2,065 research outputs found
Comparison of serum levels of hepcidin and pro-hepcidin in hemodialysis patients and healthy subjects
Hepcidin prevents absorption of iron from the intestine and inhibits release of iron from macrophages and hepatocytes. For this reason, it seems that high levels of hepcidin are a predisposing factor for anemia in chronic inflammatory conditions such as chronic kidney disease and dialysis patients. This study was designed to determine the role of changes in the level of serum hepcidin in the management of hemodialysis patients. This study included 44 dialysis patients and 44 controls. The hepcidin and pro-hepcidin levels were measured by the enzyme linked immunosorbent assay method. The serum ferritin level was measured by the chemiluminescence method. The mean hepcidin level was 999.3 ± 996.7 ng/mL in the case group and 770.4 ± 815.9 ng/mL in the control group (P = 0.25). The mean pro-hepcidin level was, respectively, 186.1 ± 220.3 pg/mL and 150.87 ± 207.7 pg/mL, in the case group and control groups (P = 0.45). The mean (standard deviation) ferritin level was 816.4 ± 379.4 ng/mL in the case group and 193 ± 171.8 ng/mL in the control group (P < 0.001). In the case group, the correlation between serum ferritin and hepcidin was not significant (r = 0.6, P = 0.08). Also, there was no significant correlation between serum ferritin and pro-hepcidin levels (r = 0.6, P = 0.08). A positive correlation was seen between pro-hepcidin and hepcidin levels (r = 0.92, P < 0.01). In this study, the results showed that the serum hepcidin levels are high in dialysis patients and that there was no correlation with the serum ferritin levels
Synthesis of Crown Ethers & Stereochemistry of 1, 4-Ditertiarybutyl-1, 4-Dihydronaphthalene
A. Cyclization of ethylene oxide in the presence of transition metal salts was studied. Several reactions with different catalysts were tried and some of these reactions produced compounds which show only one sharp singlet in their NMR spectra. These products were also soluble in benzene. The solubility of potassium permanganate in this mixture suggests the presence of cyclic polyethers. In spite of the above observations, all attempts to liberate cyclic ethers from their metal complexes were unsuccessful.
B. In the second project, the stereochemistry of 1,4-ditertiarybuty1- 1,4-dihydronaphthalene was elucidated using 1H and 13C NMR. For this purpose, other naphthalene and anthracene systems were used as model compounds. For cases in which no model systems were available, the angular dependence of coupling constants was used to estimate the coupling constants. The LAOCOON III computer program was implemented to produce the observed spectrum. It was determined that the dihydrobenzene ring in this molecule is nearly planar
OAM mode selection for high-speed optical communications : a bit loading approach
Occupying more channels increases transmission
rate, however, crosstalk increases to an unacceptable level long
before all 24 channels can be exploited. The crosstalk is not
uniform between modes, hence occupying different subsets of
channels leads to vastly different achievable transmission capacities. In addition to optimizing occupied subsets of channels, we
adopt a bit loading approach.
We examine several resource allocation strategies in a coherent
detection system, starting with typical OAM mode group granularity (all channels in a group occupied) and ending with single
channel granularity. By exhaustive search at mode group granularity, we find a bit load increasing the total capacity by ∼15%
compared to a minimax solution for mode group allocation.
Single channel granularity imposes great computational effort
to optimize bit loading. We propose search algorithms that are
computationally tractable and improve capacity by ∼30% vis-à vis the minimax solution for mode groups. Finally, we examine the
impact of signal-to-noise ratio (SNR) and receiver digital signal
processing (DSP) complexity on the overall capacity. We include
a discussion of DSP with limited or with no multi-input, multioutput (MIMO) processing.Our algorithms could be applied to
any mode multiplexing fiber, as it only relies on knowledge of
the crosstalk matrix across modes
Hemiculter leucisculus (Basilewsky, 1855) and Alburnus caeruleus Heckel, 1843: New data on their distributions in Iran
This paper provides information on the geographic distributions of two cyprinid species: Hemiculter leucisculus (Basilewsky, 1855) and Alburnus caeruleus Heckel, 1843, in the world and the entire drainage systems in Iran. The new distribution records were taken from Maroon River (Jarrahi River system) and Chardaval River (Karkheh river system), both in Tigris River basin showing wide and narrow distribution ranges of these two cyprinid fishes, respectively. The main introduction sites and distribution range of H. leucisculus is the southern parts of the Caspian Sea basin in Iran from where it has probably been translocated to other Iranian basins along with exotic Chinese carps. Although A. caeruleus is native to Tigris River basin, it had been already recorded only from Gamasiab and Doab rivers in 2009 in Karkheh River system (Tigris) and thus the present study extends its distribution range. In case of alien species, human-mediated fish introductions may increase faunal similarity among primary drainages due to a strong tendency for taxonomic homogenization caused primarily by the widespread introduction of cyprinid fishes. Fish faunal homogenization might be highest in drainages (e.g. Caspian Sea and Tigris basins) subjected to the greatest degree of disturbance associated with human settlement, infrastructure and change in land use. The provided data might be used in conservation program of freshwater fishes of Iran
Thermal instability in ionized plasma
We study magnetothermal instability in the ionized plasmas including the
effects of Ohmic, ambipolar and Hall diffusion. Magnetic field in the single
fluid approximation does not allow transverse thermal condensations, however,
non-ideal effects highly diminish the stabilizing role of the magnetic field in
thermally unstable plasmas. Therefore, enhanced growth rate of thermal
condensation modes in the presence of the diffusion mechanisms speed up the
rate of structure formation.Comment: Accepted for publication in Astrophysics & Space Scienc
The algebraic hyperstructure of elementary particles in physical theory
Algebraic hyperstructures represent a natural extension of classical
algebraic structures. In a classical algebraic structure, the composition of
two elements is an element, while in an algebraic hyperstructure, the
composition of two elements is a set. Algebraic hyperstructure theory has a
multiplicity of applications to other disciplines. The main purpose of this
paper is to provide examples of hyperstructures associated with elementary
particles in physical theory.Comment: 13 page
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