8,397 research outputs found
THE EFFECTIVENESS OF EDU-GAMES SOFTWARE (CD-ROM) AS MEDIA IN THE ENGLISH TEACHING-LEARNING PROCESS TO IMPROVE VOCABULARY MASTERY OF THE FIFTH GRADE STUDENTS OF SD KANISIUS WONOSARI II
The objective of this research is to know whether or not there is a
significant difference in the vocabulary mastery between the students who are
taught by using Edu-Games Software (CD-ROM) and those who are not taught by
using Edu-Games Software (CD-ROM).
This research is quasi-experimental research in which the choice of the
research sample was done randomly. The sample of this research consisted of 35
students (two classes). The two classes were class 5 A as the experimental group
and 5 B as the control group. The data were collected by using a vocabulary test.
The two groups were given pre-test (before the experiment was conducted) and
the post-test (after the experiment). During the research, the students of 5 A or the
experimental group were taught vocabulary by using Edu-Games Software (CDROM)
as media in the English teaching and learning process, while the control
group were not taught by using Edu-Games Software (CD-ROM). From the tryout,
it was found out that 37 items of the vocabulary mastery test were valid with
the reliability of 0.897. The data were collected by means of a descriptive and an
inferential statistics technique. The test of normality and homogeneity were
conducted before the test of hypothesis was applied.
The data show that the vocabulary mastery of students who were taught
using Edu-Games Software (CD-ROM) is in the very high category. The mean of
the gain scores of the experimental group is 5.67, while the mean of the control
group is only 1.29. Moreover, it was found that there is a significant difference in
the scores of students’ vocabulary mastery (to =3.654; p=0.000) between those
who were taught using Edu-Games Software (CD-ROM) and those who were not.
It can be concluded that the use of Edu-Games Software (CD-ROM) is good to
teach vocabulary for it can increase the vocabulary mastery of the fifth grade
students of SD Kanisius Wonosari II
Lepton flavour violating slepton decays to test type-I and II seesaw at the LHC
Searches at the LHC of lepton flavour violation (LFV) in slepton decays can
indirectly test both type-I and II seesaw mechanisms. Assuming universal
flavour-blind boundary conditions, LFV in the neutrino sector is related to LFV
in the slepton sector by means of the renormalization group equations. Ratios
of LFV slepton decay rates result to be a very effective way to extract the
imprint left by the neutrino sector. Some neutrino scenarios within the type-I
seesaw mechanism are studied. Moreover, for both type-I and II seesaw
mechanisms, a scan over the minimal supergravity parameter space is performed
to estimate how large LFV slepton decay rates can be, while respecting current
low-energy constraints.Comment: 4 pages; to appear in the proceedings of the 17th International
Conference on Supersymmetry and the Unification of Fundamental Interactions
(SUSY09), Boston (MA), USA, 5-10 Jun 200
The anticenter old open cluster NGC 1883: radial velocity and metallicity
Having already reported on the first photometric study of the
intermediate-age open cluster NGC 1883 (Carraro et al. 2003), we present in
this paper the first spectroscopic multi-epoch investigation of a sample of
evolved stars in the same cluster. The aim is to derive the cluster membership,
velocity and metallicity, and discuss recent claims in the literature (Tadross
2005) that NGC 1883 is as metal poor as globular clusters in the Halo. Besides,
being one of the few outer Galactic disk intermediate-age open clusters known
so far, it is an ideal target to improve our knowledge of the Galactic disk
radial abundance gradient, that is a basic ingredient for any chemical
evolution model of the Milky Way. The new data we obtained allow us to put NGC
1883's basic parameters more reliable. We find that the cluster has a mean
metallicity of [Fe/H] = -0.200.22, from which we infer an age
(650 Myr) close to the Hyades one and a Galactocentric distance
of 12.3 kpc. The metal abundance, kinematics, and position make
NGC 1883 a genuine outer disk intermediate-age open cluster. We confirm that in
the outer Galactic disk the abundance gradient is shallower than in the solar
vicinity.Comment: 8 pages, 7 eps figures (some degraded in resolution), accepted for
publication in MNRA
Abundance analysis of red clump stars in the old, inner disc, open cluster NGC 4337: a twin of NGC 752?
Open star clusters older than ~ 1 Gyr are rare in the inner Galactic disc.
Still, they are objects that hold crucial information for probing the chemical
evolution of these regions of the Milky Way. We aim at increasing the number of
old open clusters in the inner disc for which high-resolution metal abundances
are available. Here we report on NGC 4337, which was recently discovered to be
an old, inner disc open cluster. We present the very first high-resolution
spectroscopy of seven clump stars that are all cluster members. We performed a
detailed abundance analysis for them. We find that NGC 4337 is marginally more
metal-rich than the Sun, with [Fe/H]=+0.120.05. The abundance ratios of
-elements are generally solar. At odds with recent studies on
intermediate-age and old open clusters in the Galactic disc, Ba is
under-abundant in NGC 4337 compared with the Sun. Our analysis of the iron-peak
elements (Cr and Ni) does not reveal anything anomalous. Based on these
results, we estimate the cluster age to be 1.6 Gyr, and derive
a reddening E(B-V)=0.230.05, and an apparent distance modulus
. Its distance to the Galactic centre is 7.6 kpc. With
this distance and metallicity, NGC 4337 fits the metallicity gradient for the
inner Galactic disc fairly well. The age and metallicity we measured make NGC
4337 a twin of the well-known old open cluster NGC 752. The red clumps of these
two clusters bear an amazing resemblance. But the main sequence of NGC 752 is
significantly more depleted in stars than that of NGC 4337. This would mean
that NGC 752 is in a much more advanced dynamical stage, being on the verge of
dissolving into the general Galactic field. Our results make NGC 4337 an
extremely interesting object for further studies of stellar evolution in the
critical turn-off mass range 1.1-1.4 solar masses.Comment: 7 pages, 8 eps figures, in press in Astronomy and Astrophysics. arXiv
admin note: text overlap with arXiv:1401.156
NGC 1883: a neglected intermediate-age open cluster located in the outskirts of the Galactic disk
We report on CCD photometry of a field centered in the region of the
open cluster NGC 1883 down to V=21. This cluster has never been studied
insofar, and we provide for the first time estimates of its fundamental
parameters, namely radial extent, age, distance and reddening. We find that the
cluster has a radius of about 2.5 arcmin, and shows signatures of dynamical
relaxation. NGC 1883 is located in the anti-center direction, and exhibits a
reddening in the range E, depending on the metal abundance.
It turns out to be of intermediate-age (1 billion years old), and quite distant
for an open cluster. In fact it is located 4.8 kpc from the Sun, and more than
13 kpc from the Galactic center. This results makes NGC 1883 one of the most
peripheral old open clusters, with important consequences for the trend of the
metallicity with distance in the outer Galactic disk.Comment: 5 pages, 6 eps figures, in press in MNRA
Radial velocities and metallicities of red giant stars in the old open cluster NGC 7762
We present and discuss radial velocity and the very first metallicity
measurements for nine evolved stars in the poorly known old open cluster NGC
7762. We isolated eight radial velocity cluster members and one interloper.
Radial velocities are in good agreement with previous studies. NGC 7762 turns
out to be of solar metallicity within the uncertainties ([Fe/H]=0.040.12).
For this metallicity, the cluster age is 2.50.2 Gyr, and falls in a age
range where only a few old open clusters are known. With respect to previous
studies, we find a larger distance, implying the cluster to be located at
900 pc from the Sun. For most of the elements we measure
solar-scaled abundance ratios. We searched the literature for open clusters of
similar age in the solar vicinity and found that NGC 7762 can be considered a
twin of Ruprecht 147, a similar age cluster located at only 300 pc from the
Sun. In fact, beside age, also metallicity and abundance ratios are very close
to Ruprecht 147 values within the observational uncertainties.Comment: 8 pages, 5 figures, accepted for publication in the Astronomical
Journa
A study of the two northern open clusters NGC 1582 and NGC 1663
We present CCD UBV(I)C observations obtained in the field of the previously unstudied northern open clusters NGC 1582 and NGC 1663. For the former, we also provide high-resolution spectra of the brightest stars and complement our data with Two-Micron All-Sky-Survey (2MASS) near-infrared photometry and with astrometric data from the Tycho-2 catalog. From the analysis of all these data, we argue that NGC 1582 is a very poor, quite large and heavily contaminated open cluster. It turns out to have a reddening EB-V = 0.35 +/- 0.03, to be situated 1100 +/- 100 pc from the Sun and to have an age of 300 +/- 100 Myr. On the other hand, we were not able to unambiguously clarify the nature of NGC 1663. By assuming it is a real cluster and from the analysis of its photometric diagrams, we found a color excess value EB-V = 0.20, an intermediate age value ( ~ 2000 Myr) and a distance of about 700 pc. The distribution of the stars in the region however suggests we are probably facing an open cluster remnant. As an additional result, we obtained aperture photometry of three previously unclassified galaxies placed in the field of NGC 1663 and performed a preliminary morphological classification of them.Fil: Baume, Gustavo Luis. Università di Padova; ItaliaFil: Villanova, S.. Università di Padova; Italia. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata. Instituto de AstrofÃsica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y GeofÃsicas. Instituto de AstrofÃsica la Plata; ArgentinaFil: Carraro, Giovanni. Università di Padova; Itali
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