Solar Wakes of Dark Matter Flows

We analyze the effect of the Sun's gravitational field on a flow of cold dark matter (CDM) through the solar system in the limit where the velocity dispersion of the flow vanishes. The exact density and velocity distributions are derived in the case where the Sun is a point mass. The results are extended to the more realistic case where the Sun has a finite size spherically symmetric mass distribution. We find that regions of infinite density, called caustics, appear. One such region is a line caustic on the axis of symmetry, downstream from the Sun, where the flow trajectories cross. Another is a cone-shaped caustic surface near the trajectories of maximum scattering angle. The trajectories forming the conical caustic pass through the Sun's interior and probe the solar mass distribution, raising the possibility that the solar mass distribution may some day be measured by a dark matter detector on Earth. We generalize our results to the case of flows with continuous velocity distributions, such as that predicted by the isothermal model of the Milky Way halo.Comment: 30 pages, 8 figure

Toward an internally consistent astronomical distance scale

Accurate astronomical distance determination is crucial for all fields in astrophysics, from Galactic to cosmological scales. Despite, or perhaps because of, significant efforts to determine accurate distances, using a wide range of methods, tracers, and techniques, an internally consistent astronomical distance framework has not yet been established. We review current efforts to homogenize the Local Group's distance framework, with particular emphasis on the potential of RR Lyrae stars as distance indicators, and attempt to extend this in an internally consistent manner to cosmological distances. Calibration based on Type Ia supernovae and distance determinations based on gravitational lensing represent particularly promising approaches. We provide a positive outlook to improvements to the status quo expected from future surveys, missions, and facilities. Astronomical distance determination has clearly reached maturity and near-consistency.Comment: Review article, 59 pages (4 figures); Space Science Reviews, in press (chapter 8 of a special collection resulting from the May 2016 ISSI-BJ workshop on Astronomical Distance Determination in the Space Age

From isolation to integration The development of roads in the Northern Highlands of Scotland 1800-1850

Available from British Library Document Supply Centre-DSC:DXN046493 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Tau immunohistochemistry in acute brain injury

Epidemiological studies have identified a history of head injury as a risk factor for Alzheimer's disease. However, the neuropathological mechanism underlying this relationship is as yet unclear. Neuronal cytoskeletal changes in the form of neurofibrillary tangles and neuropil threads have recently been demonstrated in young men who had sustained repetitive head injury and subsequently died in their 20s. In addition, recent experimental studies have found accumulation of tau within neuronal somata and damaged axons following diffuse brain injury. We hypothesized that tau-immunoreactive tangles may be present in the brains of patients who died after a single acute blunt head injury. A total of 45 cases of fatal head injury were immunostained for tau. They comprised nine groups (n = 5 for each group) separated by age (0–19 years, 20–50 years, 50 + years) and survival time (< 24 h, 24 h?1 week, 1 week?1 month) and were compared with age-matched controls. Subtle alterations in tau immunoreactivity, for example, in oligodendrocytes, were present in some head injury cases but not controls. However, neurofibrillary tangles did not appear more prevalent after traumatic brain injury (TBI) when compared with age-matched controls. Although alterations in tau immunoreactivity may occur which warrant further study, neurofibrillary tangles were not more prevalent after a single fatal episode of TBI

Association of APOE e4 and cerebrovascular pathology in traumatic brain injury

Background: Previous studies have found the e4 allele of the apolipoprotein E gene ( APOE e4) is associated with an unfavourable outcome after head injury, but this has not been related to specific pathological features. Objectives: This study tested the postulate that head injured patients with APOE e4, amounting to approximately a third of the population, are selectively predisposed to one or more of the different pathological features that constitute the response to traumatic brain injury (TBI), and that this underlies the association of APOE e4 with poor clinical outcome. Methods: Included in the study were 239 fatal cases of TBI (1987-1999) for which APOE genotypes were determined from archival tissue. For each case, specific pathological features of trauma were recorded by researchers blinded to the APOE e4 status. Of the 239 cases examined, 83 (35%) were APOE e4 carriers and 156 (65%) were non-carriers. Results: Possession of APOE e4 was associated with a greater incidence of moderate or severe contusions (42% v 30% for carriers versus e4 non-carriers; p = 0.05) and there was a trend towards a greater incidence of severe ischaemic brain damage (54% v 42%; p = 0.08). Significant differences were not noted between the other pathological features examined. Conclusions: Possession of APOE e4 is associated with a greater incidence of moderate/severe contusional injury and severe ischaemic brain damage in fatal cases of TBI. This may be relevant to the relatively poor outcome from traumatic brain injury in patients with APOE e4 identified in clinical studie

Cerebral amyloid angiopathy in traumatic brain injury: association with apolipoprotein E genotype

Objective: In view of the association of the apolipoprotein E (APOE) {varepsilon}4 allele with poor outcome after traumatic brain injury we determined the frequency of cerebral amyloid angiopathy (CAA) and the extent of haemorrhagic pathology in relation to APOE genotype in an autopsy series of 88 head injured cases.Methods: Tissue sections from the frontal and temporal lobes were immunostained for amyloid-ß peptide (Aß) and stained for Congo red to identify vascular amyloid pathology. A semiquantitative assessment of contusions, the total contusion index, was used to estimate the severity of the haemorrhagic pathology. APOE genotypes were determined by polymerase chain reaction of genomic DNA extracted from paraffin embedded tissue sections.Results: CAA was present in 7/40 (18%) {varepsilon}4 carriers compared with 1/48 (2%) non-{varepsilon}4 carriers (p = 0.021, 95% confidence interval (CI) for difference in proportions with CAA 3% to 29%) with 6/40 (4 with CAA) {varepsilon}4 carriers being homozygotes. Thus the risk of having CAA for {varepsilon}4 carriers was 8.4 times that for the non-{varepsilon}4 carriers. However, there was no clear tendency for patients with CAA to have more severe or more numerous contusions (median contusion index 19 (CAA) v 14.5, p = 0.23, 95% CI for difference in medians –5 to 14).Conclusions: Presence of CAA in head injured cases was significantly associated with possession of an APOE {varepsilon}4 allele but not with the severity of contusions

The neuroinflammatory response in humans after traumatic brain injury

Aims: Traumatic brain injury is a significant cause of morbidity and mortality worldwide. An epidemiological association between head injury and long-term cognitive decline has been described for many years and recent clinical studies have highlighted functional impairment within 12 months of a mild head injury. In addition chronic traumatic encephalopathy is a recently described condition in cases of repetitive head injury. There are shared mechanisms between traumatic brain injury and Alzheimer's disease, and it has been hypothesized that neuroinflammation, in the form of microglial activation, may be a mechanism underlying chronic neurodegenerative processes after traumatic brain injury.Methods: This study assessed the microglial reaction after head injury in a range of ages and survival periods, from <24-h survival through to 47-year survival. Immunohistochemistry for reactive microglia (CD68 and CR3/43) was performed on human autopsy brain tissue and assessed ‘blind’ by quantitative image analysis. Head injury cases were compared with age matched controls, and within the traumatic brain injury group cases with diffuse traumatic axonal injury were compared with cases without diffuse traumatic axonal injury.Results: A major finding was a neuroinflammatory response that develops within the first week and persists for several months after traumatic brain injury, but has returned to control levels after several years. In cases with diffuse traumatic axonal injury the microglial reaction is particularly pronounced in the white matter.Conclusions: These results demonstrate that prolonged microglial activation is a feature of traumatic brain injury, but that the neuroinflammatory response returns to control levels after several years

Short chain lead (II) alkanoates as ionic liquids and glass formers: A d.s.c., X-ray diffraction and FTIR spectroscopy study

Three members of the lead (II) n-alkanoates (from etanoate to n-butanoate) have been synthesized, purified and studied by d.s.c., Xray diffraction, and FTIR spectroscopy. Lead (II) acetate, propanoate, and butanoate present only a melting transition at T = (452.6, 398.2, and 346.5) K, with DfH = (16.0, 13.1, and 15.6) kJ Æ mol1, and DfS = (35.3, 32.8, and 45.1) J Æ mol1 Æ K1, respectively. These temperature data correct to a great extent the historical values reported in the literature. These three members readily quench into a glass state. Their corresponding Tg values are (314.4, 289.0, and 274.9) K, respectively, measured by d.s.c. at a heating rate of 5 K Æ min-1

Association of the androgen receptor CAG repeat polymorphism with Alzheimer's disease in men

We examined the CAG repeat polymorphism in exon 1 of the androgen receptor (AR) in an Oxford cohort of 150 cases (101 men) of definite or probable Alzheimer's disease (AD) and 190 elderly controls (140 men). We found that short alleles (< or = 20 CAG repeats) were associated with AD (adjusted odds ratio = 2.5, 95% confidence intervals: 1.2-5.0) in men, but not in women. This association appeared stronger in early-onset AD (< 65 years). We conclude that this AR polymorphism is of potential relevance to the risk of AD in men