Rapid subsurface warming and circulation changes of Antarctic coastal waters by poleward shifting winds

The southern hemisphere westerly winds have been strengthening and shifting poleward since the 1950s. This wind trend is projected to persist under continued anthropogenic forcing, but the impact of the changing winds on Antarctic coastal heat distribution remains poorly understood. Here we show that a poleward wind shift at the latitudes of the Antarctic Peninsula can produce an intense warming of subsurface coastal waters that exceeds 2°C at 200-700 m depth. The model simulated warming results from a rapid advective heat flux induced by weakened near-shore Ekman pumping and is associated with weakened coastal currents. This analysis shows that anthropogenically induced wind changes can dramatically increase the temperature of ocean water at ice sheet grounding lines and at the base of floating ice shelves around Antarctica, with potentially significant ramifications for global sea level rise. Key Points Twenty-first century winds drive Antarctic coastal warming and circulation changes The winds cause coastal isotherms to shoal and weaken coastal currents Fine model grid resolution is required to represent the coastal Ekman dynamic

Forensic evidence preservation following an incident of rape: The role of the victim

Background: Rape has a high prevalence in South Africa. The collection of credible and valid forensic evidence is a key legal factor that impacts case trial outcomes. Victim behaviour around the time of the rape can impact the collection and the integrity of forensic evidence, and can have a direct effect on case progression and conviction. Despite the importance of victim behaviour, few studies have been done on the role of victims in preserving forensic evidence. This article discusses how common personal hygiene practices undertaken by rape victims after being raped can impact the quality and validity of forensic evidence. This investigation was done with the aim of elucidating the role of victims in preserving forensic evidence post rape. Methods: This was a descriptive, retrospective clinical audit of all rape victims managed at Robert Mangaliso Sobukwe Hospital forensic unit in South Africa from 01 January 2020 to 31 March 2022. Results: A total of 192 rape cases over the study period were included in this review. The median age of rape victims was 20 years (minimum 2 years; maximum 76 years). The majority (n = 178; 92.7%) of the victims were female. About 44.8% (n = 86) of the victims reported that they had urinated post-rape and prior to forensic examination, 20.8% (n = 40) had changed their clothing, 8.3% (n = 16) had showered, 6.8% (n = 13) had bathed, 4.2% (n = 8) had douched, and only 1.0% (n = 2) had defecated. Only 44 (22.9%) of the victims reported to have ingested alcohol or spiked drinks before the rape. Conclusion: These findings suggest that some rape victims engaged in personal hygiene practices that could militate against forensic evidence preservation. This finding, therefore, indicates the need for public awareness about ways to preserve evidence to the greatest extent possible after an incident of rape. Contribution: We provide simple guidelines for victims on the preservation of forensic evidence following rape and before detailed forensic medical examination and evidence collection

Anomalous damping dependence of the switching time in Fe/FePt bilayer recording media

Gilbert damping plays a significant role in magnetic reversal processes, and it determines the timescale of the switching. Here we investigate the properties of exchange-coupled composite media and the dependence of the switching time on the damping constant of the soft layer using atomistic spin dynamics. For a bilayer Fe/FePt medium, we find an anomalous increase of the switching time with increasing soft layer damping constant. The reversal occurs via a high-temperature exchange spring, and we show that the increase in the switching time is related to a corresponding increase in the time to establish the exchange spring. This phenomenon is delicately balanced in that the switching time increase occurs only in fields close to the coercivity

Manifestation of higher-order inter-granular exchange in magnetic recording media

Exchange coupling between magnetic grains is essential for maintaining the stability of stored information in magnetic recording media. Using an atomistic spin model, we have investigated the coupling between neighbouring magnetic grains where magnetic impurity atoms have migrated into the non-magnetic grain boundary. We find that when the impurity density is low, a biquadratic term in addition to the bilinear term is found to better describe the inter-granular exchange coupling. The temperature dependence of both terms is found to follow a power law behaviour with the biquadratic exchange constant decaying faster than the bilinear. For the increasing grain boundary thickness, the inter-granular exchange reduces and also decays more quickly with temperature. Further simulations of a grain at a bit boundary show an unexpected energy minimum for in-plane magnetisation. This feature is reproduced if the biquadratic exchange term is included

Generalized harmonic formulation in spherical symmetry

In this pedagogically structured article, we describe a generalized harmonic formulation of the Einstein equations in spherical symmetry which is regular at the origin. The generalized harmonic approach has attracted significant attention in numerical relativity over the past few years, especially as applied to the problem of binary inspiral and merger. A key issue when using the technique is the choice of the gauge source functions, and recent work has provided several prescriptions for gauge drivers designed to evolve these functions in a controlled way. We numerically investigate the parameter spaces of some of these drivers in the context of fully non-linear collapse of a real, massless scalar field, and determine nearly optimal parameter settings for specific situations. Surprisingly, we find that many of the drivers that perform well in 3+1 calculations that use Cartesian coordinates, are considerably less effective in spherical symmetry, where some of them are, in fact, unstable.Comment: 47 pages, 15 figures. v2: Minor corrections, including 2 added references; journal version

Spin-lattice dynamics model with angular momentum transfer for canonical and microcanonical ensembles

A unified model of molecular and atomistic spin dynamics is presented enabling simulations both in microcanonical and canonical ensembles without the necessity of additional phenomenological spin damping. Transfer of energy and angular momentum between the lattice and the spin systems is achieved by a phenomenological coupling term representing the spin-orbit interaction. The characteristic spectra of the spin and phonon systems are analyzed for different coupling strength and temperatures. The spin spectral density shows magnon modes together with the uncorrelated noise induced by the coupling to the lattice. The effective damping parameter is investigated showing an increase with both coupling strength and temperature. The model paves the way to understanding magnetic relaxation processes beyond the phenomenological approach of the Gilbert damping and the dynamics of the energy transfer between lattice and spins

Challenges of accountability and development in Nigeria: An auto-regressive distributed lag approach

Purpose The purpose of this paper is to examine the challenges of accountability and development in Nigeria. In the literature, corruption is seen as an indicator of a lack of political accountability in most countries of the world, especially in less developed countries such as Nigeria. The Nigerian Government has taken several actions to address the problems of bad governance and corruption that have impeded economic development, but unfortunately these measures have not yielded the desired results. Design/methodology/approach Thus, this study examined accountability and developmental issues in Nigeria using secondary data and then made use of the auto-regressive distributed lag econometric technique to analyze the data. Findings The results from the study found that a rise in total government expenditure poses a danger of reducing Nigeria’s economic development in the long run and that control of corruption and political (the institutional variables) has a direct and significant effect on Nigeria’s economic development. Originality/value Therefore, upon these findings, this paper recommended that for Nigeria to experience development, corruption should be eliminated, and the Nigerian Government should spend on viable projects and economic activities that will be beneficial to the populace and the society at large and hence bring about economic development. Accountability is the hallmark of a prudent government that ensures efficient management of resources and transparency in the utilization of funds by the government. The absence of accountability mechanism allows corruption to thrive, which hinders the developmental process

Novel genetic loci associated with hippocampal volume

The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness