2,201 research outputs found
Prosodic phonological representations early in visual word recognition.
Two experiments examined the nature of the phonological representations used during visual word recognition. We tested whether a minimality constraint (R. Frost, 1998) limits the complexity of early representations to a simple string of phonemes. Alternatively, readers might activate elaborated representations that include prosodic syllable information before lexical access. In a modified lexical decision task (Experiment 1), words were preceded by parafoveal previews that were congruent with a target's initial syllable as well as previews that contained 1 letter more or less than the initial syllable. Lexical decision times were faster in the syllable congruent conditions than in the incongruent conditions. In Experiment 2, we recorded brain electrical potentials (electroencephalograms) during single word reading in a masked priming paradigm. The event-related potential waveform elicited in the syllable congruent condition was more positive 250-350 ms posttarget compared with the waveform elicited in the syllable incongruent condition. In combination, these experiments demonstrate that readers process prosodic syllable information early in visual word recognition in English. They offer further evidence that skilled readers routinely activate elaborated, speechlike phonological representations during silent reading. (PsycINFO Database Record (c) 2016 APA, all rights reserved
Early Integrators and the Passive Majority: An evaluation study of a large web-based bibliographic reference database
An evaluation is reported of user responses to zetoc, a service that provides access to the British Library electronic table of contents database and an email alerting service. Two questionnaire surveys and an interview programme gave data on over 800 users. The results show that about 17% are active users who are achieving a personal information management routine by integrating zetoc with other services (the early integrators). The other 83%, the `passive majority', make limited use of zetoc and do not achieve integration with other services. The interviews reveal that some of this group have a stable but restricted usage routine that limits information overload. The usage by others is less controlled and they make little use of the information they receive. The paper examines the impact of enhancements to the zetoc service to support integration and it discusses the barriers that prevent many users exploiting the potential of services available to them
Microcantilever Q Control Via Capacitive Coupling
We introduce a versatile method to control the quality factor Q of a conducting cantilever in an atomic force microscope (AFM) via capacitive coupling to the local environment. Using this method, Q may be reversibly tuned to within ~ 10% of any desired value over several orders of magnitude. A point-mass oscillator model describes the measured effect. Our simple Q control module increases the AFM functionality by allowing greater control of parameters such as scan speed and force gradient sensitivity, which we demonstrate by topographic imaging of a VO thin film in high vacuum.Physic
Weighing the Milky Way
We describe an experiment to measure the mass of the Milky Way galaxy. The
experiment is based on calculated light travel times along orthogonal
directions in the Schwarzschild metric of the Galactic center. We show that the
difference is proportional to the Galactic mass. We apply the result to light
travel times in a 10cm Michelson type interferometer located on Earth. The mass
of the Galactic center is shown to contribute 10^-6 to the flat space component
of the metric. An experiment is proposed to measure the effect.Comment: 10 pages, 1 figur
Listening to limericks: a pupillometry investigation of perceivers’ expectancy
What features of a poem make it captivating, and which cognitive mechanisms are sensitive to these features? We addressed these questions experimentally by measuring pupillary responses of 40 participants who listened to a series of Limericks. The Limericks ended with either a semantic, syntactic, rhyme or metric violation. Compared to a control condition without violations, only the rhyme violation condition induced a reliable pupillary response. An anomaly-rating study on the same stimuli showed that all violations were reliably detectable relative to the control condition, but the anomaly induced by rhyme violations was perceived as most severe. Together, our data suggest that rhyme violations in Limericks may induce an emotional response beyond mere anomaly detection
Renal Association Clinical Practice Guideline on Haemodialysis
© The Author(s) 2019. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.This guideline is written primarily for doctors and nurses working in dialysis units and related areas of medicine in the UK, and is an update of a previous version written in 2009. It aims to provide guidance on how to look after patients and how to run dialysis units, and provides standards which units should in general aim to achieve. We would not advise patients to interpret the guideline as a rulebook, but perhaps to answer the question: "what does good quality haemodialysis look like?"The guideline is split into sections: each begins with a few statements which are graded by strength (1 is a firm recommendation, 2 is more like a sensible suggestion), and the type of research available to back up the statement, ranging from A (good quality trials so we are pretty sure this is right) to D (more like the opinion of experts than known for sure). After the statements there is a short summary explaining why we think this, often including a discussion of some of the most helpful research. There is then a list of the most important medical articles so that you can read further if you want to - most of this is freely available online, at least in summary form.A few notes on the individual sections: 1. This section is about how much dialysis a patient should have. The effectiveness of dialysis varies between patients because of differences in body size and age etc., so different people need different amounts, and this section gives guidance on what defines "enough" dialysis and how to make sure each person is getting that. Quite a bit of this section is very technical, for example, the term "eKt/V" is often used: this is a calculation based on blood tests before and after dialysis, which measures the effectiveness of a single dialysis session in a particular patient. 2. This section deals with "non-standard" dialysis, which basically means anything other than 3 times per week. For example, a few people need 4 or more sessions per week to keep healthy, and some people are fine with only 2 sessions per week - this is usually people who are older, or those who have only just started dialysis. Special considerations for children and pregnant patients are also covered here. 3. This section deals with membranes (the type of "filter" used in the dialysis machine) and "HDF" (haemodiafiltration) which is a more complex kind of dialysis which some doctors think is better. Studies are still being done, but at the moment we think it's as good as but not better than regular dialysis. 4. This section deals with fluid removal during dialysis sessions: how to remove enough fluid without causing cramps and low blood pressure. Amongst other recommendations we advise close collaboration with patients over this. 5. This section deals with dialysate, which is the fluid used to "pull" toxins out of the blood (it is sometimes called the "bath"). The level of things like potassium in the dialysate is important, otherwise too much or too little may be removed. There is a section on dialysate buffer (bicarbonate) and also a section on phosphate, which occasionally needs to be added into the dialysate. 6. This section is about anticoagulation (blood thinning) which is needed to stop the circuit from clotting, but sometimes causes side effects. 7. This section is about certain safety aspects of dialysis, not seeking to replace well-established local protocols, but focussing on just a few where we thought some national-level guidance would be useful. 8. This section draws together a few aspects of dialysis which don't easily fit elsewhere, and which impact on how dialysis feels to patients, rather than the medical outcome, though of course these are linked. This is where home haemodialysis and exercise are covered. There is an appendix at the end which covers a few aspects in more detail, especially the mathematical ideas. Several aspects of dialysis are not included in this guideline since they are covered elsewhere, often because they are aspects which affect non-dialysis patients too. This includes: anaemia, calcium and bone health, high blood pressure, nutrition, infection control, vascular access, transplant planning, and when dialysis should be started.Peer reviewe
The Mid-IR and X-ray Selected QSO Luminosity Function
We present the J-band luminosity function of 1838 mid-infrared and X-ray
selected AGNs in the redshift range 0<z<5.85. These luminosity functions are
constructed by combining the deep multi-wavelength broad-band observations from
the UV to the mid-IR of the NDWFS Bootes field with the X-ray observations of
the XBootes survey and the spectroscopic observations of the same field by
AGES. Our sample is primarily composed of IRAC-selected AGNs, targeted using
modifications of the Stern et al.(2005) criteria, complemented by MIPS 24
microns and X-ray selected AGNs to alleviate the biases of IRAC mid-IR
selection against z~4.5 quasars and AGNs faint with respect to their hosts.
This sample provides an accurate link between low and high redshift AGN
luminosity functions and does not suffer from the usual incompleteness of
optical samples at z~3. We find that the space density of the brightest quasars
strongly decreases from z=3 to z=0, while the space density of faint quasars is
at least flat, and possibly increasing, over the same redshift range. At z>3 we
observe a decrease in the space density of quasars of all brightnesses. We
model the luminosity function by a double power-law and find that its evolution
cannot be described by either pure luminosity or pure density evolution, but
must be a combination of both. Our best-fit model has bright and faint
power-law indices consistent with the low redshift measurements based on the
2QZ and 2SLAQ surveys and it generally agrees with the number of bright quasars
predicted by other LFs at all redshifts. If we construct the QSO luminosity
function using only the IRAC-selected AGNs, we find that the biases inherent to
this selection method significantly modify the behavior of phi*(z) only for z<1
and have no significant impact upon the characteristic magnitude M*_J(z).Comment: Corrected minor typo in equations (4) and (6). Accepted for
publication in The Astrophysical Journal. 56 pages + 6 tables + 16 figure
Mid-IR Luminosities and UV/Optical Star Formation Rates at z<1.4
UV continuum and mid-IR emission constitute two widely used star formation
indicators at intermediate and high redshifts. We study 2430 galaxies with
z<1.4 in the Extended Groth Strip with MIPS 24 mic observations from FIDEL,
spectroscopy from DEEP2, and UV, optical, and near-IR photometry from AEGIS.
The data are coupled with stellar population models and Bayesian SED fitting to
estimate dust-corrected SFRs. In order to probe the dust heating from stellar
populations of various ages, the derived SFRs were averaged over various
timescales--from 100 Myr for "current" SFR to 1--3 Gyr for long-timescale SFRs.
These SED-based UV/optical SFRs are compared to total infrared luminosities
extrapolated from 24 mic observations. We find that for the blue, actively star
forming galaxies the correlation between the IR luminosity and the UV/optical
SFR shows a decrease in scatter when going from shorter to longer SFR-averaging
timescales. We interpret this as the greater role of intermediate age stellar
populations in heating the dust than what is typically assumed. This holds over
the entire redshift range. Many so-called green valley galaxies are simply
dust-obscured actively star-forming galaxies. However, there exist 24
mic-detected galaxies, some with L>10^11 L_sun, yet with little current star
formation. For them a reasonable amount of dust absorption of stellar light is
sufficient to produce the observed levels of IR. In our sample optical and
X-ray AGNs do not contribute on average more than ~50% to the mid-IR
luminosity, and we see no evidence for a large population of "IR excess"
galaxies (Abridged).Comment: Accepted for publication in ApJ. Content identical to arXiv version
1. No color figure
Low Resolution Spectral Templates For AGNs and Galaxies From 0.03 -- 30 microns
We present a set of low resolution empirical SED templates for AGNs and
galaxies in the wavelength range from 0.03 to 30 microns based on the
multi-wavelength photometric observations of the NOAO Deep-Wide Field Survey
Bootes field and the spectroscopic observations of the AGN and Galaxy Evolution
Survey. Our training sample is comprised of 14448 galaxies in the redshift
range 0<~z<~1 and 5347 likely AGNs in the range 0<~z<~5.58. We use our
templates to determine photometric redshifts for galaxies and AGNs. While they
are relatively accurate for galaxies, their accuracies for AGNs are a strong
function of the luminosity ratio between the AGN and galaxy components.
Somewhat surprisingly, the relative luminosities of the AGN and its host are
well determined even when the photometric redshift is significantly in error.
We also use our templates to study the mid-IR AGN selection criteria developed
by Stern et al.(2005) and Lacy et al.(2004). We find that the Stern et
al.(2005) criteria suffers from significant incompleteness when there is a
strong host galaxy component and at z =~ 4.5, when the broad Halpha emission
line is redshifted into the [3.6] band, but that it is little contaminated by
low and intermediate redshift galaxies. The Lacy et al.(2004) criterion is not
affected by incompleteness at z =~ 4.5 and is somewhat less affected by strong
galaxy host components, but is heavily contaminated by low redshift star
forming galaxies. Finally, we use our templates to predict the color-color
distribution of sources in the upcoming WISE mission and define a color
criterion to select AGNs analogous to those developed for IRAC photometry. We
estimate that in between 640,000 and 1,700,000 AGNs will be identified by these
criteria, but will have serious completeness problems for z >~ 3.4.Comment: Accepted for publication in The Astrophysical Journal. 26 text pages
+ 3 tables + 20 figures, modified to include comments made by the referee.
Fortran codes, templates and electronic tables available at
http://www.astronomy.ohio-state.edu/~rjassef/lrt
3C 220.3: a radio galaxy lensing a submillimeter galaxy
Herschel Space Observatory photometry and extensive multiwavelength followup
have revealed that the powerful radio galaxy 3C 220.3 at z=0.685 acts as a
gravitational lens for a background submillimeter galaxy (SMG) at z=2.221. At
an observed wavelength of 1mm, the SMG is lensed into three distinct images. In
the observed near infrared, these images are connected by an arc of 1.8" radius
forming an Einstein half-ring centered near the radio galaxy. In visible light,
only the arc is apparent. 3C 220.3 is the only known instance of strong
galaxy-scale lensing by a powerful radio galaxy not located in a galaxy cluster
and therefore it offers the potential to probe the dark matter content of the
radio galaxy host. Lens modeling rejects a single lens, but two lenses centered
on the radio galaxy host A and a companion B, separated by 1.5", provide a fit
consistent with all data and reveal faint candidates for the predicted fourth
and fifth images. The model does not require an extended common dark matter
halo, consistent with the absence of extended bright X-ray emission on our
Chandra image. The projected dark matter fractions within the Einstein radii of
A (1.02") and B (0.61") are about 0.4 +/- 0.3 and 0.55 +/- 0.3. The mass to
i-band light ratios of A and B, M/L ~ 8 +/- 4 Msun/Lsun, appear comparable to
those of radio-quiet lensing galaxies at the same redshift in the CASTLES, LSD,
and SL2S samples. The lensed SMG is extremely bright with observed f(250um) =
440mJy owing to a magnification factor mu~10. The SMG spectrum shows luminous,
narrow CIV 154.9nm emission, revealing that the SMG houses a hidden quasar in
addition to a violent starburst. Multicolor image reconstruction of the SMG
indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive
of cones through which UV light escapes a dust-enshrouded nucleus.Comment: 17 pages, 14 Figures, accepted for publication in Ap
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