375 research outputs found
A RISK PROGRAMMING APPROACH TO DESIGNING CONTRACTS TO REDUCE NITRATE LEACHING
As contractual agriculture expands, contract design offers a non-regulatory opportunity to reduce non-point source pollution. A risk programming analysis of seed corn contract designs illustrates a tractable empirical principal-agent model, and shows that grower risk preferences affect contract acceptability and efficiency at reducing nitrate leaching.Environmental Economics and Policy, Risk and Uncertainty,
AGRICULTURAL PRODUCTION CONTRACTS TO REDUCE NITRATE LEACHING: A WHOLE-FARM ANALYSIS
Ten alternative seed corn contract specifications are evaluated with respect to nitrate leaching and profitability for the processor firm (principal) and contracted grower (agent). A whole-farm optimization and feasibility analysis suggest that contract terms can be used to reduce non-point source pollution.Crop Production/Industries,
CONTRACT INCENTIVES AND EXCESSIVE NITROGEN USE IN AGRICULTURE
This study examines incentives for input use under tournament contracts. We analyze implications of contract design for nitrate-based environmental externalities generated by agricultural producers. Outcomes are compared from contracts awarded by tournament to those from fixed-payment contracts. Our findings show contract insecurity can distort input use. The model developed in this analysis is applied to a region of the U.S. where tournament-based production is prevalent and groundwater contamination is a problem. We find contract insecurity increases nitrogen use by about 12%, resulting in a 17% increase in nitrate leaching. Implications for contract modification to reduce environmental externalities while maintaining contract incentives are discussed.Crop Production/Industries,
Preventing root caries development under oral biofilm challenge in an artificial mouth
Objectives: To study the preventive effects of chlorhexidine against root caries under oral biofilm in an artificial
mouth.
Study
Design: Sixteen human tooth-root disks
were inoculated
with a salivary sample that
was produced by mixing
the unstimulated saliva of three adults
who had no untreated caries. The disks
were incubated in an artificial
mouth fed
with a 5% sucrose solution three times daily for one
week. Eight disks received a twice daily rinse of
0.12% chlorhexidine (test group). The other eight disks
were rinsed in distilled
water (control). The biofilm
was
then studied
with three techniques: colony forming unit (CFU) counting, scanning electron microscopy (SEM)
and confocal laser scanning microscopy (CLSM). The changes in the chemical structure of the root surface
were
studied using Fourier transform infra-Red spectroscopy. Type-I collagen and proteoglycans on the root surface
were quantified using immunocytochemical staining.
Results: The log CFU for the test and control groups
were 4.21 and 8.27, respectively (p<0.001). The CFU count of
Streptococci and Lactobacilli
were negligible. Both the SEM and the CLSM showed suppressed bacteria growth
in the test group. The log [amide-I: HPO
4 2-] of the test and control groups
were 1.11 and 1.93, respectively (p=0.02).
The mean counts of sound type-I collagen in the test and control groups
were 16.8/µm²
and 13.0/µm², respectively
(p<0.001),
whereas the mean counts of intact proteoglycans
were 5.6/µm²
and 3.5/µm², respectively (P<0.001).
Conclusions: Chlorhexidine suppressed the growth of selected cariogenic bacteria in oral biofilm on the root surface and thus protected tooth-root from cariogenic challenge
Caries arresting effect of silver diamine fluoride on dentine carious lesion with S. mutans and L. acidophilus dual-species cariogenic biofilm
Objectives: This in vitro study investigated the effects of silver diamine fluoride (SDF) on dentine carious lesion
with cariogenic biofilm.
Study Design: Thirty human dentine blocks were inoculated with Streptococcus mutans and Lactobacillus acidophilus
dual-species biofilm to create carious lesion. They were equally divided into test and control group to
receive topical application of SDF and water. After incubation anaerobically using micro-well plate at 37oC for 7
days, the biofilms were evaluated for kinetics, morphology and viability by colony forming units (CFU), scanning
electron microscopy (SEM), and confocal microscopy (CLSM), respectively. The carious lesion underwent crystal
characteristics analysis, evaluation of the changes in chemical structure and density of collagen fibrils using x-ray
diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and immune-labeling.
Results: The log CFU of S. mutans and L. acidophilus in the test group was significantly lower than control group.
SEM and CLSM showed confluent biofilm in control group, but not in test group. XRD showed the loss of crystallinity
of dentine due to the dissolution of hydroxyapatite crystal structure in test group was less than control group.
FTIR showed that log [Amide I: HPO4
2-] for test vs. control group was 0.31±0.10 vs. 0.57±0.13 (p<0.05). The goldlabeling
density in test vs. control group was 8.54±2.44/ìm2 vs. 12.91±4.24/ìm2 (p=0.04).
Conclusions: SDF had antimicrobial activity against the cariogenic biofilms and reduced demineralization of
dentine
Impacts of increasing typhoons on the structure and function of a subtropical forest: reflections of a changing climate
Due to their destructive and sporadic nature, it is often difficult to evaluate and predict the effects of typhoon on forest ecosystem patterns and processes. We used a 21-yr record of litterfall rates to explore the influence of typhoon frequency and intensity, along with other meteorological variables, on ecosystem dynamics in a subtropical rainforest. Over the past half century there has been an increasing frequency of strong typhoons (category 3; >49.6 m s-1; increase of 1.5 typhoons/decade) impacting the Fushan Experimental Forest, Taiwan. At Fushan strong typhoons drive total litterfall mass with an average of 1100 kg ha-1 litterfall typhoon-1. While mean typhoon season litterfall has been observed to vary by an order of magnitude, mean litterfall rates associated with annual leaf senescence vary by <20%. In response to increasing typhoon frequency, total annual litter mass increased gradually over the 21-year record following three major typhoons in 1994. Monthly maximum wind speed was predictive of monthly litterfall, yet the influence of precipitation and temperature was only evident in non-typhoon affected months. The response of this subtropical forest to strong typhoons suggests that increasing typhoon frequency has already shifted ecosystem structure and function (declining carbon sequestration and forest stature)
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Exosomal miRNA 16-5p/29a-3p from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysis.
Over 80% of the patients with pancreatic ductal adenocarcinoma (PDAC) have cachexia/wasting syndrome. Cachexia is associated with reduced survival, decreased quality of life, and higher metastasis rates. Here, we demonstrate that fat loss is the earliest feature of PDAC-exosome-induced cachexia. MicroRNA sequencing of exosomal components from normal and cancer-derived exosomes revealed enrichment of miR-16-5p, miR-21-5p, miR-29a-3p, and miR-125b-5p in serum exosomes of mice harboring PDAC and patients with PDAC. Further, miR-16-5p and miR-29a-3p inhibited adipogenesis through decreasing Erlin2 and Cmpk1 expression which downregulates C/EBPβ and PPARγ. Synergistically, miR-29a-3p promotes lipolysis through increasing ATGL expression by suppressing MCT1 expression. Furthermore, PDAC-exosomes deprived of miR-16-5p and miR-29a-3p fail to induce fat loss. Hence, miR-16-5p and miR-29a-3p exosomal miRs are essential for PDAC-induced fat loss. Thus, we unravel that PDAC induces adipose atrophy via exosomal miRs. This knowledge may provide new diagnostic and therapeutic strategies for PDAC-induced cachexia
The risk of false inclusion of a relative in parentage testing – an in silico population study
Aim To investigate the potential of false inclusion of a
close genetic relative in paternity testing by using computer
generated families.
Methods 10 000 computer-simulated families over three
generations were generated based on genotypes using 15
short tandem repeat loci. These data were used in assessing
the probability of inclusion or exclusion of paternity
when the father is actually a sibling, grandparent, uncle,
half sibling, cousin, or a random male. Further, we considered
a duo case where the mother’s DNA type was not
available and a trio case including the mother’s profile.
Results The data showed that the duo scenario had the
highest and lowest false inclusion rates when considering
a sibling (19.03 ± 0.77%) and a cousin (0.51 ± 0.14%) as
the father, respectively; and the rate when considering a
random male was much lower (0.04 ± 0.04%). The situation
altered slightly with a trio case where the highest rate
(0.56 ± 0.15%) occurred when a paternal uncle was considered
as the father, and the lowest rate (0.03 ± 0.03%) occurred
when a cousin was considered as the father. We also
report on the distribution of the numbers for non-conformity
(non-matching loci) where the father is a close genetic
relative.
Conclusions The results highlight the risk of false inclusion
in parentage testing. These data provide a valuable
reference when incorporating either a mutation in the father’s
DNA type or if a close relative is included as being
the father; particularly when there are varying numbers of
non-matching loci
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