The relationship between climatic variables and wood structure in Pinus halepensis Mill.

Summary The weekly increments under various conditions of a dozen of 30 to 60 years old Halep pines grown in the Lecce area have been measured during two years with a band dendrometer. The data have been compared with the X-ray density of a stem in radial direction, the weekly precipitations and the integrated temperature excess above 8°C. We have found thatgrowth rate behaviour is practically the same for all the pines considered. This indicate a strict dependence of growth on external factors such as climate and other environmental conditions. Vegetation activity does not seem to have regular dormancy periods: it stops when temperature and humidity become prohibitive and resumes as soon as they become favourable. The volume of wood formed in late-season (July–January) equals more or less that of early-season (February–June), whereas the wood mass and the number of cells in late-season is nearly double of that in early-season. During periods of high cambial activity one observes a lower cell lignification. However, on the whole, the photoperiodicity hypothesis in lignification seems to be confirmed. The growth rate appears inversely related to density. The lignification process appears to extend to the outer xylem layer of 1–2 mm and seems most effective during dry and warm seasons when cambial activity is low. Density wriggles appear to derive from combined variations of cambial activity, cell size and lignification, mostly corresponding to environmental events such as periods of drought or of cold weather. Finally, during the dry seasons we find that a precipitation event is generally followed within a time less than a week, by an increase of growth rate. Whereas during the wet season the growth rate variation is very similar to that of temperature excess.With 6 Figures     

Recognition of objects and position recovery from microdensitometer measurements of large field plates

The Coma region on a glass copy of the Palomar Sky Survey has been scanned by the PDS microdensitometer at the Napoli Observatory. A method is described for obtaining the photometric parameters and positions of the images: 12 316 objects have been found. The repositioning of the scanner over the computed coordinates is satisfatory. AGK3 stars were considered to evaluate the plate constants and the precision. Comparison with Dressel and Condon's positions of galaxies gives a r.m.s. scatter consistent with the internal error of the published list.     

BVR photometry of the distant cluster of galaxies a 665

Byurakan Astrophysical Observatory; Osservatoria Astronomico di Roma. Published in English in Astrofizika, Vol. 31, No. 3, pp. 437–446, November–December, 1989 and reprinted here with minor editorial changes.     

Further observations of radio sources from the BG survey. II. Mainly extragalactic

New observations of six fields from the low galactic latitude BG survey are presented. The radio sources within each of these fields appear to be of a predominantly extragalactic nature. However, one object is in close positional proximity to the pulsar 1922 + 20 and the possibility of their association is considered. The extended source BGE 0323 + 65 is shown to be unlikely to exist.     

A DNA tracer used in column tests for hydrogeology applications

Tracing techniques are commonly used to investigate groundwater quality and dynamics, as well as to measure the hydrogeological parameters of aquifers. The last decade has seen a growing interest in environmentally friendly tracers, including single-stranded DNA molecules. In this study, an electrolytic tracer and a synthetic DNA tracer are comparatively evaluated in laboratory scale tests to assess their potential application in field studies aimed at investigating groundwater environments. A real-time quantitative Polymerase Chain Reaction assay was developed and optimized to detect and quantify the DNA tracer, while tracer column tests were performed to investigate the DNA tracer behavior and to compare it to the electrolytic tracer. The results show that the DNA tracer has an almost pure convective flow, while the KCl tracer experiences dispersive behavior. The tracing method proposed can be applied in hydrogeological field studies involving calcareous fractured rock systems, with the DNA tracer particularly suitable in tracing karst systems, which are often characterized by several conduits of flow. To test the DNA tracer in operation, a preliminary test was conducted in the field.     

Variations of Temperature and Precipitation in Italy from 1866 to 1995

Summary Series of annual and seasonal temperature and precipitation representing respectively northern and southern Italy are compared for trend, interannual variability and periodicity in the period 1866–1995. Temperature and precipitation trends are almost always anticorrelated except in winter in the North where an anomalous behavior is evident till about 1980. The result is that the Italian climate has become warmer and drier especially in the South since about 1930.The interannual variability does not present significant maxima, but only minima that cannot be related tothe start of a trend either for temperature or for precipitation. The power spectra of the series show broad significant peaks containing the quasi-biennial oscillation and other well known periodicities probably due to solar cycles or to the North Atlantic ocean-atmosphere oscillation (NAO). Received December 16, 1998 Revised October 21, 1999     

The 18 June 1997 Companion supercells: Multiparametric Doppler radar analysis

Summary ?On 18 June 1997 two simultaneous supercells 50 km apart swept the Po valley W-NW to E-SE. An exceptional hailfall lasted for more than 3 hours over a strip 200 km wide. There are no records of companion supercells over northern Italy, a fact that attributes to the present observations a considerable meteorological interest. The forcing due to a baroclinic wave disturbance created the synoptic conditions favourable for storm development. A closer mesoscale analysis conducted using the Local Analysis and Prediction System (LAPS) indicates that the interaction of the storm systems with the low-level frontal high-humidity band is a key aspect of their evolution. The operational polarimetric Doppler weather radar of S. Pietro Capofiume was used for a volumetric analysis of the storm system focusing on the microphysical and dynamical structure, and wind patterns. Reflectivity and Doppler wind fields document the transition from multicell to supercell phase for one of the storms. Differential reflectivity (Z_DR) fields are examined. Positive Z_DR columns are detected in connection with the storms strong updraft. Flare echoes hint to the presence of substantial hailshafts. The spectrum width field is used to investigate internal motions. Limited dual Doppler analysis is carried out and results are discussed in terms of storm evolution properties. Received June 30, 1999/Revised February 3, 2000     

Two-color photometry of clusters of galaxies. III. A2256

Osservatorio Astronomico di Roma; Byurakan Astrophysical Observatory. Published in English in Astrofizika, Vol. 29, No. 2, pp. 232–246, September–October, 1988.