Nonlinear association structures in flexible Bayesian additive joint models

Joint models of longitudinal and survival data have become an important tool for modeling associations between longitudinal biomarkers and event processes. The association between marker and log-hazard is assumed to be linear in existing shared random effects models, with this assumption usually remaining unchecked. We present an extended framework of flexible additive joint models that allows the estimation of nonlinear, covariate specific associations by making use of Bayesian P-splines. Our joint models are estimated in a Bayesian framework using structured additive predictors for all model components, allowing for great flexibility in the specification of smooth nonlinear, time-varying and random effects terms for longitudinal submodel, survival submodel and their association. The ability to capture truly linear and nonlinear associations is assessed in simulations and illustrated on the widely studied biomedical data on the rare fatal liver disease primary biliary cirrhosis. All methods are implemented in the R package bamlss to facilitate the application of this flexible joint model in practice.Comment: Changes to initial commit: minor language editing, additional information in Section 4, formatting in Supplementary Informatio

Investigadors de l'ICP expliquen la fisiologia del Myotragus balearicus

Els investigadors Meike Köhler i Salvador Moyà, de l'Institut Català de Paleontologia (ICP-UAB), han donat a conèixer els resultats d'una recerca molt innovadora en el camp de la paleontologia. Mitjançant l'ús de tècniques paleohistològiques han pogut inferir la fisiologia d'espècies extingides. L'estudi, basat en el bòvid endèmic de Illes Balears Myotragus, es publica a la prestigiosa revista científica "Proceedings of the National Academy of Science" (PNAS).Los investigadores Meike Köhler y Salvador Moyà, del Institut Català de Paleontologia (ICP-UAB), han dado a conocer los resultados de una investigación muy innovadora en el campo de la paleontología. Mediante el uso de técnicas paleohistológicas han podido inferir la fisiología de especies extinguidas. El estudio, basado en el bóvido endémico Myotragus balearicus, se publica en la prestigiosa revista científica "Proceedings of the National Academy of Science" (PNAS).Researchers Meike Köhler and Salvador Moyà, from the Institut Català de Paleontologia (ICP-UAB) have released the results of a highly innovative research in the field of paleontology. Using palaeohistological techniques, they were able to infer the physiology of extinct species. The study, based on the goat-like bovidae Myotragus from the Balearic Islands, has been published in the prestigious scientific journal Proceedings of the National Academy of Science (PNAS)

Ebusia moralesi n. gen. nov. sp, a new endemic caprine (Bovidae, Mammalia) from the Neogene of Eivissa Island (Balearic Islands, Western Mediterranean) : evolutionary implications

We describe the first endemic large mammal from the Neogene of the Island Eivissa (Balearic Islands, Spain), a new genus and species of an endemic insular bovid, Ebusia n. gen. moralesi n. sp. (Artiodactyla, Caprini). This new taxon is the smallest caprine currently described and shows primitive, continental-like complete dentition. It has a long and complex lower p2 and upper P2 and P3, long premolar series, non-hypsodont incisors and a moderate degree of hypsodonty of the check teeth. The long bones (in particular the tibia) are rather slender, similar to those of continental bovids. However, the metapodials show an intermediate degree of shortening between continental bovids and Myotragus species and other insular ruminants. The few derived insular adaptations of Ebusia n. gen. suggest that this taxon probably represents the first phase of isolation. The morphology of the dentition and postcranial is characteristic of Caprini and similar to that of the Myotragus/Nesogoral group. This suggests that E. moralesi would be close to the ancestral continental pattern of the endemic Neogene-Quaternary caprine lineage that colonised the western Mediterranean Islands during the Messinian salinity crisis

Quality assessment of spaceborne sea surface salinity observations over the northern North Atlantic

Spaceborne sea surface salinity (SSS) measurements provided by the European Space Agency's (ESA) “Soil Moisture and Ocean Salinity” (SMOS) and the National Aeronautical Space Agency's (NASA) “Aquarius/SAC-D” missions, covering the period from May 2012 to April 2013, are compared against in situ salinity measurements obtained in the northern North Atlantic between 20°N and 80°N. In cold water, SMOS SSS fields show a temperature-dependent negative SSS bias of up to −2 g/kg for temperatures <5°C. Removing this bias significantly reduces the differences to independent ship-based thermosalinograph data but potentially corrects simultaneously also other effects not related to temperature, such as land contamination or radio frequency interference (RFI). The resulting time-mean bias, averaged over the study area, amounts to 0.1 g/kg. A respective correction applied previously by the Jet Propulsion Laboratory to the Aquarius data is shown here to have successfully removed an SST-related bias in our study area. For both missions, resulting spatial structures of SSS variability agree very well with those available from an eddy-resolving numerical simulation and from Argo data and, additionally they also show substantial salinity changes on monthly and seasonal time scales. Some fraction of the root-mean-square difference between in situ, and SMOS and Aquarius data (approximately 0.9 g/kg) can be attributed to short time scale ocean processes, notably at the Greenland shelf, and could represent associated sampling errors there

Labelling experiments in red deer provide a general model for early bone growth dynamics in ruminants

Altres ajuts: CERCA Programme/Generalitat de CatalunyaGrowth rates importantly determine developmental time and are, therefore, a key variable of a species' life history. A widely used method to reconstruct growth rates and to estimate age at death in extant and particularly in fossil vertebrates is the analysis of bone tissue apposition rates. Lines of arrested growth (LAGs) are of special interest here, as they indicate a halt in bone growth. However, although of great importance, the time intervals between, and particularly the reason of growth arrests remains unknown. Therefore, experiments are increasingly called for to calibrate growth rates with tissue types and life history events, and to provide reliable measurements of the time involved in the formation of LAGs. Based on in vivo bone labelling, we calibrated periods of bone tissue apposition, growth arrest, drift and resorption over the period from birth to post-weaning in a large mammal, the red deer. We found that bone growth rates tightly matched the daily weight gain curve, i.e. decreased with age, with two discrete periods of growth rate disruption that coincided with the life history events birth and weaning, that were visually recognisable in bone tissue as either partial LAGs or annuli. Our study identified for the first time in a large mammal a general pattern for juvenile bone growth rates, including periods of growth arrest. The tight correlation between daily weight gain and bone tissue apposition suggests that the red deer bone growth model is valid for ruminants in general where the daily weight gain curve is comparable

Dental histology of late Miocene hipparionins compared with extant Equus, and its implications for Equidae life history

Hipparionins were a dominant element of the late Miocene faunas of Europe; however, their biology and ecology remain incompletely understood. In this paper, we explore the pace of life history of different-sized hipparionin horses, using dental histology, and compare it with extant equids. In doing so we consider (i) the size diversity of hipparionins, (ii) their generally smaller size compared to extant equids, and (iii) the allometric coupling between size and life history. In particular, we reconstruct the dental growth in lower first/second molars and in later-formed lower third molars for three hipparionin taxa: two dwarf species (Hipparion periafricanum and H. gromovae), and a larger species (H. concudense). We also analyze dental growth in an extant zebra (Equus quagga) for comparative purposes. Our results reveal that, within each species, there are differences in enamel growth parameters between the first/second molars and third molars. These results illustrate the differences in the developmental timing of these teeth and the existence of a relationship between dental growth parameters with somatic growth. We also find that hipparionin teeth grow at slower rates and tend to erupt later in time than in extant Equus. Dwarf hipparionins, moreover, exhibit lower enamel extension rates than the larger species, but similar formation and eruption times. Considering the link between dental development and life history, these results suggest a slower pace of growth of selected hipparionins compared to extant equids, and a further slower life history than expected for their size in the two dwarf forms

Ein Vergleich traditioneller und computergestützter Methoden zur Erstellung einer deutschsprachigen Need for Cognition Kurzskala

Die vorliegende Arbeit dient der Entwicklung einer Kurzskala zur Messung von Need for Cognition (NFC). Neben traditionellen Verfahren der Itemreduktion auf Basis von Itemkennwerten der klassischen Testtheorie wurde in Studie 1 (N = 282) ein neues, computergestütztes Verfahren des "full information approach" vorgestellt. Mithilfe der beiden Verfahren wurden 3 mögliche Skalen mit jeweils 5 Items selektiert, welche in einem unabhängigen Datensatz in Studie 2 (N = 530) Validierungskriterien unterzogen wurden. Aus den 3 Skalen mit ähnlichen Ergebnissen bezüglich der Gütekriterien wurde eine anhand der "full information approach" erstellten Skalen als finale Kurzskala NFC-K ausgewählt. Diese NFC-K weist ein Cronbachs α von .69 auf, eine Korrelation mit der Langskala von .81 und keinen signifikanten Zusammenhang mit sozialer Erwünschtheit. Neben der systematischen und objektiven Selektion und Validierung der Kurzskala NFC-K stellt die vorliegende Arbeit auch eine Fallstudie zu den Herausforderungen der Kurzskalenentwicklung auf Basis klassischer und computergestützter Selektionsverfahren dar. (DIPF/Orig.)The current study presents the development and validation of a Need for Cognition (NFC) short scale. In Study 1 (N = 282), traditional item selection procedures based on classic test theory were used as well as an innovative computational approach, our "full information approach." The procedures led to three different short scales with comparable psychometric quality, which were validated in Study 2 (N = 530). Based on different validation criteria, one of the three scales obtained from the full information approach was selected as the final short scale NFC-K. This NFC-K achieved a Cronbach\u27s α of .69, a correlation of .81 with the original scale, and showed no significant correlation with social desirability. Besides presenting a systematic and objective selection and validation of the NFC-K, this article represents a case study of the challenges of developing a short scale comparing both traditional and computational approaches. (DIPF/Orig.

Insular giant leporid matured later than predicted by scaling

The island syndrome describes morphological, behavioral, and life history traits that evolve in parallel in endemic insular organisms. A basic axiom of the island syndrome is that insular endemics slow down their pace of life. Although this is already confirmed for insular dwarfs, a slow life history in giants may not be adaptive, but merely a consequence of increasing body size.We tested this question in the fossil insular giant leporid Nuralagus rex. Using bone histology, we constructed both a continental extant taxon model derived from experimentally fluorochrome-labeled Lepus europaeus to calibrate life history events, and a growth model for the insular taxon. N. rex grew extremely slowly and delayed maturity well beyond predictions from continental phylogenetically corrected scaling models. Our results support the life history axiom of the island syndrome as generality for insular mammals, regardless of whether they have evolved into dwarfs or giants