Oratio de hominis dignitate = Mowa o godności człowieka

To początkowy fragment mowy O godności człowieka Pico della Mirandoli." Wstępem poprzedział Danilo Facca, przełożyli Zbigniew Nerczuk i Mikołaj Olszewski. This is an excerpt from the Polish translation of Pico della Mirandola's De dignitate hominis. The preface to the translation by Danilo Facca. Translation by Zbigniew Nerczuk and Mikołaj Olszewski

A Search for Old Star Clusters in the Large Magellanic Cloud

We report the first results of a color-magnitude diagram survey of 25 candidate old LMC clusters. For almost all of the sample, it was possible to reach the turnoff region, and in many clusters we have several magnitudes of the main sequence. Age estimates based on the magnitude difference $\delta T_1$ between the giant branch clump and the turnoff revealed that no new old clusters were found. The candidates turned out to be of intermediate age (1-3 Gyr) We show that the apparently old ages as inferred from integrated UBV colors can be explained by a combination of stochastic effects produced by bright stars and by photometric errors for faint clusters lying in crowded fields. The relatively metal poor candidates from the CaII triplet spectroscopy also turned out to be of intermediate age. This, combined with the fact that they lie far out in the disk, yields interesting constraints regarding the formation and evolution of the LMC disk. We also study the age distribution of intermediate age and old clusters This homogeneous set of accurate relative ages allows us to make an improved study of the history of cluster formation/destruction for ages $>1$Gyr. We confirm previous indications that there was apparently no cluster formation in the LMC during the period from 3-8 Gyr ago, and that there was a pronounced epoch of cluster formation beginning 3 Gyrs ago that peaked at about 1.5 Gyrs ago. Our results suggest that there are few, if any, genuine old clusters in the LMC left to be found.Comment: LaTeX, to be published in Nov. 1997 Astronomical Journa

Ages and Metallicities of Star Clusters and Surrounding Fields in the Outer Disk of the Large Magellanic Cloud

We present Washington system C,T_1 CMDs of 13 star clusters and their surrounding fields which lie in the outer parts of the LMC disk. Ages are determined by means of the magnitude difference between the giant branch clump and the turnoff, while metallicities are derived from the location of the giant and subgiant branches as compared to fiducial star clusters. We find that in most cases the stellar population of each star cluster is quite similar to that of the field where it is embedded. Three particular fields present remarkable properties: (i) The so far unique cluster ESO121-SC03 at ~9 Gyr has a surrounding field which shares the same properties. (ii) The field surrounding the far eastern intermediate age cluster OHSC37 is noteworthy in the sense that we do not detect any evidence of LMC stars. (iii) The fields of SL388 and SL509 present CMDs with a secondary clump ~0.45 mag fainter than the dominant intermediate age clump, suggesting a stellar population component located behind the LMC disk at a distance comparable to that of the SMC. The mean metallicity derived for the intermediate age outer disk clusters is =-0.7 and for their surrounding fields =-0.6. These values are significantly lower than found by Olszewski et al. (1991, AJ, 101, 515) for a sample of clusters of similar age, but are in good agreement with several recent studies. A few clusters stand out in the age--metallicity relation in the sense that they are intermediate age clusters at relatively low metallicity ([Fe/H]~-1).Comment: LaTeX, to be published in July, 1998 Astronomical Journa

MOND and the seven dwarfs

Gerhard had recently analyzed the data on seven dwarf spheroidals, and concluded that these disagree with the predictions of MOND. We contend that this conclusion is anything but correct. With new data for three of the dwarfs the observations of all dwarfs are in compelling agreement with the predictions of MOND. Gerhard found MOND M/L values that fall around a few solar units, as expected if MOND is a valid alternative to dark matter. His sole cause for complaint was that some of his MOND M/L values were still outside the range of ``reasonable'' stellar values. This, we say, was easily attributable to uncertainties in the data, such as in the velocity dispersions, luminosities, core radii, etc., and in the assumptions that underlie the analysis, such as isotropic velocity distribution, light-distribution fits, etc.. There are now new, much improved determinations of the velocity dispersions for three of the dwarfs, in particular for the two dwarfs for which Gerhard found high MOND M/L values. In fact, within just the quoted errors on the velocity dispersions and the luminosities, the MOND M/L values for all seven dwarfs are now perfectly consistent with stellar values, with no need for dark matter.Comment: 10 pages; Latex; requires aaspp.sty, attached at the end

A nonmanipulable test

A test is said to control for type I error if it is unlikely to reject the data-generating process. However, if it is possible to produce stochastic processes at random such that, for all possible future realizations of the data, the selected process is unlikely to be rejected, then the test is said to be manipulable. So, a manipulable test has essentially no capacity to reject a strategic expert. Many tests proposed in the existing literature, including calibration tests, control for type I error but are manipulable. We construct a test that controls for type I error and is nonmanipulable.Comment: Published in at http://dx.doi.org/10.1214/08-AOS597 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org