985 research outputs found
Antitumor effect of lysine-isopeptides
Isopeptides (ε-peptides) of lysine, with a given Mw and low polydispersity (10–400 units), were synthesized to study the relationship between their chemical structure and biological effect. The designed compounds were of high purity, low polydispersity and high stereochemical purity. The effect of the compounds was tested on a human erythroleukemia cell line (K-562) and on four transplantable mouse tumors (L1210 lymphoid leukemia, P38 macrophage derived tumor, Ehrlich ascites carcinoma, Lewis lung tumor /LLT/). In case of the L1210 and P388 tumors and the Ehrlich carcinoma, survival of the animals was used as an indicator of the effect. In case of the Lewis lung tumor, the number and size of metastases in the lung and/or liver of treated and untreated mice were used as indicators. The polymers of polymerisation degree 80–120 (Mw 10.2–15.4 KD) showed the strongest antiproliferative effect both on K562 cells and the tumors growing in vivo. This effect was manifest with a significantly higher survival rate as compared to the control (L1210, P38, Ehrlich ascites), furthermore, by a decrease in the number and size of liver and lung metastases (LLT)
Transport on randomly evolving trees
The time process of transport on randomly evolving trees is investigated. By
introducing the notions of living and dead nodes a model of random tree
evolution is constructed which describes the spreading in time of objects
corresponding to nodes. By using the method of the age-dependent branching
processes we derive the joint distribution function of the number of living and
dead nodes, and determine the correlation between these node numbers as a
function of time. Also analyzed are the stochastic properties of the end-nodes;
and the correlation between the numbers of living and dead end-nodes is shown
to change its character suddenly at the very beginning of the evolution
process. The survival probability of random trees is investigated and
expressions are derived for this probability.Comment: 16 pages, 8 figures, published in Phys. Rev. E 72, 051101 (2005
Pushing the limits, episode 2: K2 observations of extragalactic RR Lyrae stars in the dwarf galaxy Leo IV
We present the first observations of extragalactic pulsating stars in the K2
ecliptic survey of the Kepler space telescope. Variability of all three RR
Lyrae stars in the dwarf spheroidal galaxy Leo IV were successfully detected,
at a brightness of Kp~21.5 mag, from data collected during Campaign 1. We
identified one modulated star and another likely Blazhko candidate with periods
of 29.8+-0.9 d and more than 80 d, respectively. EPIC 210282473 represents the
first star beyond the Magellanic Clouds for which the Blazhko period and
cycle-to-cycle variations in the modulation were unambiguously measured.The
photometric [Fe/H] indices of the stars agree with earlier results that Leo IV
is a very metal-poor galaxy. Two out of three stars blend with brighter
background galaxies in the K2 frames. We demonstrate that image subtraction can
be reliably used to extract photometry from faint confused sources that will be
crucial not only for the K2 mission but for future space photometric missions
as well.Comment: 8 pages, 6 figures, accepted for publication in the Astrophysical
Journal. Light curves can be downloaded from http://konkoly.hu/KIK/data.htm
A dohányzás és az anyagi helyzet összefüggése serdülőkori és felnőttkori terhesség esetén
INTRODUCTION: Smoking occurs frequently during pregnancy, thereby putting mother and child at health risks. Low socio-economic status is a risk factor for smoking. AIM: To investigate the relationship between smoking and low income in teenage and adult pregnancy, which is an important measure of poor socioeconomic status. METHOD: The authors used subject-level data from the US NSDUH database, which contains information on pregnancies and smoking. RESULTS: Teenage pregnancy is associated with higher, whereas adult pregnancy with lower prevalence of smoking, compared to the age-matched female population. The association between income and smoking is age-dependent. Among adults there is an inverse relationship (high income -- low-risk of smoking), while in teenage pregnancy smoking increases with income. CONCLUSIONS: To investigate in teenage and adult pregnancy the relationship between smoking and low income, which is an important measure of poor socio-economic status. Higher socioeconomic status may be associated with risky behaviour, thereby increasing both the risk of smoking and early pregnancy
First observations of W Virginis stars with K2: detection of period doubling
We present the first analysis of W Vir stars observed by the Kepler space
telescope in the K2 mission. Clear cycle-to-cycle variation were detected in
the light curves of KT Sco and the globular cluster member M80-V1. While the
variations in the former star seems to be irregular on the short time scale of
the K2 data, the latter appears to experience period doubling in its pulsation.
Ground-based colour data confirmed that both stars are W Vir-type pulsators,
while a comparison with historical photometric time-series data revealed
drastic period changes in both stars. For comparison we reexamine ground-based
observations of W Vir, the prototype of the class, and conclude that it shows
period doubling instead of mode beating. These results support the notion that
nonlinear dynamics plays an important role in the pulsation of W Virginis-type
stars.Comment: 8 pages, 7 figures, accepted for publication in MNRA
Optimized Herschel/PACS photometer observing and data reduction strategies for moving solar system targets
The "TNOs are Cool!: A survey of the trans-Neptunian region" is a Herschel
Open Time Key Program that aims to characterize planetary bodies at the
outskirts of the Solar System using PACS and SPIRE data, mostly taken as
scan-maps. In this paper we summarize our PACS data reduction scheme that uses
a modified version of the standard pipeline for basic data reduction, optimized
for faint, moving targets. Due to the low flux density of our targets the
observations are confusion noise limited or at least often affected by bright
nearby background sources at 100 and 160\,m. To overcome these problems we
developed techniques to characterize and eliminate the background at the
positions of our targets and a background matching technique to compensate for
pointing errors. We derive a variety of maps as science data products that are
used depending on the source flux and background levels and the scientific
purpose. Our techniques are also applicable to a wealth of other Herschel solar
system photometric observations, e.g. comets and near-Earth asteroids. The
principles of our observing strategies and reduction techniques for moving
targets will also be applicable for similar surveys of future infrared space
projects.Comment: Accepted for publication in Experimental Astronom
Demenciák megelőzésének gyógyszeres és egyéb lehetőségei: irodalmi összefoglaló
BACKGROUND: At present 34 million people live with Alzheimer's disease around the world. This figure is expected to triple in the next 40 years. The major cause of this increase is the well-known aging of the society in Europe and in the US as well. AIMS AND METHODS: In this paper we review the results of the last 10 years, and discuss those pharmaceutical and other methods, which can be effective in the prevention of dementias. RESULTS: The most important pharmaceutical agents are beta secretase inhibitors, and active and passive immunizations. Several drugs in these groups are in phase III at the moment. The results from studies with intranasal insulin are also encouraging. As a non-drug option Mediterranean diet can be effective. However at present cognitive trainings seem to be the most effective in the prevention of dementias. These remediation therapies are based on the lifelong plasticity of the human brain. CONCLUSIONS: In summary we can conclude that there are promising drug developments in progess for the prevention of dementias, but the breakthrough has not been achieved yet. At present the best option is decreasing risk factors, that is treatment of hypertension, prevention of obesity and diabetes, and cognitive trainings are recommended for prevention
On the Effects of a Bulk Perturbation on the Ground State of 3D Ising Spin Glasses
We compute and analyze couples of ground states of 3D spin glasses before and
after applying a volume perturbation which adds to the Hamiltonian a repulsion
from the true ground state. The physical picture based on Replica Symmetry
Breaking is in excellent agreement with the observed behavior.Comment: 4 pages including 5 .ps figure
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