403 research outputs found
The Effect of Mood-Context on Visual Recognition and Recall Memory
Although it is widely known that memory is enhanced when encoding and retrieval occur in the same state, the impact of elevated stress/arousal is less understood. This study explores mood-dependent memory's effects on visual recognition and recall of material memorized either in a neutral mood or under higher stress/arousal levels. Participants’ (N = 60) recognition and recall were assessed while they experienced either the same or a mismatched mood at retrieval. The results suggested that both visual recognition and recall memory were higher when participants experienced the same mood at encoding and retrieval compared with those who experienced a mismatch in mood context between encoding and retrieval. These findings offer support for a mood dependency effect on both the recognition and recall of visual information
Fetal liver blood flow distribution: role in human developmental strategy to prioritize fat deposition versus brain development
Among primates, human neonates have the largest brains but also the highest proportion of body fat. If placental nutrient supply is limited, the fetus faces a dilemma: should resources be allocated to brain growth, or to fat deposition for use as a potential postnatal energy reserve? We hypothesised that resolving this dilemma operates at the level of umbilical blood distribution entering the fetal liver. In 381 uncomplicated pregnancies in third trimester, we measured blood flow perfusing the fetal liver, or bypassing it via the ductus venosus to supply the brain and heart using ultrasound techniques. Across the range of fetal growth and independent of the mother's adiposity and parity, greater liver blood flow was associated with greater offspring fat mass measured by dual-energy X-ray absorptiometry, both in the infant at birth (r = 0.43, P<0.001) and at age 4 years (r = 0.16, P = 0.02). In contrast, smaller placentas less able to meet fetal demand for essential nutrients were associated with a brain-sparing flow pattern (r = 0.17, p = 0.02). This flow pattern was also associated with a higher degree of shunting through ductus venosus (P = 0.04). We propose that humans evolved a developmental strategy to prioritize nutrient allocation for prenatal fat deposition when the supply of conditionally essential nutrients requiring hepatic inter-conversion is limited, switching resource allocation to favour the brain if the supply of essential nutrients is limited. Facilitated placental transfer mechanisms for glucose and other nutrients evolved in environments less affluent than those now prevalent in developed populations, and we propose that in circumstances of maternal adiposity and nutrient excess these mechanisms now also lead to prenatal fat deposition. Prenatal developmental influences play important roles in the human propensity to deposit fa
The impact of target frequency on intra-individual variability in euthymic bipolar disorder: a comparison of two sustained attention tasks.
Greater intra-individual variability (IIV) in reaction time (RT) on a sustained attention task has been reported in patients with bipolar disorder (BD) compared with healthy controls. However, it is unclear whether IIV is task specific, or whether it represents general crosstask impairment in BD. This study aimed to investigate whether IIV occurs in sustained attention tasks with different parameters. Twenty-two patients with BD (currently euthymic) and 17 controls completed two sustained attention tasks on different occasions: a low target frequency (~20%) Vigil continuous performance test (CPT) and a high target frequency (~70%) CPT version A-X (CPT-AX). Variability measures (individual standard deviation and coefficient of variation) were calculated per participant, and ex-Gaussian modeling was also applied. This was supplemented by Vincentile analysis to characterize RT distributions. Results indicated that participants (patients and controls) were generally slower and more variable when completing the Vigil CPT compared with CPT-AX. Significant group differences were also observed in the Vigil CPT, with euthymic BD patients being more variable than controls. This result suggests that IIV in BD demonstrates some degree of task specificity. Further research should incorporate analysis of additional RT distributional models (drift diffusion and fast Fourier transform) to fully characterize the pattern of IIV in BD, as well as its relationship to cognitive processes
Detection and molecular characterisation of Cryptosporidium parvum in British European hedgehogs (Erinaceus europaeus)
Surveillance was conducted for the occurrence of protozoan parasites of the genus Cryptosporidium in European hedgehogs (Erinaceus europaeus) in Great Britain. In total, 108 voided faecal samples were collected from hedgehogs newly admitted to eight wildlife casualty treatment and rehabilitation centres. Terminal large intestinal (LI) contents from three hedgehog carcasses were also analysed. Information on host and location variables, including faecal appearance, body weight, and apparent health status, was compiled. Polymerase Chain Reaction (PCR) targeting the 18S ribosomal RNA gene, confirmed by sequencing, revealed an 8% (9/111) occurrence of Cryptosporidium parvum in faeces or LI contents, with no significant association between the host or location variables and infection. Archived small intestinal (SI) tissue from a hedgehog with histological evidence of cryptosporidiosis was also positive for C. parvum by PCR and sequence analysis of the 18S rRNA gene. No other Cryptosporidium species were detected. PCR and sequencing of the glycoprotein 60 gene identified three known zoonotic C. parvum subtypes not previously found in hedgehogs: IIdA17G1 (n=4), IIdA19G1 (n=1) and IIdA24G1 (n=1). These subtypes are also known to infect livestock. Another faecal sample contained C. parvum IIcA5G3j which has been found previously in hedgehogs, and for which there is one published report in a human, but is not known to affect livestock. The presence of zoonotic subtypes of C. parvum in British hedgehogs highlights a potential public health concern. Further research is needed to better understand the epidemiology and potential impacts of Cryptosporidium infection in hedgehogs
Properties and nature of Be stars: 29. Orbital and long-term spectral variations of \gamma\ Cassiopei\ae
A detailed analysis of more than 800 electronic high-resolution spectra of
gamma Cas, which were obtained during a time interval of over 6000 days (16.84
yrs) at several observatories, documents the smooth variations in the density
and/or extend of its circumstellar envelope. We found a clear anticorrelation
between the peak intensity and FWHM of the H alpha emission, which seems to
agree with recent models of such emission lines. The main result of this study
is a confirmation of the binary nature of the object, determination of a
reliable linear ephemeris T_{min.RV} = HJD (2452081.90.6) +
(203.520.08)*E, and a rather definitive set of orbital elements. We
clearly demonstrated that the orbit is circular within the limits of accuracy
of our measurements and has a semi-amplitude of radial-velocity curve of
4.300.09 (km/s). No trace of the low-mass secondary was found. The time
distribution of our spectra does not allow a reliable investigation of rapid
spectral variations, which are undoubtedly present in the spectra. We postpone
this investigation for a future study, based on series of dedicated whole-night
spectral observations
A Hot Gap Around Jupiter's Orbit in the Solar Nebula
The Sun was an order of magnitude more luminous during the first few hundred
thousand years of its existence, due in part to the gravitational energy
released by material accreting from the Solar nebula. If Jupiter was already
near its present mass, the planet's tides opened an optically-thin gap in the
nebula. We show using Monte Carlo radiative transfer calculations that sunlight
absorbed by the nebula and re-radiated into the gap raised temperatures well
above the sublimation threshold for water ice, with potentially drastic
consequences for the icy bodies in Jupiter's feeding zone. Bodies up to a meter
in size were vaporized within a single orbit if the planet was near its present
location during this early epoch. Dust particles lost their ice mantles, and
planetesimals were partially to fully devolatilized, depending on their size.
Scenarios in which Jupiter formed promptly, such as those involving a
gravitational instability of the massive early nebula, must cope with the high
temperatures. Enriching Jupiter in the noble gases through delivery trapped in
clathrate hydrates will be more difficult, but might be achieved by either
forming the planet much further from the star, or capturing planetesimals at
later epochs. The hot gap resulting from an early origin for Jupiter also would
affect the surface compositions of any primordial Trojan asteroids.Comment: 25 pages, 10 figures. ApJ in press. Discussion of Jupiter's volatile
enrichment revised in sec. 4.
Radiative equilibrium in Monte Carlo radiative transfer using frequency distribution adjustment
The Monte Carlo method is a powerful tool for performing radiative
equilibrium calculations, even in complex geometries. The main drawback of the
standard Monte Carlo radiative equilibrium methods is that they require
iteration, which makes them numerically very demanding. Bjorkman & Wood
recently proposed a frequency distribution adjustment scheme, which allows
radiative equilibrium Monte Carlo calculations to be performed without
iteration, by choosing the frequency of each re-emitted photon such that it
corrects for the incorrect spectrum of the previously re-emitted photons.
Although the method appears to yield correct results, we argue that its
theoretical basis is not completely transparent, and that it is not completely
clear whether this technique is an exact rigorous method, or whether it is just
a good and convenient approximation. We critically study the general problem of
how an already sampled distribution can be adjusted to a new distribution by
adding data points sampled from an adjustment distribution. We show that this
adjustment is not always possible, and that it depends on the shape of the
original and desired distributions, as well as on the relative number of data
points that can be added. Applying this theorem to radiative equilibrium Monte
Carlo calculations, we provide a firm theoretical basis for the frequency
distribution adjustment method of Bjorkman & Wood, and we demonstrate that this
method provides the correct frequency distribution through the additional
requirement of radiative equilibrium. We discuss the advantages and limitations
of this approach, and show that it can easily be combined with the presence of
additional heating sources and the concept of photon weighting. However, the
method may fail if small dust grains are included... (abridged)Comment: 17 pages, 2 figures, accepted for publication in New Astronom
Young people in iNaturalist: a blended learning framework for biodiversity monitoring
Participation in authentic research in the field and online through Community and Citizen Science (CCS) has shown to bring learning benefits to volunteers. In online CCS, available platforms present distinct features, ranging from scaffolding the process of data collection, to supporting data analysis and enabling volunteers to initiate their own studies. What is yet not well understood is how best to design CCS programmes that are educational, inclusive, and accessible by diverse volunteers, including young people and those with limited prior science experiences who are rather few in CCS. In this study, we interviewed 31 young people, aged 7–20 years old, who used iNaturalist, an online biodiversity monitoring platform, and identified how different forms of participation online and in the field facilitated (or inhibited) certain forms of learning, as defined by the Environmental Science Agency framework. Findings revealed that iNaturalist enabled participation of young people including those with limited science experiences and facilitated science learning such as the development of science competence and understanding. A blended learning framework for biodiversity monitoring in CCS is presented as a means to support the development of hybrid, educational, and inclusive CCS programmes for young people
Complexity reduction and policy consensus: asylum seekers, the right to work, and the ‘pull factor’ thesis in the UK context
Since the early 2000s, asylum policy in Western states has become increasingly dominated by the
concept of the ‘pull factor’—the idea that the economic rights afforded to asylum seekers can
act as a migratory pull, and will have a bearing on the numbers of asylum applications received.
The pull factor thesis has been widely discredited by researchers but remains powerful among
policymakers. Through an analysis of the pull factor in the UK context, and drawing on insights
from Cultural Political Economy, this article argues that the hegemony of the pull factor thesis is
best understood as a ‘policy imaginary’ which has become sedimented through both discursive
and extra-discursive practices and processes. The article offers a means of understanding how
a common sense assumption—which is challenged by a large body of evidence—has come to
dominate policymaking in a key area of concern for politicians and policymakers
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