Quantum properties near the instability boundary in optomechanical system

The properties of the system near the instability boundary are very sensitive to external disturbances, which is important for amplifying some physical effects or improving the sensing accuracy. In this paper, the quantum properties near the instability boundary in a simple optomechanical system has been studied by numerical simulations. Calculations show that the transitional region connecting the Gaussian states and the Ring states when crossing the boundary is sometimes different from the region centered on the boundary line, but it is more essential. The change of the mechanical Wigner function in the transitional region directly reflects its bifurcation behavior in classical dynamics. Besides, quantum properties such as mechanical second-order coherence function and optomechanical entanglement, can be used to judge the corresponding bifurcation types and estimate the parameter width and position of the transitional region. The non-Gaussian transitional states exhibit strong entanglement robustness, and the transitional region as a boundary ribbon can be expected to replace the original classical instability boundary line in future applications.

Horizontal Refraction of Acoustic Waves in Shallow-Water Waveguides Due to an Inhomogeneous Bottom Structure

Three-Dimensional (3-D) sound propagation in a shallow-water waveguide with a constant depth and inhomogeneous bottom is studied through numerical simulations. As a model of inhomogeneity, a transitional region between an acoustically soft and hard bottom is considered. Depth-averaged transmission loss simulations using the “horizontal rays and vertical modes” approach and mode parabolic equations demonstrate the horizontal refraction of sound in this region, even if the water column is considered homogeneous. The observed wave effect is prominent at low frequencies, at which the water depth does not exceed a few acoustic wavelengths. The obtained results within the simplified model are verified by the simulations for a real seabed structure in the Kara Sea.

A statistical definition of the Antarctic marginal ice zone

The marginal ice zone (MIZ) is a transitional region between the open ocean and pack ice. This region is circumpolar in the Antarctic, with different sea ice types depending on the season and the sector of the Southern Ocean. The MIZ extent have traditionally been inferred from satellite-derived sea-ice concentration (SIC, one of the essential climate variables), using the 15–80 % range as indicative of sea ice with MIZ characteristics. This proxy has been proven effective in the Arctic, where there is a good correspondence between sea-ice type and sea-ice cover. It is less reliable in the Southern Ocean, where sea-ice type is less linked to the concentration value, since wave penetration and free drift conditions have been reported with 100 % cover. I propose an alternative definition of the MIZ that is based on statistical properties of the SIC and its spatial and temporal variability. The indicator is derived from the standard deviation of daily SIC anomalies, which is often employed in the climate sciences. The use of a monthly climatological mean as the baseline allows to capture changes due to both the seasonal advancement/retreat and the local weather-driven variability typical of less consolidated sea-ice conditions. This method has been tested on the available climate data records to derive maps of the MIZ distribution over the year. It reconciles the discordant seasonal extent estimates using the SIC threshold, which is now independent of the used algorithm. This indicator also allows to derive the climatological probability of exceeding a certain threshold of SIC variability, which can be used for ship navigation, design of observational networks and for testing the skills of sea-ice models in forecasting or climate mode.

Evidence of Deep DOC Enrichment via Particle Export Beneath Subarctic and Northern Subtropical Fronts in the North Pacific

Here we provide compelling evidence that deep particle export enhanced dissolved organic carbon (DOC) concentrations beneath the Pacific’s Subarctic Front (SA, ∼42°N) and Northern Subtropical Front (NST, ∼34°N). We report three main findings: First, deep export of subjectively small particles (128–512 μm) was apparent throughout the frontal zone in which the SA resides. However, export of large particles was specifically associated with the SA, rather than the entire frontal zone, and appeared to exclusively transfer DOC into the bathypelagic water column. Second, a similar DOC enrichment existed beneath the NST, though this signal was curiously not accompanied by observable particles (>128 μm). We conclude that export occurring previously in winter left this DOC behind as a residue, though the associated particles were no longer present by spring. Third, the presence of strong hydrographic fronts was not the only control on export that resulted in these unique DOC distributions. Deep export and DOC enrichment was also controlled by latitude-specific biogeochemical and hydrographic conditions, such as depth of the nutricline and seasonal mixed layer shoaling. Given these observations, the fronts within the transitional region of the North Pacific are clearly special locations for deep carbon sequestration and for providing uncommon DOC enrichment that ultimately supports the deep microbial community.

Determination of The Effect of Different Plant Densities and Nitrogen Doses on Agronomical Traits of Sweet Corn (Zea mays saccharata Sturt.) In Conditions of The Northern-East Transitional Region Conditions of Turkey

This study was carried out to determine the differences in yield and quality characteristics of different plant density and nitrogen doses in sweet corn (Zea mays L. saccharata Sturt) during 2017 and 2018 years. This research was conducted according to a split-plot design with three replications in the Bingol University Faculty of Agriculture Application and Research Farm. Vega sweet corn hybrid was measured with three intra-row spacing (15, 20, 25 cm) and five pure nitrogen doses (0, 80, 160, 240, 320 N kg ha-1) were grown. In the study, the increasing nitrogen dose showed a significant rise in number of ears per plant , number of kernels per ear, relative chlorophyll content, water-soluble solids content, and fresh ear yield . It was determined that plant density positievly effected fresh ear yield; but the number of kernels per ear, the number of ears per plant, relative chlorophyll content were decreased. The highest fresh ear yield was determined D15 (13106 kg ha-1) in terms of plant density and N3 (15905 kg ha-1) in terms of nitrogen dose according to the combined experiment years analysis. Considering the average of years, 240 N kg ha-1 (N3) and approximately 100000 plants per hectare (S15) for optimum the fresh ear yield fertilizer application are recommended.

Soil Mycobiome Is Shaped by Vegetation and Microhabitats: A Regional-Scale Study in Southeastern Brazil

Soil is the principal habitat and reservoir of fungi that act on ecological processes vital for life on Earth. Understanding soil fungal community structures and the patterns of species distribution is crucial, considering climatic change and the increasing anthropic impacts affecting nature. We evaluated the soil fungal diversity in southeastern Brazil, in a transitional region that harbors patches of distinct biomes and ecoregions. The samples originated from eight habitats, namely: semi-deciduous forest, Brazilian savanna, pasture, coffee and sugarcane plantation, abandoned buildings, owls’ and armadillos’ burrows. Forty-four soil samples collected in two periods were evaluated by metagenomic approaches, focusing on the high-throughput DNA sequencing of the ITS2 rDNA region in the Illumina platform. Normalized difference vegetation index (NDVI) was used for vegetation cover analysis. NDVI values showed a linear relationship with both diversity and richness, reinforcing the importance of a healthy vegetation for the establishment of a diverse and complex fungal community. The owls’ burrows presented a peculiar fungal composition, including high rates of Onygenales, commonly associated with keratinous animal wastes, and Trichosporonales, a group of basidiomycetous yeasts. Levels of organic matter and copper influenced all guild communities analyzed, supporting them as important drivers in shaping the fungal communities’ structures.

Identification and characteristics analysis of Meiyu in Anhui Province based on the National Standard of Meiyu monitoring indices

Meiyu is the term used to depict the consecutive rainy weather advancing in the months before the flooding season in East Asia. However, the temporal-spatial climatic characteristics of Meiyu can be differently specified by different evaluation criteria. In this study, we employ both the atmospheric circulation conditions and meteorological factors to identify the spatial characteristics of precipitation of Meiyu in Anhui Province using the collected data of 1957–2020. We further conduct a comparison analysis of the precipitation characteristics in the northern Huaihe River of Aihui province (NHA) with Meiyu rainfall features in two other regions: south of the Yangtze River in Anhui Province (SYA) and the region between the Yangtze River and Huaihe River in Anhui Province (YHA). Finally, the relation between the intensity index between Meiyu and flood or drought is investigated. The results showed that the climatic feature in NHA is a transitional region between Meiyu and non-Meiyu. Also, we proposed a Meiyu intensity index determined by the precipitation amount, intensity, and days of heavy rain. This index performs better than the Meiyu intensity index of National Standard in terms of flood and drought identification.

The Network of Green Infrastructure Based on Ecosystem Services Supply in Central Europe

Green infrastructure is a strategically planned network that broadens traditional biodiversity conservation methods to also encompass the concept of ecosystem services (ES). This study aims to identify the network of green infrastructure in Central Europe. An analysis of ecological connectivity is based on ES supply quantified for CORINE land cover classes. Corridors between core areas, which are represented by Natura 2000 sites, are based on the capacity of ecosystems to supply maintenance and regulating ES. The delineated network of corridors of green infrastructure covers approximately 15% of the landscape of Central Europe that provides high levels of various ES. Ecological corridors create linkages between Natura 2000 sites and support the migration and dispersal of species. Central Europe is an important transitional region where coordinated improvement of ecological connectivity is fundamental. Moreover, promotion of the green infrastructure network and full implementation of the EU Birds and Habitats Directives are targets of two important documents at the European level, the EU Biodiversity Strategy 2030 and the EU Strategy on Green Infrastructure.

Physical Drivers and Dominant Oceanographic Processes on the Uruguayan Margin (Southwestern Atlantic): A Review and a Conceptual Model

The Uruguayan continental margin (UCM), located in the Southwestern Atlantic margin’s subtropical region, is positioned in a critical transitional region regarding the global ocean circulation (Río de la Plata (RdlP) outflow and Brazil-Malvinas Confluence), as also reflected in seafloor features (northernmost distribution of a large depositional contourite system and RdlP paleovalley). This complex oceanographic scenario occurring in a relatively small area highlights the advantage of considering the UCM as a natural laboratory for oceanographic research. The present work provides the first conceptual “control” model of the physical drivers (i.e., climate, geomorphology) and main oceanographic processes (i.e., hydrodynamics, sediment, and carbon dynamics) occurring along the UCM, reviewing and synthesizing available relevant information based on a functional integrated approach. Despite the conspicuous knowledge gaps on critical processes, a general picture of the system’s functioning is emerging for this complex biophysical setting. This includes conceptualizations of the actual controls, main processes, feedbacks, and interactions responsible for system dynamics. The structure adopted for developing our conceptual models allows permanent improvement by empirical testing of the working hypothesis and incorporating new information as scientific knowledge advances. These models can be used as a baseline for developing quantitative models and, as representations of relatively “pristine” conditions, for stressors models by identifying sources of stress and ecological responses of key system attributes under a transboundary approach.