Linear and nonlinear properties of the Goldreich-Schubert-Fricke instability in stellar interiors with arbitrary local radial and latitudinal differential rotation

We investigate the linear and nonlinear properties of the Goldreich-Schubert-Fricke (GSF) instability in stellar radiative zones with arbitrary local (radial and latitudinal) differential rotation. This instability may lead to turbulence that contributes to redistribution of angular momentum and chemical composition in stars. In our local Boussinesq model, we investigate varying the orientation of the shear with respect to the 'effective gravity', which we describe using the angle $\phi$. We first perform an axisymmetric linear analysis to explore the effects of varying $\phi$ on the local stability of arbitrary differential rotations. We then explore the nonlinear hydrodynamical evolution in three dimensions using a modified shearing box. The model exhibits both the diffusive GSF instability, and a non-diffusive instability that occurs when the Solberg-H\{o}iland criteria are violated. We observe the nonlinear development of strong zonal jets ("layering" in the angular momentum) with a preferred orientation in both cases, which can considerably enhance turbulent transport. By varying $\phi$ we find the instability with mixed radial and latitudinal shears transports angular momentum more efficiently (particularly if adiabatically unstable) than cases with purely radial shear $(\phi = 0)$. By exploring the dependence on box size, we find the transport properties of the GSF instability to be largely insensitive to this, implying we can meaningfully extrapolate our results to stars. However, there is no preferred length-scale for adiabatic instability, which therefore exhibits strong box-size dependence. These instabilities may contribute to the missing angular momentum transport required in red giant and subgiant stars and drive turbulence in the solar tachocline.Comment: 26 pages, 17 figures, 4 tables, accepted for publication in MNRAS (28th June 2023

Automated, high accuracy classification of Parkinsonian disorders: a pattern recognition approach

Progressive supranuclear palsy (PSP), multiple system atrophy (MSA) and idiopathic Parkinson’s disease (IPD) can be clinically indistinguishable, especially in the early stages, despite distinct patterns of molecular pathology. Structural neuroimaging holds promise for providing objective biomarkers for discriminating these diseases at the single subject level but all studies to date have reported incomplete separation of disease groups. In this study, we employed multi-class pattern recognition to assess the value of anatomical patterns derived from a widely available structural neuroimaging sequence for automated classification of these disorders. To achieve this, 17 patients with PSP, 14 with IPD and 19 with MSA were scanned using structural MRI along with 19 healthy controls (HCs). An advanced probabilistic pattern recognition approach was employed to evaluate the diagnostic value of several pre-defined anatomical patterns for discriminating the disorders, including: (i) a subcortical motor network; (ii) each of its component regions and (iii) the whole brain. All disease groups could be discriminated simultaneously with high accuracy using the subcortical motor network. The region providing the most accurate predictions overall was the midbrain/brainstem, which discriminated all disease groups from one another and from HCs. The subcortical network also produced more accurate predictions than the whole brain and all of its constituent regions. PSP was accurately predicted from the midbrain/brainstem, cerebellum and all basal ganglia compartments; MSA from the midbrain/brainstem and cerebellum and IPD from the midbrain/brainstem only. This study demonstrates that automated analysis of structural MRI can accurately predict diagnosis in individual patients with Parkinsonian disorders, and identifies distinct patterns of regional atrophy particularly useful for this process

Cretaceous age, composition, and microstructure of pseudotachylyte in the Otago Schist, New Zealand

At Tucker Hill, in Central Otago, New Zealand, a series of pseudotachylyte veins are hosted in quartzofeldspathic schist. Chilled margins, microlites, flow banding, and the crystallisation of mineral phases absent from the host rock provide unequivocal evidence for melting during pseudotachylyte formation. Whole rock analyses of pseudotachylyte reveal c. 3 enrichment of K2O, Ba, and Rb, and similar depletion of Na2O, CaO, Sr, and Eu, as compared to host schist. Formation age of pseudotachylyte is 95.9±1.8 Ma as measured by total fusion 40Ar/39Ar analyses. Stepwise heating of pseudotachylyte matrix yields an excellently defined 40Ar/39Ar plateau age of 96.0±0.3 Ma. These well-defined ages are attributed to the presence of potassium feldspar, low abundance of inherited lithic material from the host rock, and few fluid inclusions containing extraneous Ar. We propose that formation of these pseudotachylyte veins was related to Cretaceous extensional uplift and exhumation of the Otago Schist

Mesoscopic Interference for Metric and Curvature (MIMAC) & Gravitational Wave Detection

A compact detector for space-time metric and curvature is highly desirable. Here we show that quantum spatial superpositions of mesoscopic objects, of the type which would in principle become possible with a combination of state of the art techniques and taking into account the known sources of decoherence, could be exploited to create such a detector. By using Stern-Gerlach (SG) interferometry with masses much larger than atoms, where the interferometric signal is extracted by measuring spins, we show that accelerations as low as $5\times10^{-15}\textrm{ms}^{-2}\textrm{Hz}^{-1/2}$ or better, as well as the frame dragging effects caused by the Earth, could be sensed. Constructing such an apparatus to be non-symmetric would also enable the direct detection of curvature and gravitational waves (GWs). The GW sensitivity scales differently from the stray acceleration sensitivity, a unique feature of MIMAC. We have identified mitigation mechanisms for the known sources of noise, namely Gravity Gradient Noise (GGN), uncertainty principle and electro-magnetic forces. Hence it could potentially lead to a meter sized, orientable and vibrational noise (thermal/seismic) resilient detector of mid (ground based) and low (space based) frequency GWs from massive binaries (the predicted regimes are similar to those targeted by atom interferometers and LISA).Comment: 29 pages, 3 figure

Corn particle size and pelleting influence on growth performance, fecal shedding, and lymph node infection rates of salmonella enterica serovar typhimurium

Ninety-six pigs (initially 13.8 lb.) were used in a 28-d trial to determine the interactive effects between pelleting and particle size on Salmonella serovar Typhimurium shedding and colonization in a young growing pig model. The experiment was a 2 × 2 factorial arrangement consisting of meal or pelleted diets with fine or coarse ground corn. Pigs were fed the diets 1 wk pre-salmonella inoculation and allotted based on weight to one of four dietary treatments. For the main effect of particle size, pigs fed finer ground corn had significantly improved feed efficiency (P0.82). There was no difference in salmonella infection rates of mesenteric lymph nodes obtained on d 28 between treatments or main effects. Finer grinding and meal diets generally improved growth, feed intake, and feed efficiency compared to pigs fed coarser ground or pelleted feeds. However, particle size or diet form did not alter fecal shedding or mesenteric lymph node infection rates of salmonella organisms in our study

Transforaminal Blood Patch for the Treatment of Chronic Headache from Intracranial Hypotension: A Case Report and Review

This case report describes the successful treatment of chronic headache from intracranial hypotension with bilateral transforaminal (TF) lumbar epidural blood patches (EBPs). The patient is a 65-year-old male with chronic postural headaches. He had not had a headache-free day in more than 13 years. Conservative treatment and several interlaminar epidural blood patches were previously unsuccessful. A transforaminal EBP was performed under fluoroscopic guidance. Resolution of the headache occurred within 5 minutes of the procedure. After three months without a headache the patient had a return of the postural headache. A second transforaminal EBP was performed again with almost immediate resolution. The patient remains headache-free almost six months from the time of first TF blood patch. This is the first published report of the use of transforaminal epidural blood patches for the successful treatment of a headache lasting longer than 3 months

The IPD-IMGT/HLA Database

It is 24 years since the IPD-IMGT/HLA Database, http://www.ebi.ac.uk/ipd/imgt/hla/, was first released, providing the HLA community with a searchable repository of highly curated HLA sequences. The database now contains over 35 000 alleles of the human Major Histocompatibility Complex (MHC) named by the WHO Nomenclature Committee for Factors of the HLA System. This complex contains the most polymorphic genes in the human genome and is now considered hyperpolymorphic. The IPD-IMGT/HLA Database provides a stable and user-friendly repository for this information. Uptake of Next Generation Sequencing technology in recent years has driven an increase in the number of alleles and the length of sequences submitted. As the size of the database has grown the traditional methods of accessing and presenting this data have been challenged, in response, we have developed a suite of tools providing an enhanced user experience to our traditional web-based users while creating new programmatic access for our bioinformatics user base. This suite of tools is powered by the IPD-API, an Application Programming Interface (API), providing scalable and flexible access to the database. The IPD-API provides a stable platform for our future development allowing us to meet the future challenges of the HLA field and needs of the community

‘One door closes, a next door opens up somewhere’: The learning of one Olympic synchronised swimmer

Although training in sport is necessary to reach Olympic status, a conditioned body is not the only outcome. Athletes also learn how to be Olympians. This learning involves taking on certain ways of acting, thinking and valuing. Such learning has implications beyond competition, as athletes eventually retire from elite sport and devote their time to other activities. This paper examines processes of learning and transition using the case of Amelia, a former Olympic synchronised swimmer. Through two in-depth interviews, empirical material was generated which focused on the learning that took place during this athlete’s career and after, during her transition to paid employment. A cultural view of learning was used as the theoretical frame to understand the athlete’s experiences. Our reading suggests that the athlete learned in various ways to be productive. Some of these ways of being were useful after retirement; others were less compatible. In fact, Amelia used a two-year period after retirement to reconstruct herself. Key to her eventual successful transition was to distance herself from the sport and to critically reflect upon her sporting experiences. We thus recommend that those involved with high-performance athletes foster a more balanced perspective that acknowledges and promotes ways of being beyond athletic involvement

Cis-Acting Regulation of Brain-Specific ANK3 Gene Expression by a Genetic Variant Associated with Bipolar Disorder

Several genome-wide association studies (GWAS) for bipolar disorder (BD) have found a strong association of the Ankyrin3 (ANK3) gene. This association spans numerous linked single nucleotide polymorphisms (SNPs) in a ~250 kb genomic region overlapping ANK3. The associated region encompasses predicted regulatory elements as well as two of six validated alternative first exons, which encode distinct protein domains at the N-terminus of the protein also known as ankyrin-G (AnkG). Using RNA Ligase-Mediated Rapid Amplification of cDNA Ends (RLM-RACE) to identify novel transcripts in conjunction with a highly sensitive, exon-specific multiplexed mRNA expression assay, we detected differential regulation of distinct ANK3 transcription start sites (TSSs) and coupling of specific 5’ ends with 3’ mRNA splicing events in post-mortem human brain and human stem cell-derived neural progenitors and neurons. Furthermore, allelic variation at the BD–associated SNP rs1938526 correlated with a significant difference in cerebellar expression of a brain-specific ANK3 transcript. These findings suggest a brain-specific cis-regulatory transcriptional effect of ANK3 may be relevant to BD pathophysiology