How a Brain Sees: Neural Mechanisms

Multiple paradoxical visual percepts are explained using boundary completion and surface filling-in properties, including discounting the illuminant; brightness constancy, contrast, and assimilation; the Craik-O’Brien-Cornsweet Effect; and Glass patterns. Boundaries act as both generators and barriers to filling-in using specific cooperative and competitive interactions. Oriented local contrast detectors, like cortical simple cells, create uncertainties that are resolved using networks of simple, complex, and hypercomplex cells, leading to unexpected insights such as why Roman typeface letter fonts use serifs. Further uncertainties are resolved by interactions with bipole grouping cells. These simple-complex-hypercomplex-bipole networks form a double filter and grouping network that provides unified explanations of texture segregation, hyperacuity, and illusory contour strength. Discounting the illuminant suppresses illumination contaminants so that feature contours can hierarchically induce surface filling-in. These three hierarchical resolutions of uncertainty explain neon color spreading. Why groupings do not penetrate occluding objects is explained, as are percepts of DaVinci stereopsis, the Koffka-Benussi and Kanizsa-Minguzzi rings, and pictures of graffiti artists and Mooney faces. The property of analog coherence is achieved by laminar neocortical circuits. Variations of a shared canonical laminar circuit have explained data about vision, speech, and cognition. The FACADE theory of 3D vision and figure-ground separation explains much more data than a Bayesian model can. The same cortical process that assures consistency of boundary and surface percepts, despite their complementary laws, also explains how figure-ground separation is triggered. It is also explained how cortical areas V2 and V4 regulate seeing and recognition without forcing all occluders to look transparent.

The infancy of core-collapse supernova remnants

ABSTRACT We present 3D hydrodynamic simulations of neutrino-driven supernovae (SNe) with the Prometheus-HotB code, evolving the asymmetrically expanding ejecta from shock breakout until they reach the homologous expansion phase after roughly one year. Our calculations continue the simulations for two red supergiant and two blue supergiant progenitors by Wongwathanarat et al., who investigated the growth of explosion asymmetries produced by hydrodynamic instabilities during the first second of the explosion and their later fragmentation by Rayleigh–Taylor instabilities. We focus on the late time acceleration and inflation of the ejecta caused by the heating due to the radioactive decay of 56Ni to 56Fe and by a new outward-moving shock, which forms when the reverse shock from the He/H-shell interface compresses the central part of the ejecta. The mean velocities of the iron-rich ejecta increase between 100 and 350 km s−1 (∼8–30 per cent), and the fastest 1 per cent of the iron accelerates by up to ∼1000 km s−1 (∼20–25 per cent). This ‘Ni-bubble effect’, known from 1D models, accelerates the bulk of the nickel in our 3D models and causes an inflation of the initially overdense Ni-rich clumps, which leads to underdense, extended fingers, enveloped by overdense skins of compressed surrounding matter. We also provide volume and surface filling factors as well as a spherical harmonics analysis to characterize the spectrum of Ni-clump sizes quantitatively. Three of our four models give volume filling factors larger than 0.3, consistent with what is suggested for SN 1987A by observations.

Energy of adsorption of polar molecules on NaLSX zeolite

The article presents precision data of isotherms and total thermodynamic characteristics, i.e. ΔH, ΔF and ΔS of H2O adsorption on NaLSX zeolite. The stepwise nature of the change in the heat of adsorption on the studied systems with surface filling is revealed, and the molecular mechanism of water adsorption on NaLSX zeolite in the entire filling area is revealed. It was found that the polar water molecule is adsorbed in the NaLSX zeolite in an amount of 31.8 H2O/1/8 e.u., of which 25.3 are in super cavities, and 6.5 are in β-cavities.

To the question of the influence of a silanol cover on the protolytic properties of aminopropyl silica gels

The paper proposes a model that describes the acid-base properties of amino groups grafted onto the surface, taking into account their interaction with silanol groups. For this, aminopropyl silica was chosen as an object with well-studied methods of preparation, structure and properties. The isotherms of sorption of hydrogen ions on aminopropyl silica were obtained by potentiometric method. The experimental points were analyzed numerically, taking into account the presence of an electric double layer, the presence of surface processes competing with the sorption of hydrogen ions, and the peculiarities of the behavior of silanol groups when the degree of surface filling with hydrogen ions changes. The resulting model makes it possible to carry out a preliminary calculation of the sorption of hydrogen ions on the surface of aminopropyl silica.

Large photocurrent density enhancement assisted by non-absorbing spherical dielectric nanoparticles in a GaAs layer

Herein, we report a theoretical investigation of large photocurrent density enhancement in a GaAs absorber layer due to non-absorbing spherical dielectric (SiO2) nanoparticles-based antireflection coating. The nanoparticles are embedded in a dielectric matrix (SiN) which improves the antireflection property of SiN ($$\lambda /4$$ λ / 4 coating) and let to pass more photons into the GaAs layer. The improvement is noticed omnidirectional and the highest is more than 100% at 85° angle of incidence with the nanoparticles’ surface filling density of 70%. Sunrise to sunset calculation of normalized photocurrent density over the course of a year have also shown improvements in the nanoparticles’ case.

The effect of zwitterionic surface content on blood circulation time of nanocapsule

Zwitterionic modification can prolong the blood circulation time of nanocarrier in vivo, but zwitterionic content will affect the functions of nanocarrier such as enzyme-responsive and intracellular or extracellular delivery. Therefore, it is necessary to explore the relationship between the zwitterionic content and circulation time of nanocarrier so as to figure out what content of zwitterion can enable the nanocarrier to obtain both the long blood circulation ability and other functions mentioned above. Herein, using nanocapsule as a research model, we investigated the nanocapsule modified with zwitterion of phosphorylcholine (PC) or carboxybetaine (CB) respectively, and through 1H-NMR quantification we determined the zwitterionic surface content, so as to study the effect of PC or CB surface content on blood circulation performance of nanocapsule. In vivo study showed that the nanocapsule possessed an optimal surface filling ratios range for blood circulation of 43–68% for PC and of 20–68% for CB, with the longest t1/2=37.35 h for PC-nanocapsule and t1/2=45.27 h for CB-nanocapsule. Furthermore, the protein adsorption and macrophage endocytosis experiments indicated that when the surface filling ratio reached 43% for PC-nanocapsule and 20% for CB-nanocapsule, it could effectively reduce the protein adsorption and weaken macrophage endocytosis, thus explaining the phenomenon of long circulation time of nanocapsules from the point of protein adsorption and interaction with immune cells. This study proposes a new direction for designing long-circulating nanocarrier, and provides basis for constructing enzyme-responsive and intracellular or extracellular delivery platform.

Dentition Status and Treatment Needs Among Orphans in Riyadh City, Saudi Arabia: A Cross-sectional Descriptive Study

Background: Oral health affects the general health and quality of life of an individual. It has been well documented that the absence of family support influences the general and oral health of children. Factors that lead to the development of a disease are likely to have their roots in a complex chain of environmental events that may have begun years before the disease occurs. The purpose of this study was to examine the prevalence of dental caries and assess treatment needs of the orphans of Riyadh City, Saudi Arabia Methods: This cross-sectional study included 238 orphaned children aged 6 to 18 years. Clinical examination was conducted by two doctors, and oral findings were recorded according to the World Health Organization (WHO) oral health assessment form (1997). The data collected was analyzed using SPSS 21.0. Results: Results revealed that 37% of the participants reported that they do not brush their teeth, 23%of the participants reported that they do not brush regularly, 17% of the participants reported that they brush one time daily, and 23% of the participants reported that they brush twice daily. The prevalence of dental caries among the participants was 96.6%. When examining treatment needs among study participants, 7.6% might need preventive caries arresting care, 49.6% might need fissure sealant applications, 51.3% might need at least one surface filling, 13.1% might need two or more surface filling, 2.5% might need crown for any reason, 0.4% of participants might need veneer or laminate, 0.2% of participants might need pulp care and restoration, and 8.1% might need extraction. Conclusion: Results of our study indicate that orphan children have low utilization of preventive and therapeutic oral health services. Urgent attention is required to plan a comprehensive dental health-care program to improve their oral health status.

Pulse Electrodeposition of Palladium Nanoparticles onto Silicon in DMSO

The deposition of palladium nanoparticles (PdNPs) on the surface of n-Si (100) substrate by pulsed electrolysis in dimethyl sulfoxide (DMSO) solutions of Pd(NO3)2 was investigated. It has been shown that nonaqueous medium (DMSO) contributes the Pd (II) recovery at high cathode potential values avoiding side processes to occur. In combination with the pulse mode, this allows the deposition of spherical PdNPs with their uniform distribution on the silicon surface. We established that the main factors influencing the geometry of PdNPs are the value of the cathode potential, the concentration of palladium ions in solution, and the number of pulse-pause cycles. It is shown that with increasing Ecathode value there is a tendency to increase the density of silicon surface filling with nanoparticles. As the concentration of Pd(NO3)2 increases from 1 to 6 mM, the density of silicon surface filling with PdNPs and their average size also increase. We found that with increasing the number of pulse-pause cycles, there is a predominant growth of nanoparticles in diameter, which causes 2D filling of the substrate surface.

Research on Reducing Mining-Induced Disasters by Filling in Steeply Inclined Thick Coal Seams

Surface filling during the mining of steeply inclined thick coal seams is an efficient method for restraining disasters caused by the cascading movement of overburden rocks. This study aims to control rock damage during the mining of thick coal seams steeply inclined at typically more than 45° in fully mechanized coal caving work surfaces with high section heights. Based on the green mining concept, we analyzed the movement of roof strata after filling using multiple methods, including field investigation, theoretical analysis, numerical calculation, and field monitoring. Results show that, in dynamic mine disasters caused mainly by complex coal conditions and strong disturbances in fully mechanized coal caving in large sections, the strength of the filling material is dependent on the features of the surrounding rock and burial depth. Also, the mining-induced peak stress shows a linear increase after filling, with the goafs in stress-free conditions, and failure zones occur in the roof and floor strata after mining. The stability of the rock pillars and overburden strata are better, and there are no large-scale tensile fissures in the ground surface. We adopted an intelligent underground radar detection technique that can reflect the rock-failure characteristics through the propagation characteristics of the electromagnetic spectrum. The detection results show that the coal goafs were filled properly as they were matched with the caving roof, which will collapse along with the release of the top coal, with the filling body able to move downward along with the discharge of top coal. The use of surface filling can restrain the dynamic disaster induced by a fully mechanized coal caving surface with a large section when mining steeply inclined thick coal seams, thereby ensuring safety and promoting the use of green mining practices.

On the relationship of oil and gas formation and degassing processes with groundwater decomposition

The article is referred to important consequence of the biosphere oil and gas formation concept, according to which the process of hydrocarbons generation in the subsoil and degassing of the Earth are a single natural phenomenon. The main role in this phenomenon is played by geochemical circulation of carbon and water through the Earth’s surface accompanied by polycondensation synthesis of hydrocarbons by CO2+H2O reaction. This reaction is accompanied by a colossal decomposition of groundwater into hydrogen and oxygen within the sedimentary cover of the earth’s crust. Unreacted CO2, as well as H2 and most of the methane produced during the reaction are degassed into the atmosphere, while resulting C5+ hydrocarbons remain under the surface filling geological traps in the form of oil and gas. The article presents the results of model experiments, which make it possible to estimate the rate of groundwater decomposition and on this basis explain the current rate of Earth’s degassing, as well as the observed CO2, CH4 and H2 ratio in degassing products.