703 research outputs found
Tight gas sands permeability estimation from mercury injection capillary pressure and nuclear magnetic resonance data
There are several methods to estimate permeability from pore throat sizes and NMR T2 relaxation time. Although most of the methods are well-established and work well for conventional reservoirs they fail to estimate permeability for tight gas sands. The aim of this study was to establish relationships between permeability and pore throat sizes, derived from mercury injection analysis, and NMR T2 relaxation time. Regression analysis was used to achieve a set of relationships between dry gas permeability, porosity and pore throat sizes for 50 tight gas sand samples. Unlike for normal sandstone, pore throat radii corresponding to a mercury saturation of 10% (r10) is the best permeability predictor for tight gas sands. For tight gas sands, NMR T2 relaxation spectra fall on the shorter values corresponding to the smaller pores. This is because pore spaces are significantly reduced both in size and volume due to extensive compaction and cementation. This study shows that using NMR T2peak and multi-regression analysis, permeability can be estimated with high accuracy even in rocks with substantially constricted pore throats
Parasitic infection in Hemiculter lucisculus, Liza auratus and Gasterosteus aculeatus of the Zardi River (Mazandaran)
A total of 76 specimens of three fish species including: Hemiculter lucisculus (41), Liza auratus (16) and Gasterosteus aculeutus (19) were caught using handnet from 3 station in Zardi River in the south-eastern costal of Caspian Sea at autumn and winter 2009 and spring 2010. The fishes were transported alive to the laboratory of Shahid Rajaee Site. They were killed by cutting their spinal cord and their length and weight were measured. The eye, skin, gill, digestive system, muscle and other organism's of the specimens were examined for parasite infestation. Thirteen parasites species were identified. Ichthyobodo necator was collected from skin of Hemiculter lucisculus and Liza auratus. Ichthyophthirius multifiliis was collected from skin or branchia of Liza auratus and Gasterosteus aculeutus, Chilodonella sp. was collected from skin of Gasterosteus aculeutus, Trichodina sp. from skin and branchia of Hemiculter lucisculus, Liza auratus and Gasterosteus aculeutus, Tetrahymena sp. was collected from skin of Gasterosteus aculeutus , Myxobolus sp. from branchia of Hemiculter lucisculus, Dactylogyrus sp. from branchia of Hemiculter lucisculus and Gasterosteus aculeutus, Gyrodactylus sp. from skin or branchia of Gasterosteus aculeutus, Discocotyle sp. and Diplozoon sp. from branchia of Hemiculter lucisculus, Diplostomum spathaceum from eyes of Hemiculter lucisculus, Saccocoelium obseum from intestine of Liza auratus and Corynosoma stromosum from abdominal cavity of Gasterosteus aculeutus. In present study Hemiculter lucisculus was as a new host for Ichthyobodo necator, Myxobolus sp., Discocotyle sp. and Diplozoon sp. also except Saccocoelium obseum from Liza auratus and Corynosoma stromosum from Gasterosteus aculeatus, the other parasites were reported for the first time in Iran
Metal concentrations in razor clam Solen dactylus (Von Cosel, 1989) (Bivalvia: Solenidae), sediments and water in Golshahr coast of Bandar Abbas, Persian Gulf
In a complementary field study, the concentrations of some metals (Cu, Ag, Pb, Zn, Ni, Co, Mn, Fe, As, Cd, Cr, Mg and Ba) were measured in clam Solen dactylus, sediments and water collected at two stations (Park-e-Qadir, 56° 20/ E, 27° 11/ and Nakhl-e-Nakhoda, 56° 23/ E, 27° 10/ N) of Bandar Abbas coastal waters of the Persian Gulf in November 2008 and February 2009 showing different contamination levels. Although there is little information on metal concentrations in macro-benthic animals in this area, this study, for the first time, reports the accumulation of some metals in S. dactylus in order to introduce this species as a bioindicator for this area. Results indicated that Mg and Fe were the two most abundant metals in clams and sediments. The maximum and minimum metal concentrations in clams belonged to Mg (3850-5040 µgg-1 dry wt) and Ag (0.30-0.40-0.58 µgg-1 dry wt), respectively. There was a significant relationship between the accumulation of metals in clams, sediment and water samples. A significant relationship between clam lengths and concentrations of Cu (positive) and Mg (negative) were observed. Our study also showed that variable metal concentrations were related to different sampling stations, seasons and their interactions as well. Bioaccumulation of metals in clams was significantly different for eight metal elements between start of the gametogenesis and ripeness stages. Our investigation indicated that the clam S. dactylus could be a useful bioindicator for Zinc
Synthesis and Optimization of Reversible Circuits - A Survey
Reversible logic circuits have been historically motivated by theoretical
research in low-power electronics as well as practical improvement of
bit-manipulation transforms in cryptography and computer graphics. Recently,
reversible circuits have attracted interest as components of quantum
algorithms, as well as in photonic and nano-computing technologies where some
switching devices offer no signal gain. Research in generating reversible logic
distinguishes between circuit synthesis, post-synthesis optimization, and
technology mapping. In this survey, we review algorithmic paradigms ---
search-based, cycle-based, transformation-based, and BDD-based --- as well as
specific algorithms for reversible synthesis, both exact and heuristic. We
conclude the survey by outlining key open challenges in synthesis of reversible
and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table
A Method to Relate the Affecting Parameters and Estimate Dilution in Coal Mines
This study provides an overview of the various issues influencing Out-of-Seam Dilution (OSD) in longwall mining method. The collected data has been statistically analyzed to examine the effect of the some factors causing OSD in front of the longwall mining face. Multiple parameter regression analysis was conducted on affecting parameters and the OSD. The SPSS (Statistics Package for Social Sciences) for Windows software package was used for the statistics analysis. Finally, a relationship between affecting parameters and the OSD is established by using the multiple parameter regression results. Results of this study have revealed that depth of seam, dip of seam, roof quality and variation in seam thickness are the most important influence factors for OSD. The proposed method may be utilized for the estimation of OSD for similar mines since, it was based on actual collected data from the coal mines
Deep XMM-Newton observations of the northern disc of M31. I. Source catalogue
We carried out new observations of two fields in the northern ring of M31
with XMM-Newton with two exposures of 100 ks each and obtained a complete list
of X-ray sources down to a sensitivity limit of ~7 x 10^34 erg s^-1 (0.5 - 2.0
keV). The major objective of the observing programme was the study of the hot
phase of the ISM in M31. The analysis of the diffuse emission and the study of
the ISM is presented in a separate paper. We analysed the spectral properties
of all detected sources using hardness ratios and spectra if the statistics
were high enough. We also checked for variability. We cross-correlated the
source list with the source catalogue of a new survey of the northern disc of
M31 carried out with Chandra and Hubble (Panchromatic Hubble Andromeda
Treasury, PHAT) as well as with other existing catalogues. We detected a total
of 389 sources, including 43 foreground stars and candidates and 50 background
sources. Based on the comparison to the Chandra/PHAT survey, we classify 24
hard X-ray sources as new candidates for X-ray binaries (XRBs). In total, we
identified 34 XRBs and candidates and 18 supernova remnants (SNRs) and
candidates. Three of the four brightest SNRs show emission mainly below 2 keV,
consistent with shocked ISM. The spectra of two of them also require an
additional component with a higher temperature. The SNR [SPH11] 1535 has a
harder spectrum and might suggest that there is a pulsar-wind nebula inside the
SNR. We find five new sources showing clear time variability. We also studied
the spectral properties of the transient source SWIFT J004420.1+413702, which
shows significant variation in flux over a period of seven months (June 2015 to
January 2016) and associated change in absorption. Based on the likely optical
counterpart detected in the Chandra/PHAT survey, the source is classified as a
low-mass X-ray binary.Comment: Accepted for publication in A&
Corrigendum to: �Experimental study of prosthesis modifications based on passive dynamic walking model: A limit cycle stability analysis�. J. Biomech. 104 (2020) 109743 (Journal of Biomechanics (2020) 104, (S0021929020301597), (10.1016/j.jbiomech.2020.109743))
The authors regret an error and wish to make the following correction to their recently published paper Moradi et al. (2020): In the results section, an error occurred in part B of Table 2; where the descriptive results of step length were reported incorrectly the same as part A. The corrected table is presented below. © 2020 Elsevier Lt
Study of the radiation damage caused by ion implantation in ZnO and its relation to magnetism
Defects play an important role in causing room temperature ferromagnetism in ZnO films. Multi-energy ion implantation has been employed to introduce different concentrations of non-magnetic ions, including argon, arsenic and krypton, into high-quality ZnO films and room temperature ferromagnetism has been observed for As and Kr implanted ZnO while none was observed for Ar doped films. The Monte Carlo simulation code SRIM was adopted to simulate the distributions of the implanted ions, the induced zinc and oxygen vacancies and the resulting interstitials. A common radiation damage parameter, known as the atomic displacements per atom (dpa), was calculated to quantify the primary radiation damage production. Our results show that the observed magnetic moment measured at low temperatures due to implantation with a given ion is proportional to the dpa. The constant of proportionality between the magnetism and the dpa depends on the implanted ion. This constant is largest for heavy, large ions. To obtain room temperature d0 magnetism in ZnO, non-magnetic ions with high mass are suggested to be implanted into ZnO films
Rocker outsole shoes and margin of stability during walking: a preliminary study
Rocker outsole shoes are commonly prescribed to diabetic patients to redistribute peak plantar pressures at high risk areas such as forefoot thereby decreasing risks of plantar ulceration. However, there are evidences of postural destabilizing effect of the rocker outsole shoes. Patients with diabetes, particularly those suffering from neuropathy, are at a higher risk of falling. Then, beside primary role of rocker outsole in offloading, it is essential to explore the effect of the rocker outsole on postural stability of these patients. The smaller base of support (BOS) of the rocker outsoles due to their specific geometry has been previously mentioned as a threat to postural stability. Margin of stability (MOS) appeared to be an appropriate method for measuring postural stability during walking by considering the dynamicity of BOS in its equation. MOS is defined as the distance between the velocity adjusted position of the centre of mass (COM) and the boundaries of the BOS which constantly changes during walking. Then, this study proposes how we can use MOS concept to investigate the impact of the rocker outsoles on dynamic stability. In this study the kinematic data from a single subject with diabetic neuropathy was used to explain the efficiency of the methodology. Conclusive results are expected after carrying out systematic tests using a statistically representative sample size.This project is funded by Iran University of Medical Sciences (IR.IUMS.REC. 1395.9211503202).info:eu-repo/semantics/publishedVersio
Geographical and socioeconomic inequalities in female breast cancer incidence and mortality in Iran: A Bayesian spatial analysis of registry data
Background
In Iran, trends in breast cancer incidence and mortality have generally been monitored at national level. The purpose of this study is to examine province-level disparities in age-standardised breast cancer incidence versus mortality from 2000 to 2010 and their association with socioeconomic status.
Methods
In this study, data from Iran’s national cancer and death registry systems, and covariates from census and household expenditure surveys were used. We estimated the age-standardised incidence and mortality rates in women aged more than 30 years for all 31 provinces in the consecutive time intervals 2000–2003, 2004–2007 and 2008–2010 using a Bayesian spatial model.
Results
Mean age-standardised breast cancer incidence across provinces increased over time from 15.0 per 100,000 people (95% credible interval 12.0,18.3) in 2000–2003 to 39.6 (34.5,45.1) in 2008–2010. The mean breast cancer mortality rate declined from 10.9 (8.3,13.8) to 9.9 (7.5,12.5) deaths per 100,000 people in the same period. When grouped by wealth index quintiles, provinces in the highest quintile had higher levels of incidence and mortality. In the wealthiest quintile, reductions in mortality over time were larger than those observed among provinces in the poorest quintile. Relative breast cancer mortality decreased by 16.7% in the highest quintile compared to 10.8% in the lowest quintile.
Conclusions
Breast cancer incidence has increased over time, with lower incidence in the poorest provinces likely driven by underdiagnoses or late-stage diagnosis. Although the reported mortality rate is still higher in wealthier provinces, the larger decline over time in these provinces indicates a possible future reversal, with the most deprived provinces having higher mortality rates. Ongoing analysis of incidence and mortality at sub-national level is crucial in addressing inequalities in healthcare systems and public health both in Iran and elsewhere
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