Exploring statistical and machine learning techniques to identify factors influencing indoor radon concentration.

Radon is a radioactive gas with a carcinogenic effect. The malign effect on human health is, however, mostly influenced by the level of exposure. Dangerous exposure occurs predominantly indoors where the level of indoor radon concentration (IRC) is, in its turn, influenced by several factors. The current study aims to investigate the combined effects of geology, pedology, and house characteristics on the IRC based on 3132 passive radon measurements conducted in Romania. Several techniques for evaluating the impact of predictors on the dependent variable were used, from univariate statistics to artificial neural network and random forest regressor (RFR). The RFR model outperformed the other investigated models in terms of R2 (0.14) and RMSE (0.83) for the radon concentration, as a dependent continuous variable. Using IRC discretized into two classes, based on the median (115 Bq/m3), an AUC-ROC value of 0.61 was obtained for logistic regression and 0.62 for the random forest classifier. The presence of cellar beneath the investigated room, the construction period, the height above the sea level or the floor type are the main predictors determined by the models used.

The FIRST large-scale mapping of radon concentration in soil gas and water in Romania.

In the framework of the last Council Directive 2013/59 (Euratom, 2014) laying down basic safety standards for protection against the dangers arising from exposure to ionizing radiation, the problem of radon was assumed in Romania at national level by responsible authorities through the design and development of a National Radon Action Plan and an adequate legislation (HG nr. 526/2018). In order to identify radon risk areas, however, it is necessary to perform systematic radon measurements in different environmental media (soil gas, water, indoor air) and to map the results. This paper presents an atlas of up-to-date radon in soil and water levels for central and western part of Romania. The radon in soil map includes data from 2564 measurements carried out on-site, using Luk3C radon detector. The Luk-VR system was used to measure radon activity concentration from 2452 samples of drinking water. The average radon activity concentration was 29.3 kBq m-3 for soil gas, respectively 9.8 Bq l-1 for water dissolved air. Mapping of radon can be a useful tool to implement radon policies at both the national and local levels, defining priority areas for further study when land-use decisions must be made.

Photodynamic effect on cancer cells influenced by electromagnetic fields.

The synergism of low-frequency electromagnetic field treatment and photodynamic effect on killing of human cancer cells is presented. The weak pulsating electromagnetic field (PEMF) generated by Helmholtz coils in the mT range influences the permeability of cell membranes for photosensitizers. Several types of sensitizers were excited by visible light during incorporation without and with two kinds of PEMF treatment. In the first part suitable photosensitizers were selected in the absorption range between 400 and 700 nm against human myeloid leukaemia K562 and human histiocytic lymphoma U937 cells by treatment of PEMF consisting of rectangular pulse groups. In the second part amplitude and frequency dependencies were measured using sinuous PEMF and white light with the result that after 12 min the PEMF treatment enhanced photodynamic effectivity by more than 40% over the control value. Taking into account the influence of many parameters, an additional optimization will be possible by photodynamic PEMF synergism for an increased drug delivery in general.

[The celiac syndrome. The clinico-histological correlations]. / Sindromul celiac. Corelatii clinico-histologice.

The authors studied a number of 445 children with malabsorption in which a jejunal biopsy was done. Concerning the celiac disease, they emphasized the value of jejunal biopsy in diagnosis and monitoring the treatment.

[The late results after mobilizing bone resections in posttraumatic rigidity of the elbow]. / Rezultate la distanta dupa rezectiile osoase mobilizatoare în redorile posttraumatice ale cotului.

Two categories of posttraumatic rigidities are distinguished: partial and total. The severity of partial rigidities depends on the residual flexion-extension amplitude arch and they are divided accordingly into functional rigidities, with a residual amplitude arch of 60-100 degrees, and non-functional ones, with residual flexion amplitude arches of 0-80 degrees or over 100 degrees. The severity of total rigidities depends mainly on the preservation or loss of the pronation-supination movement. To the department where the authors are working were admitted during 16 years (1970-1986), 54 cases of posttraumatic rigidities of the elbow, on which 63 operations were performed. The surgical indications were established according to the anatomopathological type of lesions, to the time elapsed from the accident, to the age and occupation of the patient and to the residual amplitude arches. The late results were checked up after 1-10 years, on the average after 3-4 years, by comparison of pre- and postoperative Rocher indices. The flexion-extension movements benefitted postoperatively by 70% in total rigidities and by 45% in the partial ones and the pronation-supination movements, by 40%. The results regarding the change of the biomechanical functionality conditions following the mobilizing bone resections are shown in comparison with those obtained by arthrosis and total elbow prostheses.

[Long-term results of mobilization by bone resection in patients with post-traumatic total stiffness and ankylosis of the elbow. Study and results of 39 operations]. / Résultats éloignés des résections osseuses mobilisatrices des raideurs totales et ankyloses post-traumatiques du coude. Etude et résultats de 39 opérations.

Thirty patients with post-traumatic stiffness and ankylosis of the elbow were treated operatively at the Colentina Clinical Hospital, from 1970-1986. They were treated by 39 surgical mobilisation using Ollier technique. In eleven patients with a persisting functional amplitude of the prono-supination, the resections have been effected on the distal end of the humerus and on the olecranon, and in nineteen with a limited prono-supination too, it was added a resection of the radial head. The mobilisations were realised without interposition. At follow-up the patients were evaluated after 1 to 8 years, using the pre- and post- operative Rocher's indices and the Kerboull's classification. The flexion-extension was improved by 55 per cent, the pronation by 55.3 per cent and the supination also with 55.3 per cent. The results plead for the maintaining of this type of surgical treatment for the treatment of post-traumatic stiffnesses and ankyloses of the elbow, though there are not complete satisfactory, especially for the joint stability.

[Condensing osteitis of the middle third of the clavicle]. / Osteita condensanta a tremii mediale a claviculei.

A total of 16 cases only have been reported in the world specialized literature. This is a new case, of a patient aged 20 years, a male working in the metallurgical industry. This is the first case reported in our country. Clinically the patient presented a painful global swelling of the median third of the clavicula on the left side. Biological constant were normal. Radiographic investigations revealed an increase in volume and a condensation of the median part of the clavicula, and scintigraphical studies revealed an intense incorporation of the radioisotope. Histopathologic studies showed lamellar and spongious bone tissue, with a normal trabecular structure, although considerably thickened. Data for the differential diagnosis are presented, and in the first place those concerning intra-sterno-clavicular hyperostosis, sterno-costo-clavicular arthrosis, chronic subacute osteitis, avascular necrosis of the clavicular epiphysis (Friedrich disease), and Tietze syndrome. The etiopathogenesis of this rare benign clinico-radiologic entity remains unknown.

[Intra-articular teratoma of the knee]. / Teratom intraarticular al genunchiului.

An unique case is presented, never mentioned before the world specialized literature, concerning an intraarticular teratoid formation in the knee. Initially a sessile, pediculated formation 3/3 cm in size, on the interior aspect of the synovial sac, became free following an accident, and blocked the knee in the flexed position at an angle of 30 degrees, simulating rupture of the medial meniscus and intercondylar luxation.

A simple technique for arthrodesis of the ankle.

We report the results of a simple technique of ankle arthrodesis which is, however, indicated only when the foot can be reduced manually to a functional position. A special milling-cutter with an expulsion piston is used to obtain a cylindrical bone graft which is reintroduced having been reversed from left to right and rotated through 90 degrees. The operation is simple and very rapid. It has been performed on 72 patients, 62 of whom have been followed up for an average of six years. Fifty-seven were painless with bony fusion in a functional position; one was solid and painless but in valgus. In only four patients were the results unsatisfactory.

[Idiopathic recurrent proximal tibiofibular dislocation in adults. 3 cases treated by an original surgical technic]. / La luxation récidivante idiopathique tibio-péronière proximale chez l'adulte. Trois cas traités par une technique opératoire originale.

Three cases of recurrent dislocation of the proximal end of the fibula were seen and treated by an original technique combining a fibulo-tibial screw and the creation of a pseudarthrosis at the upper end of the fibula shaft. The results were satisfactory. The authors have made a review of the literature and found seventeen comparable cases, ten in children and seven in adults. The authors describe the complications which may follow a tibio fibular arthrodesis or resection of the proximal end of the fibula.