177 research outputs found
Discovery of a 500 pc shell in the nucleus of Centaurus A
Spitzer Space Telescope mid-infrared images of the radio galaxy Centaurus A
reveal a shell-like, bipolar, structure 500 pc to the north and south of the
nucleus. This shell is seen in 5.8, 8.0 and 24 micron broad-band images. Such a
remarkable shell has not been previously detected in a radio galaxy and is the
first extragalactic nuclear shell detected at mid-infrared wavelengths. We
estimate that the shell is a few million years old and has a mass of order
million solar masses. A conservative estimate for the mechanical energy in the
wind driven bubble is 10^53 erg. The shell could have created by a small few
thousand solar mass nuclear burst of star formation. Alternatively, the
bolometric luminosity of the active nucleus is sufficiently large that it could
power the shell. Constraints on the shell's velocity are lacking. However, if
the shell is moving at 1000 km/s then the required mechanical energy would be
100 times larger.Comment: submitted to ApJ Letter
Strokes of serendipity: community co-curation and engagement with digital heritage
This article explores the potential that community–led digital engagement with heritage holds for stimulating active citizenship through taking responsibility for shared cultural heritage and for fostering long-lasting relationships between local community heritage groups and national museums. Through the lens of a pilot project titled Science Museum: Community-in- Residence, we discovered that — despite working with community groups that were already loyal to and enjoyed existing working ties with the Science Museum in London, U.K — this undertaking proved challenging owing to a range of structural and logistical issues even before the application of digital devices and tools had been considered. These challenges notwithstanding, the pilot found that the creation of time and space for face-to-face dialogue and interactions between the Science Museum and the participating community heritage groups helped to establish the parameters within which digital co-curation can effectively occur. This, in turn, informed the development of a digital prototype with huge potential to enable remote, virtual connectivity to, and interactivity with, conversations about shared heritage. The ultimate goal was two-fold: (a) to help facilitate collaborative sense-making of our shared past, and (b) to aid the building of sustainable institutional and community/public working ties around emerging affinities, agendas and research questions in relation to public history and heritage
On the robustness of the ammonia thermometer
Ammonia inversion lines are often used as probes of the physical conditions
in the dense ISM. The excitation temperature between the first two para
metastable (rotational) levels is an excellent probe of the gas kinetic
temperature. However, the calibration of this ammonia thermometer depends on
the accuracy of the collisional rates with H2. Here we present new collisional
rates for ortho-NH3 and para-NH3 colliding with para-H2 (J=0) and we
investigate the effects of these new rates on the excitation of ammonia.
Scattering calculations employ a new, high accuracy, potential energy surface
computed at the coupled-cluster CCSD(T) level with a basis set extrapolation
procedure. Rates are obtained for all transitions involving ammonia levels with
J <= 3 and for kinetic temperatures in the range 5-100 K. We find that the
calibration curve of the ammonia thermometer -- which relates the observed
excitation temperature between the first two para metastable levels to the gas
kinetic temperature -- does not change significantly when these new rates are
used. Thus, the calibration of ammonia thermometer appears to be robust.
Effects of the new rates on the excitation temperature of inversion and
rotation-inversion transitions are also found to be small.Comment: Accepted for publication in the MNRA
Population Pharmacokinetic Modelling of FE 999049, a Recombinant Human Follicle-Stimulating Hormone, in Healthy Women After Single Ascending Doses
OBJECTIVE: The purpose of this analysis was to develop a population pharmacokinetic model for a novel recombinant human follicle-stimulating hormone (FSH) (FE 999049) expressed from a human cell line of foetal retinal origin (PER.C6(®)) developed for controlled ovarian stimulation prior to assisted reproductive technologies.METHODS: Serum FSH levels were measured following a single subcutaneous FE 999049 injection of 37.5, 75, 150, 225 or 450 IU in 27 pituitary-suppressed healthy female subjects participating in this first-in-human single ascending dose trial. Data was analysed by nonlinear mixed effects population pharmacokinetic modelling in NONMEM 7.2.0.RESULTS: A one-compartment model with first-order absorption and elimination rates was found to best describe the data. A transit model was introduced to describe a delay in the absorption process. The apparent clearance (CL/F) and apparent volume of distribution (V/F) estimates were found to increase with body weight. Body weight was included as an allometrically scaled covariate with a power exponent of 0.75 for CL/F and 1 for V/F.CONCLUSIONS: The single-dose pharmacokinetics of FE 999049 were adequately described by a population pharmacokinetic model. The average drug concentration at steady state is expected to be reduced with increasing body weight
Clonal Hematopoiesis is Associated With Protection From Alzheimer\u27s Disease
Clonal hematopoiesis of indeterminate potential (CHIP) is a premalignant expansion of mutated hematopoietic stem cells. As CHIP-associated mutations are known to alter the development and function of myeloid cells, we hypothesized that CHIP may also be associated with the risk of Alzheimer\u27s disease (AD), a disease in which brain-resident myeloid cells are thought to have a major role. To perform association tests between CHIP and AD dementia, we analyzed blood DNA sequencing data from 1,362 individuals with AD and 4,368 individuals without AD. Individuals with CHIP had a lower risk of AD dementia (meta-analysis odds ratio (OR) = 0.64, P = 3.8 × 1
Neuropathological and Genetic Correlates of Survival and Dementia Onset in Synucleinopathies: A Retrospective Analysis
Background
Great heterogeneity exists in survival and the interval between onset of motor symptoms and dementia symptoms across synucleinopathies. We aimed to identify genetic and pathological markers that have the strongest association with these features of clinical heterogeneity in synucleinopathies.
Methods
In this retrospective study, we examined symptom onset, and genetic and neuropathological data from a cohort of patients with Lewy body disorders with autopsy-confirmed α synucleinopathy (as of Oct 1, 2015) who were previously included in other studies from five academic institutions in five cities in the USA. We used histopathology techniques and markers to assess the burden of tau neurofibrillary tangles, neuritic plaques, α-synuclein inclusions, and other pathological changes in cortical regions. These samples were graded on an ordinal scale and genotyped for variants associated with synucleinopathies. We assessed the interval from onset of motor symptoms to onset of dementia, and overall survival in groups with varying levels of comorbid Alzheimer\u27s disease pathology according to US National Institute on Aging–Alzheimer\u27s Association neuropathological criteria, and used multivariate regression to control for age at death and sex.
Findings
On the basis of data from 213 patients who had been followed up to autopsy and met inclusion criteria of Lewy body disorder with autopsy-confirmed α synucleinopathy, we identified 49 (23%) patients with no Alzheimer\u27s disease neuropathology, 56 (26%) with low-level Alzheimer\u27s disease neuropathology, 45 (21%) with intermediate-level Alzheimer\u27s disease neuropathology, and 63 (30%) with high-level Alzheimer\u27s disease neuropathology. As levels of Alzheimer\u27s disease neuropathology increased, cerebral α-synuclein scores were higher, and the interval between onset of motor and dementia symptoms and disease duration was shorter (p \u3c 0·0001 for all comparisons). Multivariate regression showed independent negative associations of cerebral tau neurofibrillary tangles score with the interval between onset of motor and dementia symptoms (β −4·0, 95% CI −5·5 to −2·6; p \u3c 0·0001; R 2 0·22, p \u3c 0·0001) and with survival (–2·0, −3·2 to −0·8; 0·003; 0·15, \u3c 0·0001) in models that included age at death, sex, cerebral neuritic plaque scores, cerebral α-synuclein scores, presence of cerebrovascular disease, MAPT haplotype, and APOE genotype as covariates.
Interpretation
Alzheimer\u27s disease neuropathology is common in synucleinopathies and confers a worse prognosis for each increasing level of neuropathological change. Cerebral neurofibrillary tangles burden, in addition to α-synuclein pathology and amyloid plaque pathology, are the strongest pathological predictors of a shorter interval between onset of motor and dementia symptoms and survival. Diagnostic criteria based on reliable biomarkers for Alzheimer\u27s disease neuropathology in synucleinopathies should help to identify the most appropriate patients for clinical trials of emerging therapies targeting tau, amyloid-β or α synuclein, and to stratify them by level of Alzheimer\u27s disease neuropathology
Target cell-specific synaptic dynamics of excitatory to inhibitory neuron connections in supragranular layers of human neocortex.
Rodent studies have demonstrated that synaptic dynamics from excitatory to inhibitory neuron types are often dependent on the target cell type. However, these target cell-specific properties have not been well investigated in human cortex, where there are major technical challenges in reliably obtaining healthy tissue, conducting multiple patch-clamp recordings on inhibitory cell types, and identifying those cell types. Here, we take advantage of newly developed methods for human neurosurgical tissue analysis with multiple patch-clamp recordings, post-hoc fluorescent in situ hybridization (FISH), machine learning-based cell type classification and prospective GABAergic AAV-based labeling to investigate synaptic properties between pyramidal neurons and PVALB- vs. SST-positive interneurons. We find that there are robust molecular differences in synapse-associated genes between these neuron types, and that individual presynaptic pyramidal neurons evoke postsynaptic responses with heterogeneous synaptic dynamics in different postsynaptic cell types. Using molecular identification with FISH and classifiers based on transcriptomically identified PVALB neurons analyzed by Patch-seq, we find that PVALB neurons typically show depressing synaptic characteristics, whereas other interneuron types including SST-positive neurons show facilitating characteristics. Together, these data support the existence of target cell-specific synaptic properties in human cortex that are similar to rodent, thereby indicating evolutionary conservation of local circuit connectivity motifs from excitatory to inhibitory neurons and their synaptic dynamics
- …