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Wyszukujesz frazę "b]-factor" wg kryterium: Temat


Tytuł:
A Neighborhood Condition for Fractional ID-[A, B]-Factor-Critical Graphs
Autorzy:
Zhou, Sizhong
Yang, Fan
Sun, Zhiren
Powiązania:
https://bibliotekanauki.pl/articles/31340936.pdf
Data publikacji:
2016-05-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
graph
minimum degree
neighborhood
fractional [a
b]-factor
fractional ID-[a
b]-factor-critical graph
Opis:
Let $G$ be a graph of order $n$, and let $a$ and $b$ be two integers with $ 1 \le a \le b $. Let $ h : E(G) \rightarrow [0, 1] $ be a function. If \( a \le \Sigma_{ e \ni x } h(e) \le b \) holds for any $ x \in V (G) $, then we call $ G[F_h] $ a fractional $ [a, b] $-factor of $ G $ with indicator function $ h $, where $ F_h = \{ e \in E(G) : h(e) > 0 \} $. A graph $G$ is fractional independent-set-deletable $[a, b]$-factor-critical (in short, fractional ID-$[a, b]$-factor-critical) if $ G − I $ has a fractional $ [a, b] $-factor for every independent set $I$ of $G$. In this paper, it is proved that if $ n \ge \frac{(a+2b)(2a+2b-3)+1}{b} $, $ \delta (G) \ge \frac{bn}{a+2b} + a $ and $ | N_G(x) \cup N_G(y) | \ge \frac{(a+b)n}{a+2b} $ for any two nonadjacent vertices $ x, y \in V (G) $, then $ G $ is fractional ID-$[a, b]$-factor-critical. Furthermore, it is shown that this result is best possible in some sense.
Źródło:
Discussiones Mathematicae Graph Theory; 2016, 36, 2; 409-418
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
More on even [a,b]-factors in graphs
Autorzy:
Khodkar, Abdollah
Xu, Rui
Powiązania:
https://bibliotekanauki.pl/articles/743747.pdf
Data publikacji:
2007
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
[a,b]-factor
spanning graph
edge-connectivity
Opis:
In this note we give a characterization of the complete bipartite graphs which have an even (odd) [a,b]-factor. For general graphs we prove that an a-edge connected graph G with n vertices and with δ(G) ≥ max{a+1,an/(a+b) + a - 2} has an even [a,b]-factor, where a and b are even and 2 ≤ a ≤ b. With regard to the edge-connectivity this result is slightly better than one of the similar results obtained by Kouider and Vestergaard in 2004 and unlike their results, this result has no restriction on the order of graphs.
Źródło:
Discussiones Mathematicae Graph Theory; 2007, 27, 1; 193-204
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Degree Condition Implying Ore-Type Condition for Even [2, b]-Factors in Graphs
Autorzy:
Tsuchiya, Shoichi
Yashima, Takamasa
Powiązania:
https://bibliotekanauki.pl/articles/31341635.pdf
Data publikacji:
2017-08-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
[ a, b ]-factor
even factor
2-edge-connected
minimum degree
Opis:
For a graph $G$ and even integers $ b \ge a \ge 2 $, a spanning subgraph $F$ of $G$ such that $ a \le \text{deg}_F (x) \le b $ and $ \text{deg}_F (x) $ is even for all $ x \in V (F) $ is called an even $[a, b]$-factor of $G$. In this paper, we show that a 2-edge-connected graph $G$ of order $n$ has an even $[2, b]$-factor if $ \text{max} \{ \text{deg}_G (x) , \text{deg}_G (y) \} \ge \text{max} \{ \frac{2n}{2+b} , 3 \} $ for any nonadjacent vertices $x$ and $y$ of $G$. Moreover, we show that for $ b \ge 3a$ and $a > 2$, there exists an infinite family of 2-edge-connected graphs $G$ of order $n$ with $ \delta (G) \ge a$ such that $G$ satisfies the condition $ \text{deg}_G (x) + \text{deg}_G (y) > \frac{2an}{a+b} $ for any nonadjacent vertices $x$ and $y$ of $G$, but has no even $[a, b]$-factors. In particular, the infinite family of graphs gives a counterexample to the conjecture of Matsuda on the existence of an even $[a, b]$-factor.
Źródło:
Discussiones Mathematicae Graph Theory; 2017, 37, 3; 797-809
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Independence Number, Connectivity and All Fractional (a, b, k)-Critical Graphs
Autorzy:
Yuan, Yuan
Hao, Rong-Xia
Powiązania:
https://bibliotekanauki.pl/articles/31343586.pdf
Data publikacji:
2019-02-01
Wydawca:
Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:
independence number
connectivity
fractional [a
b]-factor
frac- tional (a
b
k)-critical graph
all fractional (a
Opis:
Let $G$ be a graph and $a$, $b$ and $k$ be nonnegative integers with $ 1 \le a \le b $. A graph $G$ is defined as all fractional $(a, b, k)$-critical if after deleting any $k$ vertices of $G$, the remaining graph has all fractional $[a, b]$-factors. In this paper, we prove that if \( \kappa(G) \ge \text{max} \{ \tfrac{(b+1)^2+2k}{2}, \tfrac{(b+1)^2 \alpha(G)+4ak}{4a} \} \), then $G$ is all fractional $(a, b, k)$-critical. If $k = 0$, we improve the result given in [Filomat 29 (2015) 757-761]. Moreover, we show that this result is best possible in some sense.
Źródło:
Discussiones Mathematicae Graph Theory; 2019, 39, 1; 183-190
2083-5892
Pojawia się w:
Discussiones Mathematicae Graph Theory
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Potential role of transforming growth factor β1 in drug resistance of tumor cells.
Autorzy:
Stoika, Rostyslav
Yakymovych, Mariya
Souchelnytskyi, Serhiy
Yakymovych, Ihor
Powiązania:
https://bibliotekanauki.pl/articles/1043628.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
tumor cells
drug resistance
transforming growth factor b1
Opis:
Acquired drug resistance of tumor cells is frequently observed in cancer patients undergoing chemotherapy. We studied murine leukemia L1210 cells sensitive and resistant to the cytotoxic action of cisplatin and showed that cisplatin-resistant leukemia cells were also refractory to TGF β1-dependent growth inhibition and apoptosis. Addressing the question about the mechanisms responsible for the cross-resistance to cisplatin and TGF β1, we found that cisplatin- and TGF β1-resistant L1210 cells possessed a decreased expression of type I TGF β1 receptor, while the expression of type II TGF β1 receptor was not affected. Western blot analysis of Smad proteins 2, 3, 4, 6, and 7, which participate in signal transduction pathway down-stream of the TGF b1 receptors, revealed an increased expression of Smad 6, inhibiting TGF b1 action, only in cisplatin- and TGF β1-resistant L1210 cells. TGF β1 and especially the cytotoxic mistletoe agglutinin increased Smad 6 expression in TGF β1-sensitive but not in TGF β1-resistant L1210 cells. TGF β1-resistant L1210 cells also differed from TGF β1-sensitive cells by the lack of expression of the pro-apoptotic p53 protein and higher level of expression of the anti-apoptotic Bcl-2 protein. Thus, the described co-expression of tumor cell refractoriness to an anti-cancer drug and to the inhibitory cytokine TGF β1 is accompanied by multiple changes in the TGF β1 signal transduction pathway and in other regulatory systems of the target cells. Besides, we found that various anti-tumor drugs and cytotoxic plant lectins increased the level of TGF b1 expression in both TGF β1-sensitive and -resistant L1210 cells. A hypothesis is proposed that TGF β1 can at least partly mediate the effect of cell-stressing agents and, thus, the development of TGF β1 resistance may be responsible for the appearance of tumor cell refractoriness to the action of some anti-cancer drugs.
Źródło:
Acta Biochimica Polonica; 2003, 50, 2; 497-508
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of differential serum expression of three factors and pulmonary function in patients with silicosis
Autorzy:
Zhu, Ying
Duan, Xia Yu
Cheng, Yun Qi
Yao, Xin Jing
Xu, Hong
Zhang, Kui Sheng
Li, Feng Shi
Yang, Fang
Liu, Liang He
Yuan, Xiang Ju
Powiązania:
https://bibliotekanauki.pl/articles/2086531.pdf
Data publikacji:
2021-08-05
Wydawca:
Instytut Medycyny Pracy im. prof. dra Jerzego Nofera w Łodzi
Tematy:
silicosis
pulmonary function
early diagnosis
ROC
PTPN2
factor B
Opis:
ObjectivesSilicosis is a chronic occupational lung disease. As was previously found by the authors, some proteins increased in the lung tissue of activated rats, and protein tyrosine phosphatase non-receptor type 2 (PTPN2), factor B, and vaccinia-related kinase 1 (VRK1) showed highly differential expressions.Material and MethodsIn this study, serum and bronchoalveolar lavage fluid samples were collected from patients with silicosis and healthy people to verify the expression of PTPN2, factor B, and VRK1. The diagnostic value of differentially expressed proteins for silicosis was judged.ResultsThe expression levels of serum PTPN2, VRK1, and factor B in patients with silicosis were significantly higher than those in the control group (p < 0.01). Higher serum PTPN2 and factor B concentrations significantly and negatively correlated with the ratio of forced expiratory volume in 1 s to forced vital capacity (FEV1/FVC), maximum vital capacity (VCmax), FEV1, and FVC, suggesting that the high expression of PTPN2 and factor B is associated with decreased pulmonary ventilation function and restrictive ventilatory impairment in patients with silicosis. All area under curve (AUC) measurements generated from single detection events were >0.744, with PTPN2 reaching the highest value (0.858). The AUC, sensitivity, and specificity for the combined diagnosis using factor B and PTPN2 were 0.907, 86.91% and 85.07%, respectively, for factor B and PTPN2. The 3 differentially expressed proteins are potential classes of predictive biomarkers for silicosis.ConclusionsRegarding the economy and test practicality, the best diagnostic combination is factor B and PTPN2 for the analysis of AUC, sensitivity and specificity.
Źródło:
International Journal of Occupational Medicine and Environmental Health; 2021, 34, 4; 527-540
1232-1087
1896-494X
Pojawia się w:
International Journal of Occupational Medicine and Environmental Health
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Influence of Aflatoxin B1 on the Concentration of Nuclear Factor κB in Rats’ Livers
Wpływ aflatoksyny B1 na stężenie czynnika jądrowego κB w wątrobach szczurów
Autorzy:
Woźniakowski, Mateusz
Woźniakowska, Nikola
Zuzak, Tomasz
Świerszcz, Łukasz
Wójciak-Czuła, Marta
Borzęcki, Andrzej
Nieradko-Iwanicka, Barbara
Powiązania:
https://bibliotekanauki.pl/articles/32697700.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Medycyny i Techniki Hiperbarycznej
Tematy:
aflatoxin B1
nuclear factor κB
liver
aflatoksyna B1
czynnik jądrowy κB
wątroba
Opis:
Introduction. Aflatoxins are metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Due to the high prevalence of aflatoxin-containing products they are common issue of the observational studies. Observational studies have demonstrated the hepatotoxic effects of aflatoxins in humans. However, the exact pathogenetic mechanisms of the effect of aflatoxin B1 on the above-mentioned hepatotoxicity have not yet been known. Aim of the study. The aim of the study was to assess the toxic effects of different doses of aflatoxin B1. The analyze was performed using assessment of concentration of NF-κB in liver tissue homogenates after a 7-day intoxication with this mycotoxin. Material and methods. The studies were carried out on Wistar male rats which were selected randomly, according to the principle of simultaneity for the control group and the study groups. The concentration of NK-κB was determined by immunoenzymatic ELISA in the obtained supernatants of liver taken from decapitated animals. The statistical analysis was performed with Statistica 13.3 (Statsoft, USA). Results. The statistical significance of the difference between the concentrations in the control and study group receiving 1.0 mg/kg of aflatoxin B1 and between the control and study group who received aflatoxin B1 at a dose of 2.0 mg/kg body weight (p <0,05) were demonstrated. A significant relationship was also found between the level of dose of aflatoxin B1 administered to the rats and the concentration of NF-κB. Negative correlations were obtained. The higher dose administered to rats - the lower level of measured concentration of NF-κB. Conclusions. The study of the influence of aflatoxin B1 on the level of NF-κB transcription factor may significantly contribute to understand the mechanism of its action, influence on inflammatory, apoptotic and carcinogenic processes in the liver and determine its safe level in food intended for humans and animals.
Wstęp. Aflatoksyny to metabolity wytwarzane przez Aspergillus flavus i Aspergillus parasiticus. Ze względu na duże rozpowszechnienie produktów zawierających aflatoksyny są one częstym przedmiotem badań obserwacyjnych. W dotychczasowych badaniach potwierdzono hepatotoksyczne działanie aflatoksyn u ludzi. Jednak dokładne mechanizmy patogenetyczne wpływu aflatoksyny B1 na wspomnianą hepatotoksyczność nie są jeszcze znane. Cel pracy. Celem pracy była ocena toksycznego efektu różnych dawek aflatoksyny B1. Analizę przeprowadzono przez ocenę stężenia NF-κB w homogenatach tkanki wątroby po 7-dniowym zatruciu tą mykotoksyną. Materiał i metody. Badania przeprowadzono na samcach szczurów rasy Wistar, które zostały wybrane losowo, zgodnie z zasadą jednoczesności dla grupy kontrolnej i grupy badawczej. Stężenie NK-κB oznaczono immunoenzymatycznym testem ELISA w otrzymanych supernatantach wątroby pobranych od zwierząt uśmierconych metodą dekapitacji. Analizę statystyczną przeprowadzono w programie Statistica 13.3 (Statsoft, USA). Wyniki. Stwierdzono różnice istotne statystycznie między stężeniami NK-κB w grupie kontrolnej i badanej otrzymującej 1,0 mg/kg aflatoksyny B1 oraz między grupą kontrolną i badaną, która otrzymywała aflatoksynę B1 w dawce 2,0 mg/kg masy ciała (p <0,05 ). Stwierdzono również istotną zależność pomiędzy poziomem dawki podawanej szczurom aflatoksyny B1 a stężeniem NF-κB. Uzyskano korelacje ujemne. Wyższa dawka podawana szczurom powodowała niższy poziom mierzonego stężenia NF-κB. Wnioski. Badanie wpływu aflatoksyny B1 na poziom czynnika transkrypcyjnego NF-κB może istotnie przyczynić się do zrozumienia mechanizmu jej działania, wpływu na procesy zapalne, apoptotyczne i kancerogenne w wątrobie oraz określenia jego bezpiecznego poziomu w żywności przeznaczonej dla ludzi i zwierząt.
Źródło:
Polish Hyperbaric Research; 2021, 1(74); 67-75
1734-7009
2084-0535
Pojawia się w:
Polish Hyperbaric Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The role of nuclear factor-κB in the development of autoimmune diseases: a link between genes and environment
Autorzy:
Kuryłowicz, Alina
Nauman, Janusz
Powiązania:
https://bibliotekanauki.pl/articles/1040661.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
autoimmune diseases
nuclear factor-κB (NF-κB)
genetic polymorphism
NF-κB targeted strategies
Opis:
Although autoimmune diseases are relatively common, mechanisms that lead to their development remain largely unknown. Nuclear factor-κB (NF-κB), as a key transcription factor involved in the regulation of immune responses and apoptosis, appears to be a good candidate for studies on the pathogenesis of autoimmunity. This review presents how perturbations of the NF-κB signaling pathway may contribute to self-tolerance failure, initiation of autoimmune inflammatory response as well as its persistent maintenance and therefore to the development of common autoimmune diseases including rheumatoid arthritis, multiple sclerosis, type 1 diabetes mellitus, thyroid autoimmune diseases, systemic lupus erythematosus as well as inflammatory bowel diseases and psoriasis. A special emphasis is put on the genetic variations in the NF-κB related genes and their possible association with susceptibility to autoimmune diseases, as well as on the therapeutic potential of the NF-κB targeted strategies in the treatment of autoimmunity.
Źródło:
Acta Biochimica Polonica; 2008, 55, 4; 629-647
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnolol inhibits Streptococcus suis-induced inflammation and ROS formation via TLR2/MAPK/NF-κB signaling in RAW264.7 cells
Autorzy:
Wang, J.
Sun, Y.
Zhang, L.
Xu, W.
You, J.
Lu, H.
Song, Y.
Wei, J.
Li, L.
Powiązania:
https://bibliotekanauki.pl/articles/2087779.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
magnolol
Streptococcus suis
Toll-like receptor2
mitogen-activated protein kinase
nuclear factor Kappa B
Źródło:
Polish Journal of Veterinary Sciences; 2018, 21, 1; 111-118
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The nuclear factor-kappaB (NF-κB): from a versatile transcription factor to a ubiquitous therapeutic target
Autorzy:
Yates, Laura
Górecki, Dariusz
Powiązania:
https://bibliotekanauki.pl/articles/1041153.pdf
Data publikacji:
2006
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
nuclear factor-kappaB (NF-κB)
IκB kinase complex (IKK)
transcription factors
inhibitory-kappaB (IκB)
Opis:
The nuclear factor-kappaB (NF-κB) transcription factors regulate a plethora of cellular pathways and processes including the immune response, inflammation, proliferation, apoptosis and calcium homeostasis. In addition to the complexity of its physiological roles, the composition and function of this family of proteins is very complicated. While the basic understanding of NF-κB signalling is extensive, relatively little is know of the in vivo dynamics of this pathway or what controls the balance between various outcomes. Although we know a large number of NF-κB-responsive genes, the contribution of these genes to a specific response is not always clear. Finally, the involvement of NF-κB in pathological processes is only now beginning to be unravelled. In addition to cancer and immunodeficiency disorders, altered regulation of NF-κB has been associated with several inherited diseases. These findings indicate that modulation of the NF-κB pathways may be beneficial. However, our limited knowledge of NF-κB signalling hinders therapeutic approaches: in many situations it is not clear whether the enhancement or inhibition of NF-κB activity would be beneficial or which pathways to interfere with and what the required level of activation is. Further studies of the role of NF-κB are needed as these may result in novel therapeutic strategies for a wide variety of diseases.
Źródło:
Acta Biochimica Polonica; 2006, 53, 4; 651-662
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
MADS-box genes are involved in floral development and evolution.
Autorzy:
Saedler, Heinz
Becker, Annette
Winter, Kai-Uwe
Kirchner, Charlotte
Theißen, Günter
Powiązania:
https://bibliotekanauki.pl/articles/1044122.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
transcription factor
B- and Bs-functions
floral bauplan
phylogeny
Opis:
MADS-box genes encode transcription factors in all eukaryotic organisms thus far studied. Plant MADS-box proteins contain a DNA-binding (M), an intervening (I), a Keratin-like (K) and a C-terminal C-domain, thus plant MADS-box proteins are of the MIKC type. In higher plants most of the well-characterized genes are involved in floral development. They control the transition from vegetative to generative growth and determine inflorescence meristem identity. They specify floral organ identity as outlined in the ABC model of floral development. Moreover, in Antirrhinum majus the MADS-box gene products DEF/GLO and PLE control cell proliferation in the developing flower bud. In this species the DEF/GLO and the SQUA proteins form a ternary complex which determines the overall "Bauplan" of the flower. Phylogenetic reconstructions of MADS-box sequences obtained from ferns, gymnosperms and higher eudicots reveal that, although ferns possess already MIKC type genes, these are not orthologous to the well characterized MADS-box genes from gymnosperms or angiosperms. Putative orthologs of floral homeotic B- and C-function genes have been identified in different gymnosperms suggesting that these genes evolved some 300-400 million years ago. Both gymnosperms and angiosperms also contain a hitherto unknown sister clade of the B-genes, which we termed Bsister. A novel hypothesis will be described suggesting that B and Bsister might be involved in sex determination of male and female reproductive organs, respectively.
Źródło:
Acta Biochimica Polonica; 2001, 48, 2; 351-358
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Metal responsive transcription factor 1 (MTF-1) regulates zinc dependent cellular processes at the molecular level
Autorzy:
Grzywacz, Agata
Gdula-Argasińska, Joanna
Muszyńska, Bożena
Tyszka-Czochara, Małgorzata
Librowski, Tadeusz
Opoka, Włodzimierz
Powiązania:
https://bibliotekanauki.pl/articles/1038990.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
metal responsive-transcription factor 1
cell signaling
inflammation
NF-κB
Opis:
Metal responsive transcription factor 1 (MTF-1) is a zinc dependent transcription factor which is involved in the regulation of intracellular signaling pathways. MTF-1 regulates the expression of two streams of genes functioning in metal homeostasis and anti-oxidative response. MTF-1 acts in the process of binding of toxic metal ions in the cell, due to the activation of the expression of metallothioneins (MTs). Additionally, MTF-1 regulates transcription of genes involved in the sequestration of zinc and its intracellular transport. Disruption of zinc and MT homeostasis has an indispensable influence on the development of several pathological states. Moreover, by increasing MT activity, MTF-1 can effectively protect cells from oxidative and hypoxic stresses. The mechanism of MTF-1 action in cells includes the regulation of the proper immune response through activation/repression of anti- and pro-inflammatory cytokines. MTF-1 function in immune response is related to nuclear factor-κB (NF-κB) activity. Synthesis of insulin is also related to the activity of this transcription factor and zinc balance. Insulin transport also depends on zinc. In pancreatic β-cells, several types of the zinc transporters are found. Zinc transporters coordinated action is crucial for the synthesis and secretion of insulin. Disturbances in the regulation of signaling pathways connected with MTF-1 function can entail further alterations in zinc intracellular status and this growing imbalance can promote the pathophysiology of degenerative disorders.
Źródło:
Acta Biochimica Polonica; 2015, 62, 3; 491-498
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An improved calculation method of inductance and capacitances in ?1 circuits for resonant power amplifiers
Autorzy:
Modzelewski, J.
Kulma, K.
Powiązania:
https://bibliotekanauki.pl/articles/140508.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
induktorowy współcynnik jakości
klasa A
klasa AB
klasa B
klasa C
resonant-circuit design
impedance transformation
inductor quality factor
loaded quality factor
Class A
class AB
class B
class C
Opis:
In the paper an improved method of calculation of the inductance and capacitances in the ?1 circuit for Class A, AB, B, and C resonant power amplifiers is presented. This method is based on an assumption that the quality factor of the inductor is inite and the capacitors are lossless. The input parameters for calculations are the amplifier load resistance, the transistor load resistance, the quality factor of the inductor, the loaded quality factor of the designed circuit, and the operating frequency. The presented method allows reducing the required regulation range of ?1 circuits elements In built resonant amplifiers as compared to the traditional calculation methods assuming lossless capacitors and inductor. This advantage is important, in particular, for long- and medium-wave transistor power amplifiers, where capacitances in ?1 circuits are high comparing to typical trimming capacitors.
Źródło:
Archives of Electrical Engineering; 2012, 61, 2; 221-237
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charakterystyka mineralogiczno-geochemiczna osadów westfalu Lubelskiego Zagłębia Węglowego wzbogaconych w mangan
Mineralogical and geochemical characterization deposits from the Westphalian of the Lublin Coal Basin enriched in manganese
Autorzy:
Kokowska-Pawłowska, M.
Krzeszowska, E.
Powiązania:
https://bibliotekanauki.pl/articles/113472.pdf
Data publikacji:
2016
Wydawca:
STE GROUP
Tematy:
seria paraliczna
seria limniczna
westfal A i B
formacja lubelska
mangan
wskaźnik wzbogacenia
paralic series
limnic series
Westphalian A i B
Lublin formation
manganese
enrichment factor
Opis:
W pracy przedstawiono wyniki badań petrograficznych i geochemicznych iłowców i mułowców z serii paralicznej i limnicznej (westfal A i B) Lubelskiego Zagłębia Węglowego zawierających podwyższone zawartości manganu. Analizy geochemiczne obejmowały oznaczenie zawartości Fe, V, Ca, Mg i Ni oraz ich korelacje z zawartością Mn. Badania wykazały, że we wszystkich próbkach wyraźnie wzbogaconych w Mn zawartość Fe jest również podwyższona, a pomiędzy wartościami wskaźników wzbogacenia EfMn i EfFe występuje silna korelacja. Stwierdzono ponadto, że podwyższonej zawartości Mn czasami towarzyszy podwyższona zawartość V, Ni lub Mg.
The paper presents the results of petrographic and geochemical researches of the claystones and mudstones with high content of Mn from paralic and limnic series (Westphalian A and B) of the Lublin Coal Basin. Geochemical analysis included the content of Fe, V, Ca, Mg and Ni and their correlation with the content of Mn. Studies have shown that, for all samples significantly enriched in Mn concentration of Fe is also high and the correlation between the values of the enrichment factor EfMn and EfFe is very strong. It was also found that the increased content of Mn sometimes is accompanied by increased content of V, Ni or Mg.
Źródło:
Systemy Wspomagania w Inżynierii Produkcji; 2016, 5 (17); 121-133
2391-9361
Pojawia się w:
Systemy Wspomagania w Inżynierii Produkcji
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rola VEGF, czynnika neurotroficznego i proangiogennego w patogenezie choroby Alzheimera
Role of VEGF, neurotrophic and proangiogenic factor in pathogenesis of Alzheimer’s disease
Autorzy:
Nowacka, Marta
Obuchowicz, Ewa
Powiązania:
https://bibliotekanauki.pl/articles/1057990.pdf
Data publikacji:
2011
Wydawca:
Medical Communications
Tematy:
Alzheimer’s disease
b-amyloid
modele transgeniczne choroby Alzheimera
transgenic models
treatment of AD
vascular endothelial growth factor (VEGF)
leczenie
naczyniowo-śródbłonkowy czynnik wzrostu (VEGF)
choroba Alzhaimera
modele transgeniczne choroby Alzhaimer'a
Opis:
Currently, neurodegenerative disorders represent one of the most serious diseases the mankind is struggling with. An increased morbidity rate of Alzheimer’s disease seems to be associated with general population aging. Despite the fact that the intensive studies have been conducted in many research centres for several years, etiopathogenesis of Alzheimer’s disease is still not fully understood. Furthermore, there is no drug which could, at least, inhibit progress of this disease effectively. Vascular endothelial growth factor (VEGF) is well-characterized proangiogenic substance, essential for the formation of new blood vessels during embryogenesis as well as others pathological condition. Recently, a new role for VEGF as a neurotrophic factor has been emerged. In the developing nervous system, VEGF plays a pivotal role in neuronal proliferation and guidance of neuronal development process. As proangiogenic and neurotrophic factor, VEGF has been suggested to be involved in the pathogenesis of Alzheimer’s disease. In patients suffering fromthis disease patients abnormal regulation of VEGF expression have been reported. Moreover, an interaction between VEGF and b-amyloid has been evidenced in in vitro studies on cell cultures and in vivo studies conducted on transgenic lab animals. In consequence, these data have stimulated an increasing interest in assessing the therapeutic potential of VEGF pharmacological modulation in treatment of Alzheimer’s disease.
Choroby neurodegeneracyjne należą do najpoważniejszych schorzeń, z jakimi zmaga się obecnie medycyna. Wydaje się, iż obserwowany wzrost częstości występowania choroby Alzheimera w dużej mierze wiąże się z ogólnym starzeniem się ludzkiej populacji. Mimo intensywnych badań prowadzonych od kilkudziesięciu lat etiopatogeneza tej choroby nie jest poznana, nie znamy również leku, który przynajmniej hamowałby skutecznie postęp tej choroby. Naczyniowo-śródbłonkowy czynnik wzrostu (vascular endothelial growth factor, VEGF) jest dobrze scharakteryzowanym czynnikiem proangiogennym, niezbędnym do powstawania nowych naczyń krwionośnych zarówno podczas rozwoju zarodkowego, jak i w warunkach patologicznych. Badania przeprowadzone w ostatnich latach wskazały na nową rolę VEGF jako czynnika neurotroficznego. Podczas rozwoju układu nerwowego VEGF odgrywa kluczową rolę nie tylko w różnicowaniu i tworzeniu sieci naczyń w rozwijającym się mózgu, lecz także w proliferacji neuronów oraz w kierowaniu procesem rozwoju neuronalnego. Obecnie uważa się, że VEGF jako czynnik proangiogenny i neurotroficzny prawdopodobnie bierze udział w patogenezie choroby Alzheimera. U osób cierpiących na tę chorobę stwierdzono nieprawidłową regulację ekspresji VEGF. Zarówno w badaniach in vitro przeprowadzonych na hodowlach komórkowych, jak i w badaniach in vivo na zwierzęcych modelach transgenicznych stwierdzono występowanie interakcji między VEGF a b-amyloidem. Te przesłanki zainspirowały badaczy do podjęcia badań nad ewentualnym wykorzystaniem farmakologicznej modulacji VEGF w terapii choroby Alzheimera.
Źródło:
Aktualności Neurologiczne; 2011, 11, 2; 123-130
1641-9227
2451-0696
Pojawia się w:
Aktualności Neurologiczne
Dostawca treści:
Biblioteka Nauki
Artykuł

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