Production of magnesium-aluminium bimetallic bars using the explosive cladding method

The paper presents the results of the preparation of semi-finished products in the form of magnesium-aluminium round bimetallic bars by the explosive cladding method. The system of samples consisted of an aluminium tube (1050 grade) and magnesium bar (grade AZ31) was prepared. The analysis of microstructure and mechanical tests of the joint quality was carried out. On the base of obtained results it was found that the explosive cladding parameters used to obtain the semi-finished bimetallic product characterized by a slight ovality and mechanical connection of the individual layers were correct

131I thyroid activity and committed dose assessment among family members of patients treated with radioactive iodine

The main goal of the present study was estimation of an internal contamination of 131I among family members of patients treated with radioactive iodine. Thyroid activity measurements of 131I in examined volunteers were performed using a whole-body spectrometer at the institute of nuclear physics, Polish academy of sciences. During this research, 20 relatives of patients treated with 131I were examined: eight women and 12 men with an age in the range from 3 to 72 years. In the case of nine individuals, the activity of 131I in the thyroid was below the detection limit, but among the remaining 11 individuals, the activity varied from (9 ± 3) Bq up to (1140 ± 295) Bq. Subsequently, based on the measurements of thyroid 131I activities, the corresponding doses were assessed. The highest estimated effective dose reached 218 μSv, while the thyroid equivalent dose was 2.4 mSv. In addition, the experimental data obtained were statistically analysed together with the results of surveys of the individuals participating in the study by means of correspondence analysis and nonparametric tests: Mann–Whitney, gamma, χ2 and Yule Phi coefficient. These analyses revealed relationships between 131I activities in the thyroids of the examined individuals and their housing conditions as well as consumption of meals prepared by the patients

Measurement of 131I activity in thyroid of nuclear medical staff and internal dose assessment in a Polish nuclear medical hospital

This paper presents results of 131I thyroid activity measurements in 30 members of the nuclear medicine personnel of the Department of Endocrinology and Nuclear Medicine Holy Cross Cancer Centre in Kielce, Poland. A whole-body spectrometer equipped with two semiconductor gamma radiation detectors served as the basic research instrument. In ten out of 30 examined staff members, the determined 131I activity was found to be above the detection limit (DL = 5 Bq of 131I in the thyroid). The measured activities ranged from (5 ± 2) Bq to (217 ± 56) Bq. The highest activities in thyroids were detected for technical and cleaning personnel, whereas the lowest values were recorded for medical doctors. Having measured the activities, an attempt has been made to estimate the corresponding annual effective doses, which were found to range from 0.02 to 0.8 mSv. The highest annual equivalent doses have been found for thyroid, ranging from 0.4 to 15.4 mSv, detected for a cleaner and a technician, respectively. The maximum estimated effective dose corresponds to 32% of the annual background dose in Poland, and to circa 4% of the annual limit for the effective dose due to occupational exposure of 20 mSv per year, which is in compliance with the value recommended by the International Commission on Radiological Protection

Genetic Polymorphism in Evolving Population

We present a model for evolving population which maintains genetic polymorphism. By introducing random mutation in the model population at a constant rate, we observe that the population does not become extinct but survives, keeping diversity in the gene pool under abrupt environmental changes. The model provides reasonable estimates for the proportions of polymorphic and heterozygous loci and for the mutation rate, as observed in nature

A gravitationally lensed quasar discovered in OGLE

Indexación: Scopus; Web of Science.We report the discovery of a new gravitationally lensed quasar (double) from the Optical Gravitational Lensing Experiment (OGLE) identified inside the ~670deg2 area encompassing the Magellanic Clouds. The source was selected as one of ~60 'red W1-W2' mid-infrared objects from WISE and having a significant amount of variability in OGLE for both two (or more) nearby sources. This is the first detection of a gravitational lens, where the discovery is made 'the other way around', meaning we first measured the time delay between the two lensed quasar images of -132 < tAB < -76 d (90 per cent CL), with the median tAB ~-102 d (in the observer frame), and where the fainter image B lags image A. The system consists of the two quasar images separated by 1.5 arcsec on the sky, with I ~20.0mag and I ~19.6mag, respectively, and a lensing galaxy that becomes detectable as I ~21.5 mag source, 1.0 arcsec from image A, after subtracting the two lensed images. Both quasar images show clear AGN broad emission lines at z=2.16 in the New Technology Telescope spectra. The spectral energy distribution (SED) fitting with the fixed source redshift provided the estimate of the lensing galaxy redshift of z ~0.9 ± 0.2 (90 per cent CL), while its type is more likely to be elliptical (the SED-inferred and lens-model stellar mass is more likely present in ellipticals) than spiral (preferred redshift by the lens model). © 2018 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.https://academic.oup.com/mnras/article/476/1/663/483368

Simulated ecology-driven sympatric speciation

We introduce a multi-locus genetically acquired phenotype, submitted to mutations and with selective value, in an age-structured model for biological aging. This phenotype describes a single-trait effect of the environment on an individual, and we study the resulting distribution of this trait among the population. In particular, our simulations show that the appearance of a double phenotypic attractor in the ecology induces the emergence of a stable polymorphism, as observed in the Galapagos finches. In the presence of this polymorphism, the simulations generate short-term speciation, when mating preferences are also allowed to suffer mutations and acquire selective value.Comment: 11 pages, 5 figures, 1 table, uses package RevTe

71. The results of postoperative radiotherapy in 63 patients with low-grade gliomas treated in Greatpoland Cancer Center

IntroductionLow-grade glicomas represents 15% of all primary brain tumors.Material and MethodBetween 1990–97 63 patient with low-grade gliomas were treated in Greatpoland Cancer Center (39 males, 24 females; age between 20–60 year). 15 patients had andegrone complete surgical excision, 48 partial or subtotal excision of tumor. The frontal lobe was affected in 33 patients, the temporal lobe in 14 patients. Patients received conventional irradiaton of 60 Gy.Results*Five patients with histologically verified pilocytic astrocytomas(I) were treated after partial excision, median of age 29.2 year median survival 58 months (27–108). Only one patient died 27 months after radiotherapy. *Thirteen patients with fibrylar astrocytomas(II)-11 post subtotal excision-median age 37.7 year median survival 32.5 months. Recurrent tumor in two patients. Five patients are alive. *Ten patients with protoplasmatic astrocytoma(II)-7 post subtotal excision median of age 43.5 year median survival 30.8 months. Four patients alive. *Seven patients with gemistocytic astrocytomas(II) (6 post subtotal excision)-median age 36 year, median survival 32 months. Only one patient alive. *Eleven patients with oligoastrocytomas(II)-11 post subtotal excision, median age 38.6 year, median survival 43.9 months. Two patients with recrrent tumor. Alive 8 patients. *Seventeen patients with oligodendrogliomas (11 post subtotal excision) median age 39 years, median survival 39 months. One patien with recrrent tumor. Alive 8 patients.Conclusions*30 patients are alive(48%); *histopathologic diagnosis pilocytic astrocytomas asociated with age 10 years younger then either low-grade gliomas and long-term survivors; *poor prognistic factor in gemistocytic astrocytomas-only one patient alive; *five patients with recurrent tumor among 17 to 49 months after radiotheraphy

Gravitational Microlensing Events from the First Year of the Northern Galactic Plane Survey by the Zwicky Transient Facility

The Zwicky Transient Facility (ZTF) (Bellm et al. 2019; Graham et al. 2019; Masci et al. 2019) is currently surveying the entire northern sky, including dense Galactic plane fields. Here, we present preliminary results of the search for gravitational microlensing events in the ZTF data collected from the beginning of the survey (2018 March 20) through 2019 June 30

OGLE16aaa - a Signature of a Hungry Super Massive Black Hole

We present the discovery and first three months of follow-up observations of a currently on-going unusual transient detected by the OGLE-IV survey, located in the centre of a galaxy at redshift z=0.1655. The long rise to absolute magnitude of -20.5 mag, slow decline, very broad He and H spectral features make OGLE16aaa similar to other optical/UV Tidal Disruption Events (TDEs). Weak narrow emission lines in the spectrum and archival photometric observations suggest the host galaxy is a weak-line Active Galactic Nucleus (AGN), which has been accreting at higher rate in the past. OGLE16aaa, along with SDSS J0748, seems to form a sub-class of TDEs by weakly or recently active super-massive black holes (SMBHs). This class might bridge the TDEs by quiescent SMBHs and flares observed as "changing-look QSOs", if we interpret the latter as TDEs. If this picture is true, the previously applied requirement for identifying a flare as a TDE that it had to come from an inactive nucleus, could be leading to observational bias in TDE selection, thus affecting TDE-rate estimations.Comment: Accepted in MNRAS Letter

Cataclysmic Variables in the First Year of the Zwicky Transient Facility

Using selection criteria based on amplitude, time, and color, we have identified 329 objects as known or candidate cataclysmic variables (CVs) during the first year of testing and operation of the Zwicky Transient Facility. Of these, 90 are previously confirmed CVs, 218 are strong candidates based on the shape and color of their light curves obtained during 3–562 days of observation, and the remaining 21 are possible CVs but with too few data points to be listed as good candidates. Almost half of the strong candidates are within 10 deg of the galactic plane, in contrast to most other large surveys that have avoided crowded fields. The available Gaia parallaxes are consistent with sampling the low mass transfer CVs, as predicted by population models. Our follow-up spectra have confirmed Balmer/helium emission lines in 27 objects, with four showing high-excitation He ii emission, including candidates for an AM CVn, a polar, and an intermediate polar. Our results demonstrate that a complete survey of the Galactic plane is needed to accomplish an accurate determination of the number of CVs existing in the Milky Way