The development of path integration: combining estimations of distance and heading

Efficient daily navigation is underpinned by path integration, the mechanism by which we use self-movement information to update our position in space. This process is well-understood in adulthood, but there has been relatively little study of path integration in childhood, leading to an underrepresentation in accounts of navigational development. Previous research has shown that calculation of distance and heading both tend to be less accurate in children as they are in adults, although there have been no studies of the combined calculation of distance and heading that typifies naturalistic path integration. In the present study 5-year-olds and 7-year-olds took part in a triangle-completion task, where they were required to return to the startpoint of a multi-element path using only idiothetic information. Performance was compared to a sample of adult participants, who were found to be more accurate than children on measures of landing error, heading error, and distance error. 7-year-olds were significantly more accurate than 5-year-olds on measures of landing error and heading error, although the difference between groups was much smaller for distance error. All measures were reliably correlated with age, demonstrating a clear development of path integration abilities within the age range tested. Taken together, these data make a strong case for the inclusion of path integration within developmental models of spatial navigational processing

Structural evolution and medium-temperature thermochronology of central Madagascar: implications for Gondwana amalgamation

Madagascar occupied an important place in the amalgamation of Gondwana and preserves a record of several Neoproterozoic events that are linked to orogenesis of the East African Orogen. In this study, we integrate remote sensing, field data and thermochronology to unravel complex deformation in the Ikalamavony and Itremo domains of central Madagascar. The deformation sequence comprises a gneissic foliation (S1), followed by south- to SW-directed, tight to isoclinal, recumbent folding (D2). These are overprinted by north-trending upright folds that formed during an approximately eastwest shortening event (D3). Together these produced type 1 and type 2 fold interference patterns throughout the Itremo and Ikalamavony domains. We show that the Itremo and Ikalamavony domains were deformed together in the same orogenic system, which we interpret as the c. 630 Ma collision of Azania with Africa along the Vohibory Suture in southwestern Madagascar. In eastern Madagascar, deformation is syn- to post-550 Ma, and probably formed in response to final closure of the Mozambique Ocean along the Betsimisaraka Suture that amalgamated Madagascar with the Dharwar Craton of India. Apatite U-Pb and novel laser ablation triple quadrupole inductively coupled plasma mass spectrometry (LA-QQQ-ICP-MS) muscovite and biotite Rb-Sr thermochronology indicates that much of central Madagascar cooled through c. 500°C at c. 500 Ma

Er þörf forgangsröðunar í heilbrigðismálum? [ritstjórnargrein]

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenForgangsröðun í heilbrigðiskerfinu hefur verið nokkuð vinsælt umræðuefni undanfarið. Ég hef verið meðal þeirra sem hef gagnrýnt þessa umræðu fyrir að vera ómarkvissa, takmarkaða og oft á tíðum ruglandi (1). Færa má rök að því að heppilegt sé að skoða forgangsröðun í heilbrigðiskerfinu eins og hún eigi sér stað á nokkrum þrepum. Ástæðan er sú að umfjöllunarefni, rök, vandamál, aðferðir og lausnir eru ekki endilega þau sömu á öllum þessum þrepum. Forgangsröðun í heilbrigðiskerfinu hefur venjulega verið skipt í þrjú stig eða þrep sem eru; a) forgangsröðun í meðferð tiltekinna einstaklinga, b) forgangsröðun innan stofnana eða landsvæða og c) forgangsröðun fyrir þjóðina alla