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]

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.

[Osseous desmoid fibroma (2 case reports)]

Bone dermoid fibroma, described by Jaffe in 1958 is a benign fibroblastic tumour characterized by a remarkable tendency to expansion and to local recidives, without metastasizing. Some 38 cases have been reported to the present in the specialized literature. Two new cases are reported now, the first in the Romanian medical literature, one with localization of the tumour in the superior tibioperoneal metaphysis, and another located in the inferior femoral metaphysis. The first case recidivated after 3 surgical exereses over a period of nearly two years, and had to be amputated. The second case was solved by resection-arthrodesis of the Juvara-Merle d'Aubigne type, and is currently followed-up.

[Treatment of chronic post-traumatic infections of the locomotor apparatus with methyl-polymethacrylate pearls containing gentamicin]

A new efficient method is presented based on the surgical cure of the infectious focus and the introductions of strings of methyl-polimetacrylate beads containing gentamycin. The method was demonstrated to be far superior when compared with both general antibiotherapy, and local antibiotherapy with antibiotic powder or with instillations of antibiotic solutions. The failures of this new treatment represented only 24.5% of all cases. The presence of gentamycin-containing beads in the infection focus provides constant and prolonged delivery of the antibiotic in highly bactericidal concentration.

[Achilles tendoplasty (original technic and results)]

The technique consists in an intra-tendinous suture with two thick cotton strands, and in surrounding these strands with the tendon of the small plantar muscle. The entire assembly is coated with a square tendinous flap obtained from the tendinomuscular junction and sutured to itself just like a muff. From the first application of the technique in 1960 to the present a total of 38 cases have been solved, of which 29 have been followed at intervals between 2 and 19 years. The good results that have been obtained justify the interest of the technique. A series of considerations are made on the biomechanisms that induce the lesion, on the macroscopic aspects, and on the microscopic and microangiographic ones.

[Rapid arthrodesis of the ankle by verticalization of the articular interline, using a cylindrical piston drill (original surgical technic. Results)]

An original technique is presented for tibio-tarsal arthrodesis, that can be achieved in 8--10 minutes with the aid of a cylindrical bore equipped with an expulsion piston, under Rx-TV control. Since 1974 a total of 22 patients have been operated and 21 remarkably good results were obtained, evaluated both clinically and radiologically. The technique is indicated in posttraumatic arthrodeses or after inflammatory affections of the ankle and in paralytic affections of the foot, when there are severe displacements in the foot-leg axis.

[Lumbrical plus syndrome]

A rare case of paradoxical extension of the medius finger - the so-called lumbrical plus finger syndrome-is described. At operation was found a fibrous adherence of the third lumbrical at the sheath of the flexor digitorum profundus. Some of pathological mechanisms are discussed. A satisfactory result was obtained after the resection of the tendon of the second lumbrical.