186 research outputs found

    Species Composition and Diversity of Hawk Populations in Northeastern Arkansas

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    Species composition and diversity of hawk populations were analyzed for northeastern Arkansas by the use of roadside censuses conducted in September through April from 1974- 1977. Data from 10 years of Jonesboro Christmas Bird Counts were also analyzed. During the roadside survey 20,174 miles were driven and 1819 raptors were counted. Ten species were observed with the Red-tailed Hawk being most abundant followed by the Marsh Hawk and the American Kestrel. Eight species were recorded from the 10 years of Christmas Bird Counts. Annual breeding bird surveys and spot records turned up three additional species making a total of 14 species in 15 years of study. Although hawk populations fluctuate from year to year, the data do not reveal any downward trend in numbers in northeastern Arkansas. Large concentrations of hawks do not appear in this region of the state until after mid-September. Populations reach a peak in December after which they decline in January. A second peak is reached in February followed by a gradual decline such that in April the American Kestrel is the only species consistently seen from the roadside. After April only a few hawks remain to nest. Both Krider\u27s and melanistic Red-tails occur here but from a total of 864 Red-tailed Hawks observed only 26 Krider\u27s and 31 melanistic or Buteo iamaicensis harlanii were recorded

    Statewide Mathematics Professional Development: Teacher Knowledge, Self-Efficacy, and Beliefs

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    We examined the impact of a state mandated K-12 mathematics professional development course on knowledge, self-efficacy and beliefs of nearly 4,000 teachers and administrators. Participants completed the Mathematical Thinking for Instruction course, emphasizing student thinking, problem-solving, and content knowledge specific to mathematics instruction. Inventories utilizing items fromthe Learning Mathematics for Teaching project (2005) measured changes in participants’ Mathematical Knowledge for Teaching (MKT) and an end-of-course self-evaluation enabled analysis of changes in MKT, self-efficacy and beliefs. Statistically significant changes were found in all three variables. This study adds to our understanding of the potential usefulness of mandating professional development as a policy vehicle for influencing educators’ mathematics knowledge and beliefs

    Can Teachers Accurately Predict Student Performance?

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    In two studies, we examined the effect of professional development to improve mathematics instruction on the accuracy of teachers\u27 monitoring of student learning. Study 1 was conducted with 36 teachers participating in three years of professional development. Judgment accuracy was influenced by the fidelity with which what was learned in the professional development. Study 2 was conducted with 64 teachers from 8 schools, which were randomly assigned to receive professional development or serve as a control. Judgment accuracy was greater for teachers receiving professional development than for teachers who did not and teachers were better to predict students\u27 computational skills

    Scientific Opportunities with an X-ray Free-Electron Laser Oscillator

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    An X-ray free-electron laser oscillator (XFELO) is a new type of hard X-ray source that would produce fully coherent pulses with meV bandwidth and stable intensity. The XFELO complements existing sources based on self-amplified spontaneous emission (SASE) from high-gain X-ray free-electron lasers (XFEL) that produce ultra-short pulses with broad-band chaotic spectra. This report is based on discussions of scientific opportunities enabled by an XFELO during a workshop held at SLAC on June 29 - July 1, 2016Comment: 21 pages, 12 figure

    Plated Cambrian Bilaterians Reveal the Earliest Stages of Echinoderm Evolution

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    Echinoderms are unique in being pentaradiate, having diverged from the ancestral bilaterian body plan more radically than any other animal phylum. This transformation arises during ontogeny, as echinoderm larvae are initially bilateral, then pass through an asymmetric phase, before giving rise to the pentaradiate adult. Many fossil echinoderms are radial and a few are asymmetric, but until now none have been described that show the original bilaterian stage in echinoderm evolution. Here we report new fossils from the early middle Cambrian of southern Europe that are the first echinoderms with a fully bilaterian body plan as adults. Morphologically they are intermediate between two of the most basal classes, the Ctenocystoidea and Cincta. This provides a root for all echinoderms and confirms that the earliest members were deposit feeders not suspension feeders

    Internal and external forcing of multidecadal Atlantic climate variability over the past 1,200 years

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    The North Atlantic experiences climate variability on multidecadal scales, which is sometimes referred to as Atlantic multidecadal variability. However, the relative contributions of external forcing such as changes in solar irradiance or volcanic activity and internal dynamics to these variations are unclear. Here we provide evidence for persistent summer Atlantic multidecadal variability from AD 800 to 2010 using a network of annually resolved terrestrial proxy records from the circum-North Atlantic region. We find that large volcanic eruptions and solar irradiance minima induce cool phases of Atlantic multidecadal variability and collectively explain about 30% of the variance in the reconstruction on timescales greater than 30 years. We are then able to isolate the internally generated component of Atlantic multidecadal variability, which we define as the Atlantic multidecadal oscillation. We find that the Atlantic multidecadal oscillation is the largest contributor to Atlantic multidecadal variability over the past 1,200 years. We also identify coherence between the Atlantic multidecadal oscillation and Northern Hemisphere temperature variations, leading us to conclude that the apparent link between Atlantic multidecadal variability and regional to hemispheric climate does not arise solely from a common response to external drivers, and may instead reflect dynamic processes
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