Does Time Really Slow Down during a Frightening Event?

Observers commonly report that time seems to have moved in slow motion during a life-threatening event. It is unknown whether this is a function of increased time resolution during the event, or instead an illusion of remembering an emotionally salient event. Using a hand-held device to measure speed of visual perception, participants experienced free fall for 31 m before landing safely in a net. We found no evidence of increased temporal resolution, in apparent conflict with the fact that participants retrospectively estimated their own fall to last 36% longer than others' falls. The duration dilation during a frightening event, and the lack of concomitant increase in temporal resolution, indicate that subjective time is not a single entity that speeds or slows, but instead is composed of separable subcomponents. Our findings suggest that time-slowing is a function of recollection, not perception: 1a richer encoding of memory may cause a salient event to appear, retrospectively, as though it lasted longer

Morphologic alterations in the rat medullary collecting duct following potassium depletion

Morphologic alterations in the rat medullary collecting duct following potassium depletion. Freeze-fracture and thin-section electron microscopy and morphometry were used to characterize further the response of the rat medullary collecting duct to potassium depletion. In freeze-fracture replicas, principal cells and intercalated cells were identified based on the assumption that intercalated cells possess a high density of rod-shaped intra-membrane particles in their luminal membranes. Potassium depletion caused an increase in the relative number of cells with a high density of rod-shaped particles from the control level of 22% to 31% after 2 weeks and to 36% after 4 weeks. The frequency of intercalated cells identified by thin-section criteria was, however, about 35% in controls and unchanged by potassium depletion. This suggests that intercalated cells can have two types of membrane morphology. In potassium depletion, all intercalated cells display a high density of rod-shaped particles in their luminal membranes. In addition, the luminal membrane area of intercalated cells increased more than threefold, and the density of their rod-shaped particles increased by 21%. These observations suggest that the intercalated cell and its rod-shaped particle may be involved with the potassium reabsorption that occurs in this nephron segment with potassium depletion.Modifications morphologiques du canal collecteur du rat consécutives à une depletion en potassium. Le cryo-décapage, la microscopie électronique sur coupes fines et la morphométrie ont été utilisés pour mieux établir la réponse du canal collecteur médullaire du rat à la depletion en potassium. Sur les répliques de cryo-décapage les cellules principales et les cellules intercalaires ont été identifiées à partir de l'hypothèse selon laquelle les cellules intercalaires possèdent une grande densité de particules intra-membranaires luminales en forme de batonnets. La depletion en potassium a déterminé une augmentation du nombre relatif de cellules de ce type de 22% chez les témoins à 33% après 2 semaines et 36% après 4 semaines. La fréquence des cellules intercalaires identifiées sur coupes minces, cependant, était de 35% chez les contrôles et non modifiés par la depletion en potassium. Cela suggère que les cellules intercalaires peuvent avoir deux types de morphologies membranaires. Dans la depletion en potassium toutes les cellules intercalaires ont une grande densité de particules en forme de batonnets dans leurs membranes luminales. De plus, la surface membranaire luminale des cellules intercalaires augmente de plus de trois fois et la densité des particules augmente de 21%. Ces observations suggèrent que les cellules intercalaires et leurs particules en forme de batonnets peuvent être impliquées dans la réabsorption de potassium qui prend place dans ce segment du néphron au cours de la déplétion en potassium

The Effect of Preschool Experiences on the Achievement of Kindergarten Children Enrolled in the 1971-1972 Follow Through Program in Waterloo, Iowa

The problem of the investigation concerned itself with the effect of preschool experiences on the achievement of the kindergarten children enrolled in the 1971-1972 Follow Through Program in Waterloo, Iowa, which used the Pittsburgh, Pennsylvania, model of individually prescribed instruction. The study explored the effects of preschool experience upon kindergarten males and females as contrasted to the male and female kindergarten children without preschool experience. Two conceptual constructs gave direction and provided the rationale for this study. The first conceptual construct provided research related to early childhood education presented according to the Geneticist, Environmentalist, and the Interactionalist\u27s positions. The second construct presented research related to preschool learning to show the influences of home atmosphere and preschool attendance. Each of the six curriculum areas of the P.E.P. (Primary Education Project) Early Learning Curriculum, which were Quantification, Classification, Gross Motor, Visual Motor, Auditory Motor, and Letters and Numerals generated two hypotheses to be investigated. Males with preschool experience were contrasted with males without preschool experience. Females with preschool experience were contrasted with females without preschool experience. Statistically, the hypotheses were stated in the null and specified a direction for analysis. It was noted that children with preschool experience should evidence higher levels of achievement than those without preschool experience. The effects of preschool experience was tested with the nonparametric sign test which uses plus and minus signs rather than quantitative measures as its data. The probability associated with the occurrence of a particular number of plus or minus signs was determined by reference to the binomial distribution with P = Q = ½, in Appendix G. The following significance levels of the probabilities were chosen 1.05, Highly significant; .10, Significant; and, .10 to .20, Trend toward significant. The findings showed that generally, preschool experience did make a difference. Preschool experience had a highly significant effect for the males in the curriculum areas of Quantification, Classification, and Auditory Motor. Preschool experience had a highly significant effect for females in Quantification, Classification, Auditory Motor, and Letters and Numerals. A trend toward significant was noted for males and females in the area of Visual Motor. Preschool experience had little or no effect in the curriculum areas of Gross Motor and Letters and Numerals for the males, and Gross Motor for the females. The findings did suggest that preschool programs are desirable in providing a foundation for kindergarten experiences

Autonomous Payload Operations Onboard the International Space Station

Operating the International Space Station (ISS) involves many complex crew tended, ground operated and combined systems. Over the life of the ISS program, it has become evident that by having automated and autonomous systems on board, more can be accomplished and at the same time reduce the workload of the crew and ground operators. Engineers at the National Aeronautics and Space Administration's (NASA) Marshall Space Flight Center in Huntsville Alabama, working in collaboration with The Charles Stark Draper Laboratory have developed an autonomous software system that uses the Timeliner User Interface Language and expert logic to continuously monitor ISS payload systems, issue commands and signal ground operators as required. This paper describes the development history of the system, its concept of operation and components. The paper also discusses the testing process as well as the facilities used to develop the system. The paper concludes with a description of future enhancement plans for use on the ISS as well as potential applications to Lunar and Mars exploration systems

Detection of a transit by the planetary companion of HD 80606

We report the detection of a transit egress by the ~ 3.9-Jupiter-mass planet HD 80606b, an object in a highly-eccentric orbit (e ~ 0.93) about its parent star of approximately solar type. The astrophysical reality of the signal of variability in HD 80606 is confirmed by observation with two independent telescope systems, and checks against several reference stars in the field. Differential photometry with respect to the nearby comparison star HD 80607 provides a precise light curve. Modelling of the light curve with a full eccentric-orbit model indicates a planet/star-radius ratio of 0.1057 +/- 0.0018, corresponding to a planet radius of 1.029 R_J for a solar-radius parent star; and a precise orbital inclination of 89.285 +/- 0.023 degrees, giving a total transit duration of 12.1 +/- 0.4 hours. The planet hence joins HD 17156b in a class of highly eccentric transiting planets, in which HD 80606b has both the longest period and most eccentric orbit. The recently reported discovery of a secondary eclipse of HD 80606b by the Spitzer Space Observatory permits a combined analysis with the mid-time of primary transit in which the orbital parameters of the system can be tightly constrained. We derive a transit ephemeris of T_tr = HJD (2454876.344 +/- 0.011) + (111.4277 +/- 0.0032) E.Comment: Accepted for publication in MNRAS Letter

Stellar photometry with Multi Conjugate Adaptive Optics

We overview the current status of photometric analyses of images collected with Multi Conjugate Adaptive Optics (MCAO) at 8-10m class telescopes that operated, or are operating, on sky. Particular attention will be payed to resolved stellar population studies. Stars in crowded stellar systems, such as globular clusters or in nearby galaxies, are ideal test particles to test AO performance. We will focus the discussion on photometric precision and accuracy reached nowadays. We briefly describe our project on stellar photometry and astrometry of Galactic globular clusters using images taken with GeMS at the Gemini South telescope. We also present the photometry performed with DAOPHOT suite of programs into the crowded regions of these globulars reaching very faint limiting magnitudes Ks ~21.5 mag on moderately large fields of view (~1.5 arcmin squared). We highlight the need for new algorithms to improve the modeling of the complex variation of the Point Spread Function across the field of view. Finally, we outline the role that large samples of stellar standards plays in providing a detailed description of the MCAO performance and in precise and accurate colour{magnitude diagrams.Comment: 17 pages, 12 figures, SPIE 201

The White Dwarf Cooling Sequence of NGC6397

We present the results of a deep Hubble Space Telescope (HST) exposure of the nearby globular cluster NGC6397, focussing attention on the cluster's white dwarf cooling sequence. This sequence is shown to extend over 5 magnitudes in depth, with an apparent cutoff at magnitude F814W=27.6. We demonstrate, using both artificial star tests and the detectability of background galaxies at fainter magnitudes, that the cutoff is real and represents the truncation of the white dwarf luminosity function in this cluster. We perform a detailed comparison between cooling models and the observed distribution of white dwarfs in colour and magnitude, taking into account uncertainties in distance, extinction, white dwarf mass, progenitor lifetimes, binarity and cooling model uncertainties. After marginalising over these variables, we obtain values for the cluster distance modulus and age of \mu_0 = 12.02 \pm 0.06 and T_c = 11.47 \pm 0.47Gyr (95% confidence limits). Our inferred distance and white dwarf initial-final mass relations are in good agreement with other independent determinations, and the cluster age is consistent with, but more precise than, prior determinations made using the main sequence turnoff method. In particular, within the context of the currently accepted \Lambda CDM cosmological model, this age places the formation of NGC6397 at a redshift z=3, at a time when the cosmological star formation rate was approaching its peak.Comment: 56 pages, 30 figure