Enhanced production of low-mass electron-positron pairs in 40-AGeV Pb-Au collisions at the CERN SPS

We report on first measurements of low-mass electron-positron pairs in Pb-Au collisions at the CERN SPS beam energy of 40 AGeV. The observed pair yield integrated over the range of invariant masses 0.2<m</=1 GeV/c(2) is enhanced over the expectation from neutral meson decays by a factor of 5.9+/-1.5(stat)+/-1.2(syst data)+/-1.8(syst meson decays), somewhat larger than previously observed at the higher energy of 158 AGeV. The results are discussed with reference to model calculations based on pi(+)pi(-)-->e(+)e(-) annihilation with a modified rho propagator. They may be linked to chiral symmetry restoration and support the notion that the in-medium modifications of the rho are more driven by baryon density than by temperature.

[The CO2 laser in dermatotherapy--use and indications]

Due to the high absorption of infrared light in water the CO2 laser (lambda = 10,600 nm) is suitable for cutting and vaporizing tissue. The ablation of pathological tissue by means of the CO2 laser can be exactly controlled. The treated area is usually dry and clear since blood and lymph vessels up to a diameter of 1 mm are sealed. Postoperative swelling and pain are reduced compared with electrosurgery. Important and frequent indications for CO2 laser application are HPV papillomas (condylomata acuminata, common warts, bowenoid papules) and the removal of tattoos. The CO2 laser is also suitable for the removal of benign and disseminated lesions such as angiofibromas, syringomas, trichoepitheliomas, epidermal nevi etc. Lesions of the oral mucosa (leukoplakias, mucosal warts) can be removed by means of the CO2 laser. Additionally, the treatment of vascular lesions (nevi flammei, lymphangiomas, telangiectasias) has been described, although the CO2 laser does not operate in a vessel-specific manner. As this review article demonstrates, the CO2 laser has a broad range of applications and represents an enrichment of dermatotherapy.

[Treatment of naevi flammei with the argon laser]

We report on 901 patients with port wine stains treated by means of an argon laser. The treatment results have been definitively evaluated in 371 patients. They were significantly influenced by the patients' age and by the colour of the lesions. The worst response to the therapy was seen in pink port wine stains in children and juvenile patients (20% good results), in contrast to red and purple lesions in adult patients (80% excellent and good results). The size of the port wine stains did not significantly influence the treatment results, but in extensive lesions homogeneous lightening could not usually be attained and treatment often extended over some years. Port wine stains in the head and neck area responded best to therapy, and lesions on the legs, worst. Altogether, in 60%-70% of adult patients excellent or good results were obtained, the lesions being completely removed or significantly lightened and reduced in size. The side-effects of laser therapy were scar formation (7.3%) and changes in pigmentation (8.6%).