Processing time not modality dominates shift costs in the modality-shifting effect

Shifting attention between visual and auditory targets is associated with reaction time costs, known as the modality-shifting effect. The type of modality shifted from, e.g., auditory or visual is suggested to have an effect on the degree of cost. Studies report greater costs shifting from visual stimuli, yet notably used visual stimuli that are also identified slower than the auditory. It is not clear whether the cost is specific to modality effects, or with identification speed independent of modality. Here, to interpret whether the effects are due to modality or identification time, switch costs are instead compared with auditory stimuli that are identified slower than the visual (inverse of tested previously). A second condition used the same auditory stimuli at a low intensity, allowing comparison of semantically identical stimuli that are even slower to process. The current findings contradicted suggestions of a general difficulty in shifting from visual stimuli (as previously reported), and instead suggest that cost is reduced when targets are preceded by a more rapidly processed stimulus. ‘Modality-Shifting’ as it is often termed induces shifting costs, but the costs are not because of a change of modality per se, but because of a change in identification speed, where the degree of cost is dependent on the processing time of the surrounding stimuli

The colonoscopist's guide to the vocabulary of colorectal neoplasia: histology, morphology, and management

Prevention of colorectal cancer by colonoscopy requires effective and safe insertion technique, high level detection of precancerous lesions, and skillful use of curative endoscopic resection techniques. Lesion detection, characterization, use of appropriate resection methods, prediction of cancer at colonoscopy, and management of malignant polyps, all depend on an accurate and complete understanding of an extensive vocabulary describing the histology and morphology of neoplastic colorectal lesions. Incomplete understanding of vocabulary terms can lead to management errors. We provide a colonoscopist’s perspective on the vocabulary of colorectal neoplasia, and discuss the interaction of specific terms with management decisions

Abundant cyanopolyynes as a probe of infall in the Serpens South cluster-forming region

We have detected bright HC7N J = 21-20 emission toward multiple locations in the Serpens South cluster-forming region using the K-Band Focal Plane Array at the Robert C. Byrd Green Bank Telescope. HC7N is seen primarily toward cold filamentary structures that have yet to form stars, largely avoiding the dense gas associated with small protostellar groups and the main central cluster of Serpens South. Where detected, the HC7N abundances are similar to those found in other nearby star forming regions. Toward some HC7N `clumps', we find consistent variations in the line centroids relative to NH3 (1,1) emission, as well as systematic increases in the HC7N non-thermal line widths, which we argue reveal infall motions onto dense filaments within Serpens South with minimum mass accretion rates of M ~ 2-5 M_sun Myr^-1. The relative abundance of NH3 to HC7N suggests that the HC7N is tracing gas that has been at densities n ~ 10^4 cm^-3, for timescales t < 1-2 x 10^5 yr. Since HC7N emission peaks are rarely co-located with those of either NH3 or continuum, it is likely that Serpens South is not particularly remarkable in its abundance of HC7N, but instead the serendipitous mapping of HC7N simultaneously with NH3 has allowed us to detect HC7N at low abundances in regions where it otherwise may not have been looked for. This result extends the known star-forming regions containing significant HC7N emission from typically quiescent regions, like the Taurus molecular cloud, to more complex, active environments.Comment: 19 pages, 13 figures, accepted to MNRAS. Version with full resolution figures available at http://www.dunlap.utoronto.ca/~friesen/Friesen_HC7N.pd

Dune formation on the present Mars

We apply a model for sand dunes to calculate formation of dunes on Mars under the present Martian atmospheric conditions. We find that different dune shapes as those imaged by Mars Global Surveyor could have been formed by the action of sand-moving winds occuring on today's Mars. Our calculations show, however, that Martian dunes could be only formed due to the higher efficiency of Martian winds in carrying grains into saltation. The model equations are solved to study saltation transport under different atmospheric conditions valid for Mars. We obtain an estimate for the wind speed and migration velocity of barchan dunes at different places on Mars. From comparison with the shape of bimodal sand dunes, we find an estimate for the timescale of the changes in Martian wind regimes.Comment: 16 pages, 12 figure

The Mariner 5 flight path and its determination from tracking data

Mariner 5 flight path and its determination from tracking dat

Dynamical structure of the inner 100 AU of the deeply embedded protostar IRAS 16293-2422

A fundamental question about the early evolution of low-mass protostars is when circumstellar disks may form. High angular resolution observations of molecular transitions in the (sub)millimeter wavelength windows make it possible to investigate the kinematics of the gas around newly-formed stars, for example to identify the presence of rotation and infall. IRAS 16293-2422 was observed with the extended Submillimeter Array (eSMA) resulting in subarcsecond resolution (0.46" x 0.29", i.e. $\sim$ 55 $\times$ 35~AU) images of compact emission from the C$^{17}$O (3-2) and C$^{34}$S (7-6) transitions at 337~GHz (0.89~mm). To recover the more extended emission we have combined the eSMA data with SMA observations of the same molecules. The emission of C$^{17}$O (3-2) and C$^{34}$S (7-6) both show a velocity gradient oriented along a northeast-southwest direction with respect to the continuum marking the location of one of the components of the binary, IRAS16293A. Our combined eSMA and SMA observations show that the velocity field on the 50--400~AU scales is consistent with a rotating structure. It cannot be explained by simple Keplerian rotation around a single point mass but rather needs to take into account the enclosed envelope mass at the radii where the observed lines are excited. We suggest that IRAS 16293-2422 could be among the best candidates to observe a pseudo-disk with future high angular resolution observations.Comment: Accepted for publication in ApJ, 18 pages, 10 figure

Using a Web-Archiving Service - How to ensure your cited web-references remain available and valid

In today’s electronic information age, academic authors increasingly cite online resources such as blog posts, news articles, online policies and reports in their scholarly publications. Citing such webpages, or their URLs, poses long-term accessibility concern due to the ephemeral nature of the Internet: webpages can (and do!) change or disappear1 over time. When looking up cited web references, readers of scholarly publications might thus find content that is different from what author/s originally referenced; this is referred to as ‘content drift’. Other times, readers are faced with a ‘404 Page Not Found’ message, a phenomenon known as ‘link rot’2. A recent Canadian study3 for example found a 23% link rot when examining 11,437 links in 664 doctoral dissertations from 2011-2015. Older publications are likely to face even higher rates of invalid links. Luckily, there are a few things you can do to make your cited web references more stable. The most common method is to use a web archiving service. Using a web archiving service means your web references and links are more likely to connect the reader to the content accessed at the time of writing/citing. In other words, references are less likely to “rot” or “drift” over time. As citing authors, we have limited influence on preserving web content that we don’t own. We are generally at the mercy of the information custodians who tend to adjust, move or delete their web content to keep their site(s) current and interesting. All we can do to keep web content that we don’t own but want to cite intact so that our readers can still access it in years to come is to create a “representative memento" of the online material as it was at the time of citing. This can be achieved by submitting the URL of the webpage we want to cite to a web archiving service which will generate a static (‘cached’) copy of it and allocate it a new, unique and permanent link, also called ‘persistent identifier’. We can then use this new link to the archived webpage rather than the ephemeral link to the original webpage for our citation purposes. There are a range of web archives available. This guide contains a list of trusted web archiving services

Saltation transport on Mars

We present the first calculation of saltation transport and dune formation on Mars and compare it to real dunes. We find that the rate at which grains are entrained into saltation on Mars is one order of magnitude higher than on Earth. With this fundamental novel ingredient, we reproduce the size and different shapes of Mars dunes, and give an estimate for the wind velocity on Mars.Comment: 4 pages, 3 figure

Protostellar accretion traced with chemistry. High resolution C18O and continuum observations towards deeply embedded protostars in Perseus

Context: Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims: To characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods: A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program "Mass Assembly of Stellar Systems and their Evolution with the SMA" (MASSES). The size of the C$^{18}$O emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether a link can be established between accretion bursts and massive circumstellar disks. Results: Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C$^{18}$O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C$^{18}$O emission, we estimate an average interval between bursts of 20000-50000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.Comment: Accepted for publication in A&A, 21 pages, 13 figure