Thermal model development for a CubeSat

CubeSats provide a cost-effective means of several functions of satellites due to their small size, mass, relative simplicity and short development time. Therefore, CubeSat technologies have been widely studied and developed by space organizations, companies and educational institutions all over the world. These satellites have certain drawbacks. Small surface areas are a consequence of their small size which often imply thermal and power constraints. A novel development of CubeSats known as PW-Sat has been developed by Warsaw University of Technology. A control-oriented lumped thermal model of this satellite containing a fuel tank in the form of nonlinear ordinary differential equations is proposed in this paper. The model is able to simulate the thermal behavior of the surface and fuel tank of the satellite in its orbit. For the PW-Sat to operate reliably, the temperature of the fuel tank has to be maintained within given safety limits. Because of the limited power, passive thermal control is assumed in this case. Several simulation results are presented for different surface compositions to determine whether they are able to guarantee the prescribed temperature range throughout the entire orbit or not

25(OH)D Concentration in Neonates, Infants, and Toddlers From Poland—Evaluation of Trends During Years 1981–2011

Introduction: The numerous evidence showing spectrum of vitamin D effects on human health resulted in both updates of vitamin D supplementation guidelines for general population and concerns on potential risk of hypercalcaemia. The aim of this study was to analyse trends in serum 25-hydroxyvitamin D concentration (25(OH)D) change over the 30 years of operation of a single pediatric diagnostic unit.Materials and methods: Calcium-phosphate metabolism markers and 25(OH)D concentrations were analyzed in a group that consisted of newborns and infants commissioned for diagnostics due to suspected calcium-phosphate metabolic disturbances (n = 3,163; mean age 8.0 ± 3.0 months).Results: 25(OH)D < 10 ng/ml was noted in 4.5% of patients (n = 163), 10–20 ng/ml in 14.7% (n = 465), 20–30 ng/ml in 23.9% (n = 756) and 30–50 ng/ml in 35.9% (n = 1,136). The mean 25(OH)D concentration in analyzed group was 37.5 ± 24.5 ng/ml. In patients with 25(OH)D concentration < 10 ng/ml a normal calcaemia (2.25–2.65 mmol/l) was noted in 83.4% cases (n = 136). Eighty one patients had 25(OH)D concentrations above 100 ng/ml with co-existing calcaemia in range of 2.6–4.38 mmol/l (mean Ca = 2.69 mmol/l). Hypocalcaemia (Ca < 2.25 mmol/l) was observed in 0.54%, (n = 17). 13.8% patients revealed calcium levels >2.65 mmol/l (n = 435). In general, the mean calcium-phosphate markers values were within the reference range for age. The highest mean 25(OH)D concentration of 51.8 ng/ml ± 38.8 was noted in years 1981–1999 (n = 305). The lowest mean 25(OH)D value was observed in years 2010–2011 (29.0 ng/ml ± 13.6; n = 412). The trend of decreasing 25(OH)D concentration during analyzed time period was significant (r = −0.29, p < 0.0001).Conclusions: Eighty percentage of children aged 0–36 months had 25(OH)D concentration >20 ng/ml, however, during 3 decades a mean 25(OH)D concentrations trended significantly to decrease. A direct relationship between low 25(OH)D concentration and hypocalcaemia was not observed nor between high 25(OH)D concentration and hypercalcemia

Ocena skuteczności klipsowania tętniaków wewnątrzczaszkowych w terminie odległym za pomocą angiografii tomografii komputerowej

Background and purpose The aim of this retrospective study was to assess the effectiveness of aneurysm clipping by computed tomography angiography (CTA) in a long-term follow-up. Material and methods The CTA examination was performed in 119 patients who had 143 aneurysms clipped. The examinations were performed 3 to 11 years (mean 6 years) after clipping using a GE Lightspeed PRO16 scanner. Results In all cases but one, good quality CTA images, suitable for evaluation of the arteries around the clip site, were obtained. Complete aneurysm closure without neck remnant or regrowth was confirmed in 137 (96%) aneurysms. In 4 (3%) cases, neck remnants were detected (2 on the anterior communicating artery [AComA] and 2 on the middle cerebral artery [MCA]). A total clip slippage from the aneurysm dome was revealed in 1 case. One case of aneurysm re-rupture was noted, 11 years after clipping. The rebleeding was caused by AComA aneurysm regrowth. Among these 6 patients with unsatisfactory clipping, 2 required further treatment and 4 remain under observation. Nineteen ‘de novo’ aneurysms in other locations were found in 14 (12%) patients. Summing up all of the pathological findings in the study group, there were 18 (15%) patients who needed further management including close surveillance or re-treatment. Conclusions Computed tomography angiography is a simple and reliable method of aneurysm clipping evaluation. The long-term follow-up CTA confirmed the permanent and complete obliteration of 96% of the aneurysms. The rate of unsatisfactory aneurysm closure was 4%, but only 1.4% needed re-treatment during a mean follow-up of 6 years. The annual risk of aneurysm re-rupture was 0.1%.Wstęp i cel pracy Celem niniejszej retrospektywnej pracy była ocena skuteczności klipsowania tętniaków wewnątrzczaszkowych w odległym terminie po operacji za pomocą angiografii tomografii komputerowej (angio-TK). Materiał i metody Angio-TK wykonano u 119 pacjentów ze 143 zaklipsowanymi tętniakami. Badania przeprowadzano w ciągu 3–11 lat od operacji (średnio 6 lat) aparatem CT GE Lightspeed PRO16. Wyniki U wszystkich pacjentów, poza jednym, uzyskano obrazy pozwalające na wiarygodną ocenę naczyń w pobliżu założonego klipsa. Spośród 143 zaklipsowanych tętniaków, w 137 (96%) przypadkach stwierdzono prawidłowe zamknięcie, bez cech odtwarzania się ani pozostałości tętniaka. Pozostałość szyi klipsowanego tętniaka (2 na tętnicy łączącej przedniej i 2 na tętnicy mózgu środkowej) stwierdzono w 4 przypadkach. W jednym przypadku uwidoczniono całkowite zsunięcie się klipsa z tętniaka tętnicy łączącej przedniej. W okresie objętym analizą zanotowano jeden przypadek nawrotowego krwotoku podpajęczynówkowego po 11 latach od operacji. Powodem był odrost tętniaka tętnicy łączącej przedniej. Spośród 6 chorych z niezadowalającym zaklipsowaniem, 2 wymagało dalszego leczenia, a 4 – obserwacji. U 14 (12%) pacjentów wykryto 19 tętniaków de novo w innych lokalizacjach, z których 18 nie wymagało leczenia. Biorąc pod uwagę wszystkie nieprawidłowości naczyniowe w badanej grupie, 18 (15%) pacjentów wymagało dalszej obserwacji lub leczenia. Wnioski W ocenie autorów angio-TK jest wygodnym i wiarygodnym sposobem kontroli po operacjach zaklipsowania tętniaka. Odległe badania angio-TK wykazały, że klipsowanie całkowicie i trwale wyłącza z krążenia 96% tętniaków. Odsetek niezadowalającego zaklipsowania wyniósł 4%, ale tylko 1,4% pacjentów wymagało dalszego leczenia w okresie obserwacji wynoszącym średnio 6 lat. Ryzyko ponownego krwotoku z zaklipsowanego tętniaka wyniosło 0,1% na rok

Jakość badań densytometrycznych w Polsce : wyniki oceny wstępnej

Background: The quality of measurements is the main problem in clinical diagnostics. Only a well-designed and properly implemented quality control system ensures that real and precise measurement results are obtained. The aim of our study was to evaluate the quality of bone mineral density measurements in laboratories in Poland. Material/Methods: 15 laboratories from 9 cities participated in the study. The evaluation was performed on the basis of International Society for Clinical Densitometry recommendations and data from the literature. Part I of the evaluation comprised checking the calibration and stability of the densitometer, the safety of acquisition data, the documentation of services, and the reproducibility of measurements in patients. Part II comprised reproducibility, based on phantom testing, using European spine phantom and anthropomorphic spine phantom. Phantom measurements and analysis were done in a routine manner by native operators. Results: The only activity which was properly and regularly performed in all laboratories was calibration. The other activities were performed properly in less than half of the laboratories, and some of them only in single laboratories. In nearly half of the laboratories the reproducibility error exceeded the tolerance limit. Conclusions: The present study suggests that the quality of bone mineral density measurement in Poland is rather low. Introducing quality control in laboratories and training courses for operators is strongly recommended

Chronic mesenteric ischaemia: diagnostic and therapeutic difficulties

Chronic mesenteric ischaemia is most often caused by the development of atherosclerosis of two or three mesenteric arteries. Some patients require treatment not only because of significant symptoms, but also because of the potential risk of intestinal necrosis. This study presents the case of a 56-year-old female patient admitted to the Department due to severe abdominal pain, cyclic diarrhoea, and significant weight loss lasting for a period of 1.5 years. Duplex ultrasound and angioCT examinations showed complete occlusion of the proximal segment of the superior mesenteric artery. The patient was qualified to aorto-mesenteric graft surgery below the renal arteries. The segment of the saphenous vein that was used initially did not ensure sufficient circulation in the vicinity of the superior mesenteric artery. The vein was replaced by a PTFE prosthesis of greater diameter, which enabled a good treatment effect. Two years after the operation the patient is asymptomatic, has gained 10 kg, and the prosthesis remains patent - which was confirmed by means of Duplex ultrasound. The Authors mention the often delayed diagnosis in these patients, and need for the individual selection of the therapeutic method. Acta Angiol 2010; 16, 2: 85-92Przewlekłe niedokrwienie jelit jest najczęściej spowodowane rozwojem miażdżycy w obrębie dwóch lub trzech tętnic krezkowych. U części pacjentów konieczne jest leczenie, nie tylko ze względu na znaczne dolegliwości, lecz także z powodu potencjalnego ryzyka martwicy jelit. Opisano przypadek 56-letniej chorej z utrzymującymi się od 1,5 roku silnymi bólami brzucha, okresowymi biegunkami i znaczną utratą masy ciała. W doplerowskim badaniu USG i angiografii CT stwierdzono całkowitą niedrożność początkowego odcinka tętnicy krezkowej górnej. Pacjentkę zakwalifikowano do zabiegu pomostowania aortalno-krezkowego poniżej tętnic nerkowych. Wykorzystany początkowo odcinek żyły odpiszczelowej nie zapewnił wystarczającego krążenia w dorzeczu tętnicy krezkowej górnej. Żyłę zastąpiono protezą PTFE o większej średnicy, uzyskując dobry efekt leczenia. Dwa lata po operacji u chorej nie występują dolegliwości, jej masa ciała zwiększyła się o 10 kg, a w kontrolnym doplerowskim badaniu USG potwierdzono drożność protezy. Autorzy zwracają uwagę na często spóźnione rozpoznanie w tej grupie chorych i potrzebę indywidualnego doboru rodzaju zabiegu. Acta Angiol 2010; 16, 2: 85-9

Influence of nanoparticles of platinum on chicken embryo development and brain morphology

Platinum nanoparticles (NP-Pt) are noble metal nanoparticles with unique physiochemical properties that have recently elicited much interest in medical research. However, we still know little about their toxicity and influence on general health. We investigated effects of NP-Pt on the growth and development of the chicken embryo model with emphasis on brain tissue micro- and ultrastructure. The embryos were administered solutions of NP-Pt injected in ovo at concentrations from 1 to 20 μg/ml. The results demonstrate that NP-Pt did not affect the growth and development of the embryos; however, they induced apoptosis and decreased the number of proliferating cells in the brain tissue. These preliminary results indicate that properties of NP-Pt might be utilized in brain cancer therapy, but potential toxic side effects must be elucidated in extensive follow-up research

Vlasov Launcher Diagrammatic Design Using the RT Method, Journal of Telecommunications and Information Technology, 2021, nr 2

In this paper, a simple and fast method relied upon for designing a Vlasov launcher with a helical cut is proposed. The method is based on graphic interpretation of analytical relationships that link wave parameters (EM field mode) to the launcher’s geometrical dimensions. Using the ray tracing method, a simplified graphic analysis may be carried out. The results obtained are not significantly different from those of rigorous full-wave analyzes. The family of normalized curves that is created in the process greatly facilitates the stage of optimizing the geometrical parameters of the Vlasov launche

Review of Experimental Verification Methods of Gyrotron Quasi-optical Mode Converters, Journal of Telecommunications and Information Technology, 2020, nr 3

This survey presents a review of experimental methods relied upon while implementing gyrotron higher mode generation techniques and performing near electromagnetic field measurements in launcher and quasi-optical mode converters. In particular, the paper focuses on low power (cold) testing of gyrotron quasi-optical mode converters outside of the gyrotron, without the presence of high electromagnetic power and electron beam