Magnetic levitation force between a superconducting bulk magnet and a permanent magnet

The current density in a disk-shaped superconducting bulk magnet and the magnetic levitation force exerted on the superconducting bulk magnet by a cylindrical permanent magnet are calculated from first principles. The effect of the superconducting parameters of the superconducting bulk is taken into account by assuming the voltage-current law and the material law. The magnetic levitation force is dominated by the remnant current density, which is induced by switching off the applied magnetizing field. High critical current density and flux creep exponent may increase the magnetic levitation force. Large volume and high aspect ratio of the superconducting bulk can enhance the magnetic levitation force further.Comment: 18 pages and 8 figure

Anomalous magnetic response of the spin-one-half Falicov-Kimball model

The infinite-dimensional spin one-half Falicov-Kimball model in an external magnetic field is solved exactly. We calculate the magnetic susceptibility in zero field, and the magnetization as a function of the field strength. The model shows an anomalous magnetic response from thermally excited local moments that disappear as the temperature is lowered. We describe possible real materials that may exhibit this kind of anomalous behavior.Comment: 17 pages, 6 encapsulated postscript figures (included), submitted to Phys. Rev.

A comparison study of geostatistical simulation for predicting soil texture

Non-Peer Reviewe

DNS study of a pipe flow following a step increase in flow rate

Direct numerical simulation (DNS) is conducted to study the transient flow in a pipe following a near-step increase of flow rate from an initial turbulent flow. The results are compared with those of the transient flow in a channel reported in He and Seddighi (2013). It is shown that the flow again exhibits a laminar–turbulent transition, similar to that in a channel. The behaviours of the flow in a pipe and a channel are the same in the near-wall region, but there are significant differences in the centre of the flow. The correlation between the critical Reynolds number and free stream turbulence previously established for a channel flow has been shown to be applicable to the pipe flow. The responses of turbulent viscosity, vorticity Reynolds number, and budget terms are analysed. Some significant differences have been found to exist between the developments of the vorticity Reynolds number in the pipe and channel flows

Alcohol consumption, cigarette smoking and the risk of subtypes of head-neck cancer: results from the Netherlands Cohort Study

Background: Prospective data on alcohol consumption, cigarette smoking and risk of head-neck cancer (HNC) subtypes, i.e. oral cavity cancer (OCC), oro-/hypopharyngeal cancer (OHPC), and laryngeal cancer (LC), are limited. We investigated these associations within the second largest prospective study on this topic so far, the Netherlands Cohort Study. Methods: 120,852 participants completed a questionnaire on diet and other cancer risk factors in 1986. After 17.3 years of follow-up, 395 HNC (110 OCC, 83 OHPC, and 199 LC) cases and 4288 subcohort members were available for case-cohort analysis using Cox proportional hazards models. Results: For total HNC, the multivariable adjusted incidence rate ratio (RR) was 2.74 (95% confidence interval (CI) 1.85-4.06) for those drinking >= 30 g ethanol/day compared with abstainers; in subtypes, RRs were 6.39 for OCC, 3.52 for OHPC, and 1.54 for LC. Compared with never cigarette smokers, current cigarette smokers had a RR of 4.49 (95% CI 3.11-6.48) for HNC overall, and 2.11 for OCC, 8.53 for OHPC, and 8.07 for LC. A significant, positive, multiplicative interaction between categories of alcohol consumption and cigarette smoking was found for HNC overall (P interaction 0.03). Conclusions: Alcohol consumption and cigarette smoking were independently associated with risk of HNC overall, with a positive, multiplicative interaction. The strength of these associations differed among HNC-subtypes: OCC was most strongly associated with alcohol consumption but most weakly with cigarette smoking, whereas LC was not statistically significantly associated with alcohol consumption

Using meta-research methods to examine the inclusion of women, pregnant women, and women-specific health outcomes in studies that contributed to the dietary reference intakes for one-carbon metabolism micronutrients

Purpose: Maternal micronutrient deficiencies occurring during periconceptional, pregnancy, and postpartum periods are a leading cause of adverse pregnancy outcomes globally. The Dietary Reference Intakes (DRIs) are a set of reference values used to assess and guide nutrient intakes of healthy individuals. However, the current DRIs for pregnancy and lactation may be limited in their methods and included populations. The present study analyzed the current DRIs for their inclusion of pregnant women and geographic representativeness. Methods: Meta-research methods were applied to the DRI report for vitamins B6, B12, folate, and choline in four steps: search, screening, full-text data extraction, and data analysis. For each target micronutrient, sections that contributed data to setting the average requirement were focused on, “Selection of Indicators for Estimating the Requirement,” “Findings by Life Stage and Gender Group,” and “Tolerable Upper Intake Limit” for adults, pregnancy, and lactation sub-sections. Screening involved reviewing the reference list to determine whether a reference directly contributed to setting the DRI. Full-text data extraction of primary data was conducted in areas of: 1) administrative information; 2) study methods; 3) human population characteristics; and 4) non-human subjects. Descriptive analyses were performed to describe the inclusion of women, pregnant women, geographic patterns, and demographic diversity. Results: For Vitamin B12, 100% of indicator studies and 71% of life stages studies included women, with a total of 3,246 women participants. However, none of the indicator studies and 15% of life stages studies included pregnant women, with a total of 556 pregnant women participants. None of the indicator studies and 8% of life stages studies reported health measurements specific to women, pregnancy, or lactation. Geographically, 54% of studies were conducted in the United States, and 18% took place in low-and middle-income countries. Data analysis is ongoing for the remaining micronutrients. Conclusions: Preliminary findings indicate that the body of evidence informing the current DRIs are limited in their inclusion of women and pregnant women. Numerous adverse pregnancy and birth outcomes are preventable through optimal maternal nutrition. Therefore, it is critical to ensure that the DRIs are suitable for their intended population. Despite their original intent for use in North America, the DRIs are widely adopted globally. Thus, geographic representation of the studies underlying the DRIs have implications for generalizability

Mechanical behaviour of additively manufactured lunar regolith simulant components

Additive manufacturing and its related techniques have frequently been put forward as a promising candidate for planetary in-situ manufacturing, from building life-sustaining habitats on the Moon to fabricating various replacements parts, aiming to support future extra-terrestrial human activity. This paper investigates the mechanical behaviour of lunar regolith simulant material components, which is a potential future space engineering material, manufactured by a laser-based powder bed fusion additive manufacturing system. The influence of laser energy input during processing was associated with the evolution of component porosity, measured via optical and scanning electron microscopy in combination with gas expansion pycnometry. The compressive strength performance and Vickers microhardness of the components were analysed and related back to the processing history and resultant microstructure of the lunar regolith simulant build material. Fabricated structures exhibited a relative porosity of 44 – 49% and densities ranging from 1.76 – 2.3 g cm-3 , with a maximum compressive strength of 4.2 ± 0.1 MPa and elastic modulus of 287.3 ± 6.6 MPa, the former is comparable to a typical masonry clay brick (3.5 MPa). The 2 AM parts also had an average hardness value of 657 ± 14 HV0.05/15, better than borosilicate glass (580 HV). This study has shed significant insight into realizing the potential of a laser-based powder bed fusion AM process to deliver functional engineering assets via in-situ and abundant material sources that can be potentially used for future engineering applications in aerospace and astronautics