919 research outputs found
Some asymptotic stationary point theorems in topological spaces
AbstractIn this paper, we present some asymptotic stationary point results for topological contraction mappings by relaxing the compactness of the space. Moreover, some classes of topological contractions are characterized
Short communication: Population genetic structure studies of Liza aurata based on mtDNA control region sequences analyses in the southern coasts of the Caspian Sea
Nowadays many species are endangered as a result of habitat loss. Decreases in population lead to reduced genetic diversity, which can cause survival crisis in a population (Cecconi et al., 1995). Nowadays optimal management of fish stocks needs information on population structure of species that is provided to researchers through genetic science. Bereavement of science about stock composition will lead to the fracture of fisheries management and unsuitable harvest of stocks (Papasotiropoulos et al., 2007). One of the beneficial methods to demonstrate genetic diversity is haplotype analysis of the D-loop region, an index which is very important and determinant for the preservation of species. Significant genetic variation is found in the D-loop region, even among individuals within a given species. Grey mullets are not endemic species of the Caspian Sea. Juveniles of L. aurata, L. saliens and Mugil cephallus were introduced from the Black Sea into the Caspian Sea during the years 1930-1934. But only the introduction of L. aurata and L. saliens was successful and they adapted well to the ecological conditions of the Caspian Sea (Fazli et al., 2008)
Concurrence distribution in excited states of the 1D spin-1/2 transverse field XY model: two different regions
We investigate the variation of concurrence in a spin-1/2 transverse field XY
chain system in an excited state. Initially, we precisely solve the eigenvalue
problem of the system Hamiltonian using the fermionization technique.
Subsequently, we calculate the concurrence between nearest-neighbor pairs of
spins in all excited states with higher energy than the ground state. Below the
factorized field, denoted as , we find no pairwise
entanglement between nearest neighbors in excited states. At the factorized
field, corresponding to a factorized state, we observe weak concurrence in very
low energy states. Beyond , the concurrence strengthens, entangling all
excited states. The density of entangled states peaks at the center of the
excited spectrum. Additionally, the distribution of concurrence reveals that
the midpoint of the non-zero concurrence range harbors the most entangled
excited states.Comment: 8 pages, 3 figure
Comparison of (Th-U-233) O-2 and (Th-U-235) O-2 fuel burn up into a thermal research reactor using MCNPX 2.6 code
Gholamzadeh, Z (Gholamzadeh, Z); Tenreiro, C (Tenreiro, C.). Talca Univ, Dept Phys, Talca, Chile.Background: Decrease of economically accessible uranium resources motivates consideration of breeding of fertile elements such as thorium. Material and Method: Thorium oxide fuel burn up calculation of a simulated research reactor cooled heavy water has been proposed in the present work using MCNPX 2.6 code. Two U-233 and U-235 isotopes have been used as fissile element of thorium oxide fuel. Xe-135 and Sm-149 reactivity variations has been studied in the core loaded (Th-U-233)O-2 or (Th-U-235)O-2 fuel matrixes during 3 months burn up process. Results: Thorium oxide having 4% U-233 burned 1 MW power results in less Sm-149 reactivity than thorium oxide having 4% U-235 burned in 0.5 MW power. Xe-135 reactivity has an overestimated shift by 15 days in the core operated in 0.5 MW than the other, after 15 days both the cores behave similarly. 480 g of U-235 burns into the core using 0.5 MW power and 364 g of U-233 invents after 3 months. Burn up calculation of the modeled core of (Th-U-233)O-2 fuel shows a fissile mass reduction by 60 days while the consumed fissile mass reaches to its initial value after 120 days. The core flux is constant during 3 months for both modeled cores. A considerable negative reactivity occurs up to 15 days in both cores which can be refer to xenon inventory during thistime and then neutron multiplication factor is steadier up 3 months. Conclusion: Breeder thorium fuel enriched U-233 make several advantages of good neutronic economy, U-233 inventory and less inventory of long-lived alpha emitter waste
Population genetic studies of Liza aurata using D-Loop sequencing in the southeast and southwest coasts of the Caspian Sea
Genetic diversity as an important marker of the ecological status of aquatic ecosystems is considered a unique and powerful tool to evaluate biological communities. In order to evaluate the genetic diversity among golden mullet species (Liza aurata) in the southeast and southwest coasts of the Caspian Sea by D-Loop gene sequencing, a total of 23 fin specimens of golden mullet were collected from the Gilan (Anzali area) and Golestan (Gomishan area) provinces. Total DNA from the samples was extracted by ammonium acetate method and the quality and quantity of the extracted DNA were assessed by spectrophotometry and electrophoresis. Polymerase Chain Reaction (PCR) was conducted on the target DNA and then DNA sequencing was carried out. D-loop region in mitochondrial DNA (mtDNA) of golden mullet contained 900 base pairs (bp). Phylogenetic relationships among golden mullet were calculated by MEGA software version 5.05 and divergence time was estimated using Tahjima's test. The results obtained from this study revealed that there were high genetic differences among two regions in the Gilan and Golestan provinces. Kimura 2-parameter was used for genetic distance analysis and the genetic distance recorded between Gilan and Golestan Provinces was calculated at 0.259. The high levels of FsT were observed between Gilan and Golestan Provinces which indicates that genetic differences exist among present populations (p≤.05). Based on the results obtained from the south Caspian Sea, probably two different populations of Liza aurata are living in the Gilan and Golestan Provinces
Multibody expansion of the local integrals of motion: How many pairs of particle-hole do we really need to describe the quasiparticles in the many-body localized phase?
The emergent integrability in a many-body localized (MBL) system can be well
characterized by the existence of the complete set of local integrals of motion
(LIOMs). Such exactly conserved and exponentially localized operators are often
understood as quasiparticle operators which can be expanded in terms of
single-particle operators dressed with different numbers of particle-hole
pairs. Here, we consider a one-dimensional XXZ spin- Heisenberg chain
in the presence of a random field and try to quantify the corrections needed to
be considered in the picture of quasiparticles associated with LIOMs due to the
presence of particle-hole excitations. To this end, we explicitly present the
multibody expansion of LIOM creation operators of the system in the MBL regime.
We analytically obtain the coefficients of this expansion and discuss the
effect of higher-order corrections associated with different numbers of
particle-hole excitations. Our analysis shows that depending on the
localization length of the system, there exist a regime in which the
contributions that come from higher-order terms can break down the effective
one-particle description of the LIOMs and such quasiparticles become
essentially many-body-like
Species identification reveals mislabeling of important fish products in Iran by DNA barcoding
This study reports on the molecular identification of fish species from processed products which had a priori been classified as belonging to 5 important species in Iran for human consumption. DNA barcoding using direct sequencing of an approximately 650bp of mitochondrial Cytochrome oxidase subunit I (COI) gene revealed incorrect labeling of Narrow-barred Spanish mackerel samples. High occurrence of fraudulent fishery products, if left unchecked, can pose a negative impact on the economy. This investigation adds further concern on the trading of processed fish products in Iran from both health and conservation points of view
Evaluation of different dietary protein and energy levels on growth performance and body composition of narrow clawed crayfish (Astacus leptodactylus)
Nine practical diets containing increasing percentages of crude protein (CP) and energy (30%, 35%, 40% and 300kcal/100g, 370kcal/100g and 450kcal/100g) were fed to narrow clawed crayfish (mean individual weight=17±2.3 g) during an 8 week feeding trial. Weight Gain, Feed conversion ratio (FCR), Protein Efficiency Ratio (PER), Net Protein Utilization (NPU), Daily Food Consumption (DFC) and body composition of tail-muscle meat of narrow clawed crayfish were determined. At the conclusion of the experiment, comparing the growth parameters in response to interaction between protein and energy levels demonstrated that dietary number 2 (30/370) resulted in higher WG, NPU, PER, and the lowest FCR whereas dietary number 3 (30:450) showed higher SGR and DFC. Comparison of the body composition results indicates the greatest amount of protein absorption in diet number 2 (30/370). Results from this study indicate that narrow clawed crayfish can be fed a practical diet containing 30% protein and 370 Kcal/100gr. Reducing CP levels in narrow clawed crayfish diets may help reduce operating costs and thereby increase producers’ profits
A Simple Hybrid Approach for the Synthesis of Heat Exchanger Networks Involving Internal Utility Exchangers
This study aims to present a simple hybrid approach for synthesizing heat exchanger networks (HENs). The synthesis of HEN structures employs a genetic algorithm based on a modified node representation, closely resembling the stage-wise superstructure model. This modified representation allows for addressing the internal utility exchangers throughout the entire network. Despite the nonlinear nature of the model governing the continuous variables of each structure, a relatively simple linear formulation is developed to handle these variables. This novel formulation comprises a linear programming model for maximum energy recovery, a linear correction procedure (COP), and two search loops. The COP focuses on determining the optimal values of exchangers’ heat loads and stream split ratios to reach the minimum total annual cost of the network. The study investigates four extensively studied medium- to large-scale networks from the literature. Despite the simplicity of the proposed approach, a comparison of results demonstrates its potential effectiveness
The Serum Changes of Neuron-Specific Enolase and Intercellular Adhesion Molecule-1 in Patients With Diffuse Axonal Injury Following Progesterone Administration: A Randomized Clinical Trial
Background: Improvement of neurologic outcome in progesterone-administered patients with diffuse axonal injury (DAI) has been found in a recent study. Also, there has been interest in the importance of serum parameters as predictors of outcome in traumatic brain injury.
Objectives: The aim of this study was to examine the effect of progesterone administration on serum levels of neuron-specific enolase (NSE), and intercellular adhesion molecule-1 (ICAM-1) in clinical DAI.
Patients and Methods: In this study, the serum levels of ICAM-1 and NSE of 32 male DAI patients (18 - 60 years of age, a Glasgow coma scale of 12 or less, and admitted within 4 hours after injury) who were randomized for a controlled phase II trial of progesterone were analyzed. The analysis was performed between the control and progesterone groups at admission time, and 24 hours and six days after DAI, respectively.
Results: A reduction in the serum level of ICAM-1 was noticed in the progesterone group 24 hours after the injury (P < 0.05). There was no significant difference in the serum level of NSE between the study groups during evaluation. At 24 hours after the injury, the level of ICAM-1 in the control group was higher than that at admission time (P < 0.05). The lowest level of NSE in the two groups was seen six days after DAI (P < 0.01).
Conclusions: In summary, progesterone administration reduced serum ICAM-1, and whereby may attenuate blood brain barrier disruption, the latter needs further investigation for confirmation
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