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H. It (h + it)
Selected AbstractsImpact of the Sampling Rate on the Estimation of the Parameters of Fractional Brownian MotionJOURNAL OF TIME SERIES ANALYSIS, Issue 3 2006Zhengyuan Zhu Primary 60G18; secondary 62D05, 62F12 Abstract., Fractional Brownian motion is a mean-zero self-similar Gaussian process with stationary increments. Its covariance depends on two parameters, the self-similar parameter H and the variance C. Suppose that one wants to estimate optimally these parameters by using n equally spaced observations. How should these observations be distributed? We show that the spacing of the observations does not affect the estimation of H (this is due to the self-similarity of the process), but the spacing does affect the estimation of the variance C. For example, if the observations are equally spaced on [0, n] (unit-spacing), the rate of convergence of the maximum likelihood estimator (MLE) of the variance C is . However, if the observations are equally spaced on [0, 1] (1/n -spacing), or on [0, n2] (n -spacing), the rate is slower, . We also determine the optimal choice of the spacing , when it is constant, independent of the sample size n. While the rate of convergence of the MLE of C is in this case, irrespective of the value of ,, the value of the optimal spacing depends on H. It is 1 (unit-spacing) if H = 1/2 but is very large if H is close to 1. [source] Daytime variations of interleukin-1, in gingival crevicular fluidEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2008Angela Bergmann Interleukin-1, (IL-1,) is an important parameter in periodontal research because of its role in inflammation and bone resorption. One measure used to assess local IL-1, concentrations is analysis of its levels in gingival crevicular fluid (GCF). While studies on serum IL-1, concentrations indicate a circadian rhythm of this parameter, nothing is known about daytime variations of IL-1, in GCF. The present study thus aimed to analyse such variations. Daytime variations of GCF-IL-1, between 08:00 and 22:00 h were assessed, with a time resolution of 2 h, in 28 periodontally healthy subjects. The data showed a significant variation throughout the day, with the lowest concentrations and total amounts in the morning and the highest in the evening. The effect sizes of comparisons between morning and evening samples were medium to high and corresponded in magnitude to those reported in other published research comparing healthy sites and those affected by periodontitis. The smallest daytime variations were found to occur between 12:00 h and 18:00 h. It is concluded that daytime variations in GCF-IL-1, are large enough to be able to mimic or mask differences caused by clinical factors. [source] Removal of Cadmium and Lead from Aqueous Solution by,Enterococcus faecium,StrainsJOURNAL OF FOOD SCIENCE, Issue 1 2010A. Topcu ABSTRACT:, Foods may be contaminated with heavy metals, which, even in small quantities, possess detrimental effects on human health. The aim of the present study was to investigate the uptake of cadmium or lead from an aqueous medium frequently found in foods, by 2,Enterococcus faecium,strains (E. faecium,EF031 and,E. faecium,M74). Also, the effects of the bacterial viability, incubation (contact) time, and pH on the binding capacities and binding stability were assessed. The results showed that both of the strains efficiently removed cadmium and lead. While EF031 removed 77.3% to 98.1% of cadmium and 66.9% to 98.9% of lead, M74 removed 53.5% to 91% of cadmium and 42.9% to 93.1% of lead throughout a 48 h incubation period at pH 5. It was found that, at 1 h, EF031 and M74 strains removed cadmium and lead, which was more than 60% of total removed cadmium and lead throughout the whole incubation period of 48 h. It suggests that the uptake of cadmium and lead by EF031 and M74 strains is a rapid process. The binding of both heavy metals increased with increasing pH of an aqueous medium and was the highest at pH 5. Also, the complexes formed between both heavy metals and bacterial cells were found to be stable. These findings indicate that,E. faecium,strains used in the study are able to bind the 2 heavy metals and may be used in the production of fermented functional foods, which will be healthy via its detoxification properties. [source] Short-term homeostasis of REM sleep assessed in an intermittent REM sleep deprivation protocol in the ratJOURNAL OF SLEEP RESEARCH, Issue 1 2002ADRIÁN OCAMPO-GARCÉS An intermittent rapid eye movement (REM) sleep deprivation protocol was applied to determine whether an increase in REM sleep propensity occurs throughout an interval without REM sleep comparable with the spontaneous sleep cycle of the rat. Seven chronically implanted rats under a 12 : 12 light,dark schedule were subjected to an intermittent REM sleep deprivation protocol that started at hour 6 after lights-on and lasted for 3 h. It consisted of six instances of a 10-min REM sleep permission window alternating with a 20-min REM sleep deprivation window. REM sleep increased throughout the protocol, so that total REM sleep in the two REM sleep permission windows of the third hour became comparable with that expected in the corresponding baseline hour. Attempted REM sleep transitions were already increased in the second deprivation window. Attempted transitions to REM sleep were more frequent in the second than in the first half of any 20-min deprivation window. From one deprivation window to the next, transitions to REM sleep changed in correspondence to the amount of REM sleep in the permission window in-between. Our results suggest that: (i) REM sleep pressure increases throughout a time segment similar in duration to a spontaneous interval without REM sleep; (ii) it diminishes during REM sleep occurrence; and (iii) that drop is proportional to the intervening amount of REM sleep. These results are consistent with a homeostatic REM sleep regulatory mechanism that operates in the time scale of spontaneous sleep cycle. [source] Low-Loss Microwave Dielectrics in the (Mg1,xZnx)2TiO4 CeramicsJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2008Cheng-Liang Huang The microwave dielectric properties and the microstructures of (Mg1,xZnx)2TiO4 ceramics prepared by the conventional solid-state route were investigated. Lattice parameters were also measured for samples with different x. As x increased from 0 to 0.05, the Q×f of the specimen can be promoted from 150 000 GHz to a maximum 275 300 GHz. It also showed a remarkable lowering in the sintering temperature (,100°C). Ilmenite-structured (Mg0.95Zn0.05)TiO3 was detected as a second phase. The coexistence of the second phase, however, is not harmful to the dielectric properties of the specimen because it possesses compatible ones. A fine combination of microwave dielectric properties (,r,15.48, Q×f,275 300 GHz, ,f,,34 ppm/°C) was obtained for (Mg0.95Zn0.05)2TiO4 specimen sintered at 1330°C for 4 h. It is proposed as a very promising dielectric material for low-loss microwave and millimeter wave applications. [source] Scanning electron microscopy investigations on bis(2-ethylhexyl)phthalate treated Mycobacterium cellsMICROSCOPY RESEARCH AND TECHNIQUE, Issue 8 2006B. Angelova Abstract Comparative investigation of steroid transforming activity and ultrastructural changes of bis(2-ethylhexyl)phthalate (BEHP, phthalate) treated Mycobacterium sp. NRRL B-3805 cells was carried out. Transformation of ,-sitosterol into androstenedione (AD) and androstadienedione (ADD) was performed in phthalate medium by resting cells preincubated in the organic solvent for a period from 3 to 24 h. It was observed that a preincubation greater than 12 h leads to the development of dense formations on the cells surface, reduction in the cell turgor, disruption in the cell walls, and formation of zones with reduced electron density. The preincubation for 24 h causes deeper changes in the cell ultrastructure but the treated cells retain their steroid transforming activity, allowing up to 80% of the substrate to be converted into AD and ADD. A preincubation of the resting Mycobacterium cells in BEHP for 6 h might be recommended as it leads to an achievement of stoichiometrical transformation of the substrate into AD and ADD and slightly higher initial rate of the reaction performed. Microsc. Res. Tech., 2006. © 2006 Wiley-Liss, Inc. [source] The novel herbicide oxaziclomefone inhibits cell expansion in maize cell cultures without affecting turgor pressure or wall acidificationNEW PHYTOLOGIST, Issue 2 2005Nichola O'Looney Summary ,,Oxaziclomefone [OAC; IUPAC name 3-(1-(3,5-dichlorophenyl)-1-methylethyl)-3,4-dihydro-6-methyl-5-phenyl-2H -1,3-oxazin-4-one] is a new herbicide that inhibits cell expansion in grass roots. Its effects on cell cultures and mode of action were unknown. In principle, cell expansion could be inhibited by a decrease in either turgor pressure or wall extensibility. ,,Cell expansion was estimated as settled cell volume; cell division was estimated by cell counting. Membrane permeability to water was measured by a novel method involving simultaneous assay of the efflux of 3H2O and [14C]mannitol from a ,bed' of cultured cells. Osmotic potential was measured by depression of freezing point. ,,OAC inhibited cell expansion in cultures of maize (Zea mays), spinach (Spinacia oleracea) and rose (Rosa sp.), with an ID50 of 5, 30 and 250 nm, respectively. In maize cultures, OAC did not affect cell division for the first 40 h. It did not affect the osmotic potential of cell sap or culture medium, nor did it impede water transport across cell membranes. It did not affect cells' ability to acidify the apoplast (medium), which may be necessary for ,acid growth'. ,,As OAC did not diminish turgor pressure, its ability to inhibit cell expansion must depend on changes in wall extensibility. It could be a valuable tool for studies on cell expansion. [source] Tadalafil as an in vitro sperm motility stimulantANDROLOGIA, Issue 1 2007T. Mostafa Summary Tadalafil (Cialis®) is a known oral selective phosphodiesterase-5 inhibitor used widely in the management of erectile dysfunction. To assess its ability on human sperm motility in vitro, 70 asthenozoospermic semen specimens delivered by masturbation were investigated. Semen samples were divided equally into four tubes, one as a control and to the others tadalafil dissolved solution was added in vitro in three different concentrations (4.0, 1.0, 0.5 mg ml,1 respectively). The tubes were incubated and were followed up for sperm motility per cent changes for 0.5, 1, 2, 3 h. It was found that the concentration used played an important role in the degree of sperm enhancement. Specimens treated with 4 mg ml,1 tadalafil solution demonstrated a significant decrease in sperm motility compared with the controls. Specimens treated with 1.0 mg ml,1 solution demonstrated significant increase in sperm progressive forward motility. Specimens treated with 0.5 mg ml,1 solution demonstrated significant increases in sperm motility but lower than that of 1 mg ml,1 concentration. It is concluded that in vitro use of tadalafil solution in special concentration has a significant stimulatory effect on asthenozoospermic sperm motility. [source] Duration of estrus induced after GnRH-PGF2, protocol in dairy heiferANIMAL SCIENCE JOURNAL, Issue 6 2009Chikako YOSHIDA ABSTRACT Estrous expressions in dairy cows have been shortened and weakened. Dairy heifers, on the other hand, may not have had such changes in estrous signs as observed in cows, since they have less stresses than cows. The aim of this study was to describe the duration of estrus in a herd of dairy heifers. A total of 56 Holstein Friesian heifers estrus was synchronized using two different hormonal protocols. They were checked for primary and secondary estrous signs with the help of heat detection devices for 48 h at an interval of 4 h starting at 16.00 hour, one day after PGF2, treatment. Onset and end of standing estrus during 48 h observation period was recorded in 35 of the 44 heifers coming into estrus within 5 days after PGF2, treatment during the observation period. The duration of standing estrus on the average (±SD) was 9.7 ± 5.3 h. Percentage of heifers with standing estrus longer than 12 h was 40%, and 53% showed standing estrus only for 4,8 h. It is indicated that duration of estrus in dairy heifers has been shortened recently. [source] Application of magnetic force-based cell patterning for controlling cell,cell interactions in angiogenesisBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2009Kosuke Ino Abstract To investigate the effects of cell,cell interactions on cellular function, the microenvironment surrounding cells should be precisely controlled. Here, we describe a cell patterning technique, which utilizes magnetic force and magnetite nanoparticles. This method was used to develop cell culture arrays for investigation of cell behaviors in angiogenesis. Pin holder devices that contain more than 6,000 pillars on the surface are used for fabricating the cell culture arrays by setting it on a magnet. The magnetically labeled cells were arranged by magnetic distribution. When the human umbilical vein endothelial cells are arranged at 250 µm intervals (5.9 cells/spot), the cells spread toward other cell cluster on adjacent spots in 4.5 h, and formed cord-like structures in 8.5 h. It was shown that cell,cell interactions were successfully investigated using magnetic cell arrangement. Biotechnol. Bioeng. 2009; 102: 882,890. © 2008 Wiley Periodicals, Inc. [source] Influence on antiproliferative activity of structural modification and conjugation of gonadotropin-releasing hormone (GnRH) analoguesCELL PROLIFERATION, Issue 5 2000A. Kálnay Abstract The effect of various GnRH analogues, and their conjugates on proliferation, clonogenicity and cell cycle phase distribution of MCF-7 and Ishikawa human cancer cell lines was studied. GnRH-III, a sea lamprey GnRH analogue reduced cell proliferation by 35% and clonogenicity by 55%. Structural modifications either decreased, or did not alter biological activity. Conjugation of GnRH analogues including MI-1544, MI-1892, and GnRH-III with poly(N-vinylpyrrolidone-co-maleic acid) (P) through a tetrapeptide spacer GFLG(X) substantially increased the inhibitory effect of the GnRH analogues. The conjugate P-X-GnRH-III induced significant accumulation of cells in the G2/M phase; from 8% to 15.6% at 24 h and 9.8% to 15% at 48 h. It was concluded that conjugation of various GnRH analogues substantially enhanced their antiproliferative activity, strongly reduced cell clonogenicity and retarded cell progression through the cell division cycle at the G2/M phase. [source] | |||||||||||||