High-density Sections Research Articles

Pruning and Water Saving Management Effects on Mango High-Density and Mature Orchards

Water is getting scarce and irrigation practices should become more efficient. Mango orchards require great quantities of water, and policies in developing countries are substituting surface gravity irrigation by pressurized systems. A commercial orchard having mature 25-year-old trees and a 10-year-old HD high-density section were irrigated with micro sprinklers using 100% ETc (crop evapotranspiration) and reduced deficit irrigation treatments of 75% and 50% ETc. Water soil measurements were made with EC-5 probes at 10 and 35 cm in depth to study the effect of the different irrigation treatments. After the 2020 harvest, mature trees were trimmed without achieving pruning severity greater than 1.3. Canopy volume, mango size, fruit yield and water-use efficiency WUE were analyzed during 2020 and 2021. Sporadic storms produced sprinkler watering problems as weeds proliferated within trees. A controller with a fuzzy algorithm optimized orchard management and saved water in trees without decreasing yield and fruit size. It was found that one year after mature trees were trimmed by taking away the larger internal branch, more light penetrated the canopy, increasing yield by 60%; pruning in HD trees presented a yield increase of 5.37%. WUE (water-use efficiency) also increased with pruning and its value increased to 87.6 when the fuzzy controller and the 50% DI treatments were used in mature trees. This value was 260% greater than the one obtained in pruned trees without the controller. HD trees presented a lower WUE and yield per hectare than mature trees.

A Study on the Design of Coastal Fairway Width Based on a Risk Assessment Model in Korean Waterways

In this study, the appropriate fairway width was designed through the maritime traffic safety evaluation model. By applying the concept of L-converted traffic, it was found that the current maritime traffic volume is 5 to 20 ships per hour in the sea area near Gun-san Port. High-density sections were identified through density analysis based on maritime traffic volume, which ranged from 5 to 10 km, and sections with an area of 10 km or more were also analyzed. Considering the general traffic flow and density, it is necessary to set a route width of 10 km or more in the target sea area, as well as to design a minimum fairway width that ensures safety for all types of ocean use. In this study, four traffic flows were analyzed through machine learning and a comprehensive environmental stress model was created for the traffic flows. The amount of safety change according to the increase in traffic volume was compared and reviewed for a fairway width of 1 km to 10 km, which can be generally formed according to the characteristics of the sea area. In the assessment, we found that when the fairway width was 1–4 km and the L-converted traffic volume was 15 or more, the ES ≥ 750 value exceeded 10% of the total, thus creating a burden on the ship operators. In particular, it was found that the ES ≥ 750 value was 20% at most when the L-converted traffic volume was 20 or more. In a comprehensive analysis, the ES > 750 was found to be less than 10% when the fairway width was 6 km or more in the sea area with one crossing passage at 5 to 20 ships per hour, which was the experimental condition of this study, and the ship operator’s burden was determined to be insignificant. Based on these results, when designing routes between offshore wind farms that will be established in the future, we expect that it will be possible to design the minimum fairway width to ensure safety according to the traffic volume.

Recognition of the atrioventricular node anatomical structure: Connection between the retroaortic node and the compact node.

The complex electrophysiological phenomena related to the atrioventricular node (AVN) are due to its complex anatomical structures. Aside from the inferior nodal extension (INE), other node-like tissues, such as the retroaortic node (RN), have been described less extensively and may also share the mechanism of normal conduction and abnormal conduction in AVN re-entrant tachycardia. High-density sections of the entire AVN were obtained from rats and rabbits. Fibrosis was analyzed by Masson's trichrome staining. Connexin (Cx43, Cx40, and Cx45) and ion channel (Nav 1.5, Cav 3.1, and HCN4) proteins were immunohistochemically labeled for the analysis of tissue features. Three-dimensional (3D) reconstruction of the AV junction was performed to clarify the relationships among different structures. The RN expressed the same connexin isoforms as the compact node (CN) and INE. Nav 1.5 labeling was observed at low levels in the CN, RN, and INE, where Cav 3.1 and HCN4 were expressed. The CN connected with the RN in a narrow strip pattern at the start of the CN. The RN presented as a shuttle shape and was the only tissue directly connected with the atrium in the anterior septum. The RN connects with the AVN anatomically, suggesting that direct electrical conduction occurs between them. The entrance of the atria into the AVN is distal to the RN, which may form the fast AVN pathway.

Impact of Half-Angles on the Transmission of Terahertz Wave in Inhomogeneous Plasma Sheath

Terahertz communication is considered as a potential solution to alleviate the communication blackout. However, it is not clear how the shape parameters of the vehicle affect the propagation of terahertz communications in the plasma sheath. In this article, the influence of half-angle on the plasma flow and terahertz propagation characteristics around blunt cone vehicle was investigated using the numerical hypersonic hydrodynamic model and multilayer transmission model. The maximum electron number density in the plasma sheath near the antenna decreases with the decreasing half-angle. The thickness of the high-density section in the plasma sheath is almost unaffected by the half-angle. As a result, the terahertz wave attenuation decreases with the decreasing half-angle. The half-angle is reduced from 20° to 5°, and the attenuation of electromagnetic waves is reduced by about 25 dB. Therefore, reducing the half-angle of blunt cone vehicle can effectively reduce the attenuation of electromagnetic waves. Finally, the feasibility of lowering the half-angle to solve the blackout problem during the whole reentry process was discussed; the results show the operating frequency of terahertz wave that maintains normal communication when the half-angle is 1° is reduced by 0.1 THz compared with the half-angle of 9°. Based on the study, a new scheme combining the reduction of half-angle of blunt cone vehicle and terahertz communication was proposed in this article to mitigate the RF blackout.

Enhanced reconstruction of structured illumination microscopy on a polarized specimen.

Structured illumination microscopy (SIM) requires polarization control to guarantee the high-contrast illumination pattern. However, this modulated polarization will induce artifacts in SIM when imaging fluorescent dipoles. Here we proposed the polarization weighted recombination of frequency components to reconstruct SIM data with suppressed artifacts and better resolving power. Both the simulation results and experimental data demonstrate that our algorithm can obtain isotropic resolution on dipoles and resolve a clearer structure in high-density sections compared to the conventional algorithm. Our work reinforces the SIM theory and paves the avenue for the application of SIM on a polarized specimen.

Design and operation of a windowless gas target internal to a solenoidal magnet for use with a megawatt electron beam

A windowless hydrogen gas target of nominal thickness $10^{19}$ cm$^{-2}$ is an essential component of the DarkLight experiment, which is designed to utilize the megawatt electron beam at an Energy Recovery Linac (ERL). The design of such a target is challenging because the pressure drops by many orders of magnitude between the central, high-density section of the target and the surrounding beamline, resulting in laminar, transitional, and finally molecular flow regimes. The target system was assembled and operated at Jefferson Lab's Low Energy Recirculator Facility (LERF) in 2016, and subsequently underwent several revisions and calibration tests at MIT Bates in 2017. The system at dynamic equilibrium was simulated in COMSOL to provide a better understanding of its optimal operation at other working points. We have determined that a windowless gas target with sufficiently high density for DarkLight's experimental needs is feasible in an ERL environment.

Mesoscopic Traffic Flow Model Considering Overtaking Requirements

AbstractOvertaking probability formula in the Prigogine—Herman traffic flow mesoscopic model is the function of traffic density, which is a linear function and does not consider overtaking requirements. In this paper, we use desired speed to improve the overtaking probability formula and propose a new overtaking probability formula that is nonlinear and a corresponding traffic flow mesoscopic model. The improved model can simultaneously consider traffic density and overtaking requirements, thus reflecting traffic flow operation realistically. We use the proposed model to simulate the diffusion process of vehicles from a high-density section to a low-density section. The example analyzes the difference between the linear overtaking probability formula and the parabolic Greenshield’s overtaking probability formula. Results show that the linear overtaking probability formula evolves quickly and converges to three speed classes. The parabolic Greenshield’s overtaking probability formula converges to six speed...

A geostatistical approach to spatial density distributions of sika deer (Cervus nippon)

Sika deer (Cervus nippon) cause serious damage to trees in Japanese forests. Browsing, bark stripping, and tree abrasion with antlers account for 50% of total wildlife damage over the past decade. The extent of forest damage depends on deer population density. We determined the spatial distribution of sika deer population density on Mt. Hiko (Fukuoka Prefecture, southwestern Japan). We also investigated changes in population density distribution over time. Determinants of population density were examined, with particular emphasis on the hunting cull. Deer densities in 1999 and 2004 were estimated by fecal pellet counts at 86 sites. We used kriging, a geostatistical technique that is a component of geographic information systems, to interpolate site-specific point data over large areas of landscape. Mapping procedures showed that high-density (≥30.0 deer km−2) and low-density sections of landscape (≤10.0 deer km−2) decreased in areal extent between 1999 and 2004. Contractions of high-density sections were attributable to intensive hunting. In low-density landscape sections, reduced hunting pressure allowed increased persistence of adult animals whose high fecundity led to population growth and higher deer densities. Landscape tracts with medium deer densities (10.0–30.0 deer km−2) expanded, adding further difficulties to the task of wildlife management. Given the scale of the problems caused by deer, it is clear that reliable estimates of population size across space and time are essential components of the wildlife manager's toolbox.

DENSITY REGULATION IN TADPOLES OF RANA TEMPORARIA: A FULL POND FIELD EXPERIMENT

Tadpole density dependence has repeatedly been studied in laboratories and mesocosms, but rarely in natural ponds. The present study manipulated density in three ponds; each pond was divided into one low density section and one high density section. The experiment was run for eight years, switching density treatments within ponds among years. This experimental design cannot definitively separate the experimental density effects from certain lag effects. This problem is discussed. Nonetheless, in all ponds tadpole survival was affected by the density manipulation. The reduced survival of larvae at high density was most pronounced in the pond with the overall highest density. In this pond, the density-dependent mortality almost offset the original, experimental, density difference between sections. Effects on tadpole and metamorph size and development rate were found in those cases in which density-dependent mortality was weak and treatment effects on density persisted to the later stages of tadpole development. However, even if significant, these were generally of small magnitude compared to the variation among ponds and years. I suggest that different modes and degrees of regulation among populations of one species of frog are to be expected, not only due to variation in pond quality but also due to variation in the surrounding terrestrial habitat. This may determine the balance between tadpole and adult population regulation.

Redistribution of juvenile salmonid fishes after localized catastrophic depletion

Juvenile Atlantic salmon and brown trout were depleted at three sites (c. 108–380 m2) of a natural stream during the summer months of 1991 and 1992. Local population changes and movements of fish marked in sections adjacent to each depleted area were monitored thereafter. There was very little movement of marked salmon parr into the central regions of the depleted areas following the immediate post-marking period. Upstream movement by young-of-the-year fish from high density sections in mid-late summer was noted for trout but not salmon. Unmarked 1-year-old salmon parr immigrated into depleted areas in June 1992, and the pattern of recolonization was consistent with migration upstream from the adjoining river. It is concluded that resident salmon were very strongly site-attached and resource tracking was of no functional significance as a compensatory mortality mechanism. The occurrence of a long distance migratory component in the population during early-mid summer indicates that this, rather than local resource tracking, constitutes a potential compensatory mechanism.

Redistribution of juvenile salmonid fishes after localized catastrophic depletion

Juvenile Atlantic salmon and brown trout were depleted at three sites (c. 108–380 m2) of a natural stream during the summer months of 1991 and 1992. Local population changes and movements of fish marked in sections adjacent to each depleted area were monitored thereafter. There was very little movement of marked salmon parr into the central regions of the depleted areas following the immediate post‐marking period. Upstream movement by young‐of‐the‐year fish from high density sections in mid‐late summer was noted for trout but not salmon. Unmarked 1‐year‐old salmon parr immigrated into depleted areas in June 1992, and the pattern of recolonization was consistent with migration upstream from the adjoining river. It is concluded that resident salmon were very strongly site‐attached and resource tracking was of no functional significance as a compensatory mortality mechanism. The occurrence of a long distance migratory component in the population during early‐mid summer indicates that this, rather than local resource tracking, constitutes a potential compensatory mechanism.

Density‐Dependent Effects and the Regulation of Crucian Carp Populations in Single‐Species Ponds

Crucian carp (Carassius carassius) is often the only fish species present in small ponds of northern Europe. Such populations are typically at high densities and consist primarily of small, relatively slender, and short—lived fish; populations in multispecies assemblages in lakes display opposite traits. Field and laboratory experiments have implicated predation as an important mechanism structuring crucian populations in multispecies assemblages. To investigate the role(s) of density dependence in structuring pond populations, we manipulated densities of crucians stocked into four sections of a subdivided natural pond in Finland. Mortality of stocked fish during the 3—mo experiment was low (0—11%) and unrelated to density. Growth rates of crucians were both size and density dependent. Larger fish did not noticeably grow in either high— or low—density sections, but growth of smaller size classes was 22% greater in low—density sections. Lower densities and smaller sizes of zooplankton, especially of inshore cladocerans that are an important food resource for smaller crucians, indicated that resource limitation caused by exploitation competition was an important density—dependent process restricting growth of small fish in high—density sections. Crucians rely on reserves of glycogen, stored in the liver and muscle, to fuel the over winter anerobic metabolism that allows them to maintain populations in ponds where winter hypoxia eliminates other fishes. Liver size was significantly larger and glycogen levels were 82% higher in our low—density pond sections than in high—density sections. At higher, but not lower, densities, relative liver size and glycogen levels decreased with body size; combined with the lack of growth of large fish, this indicates that density—dependent energy limitations contribute to the short life—spans and rarity of large fish that characterize pond populations. An increase in relative body depth can be induced in crucians by the presence of piscivorous fish, reducing vulnerability to predation. It has been proposed that increased body depth incurs a substantial energy cost during swimming and should be restricted to specific size classes in populations sympatric with predators. However, in our experiment, crucians of all sizes became significantly deeper bodied, which contributed to higher condition factors in low—density vs. high—density sections. This morphological change, occurring in the absence of piscivores, suggests that energy benefits (accumulation of overwintering reserves) can override any proposed costs for this sluggish, but metabolically unique, fish. Crucian carp successfully reproduced in all sections during the experiment, but growth and recruitment of 0 + fish (young of year) were strongly and negatively related to the numbers of older fish present. The observed density—dependent recruitment was likely caused by starvation—induced mortality and cannibalism; reduced growth observed in 0 + fish would also be expected to cause higher fist—winter mortality, reducing further recruitment at higher densities. Density dependent has a variety of regulatory effects on pond populations of crucian carp that contribute to their presence and resilence.

Size-dependent Sex Ratios in the Monoecious, Wind-pollinated Annual, Xanthium strumarium

-I examined the numbers and mass of male and female inflorescences produced by the monoecious, wind-pollinated, self-compatible annual, Xanthium strumarium. Sex ratio (number and mass of male flowers number and mass of female flowers) increased with plant size and resource status for greenhouse plants that were experimentally induced to flower, and for naturally occurring plants. Similarly, plants in low-density sections of an experimental garden were larger and had higher sex ratios than those in high-density sections, presumably because of reduced competition. The observed direction of sex change with plant size was unusual, since most species become more female as plant size increases. Sex ratio in this species appeared to be related to branching pattern. Female inflorescences were produced at all nodes, while male inflorescences were absent from about the second to the fourth nodes of main and side shoots. Whole-plant sex ratio may be determined by these location templates for inflorescences, so conditions that alter branching patterns might have important effects on reproductive allocation and reproductive success.

Structure and Annealing Effect of Co-CoO Sputtered Films

Film formed on a slide glass was annealed in a vacuum for five hours to investigate the effects of annealing on magnetic properties and film structure. The density of the Co high-density section near the film surface was found to be almost equal to that of the film fabricated in pure Ar gas, and this seems to be the origin of the observed increase in M s and the decrease in H c (?) and K u . Compared with measurements before annealing, the rising edges found from channel numbers 200 and 320 after annealiing are very steep, showing that separation between the Co and CoO x layers had progressed.