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Search Results: 1 - 10 of 2452 matches for " Tomasz Piotrowski "
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Performance of the stochastic MV-PURE estimator in highly noisy settings
Tomasz Piotrowski,Isao Yamada
Statistics , 2013,
Abstract: The stochastic MV-PURE estimator has been developed to provide linear estimation robust to ill-conditioning, high noise levels, and imperfections in model knowledge. In this paper, we investigate the theoretical performance of the stochastic MV-PURE estimator under varying level of additive noise. More precisely, we prove that the mean-square-error (MSE) of this estimator in the low signal-to-noise (SNR) region is much smaller than that obtained with its full-rank version, the minimum-variance distortionless estimator, and that the gap in performance is the larger the higher the noise level. These results shed light on the excellent performance of the stochastic MV-PURE estimator in highly noisy settings obtained in simulations so far. We extend here previously conducted numerical simulations to demonstrate a new insight provided by results of this paper in practical applications.
Synthesis and properties of aromatic 1,3-diketones and bis-(1,3-diketones) obtained from acetophenone and phtalic acids esters
Jan Zawadiak,Marek Mrzyczek,Tomasz Piotrowski
European Journal of Chemistry , 2011, DOI: 10.5155/eurjchem.2.3.289-294.416
Abstract: Dibenzoylmethane and six aromatic 1,3-diketones containing a dibenzoylmethane moiety were synthesized from acetophenone and the appropriate ester in crossed-Claisen condensations. The synthesized diketones include derivatives containing carboxyl and ester groups; bis-(1,3-diketones) were also prepared. The absorption of UV radiation of the obtained compounds was investigated in various solvents, and their molar absorption coefficients were calculated. The ratio of tautomers and keto-enol equilibrium constants were calculated using 1H NMR techniques. Aromatic bis-(1,3-diketones) demonstrated strong hyperchromic effects. The keto-enol equilibrium of the investigated compounds is strongly shifted to the enol form, especially in non-polar solvents.
Influence of length of interval between pulses in PDR brachytherapy (PDRBT) on value of Biologically Equivalent Dose (BED) in healthy tissues
Janusz Skowronek,Julian Malicki,Grzegorz Zwierzchowski,Tomasz Piotrowski
Journal of Contemporary Brachytherapy , 2010,
Abstract: Purpose: Different PDR treatment schemas are used in clinical practice, however optimal length of interval between pulses still remains unclear. The aim of this work was to compare value of BED doses measured in surrounded healthy tissues according to different intervals between pulses in PDRBT. Influence of doses optimization on BED values was analyzed.Material and methods: Fifty-one patients treated in Greater Poland Cancer Centre were qualified for calculations.Calculations of doses were made in 51 patients with head and neck cancer, brain tumor, breast cancer, sarcoma, penis cancer and rectal cancer. Doses were calculated with the use of PLATO planning system in chosen critical points in surrounded healthy tissues. For all treatment plans the doses were compared using Biologically Equivalent Dose formula.Three interval lengths (1, 2 and 4 hours) between pulses were chosen for calculations. For statistical analysis Friedman ANOVA test and Kendall ratio were used.Results: The median value of BED in chosen critical points in healthy tissues was statistically related to the length of interval between PDR pulses and decreased exponentially with 1 hour interval to 4 hours (Kendall = from 0.48 to 1.0; p = from 0.002 to 0.00001).Conclusions: Prolongation of intervals between pulses in PDR brachytherapy was connected with lower values of BED doses in healthy tissues. It seems that longer intervals between pulses reduced the risk of late complications, but also decreased the tumour control. Furthermore, optimization influenced the increase of doses in healthy tissues.
室温长波光导探测器研究
Jozef,Piotrowski
红外与毫米波学报 , 1990,
Abstract: 从理论和实验上详细研究了室温长波HgCdTe光导探测器,提出了室温光导半导体的广义优值,计算了10.6μm HgCdTe探测器的优值和极限性能与组分和掺杂的关系。用HgCdTe外延层制作了光导探测器,描述了它的性能。结果表明10.6μm室温光导探测器的最佳探测率可高于1×10~8cmHz~(1/2)/W,已接近一般的热敏型探测器性能。
Blumberg property versus almost continuity
Z. Piotrowski
International Journal of Mathematics and Mathematical Sciences , 1987, DOI: 10.1155/s0161171287000127
Abstract: Some relations between the Blumberg property and almost continuity are established. A problem of S.-Y. Lin and Y.-F. Lin is completely resolved.
On the theorems of Y. Mibu and G. Debs on separate continuity
Zbigniew Piotrowski
International Journal of Mathematics and Mathematical Sciences , 1996, DOI: 10.1155/s0161171296000695
Abstract: Using a game-theoretic characterization of Baire spaces, conditions upon the domain and the range are given to ensure a “fat ” set C(f) of points of continuity in the sets of type X —{y}, y ¢ Y for certain almost separately continuous functions f:X —Y ¢ ’Z. These results (especially Theorem B) generalize Mibu's. First Theorem, previous theorems of the author, answers one of his problems as well as they are closely related to some other results of Debs [1] and Mibu [2].
My Brother's Teacher? Siblings and Literacy Development in the Home
Laura Sokal,Caroline Piotrowski
Education Research International , 2011, DOI: 10.1155/2011/253896
Abstract: Frequency of sibling literacy interactions were examined in 134 families with at least two children, where at least one of the children attended school in grade one to grade four. Parents in the majority of families reported that their children read together on a regular basis without a parent present. This held across various demographic constellations including gender of the older child. However, children from families with three or more children were less likely to read with their siblings. Implications for parents and teachers are discussed.
A note on metric preserving functions
Jozef Dobos,Zbigniew Piotrowski
International Journal of Mathematics and Mathematical Sciences , 1996, DOI: 10.1155/s0161171296000282
Abstract: The purpose of this note is to study modifications of the Euclidean metric on IR with the following property. There is a monotone sequence of closed balls with empty intersection.
Bibliographic Drug Information: A Guide for the Public Consumer
Bob Perdue,Chris Piotrowski
Journal of Educational Media & Library Sciences , 2004,
Abstract: The present study provides for a research strategy, limited to print bibliographic sources, on obtaining basic and clinical information on pharmaceuticals. Selectively, 20 titles are described and discussed under four descriptive categories (Condensed General References, General Public Consumption, Adverse Reactions and lnteractions, and Comprehensive Compendiums). This bibliographic framework is presented as a potential template for reference staff when assisting library users. The additional availability of these print sources in CDROM and online format are also noted.
10-letnie ryzyko zgonu sercowego-naczyniowego a opieka medyczna
Aleksandra Pytlak,Walerian Piotrowski
Polish Journal of Cardiology , 2005,
Abstract: Wprowadzenie: 10-letnie ryzyko zgonu sercowo-naczyniowego, które opiera si na szacunku liczby i nasilenia czynników ryzyka, powinno znale odzwierciedlenie w post powaniu lekarskim, obejmuj cym zarówno farmakoterapi , jak równie zalecenia modyfikacji stylu ycia. Cel pracy: Analiza opieki medycznej w zale no ci od 10-letniego ryzyka zgonu sercowo-naczyniowego ocenianego wed ug funkcji SCORE oraz oszacowanie stanu zdrowia ludno ci prawobrze nej Warszawy. Materia i metodyka: W 2001 r. zbadano subpopulacj 488 m czyzn i 528 kobiet w wieku 40-70 lat, mieszkaj cych w Warszawie (program MONICA BIS). Ryzyko oceniono wed ug funkcji SCORE (ma e <5%, du e >5%), a opieraj c si na odpowiedziach na pytania z kwestionariusza zanalizowano opiek medyczn . Wyniki: Du e ryzyko zgonu sercowo-naczyniowego stwierdzono u 58% m czyzn i 38% kobiet i odsetek ten rós wraz z wiekiem badanych. Ponadto w ród m czyzn, cz ciej ni u kobiet, w m odszym wieku obserwowano du e ryzyko. Odsetek osób, którym wykonano pomiar ci nienia t tniczego krwi w czasie wizyty lekarskiej rós wraz ze wzrostem ryzyka od 69% w grupie ma ego ryzyka do 87% w grupie du ego ryzyka. Odsetek palaczy, którym zalecono zaprzestanie palenia rós od 59% w grupie ma ego ryzyka do 77% w grupie du ego ryzyka. Porad dietetyczn otrzymywa o od 34% osób zg aszaj cych si do lekarza z ma ym ryzykiem do 52% osób z du ym ryzykiem, a zalecenie zwi kszenia aktywno ci fizycznej do 33% osób z du ym ryzykiem zgonu sercowo-naczyniowego. W grupie m czyzn z nadci nieniem t tniczym (po wy czeniu nowo rozpoznanego nadci nienia) leczonych by o oko o 54% z ma ym ryzykiem i 37% z du ym, a w grupie kobiet odpowiednio 61% i 55%. Odsetek osób z hiperlipidemi (po wy czeniu nowo rozpoznanej hiperlipidemii), które by y leczone wynosi u m czyzn z ma ym ryzykiem oko o 14%, za z du ym - oko o 11% (u kobiet odpowiednio 20% i 11%). Wnioski: Ponad po owa populacji m czyzn i oko o 1/3 populacji kobiet w wieku 40-70 lat, mieszkańców prawobrze nej Warszawy, charakteryzowa a si du ym 10-letnim ryzykiem zgonu sercowo-naczyniowego. Wraz ze wzrostem ryzyka post powanie lekarskie bardziej zbli a o si do standardów, nadal jednak istnieje rozd wi k pomi dzy zaleceniami a praktyk .
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