169 research outputs found
Public's Willingness to Pay for Ecosystem Service Improvements From Agriculture
Consumer/Household Economics, Demand and Price Analysis,
The herpetofauna of Iwokrama reserve: a comparison of sampling methods
Inventory sampling provides information on assemblage structure and baseline species diversity data for future comparisons. This study explored the efficiency and accuracy of inventory sampling methods for an assemblage of lowland tropical amphibians and reptiles. Data were collected from the Iwokrama International Centre for Rain Forest Conservation and Development in Guyana. Four standard methods (day visual encounter survey, night visual encounter survey, leaf litter plots, and opportunistic collecting) were used to examine assemblage structure. I analyzed these data to look for variation in amphibian and reptile species diversity among different parts of the reserve and different methods. Species diversity varied among the different populations sampled in terms o f species richness. Estimations in species richness also varied among methods. Night visual encounter surveys provided the highest average number of individuals and species caught per person-hour of effort. However, a combination of methods portrayed the most accurate species richness within the reserve
Comparison of Three Different Styles of Submarine Sails on Electromagnetic Scattering under the Detection of Airborne Radar
This paper studies radar cross section of submarine sails on the water. Under the detection of the enemy’s airborne radar, considering the motion of the submarine, the sail model of radar pitch angle incidence range analysis is established. By using CATIA software, the 3D models of AKULA sail, SUBOFF sail and VICTOR sail are built. On the basis of the physical optics method and the equivalent currents method, the scattering characteristics of sails RCS(radar cross section) are simulated under X radar band. Through the microwave anechoic chamber test, this paper verifies the accuracy of the combination of the physical optics method and the equivalent electromagnetic flow method. The influence of the distance from the airborne radar to the sail on the pitch angle of the electromagnetic wave is discussed, with the elevation angle of the radar antenna varies. Then, we illustrate the characteristics of circumferential direction RCS of the sail under different pitch angles. Finally, the mean RCS of the sail at a given pitch angle is simulated. The results show that the AKULA sail is considerably superior to SUBOFF sail and VICTOR sail on stealth performance with the pitch angle less than 4° . But when the pitch angle exceeds 10°, the SUBOFF sail can be given priority
ALIX binds a YPX(3)L motif of the GPCR PAR1 and mediates ubiquitin-independent ESCRT-III/MVB sorting.
The sorting of signaling receptors to lysosomes is an essential regulatory process in mammalian cells. During degradation, receptors are modified with ubiquitin and sorted by endosomal sorting complex required for transport (ESCRT)-0, -I, -II, and -III complexes into intraluminal vesicles (ILVs) of multivesicular bodies (MVBs). However, it remains unclear whether a single universal mechanism mediates MVB sorting of all receptors. We previously showed that protease-activated receptor 1 (PAR1), a G protein-coupled receptor (GPCR) for thrombin, is internalized after activation and sorted to lysosomes independent of ubiquitination and the ubiquitin-binding ESCRT components hepatocyte growth factor-regulated tyrosine kinase substrate and Tsg101. In this paper, we report that PAR1 sorted to ILVs of MVBs through an ESCRT-III-dependent pathway independent of ubiquitination. We further demonstrate that ALIX, a charged MVB protein 4-ESCRT-III interacting protein, bound to a YPX(3)L motif of PAR1 via its central V domain to mediate lysosomal degradation. This study reveals a novel MVB/lysosomal sorting pathway for signaling receptors that bypasses the requirement for ubiquitination and ubiquitin-binding ESCRTs and may be applicable to a subset of GPCRs containing YPX(n)L motifs
A low-degree strictly conservative finite element method for incompressible flows on general triangulations
Diagonal Sums of Doubly Substochastic Matrices
Let Ωn denote the convex polytope of all n x n doubly stochastic matrices, and ωn denote the convex polytope of all n x n doubly substochastic matrices. For a matrix A ϵ ωn, define the sub-defect of A to be the smallest integer k such that there exists an (n + k) x (n + k) doubly stochastic matrix containing A as a submatrix. Let ωn,k denote the subset of ωn which contains all doubly substochastic matrices with sub-defect k. For π a permutation of symmetric group of degree n, the sequence of elements a1π(1); a2π(2), ..., anπ(n) is called the diagonal of A corresponding to π. Let h(A) and l(A) denote the maximum and minimum diagonal sums of A ϵ ωn,k, respectively. In this paper, existing results of h and l functions are extended from Ωn to ωn,k. In addition, an analogue of Sylvesters law of the h function on ωn,k is proved
The relationship between work–family conflict and job satisfaction for preschool teachers in rural China: a moderated mediation model
BackgroundJob satisfaction for preschool teachers in rural areas has an important impact on their professional development, physical and mental health, and the development of preschool education. However, few studies have explored the factors that influence rural preschool teachers’ job satisfaction.PurposeThis study aims to examine the influence of rural preschool teachers’ work–family conflict on their job satisfaction, and the mediating effect of occupational identity, the moderating effect of social support.MethodParticipants included 3,065 rural preschool teachers from Zhejiang Province in mainland China. Teachers completed questionnaires on work–family conflict, occupational identity, job satisfaction, and social support. The correlation and moderated mediation analyses were conducted using SPSS PROCESS.Results(1) work–family conflict is associated with poorer job satisfaction in preschool teachers; (2) occupational identity mediates the relationship between work–family conflict and job satisfaction; and (3) a high level of social support alleviates the negative influence of work–family conflict on job satisfaction and promotes the positive effect of occupational identity on job satisfaction.ConclusionThe study revealed the negative impact of work–family conflict on preschool teachers’ job satisfaction, and the protecting effect of social support, which has important implications for improving teachers’ future job satisfaction
The impact of knowledge governance mechanisms on supply chain performance: Empirical evidence from the agri-food industry
The agri-food supply chain (AFSC) is an extremely complex structure that comprises a series of events from farm-to-fork. Additionally, there is a wide range of information and material flows required to be managed, which are seen as the knowledge flow in the AFSCs. It is expected that the use of knowledge governance mechanisms (KGMs) will help in enhancing AFSC performance. To examine the impact of KGMs on AFSC performance, a mixed methods research design was applied. First, semi-structured interviews were conducted to collect data. Then, themes were generated through thematic analysis. Afterwards, relationships between KGMs and AFSC performance were built by using total interpretive structural modelling (TISM). Finally, questionnaire-based structured interviews were undertaken to evaluate the empirical and theoretical findings further. The research results indicate that trust-, reciprocity-, market-, and contract-based KGMs have positive effects on product quality, efficiency, flexibility, responsiveness, and process quality of AFSC. Furthermore, market-based KGM, located in the lowest level in the TISM hierarchy, should be given additional focus due to its role as a key force driving the higher level of AFSC performance and other KGMs. The findings provide AFSC practitioners with useful guidance on how the relationships between KGMs and AFSC performance should be managed to improve the performance of AFSC
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