1,366 research outputs found
Academic Women Co-designing Education Futures in a Postdigital World
This paper draws on the collective knowledge-building of nine women from diverse disciplines, roles, cultures, and institutions in Australasian women in leadership programme. Brought together during Covid-19 through a shared interest and purpose concerning current and future developments in digital education, we offer knowledge and insight from our perspective as women leaders in academia, on co-designing futures in a postdigital world. Drawing on a duoethnographic research design, we reflected on our experiences as academic leaders and practitioners to systematically explore people, situations, and contexts through co-construction and dialogue. Our joint exploration uncovered themes of visibility, gravitas, and relationships. We provide evidence of the role co-design plays in our own practices, in our classrooms, and how our research design was strengthened through co-design. Finally, we offer an evolving model of co-design for leadership in higher education with communities of practice at its core
A small step toward generalizability: training a machine learning scoring function for structure-based virtual screening
Over the past few years, many machine learning-based scoring functions for predicting the binding of small molecules to proteins have been developed. Their objective is to approximate the distribution which takes two molecules as input and outputs the energy of their interaction. Only a scoring function that accounts for the interatomic interactions involved in binding can accurately predict binding affinity on unseen molecules. However, many scoring functions make predictions based on data set biases rather than an understanding of the physics of binding. These scoring functions perform well when tested on similar targets to those in the training set but fail to generalize to dissimilar targets. To test what a machine learning-based scoring function has learned, input attribution, a technique for learning which features are important to a model when making a prediction on a particular data point, can be applied. If a model successfully learns something beyond data set biases, attribution should give insight into the important binding interactions that are taking place. We built a machine learning-based scoring function that aimed to avoid the influence of bias via thorough train and test data set filtering and show that it achieves comparable performance on the Comparative Assessment of Scoring Functions, 2016 (CASF-2016) benchmark to other leading methods. We then use the CASF-2016 test set to perform attribution and find that the bonds identified as important by PointVS, unlike those extracted from other scoring functions, have a high correlation with those found by a distance-based interaction profiler. We then show that attribution can be used to extract important binding pharmacophores from a given protein target when supplied with a number of bound structures. We use this information to perform fragment elaboration and see improvements in docking scores compared to using structural information from a traditional, data-based approach. This not only provides definitive proof that the scoring function has learned to identify some important binding interactions but also constitutes the first deep learning-based method for extracting structural information from a target for molecule design
Quantitative characterization of hemodynamic properties and vasculature dysfunction of high-grade gliomas
Aberrations in tumor and peritumoral vasculature may not be distinguishable by cerebral blood flow (CBF) or cerebral blood volume (CBV) alone. The relationships between CBF and CBV were examined to estimate vasculature-specific hemodynamic characteristics. Twenty glioma patients were studied with dynamic susceptibility T 2 *-weighted MRI [(dynamic contrast-enhanced magnetic resonance imaging (DSC-MRI)] before and during week 1 and 3 of radiotherapy (RT). CBF and CBV were calculated from DSC-MRI, and relationships between the two were evaluated: the physiological measure of mean transit time (MTT) = CBV/CBF; empirical fitting using the power law CBV = constant × (CBF) Β . Three different tissue types were assessed: the Gd-enhancing tumor volume (GEV); non-enhanced abnormal tissue located beyond GEV but within the abnormal hyperintense region on FLAIR images (NEV); normal tissue in the hemisphere contralateral to the tumor (CNT). The effects of tissue types, CBV magnitudes (low, medium and high), before and during RT, on MTT and Β were analyzed by analysis of variance (ANOVA). The MTT and Β for the three tissue types were significantly different ( p < 0.009). MTT increased from CNT (1.60 s) to NEV (1.93 s) to GEV (2.28 s) ( p < 0.0005). Β was significantly greater in GEV (1.079) and NEV (1.070) than in CNT (1.025). Β increased with increasing CBV magnitude while MTT was independent of CBV magnitude. There was a significant decrease in MTT of NEV and GEV during week 3 of RT compared with pre-RT values for all CBV magnitudes. There was a significant increase in Β during RT in the tumor and peritumor. Progressive abnormalities in vasculature and hemodynamic characteristics of the vascular bed were delineated, with significant disorder in the tumor but mild abnormality in peritumoral tissue. Copyright © 2007 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56144/1/1118_ftp.pd
Revisiting Date and Party Hubs: Novel Approaches to Role Assignment in Protein Interaction Networks
The idea of 'date' and 'party' hubs has been influential in the study of
protein-protein interaction networks. Date hubs display low co-expression with
their partners, whilst party hubs have high co-expression. It was proposed that
party hubs are local coordinators whereas date hubs are global connectors. Here
we show that the reported importance of date hubs to network connectivity can
in fact be attributed to a tiny subset of them. Crucially, these few, extremely
central, hubs do not display particularly low expression correlation,
undermining the idea of a link between this quantity and hub function. The
date/party distinction was originally motivated by an approximately bimodal
distribution of hub co-expression; we show that this feature is not always
robust to methodological changes. Additionally, topological properties of hubs
do not in general correlate with co-expression. Thus, we suggest that a
date/party dichotomy is not meaningful and it might be more useful to conceive
of roles for protein-protein interactions rather than individual proteins. We
find significant correlations between interaction centrality and the functional
similarity of the interacting proteins.Comment: 27 pages, 5 main figures, 4 supplementary figure
Strong biases in infrared-selected gravitational lenses
Bright submm-selected galaxies have been found to be a rich source of strong
gravitational lenses. However, strong gravitational lensing of extended sources
leads inevitably to differential magnification. In this paper I quantify the
effect of differential magnification on simulated far-infrared and submm
surveys of strong gravitational lenses, using a foreground population of
Navarro-Frenk-White plus de Vaucouleurs' density profiles, with a model source
resembling the Cosmic Eyelash and QSO J1148+5251. Some emission line
diagnostics are surprisingly unaffected by differential magnification effects:
for example, the bolometric fractions of [C II] 158um and CO(J=1-0), often used
to infer densities and ionisation parameters, have typical differential
magnification effects that are smaller than the measurement errors. However,
the CO ladder itself is significantly affected. Far-infrared lensed galaxy
surveys (e.g. at 60um) strongly select for high-redshift galaxies with caustics
close to AGN, boosting the apparent bolometric contribution of AGN. The lens
configuration of IRAS F10214+4724 is naturally explained in this context.
Conversely, submm/mm-wave surveys (e.g. 500-1400um) strongly select for
caustics close to knots of star formation boosting the latter's bolometric
fraction. In general, estimates of bolometric fractions from spectral energy
distributions of strongly lensed infrared galaxies are so unreliable as to be
useless, unless a lens mass model is available to correct for differential
magnification.Comment: Note added in proof citing Hezaveh et al. (arXiv:1203.3267); other
minor changes made to match page proofs. MNRAS in press. 14 pages, 13
figures. Figures slightly degraded from publication version for smaller file
sizes and reliable printin
Quasars: the characteristic spectrum and the induced radiative heating
Using information on the cosmic X-ray background and the cumulative light of
active galactic nuclei at infrared wavelengths, the estimated local mass
density of galactic massive black holes (MBHs) and published AGN composite
spectra in the optical, UV and X-ray, we compute the characteristic
angular-integrated, broad-band spectral energy distribution of the average
quasar in the universe. We demonstrate that the radiation from such sources can
photoionize and Compton heat the plasma surrounding them up to an equilibrium
Compton temperature (Tc) of 2x10^7 K. It is shown that circumnuclear
obscuration cannot significantly affect the net gas Compton heating and cooling
rates, so that the above Tc value is approximately characteristic of both
obscured and unobscured quasars. This temperature is above typical gas
temperatures in elliptical galaxies and just above the virial temperatures of
giant ellipticals. The general results of this work can be used for accurate
calculations of the feedback effect of MBHs on both their immediate environs
and the more distant interstellar medium of their host galaxies.Comment: 15 pages, 5 figures. Revised version accepted for publication in
MNRA
Socio-Economic Instability and the Scaling of Energy Use with Population Size
The size of the human population is relevant to the development of a sustainable world, yet the forces setting growth or declines in the human population are poorly understood. Generally, population growth rates depend on whether new individuals compete for the same energy (leading to Malthusian or density-dependent growth) or help to generate new energy (leading to exponential and super-exponential growth). It has been hypothesized that exponential and super-exponential growth in humans has resulted from carrying capacity, which is in part determined by energy availability, keeping pace with or exceeding the rate of population growth. We evaluated the relationship between energy use and population size for countries with long records of both and the world as a whole to assess whether energy yields are consistent with the idea of an increasing carrying capacity. We find that on average energy use has indeed kept pace with population size over long time periods. We also show, however, that the energy-population scaling exponent plummets during, and its temporal variability increases preceding, periods of social, political, technological, and environmental change. We suggest that efforts to increase the reliability of future energy yields may be essential for stabilizing both population growth and the global socio-economic system
pUL21 is a viral phosphatase adaptor that promotes herpes simplex virus replication and spread.
The herpes simplex virus (HSV)-1 protein pUL21 is essential for efficient virus replication and dissemination. While pUL21 has been shown to promote multiple steps of virus assembly and spread, the molecular basis of its function remained unclear. Here we identify that pUL21 is a virus-encoded adaptor of protein phosphatase 1 (PP1). pUL21 directs the dephosphorylation of cellular and virus proteins, including components of the viral nuclear egress complex, and we define a conserved non-canonical linear motif in pUL21 that is essential for PP1 recruitment. In vitro evolution experiments reveal that pUL21 antagonises the activity of the virus-encoded kinase pUS3, with growth and spread of pUL21 PP1-binding mutant viruses being restored in adapted strains where pUS3 activity is disrupted. This study shows that virus-directed phosphatase activity is essential for efficient herpesvirus assembly and spread, highlighting the fine balance between kinase and phosphatase activity required for optimal virus replication.Wellcome Trust Senior Research Fellowship (219447/Z/19/Z),
Wellcome Trust Senior Research Fellowship (106207/Z/14/Z), Biotechnology and Biological Sciences Research Council Research Grant (BB/M021424/1),
Sir Henry Dale Fellowship, jointly funded by the Wellcome Trust and the Royal Society (098406/Z/12/B)
Biological variation in Anopheles darlingi root
Behavioural variation in the South American malaria vector Anopheles darlingi is described. At the centre of its distribution, in forest areas close to the city of Manaus, Brazil, it is primarily exophagic and exophilic. Mosquitoes from this area are chromosomally diverse. Towards the northern edge of its distribution (in Guyana and Venezuela) it is more endophagic and less diverse chromosomally. Similarly in the south (in the state of Minas Gerais) it is less polymorphic. In this area, however, it is primarily zoophilic and exophagic. Evidence is presented that female wing size may vary between populations. The possibility that this widely distributed species may be a complex could have important implications for future malaria control schemes
A Road Map for the Exploration of Neighboring Planetary Systems (ExNPS)
A brown dwarf star having only 20-50 times the mass of Jupiter is located below and to the left of the bright star GL 229 in this image from the Hubble Space Telescope. At the 19 light year distance to GL 229, the 7.7-arcsec separation between the star and the brown dwarf corresponds to roughly the separation between Pluto and the Sun in our Solar System. The goal of the program described in this report is to detect and characterize Earth-like planets around nearby stars where conditions suitable for life might be found. For a star like the Sun located 30 light years away, the appropriate star-planet separation would be almost 100 times closer than seen here for GL 229B
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