55 research outputs found
Role of filtration in managing the risk from Cryptosporidium in commercial swimming pools – a review
Most commercial swimming pools use pressurised filters, typically containing sand media, to remove suspended solids as part of the water treatment process designed to keep water attractive, clean and safe. The accidental release of faecal material by bathers presents a poorly quantified risk to the safety of swimmers using the pool. The water treatment process usually includes a combination of maintaining a residual concentration of an appropriate biocide in the pool together with filtration to physically remove particles, including microbial pathogens, from the water. However, there is uncertainty about the effectiveness of treatment processes in removing all pathogens, and there has been growing concern about the number of reported outbreaks of the gastrointestinal disease cryptosporidiosis, caused by the chlorine-resistant protozoan parasite Cryptosporidium. A number of interacting issues influence the effectiveness of filtration for the removal of Cryptosporidium oocysts from swimming pools. This review explains the mechanisms by which filters remove particles of different sizes (including oocyst-sized particles, typically 4–6 μm), factors that affect the efficiency of particle removal (such as filtration velocity), current recommended management practices, and identifies further work to support the development of a risk-based management approach for the management of waterborne disease outbreaks from swimming pools
Occurrence of Cryptosporidium Oocysts in Leisure Pools in the UK, 2017, and Modelling of Oocyst Contamination Events
Cryptosporidium is a major cause of diarrhoea outbreaks linked to swimming pools, but little is known about the frequency of contamination. The primary aim was to investigate the occurrence and concentration, through sampling and modelling, of Cryptosporidium oocysts in leisure pools. Secondary aims were to compare detections with operational parameters, provide the evidence-base for guidance, and improve sampling capacity and interpretation for public health investigations. Up to 1000 L pool water was sampled during swim sessions once weekly for 10 weeks from 8 August 2017 at six volunteer pools. Oocysts were detected by microscopy in 12/59 (20%) pool water samples, at least once in each pool; 8/12 (66%) detections were in August when bather loads were highest. At three pools, 1 L filter backwash was sampled weekly and oocysts were detected in 2/29 (7%) samples, following detections in pool water. The probabilities of a bather contaminating the pool ranged from 1 in 1000 to over 1 in 10,000. Monte Carlo analysis showed that when high bather numbers caused contamination on over 70% of days, multiple events per day were more likely than single events. In these generally well-managed leisure pools, Cryptosporidium risk related to high bather loads. We conclude that public awareness campaigns for bather hygiene, and reminding pool operators of current guidance for managing faecal accidents, should be ahead of peak swim season
The EuroSTARRS-2001 aircraft campaign of the European Space Agency in support of the SMOS Mission
Ponencia presentada en: III Congreso de la Asociación Española de Climatología “El agua y el clima”, celebrado en Palma de Mallorca del 16 al 19 de junio de 2002.This work was carried out in the
framework of the ESA-ESTEC contract no: 15949/02/NL/SF, and the Spanish National Space
Research Programme Project no: PNE-009/2001-C-03
The ionising photon production efficiency at z~6 for a sample of bright Lyman-alpha emitters using JEMS and MUSE
We study the ionising photon production efficiency at the end of the Epoch of
Reionisation () for a sample of 35 bright Lyman-
emitters, this quantity is crucial to infer the ionising photon budget of the
Universe. These objects were selected to have reliable spectroscopic redshifts,
assigned based on the profile of their Lyman- emission line, detected
in the MUSE deep fields. We exploit medium-band observations from the JWST
extragalactic medium band survey (JEMS) to find the flux excess corresponding
to the redshifted \ha\ emission line. We estimate the UV luminosity by fitting
the full JEMS photometry, along with several HST photometric points, with
\texttt{Prospector}. We find a median ultra-violet continuum slope of for the sample, indicating young stellar populations
with little-to-no dust attenuation. Supported by this, we derive
with no dust attenuation and find a median value of
log. If we
perform dust attenuation corrections and assume a Calzetti attenuation law, our
values are lowered by dex. Our results suggest Lyman-
emitters at the Epoch of Reionisation have enhanced compared to
previous estimations from literature, in particular, when compared to the
non-Lyman- emitting population. This initial study provides a promising
outlook on the characterisation of ionising photon production in the early
Universe. In the future, a more extensive study will be performed on the entire
dataset provided by the JWST Advanced Deep Extragalactic Survey (JADES). Thus,
for the first time, allowing us toComment: 11 pages, 5 figures in main paper. 10 pages, 30 figures in appendix.
Submitted to MNRA
JWST-JADES. Possible Population III signatures at z=10.6 in the halo of GN-z11
Finding the first generation of stars formed out of pristine gas in the early
Universe, known as Population III (PopIII) stars, is one of the most important
goals of modern astrophysics. Recent models suggest that PopIII stars may form
in pockets of pristine gas in the halo of more evolved galaxies. Here we
present NIRSpec-IFU and NIRSpec-MSA observations of the region around GN-z11,
an exceptionally luminous galaxy at , which reveal a 5
detection of a feature consistent with being HeII1640 emission at the
redshift of GN-z11. The very high equivalent width of the putative HeII
emission in this clump (170 A), and the lack of metal lines, can be explained
in terms of photoionisation by PopIII stars, while photoionisation by PopII
stars is inconsistent with the data. It would also indicate that the putative
PopIII stars likely have a top-heavy initial mass function (IMF), with an upper
cutoff reaching at least 500 M. The PopIII bolometric luminosity
inferred from the HeII line would be , which
(with a top-heavy IMF) would imply a total stellar mass formed in the burst of
. We find that photoionisation by the Active
Galactic Nucleus (AGN) in GN-z11 cannot account for the HeII luminosity
observed in the clump, but can potentially be responsible for additional HeII
emission observed closer to GN-z11. We also consider the possibility of in-situ
photoionisation by an accreting Direct Collapse Black Hole (DCBH) hosted by the
HeII clump; we find that this scenario is less favoured, but it remains a
possible alternative interpretation. We also report the detection of a
Ly halo stemming out of GN-z11 and extending out to 2 kpc, as
well as resolved, funnel-shaped CIII] emission, likely tracing the ionisation
cone of the AGN.Comment: Submitted to A&A, 13 pages, 8 figures; some typos corrected and some
minor additional information added to match submitted versio
JADES: The production and escape of ionizing photons from faint Lyman-alpha emitters in the epoch of reionization
We present the properties of 17 faint Ly emitting galaxies (LAEs) at
from the JWST Advanced Deep Extragalactic Survey (JADES) in the Hubble
Ultra Deep Field/GOODS-S. These LAEs span a redshift range
and a UV magnitude range to , with the Ly
equivalent width (EW) in the range \AA. The detection of other
rest-optical emission lines in the spectra of these LAEs enables the
determination of accurate systemic redshifts and Ly{\alpha} velocity offsets,
as well as the physical and chemical composition of their stars and
interstellar media. These faint LAEs are consistent with metal-poor systems
with high ionization parameters, similar to the general galaxy population at
. We measured an average ionizing photon production efficiency,
log(\xi_\rm{ion}/erg Hz) across our LAEs, which does
not evolve strongly with redshift. We report an anti-correlation between the
Ly escape fraction (f_\rm{esc}) and the velocity offset from systemic
redshift, consistent with model expectations. We further find that the strength
and velocity offset of Ly are neither correlated with galaxy
spectroscopic properties nor with \xi_\rm{ion}. We find a decrease in
f_\rm{esc}(Ly) with redshift, indicative of decreasing sizes of
ionized bubbles around LAEs at high redshifts. We used a range of galaxy
properties to predict Lyman continuum f_\rm{esc} for our LAEs, finding that
the ionizing photon output into the intergalactic medium remains roughly
constant across the observed Ly EW, showing a mild increase at fainter
M and at higher redshifts. We derived correlations between the ionizing
photon output from LAEs and , Ly EW and redshifts, which can be
used to constrain the ionizing photon contribution of LAEs at towards
cosmic reionization.Comment: Accepted for publication in A&A. 24 pages, 13 figures, spectra
presented in the appendix. This updated version includes the addition of one
more LAE to the sample, ID 004296 at z=6.71
Inside the bubble: exploring the environments of reionisation-era Lyman-α emitting galaxies with JADES and FRESCO⋆
© 2024 The Author(s). Published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/We present a study of the environments of 17 Lyman-α emitting galaxies (LAEs) in the reionisation-era (5.8 5%) observed in our sample of LAEs, suggesting the presence of ionised hydrogen along the line of sight towards at least eight out of 17 LAEs. We find minimum physical 'bubble'sizes of the order of R ion ∼ 0.1- 1pMpc are required in a patchy reionisation scenario where ionised bubbles containing the LAEs are embedded in a fully neutral IGM. Around half of the LAEs in our sample are found to coincide with large-scale galaxy overdensities seen in FRESCO at z ∼ 5.8- 5.9 and z ∼ 7.3, suggesting Lyman-α transmission is strongly enhanced in such overdense regions, and underlining the importance of LAEs as tracers of the first large-scale ionised bubbles. Considering only spectroscopically confirmed galaxies, we find our sample of UV-faint LAEs (M UV ≳ -20mag) and their direct neighbours are generally not able to produce the required ionised regions based on the Lyman-α transmission properties, suggesting lower-luminosity sources likely play an important role in carving out these bubbles. These observations demonstrate the combined power of JWST multi-object and slitless spectroscopy in acquiring a unique view of the early Universe during cosmic reionisation via the most distant LAEs.Peer reviewe
The Star-forming and Ionizing Properties of Dwarf z~6-9 Galaxies in JADES: Insights on Bursty Star Formation and Ionized Bubble Growth
Reionization is thought to be driven by faint star-forming galaxies, but
characterizing this population in detail has long remained very challenging.
Here we utilize deep nine-band NIRCam imaging from JADES to study the
star-forming and ionizing properties of 756 galaxies, including
hundreds of very UV-faint objects (). The faintest
() galaxies in our sample typically have stellar masses of
and young light-weighted ages (50
Myr), though some show strong Balmer breaks implying much older ages (500
Myr). We find no evidence for extremely massive galaxies (
) in our sample. We infer a strong (factor 2) decline in the
typical [OIII]H EWs towards very faint galaxies, yet a
weak UV luminosity dependence on the H EWs at . We demonstrate
that these EW trends can be explained if fainter galaxies have systematically
lower metallicities as well as more recently-declining star formation histories
relative to the most UV-luminous galaxies in our sample. Our data provide
evidence that the brightest galaxies are frequently experiencing a recent
strong upturn in SFR. We also discuss how the EW trends may be influenced by a
strong correlation between and Lyman continuum escape fraction.
This alternative explanation has dramatically different implications for the
contribution of galaxies along the luminosity function to cosmic reionization,
highlighting the need for deep spectroscopic follow-up. Finally, we quantify
the photometric overdensities around two strong Ly emitters in
the JADES footprint. One Ly emitter lies close to a strong photometric
overdensity while the other shows no significant nearby overdensity, perhaps
implying that not all strong Ly emitters reside in large ionized
bubbles.Comment: 29 pages, 16 figures. Submitted to MNRAS. Comments welcom
The effectiveness, acceptability and cost-effectiveness of psychosocial interventions for maltreated children and adolescents: an evidence synthesis.
BACKGROUND: Child maltreatment is a substantial social problem that affects large numbers of children and young people in the UK, resulting in a range of significant short- and long-term psychosocial problems. OBJECTIVES: To synthesise evidence of the effectiveness, cost-effectiveness and acceptability of interventions addressing the adverse consequences of child maltreatment. STUDY DESIGN: For effectiveness, we included any controlled study. Other study designs were considered for economic decision modelling. For acceptability, we included any study that asked participants for their views. PARTICIPANTS: Children and young people up to 24 years 11 months, who had experienced maltreatment before the age of 17 years 11 months. INTERVENTIONS: Any psychosocial intervention provided in any setting aiming to address the consequences of maltreatment. MAIN OUTCOME MEASURES: Psychological distress [particularly post-traumatic stress disorder (PTSD), depression and anxiety, and self-harm], behaviour, social functioning, quality of life and acceptability. METHODS: Young Persons and Professional Advisory Groups guided the project, which was conducted in accordance with Cochrane Collaboration and NHS Centre for Reviews and Dissemination guidance. Departures from the published protocol were recorded and explained. Meta-analyses and cost-effectiveness analyses of available data were undertaken where possible. RESULTS: We identified 198 effectiveness studies (including 62 randomised trials); six economic evaluations (five using trial data and one decision-analytic model); and 73 studies investigating treatment acceptability. Pooled data on cognitive-behavioural therapy (CBT) for sexual abuse suggested post-treatment reductions in PTSD [standardised mean difference (SMD) -0.44 (95% CI -4.43 to -1.53)], depression [mean difference -2.83 (95% CI -4.53 to -1.13)] and anxiety [SMD -0.23 (95% CI -0.03 to -0.42)]. No differences were observed for post-treatment sexualised behaviour, externalising behaviour, behaviour management skills of parents, or parental support to the child. Findings from attachment-focused interventions suggested improvements in secure attachment [odds ratio 0.14 (95% CI 0.03 to 0.70)] and reductions in disorganised behaviour [SMD 0.23 (95% CI 0.13 to 0.42)], but no differences in avoidant attachment or externalising behaviour. Few studies addressed the role of caregivers, or the impact of the therapist-child relationship. Economic evaluations suffered methodological limitations and provided conflicting results. As a result, decision-analytic modelling was not possible, but cost-effectiveness analysis using effectiveness data from meta-analyses was undertaken for the most promising intervention: CBT for sexual abuse. Analyses of the cost-effectiveness of CBT were limited by the lack of cost data beyond the cost of CBT itself. CONCLUSIONS: It is not possible to draw firm conclusions about which interventions are effective for children with different maltreatment profiles, which are of no benefit or are harmful, and which factors encourage people to seek therapy, accept the offer of therapy and actively engage with therapy. Little is known about the cost-effectiveness of alternative interventions. LIMITATIONS: Studies were largely conducted outside the UK. The heterogeneity of outcomes and measures seriously impacted on the ability to conduct meta-analyses. FUTURE WORK: Studies are needed that assess the effectiveness of interventions within a UK context, which address the wider effects of maltreatment, as well as specific clinical outcomes. STUDY REGISTRATION: This study is registered as PROSPERO CRD42013003889. FUNDING: The National Institute for Health Research Health Technology Assessment programme
The Cosmos in its Infancy: JADES Galaxy Candidates at z > 8 in GOODS-S and GOODS-N
We present a catalog of 717 candidate galaxies at selected from 125
square arcminutes of NIRCam imaging as part of the JWST Advanced Deep
Extragalactic Survey (JADES). We combine the full JADES imaging dataset with
data from the JEMS and FRESCO JWST surveys along with extremely deep existing
observations from HST/ACS for a final filter set that includes fifteen
JWST/NIRCam filters and five HST/ACS filters. The high-redshift galaxy
candidates were selected from their estimated photometric redshifts calculated
using a template fitting approach, followed by visual inspection from seven
independent reviewers. We explore these candidates in detail, highlighting
interesting resolved or extended sources, sources with very red long-wavelength
slopes, and our highest redshift candidates, which extend to .
We also investigate potential contamination by stellar objects, and do not find
strong evidence from SED fitting that these faint high-redshift galaxy
candidates are low-mass stars. Over 93\% of the sources are newly identified
from our deep JADES imaging, including 31 new galaxy candidates at . Using 42 sources in our sample with measured spectroscopic redshifts from
NIRSpec and FRESCO, we find excellent agreement to our photometric redshift
estimates, with no catastrophic outliers and an average difference of . These sources comprise one of the
most robust samples for probing the early buildup of galaxies within the first
few hundred million years of the Universe's history.Comment: v2: 40 pages, 18 figures, submitted to AAS Journals, online data
catalog (JADES Deep only) found at https://doi.org/10.5281/zenodo.809252
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