237 research outputs found

    Measurement invariance in the social sciences:Historical development, methodological challenges, state of the art, and future perspectives

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    This review summarizes the current state of the art of statistical and (survey) methodological research on measurement (non)invariance, which is considered a core challenge for the comparative social sciences. After outlining the historical roots, conceptual details, and standard procedures for measurement invariance testing, the paper focuses in particular on the statistical developments that have been achieved in the last 10 years. These include Bayesian approximate measurement invariance, the alignment method, measurement invariance testing within the multilevel modeling framework, mixture multigroup factor analysis, the measurement invariance explorer, and the response shift-true change decomposition approach. Furthermore, the contribution of survey methodological research to the construction of invariant measurement instruments is explicitly addressed and highlighted, including the issues of design decisions, pretesting, scale adoption, and translation. The paper ends with an outlook on future research perspectives.</p

    Latent Markov Latent Trait Analysis for Exploring Measurement Model Changes in Intensive Longitudinal Data

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    Drawing inferences about dynamics of psychological constructs from intensive longitudinal data requires the measurement model (MM)—indicating how items relate to constructs—to be invariant across subjects and time-points. When assessing subjects in their daily life, however, there may be multiple MMs, for instance, because subjects differ in their item interpretation or because the response style of (some) subjects changes over time. The recently proposed “latent Markov factor analysis” (LMFA) evaluates (violations of) measurement invariance by classifying observations into latent “states” according to the MM underlying these observations such that MMs differ between states but are invariant within one state. However, LMFA is limited to normally distributed continuous data and estimates may be inaccurate when applying the method to ordinal data (e.g., from Likert items) with skewed responses or few response categories. To enable researchers and health professionals with ordinal data to evaluate measurement invariance, we present “latent Markov latent trait analysis” (LMLTA), which builds upon LMFA but treats responses as ordinal. Our application shows differences in MMs of adolescents’ affective well-being in different social contexts, highlighting the importance of studying measurement invariance for drawing accurate inferences for psychological science and prac

    Reciprocity as a foundation of financial economics

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    This paper argues that the subsistence of the fundamental theorem of contemporary financial mathematics is the ethical concept ‘reciprocity’. The argument is based on identifying an equivalence between the contemporary, and ostensibly ‘value neutral’, Fundamental Theory of Asset Pricing with theories of mathematical probability that emerged in the seventeenth century in the context of the ethical assessment of commercial contracts in a framework of Aristotelian ethics. This observation, the main claim of the paper, is justified on the basis of results from the Ultimatum Game and is analysed within a framework of Pragmatic philosophy. The analysis leads to the explanatory hypothesis that markets are centres of communicative action with reciprocity as a rule of discourse. The purpose of the paper is to reorientate financial economics to emphasise the objectives of cooperation and social cohesion and to this end, we offer specific policy advice

    Autoimmune cirrhosis treated by liver transplantation using the right hepatic lobe from a living related donor

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    peer reviewedThe authors describe the case of a 17-year-old girl who suffered from end-stage liver failure due to chronic autoimmune hepatitis. Liver failure was complicated by severe portal hypertension, hypersplenism and refractory ascites. Liver transplantation was indicated. She was listed for cadaveric whole liver transplantation, but her infrequent blood group (B) increased waiting time. Her condition deteriorated to Child C liver failure and living related liver transplant was considered. Her father was compatible and proposed himself for donation. Right lobe procurement was decided in order to provide sufficient liver mass. No transfusion of red cells, platelets, or fresh frozen plasma was used either in the donor or the recipient. Both recipient and donor left the ward at postoperative day 14, without complication. They were both asymptomatic and with normal liver tests at one year follow-up. Living related liver transplantation using the right lobe may offer an alternative to liver transplant candidates in this period of organ donor shortage

    Clinical Case of the Month. Autoimmune Cirrhosis Treated by Liver Transplantation Using the Right Hepatic Lobe from a Living Related Donor

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    peer reviewedThe authors describe the case of a 17-year-old girl who suffered from end-stage liver failure due to chronic autoimmune hepatitis. Liver failure was complicated by severe portal hypertension, hypersplenism and refractory ascites. Liver transplantation was indicated. She was listed for cadaveric whole liver transplantation, but her infrequent blood group (B) increased waiting time. Her condition deteriorated to Child C liver failure and living related liver transplant was considered. Her father was compatible and proposed himself for donation. Right lobe procurement was decided in order to provide sufficient liver mass. No transfusion of red cells, platelets, or fresh frozen plasma was used either in the donor or the recipient. Both recipient and donor left the ward at postoperative day 14, without complication. They were both asymptomatic and with normal liver tests at one year follow-up. Living related liver transplantation using the right lobe may offer an alternative to liver transplant candidates in this period of organ donor shortage

    Tertiary hypothyroidism in a dog

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    <p/> <p>A nine-year-old male entire Labrador was diagnosed with pituitary dependent hyperadrenocorticism. Following seven months of successful mitotane therapy, the dog presented with marked weight gain, seborrhoea and alopecia. Routine clinicopathological analyses revealed marked hypercholesterolaemia. Serum total and free thyroxine (T4) concentrations were below their respective reference ranges. Serum thyroid stimulating hormone (cTSH) concentration was within reference range. TSH and thyrotropin releasing hormone (TRH) response tests revealed adequate stimulation of total T4 in both, and cTSH in the latter test. Magnetic resonance imaging revealed a mass arising from the pituitary fossa, with suprasellar extension. A diagnosis of tertiary hypothyroidism was made. Following four weeks of levothyroxine therapy, circulating cholesterol concentration had declined, weight loss had ensued and dermatological abnormalities had improved. Euthanasia was performed four months later due to the development of neurological signs. A highly infiltrative pituitary adenoma, with effacement of the overlying hypothalamus was identified on post mortem examination. Tertiary hypothyroidism has not been previously reported in dogs.</p

    pKa Modulation of the Acid/Base Catalyst within GH32 and GH68: A Role in Substrate/Inhibitor Specificity?

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    Glycoside hydrolases of families 32 (GH32) and 68 (GH68) belong to clan GH-J, containing hydrolytic enzymes (sucrose/fructans as donor substrates) and fructosyltransferases (sucrose/fructans as donor and acceptor substrates). In GH32 members, some of the sugar substrates can also function as inhibitors, this regulatory aspect further adding to the complexity in enzyme functionalities within this family. Although 3D structural information becomes increasingly available within this clan and huge progress has been made on structure-function relationships, it is not clear why some sugars bind as inhibitors without being catalyzed. Conserved aspartate and glutamate residues are well known to act as nucleophile and acid/bases within this clan. Based on the available 3D structures of enzymes and enzyme-ligand complexes as well as docking simulations, we calculated the pKa of the acid-base before and after substrate binding. The obtained results strongly suggest that most GH-J members show an acid-base catalyst that is not sufficiently protonated before ligand entrance, while the acid-base can be fully protonated when a substrate, but not an inhibitor, enters the catalytic pocket. This provides a new mechanistic insight aiming at understanding the complex substrate and inhibitor specificities observed within the GH-J clan. Moreover, besides the effect of substrate entrance on its own, we strongly suggest that a highly conserved arginine residue (in the RDP motif) rather than the previously proposed Tyr motif (not conserved) provides the proton to increase the pKa of the acid-base catalyst
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