1,451 research outputs found
Atomic and Molecular Absorption in Redshifted Radio Sources
We report on a survey for associated HI 21-cm and OH 18-cm absorption with
the Giant Metrewave Radio Telescope at redshifts z = 0.2-0.4. Although the low
redshift selection ensures that our targets are below the critical ultra-violet
luminosity, which is hypothesised to ionise all of the neutral gas in the host
galaxy, we do not obtain any detections in the six sources searched. Analysing
these in context of the previous surveys, in addition to the anti-correlation
with the ultra-violet luminosity (ionising photon rate), we find a correlation
between the strength of the absorption and the blue -- near-infrared colour, as
well as the radio-band turnover frequency. We believe that these are due to the
photo-ionisation of the neutral gas, an obscured sight-line being more
conducive to the presence of cold gas and the compact radio emission being
better intercepted by the absorbing gas, maximising the flux coverage,
respectively. Regarding the photo-ionisation, the compilation of the previous
surveys increases the significance of the critical ionising photon rate, above
which all of the gas in the host galaxy is hypothesised to be ionised, to >5
sigma. This reaffirms that this is an ubiquitous effect, which has profound
implications for the detection of neutral gas in these objects with the Square
Kilometre Array.Comment: Accepted by MNRA
PKSB1740-517: An ALMA view of the cold gas feeding a distant interacting young radio galaxy
Cold neutral gas is a key ingredient for growing the stellar and central
black hole mass in galaxies throughout cosmic history. We have used the Atacama
Large Millimetre Array (ALMA) to detect a rare example of redshifted
CO(2-1) absorption in PKS B1740-517, a young (
yr) and luminous ( erg s ) radio
galaxy at that is undergoing a tidal interaction with at least one
lower-mass companion. The coincident HI 21-cm and molecular absorption have
very similar line profiles and reveal a reservoir of cold gas ( M), likely distributed in a disc or ring within
a few kiloparsecs of the nucleus. A separate HI component is kinematically
distinct and has a very narrow line width ( km
s), consistent with a single diffuse cloud of cold (
K) atomic gas. The CO(2-1) absorption is not associated with this
component, which suggests that the cloud is either much smaller than 100 pc
along our sight-line and/or located in low-metallicity gas that was possibly
tidally stripped from the companion. We argue that the gas reservoir in PKS
B1740-517 may have accreted onto the host galaxy 50 Myr before the young
radio AGN was triggered, but has only recently reached the nucleus. This is
consistent with the paradigm that powerful luminous radio galaxies are
triggered by minor mergers and interactions with low-mass satellites and
represent a brief, possibly recurrent, active phase in the life cycle of
massive early type galaxies.Comment: 15 pages, 7 figures, accepted for publication in MNRA
Swimming using surface acoustic waves
Microactuation of free standing objects in fluids is currently dominated by the rotary propeller, giving rise to a range of potential applications in the military, aeronautic and biomedical fields. Previously, surface acoustic waves (SAWs) have been shown to be of increasing interest in the field of microfluidics, where the refraction of a SAW into a drop of fluid creates a convective flow, a phenomenon generally known as SAW streaming. We now show how SAWs, generated at microelectronic devices, can be used as an efficient method of propulsion actuated by localised fluid streaming. The direction of the force arising from such streaming is optimal when the devices are maintained at the Rayleigh angle. The technique provides propulsion without any moving parts, and, due to the inherent design of the SAW transducer, enables simple control of the direction of travel
Exercise therapy in adults with serious mental illness: a systematic review and meta-analysis
Background: Individuals with serious mental illness are at a higher risk of physical ill health. Mortality rates are at least twice those of the general population with higher levels of cardiovascular disease, metabolic disease, diabetes, and respiratory illness. Although genetics may have a role in the physical health problems of these patients, lifestyle and environmental factors such as levels of smoking, obesity, poor diet, and low levels of physical activity also play a prominent part.<p></p>
Objective: To conduct a systematic review and meta-analysis of randomised controlled trials comparing the effect of exercise interventions on individuals with serious mental illness.<p></p>
Methods: Searches were made in Ovid MEDLINE, Embase, CINAHL, PsycINFO, Biological Abstracts on Ovid, and The Cochrane Library (January 2009, repeated January 2013) through to February 2013.<p></p>
Results: Eight RCTs were identified in the systematic search. Six compared exercise versus usual care. One study assessed the effect of a cycling programme versus muscle strengthening and toning exercises. The final study compared the effect of adding specific exercise advice and motivational skills to a simple walking programme. Exercise programmes were noted by their heterogeneity in terms of the type of exercise intervention, setting, and outcome measures. The review found that exercise improved levels of exercise activity (n=13, standard mean difference [SMD] 1.81, CI 0.44 to 3.18, p = 0.01). No beneficial effect was found on negative (n = 84, SMD = -0.54, CI -1.79 to 0.71, p = 0.40) or positive symptoms of schizophrenia (n = 84, SMD = -1.66, CI -3.78 to 0.45, p = 0.12). No change was found on body mass index compared with usual care (n= 151, SMD = -0.24, CI -0.56 to 0.08, p = 0.14), or body weight (n = 77, SMD = 0.13, CI -0.32 to 0.58, p = 0.57).
No beneficial effect was found on anxiety and depressive symptoms (n = 94, SMD = -0.26, CI -0.91 to 0.39, p = 0.43), or quality of life in respect of physical and mental domains. One RCT measured the effect of exercise on exercise intensity, attendance, and persistence at a programme. No significant effect was found on these measures.<p></p>
Conclusions: This systematic review showed that exercise therapies can lead to a modest increase in levels of exercise activity but overall there was no noticeable change for symptoms of mental health, body mass index, and body weight.<p></p>
Age-related delay in information accrual for faces: Evidence from a parametric, single-trial EEG approach
Background: In this study, we quantified age-related changes in the time-course of face processing
by means of an innovative single-trial ERP approach. Unlike analyses used in previous studies, our
approach does not rely on peak measurements and can provide a more sensitive measure of
processing delays. Young and old adults (mean ages 22 and 70 years) performed a non-speeded
discrimination task between two faces. The phase spectrum of these faces was manipulated
parametrically to create pictures that ranged between pure noise (0% phase information) and the
undistorted signal (100% phase information), with five intermediate steps.
Results: Behavioural 75% correct thresholds were on average lower, and maximum accuracy was
higher, in younger than older observers. ERPs from each subject were entered into a single-trial
general linear regression model to identify variations in neural activity statistically associated with
changes in image structure. The earliest age-related ERP differences occurred in the time window
of the N170. Older observers had a significantly stronger N170 in response to noise, but this age
difference decreased with increasing phase information. Overall, manipulating image phase
information had a greater effect on ERPs from younger observers, which was quantified using a
hierarchical modelling approach. Importantly, visual activity was modulated by the same stimulus
parameters in younger and older subjects. The fit of the model, indexed by R2, was computed at
multiple post-stimulus time points. The time-course of the R2 function showed a significantly slower
processing in older observers starting around 120 ms after stimulus onset. This age-related delay
increased over time to reach a maximum around 190 ms, at which latency younger observers had
around 50 ms time lead over older observers.
Conclusion: Using a component-free ERP analysis that provides a precise timing of the visual
system sensitivity to image structure, the current study demonstrates that older observers
accumulate face information more slowly than younger subjects. Additionally, the N170 appears to
be less face-sensitive in older observers
Spanish version of the Oral Health Impact Profile (OHIP-Sp)
BACKGROUND: The need for appraisal of oral health-related quality of life has been increasingly recognized over the last decades. The aims of this study were to develop a Spanish version (OHIP-Sp) of the Oral Health Impact Profile and to evaluate its convergent and discriminative validity, and its internal consistency. METHODS: The original 49-items OHIP was translated to Spanish, revised for understanding and semantics by two independent dentists, and then translated back to English by an independent bilingual dentist. The data originated in a cross sectional study conducted among high school students from the Province of Santiago, Chile. The study group was sampled using a multistage random cluster procedure yielding 9,203 students aged 12–21 years. All selected students were invited to participate and all filled a questionnaire with information on socio-demographic factors; oral health related behaviors; and self-reported oral health status (good, fair or poor). From this group, 9,163 students also accepted to fill a detailed questionnaire on socio-economic indicators and to receive a clinical examination comprising direct recordings of clinical attachment levels (CAL) in molars and incisors, tooth loss, and the presence of necrotizing ulcerative gingival lesions. RESULTS: The participation rate and the questionnaire completeness were high with OHIP-Sp total scores being computed for 9,133 subjects. Self-perceived oral health status was associated with the total OHIP-Sp score and all its domains (Spearman rank correlation). The OHIP-Sp total score was also directly associated with the 4 dental outcomes investigated (Mann-Whitney test) and the largest impact was found for the outcomes, 'tooth loss' with a mean OHIP-Sp score = 13.5 and 'CAL >= 3 mm' with a mean OHIP-Sp score = 13.0. CONCLUSION: The OHIP-Sp revealed suitable convergent and discriminative validity and appropriate internal consistency (Cronbach's α). Further studies on OHIP-Sp warrant the inclusion of populations with a higher disease burden; and the use of test-retest reliability exercises to evaluate the stability of the test
Comparing the Processing of Music and Language Meaning Using EEG and fMRI Provides Evidence for Similar and Distinct Neural Representations
Recent demonstrations that music is capable of conveying semantically meaningful information has raised several questions as to what the underlying mechanisms of establishing meaning in music are, and if the meaning of music is represented in comparable fashion to language meaning. This paper presents evidence showing that expressed affect is a primary pathway to music meaning and that meaning in music is represented in a very similar fashion to language meaning. In two experiments using EEG and fMRI, it was shown that single chords varying in harmonic roughness (consonance/dissonance) and thus perceived affect could prime the processing of subsequently presented affective target words, as indicated by an increased N400 and activation of the right middle temporal gyrus (MTG). Most importantly, however, when primed by affective words, single chords incongruous to the preceding affect also elicited an N400 and activated the right posterior STS, an area implicated in processing meaning of a variety of signals (e.g. prosody, voices, motion). This provides an important piece of evidence in support of music meaning being represented in a very similar but also distinct fashion to language meaning: Both elicit an N400, but activate different portions of the right temporal lobe
Diversity and Strain Specificity of Plant Cell Wall Degrading Enzymes Revealed by the Draft Genome of Ruminococcus flavefaciens FD-1
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