1,271 research outputs found
Long-range orbitofrontal and amygdala axons show divergent patterns of maturation in the frontal cortex across adolescence.
The adolescent transition from juvenile to adult is marked by anatomical and functional remodeling of brain networks. Currently, the cellular and synaptic level changes underlying the adolescent transition are only coarsely understood. Here, we use two-photon imaging to make time-lapse observations of long-range axons that innervate the frontal cortex in the living brain. We labeled cells in the orbitofrontal cortex (OFC) and basolateral amygdala (BLA) and imaged their axonal afferents to the dorsomedial prefrontal cortex (dmPFC). We also imaged the apical dendrites of dmPFC pyramidal neurons. Images were taken daily in separate cohorts of juvenile (P24-P28) and young adult mice (P64-P68), ages where we have previously discovered differences in dmPFC dependent decision-making. Dendritic spines were pruned across this peri-adolescent period, while BLA and OFC afferents followed alternate developmental trajectories. OFC boutons showed no decrease in density, but did show a decrease in daily bouton gain and loss with age. BLA axons showed an increase in both bouton density and daily bouton gain at the later age, suggesting a delayed window of enhanced plasticity. Our findings reveal projection specific maturation of synaptic structures within a single frontal region and suggest that stabilization is a more general characteristic of maturation than pruning
Studying Brain Function in Children Using Magnetoencephalography
Magnetoencephalography (MEG) is a non-invasive neuroimaging technique which directly measures magnetic fields produced by the electrical activity of the human brain. MEG is quiet and less likely to induce claustrophobia compared with magnetic resonance imaging (MRI). It is therefore a promising tool for investigating brain function in young children. However, analysis of MEG data from pediatric populations is often complicated by head movement artefacts which arise as a consequence of the requirement for a spatially-fixed sensor array that is not affixed to the child's head. Minimizing head movements during MEG sessions can be particularly challenging as young children are often unable to remain still during experimental tasks. The protocol presented here aims to reduce head movement artefacts during pediatric MEG scanning. Prior to visiting the MEG laboratory, families are provided with resources that explain the MEG system and the experimental procedures in simple, accessible language. An MEG familiarization session is conducted during which children are acquainted with both the researchers and the MEG procedures. They are then trained to keep their head still whilst lying inside an MEG simulator. To help children feel at ease in the novel MEG environment, all of the procedures are explained through the narrative of a space mission. To minimize head movement due to restlessness, children are trained and assessed using fun and engaging experimental paradigms. In addition, children's residual head movement artefacts are compensated for during the data acquisition session using a real-time head movement tracking system. Implementing these child-friendly procedures is important for improving data quality, minimizing participant attrition rates in longitudinal studies, and ensuring that families have a positive research experience
Trends and factors associated with illicit drug use in South Africa : findings from multiple national population-based household surveys, 2002–2017
DATA SHARING :
The HSRC data are freely available upon request through the HSRC's digital repository via http://datacuration.hsrc.ac.za/.BACKGROUND :
Illicit drug use results in considerable global morbidity, but there is little data on its trends and factors associated with it in sub-Saharan Africa. We consider these questions using national data from South Africa for 2002–2017.
METHODS :
We analysed data among individuals aged 15 years or older from five national population-based household surveys in South Africa (2002–2017; n = 89,113). Recent drug use was defined as the last three-months use of illicit drugs, i.e., any use of cannabis, cocaine, amphetamine, inhalants, sedatives, hallucinogens, opioids, and/or other illicit drugs. Time trends in recent drug use were assessed using logistic regression. Multivariable logistic regression assessed the association between recent drug use and socio-demographic factors and between drug use and sexual risk behaviours, HIV-related and other well-being variables.
RESULTS :
The prevalence of recent drug use increased from 1·5% to 10·0% from 2002 to 2017, driven by increases in cannabis use (1·5% to 7·8%) and use of opioids (0·01% to 1·6%), cocaine (0·02% to 1·8%), or amphetamines (0·1% to 1·5%). In adjusted analyses, male gender, younger age, living in urban areas, mixed-ancestry or white ethnicity (compared to black-African), and unemployment were positively associated with recent drug use. Recent drug use was associated with: multiple sexual partners (adjusted odds ratio [aOR] 2·13, 95% confidence interval [CI]: 1·80–2·51); sexual debut before 15 years old (aOR 1·70, 95%CI: 1·29–2·23); hazardous/harmful alcohol use (aOR 2·50, 95%CI: 2·14–2·93) or alcohol dependence (aOR 3·33, 95%CI 2·92–3·80); ever experiencing intimate partner violence (aOR 1·56, 95%CI 1·12–2·17); psychological distress (aOR 1·53, 95%CI: 1·28–1·82); and lower chance of ever testing for HIV (aOR 0·89, 95%CI 0·80–1·00). Recent drug use was not associated with HIV positivity, condom use or being on antiretroviral therapy.
CONCLUSION :
Illicit drug use has increased substantially in South Africa and is associated with numerous socio-demographic characteristics, higher sexual risk behaviours and other well-being variables.https://www.elsevier.com/locate/drugpohj2024Family MedicineSDG-03:Good heatlh and well-bein
Seeing the landscape for the trees: metrics to guide riparian shade management in river catchments
Rising water temperature (Tw) due to anthropogenic climate change may have serious consequences for river ecosystems. Conservation and/or expansion of riparian shade could counter warming and buy time for ecosystems to adapt. However, sensitivity of river reaches to direct solar radiation is highly heterogeneous in space and time, so benefits of shading are also expected to be site specific. We use a network of high-resolution temperature measurements from two upland rivers in the UK, in conjunction with topographic shade modelling, to assess the relative significance of landscape and riparian shade to the thermal behaviour of river reaches. Trees occupy 7% of the study catchments (comparable with the UK national average) yet shade covers 52% of the area and is concentrated along river corridors. Riparian shade is most beneficial for managing Tw at distances 5 to 20 km downstream from the source of the rivers where discharge is modest, flow is dominated by near-surface hydrological pathways, there is a wide floodplain with little landscape shade, and where cumulative solar exposure times are sufficient to affect Tw. For the rivers studied, we find that approximately 0.5 km of complete shade is necessary to off-set Tw by 1°C during July (the month with peak Tw) at a headwater site; whereas 1.1 km of shade is required 25 km downstream. Further research is needed to assess the integrated effect of future changes in air temperature, sunshine duration, direct solar radiation and downward diffuse radiation on Tw to help tree planting schemes achieve intended outcomes
Response to novel objects and foraging tasks by common marmoset (Callithrix Jacchus) female Pairs
Many studies have shown that environmental enrichment can significantly improve the psychological well-being of captive primates, increasing the occurrence of explorative behavior and thus reducing boredom. The response of primates to enrichment devices may be affected by many factors such as species, sex, age, personality and social context. Environmental enrichment is particularly important for social primates living in unnatural social groupings (i.e. same-sex pairs or singly housed animals), who have very few, or no, benefits from the presence of social companions in addition to all the problems related to captivity (e.g. increased inactivity). This study analyses the effects of enrichment devices (i.e. novel objects and foraging tasks) on the behavior of common marmoset (Callithrix jacchus) female pairs, a species that usually lives in family groups. It aims to determine which aspects of an enrichment device are more likely to elicit explorative behaviors, and how aggressive and stress-related behaviors are affected by its presence. Overall, the marmosets explored foraging tasks significantly longer than novel objects. The type of object, which varied in size, shape and aural responsiveness (i.e. they made a noise when the monkey touched them), did not affect the response of the monkeys, but they explored objects that were placed higher in the enclosure more than those placed lower down.Younger monkeys were more attracted to the enrichment devices than the older ones. Finally, stress-related behavior (i.e. scratching) significantly decreased when the monkeys were presented with the objects; aggressive behavior as unaffected. This study supports the importance of environmental enrichment for captive primates and shows that in marmosets its effectiveness strongly depends upon the height of the device in the enclosure and the presence of hidden food. The findings can be explained ifone considers the foraging behavior of wild common marmosets. Broader applications for the research findings are suggested in relation to enrichment
LHC sensitivity to the resonance spectrum of a minimal strongly interacting electroweak symmetry breaking sector
We present a unified analysis of the two main production processes of vector
boson pairs at the LHC, VV-fusion and qqbar annihilation, in a minimal strongly
interacting electroweak symmetry breaking sector. Using a unitarized
electroweak chiral Lagrangian formalism and modeling the final V_L V_L strong
rescattering effects by a form factor, we describe qqbar annihilation processes
in terms of the two chiral parameters that govern elastic V_L V_L scattering.
Depending on the values of these two chiral parameters, the unitarized
amplitudes may present resonant enhancements in different angular
momentum-isospin channels. Scanning this two parameter space, we generate the
general resonance spectrum of a minimal strongly interacting electroweak
symmetry breaking sector and determine the regions that can be probed at the
LHC.Comment: Final version to appear in Phys. Rev. D, including a more detailed
exposition and a few more references. Conclusions and results unchanged. 14
pages, 5 figure
Ischaemic strokes in patients with pulmonary arteriovenous malformations and hereditary hemorrhagic telangiectasia: associations with iron deficiency and platelets.
<div><p>Background</p><p>Pulmonary first pass filtration of particles marginally exceeding ∼7 µm (the size of a red blood cell) is used routinely in diagnostics, and allows cellular aggregates forming or entering the circulation in the preceding cardiac cycle to lodge safely in pulmonary capillaries/arterioles. Pulmonary arteriovenous malformations compromise capillary bed filtration, and are commonly associated with ischaemic stroke. Cohorts with CT-scan evident malformations associated with the highest contrast echocardiographic shunt grades are known to be at higher stroke risk. Our goal was to identify within this broad grouping, which patients were at higher risk of stroke.</p><p>Methodology</p><p>497 consecutive patients with CT-proven pulmonary arteriovenous malformations due to hereditary haemorrhagic telangiectasia were studied. Relationships with radiologically-confirmed clinical ischaemic stroke were examined using logistic regression, receiver operating characteristic analyses, and platelet studies.</p><p>Principal Findings</p><p>Sixty-one individuals (12.3%) had acute, non-iatrogenic ischaemic clinical strokes at a median age of 52 (IQR 41–63) years. In crude and age-adjusted logistic regression, stroke risk was associated not with venous thromboemboli or conventional neurovascular risk factors, but with low serum iron (adjusted odds ratio 0.96 [95% confidence intervals 0.92, 1.00]), and more weakly with low oxygen saturations reflecting a larger right-to-left shunt (adjusted OR 0.96 [0.92, 1.01]). For the same pulmonary arteriovenous malformations, the stroke risk would approximately double with serum iron 6 µmol/L compared to mid-normal range (7–27 µmol/L). Platelet studies confirmed overlooked data that iron deficiency is associated with exuberant platelet aggregation to serotonin (5HT), correcting following iron treatment. By MANOVA, adjusting for participant and 5HT, iron or ferritin explained 14% of the variance in log-transformed aggregation-rate (p = 0.039/p = 0.021).</p><p>Significance</p><p>These data suggest that patients with compromised pulmonary capillary filtration due to pulmonary arteriovenous malformations are at increased risk of ischaemic stroke if they are iron deficient, and that mechanisms are likely to include enhanced aggregation of circulating platelets.</p></div
Association between footwear use and neglected tropical diseases: a systematic review and meta-analysis
BACKGROUND
The control of neglected tropical diseases (NTDs) has primarily focused on preventive chemotherapy and case management. Less attention has been placed on the role of ensuring access to adequate water, sanitation, and hygiene and personal preventive measures in reducing exposure to infection. Our aim was to assess whether footwear use was associated with a lower risk of selected NTDs.
METHODOLOGY
We conducted a systematic review and meta-analysis to assess the association between footwear use and infection or disease for those NTDs for which the route of transmission or occurrence may be through the feet. We included Buruli ulcer, cutaneous larva migrans (CLM), leptospirosis, mycetoma, myiasis, podoconiosis, snakebite, tungiasis, and soil-transmitted helminth (STH) infections, particularly hookworm infection and strongyloidiasis. We searched Medline, Embase, Cochrane, Web of Science, CINAHL Plus, and Popline databases, contacted experts, and hand-searched reference lists for eligible studies. The search was conducted in English without language, publication status, or date restrictions up to January 2014. Studies were eligible for inclusion if they reported a measure of the association between footwear use and the risk of each NTD. Publication bias was assessed using funnel plots. Descriptive study characteristics and methodological quality of the included studies were summarized. For each study outcome, both outcome and exposure data were abstracted and crude and adjusted effect estimates presented. Individual and summary odds ratio (OR) estimates and corresponding 95% confidence intervals (CIs) were calculated as a measure of intervention effect, using random effects meta-analyses.
PRINCIPAL FINDINGS
Among the 427 studies screened, 53 met our inclusion criteria. Footwear use was significantly associated with a lower odds of infection of Buruli ulcer (OR=0.15; 95% CI: 0.08-0.29), CLM (OR=0.24; 95% CI: 0.06-0.96), tungiasis (OR=0.42; 95% CI: 0.26-0.70), hookworm infection (OR=0.48; 95% CI: 0.37-0.61), any STH infection (OR=0.57; 95% CI: 0.39-0.84), strongyloidiasis (OR=0.56; 95% CI: 0.38-0.83), and leptospirosis (OR=0.59; 95% CI: 0.37-0.94). No significant association between footwear use and podoconiosis (OR=0.63; 95% CI: 0.38-1.05) was found and no data were available for mycetoma, myiasis, and snakebite. The main limitations were evidence of heterogeneity and poor study quality inherent to the observational studies included.
CONCLUSIONS/SIGNIFICANCE
Our results show that footwear use was associated with a lower odds of several different NTDs. Access to footwear should be prioritized alongside existing NTD interventions to ensure a lasting reduction of multiple NTDs and to accelerate their control and elimination.
PROTOCOL REGISTRATION
PROSPERO International prospective register of systematic reviews CRD42012003338
Preliminary Integrated Chronostratigraphy of the AND-2A Core, ANDRILL Southern McMurdo Sound Project, Antarctica
We use all available chronostratigraphic constraints – biostratigraphy, magnetostratigraphy,
radioisotopic dates, strontium-isotope stratigraphy, and correlation of compositional and physical properties
to well-dated global or regional records – to construct a preliminary age model for ANDRILL SMS Project’s
AND-2A drillcore (77°45.488’S, 165°16.605’E, 383.57 m water depth). These diverse chronostratigraphic
constraints are consistent with each other and are distributed throughout the 1138.54 m-thick section,
resulting in a well-constrained age model. The sedimentary succession comprises a thick early and middle
Miocene section below 224.82 mbsf and a condensed middle/late Miocene to Recent section above
this. The youngest sediments are Brunhes age (<0.781 Ma), as confirmed by a radioisotopic age of
0.691±0.049 Ma at 10.23 mbsf and the occurrence of sediments that have normal magnetic polarity down
to ~31.1 mbsf, which is interpreted to be the Brunhes/Matuyama reversal (0.781 Ma). The upper section
is punctuated by disconformities resulting from both discontinuous deposition and periods of extensive
erosion typical of sedimentary environments at the margin of a dynamic ice sheet. Additional breaks in
the section may be due to the influence of tectonic processes. The age model incorporates several major
hiatuses but their precise depths are still somewhat uncertain, as there are a large number of erosional
surfaces identified within the stratigraphic section. One or more hiatuses, which represent a total 7 to 8
million years of time missing from the sedimentary record, occur between about 50 mbsf and the base of
Lithostratigraphic Unit (LSU) 3 at 122.86 mbsf. Similarly, between about 145 mbsf and the base of LSU
4 at 224.82 mbsf, one or more hiatuses occur on which another 2 to 3 million years of the sedimentary
record is missing. Support for the presence of these hiatuses comes from a diatom assemblage that
constrains the age of the core from 44 to 50 mbsf to 2.06-2.84 Ma, two radioisotopic dates (11.4 Ma)
and a Sr‑isotope date (11.7 Ma) that indicate the interval from 127 to 145 mbsf was deposited between
11.4 and 11.7 Ma, and three diatom occurrence datums from between 225.38 and 278.55 mbsf that
constrain the age of this upper part of Lithostratigraphic Unit (LSU) 5 to 14.29 - 15.89 Ma. Below the
boundary between LSU 5 and 6 sedimentation was relatively continuous and rapid and the age model is
well-constrained by 9 diatom datums, seven 40Ar-39Ar dates, one Sr-isotope date, and 19 magnetozones.
Even so, short hiatuses (less than a few hundred thousand years) undoubtedly occur but are beyond
the resolution of current chronostratigraphic age constraints. Diatom first and last occurrence datums
provide particularly good age control from the top of LSU 6 down to 771.5 mbsf (in LSU 10), where
the First Occurrence (FO) of Thalassiosira praefraga (18.85 Ma) is observed. The diatom datum ages
are supported by radioisotopic dates of 17.30±0.31 Ma at 640.14 mbsf (in LSU 9) and 18.15±0.35 and
17.93±0.40 Ma for samples from 709.15 and 709.18 mbsf (in LSU 10), respectively, and 18.71±0.33 Ma
for a sample from 831.67 mbsf (in LSU 11). The sediments from 783.69 mbsf to the base of the hole
comprise two thick normal polarity magnetozones that bound a thinner reversed polarity magnetozone
(958.59 - 985.64 mbsf). This polarity sequence most likely encompasses Chrons C5En, C5Er, and C6n
(18.056 - 19.772 Ma or slightly older given uncertainties in this section of the geomagnetic polarity
timescale), but could be also be Chrons C6n, C6r, and C6An.1n (18.748 - 20.213 Ma). Either polarity
sequence is compatible with the 40Ar–39Ar age of 20.01±0.35 Ma obtained from single-grain analyses of
alkali feldspar from a tephra sample from a depth of 1093.02 mbsf, although the younger interpretation
allows a better fit with chronostratigraphic data up-core. Given this age model, the mean sedimentation
rate is about 18 cm/k.y. from the top of LSU 6 to the base of the hole.Published221-2202.2. Laboratorio di paleomagnetismoN/A or not JCRreserve
- …