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

Effect of gold nanoparticles on prostate dose distribution under Ir-192 internal and 18 MV external radiotherapy procedures using gel dosimetry and monte carlo method

Background: Gel polymers are considered as new dosimeters for determining radiotherapy dose distribution in three dimensions. Objective: The ability of a new formulation of MAGIC-f polymer gel was assessed by experimental measurement and Monte Carlo (MC) method for studying the effect of gold nanoparticles (GNPs) in prostate dose distributions under the internal Ir-192 and external 18MV radiotherapy practices. Method: A Plexiglas phantom was made representing human pelvis. The GNP shaving 15 nm in diameter and 0.1 mM concentration were synthesized using chemical reduction method. Then, a new formulation of MAGIC-f gel was synthesized. The fabricated gel was poured in the tubes located at the prostate (with and without the GNPs) and bladder locations of the phantom. The phantom was irradiated to an Ir-192 source and 18 MV beam of a Varian linac separately based on common radiotherapy procedures used for prostate cancer. After 24 hours, the irradiated gels were read using a Siemens 1.5 Tesla MRI scanner. The absolute doses at the reference points and isodose curves resulted from the experimental measurement of the gels and MC simulations following the internal and external radiotherapy practices were compared. Results: The mean absorbed doses measured with the gel in the presence of the GNPs in prostate were 15 and 8 higher than the corresponding values without the GNPs under the internal and external radiation therapies, respectively. MC simulations also indicated a dose increase of 14 and 7 due to presence of the GNPs, for the same experimental internal and external radiotherapy practices, respectively. Conclusion: There was a good agreement between the dose enhancement factors (DEFs) estimated with MC simulations and experiment gel measurements due to the GNPs. The results indicated that the polymer gel dosimetry method as developed and used in this study, can be recommended as a reliable method for investigating the DEF of GNPs in internal and external radiotherapy practices. © 2015 Shiraz University of Medical Sciences. All Rights Reserved

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

Benefits of greenhouse gas mitigation on the supply, management, and use of water resources in the United States

Climate change impacts on water resources in the United States are likely to be far-reaching and substantial because the water is integral to climate, and the water sector spans many parts of the economy. This paper estimates impacts and damages from five water resource-related models addressing runoff, drought risk, economics of water supply/demand, water stress, and flooding damages. The models differ in the water system assessed, spatial scale, and unit of assessment, but together provide a quantitative and descriptive richness in characterizing water sector effects that no single model can capture. The results, driven by a consistent set of greenhouse gas (GHG) emission and climate scenarios, examine uncertainty from emissions, climate sensitivity, and climate model selection. While calculating the net impact of climate change on the water sector as a whole may be impractical, broad conclusions can be drawn regarding patterns of change and benefits of GHG mitigation. Four key findings emerge: 1) GHG mitigation substantially reduces hydro-climatic impacts on the water sector; 2) GHG mitigation provides substantial national economic benefits in water resources related sectors; 3) the models show a strong signal of wetting for the Eastern US and a strong signal of drying in the Southwest; and 4) unmanaged hydrologic systems impacts show strong correlation with the change in magnitude and direction of precipitation and temperature from climate models, but managed water resource systems and regional economic systems show lower correlation with changes in climate variables due to non-linearities created by water infrastructure and the socio-economic changes in non-climate driven water demand

Target dose enhancement factor alterations related to interaction between the photon beam energy and gold nanoparticles� size in external radiotherapy: Using Monte Carlo method

Introduction: To study the effects of various sizes of gold nanoparticles (GNPs) on the target tissue dose enhancement factor at the time of external radiotherapy with various photon beam energies ranged from kilovolts (kVs) to Megavolts (MVs) by using Monte Carlo (MC) method. Materials and Methods: MCNPX code was used for simulating the interaction of photon beams with various levels of energy with water solution including various sizes of GNPs at a presumptive region including a tumor. Initially, a water phantom including GNPs, which consisted a tumor with a size of 1�1�1 cm3 was simulated. The phantom was irradiated with various external monoenergetic photon beam ranged from kVs to MVs. The macroscopic dose enhancement factor (DEF) of the tumor due to the presence of various sizes of GNPs (15, 50, and 100 nm) at a concentration of 7 mg/g was calculated. Results: The tumor (target) DEF at the presence of the GNPs was obtained within the range of 1.69 to 2.66 kV and 1.08 to 1.10 MV photon beam. The highest DEF was found at 50 kV photon beam. The target DEF was increased with the increase in GNPs size. Conclusion: The calculated target DEFs at the presence of GNPs for photon beam energies in kV were similar to the previous studies. For the photon beam energies in MV, after a decrease at the interface of two regions of pure water and solution including the GNPs, DEF the tumor was increased and with 2 and 6 MV energies reached to its maximum at the depths 6.2 and 6.5 cm, respectively. © 2015, Semnan University of Medical Sciences. All rights reserved

Long-term Hydro-economic Analysis Tool for Evaluating Global Groundwater Cost and Supply: Superwell v1.0

Groundwater plays a key role in meeting water demands, supplying over 40 % of irrigation water globally, with this role likely to grow as water demands and surface water variability increase. A better understanding of the future role of groundwater in meeting sectoral demands requires an integrated hydro-economic evaluation of its cost and availability. Yet substantial gaps remain in our knowledge and modeling capabilities related to groundwater availability, feasible locations for extraction, extractable volumes, and associated extraction costs, which are essential for large-scale analyses of integrated human-water systems scenarios, particularly at the global scale. To address these needs, we developed Superwell, a physics-based groundwater extraction and cost accounting model that operates at 0.5° (≈50x50 km) gridded spatial resolution with global coverage. The model produces location-specific groundwater supply-cost curves that provide the levelized cost to access different quantities of available groundwater. The inputs to Superwell include recent high-resolution hydrogeologic datasets of permeability, porosity, aquifer thickness, depth to water table, and hydrogeological complexity zones. It also accounts for well capital and maintenance costs, and the energy costs required to lift water to the surface. The model employs a Theis-based scheme coupled with an amortization-based cost accounting formulation to simulate groundwater extraction and quantify the cost of groundwater pumping. The result is a spatiotemporally flexible, physically-realistic, economics-based model that produces groundwater supply-cost curves. We show examples of these supply-cost curves and the insights that can be derived from them across a set of scenarios designed to explore model outcomes. The supply-cost curves produced by the model show that most nonrenewable groundwater in storage globally is extractable at costs lower than 0.23 USD/m3, while half of the volume remains extractable at under 0.138 USD/m3. We also demonstrate and discuss examples of how these cost curves could be used by linking Superwell’s outputs with other models to explore coupled human-environmental systems challenges, such as water resources planning and management, or broader analyses of multi-sectoral feedbacks

Educational difference in the prevalence of osteoporosis in postmenopausal women: a study in northern Iran

<p>Abstract</p> <p>Background</p> <p>Osteoporosis is the most common metabolic bone disease in the world and it is rapidly increasing in Iran. In this study the relationship between educational levels and osteoporosis was investigated among Iranian postmenopausal women.</p> <p>Method and subjects</p> <p>Seven hundred and six women aged 50-75 years old were randomly recruited from urban (<it>n </it>= 440) and rural (<it>n </it>= 266) areas in Guilan. Osteoporosis was diagnosed by quantitative ultrasound technique and dual X-ray absorptiometry. Serum 25(OH) D3, body weight and height were measured in all subjects. Other data including age, educational level, menopause age, medications and history of illness were also collected.</p> <p>Results</p> <p>We found that the prevalence of osteoporosis was significantly greater among women with low educational level than women with high educational status (18.0% vs 3.8% <it>P </it>< 0.0001). However, women with low educational level had higher mean serum level of vitamin D than women with high educational level. Osteoporosis was significantly more prevalent among women living in rural areas than women living in urban areas (19.1% v.s 13.3%, <it>P </it>< 0.0001).</p> <p>Conclusion</p> <p>This study showed that educational level is associated with bone health in this population of postmenopausal women with significantly higher osteoporosis found in lower social groups. Therefore, we suggest that women with low social level should be carefully evaluated for signs of osteoporosis during routine physical examinations.</p