Hidden magnetism uncovered in a charge ordered bilayer kagome material ScV6Sn6.

Charge ordered kagome lattices have been demonstrated to be intriguing platforms for studying the intertwining of topology, correlation, and magnetism. The recently discovered charge ordered kagome material ScV6Sn6 does not feature a magnetic groundstate or excitations, thus it is often regarded as a conventional paramagnet. Here, using advanced muon-spin rotation spectroscopy, we uncover an unexpected hidden magnetism of the charge order. We observe an enhancement of the internal field width sensed by the muon ensemble, which takes place within the charge ordered state. More importantly, the muon spin relaxation rate below the charge ordering temperature is substantially enhanced by applying an external magnetic field. Taken together with the hidden magnetism found in AV3Sb5 (A = K, Rb, Cs) and FeGe kagome systems, our results suggest ubiqitous time-reversal symmetry-breaking in charge ordered kagome lattices.

Local Electronic Structure and Dynamics of Muon-Polaron Complexes in Fe_{2}O_{3}.

We perform detailed muon spin rotation (µSR) measurements in the classic antiferromagnet Fe_{2}O_{3} and explain the spectra by considering dynamic population and dissociation of charge-neutral muon-polaron complexes. We show that charge-neutral muon states in Fe_{2}O_{3}, despite lacking the signatures typical of charge-neutral muonium centers in nonmagnetic materials, have a significant impact on the measured µSR frequencies and relaxation rates. Our identification of such polaronic muon centers in Fe_{2}O_{3} suggests that isolated hydrogen (H) impurities form analogous complexes, and that H interstitials may be a source of charge carrier density in Fe_{2}O_{3}.

Effects of the Hubbard U on density functional-based predictions of BiFeO3 properties.

First principles studies of multiferroic materials, such as bismuth ferrite (BFO), require methods that extend beyond standard density functional theory (DFT). The DFT + U method is one such extension that is widely used in the study of BFO. We present a systematic study of the effects of the U parameter on the structural, ferroelectric and electronic properties of BFO. We find that the structural and ferroelectric properties change negligibly in the range of U typically considered for BFO (3-5 eV). In contrast, the electronic structure varies significantly with U. In particular, we see large changes to the character and curvature of the valence band maximum and conduction band minimum, in addition to the expected increase in band gap, as U increases. Most significantly, we find that the [Formula: see text]/[Formula: see text] ordering at the conduction band minimum inverts for U values larger than 4 eV. We therefore recommend a U value of at most 4 eV to be applied to the Fe d orbitals in BFO. More generally, this study emphasises the need for systematic investigations of the effects of the U parameter not merely on band gaps but on the electronic structure as a whole, especially for strongly correlated materials.

Effects of chronic deoxynivalenol exposure on p53 heterozygous and p53 homozygous mice.

Deoxynivalenol (DON) is a secondary metabolite associated with Fusarium species pathogenic to important food crops. A two-year feeding study reported that DON was non-carcinogenic in B6C3F1 mice. The present study was conducted to further characterize the chronic effects of DON by exposing cancer-prone transgenic p53 heterozygous (p53+/-) male mice and p53 homozygous (p53+/+) male mice to 0, 1, 5, or 10 mg DON/kg in diet for 26 weeks. Gross and microscopic organ-specific neoplastic and non-neoplastic changes and expression profiles of key hepatic and renal genes were assessed. Few toxicologic differences between p53+/+ and p53+/- mice were observed, and no tumours were observed due to DON. The results indicated that DON was non-carcinogenic and that reduced expression of the p53 gene did not play a key role in responses to DON toxicity. The lack of inflammatory and proliferative lesions in mice may be attributed to the anorectic effects of DON, which resulted in dose-dependent reductions in body weight in p53+/+ and p53+/- mice. Hepatic and renal gene expression analyses confirmed that chronic exposure to DON was noninflammatory. The effects of 26-week DON exposure on p53+/+ and p53+/-mice were consistent with those previously seen in B6C3F1 mice exposed to DON for two years.

Nevirapine hypersensitivity.

Treatment of HIV-1 infections with nevirapine is associated with skin and liver toxicity. These two organ toxicities range from mild to severe, in rare cases resulting in life-threatening liver failure or toxic epidermal necrolysis. The study of the mechanistic steps leading to nevirapine-induced skin rash has been facilitated by the discovery of an animal model in which nevirapine causes a skin rash in rats that closely mimics the rash reported in patients. The similarity in characteristics of the rash between humans and rats strongly suggests that the basic mechanism is the same in both. The rash is clearly immune-mediated in rats, and partial depletion of CD4(+) T cells, but not CD8(+) T cells, is protective. We have demonstrated that the rash is related to the 12-hydroxylation of nevirapine rather than to the parent drug. This is presumably because the 12-hydroxy metabolite can be converted to a reactive quinone methide in skin, but that remains to be demonstrated. Although the rash is clearly related to the 12-hydroxy metabolite rather than the parent drug, cells from rechallenged animals respond ex vivo to the parent drug by producing cytokines such as interferon-gamma with little response to the 12-hydroxy metabolite, even when the rash was induced by treatment with the metabolite rather than the parent drug. This indicates that the response of T cells in vitro cannot be used to determine what caused an immune response. We are now studying the detailed steps by which the 12-hydroxy metabolite induces an immune response and skin rash. This animal model provides a unique tool to study the mechanistic details of an idiosyncratic drug reaction; however, it is likely that there are significant differences in the mechanisms of different idiosyncratic drug reactions, and therefore the results of these studies cannot safely be generalized to all idiosyncratic drug reactions.

Catching life: the contribution of arts initiatives to recovery approaches in mental health.

This paper draws on a qualitative study that was undertaken as part of a national research study to assess the impact of participatory arts provision for people with mental health needs. It explores how arts and mental health projects may facilitate some of the key elements of what has been termed a 'recovery approach' in mental health. It is argued that it is precisely these elements--the fostering of hope, creating a sense of meaning and purpose, developing new coping mechanisms and rebuilding identities--which are hard to standardize and measure, yet may be the most profound and significant outcomes of participation in such projects. Therefore, in the context of a growing emphasis on recovery-orientated mental health services, while not necessarily being appropriate for all service users, arts and mental health initiatives could make an essential contribution to the future of mental health and social care provision.

Some effects of cyproterone and cyproterone acetate on the reproductive physiology of the male rat.

Male rats were treated with 5 or 20 mg cyproterone acetate/kg/day or 20 mg cyproterone/rat/day for 1, 2, 3, 4, or 5 weeks. There was some reduction in fertility with both compounds, the maximum effect occurring after 5 weeks with the higher dose of cyproterone acetate and after 2 weeks with cyproterone. A significant increase in testosterone levels was found after treatment with the high dose of cyproterone acetate by 1 week and with cyproterone by 2 weeks. Dose-dependent atrophy of the seminal vesicles occurred after treatment with cyproterone acetate; with cyproterone atrophy occurred at 1 and 2 weeks but approximated to control values at 3, 4 and 5 weeks. Epididymal weights were reduced with the high dose of cyproterone acetate but the low dose had little effect. Reduction in the weight of the testes was only observed after 5 weeks of treatment with the high dose of cyproterone acetate. Since plasma testosterone levels were not depressed below normal values, accessory sex organ regression evidently resulted from the local antiandrogenic action of the drugs. There was some indication of interference with the secretory and absorptive activity of the lining cells of the epididymis but in general treatment with either steroid caused only relatively small and variable changes in the composition of epididymal plasma.

The effects of alpha-chlorohydrin on the composition of rat and rabbit epididymal plasma: a possible explanation of species difference.

The relationship between the antifertility effect of alpha-chlorohydrin and changes in composition of luminal plasma from the cauda epididymidis of rats and rabbits has been investigated. At each dose regimen studied, the fertilizing capacity of rats treated with alpha-chlorohydrin was reduced to zero. The levels of sodium, potassium, glycerylphosphorylcholine (GPC), acid phosphatase and alkaline phosphatase in epididymal plasma were not markedly affected by drug treatment. The most noticeable change was a considerable increase in the concentration of lactic dehydrogenase (LDH) at all dose levels and of glutamic-oxaloacetic transaminase (GOT) after 7 days of treatment with 8 and 16 mg/kg. The effect of cold shock on the composition of epididymal plasma showed that LDH and GOT are, at least in part, derived from spermatozoa. In contrast, alpha-chlorohydrin did not have an antifertility action in the rabbit, and the only notable change in the compositon of epididymal plasma was an increase in the level of GPC. These results provide evidence that, in the rat, alpha-chlorohydrin or a metabolite primarily exerts its antifertility effect by a direct action on the spermatozoa, whilst in the rabbit a barrier may exist to the entrance of the drug into the lumen of the epididymal duct.

The temporal relationship between the secretion of luteinizing hormone and testosterone in man.

It has been suggested recently that testosterone secretion by the human testis may be controlled by factors other than luteinizing hormone (LH). In order to re-examine this hypothesis, plasma LH and testosterone concentrations were determined throughout the day in eight studies. A new method of data analysis revealed that the levels of the two hormones were closely related, but that the testicular response to LH was sluggish. These results explain some inconsistencies in the literature. It was demonstrated that average values for LH varied throughout the day, with a morning maximum and an evening minimum. It was also shown that injections of LH releasing hormone in man resulted in an increase in plasma testosterone above control levels. These results are consistent with the concept that LH controls the major changes in testosterone secretion in men. They do not exclude, however, the possible existence of other factors which might affect the peripheral concentration of testosterone, such as changes in testicular blood flow.