50 research outputs found
Application of algal bioassays in the determination of eutrophic power of waste water (”Conclusions” only) [Translation from: 1g.Sanita pubbl. 31 257-267, 1975]
The best evidence for establishing the level of eutrophy of a water-body is its algal production which makes it possible to identify the type and the intensity of the eutrophication according to the kind and number of algal species present: when the number of algae exceeds half a million per litre then one speaks o an ”algal bloom”. The scope of the present research aims to verify if the alga Selenastrum capricornutum can be used as a test alga under our culture conditions and to determine the eutrophic level of the secondary effluent of a modern plant for the treatment of domestic discharge and to investigate the eventual ”limiting factors”. Finally this paper aims to study the effect on the secondary effluent of tertiary treatment carried out artificially in the laboratory
Infrared analysis and pressure measurements on a single loop pulsating heat pipe at different gravity levels
The APACHE survey hardware and software design: Tools for an automatic search of small-size transiting exoplanets
Small-size ground-based telescopes can effectively be used to look for transiting rocky planets around nearby low-mass M stars using the photometric transit method, as recently demonstrated for example by the MEarth project. Since 2008 at the Astronomical Observatory of the Autonomous Region of Aosta Valley (OAVdA), we have been preparing for the long-term photometric survey APACHE, aimed at finding transiting small-size planets around thousands of nearby early and mid-M dwarfs. APACHE (A PAthway toward the Characterization of Habitable Earths) is designed to use an array of five dedicated and identical 40-cm Ritchey-Chretien telescopes and its observations started at the beginning of summer 2012. The main characteristics of the survey final set up and the preliminary results from the first weeks of observations will be discussed
New Variable Stars Discovered by the APACHE Survey. II. Results After the Second Observing Season
Routinely operating since July 2012, the APACHE survey has celebrated its
second birthday. While the main goal of the Project is the detection of
transiting planets around a large sample of bright, nearby M dwarfs in the
northern hemisphere, the APACHE large photometric database for hundreds of
different fields represents a relevant resource to search for and provide a
first characterization of new variable stars. We celebrate here the conclusion
of the second year of observations by reporting the discovery of 14 new
variables.Comment: 25 pages, accepted for publication on The Journal of the American
Association of Variable Star Observers (JAVVSO
Photometric transit search for planets around cool stars from the western Italian Alps: A pilot study
[ABRIDGED] In this study, we set out to a) demonstrate the sensitivity to <4
R_E transiting planets with periods of a few days around our program stars, and
b) improve our knowledge of some astrophysical properties(e.g., activity,
rotation) of our targets by combining spectroscopic information and our
differential photometric measurements. We achieve a typical nightly RMS
photometric precision of ~5 mmag, with little or no dependence on the
instrumentation used or on the details of the adopted methods for differential
photometry. The presence of correlated (red) noise in our data degrades the
precision by a factor ~1.3 with respect to a pure white noise regime. Based on
a detailed stellar variability analysis, a) we detected no transit-like events;
b) we determined photometric rotation periods of ~0.47 days and ~0.22 days for
LHS 3445 and GJ 1167A, respectively; c) these values agree with the large
projected rotational velocities (~25 km/s and ~33 km/s, respectively) inferred
for both stars based on the analysis of archival spectra; d) the estimated
inclinations of the stellar rotation axes for LHS 3445 and GJ 1167A are
consistent with those derived using a simple spot model; e) short-term,
low-amplitude flaring events were recorded for LHS 3445 and LHS 2686. Finally,
based on simulations of transit signals of given period and amplitude injected
in the actual (nightly reduced) photometric data for our sample, we derive a
relationship between transit detection probability and phase coverage. We find
that, using the BLS search algorithm, even when phase coverage approaches 100%,
there is a limit to the detection probability of ~90%. Around program stars
with phase coverage >50% we would have had >80% chances of detecting planets
with P0.5%, corresponding to minimum
detectable radii in the range 1.0-2.2 R_E. [ABRIDGED]Comment: 23 pages, 17 figures, 7 tables. Accepted for publication in MNRA