1,425 research outputs found
Analysis of the Swift Gamma-Ray Bursts duration
Two classes of gamma-ray bursts have been identified in the BATSE catalogs
characterized by durations shorter and longer than about 2 seconds. There are,
however, some indications for the existence of a third type of burst. Swift
satellite detectors have different spectral sensitivity than pre-Swift ones for
gamma-ray bursts. Therefore it is worth to reanalyze the durations and their
distribution and also the classification of GRBs. Using The First BAT Catalog
the maximum likelihood estimation was used to analyzed the duration
distribution of GRBs. The three log-normal fit is significantly (99.54 %
probability) better than the two for the duration distribution. Monte-Carlo
simulations also confirm this probability (99.2 %).Comment: NANJING GAMMA-RAY BURST CONFERENCE 200
Repeated Testing Sessions and Scholastic Aptitude in College Students’ Metacognitive Accuracy
We performed three experiments to examine the effects of repeated study–judgement–test sessions on metacognitive monitoring, and to see if better students (those with higher Scholastic Aptitude Test or SAT scores) outperform low SAT students. In all experiments, mean metacognitive accuracy (bias scores and Gamma correlations) did improve with practice. Most improvement involved students’ ability to predict which items would not be recalled later. In addition, students with high SAT scores recalled more items, were less overconfident, and adjusted their predictions more effectively. Thus, high SAT students may be able to adjust their metacognitive monitoring effectively without feedback, but low SAT students appear unlikely to do so. Educators may need to devise more explicit techniques to help low SAT students improve their metacognitive monitoring during the course of a semester
Distribution and Intracellular Localization of Titanium in Plants After Titanium Treatment
The physiological role of titanium in plants has not been elucidated yet, but a higher rate of growth , greater chlorophyll content and higher productivity, among others , may be attributed to this element. We have investigated the distribution of titanium in wheat seedlings after Titavit (a Ti ·ascorbate containing plant conditioner) treatment applied either through the leaf or through the root. In field experiments, we also sprayed spinach plants with Titavit. We have found a practically unidirectional tran slocation of Ti from the shoot into the root, and a preferential local ization of Ti in the nuclear cell fraction as seen by JCP-AES (inductively coupled plasma atomic emission spectrometry). Electron microscopic X·ray microanalysis after chemical fixation showed little or no accumulation of Ti in the cells of the treated organs . However, if there was in appreciable Xray emission at 4.5 keV (Ti), it was recorded from the nucleoplasm and nucleolus. The comparison of ICPAES and X-ray analyses leads us to the conclusion that the majority of Ti may be in a diffusible form in the treated cells, except the nuclei, where Ti may be bound firmly
Overtone and multi-mode RR Lyrae stars in the globular cluster M3
The overtone and multi-mode RR Lyrae stars in the globular cluster M3 are
studied using a 200-d long, and time-series photometry
obtained in 2012. 70\% of the 52 overtone variables observed show some kind of
multi-periodicity (additional frequency at
frequency ratio, Blazhko effect, double/multi-mode pulsation, period doubling).
A signal at 0.587 frequency ratio to the fundamental-mode frequency is detected
in the double-mode star, V13, which may be identified as the second radial
overtone mode. If this mode-identification is correct, than V13 is the first RR
Lyrae star showing triple-mode pulsation of the first three radial modes.
Either the Blazhko effect or the frequency (or both of these
phenomena) appear in 7 double-mode stars. The
period ratio of RRd stars showing the Blazhko effect are anomalous. A
displacement of the main frequency component at the fundamental-mode with the
value of modulation frequency (or its half) is detected in three Blazhko RRd
stars parallel with the appearance of the overtone-mode pulsation. The
frequency appears in RRc stars that lie at the blue side of the
double-mode region and in RRd stars, raising the suspicion that its occurrence
may be connected to double-mode pulsation. The changes of the Blazhko and
double-mode properties of the stars are also reviewed using the recent and
archive photometric data.Comment: accepted for publication in ApJ Suppl. 26 pages, 25 figure
Activity of 50 Long-Period Comets Beyond 5.2 AU
Remote investigations of the ancient solar system matter has been
traditionally carried out through the observations of long-period (LP) comets
that are less affected by solar irradiation than the short-period counterparts
orbiting much closer to the Sun. Here we summarize the results of our
decade-long survey of the distant activity of LP comets. We found that the most
important separation in the dataset is based on the dynamical nature of the
objects. Dynamically new comets are characterized by a higher level of activity
on average: the most active new comets in our sample can be characterized by
afrho values >3--4 higher than that of our most active returning comets. New
comets develop more symmetric comae, suggesting a generally isotropic outflow.
Contrary to this, the coma of recurrent comets can be less symmetrical,
ocassionally exhibiting negative slope parameters, suggesting sudden variations
in matter production. The morphological appearance of the observed comets is
rather diverse. A surprisingly large fraction of the comets have long, teniouos
tails, but the presence of impressive tails does not show a clear correlation
with the brightness of the comets.Comment: 21 pages, 4 figures, accepted for publication in A
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