Experience-Dependent Development of Feature-Selective Synchronization in the Primary Visual Cortex

Toner charge distributions in corona charged toner layers on a grounded metal plate were investigated. The charge distributions were measured through image analysis of the toner particles displaced onto a filter, depending on their charge to diameter ratio, after being blown off from the toner inlet into an electric field and dispersed. It has been confirmed that the toner charge distributions became broader by corona charging. In order to clarify the cause, dual toner layers have been formed by using different color toners, and the charge distributions at the upper and lower layers have been measured separately. The results show that the lower toner layer has a wider charge distribution than that of the upper layer. This result is attributable to the fact that the lower parts of the toner layer are covered with the upper toner layer and difficult to corona charge. The toner particles in the lower layer located at the opening of the overlapped upper layer tend to be highly corona charged, while the toner particles around the opening in the upper layer receive only a small amount of the corona charge. It has thus been shown that difference in charge distribution between the upper and lower parts of the toner layer is caused by the following mechanisms: 1) The toner particles at the lower part of the layer are shielded from corona charging ions by the upper layer; 2) The toner particles in the lower layer, which are located at the opening of the charged particles in the upper layer, receive more charging ions by concentration of the electric field; 3) The toner particles at the upper layer receive fewer charging ions because of higher electric potential owing to a longer distance from the grounded plate.

On days with clear skies in late August 2002 diurnal changes in the within-branch heterogeneity of photosynthetic photon flux density at the leaf surface (PPFDs) and leaf temperature (T leaf) were measured at natural leaf orientations in the upper and lower layers of a Fagus crenata crown. The PPFDs and T leaf measurements were converted to branch photosynthesis rates (P B; μmol s−1) using a photosynthetic model proposed by Farquhar et al. (Planta 149:78–90, 1980), an empirical stomatal conductance model suggested by Leuning et al. (Plant Cell Environ 18:339–335, 1995), and the total leaf area of the branches. To evaluate the importance of the variation in PPFDs and T leaf on photosynthesis calculations, P B calculated with the observed variation in PPFDs and T leaf was compared with estimates, based on the average (variation-free) values of PPFDs and T leaf, respectively. In both the layers, daily total P B values obtained with T leaf averaging were very close to those obtained with no averaging because of the weak inflection of the net photosynthesis rate (P n) to T leaf curves in the observed T leaf ranges (24.4–36.5 and 21.9–29.1°C in the upper and lower layers, respectively) and relatively small variation in within-branch T leaf at each time of day. This finding applied across potential climate conditions on fine days in August (T leaf range of 19.4–41.5 and 16.9–34.1°C in the upper and lower layers, respectively) and when the spatial scale was increased from branch to leaf layer, which increased the maximum variation in within-branch T leaf from 7.8 to 9.5°C and 4.5 to 5.5°C in the upper and lower layers, respectively. In contrast, averaging PPFDs caused 25–50% and 41–90% overestimation of daily total P B in the upper and lower layers, respectively, due to the sharp curvature in the PPFDs response curve to P n, and relatively large variation in within-branch PPFDs. Further, it led to overestimation of midday depression of P B in the upper layer, possibly because branch structural acclimation to incident light was neglected. Our results indicate that averaged values of T leaf could be used for the estimation of carbon gain at layer scale throughout August, but spatial variations in PPFDs need to be considered in detail for reliable estimates of carbon gain.

Solubility of magnesium hydrogen l-aspartate was examined. This salt is very easily soluble in water but hardly dissolves in organic solvents. In a mixture of water and organic solvents miscible with water, such as methanol, ethanol, propanol, and acetone, the salt distributes between the two layers, forming a dilute solution of the salt in the upper layer and a concentrated solution in the lower layer. The solubility of the slat in the upper layer increases exponentially with the molar fraction of water in the upper layer and the solubility is not affected by temperature. Analysis was carried out on the propanol-water-aspartate system in the upper and lower layers, three-componental phase diagram was prepared, and the Plait point, at which the upper and lower layers agreed, was calculated. It was also found that the exponential function established between the solubility in the upper layer and molar fraction of water thereof is also applicable to the lower layer.

A two‐layer model with a rigid lid and a flat bottom on an f plane is employed to study a flow field driven by a density flux through the sea surface or the coast; for example, freshwater discharged from a river. The negative (positive) density flux into the upper layer is represented by the water beneath (over) the interface changing from the lower (upper) layer to the upper (lower) layer, that is, entrainment of the lower (upper) layer by the upper (lower) layer. The subinertial flow pattern constrained by the coast has two components: one is a baroclinic eddy nearby that matches the entrainment region, and the other is a forced, internal Kelvin wave along the appropriate half of the coast.

The fluid dynamic processes affecting the mechanism and amount of assimilation of the roof of a magma chamber have been studied in a series of analogue laboratory experiments. An aqueous solution of $$Na_{2}CO_{3}$$ was first cooled and crystallized at the top of a laboratory tank to form a solid roof layer of prescribed composition. The tank was then drained and refilled with warmer solution, either $$Na_{2}CO_{3}$$ (of the same or different composition) or, in two experiments, $$KNO_{3}$$. The metal top in all cases was held below the eutectic temperature for the system $$Na_{2}CO_{3}-H_{2}O$$. The experiments were continued until substantial crystallization, and in some cases complete solidification, were achieved. Starting with a dense solid roof layer of $$Na_{2}CO_{3}10H_{2}O$$ and ice on the $$Na_{2}CO_{3}$$ side of the eutectic, and a warmer eutectic $$Na_{2}CO_{3}$$ solution below, there was rapid convective cooling of the liquid layer accompanied by melting of the roof, producing a compositionally dense liquid which convected downwards. When the roof was a solid of eutectic composition and the warm input fluid was much denser, a light stable liquid layer formed. The two liquid layers were separated by a double-diffusive interface through which heat was transported rapidly, but through which there was little mass transfer. As the lower layer cooled and crystallized at the bottom, its $$Na_{2}CO_{3}$$ concentration decreased, and the latent heat released by crystallization was transported upwards through the interface and contributed to the heat required for melting at the roof. In an experiment in which the mean compositions of the roof and the input solution were comparable, melting also led to the development of a stable upper liquid layer, as denser $$Na_{2}CO_{3}10H_{2}O$$ crystals fell off, leaving a lighter melt of eutectic composition behind. With a different denser solute ($$KNO_{3}$$) below, the system at first behaved similarly to the $$Na_{2}CO_{3}$$ experiment and produced a light roof layer, but later the densities of the two liquid layers evolved due to cooling and crystallization until they became equal, resulting in overturning and thorough mixing. The implication for a basaltic magma chamber, in which the magma produced by melting of the roof rocks is lighter than the magma below, is that the melted material will remain at the top of the chamber and be chemically isolated from the basaltic magma at the bottom. The process of AFC (assimilation with fractional crystallization) implies that the heat required for assimilation comes from the latent heat of crystallization, and that these two processes occur simultaneously in a single body of well-mixed magma. The melt released forms a light roof layer which may initially mix with some of the underlying basaltic magma, but then mixes very little. As a consequence, assimilation is separated from the crystallization in space and time. The interface between the upper and lower layers still allows rapid thermal transport vertically, so that crystallization at the floor supplies heat to assimilate the roof, but little roof material is incorporated in the lower layer as it crystallizes. At a later stage the contaminated magma at the roof crystallizes so that fractional crystallization follows assimilation, rather than the two processes occurring simultaneously from the same body of magma. True AFC is confined to the lower basaltic layer but is limited by the amount of material which can be transported across the double-diffusive interface which divides the basaltic layer from the melted roof layer. AFC does become important if large numbers of blocks of the roof fall through the upper layer and melt in the lower layer.

<p>Anisotropy in the Earth’s upper mantle is a signature of past and present deformation. Sri Lanka comprises four main lithological units, viz. the Highland Complex (HC), the Wanni Complex (WC), the Vijayan complex (VC) and the Kadugannawa complex (KC). To calculate the upper mantle anisotropy, we have collected the earthquake data from IRIS (Incorporated Research Institutions for Seismology) network. The upper mantle anisotropy beneath Sri Lanka is measured in the frequency band 0.01–0.15 Hz, with magnitude (Mw) of six or more and within the epicentral distance of 90°-140°. We have analyzed (the fast direction and delay time) shear wave splitting of SKS/SKKS phases at 3 stations, namely, MALK (WC), HALK (HC) and PALK (KC) in Sri Lanka. In this study, shear wave splitting measurements were done using high-quality seismograms (~30) of many earthquakes occurring in the region. We have used rotational correlation (RC) , minimum energy (SC) and eigenvalue techniques. The result of the shear-wave splitting measurement shows the presence of two anisotropic layers in the upper mantle. The upper and lower layer’s fast-polarization direction is found to be NE-SW and NW-SE, has the delay time varies from 0.4-0.5s in the upper layer, and 0.6-0.8s in the lower layer. We found two major fast directions in the upper and lower layers, viz. NE-SW in the upper layer of MALK and PALK and NW-SE for the HALK stations, and NNE-SSW in the lower layer beneath MALK and HALK stations and NW-SE in the PALK station. Overall, Fast direction for Sri Lanka region is found to be NE-SW in the lower layer and NW-SE in the upper layer. Our study suggests that fast axis direction of lower layer with an average delay time of 0.6 s depicts a ~67 km thick anisotropic layer with 4% anisotropy (from previous studies) beneath Sri Lanka region. However, if we assume an anisotropy range of 3–5%, then the calculated delay time of 0.6 s would correspond to thickness variation of 89.3 to 53.59 km, respectively, for the inferred anisotropic layer. Comparing from APM (Absolute Plate Motion) direction with our fast directions, we infer that the SAF(Simple Asthenospheric Flow) model prevails in this region and secondly, when S<sub>hmax </sub>(Maximum Horizontal stress) and the GPS (Global Positioning System) data compared with the fast direction we infer that there is partial contribution from lithospheric mantle. So, we confirmed that anisotropy in the region is mainly governed by asthenospheric flow and partially due to lithospheric mantle.</p>

Priming effect is one of the important mechanisms regulating soil organic matter decomposition. However, the variation of priming effects in different soil layers remains unclear. In this study, we conducted a 30-day incubation experiment using no-tillage black soil from northeastern China. 13C-glucose and dynamic CO2 trapping methods were employed to investigate soil organic carbon (SOC) mineralization rates and the priming effect of the added 13C-glucose in the upper soil layer (0-10 cm) and the lower soil layer (30-40 cm). Our results showed that the cumulative SOC-specific mineralization rate in the upper layer was similar to that in the lower layer soil without glucose addition. Glucose addition significantly altered the mineralization rates in both layers, resulting in a positive priming effect (36.7%) in the upper layer but a negative priming effect (-12.4%) in the lower layer. The cumulative priming effect during the 30-day incubation was 3.24 mg C·g-1 SOC for the upper layer soil and -1.24 mg C·g-1 SOC for the lower layer soil. There was still a net SOC increase, even with positive priming effects in the upper layer soil. This was due to considerable amount of added glucose-C remained un-mineralized in the soil which would compensate the carbon loss from priming effects. Overall, our results demonstrated that the magnitude and direction of priming effects might differ between soil layers. Our findings contribute to a better understanding of the effects of conservation tillage practices (no-tillage and straw incorporation) on soil organic matter dynamics in agroecosystems.

We have succeeded in generating B cell colonies from freshly separated human peripheral blood by the double agar layer technique and expanding them in liquid culture for several weeks. Populations of cells enriched in B cells were placed into the upper layer with or without bacterial LPS. Although B cell colonies were observed without LPS, the addition of LPS to the cells in the upper agar layer increased the number of colonies. Also necessary for optimal B cell colony formation was the presence in the lower agar layer of either culture supernatant of PHA-stimulated mononuclear cells or purified T cells and PHA. Without such helper factors in the lower layer, only a few B cell colonies were observed in the upper layer. By using these techniques, peripheral blood lymphocytes from normal individuals and patients with active systemic lupus erythematosus (SLE) were studied for the generation of B cell colonies. Significantly more B cell colonies were observed in patients with SLE, using either kind of "helper" factor. In addition, T cells from normal individuals and patients were tested for their ability to help B cell colony formation. The SLE T cells were found to be defective in this function relative to normal T cells. Thus, although patients with SLE were hyperactive in forming B cell colonies, thier T cells were defective in supporting the formation of B cell colonies from normal individuals.

The air pressures in coastal unsaturated zones fluctuate in response to tidal fluctuations. Two‐phase air‐water flow induced by sea tides in a coastal two‐layered subsurface system is investigated through numerical simulations. The system consists of upper and lower layers with permeabilities of kU and kL, respectively. A water table exists in the lower layer. The study demonstrates that airflow in the unsaturated zone is controlled by permeabilities of both layers and the fluctuation of water level. The tide‐induced water level fluctuation may result in significant air pressure fluctuation in the unsaturated zone in an air‐confined system; that is, the permeability of the upper layer is about 2 orders of magnitude lower than that of the lower layer. In such an air‐confined system, horizontal airflow is dominant in the lower layer and vertical airflow is dominant in the upper layer. The simulation results show that the hydraulic head, rather than the sea tide, is the direct driving force of the air pressure fluctuation above the water table. The study on the relation between the air pressure amplitude and the landward distance demonstrates that the air pressure amplitudes increase to a maximum and then decrease with distance. The amplitude of air pressure fluctuation decreases progressively with kU in the lower layer. In the upper layer, however, the amplitude tends to increase with kU when kU is very low and decrease with kU when kU is relatively high. Overall, the air flux fluctuations across the atmosphere‐soil interface attenuate landward gradually, and this attenuation becomes faster as the permeability of the upper layer increases.

Expressions for the drain flow, the surface inflow distribution , and flow nets are derived for surface water seeping into drain tubes embedded in water‐saturated soil consisting of two horizontal strata of different permeabilities. In Part I, the drain tubes are located in the upper layer. Numerical results are presented. It is shown in the case of the flow nets how Kennelly's tables of the complex hyperbolic sine may be used to obtain numerical values for equipotentials and stream lines simultaneously. The flow nets, as well as other results, show that unless the lower layer is of high permeability compared to the upper layer, the lower layer has little effect on the flow.In Part II, the drain tubes are located in the lower layer which extends to great depth. It is shown that, unless the drain tubes are very near the upper layer, or unless the upper and lower layers are of approximately the same permeability, fee lower layer governs the flow. Quantitative results are worked out for several cases, including a flow net. The mathematical analysis in both cases is presented in some detail. This is done so that the reader will be able to work out certain details readily for himself. But the material is presented in such a way that readers not desiring to follow mathematical details may, without loss of continuity, skip all but the first few paragraphs of the Analysis and proceed to Results and Discussion.

1. We recorded local field potentials in the parafoveal representation in the primary visual cortex of anesthetized and paralyzed macaque monkeys with a multicontact electrode that provided for sampling of neural activity at 16 sites along a vertical penetration. Differential recordings at adjacent contacts were transformed into an estimate of current source density (CSD), to provide a measure of local neural activity. 2. We used m-sequence stimuli to map the region of visual space that provided input to the recording site. The local field potential recorded in macaque V1 has a population receptive field (PRF) size of approximately 2 deg2. 3. We assessed spatial tuning by the responses to two-dimensional Gaussian noise, spatially filtered to retain power only within one octave. Responses to achromatic band-limited noise stimuli revealed a prominent band-pass spatial tuning in the upper layers, but a more low-pass spatial tuning in lower layers. 4. We assessed orientation tuning by the responses to band-limited noise whose spectrum was further restricted to lie within 45 degrees wedges. The local field potential showed evidence of orientation tuning at most sites. Orientation tuning in upper and lower layers was manifest by systematic variations not only in response size but also in response dynamics. 5. We assessed chromatic tuning by the responses to isotropic band-limited noise modulated in a variety of directions in tristimulus space. Some lower-layer locations showed a nulling of response under near-isoluminant conditions. However, response dynamics in upper and lower layers depended not only on luminance contrast, but also on chromatic inputs. 6. Responses to near-isoluminant stimuli and to low-contrast luminance modulation were shifted to lower spatial frequencies. 7. We determined the extent to which various temporal frequencies in the response conveyed information concerning spatial frequency, orientation, and color under the steady-state conditions used in these studies. In each case, information is distributed in the response dynamics across a broad temporal frequency range, beginning at 4 Hz (the lowest frequency used). For spatial frequency the information rate remains significant up to at least 25 Hz. For orientation tuning and chromatic tuning, the information rate is lower overall and remains significant up to 13 Hz. In contrast, for texture discrimination, information is shifted to lower temporal frequencies.

Hexachlorobenzene dechlorination in constructed wetland mesocosms

Leakage current mechanism and effect of Y2O3 doped with Zr high-K gate dielectrics

Levels of type VI collagen mRNAs were determined in cultured skin fibroblasts derived from the upper, middle, and lower layers. The level of alpha 1 (VI) collagen mRNA was the highest in the fibroblasts from the upper layer. In contrast, alpha 2 (VI) collagen mRNA level in the fibroblasts from the lower layer predominated over those in the upper and middle layers. The level of alpha 3 (VI) collagen mRNA was the same in the three dermal layers. When the fibroblasts from the upper layer were passaged successively, the alpha 1 (VI) collagen mRNA level declined and alpha 2 (VI) collagen mRNA level increased to those of the lower dermal fibroblasts. These results indicate that alpha 1 (VI) and alpha 2 (VI) collagen expressions in skin fibroblast cultures are heterogeneous and that successive passages of the upper dermal fibroblasts may result in transition of the phenotype of alpha 1 (VI) and alpha 2 (VI) expression to that of lower dermal fibroblasts. The modulation of the expression of alpha 1 (VI) and alpha 2 (VI) chains presumably reflects the process of cellular aging in vitro and should be a useful biochemical marker in studies of cell aging.

Estimation of impact sound reduction by wood flooring installation in a wooden building in Korea