Kinematic characteristics of hailstorms in Northern Greece

International audienceThe purpose of this study is the analysis of radar data, digitally recorded, during an operational hail suppression program in the region of Central Macedonia, Greece, for the warm period of the years 1997?2001. Kinematic characteristics, such as lifetime and distance traveled by hailstorms, as well as direction of motion and speed, have been related to type of storms and season. It has been found that singlecells are short-lived and travel short distances, while multicells are long-lived and travel long distances. On the contrary, their corresponding speed distributions are similar. The deviation of the direction of motion from mean wind is smaller for singlecells than for multicells. September and July exhibit the maximum and minimum average storm speeds as a direct implication of synoptic disturbances passage and convection, prevailing respectively. Finally, storms overcoming orographic barriers decelerate in general on the windward side and accelerate on the lee side of mountains

Characteristics of the extreme warm and cold days over Greece

An attempt is made to study the characteristics of the extreme warm and cold days over the major area of Greece. To meet this objective, the daily maximum and minimum air temperature values are used, obtained from seventeen (17) synoptic weather stations, covering the broad study area. The extreme warm and cold days are identified based upon the proposed and adopted criteria, which are applied for the period 1961–2000. Seven regional decadal indices measuring the frequency of occurrence, the magnitude and the intensity of the extreme temperature values are calculated. The study of the indices revealed that after the 70' the frequency of occurrence and the intensity of cold days follow a negative trend, as opposed to the frequency of occurrence and the intensity of the warm days that follow a positive trend. Moreover, the proposed indices confirm the cooling conditions that Greece experienced in the 70's and early 80's and the warming trend afterwards

Learning from Only Positive and Unlabeled Data to Detect Lesions in Vascular CT Images

International audienc

Impact of Central Obesity on the Estimation of Carotid-Femoral Pulse Wave Velocity.

BACKGROUND: Studies have found that central obesity is associated with higher carotid-femoral pulse wave velocity (PWV). However, traveled distance (TD) measured over the body surface can be substantially overestimated with wider waist circumference (WC). We sought to investigate whether central obesity biases the estimation of PWV and whether this bias explains the association between PWV and different measures of adiposity. METHODS: Seven hundred eleven participants (49.5% men) from the Baltimore Longitudinal Study of Aging with PWV, anthropometrics, and quantification of different fat depots by computed tomography and dual x-ray absorptiometry were included. TD and relative PWV were estimated with a tape measure over the body surface or linear distances taken from radiological images, unaffected by obesity. RESULTS: A significant association was found between wider WC and a greater difference between the 2 TD measurements and their respective PWV in both sexes (r 65 0.34; P < 0.001). This overestimation bias appeared to be generally higher in women than men (0.27 m/sec for each unit increase in WC; P < 0.0001). When TD estimated over the body surface was used to calculate PWV, greater WC, total body fat, subcutaneous fat, and visceral fat were all associated with higher PWV (P < 0.05 for all). However, when PWV was calculated using TD estimated from radiological images or body height, only the association with visceral fat held significant. CONCLUSIONS: When TD is measured over the body surface, the role of obesity on PWV is substantially overestimated. After accounting for this bias, PWV was still independently associated with visceral fat but not with other measures of adiposity, confirming its contribution to arterial stiffening