Placing Confidence Limits on Polarization Measurements

The determination of the true source polarization given a set of measurements is complicated by the requirement that the polarization always be positive. This positive bias also hinders construction of upper limits, uncertainties, and confidence regions, especially at low signal-to-noise levels. We generate the likelihood function for linear polarization measurements and use it to create confidence regions and upper limits. This is accomplished by integrating the likelihood function over the true polarization (parameter space), rather than the measured polarization (data space). These regions are valid for both low and high signal-to-noise measurements.Comment: 8 pages, 3 figures, 1 table, submitted to PAS

Effect of substrate bias voltage on structural and tribological properties of W-Ti-C-N thin films produced by combinational HiPIMS and DCMS co-sputtering

Protective multi-component thin films at the surface of cutting tools have been significantly developed to reduce wear and friction. The present work investigates the effect of substrate bias voltage on the structural-tribological relations of W-Ti-C-N thin films produced by HiPIMS and DCMS co-sputtering. Chemical analysis of the coatings is obtained and composite phase structure is revealed. Morphology of the coatings illustrates that defectless surfaces may be achieved. Topographical parameters are investigated by employing graphical software. Indentation, scratch and pin-on-disk tests (pin is AISI 52100 steel) are applied to study mechanical behaviors of the films. To produce a wear-resistant film, a median bias voltage ( 60 V) and as a result, optimum content of tungsten concentration (19.2 at. %), grain size (42.8 nm) and average peak interval (188 nm) is required. Finally, a model based on the representative volume element is developed to show crack propagation and delamination.info:eu-repo/semantics/publishedVersio

Rangelands and Pastoralism of the Middle-East and North Africa, from Reality to Dream

The Middle East and North Africa (MENA) is a vast area covering 20 countries from western Asia to North Africa, with nearly 9,000,000 Km2 and 303 million hectares of total rangelands. Rangelands play an essential role in supporting people\u27s livelihoods and food security. Mobile pastoralism is the most viable and resilient form of production and land use in the fragile drylands of MENA. The region\u27s governments have considered mobile pastoralism as backwards mainly because it was difficult to deliver mobile services to them. They designed various policies that were not in harmony with pastoralists\u27 customary rules and norms and severely weakened their mutual aid associations and governance systems for natural resources management. Nowadays, pastoralists\u27 rangelands and customary territories are shrinking, fragmenting, and degrading due to various reasons, but mainly the expansion of agricultural or industrial needs. Based on pastoralists and rangelands\u27 socio-ecological values, the world needs to apply the evidence-based experiences and Indigenous knowledge of pastoralists in preventing rangeland degradation. It is urgent to start a new era for a paradigm-shift for an inclusive interaction, establishing pro-poor livestock policies. These polices would address the barriers and bottlenecks faced by pastoral and agro-pastoral communities, and secure land tenure at community and landscape levels through multi-stakeholder dialogue, including during the International Year of Rangelands and Pastoralists (IYRP). It is time to call for respect of customary governance systems of pastoralists, recognition of their territories as Indigenous and Community Conserved Areas (ICCA1s—territories of life) under various and norms in the region like Qoroq, Hima, Agdal, and any other form of local conservation to prevent fragmentation of pastoralists territories and rangelands degradation leading to desertification

Effect of peak power on microstructure, mechanical and tribological properties of W-Ti-C-N(O) ceramic films produced by hybrid sputtering

This research investigates the impact of peak power (from 44 to 105 kW) on the structural and tribological properties of W-Ti-C-N(O) films. Chemical analysis of the coatings, using energy-dispersive spectroscopy and Raman spectroscopy, indicates that increasing target power results in a rise in the oxygen (from 2.6 to 12.0 at%), carbon (from 19.7 to 32.4 at%), and sp3 (from 9.8% to 24.3%) content. Morphological and topographical analysis reveal that an increase in target power causes a transition from a columnar structure (with nodular grains) to a dense structure (with textured grains). The indentation and dry sliding tests demonstrate that the maximum level of H/E2 (0.00047 GPa-1) is achieved, along with a low wear rate of 8.1 × 10-7 mm3/N.m.info:eu-repo/semantics/publishedVersio

Polarization of Broad Absorption Line QSOs I. A Spectropolarimetric Atlas

We present a spectropolarimetric survey of 36 broad absorption line quasi-stellar objects (BAL QSOs). The continuum, absorption trough, and emission line polarization of BAL QSOs yield clues about their structure. We confirm that BAL QSOs are in general more highly polarized than non-BAL QSOs, consistent with a more equatorial viewing direction for the former than the latter. We have identified two new highly-polarized QSOs in our sample (1232+1325 and 1333+2840). The polarization rises weakly to the blue in most objects, perhaps due to scattering and absorption by dust particles. We find that a polarization increase in the BAL troughs is a general property of polarized BAL QSOs, indicating an excess of scattered light relative to direct light, and consistent with the unification of BAL QSOs and non-BAL QSOs. We have also discovered evidence of resonantly scattered photons in the red wing of the C IV broad emission lines of a few objects. In most cases, the broad emission lines have lower polarization and a different position angle than the continuum. The polarization characteristics of low-ionization BAL QSOs are similar to those of high-ionization BAL QSOs, suggesting a similar BAL wind geometry.Comment: 39 pages, 6 figures (20 .gif files), accepted for publication in The Astrophysical Journal Supplement

Effects of Chlamydia trachomatis Infection on Fertility; A Case-Control Study.

BACKGROUND: Nowadays, Chlamydia trachomatis is known as a causative agent of infertility. Because of, asymptomatic nature of infection, many may suffer from its lasting complications such as infertility. This study was performed in Tehran during April 2007 to April 2008 to compare the prevalence of Chlamydia trachomatis infection in fertile and infertile women using ELISA and PCR methods. METHODS: Overall, 234 infertile and 223 pregnant women, as the fertile group, participated in this hospital-based case-control study. After completing an informed consent form and the questionnaire, first catch urine and blood sample were obtained for PCR and ELISA (IgG, IgM) tests, respectively. Logistic regression analysis was used to control possible confounding factors, and determine adjusted odds ratio of infertility due to the infection. RESULTS: PCR results revealed that 29 (12.4%) of the infertile and 19 (8.5%) of the fertile women were positive for C. trachomatis infection (p = 0.440). IgG was positive in 21 (9.0%) of the infertile and 11 (5.0%) in the fertile group (p = 0.093). IgM assays identified that 2 (0.9%) of the infertile and 4 (1.8%) of the fertile women were positive for the micro-organism (p = 0.375). CONCLUSION: We found no significant differences among fertile and infertile women for Chlamydia trachomatis infection. Nevertheless, molecular techniques which are more sensitive, more specific and non-invasive can be used to detect C. trachomatis infection

Absolute emission altitude of pulsars: PSRs B1839+09, B1916+14 and B2111+46

We study the mean profiles of the multi--component pulsars PSRs B1839+09, B1916+14 and B2111+46. We estimate the emission height of the core components, and hence find the absolute emission altitudes corresponding to the conal components. By fitting Gaussians to the emission components, we determine the phase location of the component peaks. Our findings indicate that the emission beams of these pulsars have the nested core--cone structures. Based on the phase location of the component peaks, we estimate the aberration--retardation (A/R) phase shifts in the profiles. Due to the A/R phase shift, the peak of the core component in the intensity profile and the inflection point of the polarization angle swing are found to be symmetrically shifted in the opposite directions with respect to the meridional plane in such a way that the core shifts towards the leading side and the polarization angle inflection point towards the trailing side. We have been able to locate the phase location of the meridional plane and to estimate the absolute emission altitude of both the core and the conal components relative to the neutron star centre, using the exact expression for the A/R phase shift given by Gangadhara (2005).Comment: 10 pages, 6 figures, Accepted for Publication in A&

Exploring efficient photocatalytic degradation of humic acid from aqueous solution with plant-based ZnFe₂O₄@TiO₂ magnetic nanocomposite using Elaeagnus angustifolia tree bark methanolic extract

In the process of sanitizing drinking water, humic acid present in drinking water sources reacts with chlorine disinfectant and forms mutagenic defective, and carcinogenic disinfection byproducts such as trihalomethanes and haloacetic acids. In the present study, the methanolic extract of Elaeagnus angustifolia tree bark was used for the synthesis of ZnFe₂O₄@TiO₂ nanocomposite and then properties and structural elements and diagnostic features of nanoparticles were analyzed. According to the results, the ZnFe₂O₄@TiO₂ nanocomposites have an average crystalline size of ∼65-250 nm. Also, the effects of pH (3-11), nanoparticle dose (0.005-0.1 g/L), and humic acid concentration (2-15 mg/L) were examined up to 120 min of time. From the results, the highest removal percentages achieved about 100% at optimal conditions (pH = 3, nanocomposite dose= 0.05 g/L and humic acid initial concentration = 2 mg/L). The results of this research showed that the efficiency of nanocomposite at the highest concentration of humic acid that was investigated in this research (15 mg/L) was about 95.67%. Therefore, it can be concluded that this nanocomposite, while being cost-effective and environmentally friendly, is also very effective in removing humic acid from an aqueous solution

Sustainable green synthesis of ZnFe₂O₄@ZnO nanocomposite using Oleaster tree bark methanolic extract for photocatalytic degradation of aqueous humic acid in the presence of UVc irradiation

One of the most important humic substances in water is humic acid. These substances enter water sources through soils, sediments of aquatic animals, plants and sewage. Therefore, removing them from water sources is very important. In this study, the photocatalytic removal of humic acid was investigated using zinc ferrite nanoparticles loaded with zinc oxide (ZnFe₂O₄@ZnO). This research was conducted in an experimental-interventional way in a batch reactor on a laboratory scale. A novel and facile method was applied for catalyst synthesis in different conditions, and it was structurally and morphologically characterized by XRD, FT-IR, SEM, DLS and EDS mapping techniques. The effects of pH (3–11), nanoparticle dose (0.005–0.1 g/L), and humic acid concentration (2–15 mg/L) were examined up to 120 min of time. The results showed that the efficiency of humic acid degradation by ZnFe₂O₄@ZnO reached 95% in optimal conditions. Also, it was found that this nanocomposite has an acceptable reusability and recovery after being tested in five stages

Solidification enhancement in a multi-tube latent heat storage system for efficient and economical production: Effect of number, position and temperature of the tubes

Copyright: © 2021 by the authors. Thermal energy storage is an important component in energy units to decrease the gap between energy supply and demand. Free convection and the locations of the tubes carrying the heat-transfer fluid (HTF) have a significant influence on both the energy discharging potential and the buoyancy effect during the solidification mode. In the present study, the impact of the tube position was examined during the discharging process. Liquid-fraction evolution and energy removal rate with thermo-fluid contour profiles were used to examine the performance of the unit. Heat exchanger tubes are proposed with different numbers and positions in the unit for various cases including uniform and non-uniform tubes distribution. The results show that moving the HTF tubes to medium positions along the vertical direction is relatively better for enhancing the solidification of PCM with multiple HTF tubes. Repositioning of the HTF tubes on the left side of the unit can slightly improve the heat removal rate by about 0.2 in the case of p5-u-1 and decreases by 1.6% in the case of p5-u-2. It was found also that increasing the distance between the tubes in the vertical direction has a detrimental effect on the PCM solidification mode. Replacing the HTF tubes on the left side of the unit negatively reduces the heat removal rate by about 1.2 and 4.4%, respectively. Further, decreasing the HTF temperature from 15◦C to 10 and 5◦C can increase the heat removal rate by around 7 and 16%, respectively. This paper indicates that the specific concern to the HTF tube arrangement should be made to improve the discharging process attending free convection impact in phase change heat storage