The subventricular zone (SVZ) is a major site of neurogenesis in the adult. We now show that ependymal and proliferating cells in the adult mouse SVZ express diacylglycerol lipases (DAGLs), enzymes ...that synthesise a CB1/CB2 cannabinoid receptor ligand. DAGL and CB2 antagonists inhibit the proliferation of cultured neural stem cells, and the proliferation of progenitor cells in young animals. Furthermore, CB2 agonists stimulate progenitor cell proliferation in vivo, with this effect being more pronounced in older animals. A similar response was seen with a fatty acid amide hydrolase (FAAH) inhibitor that limits degradation of endocannabinoids. The effects on proliferation were mirrored in changes in the number of neuroblasts migrating from the SVZ to the olfactory bulb (OB). In this context, CB2 antagonists reduced the number of newborn neurons appearing in the OB in the young adult animals while CB2 agonists stimulated this in older animals. These data identify CB2 receptor agonists and FAAH inhibitors as agents that can counteract the naturally observed decline in adult neurogenesis that is associated with ageing.
The preliminary evaluation of stable carbon-isotope ratio mass spectrometry (IRMS) as a novel, alternative method for screening residual heavy or weathered petroleum wastes is presented. Seven ...well-characterised middle-to high-boiling range oils (predominant boiling range: 150–600°C) and their isolated class fractions were analysed by IRMS. Whole oil
δ
13
C values (which express the ratio of
13C to
12C within each sample) showed a small but significant decrease with decreasing oil asphaltene content, from −26.8% for heavier oils to −28.8% for lighter, predominantly paraffinic oils. In agreement with the conventionally observed trend,
δ
13
C values of isolated class fractions were found to increase in the following order:
δ
13
C
sat
(≈
δ
13
C
oil
) <
δ
13
C
aro
<
δ
13
C
pol
<
δ
13
C
asp
,
with
δ
13
C
sat
up to 2.5% more negative than
δ
13
C
pol
and
δ
13
C
asp
. However, this variation was much less pronounced for the heavier oil samples. As a result, isotope type curves exhibited a clear distinction between heavier oils, which produced much flatter type curves, and lighter oils, for which type curves were characteristically sloping. From these preliminary results, IRMS would appear to have application as a potential method for identifying a predominance of asphaltene class fractions in residual hydrocarbon wastes and for distinguishing between heavy and light oily contaminants.
Motion capture data and techniques for blending, editing, and sequencing that data can produce rich, realistic character animation; however, the output of these motion processing techniques sometimes ...appears unnatural. For example, the motion may violate physical laws or reflect unreasonable forces from the character or the environment. While problems such as these can be fixed, doing so is not yet feasible in real time environments. We are interested in developing ways to estimate perceived error in animated human motion so that the output quality of motion processing techniques can be better controlled to meet user goals.This paper presents results of a study of user sensitivity to errors in animated human motion. Errors were systematically added to human jumping motion, and the ability of subjects to detect these errors was measured. We found that users were able to detect motion with errors, and noted some interesting trends: errors in horizontal velocity were easier to detect than errors in vertical velocity, and added accelerations were easier to detect than added decelerations. On the basis of our results, we propose a perceptually based metric for measuring errors in ballistic human motion.
The influence of feeding constraints on the feeding behaviour of Diaea sp. indet., was investigated. Diaea is a crab spider which ambushes its prey and practises extra-intestinal digestion. A ...laboratory study was carried out using fruit flies, Drosophila immigrans, as prey. Diaea feeds from two sites on the prey -- initially the head, followed by the posterior abdomen, with most of the prey's contents being extracted from the head. If additional prey are available, Diaea will, instead of switching to the posterior abdomen, catch a new prey item. The efficiency with which Diaea can extract food is influenced by changes which occur in the prey as a consequence of it being killed and fed on. Evaporative fluid loss from prey is an important constraint on food uptake because it influences the viscosity of the prey's contents. Regardless of whether a new prey item arrives, Diaea discards the prey item on which it is feeding before all of the available food has been extracted from it. The fluid content of the prey is not only part of the food the spider extracts, it is also a resource enabling efficient transfer of food from prey to predator. The value of the prey's fluid content as a resource decreases as a function of feeding time and as a consequence of the spider feeding on the prey.
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