128 research outputs found
Spatial and temporal regeneration patterns within gaps in the primary forests vs. secondary forests of Northeast China
Forest gaps play an important role during forest succession in temperate forest ecosystems. However, the differences in spatial distribution and replacement patterns of woody plants (trees and shrubs) between primary and secondary forests remain unclear during the gap-filling processes, especially for temperate forests in Northeast China. We recorded 45,619 regenerated trees and shrubs in young gaps (<10 years), old gaps (10~20 years), and closed forest stands (i.e., filled gaps) in the primary broadleaved Korean pine (Pinus koraiensis Sieb. Rt Zucc.) forests vs. secondary forests (degraded from primary forests). The gap-filling processes along horizontal (Cartesian coordinate system) and vertical (lower layer: 0~5 m, medium layer: 5~10 m, and upper layer: >10Â m) dimensions were quantified by shade tolerance groups of trees and shrubs. We found that gap age, competition between species, and pre-existing regeneration status resulted in different species replacement patterns within gaps in primary vs. secondary forests. Gap formation in both primary and secondary forests increased species richness, with 33, 38, 39, and 41 in the primary closed stands, primary forest gaps, secondary closed stands, and secondary forest gaps, respectively. However, only 35.9% of species in primary forest gaps and 34.1% in secondary forest gaps successfully reached the upper layer. Based on the importance values (IVs) of tree species across different canopy heights, light-demanding trees in the upper layer of the secondary forests were gradually replaced by intermediate and shade-tolerant trees. In the primary forests, Korean pine exhibited intermittent growth patterns at different canopy heights, while it had continuous regeneration along vertical height gradients in the secondary forests. The differences in Korean pine regeneration between the primary and secondary forests existed before gap formation and continued during the gap-filling processes. The interspecific competition among different tree species gradually decreased with increasing vertical height, and compared to the primary forests, the secondary forests showed an earlier occurrence of competition exclusion within gaps. Our findings revealed the species replacement patterns within gaps and provided a further understanding of the competition dynamics among tree species during the gap-filling processes
Prognostic value of inflammatory nutritional scores in locally advanced esophageal squamous cell carcinoma patients undergoing neoadjuvant chemoimmunotherapy: a multicenter study in China
ObjectiveThis study investigates the prognostic significance of inflammatory nutritional scores in patients with locally advanced esophageal squamous cell carcinoma (LA-ESCC) undergoing neoadjuvant chemoimmunotherapy.MethodsA total of 190 LA-ESCC patients were recruited from three medical centers across China. Pre-treatment laboratory tests were utilized to calculate inflammatory nutritional scores. LASSO regression and multivariate logistic regression analyses were conducted to pinpoint predictors of pathological response. Kaplan-Meier and Cox regression analyses were employed to assess disease-free survival (DFS) prognostic factors.ResultsThe cohort comprised 154 males (81.05%) and 36 females (18.95%), with a median age of 61.4 years. Pathological complete response (pCR) was achieved in 17.38% of patients, while 44.78% attained major pathological response (MPR). LASSO and multivariate logistic regression analyses identified that hemoglobin, albumin, lymphocyte, and platelet (HALP) (P=0.02) as an independent predictors of MPR in LA-ESCC patients receiving neoadjuvant chemoimmunotherapy. Kaplan-Meier and log-rank tests indicated that patients with low HALP, MPR, ypT1-2, ypN0 and, ypTNM I stages had prolonged DFS (P < 0.05). Furthermore, univariate and multivariate Cox regression analyses underscored HALP (P = 0.019) and ypT (P = 0.029) as independent predictive factors for DFS in ESCC.ConclusionOur study suggests that LA-ESCC patients with lower pre-treatment HALP scores exhibit improved pathological response and reduced recurrence rate. As a comprehensive index of inflammatory nutritional status, pre-treatment HALP may be a reliable prognostic marker in ESCC patients undergoing neoadjuvant chemoimmunotherapy
Exportation of Monkeypox Virus From the African Continent.
BACKGROUND: The largest West African monkeypox outbreak began September 2017, in Nigeria. Four individuals traveling from Nigeria to the United Kingdom (n = 2), Israel (n = 1), and Singapore (n = 1) became the first human monkeypox cases exported from Africa, and a related nosocomial transmission event in the United Kingdom became the first confirmed human-to-human monkeypox transmission event outside of Africa. METHODS: Epidemiological and molecular data for exported and Nigerian cases were analyzed jointly to better understand the exportations in the temporal and geographic context of the outbreak. RESULTS: Isolates from all travelers and a Bayelsa case shared a most recent common ancestor and traveled to Bayelsa, Delta, or Rivers states. Genetic variation for this cluster was lower than would be expected from a random sampling of genomes from this outbreak, but data did not support direct links between travelers. CONCLUSIONS: Monophyly of exportation cases and the Bayelsa sample, along with the intermediate levels of genetic variation, suggest a small pool of related isolates is the likely source for the exported infections. This may be the result of the level of genetic variation present in monkeypox isolates circulating within the contiguous region of Bayelsa, Delta, and Rivers states, or another more restricted, yet unidentified source pool
Merging databases under constraints
The problem of integrating information from con icting sources comes up in many current applications, such as cooperative information systems, heterogeneous databases, and multi-agent systems. We model this by the operation of merging rst-order theories. We propose a formal semantics for this operation and show that it has desirable properties, including abiding by majority rule in case of con ict and syntax independence. We apply our semantics to the special case when the theories to be merged represent relational databases under integrity constraints. We then present away of merging databases that have di erent or con icting schemas caused by problems such as synonyms, homonyms or type con icts mentioned in the schema integration literature.
Knowledge Base Merging by Majority
A common practice for resolving conflicts among a group of agents is to let the majority decide. We formalize this principle and apply it to the problem of merging the knowledge of multiple agents. We then postulate logical properties that all knowledge merging operators should satisfy and give a model-theoretic characterization of all merging operators that satisfy the postulates. It turns out that the operators that satisfy the postulates are precisely those that induce a certain kind of partial pre-order over the set of possible worlds such that the models of the merged knowledge base are the possible worlds that are minimal with respect to the pre-order. Then, we review several previous approaches and study them in light of the proposed postulates. We then present a particular method for knowledge merging, CMerge, that satisfies all the postulates. We show by example that CMerge appears to resolve conflicts among knowledge bases in a plausible way. Finally, we show that CMerge can ..
A Requirement Ontology for Engineering Design
We present an ontology for representing requirements that supports a generic requirements management process in engineering design domain. The requirement ontology we propose is a part of a more general ontology to capture engineering design knowledge. Objects included in the ontology are parts, features, requirements, and constraints. We define a generic requirements management process and raise issues that the ontology must address like communication, traceability, completeness, consistency, document creation, and managing change. We use first-order logic to define the objects and their attributes, and identify the axioms capturing the constraints and relationships among the objects. We show how the axioms can be used in answering many of these issues. 1 Introduction Requirements Management is one of the key elements that must be addressed by concurrent engineering (CE) [13]. Yet the representation and management of requirements is problematic in CE. Requirements are often ambiguo..
- …