How lateral inhibition and fast retinogeniculo-cortical oscillations create vision: A new hypothesis

The role of the physiological processes involved in human vision escapes clarification in current literature. Many unanswered questions about vision include: 1) whether there is more to lateral inhibition than previously proposed, 2) the role of the discs in rods and cones, 3) how inverted images on the retina are converted to erect images for visual perception, 4) what portion of the image formed on the retina is actually processed in the brain, 5) the reason we have an after-image with antagonistic colors, and 6) how we remember space. This theoretical article attempts to clarify some of the physiological processes involved with human vision. The global integration of visual information is conceptual; therefore, we include illustrations to present our theory. Universally, the eyeball is 2.4 cm and works together with membrane potential, correspondingly representing the retinal layers,photoreceptors, and cortex. Images formed within the photoreceptors must first be converted into chemical signals on the photoreceptors’ individual discs and the signals at each disc are transduced from light photons into electrical signals. We contend that the discs code the electrical signals into accurate distances and are shown in our figures. The pre-existing oscillations among the various cortices including the striate and parietal cortex,and the retina work in unison to create an infrastructure of visual space that functionally ‘‘places” the objects within this ‘‘neural” space. The horizontal layers integrate all discs accurately to create a retina that is pre-coded for distance. Our theory suggests image inversion never takes place on the retina,but rather images fall onto the retina as compressed and coiled, then amplified through lateral inhibition through intensification and amplification on the OFF-center cones. The intensified and amplified images are decompressed and expanded in the brain, which become the images we perceive as external vision

Delayed Southern Hemisphere Climate Change Induced by Stratospheric Ozone Recovery, as Projected by the CMIP5 Models

Stratospheric ozone is expected to recover by the end of this century due to the regulation of ozone depleting substances by the Montreal Protocol. Targeted modeling studies have suggested that the climate response to ozone recovery will greatly oppose the climate response to rising greenhouse-gas (GHG) emissions. However, the extent of this cancellation remains unclear since only a few such studies are available. Here, we analyze a much larger set of simulations performed for the Coupled Model Intercomparison Project, phase 5, all of which include ozone recovery. We show that the closing of the ozone hole will cause a delay in summer-time (DJF) Southern Hemisphere climate change, between now and 2045. Specifically, we find that the position of the jet stream, the width of the subtropical dry-zones, the seasonality of surface temperatures, and sea ice concentrations all exhibit significantly reduced summer-time trends over the first half of the 21st Century as a consequence of ozone recovery. After 2045, forcing from GHG emissions begins to dominate the climate response. Finally, comparing the relative influences of future GHG emissions and historic ozone depletion, we find that the simulated DJF tropospheric circulation changes between 1965-2005 (driven primarily by ozone depletion) are larger than the projected changes in any future scenario over the entire 21st Century

CMIP5 Projections of Arctic Amplification, of the North American/North Atlantic Circulation, and of Their Relationship

Recent studies have hypothesized that Arctic amplification, the enhanced warming of the Arctic region compared to the rest of the globe, will cause changes in midlatitude weather over the twenty-first century. This study exploits the recently completed phase 5 of the Coupled Model Intercomparison Project (CMIP5) and examines 27 state-of-the-art climate models to determine if their projected changes in the midlatitude circulation are consistent with the hypothesized impact of Arctic amplification over North America and the North Atlantic. Under the largest future greenhouse forcing (RCP8.5), it is found that every model, in every season, exhibits Arctic amplification by 2100. At the same time, the projected circulation responses are either opposite in sign to those hypothesized or too widely spread among the models to discern any robust change. However, in a few seasons and for some of the circulation metrics examined, correlations are found between the model spread in Arctic amplification and the model spread in the projected circulation changes. Therefore, while the CMIP5 models offer some evidence that future Arctic warming may be able to modulate some aspects of the midlatitude circulation response in some seasons, the analysis herein leads to the conclusion that the net circulation response in the future is unlikely to be determined solely—or even primarily—by Arctic warming according to the sequence of events recently hypothesized

Response of the Midlatitude Jets, and of Their Variability, to Increased Greenhouse Gases in the CMIP5 Models

This work documents how the midlatitude, eddy-driven jets respond to climate change using model output from phase 5 of the Coupled Model Intercomparison Project (CMIP5). The authors consider separately the North Atlantic, the North Pacific, and the Southern Hemisphere jets. The analysis is not limited to annual-mean changes in the latitude and speed of the jets, but also explores how the variability of each jet changes with increased greenhouse gases. All jets are found to migrate poleward with climate change: the Southern Hemisphere jet shifts poleward by 2° of latitude between the historical period and the end of the twenty-first century in the representative concentration pathway 8.5 (RCP8.5) scenario, whereas both Northern Hemisphere jets shift by only 1°. In addition, the speed of the Southern Hemisphere jet is found to increase markedly (by 1.2 m s−1 between 850 and 700 hPa), while the speed remains nearly constant for both jets in the Northern Hemisphere. More importantly, it is found that the patterns of jet variability are a strong function of the jet position in all three sectors of the globe, and as the jets shift poleward the patterns of variability change. Specifically, for the Southern Hemisphere and the North Atlantic jets, the variability becomes less of a north–south wobbling and more of a pulsing (i.e., variation in jet speed). In contrast, for the North Pacific jet, the variability becomes less of a pulsing and more of a north–south wobbling. These different responses can be understood in terms of Rossby wave breaking, allowing the authors to explain most of the projected jet changes within a single dynamical framework

Robust Wind and Precipitation Responses to the Mount Pinatubo Eruption, as Simulated in the CMIP5 Models

The volcanic eruption of Mount Pinatubo in June 1991 is the largest terrestrial eruption since the beginning of the satellite era. Here, the monthly evolution of atmospheric temperature, zonal winds, and precipitation following the eruption in 14 CMIP5 models is analyzed and strong and robust stratospheric and tropospheric circulation responses are demonstrated in both hemispheres, with tropospheric anomalies maximizing in November 1991. The simulated Southern Hemisphere circulation response projects strongly onto the positive phase of the southern annular mode (SAM), while the Northern Hemisphere exhibits robust North Atlantic and North Pacific responses that differ significantly from that of the typical northern annular mode (NAM) pattern. In contrast, observations show a negative SAM following the eruption, and internal variability must be considered along with forced responses. Indeed, evidence is presented that the observed El Niño climate state during and after this eruption may oppose the eruption-forced positive SAM response, based on the El Niño–Southern Oscillation (ENSO) state and SAM response across the models. The results demonstrate that Pinatubo-like eruptions should be expected to force circulation anomalies across the globe and highlight that great care must be taken in diagnosing the forced response as it may not fall into typical seasonal averages or be guaranteed to project onto typical climate modes.National Science Foundation (U.S.). Climate and Large-Scale Dynamics Program (Grant 1419818)National Science Foundation (U.S.) (Grant 1419667

Achieving cleaner growth in agriculture: establishing feasible mitigation through a bottom-up approach

Achieving climate emissions to meet the 1.5 °C target by 2050 is particularly challenging for the agricultural sector. Cleaner Growth Mitigation Measures (CG-MM) are practices and technologies which balance food production and greenhouse gas abatement and are also identified as being economically acceptable. This paper explores a large number of CG-MMs to assess their feasibility using a novel participatory filtering process. Each measure is explored through a series of mapping exercises with supply chain actors to identify the impact on greenhouse gases and their applicability to different farming systems. These were then refined in a series of farmer workshops to identify which measures were considered feasible to adopt. Results show that acceptance of CG-MMs by the industry and the farmers themselves is limited. A pessimistic estimate of 50 to 60% of potential abatement could be lost due to lack of acceptance of currently available CG-MMs. This impacts expectations on decarbonisation trajectories for the agricultural sector to reach net zero by 2050. This also argues for targeted approaches to agricultural support in order to capture some of the lost abatement

Surface ozone variability and the jet position: Implications for projecting future air quality

Changes in the variability of surface ozone can affect the incidence of ozone pollution events. Analysis of multi-century simulations from a chemistry climate model shows that present-day summertime variability of surface ozone depends strongly on the jet stream position over eastern North America. This relationship holds on decadal time scales under projected climate change scenarios, in which surface ozone variability follows the robust poleward shift of the jet. The correlation between ozone and co-located temperature over eastern North America is also closely tied to the jet position, implying that local ozone-temperature relationships may change as the circulation changes. Jet position can thus serve as a dynamical predictor of future surface ozone variability over eastern North America and may also modulate ozone variability in other northern midlatitude regions

Connections Between the Spring Breakup of the Southern Hemisphere Polar Vortex, Stationary Waves, and Air-sea Roughness

A robust connection between the drag on surface-layer winds and the stratospheric circulation is demonstrated in NASA's Goddard Earth Observing System Chemistry-Climate Model (GEOSCCM). Specifically, an updated parameterization of roughness at the air-sea interface, in which surface roughness is increased for moderate wind speeds (4ms to 20ms), leads to a decrease in model biases in Southern Hemispheric ozone, polar cap temperature, stationary wave heat flux, and springtime vortex breakup. A dynamical mechanism is proposed whereby increased surface roughness leads to improved stationary waves. Increased surface roughness leads to anomalous eddy momentum flux convergence primarily in the Indian Ocean sector (where eddies are strongest climatologically) in September and October. The localization of the eddy momentum flux convergence anomaly in the Indian Ocean sector leads to a zonally asymmetric reduction in zonal wind and, by geostrophy, to a wavenumber-1 stationary wave pattern. This tropospheric stationary wave pattern leads to enhanced upwards wave activity entering the stratosphere. The net effect is an improved Southern Hemisphere vortex: the vortex breaks up earlier in spring (i.e., the spring late-breakup bias is partially ameliorated) yet is no weaker in mid-winter. More than half of the stratospheric biases appear to be related to the surface wind speed biases. As many other chemistry climate models use a similar scheme for their surface layer momentum exchange and have similar biases in the stratosphere, we expect that results from GEOSCCM may be relevant for other climate models

Sustained Benefits of Ranibizumab with or without Laser in Branch Retinal Vein Occlusion: 24-Month Results of the BRIGHTER Study

Purpose To evaluate the long-term (24-month) efficacy and safety of ranibizumab 0.5 mg administered pro re nata (PRN) with or without laser using an individualized visual acuity (VA) stabilization criteria in patients with visual impairment due to macular edema secondary to branch retinal vein occlusion (BRVO). Design Phase IIIb, open-label, randomized, active-controlled, 3-arm, multicenter study. Participants A total of 455 patients. Methods Patients were randomized (2:2:1) to ranibizumab 0.5 mg (n = 183), ranibizumab 0.5 mg with laser (n = 180), or laser (with optional ranibizumab 0.5 mg after month 6; n = 92). After initial 3 monthly injections, patients in the ranibizumab with or without laser arms received VA stabilization criteria-driven PRN treatment. Patients assigned to the laser arm received laser at the investigator's discretion. Main Outcome Measures Mean (and mean average) change in best-corrected visual acuity (BCVA) and central subfield thickness (CSFT) from baseline to month 24, and safety over 24 months. Results A total of 380 patients (83.5%) completed the study. Ranibizumab with or without laser led to superior BCVA outcomes versus laser (monotherapy and combined with ranibizumab from month 6; 17.3/15.5 vs. 11.6 letters; P P P = 0.4259). A greater reduction in CSFT was seen with ranibizumab with or without laser versus laser monotherapy over 24 months from baseline (ranibizumab monotherapy −224.7 μm, ranibizumab with laser −248.9 μm, laser [monotherapy and combined with ranibizumab from month 6] −197.5 μm). Presence of macular ischemia did not affect BCVA outcome or treatment frequency. There were no reports of neovascular glaucoma or iris neovascularization. No new safety signals were identified. Conclusions The BRIGHTER study results confirmed the long-term efficacy and safety profile of PRN dosing driven by individualized VA stabilization criteria using ranibizumab 0.5 mg in patients with BRVO. Addition of laser did not lead to better functional outcomes or lower treatment need. The safety results were consistent with the well-established safety profile of ranibizumab

Individualized Stabilization Criteria-Driven Ranibizumab versus Laser in Branch Retinal Vein Occlusion

Purpose To compare the 6-month efficacy and safety profile of an individualized stabilization criteria-driven pro re nata (PRN) regimen of ranibizumab 0.5 mg with or without laser versus laser alone in patients with visual impairment due to macular edema secondary to branch retinal vein occlusion (BRVO). Design A 24-month, prospective, open-label, randomized, active-controlled, multicenter, phase IIIb study. Participants A total of 455 patients. Methods Eligible patients were randomized 2:2:1 to receive ranibizumab (n = 183), ranibizumab with laser (n = 180), or laser only (n = 92). Patients treated with ranibizumab with or without laser received a minimum of 3 initial monthly ranibizumab injections until visual acuity (VA) stabilization, and VA-based PRN dosing thereafter. In the ranibizumab with laser and laser-only groups, laser was given at the investigator's discretion at a minimum interval of 4 months and if VA was <79 letters. Main Outcome Measures Mean change from baseline at month 6 in best-corrected visual acuity (BCVA) (primary end point) and central subfield thickness, and safety over 6 months. Exploratory objectives were to evaluate the influence of baseline BCVA, disease duration, and ischemia on BCVA outcomes at month 6. Results Baseline mean BCVA was 57.7 letters, and mean BRVO duration was 9.9 months. Ranibizumab with or without laser was superior to laser only in improving mean BCVA from baseline at month 6 (14.8 and 14.8 vs. 6.0 letters; both P < 0.0001; primary end point met). Patients with a shorter BRVO duration at baseline had a higher mean BCVA gain than those with a longer BRVO duration. Patients with a poor baseline VA had a better BCVA gain than those with a higher baseline VA, although final BCVA was lower in those with poor baseline VA. In the ranibizumab with or without laser groups, the presence of some macular ischemia at baseline did not influence mean BCVA gains. There were no new ocular or nonocular safety events. Conclusions Ranibizumab with an individualized VA-based regimen, with or without laser, showed statistically significant superior improvement in BCVA compared with laser alone in patients with BRVO. Overall, there were no new safety events other than those reported in previous studies