631 research outputs found

    Behavior and the Response of Cancer Cells on Anticancer Drug Treatment Monitored with Microelectrode Array

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    AbstractA cell-based impedance biosensor using microelectrode array has been developed for monitoring cellular activities of MCF-7 breast cancer cells and evaluating drug-induced apoptosis. Using this device, different activities of cells such as cell attachment, adhesion, and spreading are monitored by measuring impedance spectra and interpreting the data using an electrical equivalent circuit. In order to demonstrate pharmaceutical relevance, the cells were treated with 25ÎŒM of anti-cancer drug Cisplatin. It was found that cell spreading caused a significant increase of impedance magnitude in the frequency range between 10kHz and 100kHz during 23h of incubation, which is reversed after 24h treatment with Cisplatin. This reversal is attributed to cell apoptosis, which is confirmed by microscopic observation of the cells

    Cluster Interpretation of Properties of Alternating Parity Bands in Heavy Nuclei

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    The properties of the states of the alternating parity bands in actinides, Ba, Ce and Nd isotopes are analyzed within a cluster model. The model is based on the assumption that cluster type shapes are produced by the collective motion of the nuclear system in the mass asymmetry coordinate. The calculated spin dependences of the parity splitting and of the electric multipole transition moments are in agreement with the experimental data.Comment: 29 pages, 10 figure

    Anatomy of Spin-Transfer Torque

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    Spin-transfer torques occur in magnetic heterostructures because the transverse component of a spin current that flows from a non-magnet into a ferromagnet is absorbed at the interface. We demonstrate this fact explicitly using free electron models and first principles electronic structure calculations for real material interfaces. Three distinct processes contribute to the absorption: (1) spin-dependent reflection and transmission; (2) rotation of reflected and transmitted spins; and (3) spatial precession of spins in the ferromagnet. When summed over all Fermi surface electrons, these processes reduce the transverse component of the transmitted and reflected spin currents to nearly zero for most systems of interest. Therefore, to a good approximation, the torque on the magnetization is proportional to the transverse piece of the incoming spin current.Comment: 16 pages, 8 figures, submitted to Phys. Rev.

    New results from the NA57 experiment

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    We report results from the experiment NA57 at CERN SPS on hyperon production at midrapidity in Pb-Pb collisions at 158 AA GeV/cc and 40 AA GeV/cc. Λ\Lambda, Ξ\Xi and Ω\Omega yields are compared with those from the STAR experiment at the higher energy of the BNL RHIC. Λ\Lambda, Ξ\Xi, Ω\Omega\ and preliminary KS0K_S^0 transverse mass spectra are presented and interpreted within the framework of a hydro-dynamical blast wave model.Comment: 8 pages, 3 figures, contribution to the proceedings of The XXXVIIIth Rencontres de Moriond "QCD and High Energy Hadronic Interactions

    Strange particle production in 158 and 40 AA GeV/cc Pb-Pb and p-Be collisions

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    Results on strange particle production in Pb-Pb collisions at 158 and 40 AA GeV/cc beam momentum from the NA57 experiment at CERN SPS are presented. Particle yields and ratios are compared with those measured at RHIC. Strangeness enhancements with respect to p-Be reactions at the same beam momenta have been also measured: results about their dependence on centrality and collision energy are reported and discussed.Comment: Contribution to the proceedings of the "Hot Quarks 2004" Conference, July 18-24 2004, New Mexico, USA, submitted to Journal of Physics G 7 pages, 5 figure

    Effects of follicular phase exercise on luteinizing hormone pulse characteristics in sedentary eumenorrhoeic women

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    OBJECTIVE Current studies reveal little regarding the Inception of exercise-induced LH changes during physical training. This study aimed to assess the susceptibility of the hypothalamic–pituitary axis to the acute physical stress of exercise in untrained, physically inactive women. The acute effects of submaximal endurance exercise upon the pulsatile LH secretion in the follicular phase were compared with those accompanying leisurely strolling for a similar time period. SUBJECTS All subjects were eumenorrhoelc, as determined by biphasic temperature patterns, detection of the urinary LH surge, and mid-luteal serum progesterone levels. Subjects were not physically active and had little history of strenuous exercise ( V o 2 max = 38·0 ± 1·8) (mean ± SEM) ml/kg/min). DESIGN All women completed a 13·5-hour pulsatility test which included three consecutive 20-minute runs on a treadmill at 50, 60 and 70% of the subjects’maximum oxygen uptake ( n = 16). Six of these same subjects completed a separate test on another occasion in which one hour of leisurely strolling was substituted for exercise. Blood was sampled every 10 minutes via an indwelling cannula for 4·5 hours before and 8 hours after one hour of exercise and or strolling. MEASUREMENTS A pulse algorithm (Pulsar) was used to quantify LH pulse characteristics. RESULTS Exercise produced no significant effects upon LH pulse frequency or mean serum LH concentration. However, exercise of moderate intensity caused a significant increase in LH pulse amplitude ( P < 0·05). Strolling produced no significant changes in LH secretion. CONCLUSION Acute exercise of moderate intensity in the follicular phase of untrained women is an insufficient stimulus to inhibit the GnRH pulse generator in the post-exercise period, yet may produce a slight stimulatory effect on the amount of LH released per pulsePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73507/1/j.1365-2265.1994.tb02794.x.pd

    VISIONS:the VISTA Star Formation Atlas I. Survey overview

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    VISIONS is an ESO public survey of five nearby (d &lt; 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carried out with the Visible and Infrared Survey Telescope for Astronomy (VISTA), using the VISTA Infrared Camera (VIRCAM), and collected data in the near-infrared passbands J (1.25 ÎŒm), H (1.65 ÎŒm), and KS (2.15 ÎŒm). With a total on-sky exposure time of 49.4h VISIONS covers an area of 650 deg2, it is designed to build an infrared legacy archive with a structure and content similar to the Two Micron All Sky Survey (2MASS) for the screened star-forming regions. Taking place between April 2017 and March 2022, the observations yielded approximately 1.15 million images, which comprise 19 TB of raw data. The observations undertaken within the survey are grouped into three different subsurveys. First, the wide subsurvey comprises shallow, large-scale observations and it has revisited the star-forming complexes six times over the course of its execution. Second, the deep subsurvey of dedicated high-sensitivity observations has collected data on areas with the largest amounts of dust extinction. Third, the control subsurvey includes observations of areas of low-to-negligible dust extinction. Using this strategy, the VISIONS observation program offers multi-epoch position measurements, with the ability to access deeply embedded objects, and it provides a baseline for statistical comparisons and sample completeness – all at the same time. In particular, VISIONS is designed to measure the proper motions of point sources, with a precision of 1 mas yr−1 or better, when complemented with data from the VISTA Hemisphere Survey (VHS). In this way, VISIONS can provide proper motions of complete ensembles of embedded and low-mass objects, including sources inaccessible to the optical ESA Gaia mission. VISIONS will enable the community to address a variety of research topics from a more informed perspective, including the 3D distribution and motion of embedded stars and the nearby interstellar medium, the identification and characterization of young stellar objects, the formation and evolution of embedded stellar clusters and their initial mass function, as well as the characteristics of interstellar dust and the reddening law

    VISIONS:the VISTA Star Formation Atlas I. Survey overview

    Get PDF
    VISIONS is an ESO public survey of five nearby (d &lt; 500 pc) star-forming molecular cloud complexes that are canonically associated with the constellations of Chamaeleon, Corona Australis, Lupus, Ophiuchus, and Orion. The survey was carried out with the Visible and Infrared Survey Telescope for Astronomy (VISTA), using the VISTA Infrared Camera (VIRCAM), and collected data in the near-infrared passbands J (1.25 ÎŒm), H (1.65 ÎŒm), and KS (2.15 ÎŒm). With a total on-sky exposure time of 49.4h VISIONS covers an area of 650 deg2, it is designed to build an infrared legacy archive with a structure and content similar to the Two Micron All Sky Survey (2MASS) for the screened star-forming regions. Taking place between April 2017 and March 2022, the observations yielded approximately 1.15 million images, which comprise 19 TB of raw data. The observations undertaken within the survey are grouped into three different subsurveys. First, the wide subsurvey comprises shallow, large-scale observations and it has revisited the star-forming complexes six times over the course of its execution. Second, the deep subsurvey of dedicated high-sensitivity observations has collected data on areas with the largest amounts of dust extinction. Third, the control subsurvey includes observations of areas of low-to-negligible dust extinction. Using this strategy, the VISIONS observation program offers multi-epoch position measurements, with the ability to access deeply embedded objects, and it provides a baseline for statistical comparisons and sample completeness – all at the same time. In particular, VISIONS is designed to measure the proper motions of point sources, with a precision of 1 mas yr−1 or better, when complemented with data from the VISTA Hemisphere Survey (VHS). In this way, VISIONS can provide proper motions of complete ensembles of embedded and low-mass objects, including sources inaccessible to the optical ESA Gaia mission. VISIONS will enable the community to address a variety of research topics from a more informed perspective, including the 3D distribution and motion of embedded stars and the nearby interstellar medium, the identification and characterization of young stellar objects, the formation and evolution of embedded stellar clusters and their initial mass function, as well as the characteristics of interstellar dust and the reddening law

    Evidence for a mixed mass composition at the `ankle' in the cosmic-ray spectrum

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    We report a first measurement for ultra-high energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the `ankle' at lg⁡(E/eV)=18.5−19.0\lg(E/{\rm eV})=18.5-19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A>4A > 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoured as the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth.Comment: Published version. Added journal reference and DOI. Added Report Numbe
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