133 research outputs found

    GPGPU Computing for Microscopic Simulations of Crowd Dynamics

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    We compare GPGPU implementations of two popular models of crowd dynamics. Specifically, we consider a continuous social force model, based on differential equations (molecular dynamics) and a discrete social distances model based on non-homogeneous cellular automata. For comparative purposes both models have been implemented in two versions: on the one hand using GPGPU technology, on the other hand using CPU only. We compare some significant characteristics of each model, for example: performance, memory consumption and issues of visualization. We also propose and test some possibilities for tuning the proposed algorithms for efficient GPU computations

    On a risk of inhalation exposure during visits in Chernobyl exclusion zone

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    In recent years Chernobyl exclusion zone has become a very popular tourist destination. Many people visiting power plant, Pripyat city or surrounding villages use different types of personal dosimeters to control external exposure, however very small group of tourist have opportunity to control internal contamination of respiratory tract using dedicated, high sensitive whole body counters. In this study 11 anti-dust masks collected from CEZ visitors and filters from one military MP-5 mask were analyzed using alpha, beta and gamma spectrometry to determine doses from actinides and fission products which can be inhaled without proper protective equipment. Results showed, that average effective dose from inhalation of contaminated aerosol in case of single-day trip (avoided due to use of mask) was 1.3 μSv per person, which is much smaller than potential effective dose after exploration of highly contaminated areas like Jupiter complex, where combined dose from all measured nuclides collected on MP-5 mask filter was 1.4 mSv

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

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    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

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    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

    Zofia Sokolewicz (1932 - 2020)

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    Wspomnienia przyjaciów, współpracowników i uczniów o śp. prof. Zofii Sokolewicz

    Influence of inhaler and fine particle on efficacy of inhalation therapy in COPD

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    Farmakoterapia stosowana drogą inhalacyjną wykorzystuje efekt podania leku bezpośrednio do narządu docelowego. Umożliwia to podanie bardzo małej dawki leku, która wywiera efekt kliniczny porównywalny z terapią doustną przy wielokrotnie mniejszym efekcie toksycznym. Niemniej, także w terapii inhalacyjnej istnieją czynniki ograniczające dostęp molekuł leku do receptorów narządów docelowych. Dostarczenie pożądanej dawki leku z inhalatora do płuc zależy od typu inhalatora (ciśnieniowy, proszkowy), jego charakterystyki (opór wewnętrzny, średnica cząstek i dystrybucja ich poszczególnych frakcji w generowanym aerozolu), warunków termicznych powietrza oraz od zdolności inhalacyjnych samego chorego. Zastosowanie inhalatorów suchego proszku (DPI) dzięki uwalnianiu dawki leku wdechem wyeliminowało występujący u wielu chorych problem koordynacji wdechu z momentem uwolnienia aerozolu z inhalatora. Poszczególne inhalatory DPI różnią się jednak istotnie pod względem możliwości ich optymalnego stosowania przez chorych na obturacyjne choroby układu oddechowego. Z tego powodu powinny być z rozwagą dobierane do potrzeb i możliwości każdego chorego.Orally inhaled products delivered via inhalation exert their effect directly to the target organ. This allows to administer a very low dose of a drug compared with an oral route with similar clinical effect and significantly reduced toxicity. However inhalation therapy is also limited by several factors. Delivery of the desired dose of the drug to the airways depends on a type of the inhaler — pressurised metered-dose inhaler (pMDI) or dry powder inhaler (DPI), inhaler characteristics (low or high internal resistance, diameter of particles and distribution of the generated aerosol fine particles), thermal conditions of air, and ability of patient to generate sufficient inspiratory flow (for DPI) or to coordinate actuation with inhalation (for pMDI). Unlike pMDIs, DPIs are breath- -actuated, hence avoiding the need for the patient to coordinate actuation with inspiration. Furthermore, DPIs are propellant-free and do not produce the cold sensation on inhalation. Currently available DPIs vary widely in design, operating characteristics and performance. And poor inhalation technique may compromise treatment efficacy. Hence, there is a clear need for a careful selection of DPIs for different patient groups, including children, elderly patients and those with severe airway obstruction

    hCG-secreting malignancies – diagnostic pitfalls

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    We present a case of a 34-year-old male patient referred to our Uro-oncology Department with a suspicion of a metastatic germ cell tumour, owing to enlarged left testicle and elevated b-hCG concentration (39 mIU/mL). Impaired performance status caused by extensive pulmonary and liver metastases, accompanied by significant lymphadenopathy, necessitated prompt management. However, a testicular tumour was excluded on ultrasound imaging; a hydrocele only was found. The b-hCG concentration was not increasing (37 mIU/mL). We found a diagnosis of an extragonadal germ cell tumour doubtful, and a liver biopsy was performed. Due to the patient’s quick deterioration, we decided to commence pre-phase chemotherapy with cisplatin and etoposide, which resulted in a significant clinical improvement. The pathological examination, along with immunoassays, revealed undifferentiated cholangiocarcinoma, and the patient continued chemotherapy with a biliary tract cancer regimen, i.e. cisplatin and gemcitabine. Unfortunately, the clinical response was short-lived; the disease progressed, the patient was offered best supportive care and died two months after the diagnosis. The case underpins the literature review with respect to differential diagnosis of an elevated hCG concentration. In particular, we discuss ectopic secretion in non-trophoblastic and non-germinal malignancies and the causes of false positive assays.We present a case of a 34-year-old male patient referred to our Uro-oncology Department with a suspicion of a metastatic germ cell tumour, owing to enlarged left testicle and elevated β-hCG concentration (39 mIU/ml). Impaired performance status caused by extensive pulmonary and liver metastases, accompanied by significant lymphadenopathy, necessitated prompt management. However, a testicular tumour was excluded by ultrasound examination; a hydrocele only was found. The β-hCG concentration was not increasing (37 mIU/ml). We found a diagnosis  of an extragonadal germ cell tumour doubtful, and a liver biopsy was performed.  Due to the patient’s quick deterioration, we decided to commence pre-phase chemotherapy with cisplatin and etoposide, which resulted in a significant clinical improvement. The pathological examination, along with immunoassays, revealed undifferentiated cholangiocarcinoma, and the patient continued chemotherapy  with a biliary tract cancer regimen, i.e. cisplatin and gemcitabine. Unfortunately, the clinical response was short-lived; the disease progressed, the patient was offered best supportive care and died two months after the diagnosis. The case underpins the literature review with respect to differential diagnosis  of an elevated hCG concentration. In particular, we discuss ectopic secretion  in non-trophoblastic and non-germinal malignancies and the causes of false positive assays

    OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge

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    We use the extended and updated Optical Gravitational Lensing Experiment (OGLE) Collection of Variable Stars to thoroughly analyze the distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive the absolute Wesenheit magnitude and individual distance of each RR Lyrae star. We confirm results from our earlier study showing that RR Lyrae stars are present in between the Magellanic Clouds, though their three-dimensional distribution more resembles two extended overlapping structures than a strict bridge-like connection. The contours do connect in the southern parts of the Bridge, albeit on a level too low to state that an evident connection exists. To test the sample numerically, we use multi-Gaussian fitting and conclude that there is no additional population or overdensity located in the Bridge. We also try to reproduce results on the putative RR Lyrae Magellanic Bridge stream by selecting RR Lyrae candidates from Gaia Data Release 1. We show that we are not able to obtain the evident connection of the Clouds without many spurious sources in the sample, as the cuts are not able to remove artifacts without eliminating the evident connection at the same time. Moreover, for the first time, we present the Gaia Data Release 2 RR Lyrae stars in the Magellanic Bridge area and show that their distribution matches our results

    OGLE-ing the Magellanic System: RR Lyrae Stars in the Bridge

    Get PDF
    We use the extended and updated Optical Gravitational Lensing Experiment (OGLE) Collection of Variable Stars to thoroughly analyze the distribution of RR Lyrae stars in the Magellanic Bridge. We use photometric metallicities to derive the absolute Wesenheit magnitude and individual distance of each RR Lyrae star. We confirm results from our earlier study showing that RR Lyrae stars are present in between the Magellanic Clouds, though their three-dimensional distribution more resembles two extended overlapping structures than a strict bridge-like connection. The contours do connect in the southern parts of the Bridge, albeit on a level too low to state that an evident connection exists. To test the sample numerically, we use multi-Gaussian fitting and conclude that there is no additional population or overdensity located in the Bridge. We also try to reproduce results on the putative RR Lyrae Magellanic Bridge stream by selecting RR Lyrae candidates from Gaia Data Release 1. We show that we are not able to obtain the evident connection of the Clouds without many spurious sources in the sample, as the cuts are not able to remove artifacts without eliminating the evident connection at the same time. Moreover, for the first time, we present the Gaia Data Release 2 RR Lyrae stars in the Magellanic Bridge area and show that their distribution matches our results
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