Search results for "M function"
showing 10 items of 79 documents
The effects of long-term drainage and subsequent restoration on water table level and pore water chemistry in boreal peatlands
2014
Summary Degradation by drainage threatens biodiversity and globally important peatland ecosystem functions such as long-term carbon sequestration in peat. Restoration aims at safeguarding peatland values by recovering natural hydrology. Long-term effects of drainage and subsequent restoration, especially related to within-site variation of water table level and pore water chemistry, are poorly known. We studied hydrological variation at 38 boreal Sphagnum peatland sites (pristine, drained and restored) in Finland. The average water table level was significantly lower at Drained than Pristine sites especially near the ditches. We also observed large pore water chemical differences between Dr…
Convergence and divergence in organization of phytoplankton communities under various regimes of physical and biological control
2010
The hypothesis that physical constraints may be as important, if not more important, than biological ones in shaping the structure of phytoplankton assemblage was tested by analyzing longterm (11–29 years) phytoplankton series in eight lakes and nine sites located along a latitudinal gradient in the Northern hemisphere. Phytoplankton biomass was used and similarity of assemblages in same months of the annual data sets was then calculated by subtracting the Bray–Curtis dissimilarity index from 1. The extent of biological and physical forcing was partly based on ‘‘expert evaluation’’: the importance of four physical (light availability, temperature, conductivity, and sediment stirring up) and…
Cross-country comparisons of trends in adolescent psychosomatic symptoms : a Rasch analysis of HBSC data from four Nordic countries
2018
BACKGROUND: To analyse the psychometric properties of the HBSC Symptom Checklist (HBSC-SCL) on psychosomatic symptoms with a focus on the operating characteristics of the items, and on the impacts of measurement distortions on the comparisons of person measures across time and between countries.METHODS: Data were collected in 1993/94, 1997/98, 2001/02, 2005/06, 2008/09, 2013/14 in Denmark, Finland, Norway and Sweden as part of the Health Behaviour in School-aged Children (HBSC) study. Data comprised 116,531 students 11, 13 and 15 years old. Rasch analysis was conducted of the HBSC-SCL consisting of eight items with a focus on Differential Item Functioning (DIF) and item threshold ordering. …
Prevalence of intimate partner violence against women in Sweden and Spain: A psychometric study of the 'Nordic paradox'.
2019
The high prevalence of intimate partner violence against women (IPVAW) in countries with high levels of gender equality has been defined as the "Nordic paradox". In this study we compared physical and sexual IPVAW prevalence data in two countries exemplifying the Nordic paradox: Sweden (N = 1483) and Spain (N = 1447). Data was drawn from the European Union Agency for Fundamental Rights Survey on violence against women. To ascertain whether differences between these two countries reflect true differences in IPVAW prevalence, and to rule out the possibility of measurement bias, we conducted a set of analyses to ensure measurement equivalence, a precondition for appropriate and valid cross-cul…
Arterial stiffness, endothelial and cognitive function in subjects with type 2 diabetes in accordance with absence or presence of diabetic foot syndr…
2017
BACKGROUND: Endothelial dysfunction is an early marker of cardiovascular disease so endothelial and arterial stiffness indexes are good indicators of vascular health. We aimed to assess whether the presence of diabetic foot is associated with arterial stiffness and endothelial function impairment. METHODS: We studied 50 subjects with type 2 diabetes mellitus and diabetic foot syndrome (DFS) compared to 50 diabetic subjects without diabetic foot, and 53 patients without diabetes mellitus, by means of the mini mental state examination (MMSE) administered to evaluate cognitive performance. Carotid-femoral pulse wave velocity (PWV) and augmentation index (Aix) were also evaluated by Applanation…
The MAST FV/FE scheme for the simulation of two-dimensional thermohaline processes in variable-density saturated porous media
2009
A novel methodology for the simulation of 2D thermohaline double diffusive processes, driven by heterogeneous temperature and concentration fields in variable-density saturated porous media, is presented. The stream function is used to describe the flow field and it is defined in terms of mass flux. The partial differential equations governing system is given by the mass conservation equation of the fluid phase written in terms of the mass-based stream function, as well as by the advection-diffusion transport equations of the contaminant concentration and of the heat. The unknown variables are the stream function, the contaminant concentration and the temperature. The governing equations sy…
Validity of the Play Assessment for Group Settings: An evaluation of differential item functioning between children with specific language impairment…
2011
Aim: The purpose of this study was to evaluate the validity evidence based on internal structure of the Play Assessment for Group Settings (PAGS). Methods: The study was conducted in day care centres by comparing observations of the free play performance of two groups of children: those with specific language impairments (SLIs) (n = 55) and those with typical language development (n = 55). The participating children were 3 to 6.5 years of age. Data were subjected to many-faceted Rasch analyses and differential item functioning analysis was conducted to identify possible group-specific items in the PAGS. The effect of differentially functioning items on mean play performance measurements b…
DEVELOPMENT AND VALIDATION OF A CROSS-CULTURAL EORTC MEASURE OF SPIRITUAL WELLBEING (SWB) FOR PALLIATIVE CARE PATIENTS WITH CANCER
2014
Introduction Spiritual care and spiritual wellbeing (SWB) are central to palliative care, but no measures of SWB have yet been developed cross-culturally. Aim(s) and method(s) In 2002 the EORTC Quality of Life (QL) Group began international development of an SWB measure for palliative patients. Three domains of SWB were initially hypothesised, and items developed accordingly. Data for Phase IV field-testing and validation of the measure were collected from January 2012 to July 2013. Participants completed the 36-item provisional SWB measure and a structured debriefing interview. EORTC QLQ-C15-PAL, socio-demographic and clinical data were also collected, and a sub-set of test-retest data. Th…
A new capability index for dynamic process analysis
2013
Nowadays, the trend to produce with reduced specification limits width and at a low defectives rate seems to be irreversible. In such conditions, reliable evaluation of the process capability level represents a crucial activity to assess the quality related performance of a production process. By adopting the classical approach, such evaluation is performed by verifying the process in-control condition and by evaluating suitable capability indices. However, considering the natural dynamic behavior of production processes, i.e. the process variability over the time domain, the in-control condition characterizes only a part of the production process functioning cycle, the one with the lowest …
An item response theory analysis of response stability in personality measurement
2001
An item response theory model of response stability is developed, based on the local independence principle. The model predicts response changes under repeated administrations of the same instrument using item and examinee parameter estimates as predictors. Real data were used to assess how the model functioned. Results indicated that the model predictions were approximately fulfilled. Limitations of the model and the empirical study are discussed.