SAWA experiment ? properties of mineral dust aerosol as seen by synergic lidar and sun-photometer measurements

International audienceWe propose a method of retrieving basic information on mineral dust aerosol particles from synergic sun-photometer and multi-wavelength lidar measurements as well as from the observations of lidar light depolarisation. We use this method in a case study of mineral dust episode in Central Europe. Lidar signals are inversed with a modified Klett-Fernald algorithm. Aerosol optical depth measured with the sun-photometer allows to reduce uncertainties in the inversion procedure through which we estimate vertical profile of aerosol extinction. Next we assume that aerosol particles may be represented by ensemble of randomly oriented, identical spheroids. Having calculated vertical profiles of aerosol extinction coefficients for lidar wavelengths, we compute the profiles of local Angstrom exponent. We use laser beam depolarisation together with the calculated Angstrom exponents to estimate the shapes (aspect ratios) and sizes of the spheroids. Numerical calculations are performed with the transition matrix (T-matrix) algorithm by M. Mishchenko. The proposed method was first used during SAWA measurement campaign in Warsaw, spring 2005, to characterise the particles of desert dust, drifting over Poland with a southern-eastern wind (13?14 April). Observations and T-matrix calculations show that mode radii of spheroids representative for desert aerosols' particles are in the range of 0.15?0.3 ?m, while their aspect ratios are lower than 0.7 or larger than 1.7

A calibration method for broad-bandwidth cavity enhanced absorption spectroscopy performed with supercontinuum radiation

An efficient calibration method has been developed for broad-bandwidth cavity enhanced absorption spectroscopy. The calibration is performed using phase shift cavity ring-down spectroscopy, which is conveniently implemented through use of an acousto-optic tunable filter (AOTF). The AOTF permits a narrowband portion of the SC spectrum to be scanned over the full high-reflectivity bandwidth of the cavity mirrors. After calibration the AOTF is switched off and broad-bandwidth CEAS can be performed with the same light source without any loss of alignment to the set-up. We demonstrate the merits of the method by probing transitions of oxygen molecules O-2 and collisional pairs of oxygen molecules (O-2)(2) in the visible spectral range

Multijoule scaling of laser-induced condensation in air

Using 100 TW laser pulses, we demonstrate that laser-induced nanometric particle generation in air increases much faster than the beam-averaged incident intensity. This increase is due to a contribution from the photon bath, which adds up with the previously identified one from the filaments and becomes dominant above 550 GW/cm2. It appears related to ozone formation via multiphotondissociation of the oxygen molecules and demonstrates the critical need for further increasing the laser energy in view of macroscopic effects in laser-induced condensation

Change in Biased Thinking in a Treatment Based on the Motive-Oriented Therapeutic Relationship for Borderline Personality Disorder.

Biased thinking is a common feature of patients presenting with borderline personality disorder (BPD). For the treatment of BPD, it was shown that the individualizing of the treatment, by using the motive-oriented therapeutic relationship (MOTR), had a beneficial short-term effect on process and outcome. So far, it remains unclear what the role of early change in biased thinking is in these treatments. The present study aims to assess whether there is a link between the MOTR, change in biased thinking, and outcome. The sample (N = 60) is based on a randomized controlled trial with two conditions: (a) 30 patients in a 10-session version of psychiatric management, and (b) 30 patients in a 10-session version of psychiatric management augmented with the MOTR. For each patient, three sessions (intake, middle, late) were selected, transcribed, and rated using the Cognitive Errors Rating Scale (CERS). An overall decrease of negative cognitive errors during 10 sessions of treatment was observed, independently of the treatment condition. No specific effect related to change in biased thinking may be attributed to the individualizing of the treatment. These results are discussed with regard to mechanisms of change in treatments for BPD, in particular with regard to the central role that biased thinking, as well as the MOTR, might play early in treatment

Observation of ozone concentration during the solar eclipse

Abstract We report the results of measurements of ozone concentrations during the solar eclipse of 11 Ž . August 1999. The experiment was performed in Warsaw Poland and its surroundings. The temporal evolution of ozone concentration was measured using the differential absorption lidar Ž . DIAL and it was compared with results obtained by several monitoring stations measuring with other methods. In almost all cases, a drop in the ozone concentration was observed during the eclipse. Experimental data was compared with calculations done using a simple model based on NO -O chemical kinetics. q 2001 Elsevier Science B.V. All rights reserved

Saturation of the filament density of ultrashort intense laser pulses in air

We experimentally and numerically characterize multiple filamentation of laser pulses with incident intensities of a few TW/cm2. Propagating 100TW laser pulses over 42m in air, we observe a new propagation regime where the filament density saturates. As also evidenced by numerical simulations in the same intensity range, the total number of filaments is governed by geometric constraints and mutual interactions among filaments rather than by the available power in the bea

Progress towards lightning control using lasers

Lightning research needs on-demand lightning strikes, because of the random character of natural lightning. Lasers have been proposed as alternatives to the current technique using rocket-pulled wires, because they would expectedly provide more flexibility. However, high-energy, nanosecond lasers cannot provide long connected plasma channels. In contrast, we recently reported the triggering of electric events in thunderclouds using ultrashort laser pulses. Further improvements of the laser pulse sequence and experiment geometry are discussed

Identification, frequency, activation and function of CD4+ CD25highFoxP3+ regulatory T cells in children with juvenile idiopathic arthritis

The aim of the study was to test the frequency of CD4+ CD25highFoxP3 regulatory T cells in JIA patients and to assess their activation status and functional activity. The study involved 12 children with JIA and 35 healthy control subjects. PBMC were stained with monoclonal antibodies (anti-CD25, anti-CD4, anti-CD127, anti-CD69, anti-CD71, and anti-FoxP3). The samples were evaluated using flow cytometer. CD4+ CD25− and CD4+ CD25+ cells were isolated by negative and positive selection with magnetic microbeads. CD4+ CD25+ and CD4+ CD25− cells were cultured separately and co-cultured (1:1) with or without PHA. The percentage of Tregs in JIA patients was significantly decreased in comparison with controls (median, 3.2 vs. 4.6; P = 0.042). Relative fluorescence intensities of FoxP3 were higher in JIA patients than in controls (median, 9.1 vs. 6.8). The percentage of activated Tregs (CD71+) was significantly higher in JIA patients in comparison with controls (median, 6.5 vs. 2.8; P = 0.00043). CD4+ CD25+ cells derived from JIA patients and controls were anergic upon PHA stimulation, while CD4+ CD25− cells showed intensive proliferative response. The proliferation rate of CD4+ CD25− cells stimulated by PHA was decreased in co-cultures. In JIA patients, the inhibition of proliferation of CD4+ CD25− cells by CD4+ CD25+ cells was 37.9%, whereas in controls it was significantly lower (55.7%, P = 0.046). JIA patients had statistically lower percentage of Tregs in peripheral blood compared to controls. CD4+ CD25+ cells sorted from peripheral blood of JIA patients had statistically lower ability to suppress CD4+ CD25− cell proliferation in comparison with cells obtained from controls