Search

Argues in favor of a Chippewa right to harvest maple sap from trees on federal land. Discusses the history of Indian production of and trade in maple sugar, examines relevant treaties, and draws parallels with tribal rights to fish and harvest wild rice. Contains 91 references. (SV)

Provides instructional strategies for using fall fruits/vegetables in science lessons, including activities related to melons, pumpkins, grapes, pears, squash, and yams. Suggests extending the activities over a month or more to allow children time to explore and investigate. (JN)

There is a large biomass potential in harvesting brushwood and young trees on roadsides in Sweden (about 3 PJ yr−1). In this study, a simulation model for analyzing time consumption and profitability of strip-harvesting brushwood and young trees under different conditions was developed and validated. A simple stand generator was used to generate twenty-nine stand types with an average diameter at breast height (DBH) ranging from 4–10 cm and stand density from 2,500 to 20,000 stems ha−1. Thereafter, harvest of these stands was simulated and analyzed. The results showed a positive correlation between harvester performance, DBH, and stand density. At approx. 10,000 stems ha−1, however, the performance flattened out. There was a clear relationship between costs and the number of stems felled. In contrast, the cost per tonne of dry matter was governed by a combination of tree size and number of trees felled (lowest cost when felling many thicker stems and vice versa). It was concluded that this simulation model, using data that was quite easy to obtain, can address one of the main challenges for brushwood harvesting, i.e. identifying areas where operations will be profitable. [ABSTRACT FROM AUTHOR]

This paper deals with a class of parabolic reaction-diffusion equations driven by the fractional Laplacian as the diffusion operator over a bounded domain with zero Dirichlet external condition. Using a comparison principle and monotone iteration method, we establish existence and uniqueness results. We apply the existence result to the logistic growth problems with constant yield harvesting by constructing an ordered pair of positive sub- and supersolution of the corresponding elliptic problem. [ABSTRACT FROM AUTHOR]

In an ecosystem, harvesting infected prey can assist in managing and containing the spread of the illness within the prey species. On the other hand, the harvesting of predators can be beneficial as it regulates their numbers, preventing them from over-consuming prey and subsequently preserving existence of the prey population. This study introduces a predator–prey model that encompasses prey infection, predator–prey interactions influenced by fear, switching and harvesting. We derive an analytic expression for the basic reproduction number, a critical determinant of disease spread. We investigate the global stability of disease-free and endemic equilibria contingent on the basic reproduction number’s value, highlighting the potential for disease eradication by maintaining it below unity. In-depth analysis of the deterministic model is undertaken, with a focus on Hopf bifurcations that delineate thresholds for disease-free and endemic states. Furthermore, the deterministic model is extended to incorporate environmental stochasticity. We obtain the conditions under which population extinction occurs. Our findings elucidate how the intensity of environmental noise influences population dynamics, providing valuable insights into extinction risks under varying noise levels. [ABSTRACT FROM AUTHOR]

This study investigates the global well-posedness of a coupled Navier–Stokes–Darcy model incorporating the Beavers–Joseph–Saffman–Jones interface boundary condition in two-dimensional Euclidean space. We establish the existence of global strong solutions for the system in both linear and nonlinear cases where porosity depends on pressure. When dealing with the time-dependent porous media, the primary challenge in obtaining closed prior estimates arises from the presence of complex, sharp interfaces. To address this issue, we employ the classical Trace Theorem. Such space-time variable coupled systems are crucial for understanding underground fluid flow. [ABSTRACT FROM AUTHOR]

The analysis of algebraic invariants of algebras induced by appropriated multiset systems called Brauer configurations is a Brauer analysis of the data defining the multisets. Giving a complete description of such algebraic invariants (e.g., giving a closed formula for the dimensions of algebras induced by significant classes of Brauer configurations) is generally a tricky problem. Ringel previously proposed an analysis of this type in the case of Dynkin algebras, for which so-called Dynkin functions were used to study the numerical behavior of invariants associated with such algebras. This paper introduces two additional tools (the entropy and the covering graph of a Brauer configuration) for Brauer analysis, which is applied to Dynkin and Euclidean diagrams to define Dynkin functions associated with Brauer configuration algebras. Properties of graph entropies defined by the corresponding covering graphs are given to establish relationships between the theory of Dynkin functions, the Brauer configuration algebras theory, and the topological content information theory. [ABSTRACT FROM AUTHOR]

In the paper, a predator-prey model with the Allee effect and harvesting effort was proposed to explore the interaction mechanism between prey and predator. Under the framework of mathematical theory deduction, some conditions for the occurrence of transcritical, saddle-node, Hopf, and Bogdanov-Takens bifurcations were derived with harvesting effort and the Allee effect as key parameters. Under the framework of bifurcation dynamics numerical simulation, the evolution process of specific bifurcation dynamics behavior was gradually visualized to reveal the influence mechanism of the Allee effect and harvesting effort. The research results indicated that the Allee effect and harvesting effort not only seriously affected the bifurcation dynamics essential characteristics of the model (1.3), but also could promote the formation of constant steady state and periodic oscillation persistent survival mode of prey and predator. Furthermore, it is worth noting that appropriate harvesting effort was beneficial for the formation of a sustainable survival cycle between prey and predator. In summary, we hoped that the research findings could contribute to the comprehensive promotion of bifurcation dynamics studies in the predator-prey model. [ABSTRACT FROM AUTHOR]

A Leslie–Gower predator–prey model with nonlinear harvesting and a generalist predator is considered in this paper. It is shown that the degenerate positive equilibrium of the system is a cusp of codimension up to 4, and the system admits the cusp-type degenerate Bogdanov–Takens bifurcation of codimension 4. Moreover, the system has a weak focus of at least order 3 and can undergo degenerate Hopf bifurcation of codimension 3. We verify, through numerical simulations, that the system admits three different stable states, such as a stable fixed point and three limit cycles (the middle one is unstable), or two stable fixed points and two limit cycles. Our results reveal that nonlinear harvesting and a generalist predator can lead to richer dynamics and bifurcations (such as three limit cycles or tristability); specifically, harvesting can cause the extinction of prey, but a generalist predator provides some protection for the predator in the absence of prey. [ABSTRACT FROM AUTHOR]

Downstream costs represent one of the main obstacles to enabling microalgae to become widespread. The development of an economical, easily scaled-up strategy could reduce the overall process costs. Here, different flocculants were tested on different microalgae strains and a cyanobacterium. The results indicate that flocculation could be an alternative to centrifugation, as CaCl2 induced a complete flocculation of green and red marine strains (96 ± 4% and 87.0 ± 0.5%, respectively), whereas Chitosan was the only agent able to induce flocculation on the cyanobacterium (46 ± 1%). As for the thermoacidophilic red microalga, 100% flocculation was achieved only by increasing the pH. Carotenoids were extracted from the flocculated biomass, and the strategy improved with the use of the wet biomass. The results indicate that flocculation does not affect carotenoid yield, which is at least the same than that obtained upon centrifugation and extraction from the wet biomass. Then, for the first time, the biological activity of the extracts obtained from the flocculated biomasses was evaluated. The results indicate that only the green microalga extract shows increased antioxidant activity. In conclusion, this work highlights that a general downstream procedure cannot be developed for microalgae strains but should be rationally tailored. [ABSTRACT FROM AUTHOR]

Extensive farmland in Europe hosts high biodiversity levels but is threatened by land use changes associated with market and agricultural policy drivers. We show that a nationwide replacement of rainfed cereals in favor of beef production in Portugal has coincided with a nearly 80% decline in the population of a ground‐nesting raptor, the Montagu's harrier Circus pygargus, since 2002. Reduced cereal crop cover led to nesting attempts occurring mostly in fodder crops, the predominant habitat with suitable sward structure at the onset of breeding. This results in a twofold ecological trap: early hay harvesting destroys first nesting attempts, whereas late cereal harvesting destroys replacement clutches. This double phenological mismatch prevents any breeding success and likely explains the country's observed population decline of Montagu's harriers and other key farmland birds. Reforming current agroenvironmental schemes to promote practices compatible with wild population phenology is paramount to revert these changes. [ABSTRACT FROM AUTHOR]

The interconnectedness of adjacent freshwater and terrestrial ecosystems results in ‘tangled‐webs’, where the cross‐boundary exchange of materials results in energy flows that provide critical resources for ecosystem productivity. However, these energy flows can be disrupted by anthropogenic activities, resulting in modified ecosystem functioning. A ubiquitous anthropogenic activity in fresh waters is recreational angling. Five major angling activities can disrupt the structure of the ‘tangled‐web’ to produce an ‘angled‐web’ (a tangled food web that is modified by angling activities). (1) Fish stocking increases the number and species available to exploit, but the increased fish abundances can have strong top‐down effects and disrupt reciprocal prey subsidies. Following capture, fish are either (2) harvested or (3) released alive (‘catch‐and‐release0’); both can both drive eco‐evolutionary changes that can modify food‐web structure. Where fish are exploited using baited hooks, (4) the release of ‘ground‐bait’ is used as a fish attractant; its composition of novel protein and carbohydrate sources form novel trophic links in the food web and can accelerate eutrophication. Some angling styles also require (5) riparian and in‐stream vegetation to be cleared to minimise gear fouling, potentially modifying fish spawning and nursery areas. We suggest that each of these angling impacts (and their interactions) can contribute to transforming the ‘tangled web’ into an ‘angled‐web’, with the strength and direction of the transformation dependent on angling pressure, prevailing fishery practices, regulations and management, and the extent of the interaction effects of the activities. These interactions and their impacts will vary globally given angling methods, practices and regulations differ across the world. We argue that, in this era of substantial environmental change driven by climate change, habitat loss and nutrient enrichment of fresh waters, the extent to which angling impacts food webs should not be overlooked and underappreciated. We emphasise that when freshwater angling activities are poorly managed and/or unregulated, they can strongly modify the interconnectedness between terrestrial and freshwater food webs. [ABSTRACT FROM AUTHOR]

Decreased availability and rising cost in labor poses a serious threat to the long‐term profitability and sustainability of the apple industry in the United States and many other countries. Harvest automation is thus urgently needed. In this paper, we present the unified system design and field evaluation of a new apple harvesting robot. The robot is mainly composed of a specially designed perception component, a four‐degree‐of‐freedom manipulator, an improved vacuum‐based soft end‐effector, and a dropping/catching component to receive and transport picked fruits. Software algorithms are developed to enable synergistic coordination of the hardware components for efficient, automated harvesting of apples in challenging orchard environments. Specifically, by integrating modified triangulation and image processing and analysis algorithms, a novel perception strategy is developed to achieve robust apple detection and precise localization. Improved planning and control algorithms are developed to guide the robot to the target positions. The performance of the robotic system was evaluated through field tests in two apple orchards with different tree architectures and foliage conditions. In the orchard where trees were young and well‐pruned, the robot achieved 82.4% successful harvesting rate. In a second, older orchard with dense, clustered branches and foliage, the robot had 65.2% successful rate. The average cycle time to harvest a fruit was approximately 6 s, which included software algorithm processing and hardware execution. Moreover, through an in‐depth analysis of the obtained results, limitations and planned future works are discussed. [ABSTRACT FROM AUTHOR]

Dredge is the dominant shellfish fishing gear in Sedati District, this tool has good productivity in the shellfish fishing business. The productivity of fishing gear is related to the ability of fishing gear to provide better catches and the profits obtained by fishermen. This research aims to analyze business finances and the feasibility of shellfish fishing using fishing gear in Sedati Waters, Sidoarjo, East Java, Indonesia. This research used a survey research method with Primary and Secondary data. The samples collected from this study were spread across 224 respondents. The hauling process is carried out while catching shellfish 100-150 times. Shellfish fishing activities are carried out 20-26 days a month. The research results show that the average investment cost for a shellfish fishing business is IDR 31,340,000, fixed costs are IDR 6,988,973 and variable costs are IDR 26,600,000. The shellfish catch obtained by fishermen in one year is around 158 kg - 302 kg, with an average per fisherman of 226 kg consisting of Anadara antiquata, Anadara granosa, and Paratape undulatus batik with a total of IDR 68,380,000. The Net Present Value (NPV) value for the clam fishing business was IDR 75,607,420.00, IRR 72.66%, B/C Ratio 1.39, and the Payback Period was 1.64. By addressing these financial factors, a clam harvesting operation with dredging equipment can be efficiently planned and conducted, ensuring both economic feasibility and operational success. [ABSTRACT FROM AUTHOR]

The world's forests are being increasingly disturbed from exposure to the compounding impacts of land use and climate change, in addition to natural disturbance regimes. Boreal forests have a lower level of deforestation compared to tropical forests, and while they have higher levels of natural disturbances, the accumulated impact of forest management for commodity production coupled with worsening fire weather conditions and other climate-related stressors is resulting in ecosystem degradation and loss of biodiversity. We used satellite-based time-series analysis of two canopy indices—canopy photosynthesis and canopy water stress—to calculate an index that maps the relative stability of forest canopies in the Canadian provinces of Ontario and Quebec. By drawing upon available spatial time-series data on logging, wildfire, and insect infestation impacts, we were able to attribute the causal determinants of areas identified as having unstable forest canopy. The slope of the two indices that comprise the stability index also provided information as to where the forest is recovering from prior disturbances. The stability analyses and associated spatial datasets are available in an interactive web-based mapping app. that can be used to map disturbed forest canopies and the attribution of disturbances to human or natural causes. This information can assist decision-makers in identifying areas that are potentially ecologically degraded and in need of restoration and those stable areas that are a priority for protection. [ABSTRACT FROM AUTHOR]

The over‐exploitation of wild birds and the products derived from them can be a key threat driving changes in bird species richness and abundance. However, inadequate information on harvest levels combined with irregular population monitoring often means that the role of harvesting in population decline is difficult to quantify. Historically, the pan‐tropical Sooty Tern Onychoprion fuscatus has been subjected to extensive egg harvesting, yet the role of sustained harvesting in population change and future population viability remains unclear. In this study, we used published and new estimates of key demographic rates for a large, harvested Sooty Tern population in Seychelles, western Indian Ocean, to run a series of population viability analyses. We retrospectively assess the impact of historical levels of egg harvesting, and also predict how this population may respond under different future harvesting regimes, assuming no additional environmental change. We provide evidence that egg harvesting has played a substantial role in driving the population decline of Sooty Terns to date and demonstrate that continued harvesting will probably lead to further, possibly dramatic, declines in population size. These results indicate that recent levels of egg harvesting in Seychelles are not sustainable. We also show that the life‐history strategy of Sooty Terns, including a delayed age of first breeding, means the current 2‐year local moratorium on egg harvesting is unlikely to generate an observable population‐level response in Seychelles. Instead, we recommend that the current moratorium is extended at least beyond the age of first breeding (i.e. 5 years) to support appropriate evaluation. We additionally show that harvesting Sooty Tern eggs at much lower levels, i.e. 10% of the population size, is unlikely to reverse population decline. Therefore, long‐term egg harvesting strategies require careful evaluation to maintain a balance between the social, commercial, cultural and biodiversity significance of Sooty Terns in Seychelles. [ABSTRACT FROM AUTHOR]

The paper examines the fish population dynamics of a delay logistic model with restrictions on harvesting in a deterministic environment. This is the first time an autonomous model with a harvesting function has been created to regulate the harvesting of fish. The goal of the study is to help external regulatory bodies manage fishing harvests and replenish fish stocks. The dynamics scenario mirrors the facts of fishing systems and enhances the research that has already been done. Two restriction conditions are employed. In the event that the agency detects overfishing, all fish harvesting is prohibited, with the fishing control parameter raised in order to bring the fish back to full stock, while the catchability coefficient is set to zero. However, if the system is designed so that harvesting is carried out in accordance with the fish's sustainable growth level, then we have the partial restriction condition where no ban is imposed on fishing. This model's practical benefit is its adaptability; it may be redesigned to suit any physical system whose functioning is comparable to this phenomenon. As a result, it is advised that the regulatory bodies use the model to manage the fish stock. [ABSTRACT FROM AUTHOR]

This paper establishes a prey–predator model with a Holling type IV functional response and proportional harvesting in prey species and nonlinear harvesting in predator species. We provide a completely local and global bifurcation analysis of the model to characterize some meaningful results that may emerge from the interaction of biological resources. The proposed model exhibits various complex behaviors involving heteroclinic and homoclinic orbits, and we prove analytically that it also undergoes transcritical, Hopf, and Bogdanov–Takens bifurcations in the prey–predator plane. Moreover, the system is unfolded to compute the bifurcation curves, highlighting the critical dynamics by perturbing two bifurcation parameters near the cusp. Furthermore, from the economic point of view, the bionomic equilibrium of the system is studied, and optimal harvesting policy is derived using the Pontryagin’s maximum principle. Numerical simulations are presented to verify our analytical results. [ABSTRACT FROM AUTHOR]

This article aimed to enhance the management of the fish supply chain as a perishable commodity and to increase consumer trust. The fish supply chain begins with harvesting, whether from natural fisheries or the aquaculture sector, and extends through to marketing. It encompasses the hygienic practices of all involved parties, including suppliers, fishermen, retailers, storage facilities, distributors, transporters, and marketers. Proper hygienic handling is crucial, as inadequate practices can lead to cross-contamination at any stage of the supply chain. To improve fish quality, effective handling techniques must be applied. The use of appropriate equipment and facilities, such as cool boxes, refrigerated or insulated trucks, and boats loaded with ice, enhances the transport of fish. Improved transport methods offer several benefits to stakeholders in the fisheries sector. Consumers may be exposed to bacterial pathogens due to poor handling, washing with polluted water, or ingestion of raw or inadequately cooked fish. While most pathogens can be eliminated through adequate cooking and control measures at each stage of the supply chain, exposure to raw or undercooked fish poses a serious risk to consumer health. [ABSTRACT FROM AUTHOR]

Macroalgae are beneficial for consumers and producers due to their high productivity, their chemical composition and their efficient cultivation without additional feed. Asia dominates global macroalgae production, while European production is still marginal and mainly based on wild harvesting in the North Atlantic. The European Commission has launched initiatives to promote the sustainable production, safe consumption and innovative use of macroalgae products in European regional seas, including the Mediterranean Sea. A variety of coastal and seabed types and a wide range of environmental conditions make the Mediterranean a hotspot of marine biodiversity while providing good conditions for the cultivation of macroalgae. The aim of this paper is to compare the global macroalgae production and macroalgae production in the Mediterranean Sea, focussing on the cultivation of edible macroalgae. The paper also discusses the limitations and possibilities of macroalgae production in the region. Macroalgae production is one of the most promising sectors of the blue economy in the Mediterranean. The production of edible macroalgae suitable for human consumption has great potential, considering future population growth and related food security and health issues, as well as the additional ecosystem benefits of macroalgae production. [ABSTRACT FROM AUTHOR]

The efficiency of pistachio nuts was investigated on the multiplication of Ectomyelois ceratoniae (Zeller) (Lep: Pyralidae) by rearing a cohort of 61 eggs individually at 26 ± 1 ℃, 60 ± 10% RH, and 16:8 h L:D. The age-stage two-sex life table theory and bootstrapping were used to analyze the data. The survival probability from a newly born egg to larva, pupa, and male and female adults was 0.77, 0.52, and 0.26 and 0.24, respectively. The total immature duration of males (45.33 d) was significantly shorter than that of females (49.47 d). The mean female fecundity was 98.08 eggs/fertile female (n = 12) and 78.46 eggs/all females (n = 15), respectively. The life expectancy of a newborn E. ceratoniae was 34.83 d, and the reproductive value was 79.63 at age 49 d of the female. Female moths had slightly longer longevity (7.82 d) compared with males (7.58 d). The population parameters R0, r, and λ were 19.29 offspring, 0.0548 d−1, and 1.0563 d−1, respectively. When eggs are harvested and the discard age is 62 d, the maximum harvest rate is 0.9481. Therefore, for a daily harvest of 10,000 eggs, the daily recruits of 547 eggs, 421 larvae, 287 pupae, 134 females, and 143 males are required in a stable stage structure rearing system. Each larva damaged and fed upon 2 gr. of raw pistachio to complete its development. Consequently, about 842 gr. pistachio nuts must be provided daily to meet the larval feeding demand, which imposes a cost of about $10 (local retail price) to the rearing system as nutritional provision. [ABSTRACT FROM AUTHOR]

From the perspective of ecological control, harvesting behavior plays a crucial role in the ecosystem natural cycle. This paper proposes a diffusive predator-prey system with predator harvesting to explore the impact of harvesting on predatory ecological relationships. First, the existence and boundedness of system solutions were investigated and the non-existence and existence of nonconstant steady states were obtained. Second, the conditions for Turing instability were given to further investigate the Turing patterns. Based on these conditions, the amplitude equations at the threshold of instability were established using weakly nonlinear analysis. Finally, the existence, direction, and stability of Hopf bifurcation were proven. Furthermore, numerical simulations were used to confirm the correctness of the theoretical analysis and show that harvesting has a strong influence on the dynamical behaviors of the predator-prey systems. In summary, the results of this study contribute to promoting the research and development of predatory ecosystems. [ABSTRACT FROM AUTHOR]

The North China Plain and the agricultural region are crossed by the Shanxi-Beijing natural gas pipeline. Residents in the area use rototillers for planting and harvesting; however, the depth of the rototillers into the ground is greater than the depth of the pipeline, posing a significant threat to the safe operation of the pipeline. Therefore, it is of great significance to study the dynamic response of rotary tillers impacting pipelines to ensure the safe operation of pipelines. This article focuses on the Shanxi-Beijing natural gas pipeline, utilizing finite element simulation software to establish a finite element model for the interaction among the machinery, pipeline, and soil, and analyzing the dynamic response of the pipeline. At the same time, a decision tree model is introduced to classify the damage of pipelines under different working conditions, and the boundary value and importance of each influencing factor on pipeline damage are derived. Considering the actual conditions in the hemp yam planting area, targeted management measures have been proposed to ensure the operational safety of the Shanxi-Beijing natural gas pipeline in this region. [ABSTRACT FROM AUTHOR]

This study evaluated the coagulation/flocculation process using chitosan as a natural coagulant to concentrate suspensions of the cyanobacterium Synechococcus subsalsus and enable biogas production from concentrated biomass. The chitosan performance was tested and compared with the inorganic ferric chloride (FeCl3) coagulant. Using the liquid fraction of the coagulation/flocculation process in subsequent biomass cultivations proved viable, with similar growths in culture media with up to 80% of the liquid fraction. At pH 6 and 400 mg/L FeCl3, the biomass concentrated almost seven times, increasing the total suspended solids (TSS) of the suspension from 0.4–0.6 g/L to 2.6–4.0 g/L. With 80 mg/L chitosan and pH 7, the TSS concentration attained values in the range of 7.0–9.7 g/L, an increase of more than 30 times, clearly showing that chitosan has a much higher capacity for biomass concentration at a lower concentration. A ratio of 0.3 g chitosan/g dry mass of the biomass was established to reach the maximum densification. The production of methane from chitosan-densified biomass proved to be feasible. Chitosan-densified biomass showed a two-phase cumulative methane production when digested, with slower methane production and 23% lower methane yield after 30 days of digestion (207 NmL CH4/g CODi) compared to the biomass from cultivation (non-densified, 270 NmL CH4/g CODi). However, optimizing the digestion conditions of the densified biomass should increase the methane yield and reduce process time. [ABSTRACT FROM AUTHOR]

RGB LED bulbs have entered the market as a promising alternative to traditional phosphor-coating LEDs to meet illumination standards. In this article, we introduce and propose solutions to address the challenges of RGB LED lighting for the Internet of Things applications, performing communication, harvesting energy, and sensing tasks. Through experiments, we demonstrate that we can use RGB LEDs for multiple tasks. We can achieve a bandwidth in the order of 50 kHz and distances of around 3.5 m using commercial RGB LED bulbs as transceivers, without using any dedicated photodetector. RGB LED links are composed of three main colors, and we show that red is the best color both for communicating to another receiving RGB LED bulb, as well as for harvesting with a solar cell; green and blue can instead be exploited for standard-compliant lighting and/or sensing purposes. We evaluate the system in two proofs of concept and provide insights for operating RGB LEDs for multiple tasks including vertical farming. [ABSTRACT FROM AUTHOR]