1,683 research outputs found
The 1.4 GHz Cosmic Star Formation History at z < 1.3
We measure the cosmic star formation history out to z = 1.3 using a sample of
918 radio-selected star forming galaxies within the 2 square degree COSMOS
field. To increase our sample size, we combine 1.4 GHz flux densities from the
VLA-COSMOS catalogue with flux densities measured from the VLA-COSMOS radio
continuum image at the positions of I < 26.5 galaxies, enabling us to detect
1.4 GHz sources as faint as 40 uJy. We find radio measurements of the cosmic
star formation history are highly dependent on sample completeness and models
used to extrapolate the faint end of the radio luminosity function. For our
preferred model of the luminosity function, we find the star formation rate
density increases from 0.019 Solar masses per year per cubic Mpc at z = 0.225
to 0.104 Solar masses per year per cubic Mpc, which agrees to within 33% of
recent UV, IR and 3 GHz measurements of the cosmic star formation history.Comment: 7 pages, 3 figures. Accepted for publication in Publications of the
Astronomical Society of Australi
Release of insulin granules by simultaneous, high-speed correlative SICM-FCM
Exocytosis of peptides and steroids stored in a dense core vesicular (DCV) form is the final step of every secretory pathway, indispensable for the function of nervous, endocrine and immune systems. The lack of live imaging techniques capable of direct, label‐free visualisation of DCV release makes many aspects of the exocytotic process inaccessible to investigation. We describe the application of correlative scanning ion conductance and fluorescence confocal microscopy (SICM‐FCM) to study the exocytosis of individual granules of insulin from the top, nonadherent, surface of pancreatic β‐cells. Using SICM‐FCM, we were first to directly follow the topographical changes associated with physiologically induced release of insulin DCVs. This allowed us to report the kinetics of the full fusion of the insulin vesicle as well as the subsequent solubilisation of the released insulin crystal
Effect of the velopharynx on intraluminal pressures in reconstructed pharynges derived from individuals with and without sleep apnea
The most collapsible part of the upper airway in the majority of individuals is the velopharynx which is the segment positioned behind the soft palate. As such it is an important morphological region for consideration in elucidating the pathogenesis of obstructive sleep apnea (OSA). This study compared steady flow properties during inspiration in the pharynges of nine male subjects with OSA and nine body-mass index (BMI)- and age-matched control male subjects without OSA. The k–ωωSST turbulence model was used to simulate the flow field in subject-specific pharyngeal geometric models reconstructed from anatomical optical coherence tomography (aOCT) data. While analysis of the geometry of reconstructed pharynges revealed narrowing at velopharyngeal level in subjects with OSA, it was not possible to clearly distinguish them from subjects without OSA on the basis of pharyngeal size and shape alone. By contrast, flow simulations demonstrated that pressure fields within the narrowed airway segments were sensitive to small differences in geometry and could lead to significantly different intraluminal pressure characteristics between subjects. The ratio between velopharyngeal and total pharyngeal pressure drops emerged as a relevant flow-based criterion by which subjects with OSA could be differentiated from those without
Esports: The chess of the 21st century
© 2019 Pluss, Bennett, Novak, Panchuk, Coutts and Fransen. For many decades, researchers have explored the true potential of human achievement. The expertise field has come a long way since the early works of de Groot (1965) and Chase and Simon (1973). Since then, this inquiry has expanded into the areas of music, science, technology, sport, academia, and art. Despite the vast amount of research to date, the capability of study methodologies to truly capture the nature of expertise remains questionable. Some considerations include (i) the individual bias in the retrospective recall of developmental activities, (ii) the ability to develop ecologically valid tasks, and (iii) difficulties capturing the influence of confounding factors on expertise. This article proposes that expertise research in electronic sports (esports) presents an opportunity to overcome some of these considerations. Esports involves individuals or teams of players that compete in video game competitions via human-computer interaction. Advantages of applying the expert performance approach in esports include (i) developmental activities are objectively tracked and automatically logged online, (ii) the constraints of representative tasks correspond with the real-world environment of esports performance, and (iii) expertise has emerged without the influence of guided systematic training environments. Therefore, this article argues that esports research provides an ideal opportunity to further advance research on the development and assessment of human expertise
Dynamical biomarkers in teams and other multiagent systems
Effective team behavior in high-performance environments such as in sport and the military requires individual team members to efficiently perceive the unfolding task events, predict the actions and action intents of the other team members, and plan and execute their own actions to simultaneously accomplish individual and collective goals. To enhance team performance through effective cooperation, it is crucial to measure the situation awareness and dynamics of each team member and how they collectively impact the team's functioning. Further, to be practically useful for real-life settings, such measures must be easily obtainable from existing sensors. This paper presents several methodologies that can be used on positional and movement acceleration data of team members to quantify and/or predict team performance, assess situation awareness, and to help identify task-relevant information to support individual decision-making. Given the limited reporting of these methods within military cohorts, these methodologies are described using examples from team sports and teams training in virtual environments, with discussion as to how they can be applied to real-world military teams.</p
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A versatile vacuum ultraviolet ion source for reduced pressure bipolar chemical ionization mass spectrometry
We present the development of a chemical ionization mass spectrometer ion source specifically designed for in situ measurements of trace gases in the upper troposphere and lower stratosphere. The ion source utilizes a commercially available photoionization krypton lamp, primarily emitting photons in the vacuum ultraviolet (VUV) region at wavelengths of 124 and 117 nm (corresponding to energies of 10 and 10.6 eV, respectively), coupled to a commercially available Vocus proton transfer reaction mass spectrometer. The VUV ion source can produce both negative and positive reagent ions; however, here we primarily focus on generating iodide anions (I−). The instrument's drift tube (also known as ion–molecule reactor) operates at pressures between 2 and 10 mbar, which facilitates ambient sampling at atmospheric pressures as low as 50 mbar. The low operating pressure reduces secondary ion chemistry that can occur in iodide chemical ionization mass spectrometry (CIMS). It also allows the addition of water vapor to the drift tube to exceed typical ambient humidity by more than 1 order of magnitude, significantly reducing ambient humidity dependence of sensitivities. An additional benefit of this ion source and drift tube is a 10- to 100-fold reduction in nitrogen consumed during operation relative to standard I− ion sources, resulting in significantly reduced instrument weight and operational costs. In iodide mode, sensitivities of 76 cps ppt−1 for nitric acid, 35 cps ppt−1 for Br2 and 8.9 cps ppt−1 for Cl2 were achieved. Lastly, we demonstrate that this ion source can generate benzene () and ammonium () reagent ions to expand the number of detected atmospheric trace gases.</p
De novo design of bioactive protein switches.
Allosteric regulation of protein function is widespread in biology, but is challenging for de novo protein design as it requires the explicit design of multiple states with comparable free energies. Here we explore the possibility of designing switchable protein systems de novo, through the modulation of competing inter- and intramolecular interactions. We design a static, five-helix 'cage' with a single interface that can interact either intramolecularly with a terminal 'latch' helix or intermolecularly with a peptide 'key'. Encoded on the latch are functional motifs for binding, degradation or nuclear export that function only when the key displaces the latch from the cage. We describe orthogonal cage-key systems that function in vitro, in yeast and in mammalian cells with up to 40-fold activation of function by key. The ability to design switchable protein functions that are controlled by induced conformational change is a milestone for de novo protein design, and opens up new avenues for synthetic biology and cell engineering
Misdiagnosing Melioidosis
Melioidosis is endemic in southern and Southeast Asia and northern Australia. Although relatively few indigenous cases are recognized in the Indian subcontinent, a substantial proportion of cases imported into the United Kingdom originate there, probably reflecting patterns of immigration and travel, and underdiagnosis within the Indian subcontinent
The ecology of palm genomes: repeat-associated genome size expansion is constrained by aridity
Genome size varies 2400-fold across plants, influencing their evolution through changes in cell size and cell division rates which impact plants' environmental stress tolerance. Repetitive element expansion explains much genome size diversity, and the processes structuring repeat "communities" are analogous to those structuring ecological communities. However, which environmental stressors influence repeat community dynamics has not yet been examined from an ecological perspective.
We measured genome size and leveraged climatic data for 91% of genera within the ecologically diverse palm family (Arecaceae). We then generated genomic repeat profiles for 141 palm species, and analysed repeats using phylogenetically informed linear models to explore relationships between repeat dynamics and environmental factors.
We show that palm genome size and repeat "community" composition are best explained by aridity. Specifically, Ty3-gypsy and TIR elements were more abundant in palm species from wetter environments, which generally had larger genomes, suggesting amplification. By contrast, Ty1-copia and LINE elements were more abundant in drier environments.
Our results suggest that water stress inhibits repeat expansion through selection on upper genome size limits. However, elements that may associate with stress-response genes (e.g. Ty1-copia) have amplified in arid-adapted palm species. Overall, we provide novel evidence of climate influencing the assembly of repeat "communities".JP was supported by a Ramón y Cajal Fellowship (RYC-2017-2274) funded by MCIN/AEI/10.13039/501100011033 and by ‘ESF Investing in your future’. SB was funded by a Garfield Weston Foundation postdoctoral fellowship. PN and JM were supported by the ELIXIR CZ Research Infrastructure Project (Czech Ministry of Education, Youth and Sports; grant no. LM2018131).IntroductionMaterials and Methods Plant material collection and genome size measurement Phylogenetic, environmental and genomic data collection Modelling relationships between genome size and environmental variables DNA repeat profiling Assessing repeat dynamics in palm genomesResults Palm genome size variation Aridity preferences of palm species help explain genome size variation Ecological metrics of palm repeat ‘communities’ vary with genome size Repeat abundances correlate with genome size Aridity preferences of palm species explain abundances of certain repeat lineagesDiscussion Palm genome size variation Aridity thresholds best explain palm genome size diversity The ‘community ecology’ of repeats correlates with genome size Repeat dynamics may be modulated by aridityConclusionsAcknowledgementsAuthor contributionsPeer reviewe
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