74 research outputs found
Measuring the growth rate of structure with Type IA Supernovae from LSST
We investigate measuring the peculiar motions of galaxies up to using
Type Ia supernovae (SNe Ia) from LSST, and predict the subsequent constraints
on the growth rate of structure. We consider two cases. Our first is based on
measurements of the volumetric SNe Ia rate and assumes we can obtain
spectroscopic redshifts and light curves for varying fractions of objects that
are detected pre-peak luminosity by LSST (some of which may be obtained by LSST
itself and others which would require additional follow-up). We find that these
measurements could produce growth rate constraints at that
significantly outperform those using Redshift Space Distortions (RSD) with DESI
or 4MOST, even though there are fewer objects. For our second
case, we use semi-analytic simulations and a prescription for the SNe Ia rate
as a function of stellar mass and star formation rate to predict the number of
LSST SNe IA whose host redshifts may already have been obtained with the
Taipan+WALLABY surveys, or with a future multi-object spectroscopic survey. We
find and SN Ia with host redshifts for these cases
respectively. Whilst this is only a fraction of the total LSST-detected SNe Ia,
they could be used to significantly augment and improve the growth rate
constraints compared to only RSD. Ultimately, we find that combining LSST SNe
Ia with large numbers of galaxy redshifts will provide the most powerful probe
of large scale gravity in the regime over the coming decades.Comment: 12 pages, 1 table, 5 figures. Accepted for publication in ApJ. The
Fisher matrix forecast code used in this paper can be found at:
https://github.com/CullanHowlett/PV_fisher. Updated to fix error in Eq. 1
(thanks to Eric Linder for pointing this out
CMB power spectrum parameter degeneracies in the era of precision cosmology
Cosmological parameter constraints from the CMB power spectra alone suffer
several well-known degeneracies. These degeneracies can be broken by numerical
artefacts and also a variety of physical effects that become quantitatively
important with high-accuracy data e.g. from the Planck satellite. We study
degeneracies in models with flat and non-flat spatial sections, non-trivial
dark energy and massive neutrinos, and investigate the importance of various
physical degeneracy-breaking effects. We test the CAMB power spectrum code for
numerical accuracy, and demonstrate that the numerical calculations are
accurate enough for degeneracies to be broken mainly by true physical effects
(the integrated Sachs-Wolfe effect, CMB lensing and geometrical and other
effects through recombination) rather than numerical artefacts. We quantify the
impact of CMB lensing on the power spectra, which inevitably provides
degeneracy-breaking information even without using information in the
non-Gaussianity. Finally we check the numerical accuracy of sample-based
parameter constraints using CAMB and CosmoMC. In an appendix we document recent
changes to CAMB's numerical treatment of massive neutrino perturbations, which
are tested along with other recent improvements by our degeneracy exploration
results.Comment: 27 pages, 28 figures. Latest CAMB version available from
http://camb.info/. Reduced number of figures, plot legend corrected and minor
edits to match published versio
Patterns of predation and meat-eating by chacma baboons in an Afromontane environment
Meat-eating among non-human primates has been well documented but its prevalence among Afromontane baboons is understudied. In this study we report the predatory and meat-eating behaviours of a habituated group of gray-footed chacma baboons (Papio ursinus griseipes) living in an Afromontane environment in South Africa. We calculated a vertebrate-eating rate of 1 every 78.5 hours, increasing to 58.1 hours when unsuccessful predation attempts were included. A key food source was young antelopes, particularly bushbuck (Tragelaphus scriptus), which were consumed once every 115 observation hours. Similar to other baboon research sites, predations seemed mostly opportunistic, adult males regularly scrounged and monopolised prey, there was no evidence they used an active kill bite, and active sharing was absent. This is the first baboon study to report predation of rock python (Python sebae) eggs and likely scavenging of a leopard (Panthera pardus) kill (bushbuck) cached in a tree. We also describe several scramble kleptoparasitism events, tolerating active defence from antelope parents, and the baboons inhibiting public information about predations. In the latter case, baboons with meat often hid beyond the periphery of the group, reducing the likelihood of scrounging by competitors. This often led to prey carcasses being discarded without being fully exploited and potentially providing resources to scavengers. We also highlight the absence of encounters with numerous species, suggesting the baboons are a key component of several species’ landscapes of fear. Given these findings it seems likely that their ecological role in the Soutpansberg has been undervalued, and such conclusions may also hold for other baboon populations
Reduction in BACE1 decreases body weight, protects against diet-induced obesity and enhances insulin sensitivity in mice
Insulin resistance and impaired glucose homoeostasis are important indicators of Type 2 diabetes and are early risk factors of AD (Alzheimer's disease). An essential feature of AD pathology is the presence of BACE1 (β-site amyloid precursor protein-cleaving enzyme 1), which regulates production of toxic amyloid peptides. However, whether BACE1 also plays a role in glucose homoeostasis is presently unknown. We have used transgenic mice to analyse the effects of loss of BACE1 on body weight, and lipid and glucose homoeostasis. BACE1−/− mice are lean, with decreased adiposity, higher energy expenditure, and improved glucose disposal and peripheral insulin sensitivity than wild-type littermates. BACE1−/− mice are also protected from diet-induced obesity. BACE1-deficient skeletal muscle and liver exhibit improved insulin sensitivity. In a skeletal muscle cell line, BACE1 inhibition increased glucose uptake and enhanced insulin sensitivity. The loss of BACE1 is associated with increased levels of UCP1 (uncoupling protein 1) in BAT (brown adipose tissue) and UCP2 and UCP3 mRNA in skeletal muscle, indicative of increased uncoupled respiration and metabolic inefficiency. Thus BACE1 levels may play a critical role in glucose and lipid homoeostasis in conditions of chronic nutrient excess. Therefore strategies that ameliorate BACE1 activity may be important novel approaches for the treatment of diabetes
Probing the neutrino mass hierarchy with CMB weak lensing
We forecast constraints on cosmological parameters with primary CMB
anisotropy information and weak lensing reconstruction with a future
post-Planck CMB experiment, the Cosmic Origins Explorer (COrE), using
oscillation data on the neutrino mass splittings as prior information. Our MCMC
simulations in flat models with a non-evolving equation-of-state of dark energy
w give typical 68% upper bounds on the total neutrino mass of 0.136 eV and
0.098 eV for the inverted and normal hierarchies respectively, assuming the
total summed mass is close to the minimum allowed by the oscillation data for
the respective hierarchies (0.10 eV and 0.06 eV). Including information from
future baryon acoustic oscillation measurements with the complete BOSS, Type 1a
supernovae distance moduli from WFIRST, and a realistic prior on the Hubble
constant, these upper limits shrink to 0.118 eV and 0.080 eV for the inverted
and normal hierarchies, respectively. Addition of these distance priors also
yields percent-level constraints on w. We find tension between our MCMC results
and the results of a Fisher matrix analysis, most likely due to a strong
geometric degeneracy between the total neutrino mass, the Hubble constant, and
w in the unlensed CMB power spectra. If the minimal-mass, normal hierarchy were
realised in nature, the inverted hierarchy should be disfavoured by the full
data combination at typically greater than the 2-sigma level. For the
minimal-mass inverted hierarchy, we compute the Bayes' factor between the two
hierarchies for various combinations of our forecast datasets, and find that
the future probes considered here should be able to provide `strong' evidence
(odds ratio 12:1) for the inverted hierarchy. Finally, we consider potential
biases of the other cosmological parameters from assuming the wrong hierarchy
and find that all biases on the parameters are below their 1-sigma marginalised
errors.Comment: 16 pages, 13 figures; minor changes to match the published version,
references adde
Analysis of SLX4/FANCP in non-BRCA1/2-mutated breast cancer families
<p>Abstract</p> <p>Background</p> <p>Genes that, when mutated, cause Fanconi anemia or greatly increase breast cancer risk encode for proteins that converge on a homology-directed DNA damage repair process. Mutations in the <it>SLX4 </it>gene, which encodes for a scaffold protein involved in the repair of interstrand cross-links, have recently been identified in unclassified Fanconi anemia patients. A mutation analysis of <it>SLX4 </it>in German or Byelorussian familial cases of breast cancer without detected mutations in <it>BRCA1 </it>or <it>BRCA2 </it>has been completed, with globally negative results.</p> <p>Methods</p> <p>The genomic region of <it>SLX4</it>, comprising all exons and exon-intron boundaries, was sequenced in 94 Spanish familial breast cancer cases that match a criterion indicating the potential presence of a highly-penetrant germline mutation, following exclusion of <it>BRCA1 </it>or <it>BRCA2 </it>mutations.</p> <p>Results</p> <p>This mutational analysis revealed extensive genetic variation of <it>SLX4</it>, with 21 novel single nucleotide variants; however, none could be linked to a clear alteration of the protein function. Nonetheless, genotyping 10 variants (nine novel, all missense amino acid changes) in a set of controls (138 women and 146 men) did not detect seven of them.</p> <p>Conclusions</p> <p>Overall, while the results of this study do not identify clearly pathogenic mutations of <it>SLX4 </it>contributing to breast cancer risk, further genetic analysis, combined with functional assays of the identified rare variants, may be warranted to conclusively assess the potential link with the disease.</p
The feasibility of a randomised controlled trial to compare the cost-effectiveness of palliative cardiology or usual care in people with advanced heart failure: Two exploratory prospective cohorts
© 2018, © The Author(s) 2018. Background: The effectiveness of cardiology-led palliative care is unknown; we have insufficient information to conduct a full trial. Aim: To assess the feasibility (recruitment/retention, data quality, variability/sample size estimation, safety) of a clinical trial of palliative cardiology effectiveness. Design: Non-randomised feasibility. Setting/participants: Unmatched symptomatic heart failure patients on optimal cardiac treatment from (1) cardiology-led palliative service (caring together group) and (2) heart failure liaison service (usual care group). Outcomes/safety: Symptoms (Edmonton Symptom Assessment Scale), Kansas City Cardiomyopathy Questionnaire, performance, understanding of disease, anticipatory care planning, cost-effectiveness, survival and carer burden. Results: A total of 77 participants (caring together group = 43; usual care group = 34) were enrolled (53% men; mean age 77 years (33–100)). The caring together group scored worse in Edmonton Symptom Assessment Scale (43.5 vs 35.2) and Kansas City Cardiomyopathy Questionnaire (35.4 vs 39.9). The caring together group had a lower consent/screen ratio (1:1.7 vs 1: 2.8) and few died before approach (0.08% vs 16%) or declined invitation (17% vs 37%). Data quality: At 4 months, 74% in the caring together group and 71% in the usual care group provided data. Most attrition was due to death or deterioration. Data quality in self-report measures was otherwise good. Safety: There was no difference in survival. Symptoms and quality of life improved in both groups. A future trial requires 141 (202 allowing 30% attrition) to detect a minimal clinical difference (1 point) in Edmonton Symptom Assessment Scale score for breathlessness (80% power). More participants (176; 252 allowing 30% attrition) are needed to detect a 10.5 change in Kansas City Cardiomyopathy Questionnaire score (80% power; minimum clinical difference = 5). Conclusion: A trial to test the clinical effectiveness (improvement in breathlessness) of cardiology-led palliative care is feasible
Expression of G protein-coupled receptors and related proteins in HEK293, AtT20, BV2, and N18 cell lines as revealed by microarray analysis
<p>Abstract</p> <p>Background</p> <p>G protein coupled receptors (GPCRs) are one of the most widely studied gene superfamilies. Thousands of GPCR research studies have utilized heterologous expression systems such as human embryonic kidney cells (HEK293). Though often treated as 'blank slates', these cell lines nevertheless endogenously express GPCRs and related signaling proteins. The outcome of a given GPCR study can be profoundly influenced by this largely unknown complement of receptors and/or signaling proteins. Little easily accessible information exists that describes the expression profiles of the GPCRs in cell lines. What is accessible is often limited in scope - of the hundreds of GPCRs and related proteins, one is unlikely to find information on expression of more than a dozen proteins in a given cell line. Microarray technology has allowed rapid analysis of mRNA levels of thousands of candidate genes, but though often publicly available, the results can be difficult to efficiently access or even to interpret.</p> <p>Results</p> <p>To bridge this gap, we have used microarrays to measure the mRNA levels of a comprehensive profile of non-chemosensory GPCRs and over a hundred GPCR signaling related gene products in four cell lines frequently used for GPCR research: HEK293, AtT20, BV2, and N18.</p> <p>Conclusions</p> <p>This study provides researchers an easily accessible mRNA profile of the endogenous signaling repertoire that these four cell lines possess. This will assist in choosing the most appropriate cell line for studying GPCRs and related signaling proteins. It also provides a better understanding of the potential interactions between GPCRs and those signaling proteins.</p
Significant benefits of AIP testing and clinical screening in familial isolated and young-onset pituitary tumors
Context
Germline mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene are responsible for a subset of familial isolated pituitary adenoma (FIPA) cases and sporadic pituitary neuroendocrine tumors (PitNETs).
Objective
To compare prospectively diagnosed AIP mutation-positive (AIPmut) PitNET patients with clinically presenting patients and to compare the clinical characteristics of AIPmut and AIPneg PitNET patients.
Design
12-year prospective, observational study.
Participants & Setting
We studied probands and family members of FIPA kindreds and sporadic patients with disease onset ≤18 years or macroadenomas with onset ≤30 years (n = 1477). This was a collaborative study conducted at referral centers for pituitary diseases.
Interventions & Outcome
AIP testing and clinical screening for pituitary disease. Comparison of characteristics of prospectively diagnosed (n = 22) vs clinically presenting AIPmut PitNET patients (n = 145), and AIPmut (n = 167) vs AIPneg PitNET patients (n = 1310).
Results
Prospectively diagnosed AIPmut PitNET patients had smaller lesions with less suprasellar extension or cavernous sinus invasion and required fewer treatments with fewer operations and no radiotherapy compared with clinically presenting cases; there were fewer cases with active disease and hypopituitarism at last follow-up. When comparing AIPmut and AIPneg cases, AIPmut patients were more often males, younger, more often had GH excess, pituitary apoplexy, suprasellar extension, and more patients required multimodal therapy, including radiotherapy. AIPmut patients (n = 136) with GH excess were taller than AIPneg counterparts (n = 650).
Conclusions
Prospectively diagnosed AIPmut patients show better outcomes than clinically presenting cases, demonstrating the benefits of genetic and clinical screening. AIP-related pituitary disease has a wide spectrum ranging from aggressively growing lesions to stable or indolent disease course
Recommended from our members
Registered replication report: a large multilab cross-cultural conceptual replication of Turri, Buckwalter, & Blouw (2015)
According to the Justified True Belief account of knowledge (JTB), a person can only truly know something if they have a belief that is both justified and true (i.e., knowledge is justified true belief). This account was challenged by Gettier (1963), who argued that JTB does not explain knowledge attributions in certain situations, later called Gettier-type cases, wherein a protagonist is justified in believing something to be true, but their belief was only correct due to luck. Lay people may not attribute knowledge to protagonists with justified but only luckily true beliefs. While some research has found evidence for these so-called Gettier intuitions (e.g., Machery et al., 2017a), Turri et al. (2015) found no evidence that participants attributed knowledge in a counterfeit-object Gettier-type case differently than in a matched case of justified true belief. In a large-scale, cross-cultural conceptual replication of Turri and colleagues’ (2015) Experiment 1 (N = 4,724) using a within-participants design and three vignettes across 19 geopolitical regions, we did find evidence for Gettier intuitions; participants were 1.86 times more likely to attribute knowledge to protagonists in standard cases of justified true belief than to protagonists in Gettier-type cases. These results suggest that Gettier intuitions may be detectable across different scenarios and cultural contexts. However, the size of the Gettier intuition effect did vary by vignette, and the Turri et al. (2015) vignette produced the smallest effect, which was similar in size to that observed in the original study. Differences across vignettes suggest epistemic intuitions may also depend on contextual factors unrelated to the criteria of knowledge, such as the characteristics of the protagonist being evaluated
- …