Unanticipated results in the uranium niobium alloy system

The uranium niobium binary alloy system exhibits a rich collection of phenomena for study. The composition range from 0 wt.% Nb to 10 wt.% Nb exhibits multiple crystallographic phases with interesting properties such as superconductivity, charge density waves and shape memory effects. We have measured the resistivity and heat capacity as a function of temperature from 2 to 325K in the above composition range in an effort to map out the phase boundaries of interest. Surprisingly the temperature dependence of the resistivity transitions from metallic (decreasing with decreasing temperature) to nonmetallic (increasing with decreasing temperature). It is not clear if the nonmetallic resistivity is caused by strongly correlated electronic effects or is the result of some other effect such as disorder driven scattering

Magnetism and superconductivity of uranium and intermetallic compounds

Heat capacity, resistivity, and phonon density of states have been measured on uranium and reported already. Many of the results are on single crystals of purity that has been unavailable before. Some intermetallic compounds have been measured that are in the class of so-called heavy-fermion materials. We present here the latest results along with a discussion of the occurrence of superconductivity or magnetism in these materials

Clinical and neuroanatomical signatures of tissue pathology in frontotemporal lobar degeneration

Relating clinical symptoms to neuroanatomical profiles of brain damage and ultimately to tissue pathology is a key challenge in the field of neurodegenerative disease and particularly relevant to the heterogeneous disorders that comprise the frontotemporal lobar degeneration spectrum. Here we present a retrospective analysis of clinical, neuropsychological and neuroimaging (volumetric and voxel-based morphometric) features in a pathologically ascertained cohort of 95 cases of frontotemporal lobar degeneration classified according to contemporary neuropathological criteria. Forty-eight cases (51%) had TDP-43 pathology, 42 (44%) had tau pathology and five (5%) had fused-in-sarcoma pathology. Certain relatively specific clinicopathological associations were identified. Semantic dementia was predominantly associated with TDP-43 type C pathology; frontotemporal dementia and motoneuron disease with TDP-43 type B pathology; young-onset behavioural variant frontotemporal dementia with FUS pathology; and the progressive supranuclear palsy syndrome with progressive supranuclear palsy pathology. Progressive non-fluent aphasia was most commonly associated with tau pathology. However, the most common clinical syndrome (behavioural variant frontotemporal dementia) was pathologically heterogeneous; while pathologically proven Pick's disease and corticobasal degeneration were clinically heterogeneous, and TDP-43 type A pathology was associated with similar clinical features in cases with and without progranulin mutations. Volumetric magnetic resonance imaging, voxel-based morphometry and cluster analyses of the pathological groups here suggested a neuroanatomical framework underpinning this clinical and pathological diversity. Frontotemporal lobar degeneration-associated pathologies segregated based on their cerebral atrophy profiles, according to the following scheme: asymmetric, relatively localized (predominantly temporal lobe) atrophy (TDP-43 type C); relatively symmetric, relatively localized (predominantly temporal lobe) atrophy (microtubule-associated protein tau mutations); strongly asymmetric, distributed atrophy (Pick's disease); relatively symmetric, predominantly extratemporal atrophy (corticobasal degeneration, fused-in-sarcoma pathology). TDP-43 type A pathology was associated with substantial individual variation; however, within this group progranulin mutations were associated with strongly asymmetric, distributed hemispheric atrophy. We interpret the findings in terms of emerging network models of neurodegenerative disease: the neuroanatomical specificity of particular frontotemporal lobar degeneration pathologies may depend on an interaction of disease-specific and network-specific factors

ApoE4 lowers age at onset in patients with frontotemporal dementia and tauopathy independent of amyloid-β copathology.

INTRODUCTION: Apolipoprotein E (ApoE) is the most important genetic risk factor for Alzheimer's disease (AD), with ApoE4 thought to enhance and accelerate amyloid-β (Aβ) pathology. ApoE4 has recently been described to increase neurodegeneration in a mouse model of frontotemporal dementia (FTD), in vitro, and in patients, demonstrating that ApoE4 modifies tauopathy independently of Aβ. This raises the question whether ApoE genotype also modifies the clinical phenotype in patients with FTD with tau pathology. METHODS: We analyzed 704 patients with FTD, including a genetically and neuropathologically confirmed subset, and 452 healthy elderly controls. We compared ApoE4 genotype frequency and age at onset in tau+ or TDP43+ FTD patients with or without Aβ copathology. RESULTS: The ApoE4 genotype lowered age at onset in patients with FTD and tau pathology, particularly once accounting for confounding effects of Aβ pathology. DISCUSSION: We conclude that ApoE4 accelerates neurodegeneration in FTD patients with MAPT mutations or FTLD-tau pathology, independent of Aβ

Homozygosity for the C9orf72 GGGGCC repeat expansion in frontotemporal dementia

An expanded hexanucleotide repeat in the C9orf72 gene is the most common genetic cause of frontotemporal dementia and amyotrophic lateral sclerosis (c9FTD/ALS). We now report the first description of a homozygous patient and compare it to a series of heterozygous cases. The patient developed early-onset frontotemporal dementia without additional features. Neuropathological analysis showed c9FTD/ALS characteristics, with abundant p62-positive inclusions in the frontal and temporal cortices, hippocampus and cerebellum, as well as less abundant TDP-43-positive inclusions. Overall, the clinical and pathological features were severe, but did not fall outside the usual disease spectrum. Quantification of C9orf72 transcript levels in post-mortem brain demonstrated expression of all known C9orf72 transcript variants, but at a reduced level. The pathogenic mechanisms by which the hexanucleotide repeat expansion causes disease are unclear and both gain- and loss-of-function mechanisms may play a role. Our data support a gain-of-function mechanism as pure homozygous loss of function would be expected to lead to a more severe, or completely different clinical phenotype to the one described here, which falls within the usual range. Our findings have implications for genetic counselling, highlighting the need to use genetic tests that distinguish C9orf72 homozygosity

Mammal responses to global changes in human activity vary by trophic group and landscape

Wildlife must adapt to human presence to survive in the Anthropocene, so it is critical to understand species responses to humans in different contexts. We used camera trapping as a lens to view mammal responses to changes in human activity during the COVID-19 pandemic. Across 163 species sampled in 102 projects around the world, changes in the amount and timing of animal activity varied widely. Under higher human activity, mammals were less active in undeveloped areas but unexpectedly more active in developed areas while exhibiting greater nocturnality. Carnivores were most sensitive, showing the strongest decreases in activity and greatest increases in nocturnality. Wildlife managers must consider how habituation and uneven sensitivity across species may cause fundamental differences in human–wildlife interactions along gradients of human influence.Peer reviewe

Domain Boundary Engineering in Ferroic and Multiferroic Materials: A Simple Introduction

Multiferroic behavior is commonly described as a bulk phenomenon where, at least, two of the three ferroic properties, ferromagnetism, ferroelectricity, and ferroelasticity, coincide. This notion is enlarged to contain as another “useful” property electrical conductivity. While bulk applications are potentially useful, we describe the recent development where the same properties are restricted to domain boundaries or interfaces, while the adjacent domains are not active elements themselves. This means that the information is restricted to thin, nearly two-dimensional slabs of some 2 nm thickness. The information density is, thus, extremely high, while conducting interfaces can serve as wires to connect the active elements. In this chapter, we discuss the underlying physical principles for the “engineering” of interfacial multiferroics

Elastic softening of metamict titanite CaTiSiO5: Radiation damage and annealing

We have measured the elastic response of radiation-damaged titanite, CaTiSiO5, as a function of thermal annealing. We estimate the bulk modulus of the damaged samples (~24% amorphous) to be 85 GPa, which is much softer than for undamaged crystalline titanite [131.4 GPa; Angel et al. (1999)]. Conversely, the lowest shear modulus of the radiation-damaged material is 52–58 GPa, which is harder that of the undamaged titanite, 46–52 GPa. The bulk and shear moduli of the radiation-damaged materials are close to those of thermal titanite glass, Bglass ≈ 75 GPa and Gglass ≈ 47 GPa, and are much smaller than expected based on other radiation-damaged materials such as zircon (ZrSiO4). Surprisingly, annealing of the damaged titanite in the range 600 < T < 1000 K leads to additional massive softening of the shear moduli. During annealing the shear modulus of titanite sample 1 softened from 58 to 29 GPa, and sample 2 softened from 52 to 19 GPa. The temperature range for the softening coincides with that found for crystallization of the amorphous regions, as measured previously by diffraction and spectroscopic methods. In contrast to the huge softening of the ultrasonically measured shear modulus, the calorimetrically measured Debye temperatur