Search results for "Photometry"
showing 10 items of 797 documents
Radio observations of the HDFS region. IV.
2011
The Australia Telescope Hubble Deep Field-South (ATHDF-S) survey of the Hubble Deep Field-South (HDF-S) reaches sensitivities of ~10uJy at 1.4, 2.5, 5.2, and 8.7GHz, making the ATHDF-S one of the deepest surveys ever performed with the Australia Telescope Compact Array (ATCA). Here, we present the optical identifications of the ATHDF-S radio sources using data from the literature. We find that ~66% of the radio sources have optical counterparts to I=23.5mag. Deep Hubble Space Telescope (HST) imaging of the area identifies a further 12% of radio sources. We present new spectroscopic observations for 98 of the radio sources and supplement these spectroscopic redshifts with photometric ones ca…
Rosat North Ecliptic survey stellar population
2007
X-ray surveys are a very efficient mean of detecting young stars and therefore allow us to study the young stellar population in the solar neighborhood and the local star formation history in the last billion of years. We want to study the young stellar population in the solar neighborhood, to constrain its spatial density and scale height as well as the recent local star formation history. We analyze the stellar content of the ROSAT North Ecliptic Pole survey, and compare the observations with the predictions derived from stellar galactic model. Since the ROSAT NEP survey is sensitive at intermediate fluxes is able to sample both the youngest stars and the intermediate age stars (younger t…
BVRI photometry of high-mass X-ray binaries
2015
We present photometric observations of the field around the optical counterparts of high-mass X-ray binaries. Our aim is to study the long-term photometric variability in correlation with their X-ray activity and derive a set of secondary standard stars that can be used for time series analysis. We find that the donors in Be/X-ray binaries exhibit larger amplitude changes in the magnitudes and colours than those hosting a supergiant companion. The amplitude of variability increases with wavelength in Be/X-ray binaries and remains fairly constant in supergiant systems. When time scales of years are considered, a good correlation between the X-ray and optical variability is observed. The X-ra…
An overview of and issues with sky radiometer technology and SKYNET
2020
This paper is an overview of the progress in sky radiometer technology and the development of the network called SKYNET. It is found that the technology has produced useful on-site calibration methods, retrieval algorithms, and data analyses from sky radiometer observations of aerosol, cloud, water vapor, and ozone. A formula was proposed for estimating the accuracy of the sky radiometer calibration constant F0 using the improved Langley (IL) method, which was found to be a good approximation to observed monthly mean uncertainty in F0, around 0.5 % to 2.4 % at the Tokyo and Rome sites and smaller values of around 0.3 % to 0.5 % at the mountain sites at Mt. Sarasw…
Aerosol closure study by lidar, sun photometry, and airborne optical counters during DAMOCLES field campaign at El Arenosillo sounding station, Spain
2011
We present a comparison of aerosol properties derived from in situ and remote sensing instruments during DAMOCLES campaign, aimed at investigating the equivalence between the instrumentation and methodologies employed by several Spanish groups to study atmospheric aerosols at a regional background site. The complete set of instruments available during this closure experiment allowed collecting a valuable high-resolution aerosol measurement data set. The data set was augmented with airborne in situ measurements carried out in order to characterize aerosol particles during the midday of 29 June 2006. This work is focused on aerosol measurements using different techniques of high-quality instr…
Deconvolution procedure of the UV-vis spectra. A powerful tool for the estimation of the binding of a model drug to specific solubilisation loci of b…
2015
UV-vis-spectra evolution of Nile Red loaded into Tween 20 micelles with pH and [Tween 20] have been analysed in a non-conventional manner by exploiting the deconvolution method. The number of buried sub-bands has been found to depend on both pH and bio-surfactant concentration, whose positions have been associated to Nile Red confined in aqueous solution and in the three micellar solubilisation sites. For the first time, by using an extended classical two-pseudo-phases-model, the robust treatment of the spectrophotometric data allows the estimation of Nile Red binding constant to the available loci. Hosting capability towards Nile Red is exalted by the pH enhancement. Comparison between bin…
Chromatographic separation of chlorthalidone enantiomers using β-cyclodextrins as chiral additives
2000
Different beta-cyclodextrins have been tested as chiral additives in the mobile phase for the chromatographic analysis of chlorthalidone enantiomers in a C18 LiChrospher (125 x 4 mm I.D.) column. The effect on enantioresolution of different parameters was studied: composition of the mobile phase (percentage of organic solvent, type of buffer and pH), mobile phase flow-rate, and type and concentration of beta-cyclodextrin. A 25:75 mixture of methanol and 0.1 M phosphate buffer, pH 4, containing 2% triethylamine (v/v), and 12.5 mM beta-cyclodextrin, at a flow-rate of 0.8 ml/min, was found to be the best option for the resolution of chlorthalidone enantiomers. Under such conditions, linear cal…
Low temperature optical spectroscopy of low-spin ferric hemeproteins
1996
We report the Soret absorption spectra (500-350 nm) of the cyanomet derivatives of human hemoglobin and horse myoglobin, in the temperature range 300-20 K and in two different solvents (65% v/v glycerol-water or 65% v/v ethylene glycol-water). In order to obtain information on stereodynamic properties of active site of the two hemeproteins, we perform an analysis of the band profiles within the framework of electron-vibrations coupling. This approach enables us to single out the various contributions to the spectral bandwidth, such as those arising from non-radiative decay of the excited electronic state (homogeneous broadening) and from the coupling of the electronic transition i) with hig…
Sedimentation properties of chitosomal chitin synthetase from the wild-type strain and the 'slime' variant of Neurospora crassa.
1989
Marked differences in the pattern of sedimentation of cellular structures were observed after isopycnic centrifugation of crude cell-free preparations from the Neurospora crassa wall-less 'slime' variant and mycelial wild-type strain. Kinetic studies of particle sedimentation showed that the various types of subcellular components, as revealed by turbidity, UV absorption, polypeptide patterns, and chitin synthetase activity determinations, sediment independently of one another. An important feature was the finding that chitin synthetase from 'slime' peaked at a median specific gravity of 1.1201 +/- 0.0036, whereas that from wild-type strain sedimented at a higher buoyant density (specific g…
In-vitro test system for the evaluation of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibitors based on a single HPLC run with UV detect…
2001
Objective and Design: The aim of this study was to develop a new, whole-cell test system which is easy to handle and requires a standard equipment for the parallel screening of COX-1 and COX-2 inhibitors.¶Materials: Bovine aortic endothelial cells (BAECs).¶Treatment and methods: Unstimulated bovine aortic coronary endothelial cells (BAECs) were used as a source of COX-1 and BAECs pretreated with ASA (100 μM) and activated with phorbol myristate acetate (PMA) were used as a source of COX-2. The time- and concentration-dependent induction of COX-2 expression in the BAECs was evaluated by a kinetic profile (HPLC analysis) and detected by Western-Blot analysis using polyclonal antibodies agains…