664 research outputs found

    Mach's Principle and Model for a Broken Symmetric Theory of Gravity

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    We investigate spontaneous symmetry breaking in a conformally invariant gravitational model. In particular, we use a conformally invariant scalar tensor theory as the vacuum sector of a gravitational model to examine the idea that gravitational coupling may be the result of a spontaneous symmetry breaking. In this model matter is taken to be coupled with a metric which is different but conformally related to the metric appearing explicitly in the vacuum sector. We show that after the spontaneous symmetry breaking the resulting theory is consistent with Mach's principle in the sense that inertial masses of particles have variable configurations in a cosmological context. Moreover, our analysis allows to construct a mechanism in which the resulting large vacuum energy density relaxes during evolution of the universe.Comment: 9 pages, no figure

    Bells as memorials in South Africa to the Great (1914-18) War

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    The contribution of South Africa to the allied cause in the Great War, and the sacrifice of so many lives of the White and Coloured populations, is memorialised on bells of the Cape Town carillon, on ringing, and on clock and other bells. The contribution of the Black population awaits recognition. Restoration of the Cape Town carillon so that it can again be played effectively, would be a fitting memorial to those who lost their lives in the non-combative roles that were open to the majority population of South Africa. Completion of the ring at what is now Queenstown cathedral would also be a fitting tribute to the bravery and unstinting service of so many South Africans during the Great War.Colin Lewis was Professor of Geography at Rhodes University, Grahamstown, South Africa from 1989 until his retirement at the end of 2007. In 1990, with the strong support of the incumbent Vice-Chancellor, Dr Derek Henderson, he instigated the Certificate in Change Ringing (Church Bell Ringing) in the Rhodes University Department of Music and Musicology - the first such course to be offered in Africa. Since that date he has lectured in the basic theory, and taught the practice of change ringing. He is the Ringing Master of the Cathedral of St Michael and St George, Grahamstown, South Africa

    Modulation of cytokine release and neutrophil function by granulocyte colony-stimulating factor during endotoxemia in humans

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    In this double-blind, cross-over, placebo-controlled, randomized study, two groups of eight healthy male volunteers were challenged with endotoxin (4 ng/kg) on two occasions, once in conjunction with placebo and once with granulocyte colony-stimulating factor (G-CSF; 5 microg/kg). In group 1, G-CSF was administered intravenously 2 hours before endotoxin challenge; in group 2, G-CSF was administered subcutaneously 24 hours before endotoxin challenge. In group 1, G-CSF significantly enhanced the release of tumor necrosis factor (TNF), interleukin-6 (IL-6), IL-8, IL-1 receptor antagonist (IL-1ra), and soluble TNF receptors. In group 2, G-CSF significantly reduced IL-8 concentrations and modestly attenuated TNF and IL-6 levels. In this group, IL-1ra and soluble TNF receptors were enhanced by G-CSF pretreatment and lipopolysaccharide (LPS)-induced soluble TNF receptor release was further augmented, whereas LPS-induced IL-1ra concentrations remained unaltered. Both pretreatments with G-CSF increased LPS-induced peripheral neutrophilia; the expression of CD11b, CD18, and CD67; and the release of elastase and lactoferrin. Both pretreatments also down-regulated neutrophil L-selectin expression and prevented the endotoxin-induced pulmonary neutrophil accumulation during the first 2 hours after endotoxin challenge. These data indicate that two different pretreatments with G-CSF result in differential effects on LPS-induced cytokine release but similar effects on LPS-induced neutrophil activation and changes in expression of cell surface molecules. Finally, regardless of the effects of G-CSF on LPS-induced cytokine release, G-CSF blocks LPS-induced pulmonary granulocyte accumulatio

    Улучшение метрологических характеристик генераторов электрических сигналов с учётом шумов элементов

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    Объектами исследования являются метрологические характеристики генератора сигналов прецизионного ГС-50: погрешность уровня выходного напряжения, коэффициент гармоник. Данная работа ставит целью компьютерное моделирование генератора с учетом шумов элементов на предмет исследования его выходных параметров. В ходе работы был выбран и изучен программный пакет Multisim для дальнейшего моделирования, собраны схемы инвертора и интегратора, проведено их моделирование и исследование В результате работы была получена модель генератора с характеристиками соответствующими реальным характеристикам генератора сигналов прецизионного ГС-50.The objects of research are metrological characteristics of the precision GS-50 signal generator: the error of the output voltage level, the coefficient of harmonics. This work aims at computer simulation of the generator taking into account the noise of elements in order to study its output parameters. In the course of the work, the Multisim software package was selected and studied for further modeling, the inverter and integrator circuits were collected, their modeling and research were carried out. As a result, a generator model with characteristics corresponding to the real characteristics of the precision GS-50 signal generator was obtained

    Overexpression of hepatic prothymosin alpha, a novel marker for human hepatocellular carcinoma.

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    Identification of gene products exclusively or abundantly expressed in cancer may yield novel tumour markers. We recently isolated a number of cDNA clones, including alpha-prothymosin, from rat hepatocellular carcinoma (HCC) using a subtraction-enhanced display technique. Alpha-Prothymosin is involved in cell proliferation and is regulated by the oncogene c-myc in vitro. In the present study, we analysed alpha-prothymosin gene expression and its correlation with c-myc in patients with HCC, cirrhosis and adenoma and in normal controls. Hepatic alpha-prothymosin messenger RNA (mRNA) levels were two- to 9.2-fold higher in tumoral tissues than in adjacent non-tumoral tissues in 14 of 17 patients with HCC, regardless of coexisting cirrhosis and viral hepatitis. No marked difference in alpha-prothymosin mRNA levels was present in patients with adenoma and hepatic cirrhosis and in healthy controls. The c-myc mRNA amounts were two- to fivefold increased in 11 of 17 patients with HCC and correlated significantly with those of alpha-prothymosin (P < 0.001). In situ hybridization revealed that increased alpha-prothymosin mRNA was localized in the tumour nodules of the patients with HCC. These data suggest that overexpression of alpha-prothymosin in HCC patients, correlated with c-myc, is possibly involved in the tumorigenic process and may be a novel molecular marker for human HCC

    The influence of rice husk ash addition on the properties of metakaolin-based geopolymers

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    This paper investigates the replacement of metakaolin (MK) with rice husk ash (RHA) in the production of alkali-activated binders or geopolymers. The influence of the RHA addition on compressive and flexural strength, as well as water absorption and apparent porosity were determined, in terms of the percentage of RHA in the mixture and molar ratios of the mixes. Fourier Transform Infrared (FTIR) spectroscopy and Energy Dispersive spectroscopy (EDS) were carried out to assess the changes in the microstructure of the geopolymer matrices with the RHA addition. Results have shown that RHA may be a supplementary precursor for geopolymers. The composition of the geopolymer matrices containing 0-40% RHA is very similar, which indicates that the additional Si provided by RHA is not incorporated to the geopolymer matrix. In addition, geopolymers with RHA content higher than 40% present a plastic behavior, characterized by extremely low strength and high deformation, which can be attributed to the formation of silica gel in formulations containing variable Si/Al ratio

    Коррекция состояния иммунной системы крыс с адъювантным артритом введением липидной фракции плаценты

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    Введення ліпідної фракції плаценти, отриманої методом кріогенного молекулярного фракціонування, на фоні розвитку ад’ювантного артриту оказує корегуючий вплив у відношенні як вмісту, так і функціональної активності регуляторних Т-клітин регіональних лімфовузлів, що призводить до зниження інтенсивності клінічних ознак захворювання.Injection of placental lipid fraction obtained by cryogenic molecular fractionation method on the background of adjuvant arthritis development has a correcting influence in relation to both content and functional activity of regulatory T-cells of regional lymph nodes which leads to a decrease in intensity of clinical signs of the disease
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