in bone strength during the menopausal transition.http://deepblue.lib.umich.edu/bitstream/2027.42/134529/1/40695_2016_Article_16.pd
What influences the speed of prototyping? An empirical investigation of twenty software startups
It is essential for startups to quickly experiment business ideas by building
tangible prototypes and collecting user feedback on them. As prototyping is an
inevitable part of learning for early stage software startups, how fast
startups can learn depends on how fast they can prototype. Despite of the
importance, there is a lack of research about prototyping in software startups.
In this study, we aimed at understanding what are factors influencing different
types of prototyping activities. We conducted a multiple case study on twenty
European software startups. The results are two folds, firstly we propose a
prototype-centric learning model in early stage software startups. Secondly, we
identify factors occur as barriers but also facilitators for prototyping in
early stage software startups. The factors are grouped into (1) artifacts, (2)
team competence, (3) collaboration, (4) customer and (5) process dimensions. To
speed up a startups progress at the early stage, it is important to incorporate
the learning objective into a well-defined collaborative approach of
prototypingComment: This is the author's version of the work. Copyright owner's version
can be accessed at doi.org/10.1007/978-3-319-57633-6_2, XP2017, Cologne,
German
Production of a C-15 radioactive ion beam based on O-18(n, alpha)
.In the context of the SPIRAL2 radioactive beam facility the production rate of the neutron-rich C-15 nucleus by O-18(n,) has been investigated. In a water target of 20 cm(3), enriched in O-18 and placed behind the neutron converter, a rate of a few 10(10) nuclei per second can be reached with 1mA of 40MeV deuterons. A O-18(n,) cross-section based on the activation method is proposed. It is intermediate between the highest and lowest evaluations available to date.Peer reviewe
Participative Facility Planning for Obstetrical and Neonatal Care Processes: Beginning of Life Process
Introduction. Old hospitals may promote inefficient patient care processes and safety. A new, functionally planned hospital presents a chance to create an environment that supports streamlined, patient-centered healthcare processes and adapts to users' needs. This study depicts the phases of a facility planning project for pregnant women and newborn care processes (beginning of life process) at Turku University Hospital. Materials and Methods. Project design reports and meeting documents were utilized to assess the beginning of life process as well as the work processes of the Women's and Children's Hospital. Results. The main elements of the facility design (FD) project included rigorous preparation for the FD phase, functional planning throughout the FD process, and setting key values: (1) family-centered care, (2) Lean thinking and Lean tools as the framework for the FD process, (3) safety, and (4) cooperation. Conclusions. A well-prepared FD project with sufficient insight into functional planning, Lean thinking, and user-centricity seemed to facilitate the actual FD process. Although challenges occurred, the key values were not forgone and were successfully incorporated into the new hospital building
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