2,564 research outputs found
Effectiveness of Two Water Conservation Policies: An Integrated Modeling Approach
Agriculture in the Texas High Plains depends entirely on the Ogallala Aquifer. Texas enacted water conservation legislation to address declining reserves in the aquifer. We developed an integrated regional water policy model that links a hydrology model with an economic optimization model to estimate policy impacts with respect to economic cost and water conservation. Testing the effectiveness of two policies, a groundwater extraction tax and extraction quotas, we observe that neither significantly inhibits groundwater use. Although both policies conserve similar amounts of groundwater, the regional cost of the tax policy to agriculture is more than the quota policy.integrated regional water policy model, Texas High Plains, water conservation policy, hydrology model, economic optimization model, Ogallala Aquifer, tax policy, quota policy, Agribusiness, Community/Rural/Urban Development, Food Security and Poverty, Land Economics/Use, Political Economy, Q30, Q31, Q38,
Priority Effects Among Young-of-the-Year Fish: Reduced Growth of Bluegill Sunfish (Lepomis macrochirus) Caused by Yellow Perch (Perca flavescens)?
1. When available, Daphnia spp. are often preferred by age-0 yellow perch and bluegill sunfish because of energetic profitability. We hypothesised that predation by age-0 yellow perch could lead to a midsummer decline (MSD) of Daphnia spp. and that priority effects may favour yellow perch because they hatch before bluegill, allowing them to capitalise on Daphnia spp. prior to bluegill emergence. 2. Data were collected from 2004 to 2010 in Pelican Lake, Nebraska, U.S.A. The lake experienced a prolonged MSD in all but 1 year (2005), generally occurring within the first 2 weeks of June except in 2008 and 2010 when it occurred at the end of June. MSD timing is not solely related to seasonal patterns of age-0 yellow perch consumption. Nevertheless, when Daphnia spp. biomass was low during 2004 and 2006–2010 (\u3c4 mg wet weight L)1 ), predation by age-0 yellow perch seems to have suppressed Daphnia spp. biomass (i.e. \u3c1.0 mg wet weight L)1 ). The exception was 2005 when age-0 yellow perch were absent. 3. Growth of age-0 bluegill was significantly faster in 2005, when Daphnia spp. were available in greater densities (\u3e4 mg wet weight L)1 ) compared with the other years (\u3c0.2 mg wet weight L)1 ). 4. We conclude that age-0 yellow perch are capable of reducing Daphnia biomass prior to the arrival of age-0 bluegill, ultimately slowing bluegill growth. Thus, priority effects favour age-0 yellow perch when competing with age-0 bluegill for Daphnia. However, these effects may be minimised if there is a shorter time between hatching of the two species, higher Daphnia spp. densities or lower age-0 yellow perch densities
Priority Effects Among Young-of-the-year Fish: Reduced Growth of Bluegill Sunfish (Lepomis macrochirus) Caused by Yellow Perch (Perca flavescens)?
1. When available, Daphnia spp. are often preferred by age-0 yellow perch and bluegill sunfish because of energetic profitability. We hypothesised that predation by age-0 yellow perch could lead to a midsummer decline (MSD) of Daphnia spp. and that priority effects may favour yellow perch because they hatch before bluegill, allowing them to capitalise on Daphnia spp. prior to bluegill emergence.
2. Data were collected from 2004 to 2010 in Pelican Lake, Nebraska, U.S.A. The lake experienced a prolonged MSD in all but 1 year (2005), generally occurring within the first 2 weeks of June except in 2008 and 2010 when it occurred at the end of June. MSD timing is not solely related to seasonal patterns of age-0 yellow perch consumption. Nevertheless, when Daphnia spp. biomass was low during 2004 and 2006–2010 (\u3c4 mg wet weight L)1), predation by age-0 yellow perch seems to have suppressed Daphnia spp. biomass (i.e. \u3c1.0 mg wet weight L)1). The exception was 2005 when age-0 yellow perch were absent.
3. Growth of age-0 bluegill was significantly faster in 2005, when Daphnia spp. were available in greater densities (\u3e4 mg wet weight L)1) compared with the other years (\u3c0.2 mg wet weight L)1).
4. We conclude that age-0 yellow perch are capable of reducing Daphnia biomass prior to the arrival of age-0 bluegill, ultimately slowing bluegill growth. Thus, priority effects favour age-0 yellow perch when competing with age-0 bluegill for Daphnia. However, these effects may be minimised if there is a shorter time between hatching of the two species, higher Daphnia spp. densities or lower age-0 yellow perch densities
Evidence against equimolarity of large repeat arrangements and a predominant master circle structure of the mitochondrial genome from a monkeyflower (\u3ci\u3eMimulus guttatus\u3c/i\u3e) lineage with cryptic CMS
Despite intense investigation for over 25 years, the in vivo structure of plant mitochondrial genomes remains uncertain. Mapping studies and genome sequencing generally produce large circular chromosomes, whereas electrophoretic and microscopic studies typically reveal linear and multi-branched molecules. To more fully assess the structure of plant mitochondrial genomes, the complete sequence of the monkeyflower (Mimulus guttatus DC. line IM62) mtDNA was constructed from a large (35 kb) paired-end shotgun sequencing library to a high depth of coverage (~30x). The complete genome maps as a 525,671 bp circular molecule and exhibits a fairly conventional set of features including 62 genes (encoding 35 proteins, 24 tRNAs, 3 rRNAs), 22 introns, 3 large repeats (2.7, 9.6, 29 kb), and 96 small repeats (40–293 bp). Most paired-end reads (71%) mapped to the consensus sequence at the expected distance and orientation across the entire genome, validating the accuracy of assembly. Another 10% of reads provided clear evidence of alternative genomic conformations due to apparent rearrangements across large repeats. Quantitative assessment of these repeat-spanning read pairs revealed that all large repeat arrangements are present at appreciable frequencies in vivo, although not always in equimolar amounts. The observed stoichiometric differences for some arrangements are inconsistent with a predominant master circular structure for the mitochondrial genome of M. guttatus IM62. Finally, because IM62 contains a cryptic cytoplasmic male-sterility (CMS) system, an in silico search for potential CMS genes was undertaken. The three chimeric ORFs identified in this study, in addition to the previously identified ORFs upstream of the nad6 gene, are the most likely CMS candidate genes in this line.
Includes Supplementary Information
Evidence against equimolarity of large repeat arrangements and a predominant master circle structure of the mitochondrial genome from a monkeyflower (\u3ci\u3eMimulus guttatus\u3c/i\u3e) lineage with cryptic CMS
Despite intense investigation for over 25 years, the in vivo structure of plant mitochondrial genomes remains uncertain. Mapping studies and genome sequencing generally produce large circular chromosomes, whereas electrophoretic and microscopic studies typically reveal linear and multi-branched molecules. To more fully assess the structure of plant mitochondrial genomes, the complete sequence of the monkeyflower (Mimulus guttatus DC. line IM62) mtDNA was constructed from a large (35 kb) paired-end shotgun sequencing library to a high depth of coverage (~30x). The complete genome maps as a 525,671 bp circular molecule and exhibits a fairly conventional set of features including 62 genes (encoding 35 proteins, 24 tRNAs, 3 rRNAs), 22 introns, 3 large repeats (2.7, 9.6, 29 kb), and 96 small repeats (40–293 bp). Most paired-end reads (71%) mapped to the consensus sequence at the expected distance and orientation across the entire genome, validating the accuracy of assembly. Another 10% of reads provided clear evidence of alternative genomic conformations due to apparent rearrangements across large repeats. Quantitative assessment of these repeat-spanning read pairs revealed that all large repeat arrangements are present at appreciable frequencies in vivo, although not always in equimolar amounts. The observed stoichiometric differences for some arrangements are inconsistent with a predominant master circular structure for the mitochondrial genome of M. guttatus IM62. Finally, because IM62 contains a cryptic cytoplasmic male-sterility (CMS) system, an in silico search for potential CMS genes was undertaken. The three chimeric ORFs identified in this study, in addition to the previously identified ORFs upstream of the nad6 gene, are the most likely CMS candidate genes in this line.
Includes Supplementary Information
Gender Differences in Perception and Care-seeking for Illness of Newborns in Rural Uttar Pradesh, India
Although gender-based health disparities are prevalent in India, very little data are available on care-seeking patterns for newborns. In total, 255 mothers were prospectively interviewed about their perceptions and action surrounding the health of their newborns in rural Uttar Pradesh, India. Perception of illness was significantly lower in incidence (adjusted odds ratio=0.56, 95% confidence interval 0.33-0.94) among households with female versus male newborns. While the overall use of healthcare providers was similar across gender, the average expenditure for healthcare during the neonatal period was nearly four-fold higher in households with males (Rs 243.3±537.2) compared to females (Rs 65.7±100.7) (p=0.07). Households with female newborns used cheaper public care providers whereas those with males preferred to use private unqualified providers perceived to deliver more satisfactory care. These results suggest that, during the neonatal period, care-seeking for girls is neglected compared to boys, laying a foundation for programmes and further research to address gender differences in neonatal health in India
Gender Differences in Perception and Care-seeking for Illness of Newborns in Rural Uttar Pradesh, India
Although gender-based health disparities are prevalent in India, very
little data are available on care-seeking patterns for newborns. In
total, 255 mothers were prospectively interviewed about their
perceptions and action surrounding the health of their newborns in
rural Uttar Pradesh, India. Perception of illness was significantly
lower in incidence (adjusted odds ratio=0.56, 95% confidence interval
0.33-0.94) among households with female versus male newborns. While the
overall use of healthcare providers was similar across gender, the
average expenditure for healthcare during the neonatal period was
nearly four-fold higher in households with males (Rs 243.3\ub1537.2)
compared to females (Rs 65.7\ub1100.7) (p=0.07). Households with
female newborns used cheaper public care providers whereas those with
males preferred to use private unqualified providers perceived to
deliver more satisfactory care. These results suggest that, during the
neonatal period, care-seeking for girls is neglected compared to boys,
laying a foundation for programmes and further research to address
gender differences in neonatal health in India
Does lumbar spinal degeneration begin with the anterior structures? A study of the observed epidemiology in a community-based population
<p>Abstract</p> <p>Background-</p> <p>Prior studies that have concluded that disk degeneration uniformly precedes facet degeneration have been based on convenience samples of individuals with low back pain. We conducted a study to examine whether the view that spinal degeneration begins with the anterior spinal structures is supported by epidemiologic observations of degeneration in a community-based population.</p> <p>Methods-</p> <p>361 participants from the Framingham Heart Study were included in this study. The prevalences of anterior vertebral structure degeneration (disk height loss) and posterior vertebral structure degeneration (facet joint osteoarthritis) were characterized by CT imaging. The cohort was divided into the structural subgroups of participants with 1) no degeneration, 2) isolated anterior degeneration (without posterior degeneration), 3) combined anterior and posterior degeneration, and 4) isolated posterior degeneration (without anterior structure degeneration). We determined the prevalence of each degeneration pattern by age group < 45, 45-54, 55-64, ≥65. In multivariate analyses we examined the association between disk height loss and the response variable of facet joint osteoarthritis, while adjusting for age, sex, BMI, and smoking.</p> <p>Results-</p> <p>As the prevalence of the no degeneration and isolated anterior degeneration patterns decreased with increasing age group, the prevalence of the combined anterior/posterior degeneration pattern increased. 22% of individuals demonstrated isolated posterior degeneration, without an increase in prevalence by age group. Isolated posterior degeneration was most common at the L5-S1 and L4-L5 spinal levels. In multivariate analyses, disk height loss was independently associated with facet joint osteoarthritis, as were increased age (years), female sex, and increased BMI (kg/m<sup>2</sup>), but not smoking.</p> <p>Conclusions-</p> <p>The observed epidemiology of lumbar spinal degeneration in the community-based population is consistent with an ordered progression beginning in the anterior structures, for the majority of individuals. However, some individuals demonstrate atypical patterns of degeneration, beginning in the posterior joints. Increased age and BMI, and female sex may be related to the occurrence of isolated posterior degeneration in these individuals.</p
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Vertical profiles of light absorption and scattering associated with black carbon particle fractions in the springtime Arctic above 79â—¦ N
Despite the potential importance of black carbon (BC) for radiative forcing of the Arctic atmosphere, ver- tically resolved measurements of the particle light scatter- ing coefficient (σsp ) and light absorption coefficient (σap ) in the springtime Arctic atmosphere are infrequent, espe- cially measurements at latitudes at or above 80◦ N. Here, re- lationships among vertically distributed aerosol optical prop- erties (σap, σsp and single scattering albedo or SSA), par- ticle microphysics and particle chemistry are examined for a region of the Canadian archipelago between 79.9 and 83.4◦ N from near the surface to 500 hPa. Airborne data collected during April 2015 are combined with ground- based observations from the observatory at Alert, Nunavut and simulations from the Goddard Earth Observing Sys- tem (GEOS) model, GEOS-Chem, coupled with the TwO- Moment Aerosol Sectional (TOMAS) model (collectively GEOS-Chem–TOMAS; Kodros et al., 2018) to further our knowledge of the effects of BC on light absorption in the Arctic troposphere. The results are constrained for σsp less than 15 Mm−1, which represent 98 % of the observed σsp, be- cause the single scattering albedo (SSA) has a tendency to be lower at lower σsp, resulting in a larger relative contribution to Arctic warming. At 18.4 m2 g−1, the average BC mass ab- sorption coefficient (MAC) from the combined airborne and Alert observations is substantially higher than the two aver- aged modelled MAC values (13.6 and 9.1 m2 g−1) for two different internal mixing assumptions, the latter of which is based on previous observations. The higher observed MAC value may be explained by an underestimation of BC, the presence of small amounts of dust and/or possible differences in BC microphysics and morphologies between the obser- vations and model. In comparing the observations and simulations, we present σap and SSA, as measured, and σap/2 and the corresponding SSA to encompass the lower modelled MAC that is more consistent with accepted MAC values. Me- dian values of the measured σap, rBC and the organic com- ponent of particles all increase by a factor of 1.8 ± 0.1, going from near-surface to 750 hPa, and values higher than the sur- face persist to 600 hPa. Modelled BC, organics and σap agree with the near-surface measurements but do not reproduce the higher values observed between 900 and 600 hPa. The dif- ferences between modelled and observed optical properties follow the same trend as the differences between the mod- elled and observed concentrations of the carbonaceous com- ponents (black and organic). Model-observation discrepan- cies may be mostly due to the modelled ejection of biomass burning particles only into the boundary layer at the sources. For the assumption of the observed MAC value, the SSA range between 0.88 and 0.94, which is significantly lower than other recent estimates for the Arctic, in part reflecting the constraint of σsp < 15 Mm−1. The large uncertainties in measuring optical properties and BC, and the large differ- ences between measured and modelled values here and in the literature, argue for improved measurements of BC and light absorption by BC and more vertical profiles of aerosol chemistry, microphysics and other optical properties in the Arctic
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