1,959 research outputs found
Incorporating Learning Analytics into Basic Course Administration: How to Embrace the Opportunity to Identify Inconsistencies and Inform Responses
Consistency is imperative to the success of a multi-section basic course. However, establishing consistent practices is a difficult task, especially when coupled with maintaining instructor autonomy. Learning analytics tools, designed to improve learning and teaching by collecting and analyzing pertinent information through interactive databases, can be used by basic course administrators to improve consistency. Using a reflective case study methodology we share our experience incorporating a learning analytics platform into our basic course. In doing so, we highlight the role this technology can play in terms of identifying areas of inconsistency as well as informing ways to improve overall course delivery. Three major areas of inconsistency were uncovered: (1) the use of online grade books; (2) utilization of course-wide rubrics; (3) and instances of grade inflation. Stemming from these findings is a set of very practical implications regarding the coupling of learning analytics and basic course administration. These include clarifying the two-step process of identifying inconsistencies and informing solutions as well as introducing the concept of collaborative consistency, the term we use to describe the co-construction of course materials (e.g., rubrics, schedules) and activities (e.g., norming). The case ultimately provides the opportunity for basic course directors to embrace the role of learning analytics technology
Strong Lensing Model of SPT-CLJ0356-5337, a Major Merger Candidate at Redshift 1.0359
We present an analysis of the mass distribution inferred from strong lensing
by SPT-CL J0356-5337, a cluster of galaxies at redshift z = 1.0359 revealed in
the follow-up of the SPT-SZ clusters. The cluster has an Einstein radius of
Erad=14 for a source at z = 3 and a mass within 500 kpc of M_500kpc =
4.0+-0.8x10^14Msol. Our spectroscopic identification of three multiply-imaged
systems (z = 2.363, z = 2.364, and z = 3.048), combined with HST F606W-band
imaging allows us to build a strong lensing model for this cluster with an rms
of <0.3'' between the predicted and measured positions of the multiple images.
Our modeling reveals a two-component mass distribution in the cluster. One mass
component is dominated by the brightest cluster galaxy and the other component,
separated by ~170 kpc, contains a group of eight red elliptical galaxies
confined in a ~9'' (~70 kpc) diameter circle. We estimate the mass ratio
between the two components to be between 1:1.25 and 1:1.58. In addition,
spectroscopic data reveal that these two near-equal mass cores have only a
small velocity difference of 300 km/s between the two components. This small
radial velocity difference suggests that most of the relative velocity takes
place in the plane of the sky, and implies that SPT-CL J0356-5337 is a major
merger with a small impact parameter seen face-on. We also assess the relative
contributions of galaxy-scale halos to the overall mass of the core of the
cluster and find that within 800 kpc from the brightest cluster galaxy about
27% of the total mass can be attributed to visible and dark matter associated
with galaxies, whereas only 73% of the total mass in the core comes from
cluster-scale dark matter halos.Comment: 19 pages, 11 figures. Submitted to Ap
Analysis Description Languages for the LHC
An analysis description language is a domain specific language capable of
describing the contents of an LHC analysis in a standard and unambiguous way,
independent of any computing framework. It is designed for use by anyone with
an interest in, and knowledge of, LHC physics, i.e., experimentalists,
phenomenologists and other enthusiasts. Adopting analysis description languages
would bring numerous benefits for the LHC experimental and phenomenological
communities ranging from analysis preservation beyond the lifetimes of
experiments or analysis software to facilitating the abstraction, design,
visualization, validation, combination, reproduction, interpretation and
overall communication of the analysis contents. Here, we introduce the analysis
description language concept and summarize the current efforts ongoing to
develop such languages and tools to use them in LHC analyses.Comment: Accepted contribution to the proceedings of The 8th Annual Conference
on Large Hadron Collider Physics, LHCP2020, 25-30 May, 2020, onlin
Reducing prolonged sedentary time using a treadmill desk acutely improves cardiometabolic risk markers in male and female adults
The objectives of this study were to evaluate the acute effects of interrupting prolonged sitting with an accumulated 2 h of light-intensity walking on postprandial cardiometabolic risk markers. In this randomised crossover trial, 24 participants (twelve males) aged 18-55 years took part in two, 6.5 h conditions: 1) prolonged sitting (SIT) and 2) sitting interrupted hourly with 20 min light-intensity treadmill desk walking at between 1.2-3.5 km/h-1 (INT-SIT). Standardized meals were provided at 0 h and 3 h. Blood samples and blood pressure measures were taken hourly. Statistical analyses were completed using linear mixed models. Postprandial incremental area under the curve responses (mmol/L∙6.5 h) for glucose (4.52 [3.47, 5.56] and 6.66 [5.62, 7.71] for INT-SIT and SIT, respectively) and triglycerides (1.96 [0.96, 2.96] and 2.71 [1.70, 3.71] mmol/L∙6.5 h, for INT-SIT and SIT, respectively) were significantly lower in INT-SIT than SIT. Mean systolic and diastolic blood pressure responses were lower by 3% and 4%, respectively, in INT-SIT than SIT (P0.05). These findings suggest that interrupting sitting with an accumulated 2 h of light-intensity walking acutely improves cardiometabolic risk levels in males and females compared with prolonged sitting
Host-linked soil viral ecology along a permafrost thaw gradient
Climate change threatens to release abundant carbon that is sequestered at high latitudes, but the constraints on microbial metabolisms that mediate the release of methane and carbon dioxide are poorly understood1,2,3,4,5,6,7. The role of viruses, which are known to affect microbial dynamics, metabolism and biogeochemistry in the oceans8,9,10, remains largely unexplored in soil. Here, we aimed to investigate how viruses influence microbial ecology and carbon metabolism in peatland soils along a permafrost thaw gradient in Sweden. We recovered 1,907 viral populations (genomes and large genome fragments) from 197 bulk soil and size-fractionated metagenomes, 58% of which were detected in metatranscriptomes and presumed to be active. In silico predictions linked 35% of the viruses to microbial host populations, highlighting likely viral predators of key carbon-cycling microorganisms, including methanogens and methanotrophs. Lineage-specific virus/host ratios varied, suggesting that viral infection dynamics may differentially impact microbial responses to a changing climate. Virus-encoded glycoside hydrolases, including an endomannanase with confirmed functional activity, indicated that viruses influence complex carbon degradation and that viral abundances were significant predictors of methane dynamics. These findings suggest that viruses may impact ecosystem function in climate-critical, terrestrial habitats and identify multiple potential viral contributions to soil carbon cycling
SPT-CL J2215−3537: A Massive Starburst at the Center of the Most Distant Relaxed Galaxy Cluster
We present the discovery of the most distant, dynamically relaxed cool core cluster, SPT-CL J2215−3537 (SPT2215), and its central brightest cluster galaxy (BCG) at z = 1.16. Using new X-ray observations, we demonstrate that SPT2215 harbors a strong cool core with a central cooling time of 200 Myr (at 10 kpc) and a maximal intracluster medium cooling rate of 1900 ± 400 M⊙ yr−1. This prodigious cooling may be responsible for fueling the extended, star-forming filaments observed in Hubble Space Telescope imaging. Based on new spectrophotometric data, we detect bright [O ii] emission in the BCG, implying an unobscured star formation rate (SFR) of M⊙ yr−1. The detection of a weak radio source (2.0 ± 0.8 mJy at 0.8 GHz) suggests ongoing feedback from an active galactic nucleus (AGN), though the implied jet power is less than half the cooling luminosity of the hot gas, consistent with cooling overpowering heating. The extreme cooling and SFR of SPT2215 are rare among known cool core clusters, and it is even more remarkable that we observe these at such high redshift, when most clusters are still dynamically disturbed. The high mass of this cluster, coupled with the fact that it is dynamically relaxed with a highly isolated BCG, suggests that it is an exceptionally rare system that must have formed very rapidly in the early universe. Combined with the high SFR, SPT2215 may be a high-z analog of the Phoenix cluster, potentially providing insight into the limits of AGN feedback and star formation in the most massive galaxies
A Gradual Decline of Star Formation since Cluster In-fall: New Kinematic Insights into Environmental Quenching at 0.3 1.1
The environments where galaxies reside crucially shape their star formation
histories. We investigate a large sample of 1626 cluster galaxies located
within 105 galaxy clusters spanning a large range in redshift (. The galaxy clusters are massive (MM), and are uniformly selected from the SPT and ACT
Sunyaev-Zel'dovich (SZ) surveys. With spectra in-hand for thousands of cluster
members, we use galaxies' position in projected phase space as a proxy for
their in-fall times, which provides a more robust measurement of environment
than quantities such as projected cluster-centric radius. We find clear
evidence for a gradual age increase of the galaxy's mean stellar populations
( 0.71 0.4 Gyr based on a 4000 break, )
with the time spent in the cluster environment. This environmental quenching
effect is found regardless of galaxy luminosity (faint or bright) and redshift
(low- or high-), although the exact stellar age of galaxies depends on
both parameters at fixed environmental effects. Such a systematic increase of
with in-fall proxy would suggest that galaxies that were
accreted into hosts earlier were quenched earlier, due to longer exposure to
environmental effects such as ram pressure stripping and starvation. Compared
to the typical dynamical time scales of Gyr of cluster galaxies, the
relatively small age increase ( 0.71 0.4 Gyr) found in our sample
galaxies seems to suggest that a slow environmental process such as starvation
is the dominant quenching pathway. Our results provide new insights into
environmental quenching effects spanning a large range in cosmic time ( Gyr, --1.13) and demonstrate the power of using a
kinematically-derived in-fall time proxy.Comment: 22 pages, 9 figures, 3 tables. Accepted for publication by Ap
Synthesizing Stellar Populations in South Pole Telescope Galaxy Clusters. I. Ages of Quiescent Member Galaxies at 0.3 < z < 1.4
Using stellar population synthesis models to infer star formation histories (SFHs), we analyze photometry and spectroscopy of a large sample of quiescent galaxies that are members of Sunyaev–Zel'dovich (SZ)-selected galaxy clusters across a wide range of redshifts. We calculate stellar masses and mass-weighted ages for 837 quiescent cluster members at 0.3 < z < 1.4 using rest-frame optical spectra and the Python-based Prospector framework, from 61 clusters in the SPT-GMOS Spectroscopic Survey (0.3 < z < 0.9) and three clusters in the SPT Hi-z cluster sample (1.25 < z < 1.4). We analyze spectra of subpopulations divided into bins of redshift, stellar mass, cluster mass, and velocity-radius phase-space location, as well as by creating composite spectra of quiescent member galaxies. We find that quiescent galaxies in our data set sample a diversity of SFHs, with a median formation redshift (corresponding to the lookback time from the redshift of observation to when a galaxy forms 50% of its mass, t50) of z = 2.8 ± 0.5, which is similar to or marginally higher than that of massive quiescent field and cluster galaxy studies. We also report median age–stellar mass relations for the full sample (age of the universe at t50 (Gyr) = 2.52 (±0.04)–1.66 (±0.12) log10(M/1011M⊙)) and recover downsizing trends across stellar mass; we find that massive galaxies in our cluster sample form on aggregate ∼0.75 Gyr earlier than lower-mass galaxies. We also find marginally steeper age–mass relations at high redshifts, and report a bigger difference in formation redshifts across stellar mass for fixed environment, relative to formation redshifts across environment for fixed stellar mass
Rapid feedback on hospital onset SARS-CoV-2 infections combining epidemiological and sequencing data.
BACKGROUND: Rapid identification and investigation of healthcare-associated infections (HCAIs) is important for suppression of SARS-CoV-2, but the infection source for hospital onset COVID-19 infections (HOCIs) cannot always be readily identified based only on epidemiological data. Viral sequencing data provides additional information regarding potential transmission clusters, but the low mutation rate of SARS-CoV-2 can make interpretation using standard phylogenetic methods difficult. METHODS: We developed a novel statistical method and sequence reporting tool (SRT) that combines epidemiological and sequence data in order to provide a rapid assessment of the probability of HCAI among HOCI cases (defined as first positive test >48 hr following admission) and to identify infections that could plausibly constitute outbreak events. The method is designed for prospective use, but was validated using retrospective datasets from hospitals in Glasgow and Sheffield collected February-May 2020. RESULTS: We analysed data from 326 HOCIs. Among HOCIs with time from admission ≥8 days, the SRT algorithm identified close sequence matches from the same ward for 160/244 (65.6%) and in the remainder 68/84 (81.0%) had at least one similar sequence elsewhere in the hospital, resulting in high estimated probabilities of within-ward and within-hospital transmission. For HOCIs with time from admission 3-7 days, the SRT probability of healthcare acquisition was >0.5 in 33/82 (40.2%). CONCLUSIONS: The methodology developed can provide rapid feedback on HOCIs that could be useful for infection prevention and control teams, and warrants further prospective evaluation. The integration of epidemiological and sequence data is important given the low mutation rate of SARS-CoV-2 and its variable incubation period. FUNDING: COG-UK HOCI funded by COG-UK consortium, supported by funding from UK Research and Innovation, National Institute of Health Research and Wellcome Sanger Institute.COG-UK HOCI funded by COG-UK consortium, supported by funding from UK Research and Innovation, National Institute of Health Research and Wellcome Sanger Institute
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