Torque magnetometry study of the spin reorientation transition and temperature-dependent magnetocrystalline anisotropy in NdCo5

We present the results of torque magnetometry and magnetic susceptibility measurements to study in detail the spin reorientation transition (SRT) and magnetic anisotropy in the permanent magnet NdCo5. We further show simulations of the measurements using first-principles calculations based on density-functional theory and the disordered local moment picture of magnetism at finite temperatures. The good agreement between theory and experimental data leads to a detailed description of the physics underpinning the SRT. In particular we are able to resolve the magnetization of, and to reveal a canting between, the Nd and Co sublattices. The torque measurements carried out in the ac and ab planes near the easy direction allow us to estimate the anisotropy constants, K 1, K 2 and K 4 and their temperature dependences. Torque curves, τ(γ) recorded by varying the direction of a constant magnetic field in the crystallographic ac plane show a reversal in the polarity as the temperature is changed across the SRT (240 < T < 285 K). Within this domain, τ(γ) exhibits unusual features different to those observed above and below the transition. The single crystals of NdCo5 were grown using the optical floating zone technique

Tunability of the spin reorientation transitions with pressure in NdCo5

We present pressure-dependent magnetization measurements carried out in the domain of the spin reorientation transitions (SRTs) of a NdCo5 single crystal. The application of a hydrostatic pressure leads to a shift in the SRTs to higher temperatures. This shift is found to be very sensitive to pressure, with the SRT temperatures increasing at a rate of ≈17 K/GPa. To explain the experimental results, we have also performed first-principles calculations of the SRT temperatures for different applied strains, which corroborate the experimental findings. The calculations attribute the pressure dependence of the SRTs to a faster weakening of the Co contribution to the magnetocrystalline anisotropy with pressure compared to the Nd contribution

Measuring Organization of Large Surficial Clasts in Heterogeneous Gravel Beach Sediments

The natural stratification and interlocking “organization” of armored sediments in heterogeneous, coarse-grained, beaches provides protection and enhances habitat for borrowing sedentary megafauna and macrofauna such as hard-shelled clams. Here, we develop a novel metric for quantifying sediment organization of large surficial beach clasts through sedimentologic and photogrammetric analyses of 37 lower intertidal heterogeneous gravel beaches in western Prince William Sound, Alaska (USA). Grain size, photogrammetric, and Wolman Pebble Count clast-size data from 64, ~1-m2 study plots are combined into a clast-size-independent “Organization Metric” to quantify the degree of organization in the meshed arrangement of larger surficial sediments. This metric was validated through field manipulation experiments and comparisons of adjacent plots characterized by different clast sizes. Application of this metric to subsets of Prince William Sound beaches that underwent differential treatment following the Exxon Valdez oil spill reveals persistent physical effects of artificial beach disturbance even 21 years after the cleanup. This has important implications for beach management (e.g., cleaning or dredging) and for the diverse and productive sedentary megafaunal assemblages that live within these sediments. Overall, this study provides a new approach for quantifying organization of heterogenous coarse sediments in diverse natural settings; in particular, heterogenous gravel beaches

Understanding and characterizing the services sector in South Africa: An overview

The South African services sector is large and growing. This coupled with declining employment shares in manufacturing and mining (i.e. deindustrialization) suggests that South Africa is a de facto service-orientated economy. Employment patterns in services reveal a segmentation that is characterized by high-productivity, high-wage services, low-productivity, low-wage services, and government services. There has been sustained growth in services exports in the post-1994 period but the composition is biased toward traditional services. Increased entry into developing country markets is characterized by increasingly sophisticated services. A key driver of export growth is the expansion of foreign direct investment into developed country markets, and increasingly, into developing country markets, particularly African markets

Structural and magnetic properties of GdCo5−xNix

GdCo5 may be considered as two sublattices—one of Gd and one of Co—whose magnetizations are in antiparallel alignment, forming a ferrimagnet. Substitution of nickel in the cobalt sublattice of GdCo5 has been investigated to gain insight into how the magnetic properties of this prototype rare earth/transition-metal magnet are affected by changes in the transition-metal sublattice. Polycrystalline samples of GdCo5-xNix for 0 ≤ x ≤ 5 were synthesized by arc melting. Structural characterization was carried out by powder x-ray diffraction and optical and scanning electron microscope imagings of metallographic slides, the latter revealing a low concentration of Gd2(Co,Ni)7 lamellae for x ≤ 2.5. Compensation—i.e., the cancellation of the opposing Gd and transition-metal moments—is observed for 1< x < 3 at a temperature which increases with Ni content; for larger x , no compensation is observed below 360 K. A peak in the coercivity is seen at x ≈ 1 at 10 K coinciding with a minimum in the saturation magnetization. Density-functional theory calculations within the disordered local moment picture reproduce the dependence of the magnetization on Ni content and temperature. The calculations also show a peak in the magnetocrystalline anisotropy at similar Ni concentrations to the experimentally observed coercivity maximum

Enhancing the Teaching and Learning of Biometeorology in Higher Education

Information about the annual meeting organized by the organizations the International Society of Biometeorology (ISB) and the Students and New Professionals (SNP) held in Norfolk, Virginia from July 28 to August 1, 2016 is presented. The event was organized to improve the teaching methods of teachers and learning of students on high education biometeorology and the presentations, practical sessions and group discussions participated by attendees

Deprivation and chronic kidney disease – a review of the evidence

The relationship between socioeconomic deprivation and health is inequitable. Chronic kidney disease (CKD) is an archetypal disease of inequality, being more common amongst those living in deprivation. The prevalence of CKD is rising driven by an increase in lifestyle-related conditions. This narrative review describes deprivation and its association with adverse outcomes in adults with non-dialysis-dependent CKD including disease progression, end-stage kidney disease, cardiovascular disease and all-cause mortality. We explore the social determinants of health and individual lifestyle factors to address whether patients with CKD who are socioeconomically deprived have poorer outcomes than those of higher socioeconomic status. We describe whether observed differences in outcomes are associated with income, employment, educational attainment, health literacy, access to healthcare, housing, air pollution, cigarette smoking, alcohol use or aerobic exercise. The impact of socioeconomic deprivation in adults with non-dialysis-dependent CKD is complex, multi-faceted and frequently under-explored within the literature. There is evidence that patients with CKD who are socioeconomically deprived have faster disease progression, higher risk of cardiovascular disease and premature mortality. This appears to be the result of both socioeconomic and individual lifestyle factors. However, there is a paucity of studies and methodological limitations. Extrapolation of findings to different societies and healthcare systems is challenging, however, the disproportionate effect of deprivation in patients with CKD necessitates a call to action. Further empirical study is warranted to establish the true cost of deprivation in CKD to patients and societies

Producing polished prokaryotic pangenomes with the Panaroo pipeline

Population-level comparisons of prokaryotic genomes must take into account the substantial differences in gene content resulting from horizontal gene transfer, gene duplication and gene loss. However, the automated annotation of prokaryotic genomes is imperfect, and errors due to fragmented assemblies, contamination, diverse gene families and mis-assemblies accumulate over the population, leading to profound consequences when analysing the set of all genes found in a species. Here, we introduce Panaroo, a graph-based pangenome clustering tool that is able to account for many of the sources of error introduced during the annotation of prokaryotic genome assemblies. Panaroo is available at https://github.com/gtonkinhill/panaroo.Peer reviewe

Field-induced canting of magnetic moments in GdCo5 at finite temperature : first-principles calculations and high-field measurements

We present calculations and experimental measurements of the temperature-dependent magnetization of a single crystal of GdCo5 in magnetic fields of order 60 T. At zero temperature the calculations, based on density-functional theory in the disordered-local-moment picture, predict a field-induced transition from an antiferromagnetic to a canted alignment of Gd and Co moments at 46.1 T. At higher temperatures the calculations find this critical field to increase along with the zerofield magnetization. The experimental measurements observe this transition to occur between 44–48 T at 1.4 K. Up to temperatures of at least 100 K, the experiments continue to observe the transition; however, at variance with the calculations, no strong temperature dependence of the critical field is apparent. We assign this difference to the inaccurate description of the zero-field magnetization of the calculations at low temperatures, due to the use of classical statistical mechanics. Correcting for this effect, we recover a consistent description of the high-field magnetization of GdCo5 from theory and experiment

Seawater redox variations during the deposition of the Kimmeridge Clay Formation, United Kingdom (Upper Jurassic): evidence from molybdenum isotopes and trace metal ratios

The Kimmeridge Clay Formation (KCF) and its equivalents worldwide represent one of the most prolonged periods of organic carbon accumulation of the Mesozoic. In this study, we use the molybdenum (Mo) stable isotope system in conjunction with a range of trace metal paleoredox proxies to assess how seawater redox varied both locally and globally during the deposition of the KCF. Facies with lower organic carbon contents (TOC 1–7 wt %) were deposited under mildly reducing (suboxic) conditions, while organic-rich facies (TOC &gt;7 wt %) accumulated under more strongly reducing (anoxic or euxinic) local conditions. Trace metal abundances are closely linked to TOC content, suggesting that the intensity of reducing conditions varied repeatedly during the deposition of the KCF and may have been related to orbitally controlled climate changes. Long-term variations in ?98/95Mo are associated with the formation of organic-rich intervals and are related to third-order fluctuations in relative sea level. Differences in the mean ?98/95Mo composition of the organic-rich intervals suggest that the global distribution of reducing conditions was more extensive during the deposition of the Pectinatites wheatleyensis and lower Pectinatites hudlestoni zones than during the deposition of the upper Pectinatites hudlestoni and Pectinatites pectinatus zones. The global extent of reducing conditions during the Kimmerigidan was greater than today but was less widespread than during the Toarcian (Early Jurassic) oceanic anoxic event. This study also demonstrates that the Mo isotope system in Jurassic seawater responded to changes in redox conditions in a manner consistent with its behavior in present-day sedimentary environment