Thermal infrared and optical observations of near-Earth asteroids.

Increased physical characterisation of Near-Earth Asteroids (NEAs) is important for understanding their origin and evolution, the links between meteorites and their parent bodies, and for assessing the impact hazard. NEAs are also representative of small main belt asteroids. Optical observations of 13 NEAs taken at the Jacobus Kapteyn Telescope in 2001 and 2002 are presented, from which composite lightcurves, mean magnitudes, absolute visual magnitudes, rotation periods and lightcurve amplitudes are derived. Thermal infrared photometry and spectrophotometry of 10 NEAs taken at the United Kingdom Infrared Telescope (UKIRT) in March and September 2002 are presented. The Standard Thermal Model (STM), Fast Rotating Model (FRM) and Near-Earth Asteroid Thermal Model (NEATM) have been fitted to the measured fluxes to derive geometric albedos (pv), effective diameters (Deff) and beaming parameters (rj). The NEATM assumes zero thermal emission on the night side of an asteroid, affecting the best-fit rj, overestimating Deff and underestimating pv at large phase angles. The Night Emission Simulated Thermal Model (NESTM) is introduced. NESTM models the night side temperature (Tnight) as an iso-latitudinal fraction if) of the maximum day side 1/4temperature (Tmax calculated for NEATM with rj = 1): Tnight = fTmax cos (f), where (j) is the latitude. A range of / is found for different thermal parameters, which depend on the surface thermal inertia (T). NESTM is tested on thermal IR fluxes generated from simulated asteroid surfaces with different T. NESTM, NEATM and radar diameters are compared and it is found that NESTM removes a systematic bias of NEATM that overestimates asteroid diameters. From these tests, it is suggested that a version of the NESTM which assumes T = 200 J m-2 s-1/2 K-1 (f~ 0.6) is adopted as a default model when the solar phase angle is greater than 45°

Growth, survival, and vulnerability to predation of stocked walleye (Stizostedion vitreum) fingerlings

In laboratory tanks, largemouth bass (Micropterus salmoides) and northern pike (Esox Lucius consumed fathead minnows (Pimephales promelas) 2.6 times more frequently than walleye (Stizostedion vitreum) and 5.7 times more than lepomids. Prey were more vulnerable in circular than rectangular tanks. In field studies, walleye fingerlings averaging 35 mm and 53 mm (mean total length) were stocked in two ponds (3- and 7- hectares) respectively: both contained largemouth bass, northern pike, yellow perch (Perca flavescenes), green sunfish (Lepomis cyanellus), and fathead minnows. Aquatic insects dominated the diet of largemouth bass for 3 days after walleye were stocked, indicating that walleye fingerlings were not especially vulnerable to predation while adjusting to the new environment. Growth and survival were compared between a northeastern glacial lake stock and two Missouri River stocks of walleyes in ponds (0.81-5.7 hectares) with and without predators in 1986 and 1987. Growth of fry differed significantly (P\u3c0.05) between stocks in hatchery ponds, but the difference was probably due to hatching dates and cultural practices rather than genotype. More Missouri River fry survived in 1986, whearas more glacial lake fry survived in 1987. Walleye fingerlings were significantly larger (P\u3c0.05) 301 days later. The slow growth of the glacial lake stock may have been caused by a high incidence of abnormal fin development

Cognitive dysfunction and dementia in Parkinson's disease

Parkinson's disease (PD) is a slowly progressive neurodegenerative disorder mainly characterized by degeneration of dopaminergic neurons in the substantia nigra and the ventral tegmental area, in combination with a varying loss of central noradrenergic (locus coeruleus), cholinergic (nucleus basalis of Meynert) and serotonergic (dorsal raphe nuclei) integrity, leading to a multitude of motor and non-motor behavioral disturbances. Apart from the clinical motor hallmarks, in the early stages of disease, subtle cognitive dysfunction might be seen comprising mainly executive dysfunction, with secondary visuospatial and mnemonic disturbances. In about 20-40% of patients, these problems may eventually proceed to dementia, which constitutes an important risk factor for caregiver distress, decreased quality of life and nursing home placement. Dementia in PD is typically characterized by a progressive dysexecutive syndrome with attentional deficits and fluctuating cognition, often accompanied by psychotic symptoms. It is thought to be the result of a combination of both subcortical and cortical changes. PD-related dopaminergic deficiency in the nucleus caudatus and mesocortical areas (due to degeneration of projections from the substantia nigra and ventral tegmental area) and cholinergic deficiency in the cortex (due to degeneration of ascending projections from the nucleus basalis of Meynert), combined with additional Alzheimer-pathology and cortical Lewy bodies, may greatly contribute to dementia. Current treatment of dementia in PD is based on compensation of the profound cholinergic deficiency. Recent studies with the cholinesterase inhibitors galantamine, donepezil and rivastigmine show promising results in improving cognition and ameliorating psychotic symptoms, which must further be confirmed in randomized controlled trials

Learning Dialogue Strategies from Older and Younger Simulated Users

Older adults are a challenging user group because their behaviour can be highly variable. To the best of our knowledge, this is the first study where dialogue strategies are learned and evaluated with both simulated younger users and simulated older users. The simulated users were derived from a corpus of interactions with a strict system-initiative spoken dialogue system (SDS). Learning from simulated younger users leads to a policy which is close to one of the dialogue strategies of the underlying SDS, while the simulated older users allow us to learn more flexible dialogue strategies that accommodate mixed initiative. We conclude that simulated users are a useful technique for modelling the behaviour of new user groups

How does Acute Naturalistic Stress Affect Memory and Learning in Dutch Marines?

The Royal Marines represent a high-reliability occupation, where stress levels are often intense and mistakes can be costly. Maintaining effective performance under these stressful conditions is an intimidating challenge, therefore it is crucial to provide these professionals with sound research results which can improve the insight into the relationship between acute stress and optimal cognitive performance

Entanglement of two individual atoms using the Rydberg blockade

We report on our recent progress on the manipulation of single rubidium atoms trapped in optical tweezers and the generation of entanglement between two atoms, each individually trapped in neighboring tweezers. To create an entangled state of two atoms in their ground states, we make use of the Rydberg blockade mechanism. The degree of entanglement is measured using global rotations of the internal states of both atoms. Such internal state rotations on a single atom are demonstrated with a high fidelity.Comment: Proceeding of the 19th International Conference on Laser Spectroscopy ICOLS 2009, 7-13 June 2009, Hokkaido, Japa