Rarefied flow past a flat plate at incidence

Results of a numerical study using the direct simulation Monte Carlo (DSMC) method are presented for the transitional flow about a flat plate at 40 deg incidence. The plate has zero thickness and a length of 1.0 m. The flow conditions simulated are those experienced by the Shuttle Orbiter during reentry at 7.5 km/s. The range of freestream conditions are such that the freestream Knudsen number values are between 0.02 and 8.4, i.e., conditions that encompass most of the transitional flow regime. The DSMC simulations show that transitional effects are evident when compared with free molecule results for all cases considered. The calculated results demonstrate clearly the necessity of having a means of identifying the effects of transitional flow when making aerodynamic flight measurements as are currently being made with the Space Shuttle Orbiter vehicles. Previous flight data analyses have relied exclusively on adjustments in the gas-surface interaction models without accounting for the transitional effect which can be comparable in magnitude. The present calculations show that the transitional effect at 175 km would increase the Space Shuttle Orbiter lift-drag ratio by 90 percent over the free molecule value

Giant Fluctuations of Coulomb Drag in a Bilayer System

We have observed reproducible fluctuations of the Coulomb drag, both as a function of magnetic field and electron concentration, which are a manifestation of quantum interference of electrons in the layers. At low temperatures the fluctuations exceed the average drag, giving rise to random changes of the sign of the drag. The fluctuations are found to be much larger than previously expected, and we propose a model which explains their enhancement by considering fluctuations of local electron properties.Comment: 10 pages, 4 figure

How the nursing associate role is viewed by different stakeholders: a qualitative research study

Background: The nursing associate role was created following a review by Health Education England in 2015 that examined nurse education and training so that capacity and improvements could be made to the provision of care in England. Objective: To explore different stakeholder perspectives of how the nursing associate role has been embedded within local healthcare practice. Design: The study was designed to explore and evaluate the role of the nursing associate in practice from the perspectives of those stakeholders who have experience of working with the nursing associate. Setting(s): Online semi-structured interviews. Participants: 9 stakeholder participants who had direct contact with the nursing associate or trainee nursing associate in the practice setting. Methods: A mixed-methods qualitative approach was used, which included a creative methodological approach in the form of photo-elicitation and semi-structured interviews to explore the lived experience of participants. Results: Analysis revealed 2 superordinate themes: (1) the contribution of the nursing associate; (2) real-work perspectives of the role. Conclusions: The findings demonstrated that the role was important to the provision of care, but that there were challenges related to communication, support and education provision throughout the organisations

Does mating negatively affect female immune defences in insects?

This is the final version. Available from Brill Academic Publishers via the DOI in this record.Immunity is an important mechanism of protection against pathogens and parasites. One factor that can influence immunity is mating. During mating, male-derived materials are transferred to females, and the physical contact also involves the potential risk of sexually transmitted infections, and wounding. Thus, mating can challenge a female’s immune system. This review focuses on exploring how immunity and mating interact in female insects. Although mating has been shown to cause female immune responses in several species, the responses do not always match the observed resistance to pathogens/parasites. Mating up-regulates female immune responses while female resistance is reduced compared to virgin females in some species, and vice versa in other taxa. We discuss why mismatches occur and why post-mating female resistance differs among species, and suggest that measured immune responses may not correlate with female resistance. Also, the mating system will play a major role. Polyandrous mating systems can generate intense post-mating sexual conflict, which can impose high costs of mating on females. Reduced female post-mating resistance may be due to direct suppression of female immunity by males. Alternatively, polyandry may increase the risk of sexually transmitted infections. If this is the major factor driving female post-mating resistance, females of polyandrous species should have higher post-mating immunity. To date, there are insufficient numbers of studies to fully answer the question ‘does mating negatively affect female immune defences in insects?’ To elucidate the links between immunity and mating in females, we need more studies in more species with varied mating systems.European CommissionMarie Skłodowska-Curi

The Initial Mass Function of Low-Mass Stars and Brown Dwarfs in Taurus

By combining deep optical imaging and infrared spectroscopy with data from the Two-Micron All-Sky Survey (2MASS) and from previous studies (e.g., Briceno et al.), I have measured the Initial Mass Function (IMF) for a reddening-limited sample in four fields in the Taurus star forming region. This IMF is representative of the young populations within these fields for masses above 0.02 Msun. Relative to the similarly derived IMF for the Trapezium Cluster (Luhman et al.), the IMF for Taurus exhibits a modest deficit of stars above one solar mass (i.e., steeper slope), the same turnover mass (~0.8 Msun), and a significant deficit of brown dwarfs. If the IMF in Taurus were the same as that in the Trapezium, 12.8+/-1.8 brown dwarfs (>0.02 Msun) are expected in these Taurus fields where only one brown dwarf candidate is found. These results are used to test theories of the IMF.Comment: to be published in The Astrophysical Journal, 24 pages, 6 figures, also found at http://cfa-www.harvard.edu/~kluhman/taurus

A shallow water ferrous-hulled shipwreck reveals a distinct microbial community.

This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY).Shipwrecks act as artificial reefs and provide a solid surface in aquatic systems for many different forms of life to attach to, especially microbial communities, making them a hotspot of biogeochemical cycling. Depending on the microbial community and surrounding environment, they may either contribute to the wreck’s preservation or deterioration. Even within a single wreck, preservation and deterioration processes may vary, suggesting that the microbial community may also vary. This study aimed to identify the differences through widespread sampling of the microbial communities associated with the Pappy Lane shipwreck (NC shipwreck site #PAS0001), a shallow water ferrous-hulled shipwreck in Pamlico Sound, North Carolina to determine if there are differences across the wreck as well as from its surrounding environment. Loose shipwreck debris, drilled shipcores, surrounding sediment, and seawater samples were collected from the Pappy Lane shipwreck to characterize the microbial communities on and around the shipwreck. Results indicated that the shipwreck samples were more similar to each other than the surrounding sediment and aquatic environments suggesting they have made a specialized niche associated with the shipwreck. There were differences between the microbial community across the shipwreck, including between visibly corroded and non-corroded shipwreck debris pieces. Relative abundance estimates for neutrophilic iron-oxidizing bacteria (FeOB), an organism that may contribute to deterioration through biocorrosion, revealed they are present across the shipwreck and at highest abundance on the samples containing visible corrosion products. Zetaproteobacteria, a known class of marine iron-oxidizers, were also found in higher abundance on shipwreck samples with visible corrosion. A novel Zetaproteobacteria strain, Mariprofundus ferrooxydans O1, was isolated from one of the shipwreck pieces and its genome analyzed to elucidate the functional potential of the organism. In addition to iron oxidation pathways, the isolate has the genomic potential to perform carbon fixation in both high and low oxygen environments, as well as perform nitrogen fixation, contributing to the overall biogeochemical cycling of nutrients and metals in the shipwreck ecosystem. By understanding the microbial communities associated with shallow water ferrous-hulled shipwrecks, better management strategies and preservation plans can be put into place to preserve these artificial reefs and non-renewable cultural resources.ECU Open Access Publishing Support Fun

Beyond the multidisciplinary in fan studies: Learning how to talk among disciplines

In light of the Fan Studies Network's statement regarding fan studies being overrun with whiteness, we are in a unique position to engage in scholarship that challenges the overwhelmingly white and Global North–centric structures that define how we study fan cultures. Multidisciplinarity, which may be understood as disciplines laid side by side, should be contrasted with interdisciplinarity, which requires true dialogue. Despite recent field-shifting work by fan studies scholars such as Bertha Chin, Lori Morimoto, Rukmini Pande, and Rebecca Wanzo, more work needs to be done to both acknowledge and build on current research in transcultural fandom. In a dialogue that reflects the progress of our own striving toward interdisciplinary and transcultural work in fan studies, we seek to demonstrate a possible way forward for the field of fan studies to become more truly interdisciplinary and transcultural in its focus

Magnetic structure of EuFe2As2 determined by single crystal neutron diffraction

Among various parent compounds of iron pnictide superconductors, EuFe2As2 stands out due to the presence of both spin density wave of Fe and antiferromagnetic ordering (AFM) of the localized Eu2+ moment. Single crystal neutron diffraction studies have been carried out to determine the magnetic structure of this compound and to investigate the coupling of two magnetic sublattices. Long range AFM ordering of Fe and Eu spins was observed below 190 K and 19 K, respectively. The ordering of Fe2+ moments is associated with the wave vector k = (1,0,1) and it takes place at the same temperature as the tetragonal to orthorhombic structural phase transition, which indicates the strong coupling between structural and magnetic components. The ordering of Eu moment is associated with the wave vector k = (0,0,1). While both Fe and Eu spins are aligned along the long a axis as experimentally determined, our studies suggest a weak coupling between the Fe and Eu magnetism.Comment: 7 pages, 7 figure

Field induced spin reorientation and giant spin-lattice coupling in EuFe2As2

We have studied a EuFe2As2 single crystal by neutron diffraction under magnetic fields up to 3.5 T and temperatures down to 2 K. A field induced spin reorientation is observed in the presence of a magnetic field along both the a and c axes, respectively. Above critical field, the ground state antiferromagnetic configuration of Eu$^{2+}$ moments transforms into a ferromagnetic structure with moments along the applied field direction. The magnetic phase diagram for Eu magnetic sublattice in EuFe2As2 is presented. A considerable strain ($\sim$0.9%) is induced by the magnetic field, caused by the realignment of the twinning structure. Furthermore, the realignment of the twinning structure is found to be reversible with the rebound of magnetic field, which suggested the existence of magnetic shape-memory effect. The Eu moment ordering exhibits close relationship with the twinning structure. We argue that the Zeeman energy in combined with magnetic anisotropy energy is responsible for the observed spin-lattice coupling.Comment: 5 pages, 4 figure