1,211 research outputs found
A New Physical Picture of Pairing Mechanism in Superconductors: Could the Electron be a Composite Particle?
The physical pictures of the electron pairing structure and pairing
mechanisms in superconductors are reviewed. An initial idea for a new physical
picture of the origin and nature of the pairing is proposed. The idea is based
on the assumption that the electron is no longer a single fundamental but a
composite particle. This property is hidden in the normal state. How a natural
pairing could occur in the superconducting state and the processes closely
related to this change inside the atom are developed in a new physical picture
with new insight(although it needs verification and real evidence for now). An
attempt, to show that a zero resistance to a direct current and Josephson
effects could be used as example evidences for this assumption, is presented by
means of this new insight in general schematical analogy. A possible new
research direction, hopefully to achieve room temperature superconductors, is
suggested as a consequence.Comment: 17 pages, 12 figures, 46 Reference
Vulnerability Reduction of Technology-Based Business research in the Last four Decades: A Bibliometric Analysis
Natural and man-made disasters have increased the attention of practitioners and researchers to vulnerability. Identifying business vulnerability is one of the basic elements of strategic analysis and public policy. The purpose of this paper is to explore evolutionary pathways to reduce the vulnerability of technology-based businesses. The intellectual structure of this subject was examined using both bibliometric co-occurrence and co-citation analyses. We focused on 629 articles published between 1981 and 2021. This article identifies four specific areas. Business performance, small business vulnerability, sources of sustainability in business, and adaptation policy assessment. A novel framework was developed based on the most prominent papers identified in co-citation, and the highly cited papers. The proposed model includes drivers, vulnerability appearance, and vulnerability reduction. This study examines the basis of research concepts, themes, and communities in reducing the vulnerability of technology-based businesses. This article identifies business vulnerability as one of the relevant areas to disaster economics and sustainability studies
Compact superconducting dual-log spiral resonator with high Q-factor and low power dependence
A new dual-log spiral geometry is proposed for microstrip resonators, offering substantial advantages in performance and size reduction at subgigahertz frequencies when realized in superconducting materials. The spiral is logarithmic in line spacing and width such that the width of the spiral line increases smoothly with the increase of the current density, reaching its maximum where the current density is maximum (in its center for 2 resonators). Preliminary results of such a logarithmic ten-turn (2 5 turns) spiral, realized with double-sided YBCO thin film, showed a -factor seven times higher than that of a single ten-turn uniform spiral made of YBCO thin film and 64 times higher than a copper counterpart. The insertion loss of the YBCO dual log-spiral has a high degree of independence of the input power in comparison with a uniform Archimedian spiral, increasing by only 2.5% for a 30-dBm increase of the input power, compared with nearly 31% for the uniform spiral. A simple approximate method, developed for prediction of the resonant frequency of the new resonators, shows a good agreement with the test results
A Dog with Multiple Infections of Enteric Parasitic Zoonosis in Mashhad City, North-East of Iran; a Case Report
Aims: In this study, we examined stool specimen from a 3-year-old domesticated dog, which was referred to a veterinary clinic with clinical signs such as nausea or vomiting, dysentery, cachexia and rash in Mashhad city, northeast of Iran. Patient & Methods: A 3-year-old pet dog was referred to veterinary clinic of Mashhad in February 2016 by symptoms including, nausea or vomiting, dysentery, cachexia and rash in Mashhad City, Northeast of Iran. For parasitological examination, formalin-ether concentration technique was used. Fecal smears were made from the sediment, stained with iodine and observed by light microscope. Modified Ziehl Neelsen method was used for the detection of Cryptosporidium spp. Findings: The animal was infected with 10 disease-causing parasites; Taenia spp., Fasciola spp., Dicrocoelium dendriticum, Acanthocephal spp., Trichuris vulpis, Hook worm, Giardia spp., Blastocystis spp., Eimeria spp., and Cystoisospora spp. Conclusion: Domestic and stray dog could be an important sources for distribution of zoonoses disease especially parasitic agents
Role of the BANYULS(BAN) Gene from Arabidopsis Thaliana in Transgenic Alfalfa Expression of Anthocyanins and Proanthocyanidins
Condensed tannins (CTs) are flavonoid oligomers, many of which have beneficial effects on animal (bloat safe) and human health. The BAN gene encodes anthocyanidin reductase (ANR), an enzyme proposed to convert anthocyanidins to their corresponding 2,3-cis-flavan-3-ols (Xie et al., 2003). Ectopic expression of BAN in Alfalfa transgenic foliage results in accumulation of CTs. Thus, it has been assumed that the BAN gene also acts in starter units for the condensation of tannins in Alfalfa
Investigating the effects of heavy metals in the waste leachate on the groundwater quality near the landfill (case study: Landfill of Saravan, Rasht)
The main and fundamental scientific reason of scientific community attention to the issue of leachate pollution and its treatment is the possible danger of contamination of water, soil and to some extent air. The reason is that the leachate of landfill in fact is acomplex waste withhigh pollution. Today, in our country, especially in northern areas due to high groundwater levels, the problem of waste disposal and the effects of their leachate entering alluvial groundwater and aquifer contamination downstream based on hydrodynamic thickness in the movement of water is highly regarded andentering a considerable amount of pollution (nitrates, heavy metals, etc.) to underground water sources used for drinking and agriculture, in the long term become a social problem. Saravan landfill is located on 15 km road Rasht of to Tehran is like a black spot in the in the green Hyrcanian forest and receives more than 500 tons of waste daily from provinces cities,particularly Rasht which with no environmental assessment for selected waste disposal, waste disposal is inadequate in Saravan and because of evaporation, fermentation and decomposition of the waste and leachate percolation into the soil and water resources it is associated with high pollution and unleashed leachate river in the heart of nature and based on the ranking of Index criteria it is unacceptable. In this study, sampling was conducted in 2 upstream wells, 3 downstream wells of Saravan landfill then the samples were analyzed by atomic absorption. The results indicate the presence of heavy metals (chromium - lead – zinc -iron - manganese) in water of downstream wells of the landfill compared to upstream wells and the control wells or in other words, it was significantly more than the control and upstream wells and the average concentrations of Pb, Cr, MN, Fe higher than drinking water standards and the mean concentration of MN and Cr in the research water wells was more than standard water for irrigation and agricultural. It shows the leachate percolation into soil and ground water that has been polluted the nearby water of the landfill.Keywords: Groundwater, Landfill, Leachate, Heavy Metals, Sarava
Investigating the challenges of biodiversity management of Sefidkuh Khoramabad protected area by using the Delphi method
The main source of economic and agricultural development of all countries is natural resources. The dependency of local communities on natural resources and protected areas, and the excessive exploitation of forests and pastures and wildlife, has led to the destruction and degradation of biodiversity. The basis of managing protected areas in Iran is based on protection, research, training and entertaining, but in reality, protection is only limited to one fifth of these areas, which are safe. There is no management on the surrounding lands (the danger of islandization). Therefore, the purpose of this study is to identify and investigate the challenges of biodiversity management of Sefidkuh Khoramabad Protected Area by using Delphi method. This is a descriptive-analytic study. Thus, after identifying the available biodiversity and field visits and identifying the threats in the region, questionnaires were designed by experts regarding the Likert scale and were given to experts and specialists.The questions were answered by the experts and were analyzed by SPSS Software, the answers were prioritized by regression and descriptive analysis of existing threats and explained its relationship with four research variables (academic degree, familiarity with the region, job and employee of the organization). Then, this priority was organized as a questionnaire, and was given to the expert for final approval and identification of the main threats. Finally, some suggestions and recommendations are given.Keywords: Biodiversity, Challenges, Protected Areas, Sefidkouh, Prioritizatio
Laboratory Evaluation of Five Chitin Synthesis Inhibitors Against the Colorado Potato Beetle, Leptinotarsa decemlineata
Results of laboratory experiments are reported that tested the effects of five chitin synthesis inhibitors, diflubenzuron, cyromazine, lufenuron, hexaflumuron and triflumuron. on second instars of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Crysomelidae), originally collected from potato fields of Bostanabaad, a town 66 km southeast of Tabriz, Iran. In bioassays, the larvae were fed potato leaves dipped in aqueous solutions containing chitin synthesis inhibitors. The mortalities and abnormalities of the treated larvae were recorded 72 hours after treatments. LC50 values were 58.6, 69.6, 27.3, 0.79 and 81.4 mg ai/ L for diflubenzuron, cyromazine, lufenuron, hexaflumuron and triflumuron, respectively. Compared with phosalone, which is one of the common insecticides used for controlling this pest in Iran, lufenuron and hexaflumuron seem to be much more potent, and if they perform equally well in the field, they would be suitable candidates to be considered as reduced risk insecticides in management programs for L. decemlineata due to much wider margin of safety for mammals and considerably fewer undesirable environmental side effects
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