185 research outputs found
IllustrisTNG in the HSC-SSP: image data release and the major role of mini mergers as drivers of asymmetry and star formation
At fixed galaxy stellar mass, there is a clear observational connection
between structural asymmetry and offset from the star forming main sequence,
SFMS. Herein, we use the TNG50 simulation to investigate the relative
roles of major mergers (stellar mass ratios ), minor (), and mini mergers () in driving this
connection amongst star forming galaxies (SFGs). We use dust radiative transfer
post-processing with SKIRT to make a large, public collection of synthetic
Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) images of simulated TNG
galaxies over with (k images). Using their instantaneous SFRs,
known merger histories/forecasts, and HSC-SSP asymmetries, we show (1) that
TNG50 SFGs qualitatively reproduce the observed trend between SFMS and
asymmetry and (2) a strikingly similar trend emerges between SFMS and
the time-to-coalescence for mini mergers. Controlling for redshift, stellar
mass, environment, and gas fraction, we show that individual mini merger events
yield small enhancements in SFRs and asymmetries that are sustained on long
timescales (at least Gyr after coalescence, on average) -- in contrast
to major/minor merger remnants which peak at much greater amplitudes but are
consistent with controls only Gyr after coalescence. Integrating the
boosts in SFRs and asymmetries driven by mergers since in
TNG50 SFGs, we show that mini mergers are responsible for (i) per cent of
all merger-driven star formation and (ii) per cent of merger-driven
asymmetric structure. Due to their relative frequency and prolonged boost
timescales, mini mergers dominate over their minor and major counterparts in
driving star formation and asymmetry in SFGs.Comment: 32 pages; 18 figures; submitted to MNRAS; Image data available via
the TNG website: www.tng-project.org/bottrell2
Porosity estimation of (Moso bamboo) by computed tomography and backscattered electron imaging
This study aims to investigate and quantify the porosity in the cross section of Phyllostachys edulis (Moso bamboo) culm wall. The porosity results are expected to be utilised in numerical study of heat and moisture transfer. Computed tomography (CT) and backscattered electron (BSE) imaging methods are utilised in this study because these two methods allow measurements of the anisotropic features of bamboo specimens. The results of these two methods can be represented as the function of the real dimension rather than the pore size distribution of the specimen. The specimens are obtained from eight different locations along the Moso bamboo culms. Both internodes and nodes specimens are measured in this study. The average porosity, standard deviation (SD) and coefficient of variation (COV) are calculated for BSE and CT results. Pearson product-moment correlation coefficient (PPMCC) is also calculated in this study to analyse the correlation between the BSE results and CT results. Typical porosity results from 400 sampling points and 10 portions average porosity are analysed in this study. The CT scanning results show similar trend with BSE results. The correlation relationship between BSE and CT results approaches moderate correlation level to strong correlation level. The average porosity of internode specimens is from 43.9 to 58.8 % by BSE measurement and from 44.9 to 63.4 % by CT measurement. The average porosity of node specimens is from 37.4 to 56.6 % by BSE measurement and from 32.1 to 62.2 % by CT measurement
Porosity estimation of Phyllostachys edulis (Moso bamboo) by computed tomography and backscattered electron imaging
This study aims to investigate and quantify the porosity in the cross
section of Phyllostachys edulis (Moso bamboo) culm wall. The porosity results are
expected to be utilised in numerical study of heat and moisture transfer. Computed
tomography (CT) and backscattered electron (BSE) imaging methods are utilised in
this study because these two methods allow measurements of the anisotropic features
of bamboo specimens. The results of these two methods can be represented as
the function of the real dimension rather than the pore size distribution of the
specimen. The specimens are obtained from eight different locations along the
Moso bamboo culms. Both internodes and nodes specimens are measured in this
study. The average porosity, standard deviation (SD) and coefficient of variation
(COV) are calculated for BSE and CT results. Pearson product-moment correlation
coefficient (PPMCC) is also calculated in this study to analyse the correlation
between the BSE results and CT results. Typical porosity results from 400 sampling
points and 10 portions average porosity are analysed in this study. The CT scanning
results show similar trend with BSE results. The correlation relationship between
BSE and CT results approaches moderate correlation level to strong correlation
level. The average porosity of internode specimens is from 43.9 to 58.8 % by BSE
measurement and from 44.9 to 63.4 % by CT measurement. The average porosity of
node specimens is from 37.4 to 56.6 % by BSE measurement and from 32.1 to
62.2 % by CT measurement
TOETVA parathyroid autofluorescence detection: hANDY-i endoscopy attachment
BackgroundTreatment options for thyroid pathologies have expanded to include scarless and remote access methods such as the transoral endoscopic thyroidectomy vestibular approach (TOETVA). Currently, no standardized methods exist for locating parathyroid glands (PGs) in patients undergoing TOETVA, which can lead to parathyroid injury and subsequent hypocalcemia. This early feasibility study describes and evaluates the hANDY-i endoscopic attachment for detecting PGs in transoral thyroidectomy.MethodsWe used a prototype parathyroid autofluorescence imager (hANDY-i) that was mounted to a 10-mm 0-degree endoscope. The device delivers a split screen view of Red-green-blue (RGB) and near-infrared autofluorescence (NIRAF) which allows for simultaneous anatomical localization and fluorescence visualization of PGs during endoscopic thyroid dissection.ResultsOne cadaveric case and two patient cases were included in this study. The endoscopic hANDY-i imaging system successfully visualized PGs during all procedures.ConclusionThe ability to leverage parathyroid autofluorescence during TOETVA may lead to improved PG localization and preservation. Further human studies are needed to assess its effect on postoperative hypocalcemia and hypoparathyroidism
Modelling a response as a function of high frequency count data: the association between physical activity and fat mass
We present a new statistical modelling approach where the response is a
function of high frequency count data. Our application is about investigating
the relationship between the health outcome fat mass and physical activity (PA)
measured by accelerometer. The accelerometer quantifies the intensity of
physical activity as counts per epoch over a given period of time. We use data
from the Avon longitudinal study of parents and children (ALSPAC) where
accelerometer data is available as a time series of accelerometer counts per
minute over seven days for a subset of children. In order to compare
accelerometer profiles between individuals and to reduce the high dimension a
functional summary of the profiles is used. We use the histogram as a
functional summary due to its simplicity, suitability and ease of
interpretation. Our model is an extension of generalised regression of scalars
on functions or signal regression. It allows also multi-dimensional functional
predictors and additive non-linear predictors for metric covariates. The
additive multidimensional functional predictors allow investigating specific
questions about whether the effect of PA varies over its intensity, by gender,
by time of day or by day of the week. The key feature of the model is that it
utilises the full profile of measured PA without requiring cut-points defining
intensity levels for light, moderate and vigorous activity. We show that the
(not necessarily causal) effect of PA is not linear and not constant over the
activity intensity. Also, there is little evidence to suggest that the effect
of PA intensity varies by gender or whether it happens on weekdays or on
weekends
Does home neighbourhood supportiveness influence the location more than volume of adolescent's physical activity? An observational study using Global Positioning Systems
Background: Environmental characteristics of home neighbourhoods are hypothesised to be associated with residents’ physical activity levels, yet many studies report only weak or equivocal associations. We theorise that this may be because neighbourhood characteristics influence the location of activity more than the volume. Using a sample of UK adolescents, we examine the role of home neighbourhood supportiveness for physical activity, both in terms of volume of activity undertaken and a measure of proximity to home at which activity takes place. Methods: Data were analysed from 967 adolescents living in and around the city of Bristol, UK. Each participant wore an accelerometer and a GPS device for seven days during school term time. These data were integrated into a Geographical Information System containing information on the participants’ home neighbourhoods and measures of environmental supportiveness. We then identified the amount of out-of-school activity of different intensities that adolescents undertook inside their home neighbourhood and examined how this related to home neighbourhood supportiveness. Results: We found that living in a less supportive neighbourhood did not negatively impact the volume of physical activity that adolescents undertook. Indeed these participants recorded similar amounts of activity (e.g. 20.5 mins per day of moderate activity at weekends) as those in more supportive neighbourhoods (18.6 mins per day). However, the amount of activity adolescents undertook inside their home neighbourhood did differ according to supportiveness; those living in less supportive locations had lower odds of recording activity inside their home neighbourhood. This was observed across all intensities of activity including sedentary, light, moderate, and vigorous. Conclusions: Our findings suggest that the supportiveness of the neighbourhood around home may have a greater influence on the location of physical activity than the volume undertaken. This finding is at odds with the premise of the socio-ecological models of physical activity that have driven this research field for the last two decades, and has implications for future research, as by simply measuring volumes of activity we may be underestimating the impact of the environment on physical activity behaviours
BeadArray Expression Analysis Using Bioconductor
Illumina whole-genome expression BeadArrays are a popular choice in gene profiling studies. Aside from the vendor-provided software tools for analyzing BeadArray expression data (GenomeStudio/BeadStudio), there exists a comprehensive set of open-source analysis tools in the Bioconductor project, many of which have been tailored to exploit the unique properties of this platform. In this article, we explore a number of these software packages and demonstrate how to perform a complete analysis of BeadArray data in various formats. The key steps of importing data, performing quality assessments, preprocessing, and annotation in the common setting of assessing differential expression in designed experiments will be covered
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