Daylight vision begins when light activates cone photoreceptors in the retina, creating spatial patterns of neural activity. These cone signals are then combined and processed in downstream neural ...circuits, ultimately producing visual perception. Recent technical advances have made it possible to deliver visual stimuli to the retina that probe this processing by the visual system at its elementary resolution of individual cones. Physiological recordings from nonhuman primate retinas reveal the spatial organization of cone signals in retinal ganglion cells, including how signals from cones of different types are combined to support both spatial and color vision. Psychophysical experiments with human subjects characterize the visual sensations evoked by stimulating a single cone, including the perception of color. Future combined physiological and psychophysical experiments focusing on probing the elementary visual inputs are likely to clarify how neural processing generates our perception of the visual world.
Natural enemies and pollinators require nutritional and habitat resources that are often not found in conventional agricultural fields. The addition of flowering plants within agroecosystems may ...provide the resources necessary to support beneficial insects at the local scale. We hypothesized that insect pollinator and natural enemy abundance would increase in cucumber (Cucumis sativus) plots containing flower strips and that the effect would be greatest in the crop rows closest to the flower strips. Three flower treatments were tested: 1) buckwheat (Fagopyrum esculentum), 2) yellow mustard (Brassica hirta), 3) sweet alyssum (Lobularia maritima), and cucumbers as a control. Flowers were planted within a commercial cucumber field in 20-m-long strips in a randomized complete block design with six replications in the 2014 and 2015 growing seasons. Some floral treatments successfully attracted more beneficial insects than others, but the beneficials did not disperse out to the cucumber plants. Cucumber yield was unaffected by flowers with one exception: in 2015, cucumber yield in the sweet alyssum plots were greater than those in plots with no flowers. Our research indicates that adding flowers to cucumber fields to increase services from beneficial insects needs to be further investigated to better understand the effect of factors such as relative flowering strip size.
Summary
Background
Eradication of hepatitis C virus (HCV) infection via interferon‐based treatment lowers hepatocellular carcinoma risk; some research suggests this effect extends to interferon‐free ...treatment.
Aims
The objective of this retrospective cohort study was to examine the association of direct‐acting antiviral (DAA) exposure with risk of incident liver cancer in real‐world data.
Methods
From United States administrative claims data through March 31, 2017, we identified 30 183 adult HCV patients exposed to DAAs. For comparison, we identified contemporary adult HCV patients without evidence of HCV treatment (N = 137 502), and historical HCV patients treated with interferon prior to the introduction of DAAs (N = 12 948). Included patients had at least 12 months of prior enrolment and no evidence of prior liver cancer at baseline. Hazard ratios (HRs) estimating risk of incident liver cancer associated with DAA treatment were calculated using Cox proportional hazards methods.
Results
Relative to untreated HCV patients, DAA‐treated patients were older, more likely to be male, and more likely to have cirrhosis at baseline. After adjustment, DAA treatment was associated with a significantly reduced risk of liver cancer relative to no treatment (adjusted HR = 0.84, 95% CI: 0.73‐0.96), and relative to interferon‐based treatment in the pre‐DAA era (HR = 0.69, 95% CI: 0.59‐0.81).
Conclusions
In this large, population‐based study, DAA‐based treatment was associated with a reduced risk of incident liver cancer relative to both no HCV treatment and to interferon‐based treatment in the pre‐DAA era. As additional follow‐up time of DAA‐treated patients accrues, we anticipate that the long‐term benefits of DAA treatment will become more apparent.
Linked ContentThis article is linked to Hussaini et al, Mahla et al and Singer et al papers. To view these articles visit https://doi.org/10.1111/apt.14634, https://doi.org/10.1111/apt.14795 and https://doi.org/10.1111/apt.14820.
Summary
Portal hypertension is a predictor of liver‐related clinical events and mortality in patients with hepatitis C and cirrhosis. The effect of interferon‐free hepatitis C treatment on portal ...pressure is unknown. Fifty patients with Child‐Pugh‐Turcotte (CPT) A and B cirrhosis and portal hypertension (hepatic venous pressure gradient HVPG >6 mm Hg) were randomized to receive 48 weeks of open‐label sofosbuvir plus ribavirin at Day 1 or after a 24‐week observation period. The primary endpoint was sustained virologic response 12 weeks after therapy (SVR12) in patients who received ≥1 dose of treatment. Secondary endpoints included changes in HVPG, laboratory parameters, and MELD and CPT scores. A subset of patients was followed 48 weeks posttreatment to determine late changes in HVPG. SVR12 occurred in 72% of patients (33/46). In the 37 patients with paired HVPG measurements at baseline and the end of treatment, mean HVPG decreased by ‐1.0 (SD 3.97) mm Hg. Nine patients (24%) had ≥20% decreases in HVPG during treatment. Among 39 patients with pretreatment HVPG ≥12 mm Hg, 27 (69%) achieved SVR12. Four of the 33 (12%) patients with baseline HVPG ≥12 mm Hg had HVPG <12 mm Hg at the end of treatment. Of nine patients with pretreatment HVPG ≥12 mm Hg who achieved SVR12 and completed 48 weeks of follow‐up, eight (89%) had a ≥20% reduction in HVPG, and three reduced their pressure to <12 mm Hg. Patients with chronic HCV and compensated or decompensated cirrhosis who achieve SVR can have clinically meaningful reductions in HVPG at long‐term follow‐up. (EudraCT 2012‐002457‐29).
Optoretinography has enabled noninvasive visualization of physiological changes in cone photoreceptors exposed to light. Understanding the cone optoretinogram in healthy subjects is essential for ...establishing it as a biomarker for cone function in disease. Here, we measure the population cone intensity optoretinogram in healthy adults, for multiple irradiance/duration combinations of visible stimuli with equal energy. We study the within and between session repeatability and reciprocity of the ORG in five healthy subjects. We find the cone optoretinogram exhibits equivalent amplitudes for equal-energy stimuli. We also find good within-subject repeatability, which allows us to show differences across the five subjects.
Conservation tillage combined with cover crops or mulching may enhance natural enemy activity in agroecosystems by reducing soil disturbance and increasing habitat structural complexity. In ...particular, weed seed predation can increase with vegetation cover and reduced tillage, indicating that mulches may improve the quality of the habitat for weed seed foraging. The purpose of this study was to quantify the effects of tillage and mulching for conservation biological control in cucurbit fields. The effects of mulch and reduced tillage on arthropods and rates of weed seed loss from arenas were examined in field trials on sandy soils in 2014 and 2015. Experimental factors included tillage and cover crop, each with two levels: strip-tillage or full-tillage, and cover crop mulch (rye residue) or no cover crop mulch (unmulched). Arthropod abundance on the crop foliage was not affected by tillage or cover crops. Contrary to expectations, epigeal natural enemies of insects and rates of weed seed removal either did not respond to treatments or were greater in full-tilled plots and plots without mulch. Our study demonstrates the potential importance of weed seed predators in reducing weed seedbanks in vegetable agroecosystems, and suggests that early-season tillage may not be detrimental to epigeal predator assemblages.
Impact of conservation agricultural practices on snap bean agroecosystems. Circles denote negative impacts, arrows indicate positive impacts. Solid lines indicate that the effect was measured or ...estimated in this study. Dotted lines indicate hypothesized relationships that were not directly evaluated in this study.
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•We illustrate a cost-avoidance approach to estimate the value of pest-regulating services under CA.•In field experiments in a US bean production system, CA practices resulted in tradeoffs between insect and weed management.•Contrary to expectations, strip tillage (ST) and rye residue retention (R) resulted in net pest-regulating dis-services.•Estimated short-term changes in net returns ranged from losses of $165ha−1 for ST-R to gains of $26ha−1 for ST-NR.•Realization of long-term soil-related benefits of CA may be constrained by short-term increases in pest and input costs.
Although conservation agriculture (CA) practices including strip-tillage (ST) and cover cropping are promoted largely for their potential benefits for soil quality, uncertainty surrounding their short-term effects on pests often constrains adoption. Quantification of ecosystem services or dis-services associated with pests is an important step in identifying research and policy priorities for improving the performance of CA practices. Using insect, weed and yield data from snap beans in a three year vegetable rotation, we estimated the value of pest-regulating services associated with the adoption of CA, and compared it to establishment and management costs associated with implementing CA.
Experimental factors included tillage (full-width tillage FWT or ST), cover crops (winter rye R or none NR) and weed management intensity (low or high). The value of pest-regulating services associated with adoption of CA practices was estimated based on pesticide cost savings associated with reductions in pest densities given action thresholds typical of commercial snap bean production in the North Central United States. CA practices had no detectable impact on snap bean yields relative to FWT-NR, but resulted in significant tradeoffs in weed and insect abundance. For example, in at least one of two years, ST-R had lower densities of potato leafhopper, Powell amaranth and winter annual weeds, but greater densities of tarnished plant bug and large crabgrass compared to FWT-NR. CA practices had variable effects on natural enemies including ladybeetles, spiders and parasitoids, with no consistent impacts relative to FWT-NR. We estimated that CA practices resulted in net pest-regulating dis-services with costs of $33ha−1 for FWT-R, $25ha−1 for ST-NR, and $14ha−1 for ST-R. Under partial adoption of CA (ST-NR), pest-related costs were completely offset by savings in tillage costs, resulting in estimated short-term increases in net returns of $26ha−1. In contrast, complete adoption of CA (ST-R) resulted in greater pest and cover crop management costs that outweighed savings due to reduced tillage, resulting in estimated short-term losses of $165ha−1. In production systems for which effective, low-cost pesticides are unavailable (e.g. low-income countries) or prohibited (e.g. organic systems), the economic impact of pest regulation services is likely to be greater than our estimates suggest. Although CA practices provide several potential long-term ecosystem services at both the farm and landscape level, short-term impacts on pests and yields relative to the costs of implementation are likely to be the major determinant of grower adoption.
Summary
HCV genotype 4 (GT4) has often been overlooked in drug development, even though it infects ~20 million people worldwide. Ledipasvir/sofosbuvir and sofosbuvir/velpatasvir were highly ...efficacious in GT4 HCV‐infected patients from GS‐US‐337‐1119 and GS‐US‐342‐1138. Here, we characterize the resistance profile of ledipasvir (LDV) and velpatasvir (VEL) in patients with GT4 HCV infection. NS5A deep‐sequencing was performed for 454 patients infected with HCV GT4 at baseline, including 44 patients enrolled in GS‐US‐337‐1119 and 116 patients enrolled in GS‐US‐342‐1138, and at relapse for patients with virologic failure. LDV and VEL susceptibilities of 56 patient isolates were determined. In GS‐US‐337‐1119, SVR12 rates were 100% for all subtypes except 4b and 4r. Phenotypic assessment of 56 HCV NS5A patient isolates from various GT4 subtypes indicated that LDV had high potency for the common subtypes 4a/d, and subtypes 4c/f/k/l/m/n/o/p/r/t despite the presence of resistance‐associated substitutions (RASs). For the rare GT4b, LDV median EC50 was higher, but with a broad range of individual values. Importantly, all GT4b isolates tested had 2‐4 NS5A RASs, some including Y93H. Similarly, the 2 GT4r infected patients who had virologic relapse had rare triple RASs. Reversion of these substitutions to the consensus residue significantly increased LDV susceptibility. In GS‐US‐342‐1138, all patients achieved SVR12, regardless of their subtype or presence of RASs. In vitro data confirmed that VEL is potent against all GT4 isolates tested.
LDV and VEL are potent antiviral drugs, estimated to be effective against >95% and >99%, respectively, of GT4 HCV isolates.
Conservation tillage combined with cover crops or mulching may enhance natural enemy activity in agroecosystems by reducing soil disturbance and increasing habitat structural complexity. In ...particular, weed seed predation can increase with vegetation cover and reduced tillage, indicating that mulches may improve the quality of the habitat for weed seed foraging. The purpose of this study was to quantify the effects of tillage and mulching for conservation biological control in cucurbit fields. The effects of mulch and reduced tillage on arthropods and rates of weed seed loss from arenas were examined in field trials on sandy soils in 2014 and 2015. Experimental factors included tillage and cover crop, each with two levels: strip-tillage or full-tillage, and cover crop mulch (rye residue) or no cover crop mulch (unmulched). Arthropod abundance on the crop foliage was not affected by tillage or cover crops. Contrary to expectations, epigeal natural enemies of insects and rates of weed seed removal either did not respond to treatments or were greater in full-tilled plots and plots without mulch. Our study demonstrates the potential importance of weed seed predators in reducing weed seedbanks in vegetable agroecosystems, and suggests that early-season tillage may not be detrimental to epigeal predator assemblages.
Soil nutrient management system characterized by reduced input of inorganic fertilizers integrated with organic amendments is one of the alternatives for reducing deleterious environmental impact of ...synthetic fertilizers, suppressing soil-borne pests and diseases, and improving soil health and crop yield. A hypothesis of the present study was that lower rates of urea mixed with higher rates of plant compost (PC) would improve nematode community structure, soil food web condition, soil biological, and physiochemical properties, and yield and quality of a processing carrot (
) cultivar. Urea and PC were each applied at 135 kg nitrogen (N)/ha alone or at 3:1, 1:1, and 1:3 ratios annually during the 2012 to 2014 growing seasons. A non-amended check served as a control. Nematode community was analyzed from soil samples collected approximately 4-week intervals from planting to 133 days after planting each year. Soil respiration, as a measure of soil biological activity, and soil physiochemical properties were determined from soils collected at planting and at harvest in 2012 and 2013. Results showed that PC alone, and U1:PC1 resulted in soil food web structure significantly above 50 at harvest in 2014. Urea significantly decreased end-of-season soil pH, but increased NO
-N compared with the other treatments. While the herbivore population density was low, abundances of
and
were negatively correlated with carrot fresh weight of marketable carrot. Overall, results suggest that integrating lower rates of urea and higher rates of PC are likely to increase soil biological activity, soil pH, and phosphorus content.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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