4,239 research outputs found
Zinc differentially modulates DNA damage induced by anthracyclines in normal and cancer cells
Zinc is one of the most essential trace elements in human organism. Low blood level of zinc is often noted in acute lymphocytic leukemia (ALL). Treatment with zinc adjuvant is hypothesized to accelerate recovery from ALL, and in conjunction with chemotherapy, cure ALL. Aim: We determined the effect of zinc on DNA damage induced by doxorubicin and idarubicin, two anthracyclines used in ALL treatment. Methods: The experiment was performed on acute lymphoblastic leukemia cell line (CCRF-CEM) and lymphocytes from peripheral blood of healthy, adult subjects. To evaluate the level of DNA damage the comet assay in the alkaline version was used. Results: We observed a significant difference in DNA damage level between normal and cancer cells in the presence of zinc. Cancer cells exhibited a significant increase of DNA damage in the presence of zinc, while in lymphocytes no such effect was observed. Conclusion: Our results suggest that zinc may protect normal cells against DNA-damaging action of anthracyclins and increase this action in cancer cells
SkyDOT (Sky Database for Objects in the Time Domain): A Virtual Observatory for Variability Studies at LANL
The mining of Virtual Observatories (VOs) is becoming a powerful new method
for discovery in astronomy. Here we report on the development of SkyDOT (Sky
Database for Objects in the Time domain), a new Virtual Observatory, which is
dedicated to the study of sky variability. The site will confederate a number
of massive variability surveys and enable exploration of the time domain in
astronomy. We discuss the architecture of the database and the functionality of
the user interface. An important aspect of SkyDOT is that it is continuously
updated in near real time so that users can access new observations in a timely
manner. The site will also utilize high level machine learning tools that will
allow sophisticated mining of the archive. Another key feature is the real time
data stream provided by RAPTOR (RAPid Telescopes for Optical Response), a new
sky monitoring experiment under construction at Los Alamos National Laboratory
(LANL).Comment: to appear in SPIE proceedings vol. 4846, 11 pages, 5 figure
Racial Differences in Inequality Aversion: Evidence from Real World Respondents in the Ultimatum Game
The distinct historical and cultural experiences of American blacks and whites may influence whether members of those groups perceive a particular exchange as fair. We investigate racial differences in fairness standards using preferences for equal treatment in the ultimatum game, where responders choose to allow a proposed division of a monetary amount or to block it. Although previous research has studied group differences in the ultimatum game, no study has been able to examine these across races in America. We use a sample of over 1600 blacks and whites drawn from the universe of registered voters in three states and merged with information on neighborhood income and racial composition. We experimentally vary proposed divisions as well as the implied race of the ultimatum game proposer. We find no overall racial differences in acceptance rates or aversion to unequal divisions. However, we uncover racial differences in the response to pecuniary returns conditional on inequality of the division. This is driven by the lowest income group in our sample, which represents the 10th percentile of the black income distribution. The racial differences are robust across gender and age groups. We also find that blacks are more sensitive to unfair proposals from other blacks.
Active learning in optics and photonics: Liquid Crystal Display in the do-it-yourself
Monitors are in the center of media productions and hold an important function as the main visual interface. Tablets and smartphones are becoming more and more important work tools in the media industry. As an extension to our lecture contents an intensive discussion of different display technologies and its applications is taking place now. The established LCD (Liquid Crystal Display) technology and the promising OLED (Organic Light Emitting Diode) technology are in the focus. The classic LCD is currently the most important display technology. The paper will present how the students should develop sense for display technologies besides the theoretical scientific basics. The workshop focuses increasingly on the technical aspects of the display technology and has the goal of deepening the students understanding of the functionality by building simple Liquid Crystal Displays by themselves. The authors will present their experience in the field of display technologies. A mixture of theoretical and practical lectures has the goal of a deeper understanding in the field of digital color representation and display technologies. The design and development of a suitable learning environment with the required infrastructure is crucial. The main focus of this paper is on the hands-on optics workshop “Liquid Crystal Display in the do-it-yourself”
Increased knowledge transfer by using modern high-speed camera
A broad theoretical knowledge in Optics and Photonics is essential for media engineers. A combination of theory in the lectures augmented by practical work during the laboratory experiments forms the foundation of our gradual approach in communicating clearly and intensively all of the required topics. All laboratory experiments are guided but carried out by the students themselves and produced with a modern high-speed camera. This offers possibilities to analyze and iterate very fast phenomena. The slow motion footage makes it easily to analyze, to measure and to calculate certain sequences. This leads to a very intensive discussion regarding the provided topics and the used camera technology, resulting in a high standard knowledge transfer. Physics get now visible and more accessible for students. This paper presents how the students execute and analyze experiments using modern technology. The results are prepared as media-friendly computer animation and video recordings
Nature of nuclear rings in unbarred galaxies: NGC 7742 and NGC 7217
We have studied the unbarred Sb galaxy with a nuclear star-forming ring, NGC
7742, by means of 2D spectroscopy, long-slit spectroscopy, and imaging, and
have compared the results with the properties of another galaxy of this type,
NGC 7217, which is studied by us earlier. Both galaxies have many peculiar
features in common: each has two global exponential stellar disks with
different scalelengths, each possesses a circumnuclear inclined gaseous disk
with a radius of 300 pc, and each has a global counterrotating subsystem,
gaseous one in NGC 7742 and stellar one in NGC 7217. We suggest that past minor
merger is the probable cause of all these peculiarities, including appearance
of the nuclear star-forming rings without global bars; the rings might be
produced as resonance features by tidally induced oval distortions of the
global stellar disks.Comment: Accepted to AJ, 11 PS/EPS figures (5 figures were added in color
Planets in Stellar Clusters Extensive Search. I. Discovery of 47 Low-amplitude Variables in the Metal-rich Cluster NGC 6791 with Millimagnitude Image Subtraction Photometry
We have undertaken a long-term project, Planets in Stellar Clusters Extensive
Search (PISCES), to search for transiting planets in open clusters. As our
first target we have chosen NGC 6791 -- a very old, populous, metal rich
cluster. In this paper we present the results of a test observing run at the
FLWO 1.2 m telescope. Our primary goal is to demonstrate the feasibility of
obtaining the accuracy required for planetary transit detection using image
subtraction photometry on data collected with a 1 m class telescope. We present
a catalog of 62 variable stars, 47 of them newly discovered, most with low
amplitude variability. Among those there are several BY Dra type variables. We
have also observed outbursts in the cataclysmic variables B7 and B8 (Kaluzny et
al. 1997).Comment: 15 pages LaTeX, including 8 PostScript figures and 3 tables. More
discussion added on the implications for transit detection. Accepted for
publication in the Astronomical Journal. Version with full resolution figures
available through ftp at
ftp://cfa-ftp.harvard.edu/pub/bmochejs/PISCES/papers/1_N6791
The EXPLORE Project I: A Deep Search for Transiting Extrasolar Planets
(Abridged) We discuss the design considerations of the EXPLORE (EXtra-solar
PLanet Occultation REsearch) project, a series of transiting planet searches
using 4-m-class telescopes to continuously monitor a single field of stars in
the Galactic Plane in each ~2 week observing campaign. We discuss the general
factors which determine the efficiency and the number of planets found by a
transit search, including time sampling strategy and field selection. The
primary goal is to select the most promising planet candidates for radial
velocity follow-up observations. We show that with very high photometric
precision light curves that have frequent time sampling and at least two
detected transits, it is possible to uniquely solve for the main parameters of
the eclipsing system (including planet radius) based on several important
assumptions about the central star. Together with a measured spectral type for
the star, this unique solution for orbital parameters provides a powerful
method for ruling out most contaminants to transiting planet candidates. For
the EXPLORE project, radial velocity follow-up observations for companion mass
determination of the best candidates are done on 8-m-class telescopes within
two or three months of the photometric campaigns. This same-season follow-up is
made possible by the use of efficient pipelines to produce high quality light
curves within weeks of the observations. We conclude by presenting early
results from our first search, EXPLORE I, in which we reached <1% rms
photometric precision (measured over a full night) on ~37,000 stars to I <=
18.2.Comment: accepted by ApJ. Main points unchanged but more thorough discussion
of some issues. 36 pages, including 14 figure
The three-dimensional Ising model: A paradigm of liquid-vapor coexistence in nuclear multifragmentation
Clusters in the three-dimensional Ising model rigorously obey reducibility
and thermal scaling up to the critical temperature. The barriers extracted from
Arrhenius plots depend on the cluster size as where
is a critical exponent relating the cluster size to the cluster
surface. All the Arrhenius plots collapse into a single Fisher-like scaling
function indicating liquid-vapor-like phase coexistence and the univariant
equilibrium between percolating clusters and finite clusters. The compelling
similarity with nuclear multifragmentation is discussed.Comment: (4 pages, 4 figures
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