Diffusion Means and Heat Kernel on Manifolds

We introduce diffusion means as location statistics on manifold data spaces. A diffusion mean is defined as the starting point of an isotropic diffusion with a given diffusivity. They can therefore be defined on all spaces on which a Brownian motion can be defined and numerical calculation of sample diffusion means is possible on a variety of spaces using the heat kernel expansion. We present several classes of spaces, for which the heat kernel is known and sample diffusion means can therefore be calculated. As an example, we investigate a classic data set from directional statistics, for which the sample Fr\'echet mean exhibits finite sample smeariness.Comment: 8 pages, 1 figure, conference paper submitted to GSI 202

Værdiskabende workshops – trin for trin

Herunder anmeldes: Wirenfeldt Jensen, T., & Albrechtsen, C. (2022). Værdiskabende workshops: Trin for trin. Samfundslitteratur. Står du og evt. dine kolleger over for at skulle forberede og afholde en workshop, så er der hjælp at hente i bogen ”Værdiskabende workshops – trin for trin”. Bogen henvender sig til alle – lige fra de uerfarne workshopledere, travle projektledere til undervisere, der bare gerne vil have en kortfattet og konkret indføring til, hvordan en værdiskabende workshop kan gennemføres fra start til slut

Viking Age garden plants from southern Scandinavia: diversity, taphonomy and cultural aspects

Plant finds recovered from archaeological sites in southern Scandinavia dated to the Viking Age reflect the diversity of useful plants that were cultivated and collected. This review presents the results of 14 investigations of deposits that are dated between AD 775 and 1050. The site types are categorized as agrarian, urban, military and burials. Garden plants are unevenly distributed, as the greatest diversity is recorded in features from urban contexts. We argue that taphonomic processes played an important role in the picture displayed. Archaeobotanical research results from neighbouring regions suggest that Viking Age horticulture has its roots in older traditions, and that the spectrum of garden plants is influenced by central and north-western European horticultural customs, which were to a great extent shaped by Roman occupation

Evolutionary transition towards permanent chloroplasts? - Division of kleptochloroplasts in starved cells of two species of <i>Dinophysis</i> (Dinophyceae).

Species within the marine toxic dinoflagellate genus Dinophysis are phagotrophic organisms that exploit chloroplasts (kleptochloroplasts) from other protists to perform photosynthesis. Dinophysis spp. acquire the kleptochloroplasts from the ciliate Mesodinium rubrum, which in turn acquires the chloroplasts from a unique clade of cryptophytes. Dinophysis spp. digest the prey nuclei and all other cell organelles upon ingestion (except the kleptochloroplasts) and they are therefore believed to constantly acquire new chloroplasts as the populations grow. Previous studies have, however, indicated that Dinophysis can keep the kleptochloroplasts active during long term starvation and are able to produce photosynthetic pigments when exposed to prey starvation. This indicates a considerable control over the kleptochloroplasts and the ability of Dinophysis to replicate its kleptochloroplasts was therefore re-investigated in detail in this study. The kleptochloroplasts of Dinophysis acuta and Dinophysis acuminata were analyzed using confocal microscopy and 3D bioimaging software during long term starvation experiments. The cell concentrations were monitored to confirm cell divisions and samples were withdrawn each time a doubling had occurred. The results show direct evidence of kleptochloroplastidic division and that the decreases in total kleptochloroplast volume, number of kleptochloroplasts and number of kleptochloroplast centers were not caused by dilution due to cell divisions. This is the first report of division of kleptochloroplasts in any protist without the associated prey nuclei. This indicates that Dinophysis spp. may be in a transitional phase towards possessing permanent chloroplasts, which thereby potentially makes it a key organism to understand the evolution of phototrophic protists

Vocalic Intrusions in Consonant Clusters in Child-Directed vs. Adult-Directed Speech.

In this paper, we investigate a prosodic-phonetic feature in child-directed speech within a dynamic, complex, interactive theoretical framework. We focus on vocalic intrusions, commonly occurring in Norwegian word initial consonant clusters. We analysed child-directed speech from nine Norwegian-speaking mothers to their children, aged 2;6, 4, and 6 years, and compared the incidence and duration of vocalic intrusions in initial consonant clusters in these data with those in adult-directed speech and child speech. When viewed overall, vocalic intrusion was found to be similar in incidence in child- and adult-directed speech. However, closer examination revealed differential behaviour in child-directed speech for certain conditions. Firstly, a difference emerged for one particular phonetic context: While vocalic intrusions in /Cr/ clusters are frequent in adult-directed speech, their presence is near-categorical in child-directed speech. Secondly, we found that the duration of vocalic intrusions was longer in child- than in adult-directed speech, but only when directed to 2;6-year-olds. We argue that vocalic intrusions in child-directed speech may have both a bonding as well as a didactic function, and that these may vary according to the age of the child being addressed

Does vitamin C deficiency affect cognitive development and function?

Vitamin C is a pivotal antioxidant in the brain and has been reported to have numerous functions, including reactive oxygen species scavenging, neuromodulation, and involvement in angiogenesis. Absence of vitamin C in the brain has been shown to be detrimental to survival in newborn SVCT2(−/−) mice and perinatal deficiency have shown to reduce hippocampal volume and neuron number and cause decreased spatial cognition in guinea pigs, suggesting that maternal vitamin C deficiency could have severe consequences for the offspring. Furthermore, vitamin C deficiency has been proposed to play a role in age-related cognitive decline and in stroke risk and severity. The present review discusses the available literature on effects of vitamin C deficiency on the developing and aging brain with particular focus on in vivo experimentation and clinical studies