Search results for "-type"
showing 10 items of 360 documents
Expression of HIP/PAP mRNA in Human Hepatoma Cell Lines
2002
The present study attempts to shed more light on the role of hepatocarcinoma-intestine-pancreas/pancreatic associated protein (HIP/PAP) in hepatoma cells. We initially examined, by reverse transcription-polymerase chain reaction (RT-PCR), the HIP/PAP transcripts present in human hepatoma cell lines of different origins and with different grades of differentiation and genetic profiles. We also used DNA sequencing analysis to investigate the structure of the HIP/PAP gene. Further investigation is necessary to define the role of HIP/PAP during the development of human hepatocellular carcinoma and to ascertain whether the use of different transcripts is helpful in regulating HIP/PAP expression …
Parametric nonlinear singular Dirichlet problems
2019
Abstract We consider a nonlinear parametric Dirichlet problem driven by the p -Laplacian and a reaction which exhibits the competing effects of a singular term and of a resonant perturbation. Using variational methods together with suitable truncation and comparison techniques, we prove a bifurcation-type theorem describing the dependence on the parameter of the set of positive solutions.
Kinetics and state-dependent effects of verapamil on cardiac L-type calcium channels.
1996
The voltage dependence and the kinetics of block by verapamil of L-type calcium current (ICa) were investigated in ventricular myocytes from rat hearts using the whole-cell patch-clamp technique. ICa was elicited repetitively in response to depolarizing voltage pulses from -80 mV to 0 mV at different pulse intervals and durations. Verapamil reduced the magnitude of ICa in a frequency-dependent manner without tonic component. The time course of ICa remained unchanged suggesting that not open but inactivated channels were affected by the drug. The interaction of verapamil with inactivated channels was investigated by the application of twin pulses. In the presence of verapamil, the duration o…
Experimental and theoretical study on the optical properties of LaVO4 crystals under pressure
2018
We report optical absorption and luminescence measurements in pure and trivalent neodymium (Nd3+) doped LaVO4 crystals up to 25 GPa. Nd3+ luminescence has been employed as a tool to follow the structural changes in the crystal. We also present band-structure and crystal-field calculations that provide the theoretical framework to accurately explain the observed experimental results. In particular, both optical absorption and luminescence measurements evidence that a phase transition takes place close to 12 GPa. They also provide information on the pressure dependence of the band-gap as well as the emission lines under compression. We found drastic changes in the optical properties of LaVO4 …
The cool Galactic R Coronae Borealis variable DY Persei
2005
Results of first CCD photometry during the recent deep light decline, and high-resolution spectroscopy, are presented for DY Persei. The spectra show variable blueshifted features in the sodium D lines. The C lines are strong whereas neutron- capture elements are not enhanced. The isotopic 13 CN(2, 0) lines relative to 12 CN are of similar strength with those for the carbon star U Hya. All these confirm the RCB nature of DY Per and the existence of ejected clouds. At least two clouds are revealed at −197.3 and −143.0 km s −1 . A star was detected about 0. 4t o the west and 2 . 5 to the north from DY Per. This anonymous companion, with observed colour indices (B − V) = 0.68 and (V − R) � 1…
Fourier analysis of HD 49330 CoRoT light curve
2009
Be stars undergo outbursts producing a circumstellar disk from the ejected material. The beating of non-radial pulsations has been put forward as a possible mechanism of ejection. We analyze the pulsational behavior of the early B0.5IVe star HD 49330 observed during the first CoRoT long run towards the Galactical anticenter (LRA1). This Be star is located close to the lower edge of the {beta} Cephei instability strip in the HR diagram and showed a 0.03mag outburst during the CoRoT observations. It is thus an ideal case for testing the aforementioned hypothesis.
Volatility Effects on the Escape Time in Financial Market Models
2008
We shortly review the statistical properties of the escape times, or hitting times, for stock price returns by using different models which describe the stock market evolution. We compare the probability function (PF) of these escape times with that obtained from real market data. Afterwards we analyze in detail the effect both of noise and different initial conditions on the escape time in a market model with stochastic volatility and a cubic nonlinearity. For this model we compare the PF of the stock price returns, the PF of the volatility and the return correlation with the same statistical characteristics obtained from real market data.
Search for Low-mass Companions to X-ray Emitting A-type Stars
2007
There is no obvious theory that would explain X-ray emission from main-sequence A-type stars. Therefore, the X-ray emission identified with these stars on basis of low spatial resolution X-ray observations is usually attributed to magnetic activity from unknown late-type companion stars. We systematically study the literature and public 2MASS data in search for binaries among A stars. This way, we identify new candidate counterparts for the X-ray sources in at least 60% of the A-type stars claimed to be detected in the ROSAT All-Sky Survey. There is marginal evidence that this fraction decreases from early to late A spectral type, possibly indicating the onset of intrinsic X-ray emission fo…
Be stars in open clusters. I. uvby $ ^{\bf \beta}$ photometry
1996
We present uvby β photometry for Be stars in eight open clusters and two OB associations. It is shown that Be stars occupy anomalous positions in the photometric diagrams, which can be explained in terms of the circumstellar continuum radiation contribution to the photometric indices. In the - M V plane Be stars appear redder than the non emission B stars, due to the additional reddening caused by the hydrogen free-bound and free-free recombination in the circumstellar envelope. In the c 0 - M V plane the earlier Be stars present lower c 0 values than absorption-line B stars, which is caused by emission in the Balmer discontinuity, while the later Be stars deviate towards higher c 0 values,…
The density of coronal plasma in active stellar coronae
2004
We have analyzed high-resolution X-ray spectra of a sample of 22 active stars observed with the High Energy Transmission Grating Spectrometer on {\em Chandra} in order to investigate their coronal plasma density. Densities where investigated using the lines of the He-like ions O VII, Mg XI, and Si XIII. While Si XIII lines in all stars of the sample are compatible with the low-density limit, Mg XI lines betray the presence of high plasma densities ($> 10^{12}$ cm$^{-3}$) for most of the sources with higher X-ray luminosity ($> 10^{30}$ erg/s); stars with higher $L_X$ and $L_X/L_{bol}$ tend to have higher densities at high temperatures. Ratios of O VII lines yield much lower densities …