Going beyond defining: Preschool educators\u27 use of knowledge in their pedagogical reasoning about vocabulary instruction

Previous research investigating both the knowledge of early childhood educators and the support for vocabulary development present in early childhood settings has indicated that both educator knowledge and enacted practice are less than optimal, which has grave implications for children\u27s early vocabulary learning and later reading achievement. Further, the nature of the relationship between educators\u27 knowledge and practice is unclear, making it difficult to discern the best path towards improved knowledge, practice, and children\u27s vocabulary outcomes. The purpose of the present study was to add to the existing literature by using stimulated recall interviews and a grounded approach to examine how 10 preschool educators used their knowledge to made decisions about their moment-to-moment instruction in support of children\u27s vocabulary development. Results indicate that educators were thinking in highly context-specific ways about their goals and strategies for supporting vocabulary learning, taking into account important knowledge of their instructional history with children and of the children themselves to inform their decision making in the moment. In addition, they reported thinking about research-based goals and strategies for supporting vocabulary learning that went beyond simply defining words for children. Implications for research and professional development are discussed

NGC 7582: The Prototype Narrow-Line X-ray Galaxy

NGC 7582 is a candidate prototype of the Narrow Line X-ray Galaxies (NLXGs) found in deep X-ray surveys. An ASCA observation shows the hard (> 3 keV) X-ray continuum of NGC 7582 drops 40% in ~6 ks, implying an AGN, while the soft band (< 3 keV) does not drop in concert with the hard continuum, requiring a separate component. The X-ray spectrum of NGC 7582 also shows a clear 0.5-2 keV soft (kT = 0.8 (+0.9,-0.3) keV or Gamma = 2.4 +/- 0.6; L(X) = 6 x 10**40 ergs s**-1) low--energy component, in addition to a heavily absorbed [N(H) = (6 +/- 2)\times 10**22 cm**-2 ] and variable 2-10 keV power law [Gamma = 0.7 (+0.3,-0.4); L(X) = (1.7-2.3) x 10**42 ergs s**-1]. This is one of the flattest 2-10 keV slopes in any AGN observed with ASCA. (The ROSAT HRI image of NGC 7582 further suggests extent to the SE.) These observations make it clear that the hard X-ray emission of NGC 7582, the most "narrow-line" of the NLXGs, is associated with an AGN. The strong suggestion is that all NLXGs are obscured AGNs, as hypothesized to explain the X-ray background spectral paradox. The separate soft X-ray component makes NGC 7582 (and by extension other NLXGs) detectable as a ROSAT source.Comment: text: Latex2e 10 pages, including 1 table, and 2 postscript figures via psfi

Research on stress and smoking: progress and problems

Despite evidence that smoking behaviour increases in the context of stress, there has yet to be a clear-cut demonstration that nicotine intake is similarly enhanced. Although nicotine intake has been shown to reduce reported anxiety in the context of stress, the controlling conditions (type of stressor, intensity, temporal relationships, etc.) need further exploration. Recent findings involving nicotine's effects on the hypophyseal-adrenal axis provide a new perspective on these issues, in that increased nicotine intake during exposure to a stressor may represent, at least in part, behavioral compensation for diminished sensitivity to nicotine brought about by nicotine-stimulated corticosteroid release. Corticosteroids may decrease central nervous system excitability in a way that could account for anxiety reduction; on the other hand, anxiety reduction may be an epiphenomenon with respect to the reinforcement of smoking behaviour. The integration of behavioural, physiological, and biochemical research exemplified by the above approach should lead to a better understanding of stress and smoking.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73317/1/j.1360-0443.1991.tb01815.x.pd

Unravelling the nature of HD 81032 - a new RS CVn Binary

BVR photometric and quasi-simultaneous optical spectroscopic observations of the star HD 81032 have been carried out during the years 2000 - 2004. A photometric period of $18.802 \pm 0.07$ d has been detected for this star. A large group of spots with a migration period of $7.43 \pm 0.07$ years is inferred from the first three years of the data. H$\alpha$ and Ca II H and K emissions from the star indicate high chromospheric activity. The available photometry in the BVRIJHK bands is consistent with spectral type of K0 IV previously found for this star. We have also examined the spectral energy distribution of HD 81032 for the presence of an infrared colour excess using the 2MASS JHK and IRAS photometry, but found no significant excess in any band abovethe normal values expected for a star with this spectral type. We have also analyzed the X-ray emission properties of this star using data obtained by the ROSAT X-ray observatory during its All-Sky Survey phase. An X-ray flare of about 12 hours duration was detected during the two days of X-ray coverage obtained for this star. Its X-ray spectrum, while only containing 345 counts, is inconsistent with a single-temperature component solar-abundance coronal plasma model, but implies either the presence of two or more plasma components, non-solar abundances, or a combination of both of these properties. All of the above properties of HD 81032 suggest that it is a newly identified, evolved RS CVn binary.Comment: 18 pages, 10 figures, 3 tables, Accepted for the publication in JAp

Usage of Light Emitting Diodes (LEDs) for improved satellite tracking

With the increasing number of satellite launches, especially in Low Earth Orbit (LEO), optical tracking can offer a convenient enhancement of tracking precision and availability. Spaceborne active illumination devices, such as LED payloads, can offer a significant improvement to optical observations, extending the observability interval to the whole eclipse time and performing optimized flash sequences for identification, orbit determination, attitude reconstruction or low data rate communication. The main features of LED panels for optical tracking mounted on small satellites platforms (and with particular regards to nano-satellite platforms) are outlined in this paper, along with the description of the design drivers. The analysis of the performance is referred to Sun-Synchronous (at 700 km of altitude) and International Space Station (400 km) orbits, while the ground segment and the optical link budget reference design relies on a standard university space debris observation station architecture. The paper also outlines the advantages of using different observation techniques and the variety of flashing patterns. The LEDSAT 1U CubeSat, aiming at demonstrating the effectiveness of an LED-based payload for observation and tracking, is used as a study case for examples of the LED payloads and related operations that are reported and described in this paper

An Intense Gamma-Ray Flare of PKS1622-297

We report the observation by the Compton Gamma Ray Observatory of a spectacular flare of radio source PKS 1622-297. A peak flux of 17E-6 cm^-2 s^-1 (E > 100 MeV) was observed. The corresponding isotropic luminosity is 2.9E49 erg/s. We find that PKS 1622-297 exhibits gamma-ray intra-day variability. A flux increase by a factor of at least 3.6 was observed to occur in less than 7.1 hours (with 99% confidence). Assuming an exponential rise, the corresponding doubling time is less than 3.8 hours. A significant flux decrease by a factor of ~2 in 9.7 hours was also observed. Without beaming, the rapid flux change and large isotropic luminosity are inconsistent with the Elliot-Shapiro condition (assuming that gas accretion is the immediate source of power for the gamma-rays). This inconsistency suggests that the gamma-ray emission is beamed. A minimum Doppler factor of 8.1 is implied by the observed lack of pair-production opacity (assuming x-rays are emitted co-spatially with the gamma-rays). Simultaneous observation by EGRET and OSSE finds a spectrum adequately fit by a power law with photon index of -1.9. Although the significance is not sufficient to establish this beyond doubt, the high-energy gamma-ray spectrum appears to evolve from hard to soft as a flare progresses.Comment: 14 pages, 4 figures, 1 tabl

Redundancy in task assignments and group performance

The problem of combining abilities of group members to maximize the performance of the group as a whole is examined in terms of redundancy in task assignments. In particular, ways of distributing a given number of items of information among a given number of individuals to obtain the maximum probability of each item being recalled by at least one individual are studied. It is shown that there exists an optimal distribution scheme which is independent of the amount of material originally given, the size of the group, and individual differences in ability.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45703/1/11336_2005_Article_BF02289817.pd

The Identification of EGRET Sources with Flat-Spectrum Radio Sources

We present a method to assess the reliability of the identification of EGRET sources with extragalactic radio sources. We verify that EGRET is detecting the blazar class of AGN. However, many published identifications are found to be questionable. We provide a table of 42 blazars which we expect to be robust identifications of EGRET sources. This includes one previously unidentified EGRET source, the lensed AGN PKS 1830-210 near the direction of the Galactic center. We provide the best available positions for 16 more radio sources which are also potential identifications for previously unidentified EGRET sources. All high Galactic latitude EGRET sources (b>3 degrees) which demonstrate significant variability can be identified with flat spectrum radio sources. This suggests that EGRET is not detecting any type of AGN other than blazars. This identification method has been used to establish with 99.998% confidence that the peak gamma-ray flux of a blazar is correlated with its average 5 GHz radio flux. An even better correlation is seen between gamma-ray flux and the 2.29 GHz flux density measured with VLBI at the base of the radio jet. Also, using high confidence identifications, we find that the radio sources identified with EGRET sources have larger correlated VLBI flux densities than the parent population of flat radio spectrum sources.Comment: To be published in Ap J, May 20, 1997 issue, Vol. 481. The complete paper is available at http://bu-ast.bu.edu/~mattox/src_id.htm

Biobehavioral research on nicotine use in women

More American women are taking up smoking than men and fewer are quitting; if current trends continue, rates for women will surpass those for men by the mid-1990's. But ironically, much of what is known about the biobehavioural aspects of smoking is based on research using male subjects. The present paper reviews evidence suggesting that: (1) women may differ from men with regard to nicotine intake and/or effects; (2) nicotine intake and effects may be influenced by menstrual cycle phase; (3) oral contraceptive use and estrogen replacement therapy may affect intake and effects of nicotine; (4) the effects of chronic nicotine use on female reproductive endocrinology may have implications for the reinforcement of smoking; and (5) pharmacological agents used to treat smoking may have different effects in women than in men. Guidelines and suggestions are presented by future biobehavioural research in women, including standardization of assessment procedures, attention to the use of appropriate controls, and use of pharmacological probes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73978/1/j.1360-0443.1991.tb01802.x.pd