9,732 research outputs found
Global oceanic emission of ammonia: constraints from seawater and atmospheric observations
Current global inventories of ammonia emissions identify the ocean as the largest natural
source. This source depends on seawater pH, temperature, and the concentration of total seawater
ammonia (NHx(sw)), which reflects a balance between remineralization of organic matter, uptake by
plankton, and nitrification. Here we compare [NHx(sw)] from two global ocean biogeochemical models
(BEC and COBALT) against extensive ocean observations. Simulated [NHx(sw)] are generally biased high.
Improved simulation can be achieved in COBALT by increasing the plankton affinity for NHx within observed
ranges. The resulting global ocean emissions is 2.5 TgN aâ1, much lower than current literature values
(7â23 TgN aâ1), including the widely used Global Emissions InitiAtive (GEIA) inventory (8 TgN aâ1). Such
a weak ocean source implies that continental sources contribute more than half of atmospheric NHx over
most of the ocean in the Northern Hemisphere. Ammonia emitted from oceanic sources is insufficient to
neutralize sulfate aerosol acidity, consistent with observations. There is evidence over the Equatorial Pacific
for a missing source of atmospheric ammonia that could be due to photolysis of marine organic nitrogen at
the ocean surface or in the atmosphere. Accommodating this possible missing source yields a global ocean
emission of ammonia in the range 2â5 TgN aâ1, comparable in magnitude to other natural sources from
open fires and soils
Home based exercise programme for knee pain and knee osteoarthritis: randomised controlled trial
Objectives To determine whether a home based
exercise programme can improve outcomes in
patients with knee pain.
Design Pragmatic, factorial randomised controlled
trial of two years' duration.
Setting Two general practices in Nottingham.
Participants 786 men and women aged >45 years
with self reported knee pain.
Interventions Participants were randomised to four
groups to receive exercise therapy, monthly telephone
contact, exercise therapy plus telephone contact, or no
intervention. Patients in the no intervention and
combined exercise and telephone groups were
randomised to receive or not receive a placebo health
food tablet.
Main outcome measures Primary outcome was self
reported score for knee pain on the Western Ontario
and McMaster universities (WOMAC) osteoarthritis
index at two years. Secondary outcomes included
knee specific physical function and stiffness (scored on
WOMAC index), general physical function (scored on
SFÂ36 questionnaire), psychological outlook (scored
on hospital anxiety and depression scale), and
isometric muscle strength.
Results 600 (76.3%) participants completed the study.
At 24 months, highly significant reductions in knee
pain were apparent for the pooled exercise groups
compared with the nonÂexercise groups (mean
difference â0.82, 95% confidence interval â1.3 to
â0.3). Similar improvements were observed at 6, 12,
and 18 months. Regular telephone contact alone did
not reduce pain. The reduction in pain was greater
the closer patients adhered to the exercise plan.
Conclusions A simple home based exercise
programme can significantly reduce knee pain. The
lack of improvement in patients who received only
telephone contact suggests that improvements are not
just due to psychosocial effects because of contact
with the therapist
Atomistic study on the pressure dependence of the melting point of NdFe12
We investigated, using molecular dynamics, how pressure affects the melting point of the recently theorised and epitaxially grown structure NdFe12. We modified Morse potentials using experimental constants and a genetic algorithm code, before running two-phase solid-liquid coexistence simulations of NdFe12 at various temperatures and pressures. The refitting of the Morse potentials allowed us to significantly improve the accuracy in predicting the melting temperature of the constituent elements
Longitudinal Atomic Beam Spin Echo Experiments: A possible way to study Parity Violation in Hydrogen
We discuss the propagation of hydrogen atoms in static electric and magnetic
fields in a longitudinal atomic beam spin echo (lABSE) apparatus. Depending on
the choice of the external fields the atoms may acquire both dynamical and
geometrical quantum mechanical phases. As an example of the former, we show
first in-beam spin rotation measurements on atomic hydrogen, which are in
excellent agreement with theory. Additional calculations of the behaviour of
the metastable 2S states of hydrogen reveal that the geometrical phases may
exhibit the signature of parity-(P-)violation. This invites for possible future
lABSE experiments, focusing on P-violating geometrical phases in the lightest
of all atoms.Comment: 6 pages, 4 figure
Visuo-attentional correlates of Autism Spectrum Disorder (ASD) in children with Down syndrome: A comparative study with children with idiopathic ASD.
BACKGROUND: Children with Down syndrome (DS) are at increased likelihood of Autism Spectrum Disorder (ASD) relative to the general population. To better understand the nature of this comorbidity, we examined the visuo-attentional processes associated with autistic trait expression in children with DS, focusing specifically on attentional disengagement and visual search performance. METHOD: We collected eye-tracking data from children with DS (nâŻ=âŻ15) and children with idiopathic ASD (iASD, nâŻ=âŻ16) matched according to chronological age. Seven children with DS had a formal clinical diagnosis of ASD (DS+ASD). RESULTS: In children with iASD, but not DS, higher autistic trait levels were associated with decreased temporal facilitation on a gap-overlap task, implying increased visuospatial orienting efficiency. In all cases, higher autistic trait levels were associated with improved visual search performance according to decreased target detection latency. On a visual search task, children with DS+ASD outperformed their peers with DS-ASD, mirroring the phenotypic advantage associated with iASD. We found no evidence of a relationship between attentional disengagement and visual search performance, providing preliminary evidence of a differentiation in terms of underlying visuo-attentional mechanism. CONCLUSION: We illustrate the value of progressing beyond insensitive behavioural measures of phenotypic description to examine, in a more fine-grained way, the attentional features associated with ASD comorbidity in children with DS
Probiotics to prevent infantile colic
Background
Infantile colic is typically defined as fullâforce crying for at least three hours per day, on at least three days per week, for at least three weeks. Infantile colic affects a large number of infants and their families worldwide. Its symptoms are broad and general, and while not indicative of disease, may represent a serious underlying condition in a small percentage of infants who may need a medical assessment. Probiotics are live microorganisms that alter the microflora of the host and provide beneficial health effects. The most common probiotics used are of Lactobacillus, Bifidobacterium and Streptococcus. There is growing evidence to suggest that intestinal flora in colicky infants differ from those in healthy infants, and it is suggested that probiotics can redress this balance and provide a healthier intestinal microbiota landscape. The low cost and easy availability of probiotics makes them a potential prophylactic solution to reduce the incidence and prevalence of infantile colic.
Objectives
To evaluate the efficacy and safety of prophylactic probiotics in preventing or reducing severity of infantile colic.
Search methods
In January 2018 we searched CENTRAL, MEDLINE, Embase, PsycINFO, CINAHL, 10 other databases and two trials registers. In addition, we handsearched the abstracts of relevant meetings, searched reference lists, ran citation searches of included studies, and contacted authors and experts in the field, including the manufacturers of probiotics, to identify unpublished trials.
Selection criteria
Randomised control trials (RCTs) of newborn infants less than one month of age without the diagnosis of infantile colic at recruitment. We included any probiotic, alone or in combination with a prebiotic (also known as synbiotics), versus no intervention, another intervention(s) or placebo, where the focus of the study was the effect of the intervention on infantile colic.
Data collection and analysis
We used standard methodological procedures of Cochrane.
Main results
Our search yielded 3284 records, and of these, we selected 21 reports for fullâtext review. Six studies with 1886 participants met our inclusion criteria, comparing probiotics with placebo. Two studies examined Lactobacillus reuteri DSM, two examined multiâstrain probiotics, one examined Lactobacillus rhamnosus, and one examined Lactobacillus paracasei and Bifidobacterium animalis. Two studies began probiotics during pregnancy and continued administering them to the baby after birth.
We considered the risk of bias for randomisation as low for all six trials; for allocation concealment as low in two studies and unclear in four others. All studies were blinded, and at low risk of attrition and reporting bias.
A randomâeffects metaâanalysis of three studies (1148 participants) found no difference between the groups in relation to occurrence of new cases of colic: risk ratio (RR) 0.46, 95% confidence interval (CI) 0.18 to 1.19; lowâcertainty evidence; I2 = 72%.
A randomâeffects metaâanalysis of all six studies (1851 participants) found no difference between the groups in relation to serious adverse effects (RR 1.02, 95% CI 0.14 to 7.21; lowâcertainty evidence; I2 not calculable (only four serious events for one comparison, two in each group: meconium plug obstruction, patent ductus arteriosus and neonatal hepatitis).
A randomâeffects metaâanalysis of three studies (707 participants) found a mean difference (MD) of â32.57 minutes per day (95% CI â55.60 to â9.54; lowâcertainty evidence; I2 = 93%) in crying time at study end in favour of probiotics.
A subgroup analysis of the most studied agent, Lactobacillus reuteri, showed a reduction of 44.26 minutes in daily crying with a randomâeffects model (95% CI â66.6 to â21.9; I2 = 92%), in favour of probiotics.
Authors' conclusions
There is no clear evidence that probiotics are more effective than placebo at preventing infantile colic; however, daily crying time appeared to reduce with probiotic use compared to placebo. There were no clear differences in adverse effects.
We are limited in our ability to draw conclusions by the certainty of the evidence, which we assessed as being low across all three outcomes, meaning that we are not confident that these results would not change with the addition of further researc
Platelet-Induced Clumping of Plasmodium falciparumâInfected Erythrocytes from Malawian Patients with Cerebral MalariaâPossible Modulation In Vivo by Thrombocytopenia
Platelets may play a role in the pathogenesis of human cerebral malaria (CM), and they have been shown to induce clumping of Plasmodium falciparumâparasitized red blood cells (PRBCs) in vitro. Both thrombocytopenia and platelet-inducedPRBCclumping are associated with severe malaria and, especially, withCM.In the present study, we investigated the occurrence of the clumping phenomenon in patients with CM by isolating and coincubating their plasma and PRBCs ex vivo. Malawian children with CM all had low platelet counts, with the degree of thrombocytopenia directly proportional to the density of parasitemia. Plasma samples obtained from these patients subsequently induced weak PRBC clumping. When the assays were repeated, with the plasma platelet concentrations adjusted to within the physiological range considered to be normal, massive clumping occurred. The results of this study suggest that thrombocytopenia may, through reduction of platelet-mediated clumping of PRBCs, provide a protective mechanism for the host during CM
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