595 research outputs found
Diet breadth of fish communities in Vamanapuram river, Kerala, South India
An understanding of the feeding habits of fish species in natural environment gives clues for selecting the species for aquaculture. It helps in formulating artificial feeds for culturing species under artificial conditions for small scale or large scale aquaculture. The main objective of the present study was to find the food preferences of fish species in different ecological niches such as low land streams, riverine and estuary. Stomachs were cut, food items removed and stored in 4% formalin. Diet breadth was calculated as per the standard methods widely recommended. The diet breadth calculated for the fish assemblages in Vamanapuram River showed that Puntius amphibius has the highest breadth of 6.64. The surface feeding fishes had low diet breadth which ranged from 1.13-1.83. Their main food has been observed to be terrestrial insects. The generalists like Rasbora daniconius and Puntius filamentosus have diet breadth of 3.27 and 4.15, respectively. Whereas fish species found in estuarine habitats showed diet breadth range from 1.00 to 2.82. The fishes present in the upper regions of the river habitat were observed to have low diet breadth than lowland streams. In general, high diet breadth values were observed during February to May. The breadth of Barilius bakeri showed minor variations among the three seasons (1.00 to 1.20). Based on the diet breadth, the majority of the fishes in Vamanapuram River generalists
Status of the ANAIS Dark Matter Project at the Canfranc Underground Laboratory
The ANAIS experiment aims at the confirmation of the DAMA/LIBRA signal. A
detailed analysis of two NaI(Tl) crystals of 12.5 kg each grown by Alpha
Spectra will be shown: effective threshold at 1 keVee is at reach thanks to
outstanding light collection and robust PMT noise filtering protocols and the
measured background is well understood down to 3 keVee, having quantified K, U
and Th content and cosmogenic activation in the crystals. A new detector was
installed in Canfranc in March 2015 together with the two previous modules and
preliminary characterization results will be presented. Finally, the status and
expected sensitivity of the full experiment with 112 kg will be reviewed.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs,
Zaragoza, June 22 to 26, 201
Background model of NaI(Tl) detectors for the ANAIS Dark Matter Project
A thorough understanding of the background sources is mandatory in any
experiment searching for rare events. The ANAIS (Annual Modulation with NaI(Tl)
Scintillators) experiment aims at the confirmation of the DAMA/LIBRA signal at
the Canfranc Underground Laboratory (LSC). Two NaI(Tl) crystals of 12.5 kg each
produced by Alpha Spectra have been taking data since December 2012. The
complete background model of these detectors and more precisely in the region
of interest will be described. Preliminary background analysis of a new 12.5 kg
crystal received at Canfranc in March 2015 will be presented too. Finally, the
power of anticoincidence rejection in the region of interest has been analyzed
in a 4x 5 12.5 kg detector matrix.Comment: Contributed to the 11th Patras Workshop on Axions, WIMPs and WISPs,
Zaragoza, June 22 to 26, 201
Production and relevance of cosmogenic radionuclides in NaI(Tl) crystals
The cosmogenic production of long-lived radioactive isotopes in materials is
an hazard for experiments demanding ultra-low background conditions. Although
NaI(Tl) scintillators have been used in this context for a long time, very few
activation data were available. We present results from two 12.5 kg NaI(Tl)
detectors, developed within the ANAIS project and installed at the Canfranc
Underground Laboratory. The prompt data taking starting made possible a
reliable quantification of production of some I, Te and Na isotopes with
half-lives larger than ten days. Initial activities underground were measured
and then production rates at sea level were estimated following the history of
detectors; a comparison of these rates with calculations using typical cosmic
neutron flux at sea level and a selected description of excitation functions
was also carried out. After including the contribution from the identified
cosmogenic products in the detector background model, we found that the
presence of 3H in the crystal bulk would help to fit much better our background
model and experimental data. We have analyzed the cosmogenic production of 3H
in NaI, and although precise quantification has not been attempted, we can
conclude that it could imply a very relevant contribution to the total
background below 15 keV in NaI detectors.Comment: Proceedings of the Low Radioactivity Techniques 2015 workshop, March
2015, Seattle (US
Analysis of backgrounds for the ANAIS-112 dark matter experiment
The ANAIS (Annual modulation with NaI(Tl) Scintillators) experiment aims at
the confirmation or refutation of theDAMA/LIBRA positive annual modulation
signal in the low energy detection rate, using the same target and technique,
at the Canfranc Underground Laboratory (LSC) in Spain. ANAIS-112, consisting of
nine 12.5 kg NaI(Tl) modules produced by Alpha Spectra Inc. in a 3x3matrix
configuration, is taking data smoothly in "dark matter search" mode since
August, 2017, after a commissioning phase and operation of the first detectors
during the last years in various setups. A large effort has been carried out
withinANAIS to characterize the background of sodium iodide detectors, before
unblinding the data and performing the first annual modulation analysis. Here,
the background models developed for all the nine ANAIS-112 detectors are
presented. Measured spectra from threshold to high energy in different
conditions are well described by the models based on quantified activities
independently estimated following several approaches. In the region from 1 to 6
keVee the measured, efficiency corrected background level is 3.58+-0.02 keV-1
kg-1 day-1; NaI crystal bulk contamination is the dominant background source
being 210Pb, 40K, 22Na and 3H contributions the most relevant ones. This
background level, added to the achieved 1 keVee analysis threshold (thanks to
the outstanding light collection and robust filtering procedures developed),
allow ANAIS-112 to be sensitive to the modulation amplitude measured by
DAMA/LIBRA, and able to explore at three sigma level in 5 years the WIMP
parameter region singled out by this experiment.Comment: Final version for publicatio
'People have started to deliver in the facility these days': a qualitative exploration of factors affecting facility delivery in Ethiopia
Objectives To understand the recent rise in facility deliveries in Ethiopia.
Design A qualitative study.
Setting Four rural communities in two regions of Ethiopia.
Participants 12 narrative, 12 in-depth interviews and four focus group discussions with recently delivered women; and four focus group discussions with each of grandmothers, fathers and community health workers.
Results We found that several interwoven factors led to the increase in facility deliveries, and that respondents reported that the importance of these factors varied over time. The initial catalysts were a saturation of messages around facility delivery, improved accessibility of facilities, the prohibition of traditional birth attendants, and elders having less influence on deciding the place of delivery. Once women started to deliver in facilities, the drivers of the behaviour changed as women had positive experiences. As more women began delivering in facilities, families shared positive experiences of the facilities, leading to others deciding to deliver in a facility.
Conclusion Our findings highlight the need to employ strategies that act at multiple levels, and that both push and pull families to health facilities
Study of scintillation in natural and synthetic quartz and methacrylate
Samples from different materials typically used as optical windows or light
guides in scintillation detectors were studied in a very low background
environment, at the Canfranc Underground Laboratory, searching for
scintillation. A positive result can be confirmed for natural quartz: two
distinct scintillation components have been identified, not being excited by an
external gamma source. Although similar effect has not been observed neither
for synthetic quartz nor for methacrylate, a fast light emission excited by
intense gamma flux is evidenced for all the samples in our measurements. These
results could affect the use of these materials in low energy applications of
scintillation detectors requiring low radioactive background conditions, as
they entail a source of background.Comment: Accepted for publication in Optical Material
Early postnatal home visits: a qualitative study of barriers and facilitators to achieving high coverage
BACKGROUND: Timely interventions in the postnatal period are important for reducing newborn mortality, and early home visits to provide postnatal care are recommended. There has been limited success in achieving timely visits, and a better understanding of the realities of programmes is needed if improvements are to be made. METHODS: We explored barriers and facilitators to timely postnatal visits through 20 qualitative interviews and 16 focus group discussions with families and Health Extension Workers in four Ethiopian sites. RESULTS: All sites reported some inaccessible areas that did not receive visits, but, Health Extension Workers in the sites with more difficult terrain were reported to make more visits that those in the more accessible areas. This suggests that information and work issues can be more important than moderate physical issues. The sites where visits were common had functioning mechanisms for alerting workers to a birth; these were not related to postnatal visits but to families informing Health Extension Workers of labour so they could call an ambulance. In the other sites, families did not know they should alert workers about a delivery, and other alert mechanisms were not functioning well. Competing activities reducing Health Extension Worker availability for visits, but in some areas workers were more organized in their division of their work and this facilitated visits. The main difference between the areas where visits were reported as common or uncommon was the general activity level of the Health Extension Worker. In the sites where workers were active and connected to the community visits occurred more often. CONCLUSIONS: If timely postnatal home visits are to occur, CHWs need realistic catchment areas that reflect their workload. Inaccessible areas may need their own CHW. Good notification systems are essential, families will notify CHWs if they have a clear reasons to do so, and more work is needed on how to ensure notification systems function. Work ethic was a clear influencer on whether home visits occur, studies to date have focused on understanding the motivation of CHWs as a group, more studies on understanding motivation at an individual level are needed
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