754 research outputs found
Why latrines are not used : communities' perceptions and practices regarding latrines in a Taenia solium endemic rural area in Eastern Zambia
Taenia solium cysticercosis is a neglected parasitic zoonosis occurring in many developing countries. Socio-cultural determinants related to its control remain unclear. Studies in Africa have shown that the underuse of sanitary facilities and the widespread occurrence of free-roaming pigs are the major risk factors for porcine cysticercosis. The study objective was to assess the communities' perceptions, practices and knowledge regarding latrines in a T. solium endemic rural area in Eastern Zambia inhabited by the Nsenga ethno-linguistic group, and to identify possible barriers to their construction and use. A total of 21 focus group discussions on latrine use were organized separately with men, women and children, in seven villages of the Petauke district. The themes covered were related to perceived latrine availability (absence-presence, building obstacles) and perceived latrine use (defecation practices, latrine management, socio-cultural constraints). The findings reveal that latrines were not constructed in every household because of the convenient use of existing latrines in the neighborhood. Latrines were perceived to contribute to good hygiene mainly because they prevent pigs from eating human feces. Men expressed reluctance to abandon the open-air defecation practice mainly because of toilet-associated taboos with in-laws and grown-up children of the opposite gender. When reviewing conceptual frameworks of people's approach to sanitation, we found that seeking privacy and taboos hindering latrine use and construction were mainly explained in our study area by the fact that the Nsenga observe a traditionally matrilineal descent. These findings indicate that in this local context latrine promotion messages should not only focus on health benefits in general. Since only men were responsible for building latrines and mostly men preferred open defecation, sanitation programs should also be directed to men and address related sanitary taboos in order to be effective
Accounting for the foreground contribution to the dust emission towards Kepler's supernova remnant
âThe definitive version is available at www3.interscience.wiley.com '. Copyright Royal Astronomical Society. DOI: 10.1111/j.1365-2966.2009.15061.xWhether or not supernovae contribute significantly to the overall dust budget is a controversial subject. Submillimetre (sub-mm) observations, sensitive to cold dust, have shown an excess at 450 and 850 ÎŒm in young remnants Cassiopeia A (Cas A) and Kepler. Some of the sub-mm emission from Cas A has been shown to be contaminated by unrelated material along the line of sight. In this paper, we explore the emission from material towards Kepler using sub-mm continuum imaging and spectroscopic observations of atomic and molecular gas, via H i, 12CO(J= 2â1) and 13CO(J= 2â1). We detect weak CO emission (peak T*A = 0.2â1 K, 1â2 km sâ1 full width at half-maximum) from diffuse, optically thin gas at the locations of some of the sub-mm clumps. The contribution to the sub-mm emission from foreground molecular and atomic clouds is negligible. The revised dust mass for Kepler's remnant is 0.1â1.2 Mâ , about half of the quoted values in the original study by Morgan et al., but still sufficient to explain the origin of dust at high redshifts.Peer reviewe
The SCUBA Bright Quasar Survey II: unveiling the quasar epoch at submillimetre wavelengths
We present results of the first systematic search for submillimetre continuum emission from z=2, radio-quiet, optically-luminous quasars, using the SCUBA/JCMT. We have observed a homogeneous sample of 57 quasars in the redshift range 1.54) redshift. The target sensitivity of the survey (3sigma=10mJy at 850um) was chosen to enable efficient identification of bright submm sources, suitable for detailed follow-up. 9 targets are detected, with fluxes in the range 7-17mJy. Although there is a suggestion of variation of submm detectability between z=2 and z=4, this is consistent with the K-correction of a characteristic far-infrared spectrum. Additionally, the weighted mean fluxes of non-detections at z=2 and z>4 are comparable
NPK detection spectroscopy on non-agriculture soil
Soil is a medium for plant roots to grow, absorb water and necessary solutes for growth. Soil macronutrient testing is helpful for determining the nutrients content in soil before applying fertilizer for quality and process controls of agricultural produce and soil fertility. Spectroscopy is an emerging technology which is rapid and simple has been widely used in agricultural and food analysis processes. The capability of spectroscopy to characterize material from the transmission or absorbance has been used in this paper to measure nitrogen (N), phosphorus (P) and potassium (K) content in non-agriculture soil. The paper details preliminary characterization of soil spectroscopy with a Deuterium-Halogen light source and Ocean Optic spectrometer to measure the absorbance level of the macronutrients. The extracted nutrients were mixed with the colour reagent and specific colored solution was developed. Two soil samples have been employed for the experimental characterization, which are mud flood and kaolin. The result shows that high absorbance level of N at 450 nm in wavelength, P at 750 nm for both samples. The absorbance level of K was measured high at 500nm for mud flood and 450nm for kaolin. In addition, the tested macronutrients give similar wavelength of peak absorbance level at 970 nm for both samples. For future works, the optical measurements will be implemented using visible and near infrared LED and the photodetector in order to replace the spectrometer usage for soil spectroscopy. This would lead to achieve the primary objective of this research in developing a simple and low cost spectroscopy uses light-emitting diode (LED)
The Radio-to-Submm Spectral Index as a Redshift Indicator
We present models of the 1.4 GHz to 350 GHz spectral index, alpha(350/1.4),
for starburst galaxies as a function of redshift. The models include a
semi-analytic formulation, based on the well quantified radio-to-far infrared
correlation for low redshift star forming galaxies, and an empirical
formulation, based on the observed spectrum of the starburst galaxies M82 and
Arp 220. We compare the models to the observed values of alpha(350/1.4) for
starburst galaxies at low and high redshift. We find reasonable agreement
between the models and the observations, and in particular, that an observed
spectral index of alpha(350/1.4) > +0.5 indicates that the target source is
likely to be at high redshift, z > 1. The evolution of alpha(350/1.4) with
redshift is mainly due to the very steep rise in the Raleigh-Jeans portion of
the thermal dust spectrum shifting into the 350 GHz band with increasing
redshift. We also discuss situations where this relationship could be violated.
We then apply our models to examine the putative identifications of submm
sources in the Hubble Deep Field, and conclude that the submm sources reported
by Hughes et al. are likely to be at high redshifts, z > 1.5.Comment: standard LATEX file plus 1 postscript figure. Added references and
revised figure. second figure revision. Final Proof version. to appear in
Astrophysical Journal Letter
A Search for Dense Molecular Gas in High Redshift Infrared-Luminous Galaxies
We present a search for HCN emission from four high redshift far infrared
(IR) luminous galaxies. Current data and models suggest that these high IR
luminous galaxies represent a major starburst phase in the formation of
spheroidal galaxies, although many of the sources also host luminous active
galactic nuclei (AGN), such that a contribution to the dust heating by the AGN
cannot be precluded. HCN emission is a star formation indicator, tracing dense
molecular hydrogen gas within star-forming molecular clouds (n(H) cm). HCN luminosity is linearly correlated with IR luminosity for
low redshift galaxies, unlike CO emission which can also trace gas at much
lower density. We report a marginal detection of HCN (1-0) emission from the
QSO J1409+5628, with a velocity integrated line luminosity of
K km s pc, while we obtain
3 upper limits to the HCN luminosity of the QSO J0751+2716 of
K km s pc, K km s pc for the starburst galaxy
J1401+0252, and K km s pc for the QSO J1148+5251. We compare the HCN data on these sources, plus three
other high- IR luminous galaxies, to observations of lower redshift
star-forming galaxies. The values of the HCN/far-IR luminosity ratios (or
limits) for all the high sources are within the scatter of the relationship
between HCN and far-IR emission for low star-forming galaxies (truncated).Comment: aastex format, 4 figures. to appear in the Astrophysical Journal;
Revised lens magnification estimate for 1401+025
Fire and Fish Dynamics in a Changing Climate: Broad- and Local-Scale Effects of Fire-Induced Water Temperature Changes on Native and Nonnative Fish Communities
Fire is a key natural disturbance that affects the distribution and abundance of native fishes in the Rocky Mountain West. In the absence of migratory individuals from undisturbed portions of a watershed, persistence of native fish populations depends on the conditions of the post-fire stream environment. Stream temperatures typically warm after fire, and remain elevated until riparian vegetation recovers. An additional threat to native species is that nonnative fishes have invaded many waters, and these species tolerate or prefer warmer water temperatures. Thus, forecasting the long-term effects of fire on native fish populations requires an understanding of fire dynamics (size, distribution, frequency, and severity), the extent and location of changes in riparian forest structure and time to recovery, changes in stream temperatures associated with these forest changes, and how native and nonnative fish respond to changes in water temperature. To perform spatially explicit simulation modeling that examined the relations among fire disturbance, stream temperature, and fish communities, we upgraded and then linked the fire-forest succession model FireBGCv2 to a stream temperature model to project changes in water temperature in the East Fork Bitterroot River basin in Montana under an array of climate and fire management scenarios. Model projections indicated that although climate led to increases in fire severity, frequency, or size, water temperature increases at the basin scale were primarily a consequence of climate-driven atmospheric warming rather than changes in fire regime. Consequently, variation in fire managementâfuel treatment or fire suppressionâhad little effect at this scale, but assumed greater importance at the scale of riparian stands. By revisiting a large number of previously sampled sites in the East Fork Bitterroot River basin in Montana, we evaluated whether bull trout persistence and other native and nonnative fish distributions were related to temperature changes associated with fire and recent climatic trends. Although fires were related to marked increases in summer water temperatures, these changes had a positive effect (westslope cutthroat trout) or a negligible effect (bull trout) on the abundance and distribution of native fish species, whereas the abundance of nonnative brook trout markedly declined in some instances. Fire-related changes in factors other than the thermal regime may have contributed to these patterns. In contrast, at the scale of the entire basin we observed an upward-directed contraction in the distribution of bull trout that was unrelated to fire. We concluded that this may be a response to temperature increases related to climate change
Fire and Fish Dynamics in a Changing Climate: Broad- and Local-Scale Effects of Fire-Induced Water Temperature Changes on Native and Nonnative Fish Communities
Fire is a key natural disturbance that affects the distribution and abundance of native fishes in the Rocky Mountain West. In the absence of migratory individuals from undisturbed portions of a watershed, persistence of native fish populations depends on the conditions of the post-fire stream environment. Stream temperatures typically warm after fire, and remain elevated until riparian vegetation recovers. An additional threat to native species is that nonnative fishes have invaded many waters, and these species tolerate or prefer warmer water temperatures. Thus, forecasting the long-term effects of fire on native fish populations requires an understanding of fire dynamics (size, distribution, frequency, and severity), the extent and location of changes in riparian forest structure and time to recovery, changes in stream temperatures associated with these forest changes, and how native and nonnative fish respond to changes in water temperature. To perform spatially explicit simulation modeling that examined the relations among fire disturbance, stream temperature, and fish communities, we upgraded and then linked the fire-forest succession model FireBGCv2 to a stream temperature model to project changes in water temperature in the East Fork Bitterroot River basin in Montana under an array of climate and fire management scenarios. Model projections indicated that although climate led to increases in fire severity, frequency, or size, water temperature increases at the basin scale were primarily a consequence of climate-driven atmospheric warming rather than changes in fire regime. Consequently, variation in fire managementâfuel treatment or fire suppressionâhad little effect at this scale, but assumed greater importance at the scale of riparian stands. By revisiting a large number of previously sampled sites in the East Fork Bitterroot River basin in Montana, we evaluated whether bull trout persistence and other native and nonnative fish distributions were related to temperature changes associated with fire and recent climatic trends. Although fires were related to marked increases in summer water temperatures, these changes had a positive effect (westslope cutthroat trout) or a negligible effect (bull trout) on the abundance and distribution of native fish species, whereas the abundance of nonnative brook trout markedly declined in some instances. Fire-related changes in factors other than the thermal regime may have contributed to these patterns. In contrast, at the scale of the entire basin we observed an upward-directed contraction in the distribution of bull trout that was unrelated to fire. We concluded that this may be a response to temperature increases related to climate change
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