13,532 research outputs found
Recovery of Listonella anguillarum from Diseased Pufferfish (Takifugu rubripes) in China
In May 2016, there was a disease outbreak among pufferfish (Takifugu
rubripes) in a marine farm in Tianjin municipality, with the cumulative
mortality rate reaching 45% within 7 days from the beginning of the
outbreak. The main symptoms of the disease were abdominal and anal
swelling of the diseased fish. Significant damage was also observed
histopathologically in the intestine, liver, and kidney. The strain H008 was
isolated from diseased kidneys, and the challenge test revealed that the same
disease was diagnosed in pufferfish which suffered similarly high mortality
rates. Using physiological biochemical tests combined with 16S rDNA
sequence analysis, the strain was identified as Listonella anguillarum.
Antimicrobial susceptibility tests showed that H008 was resistant to 10 of 15
antimicrobial agents tested. To the best of our knowledge, this is the first
report of L. anguillarum causing disease in pufferfish
Drought events and their effects on vegetation productivity in China
Many parts of the world have experienced frequent and severe droughts during the last few decades. Most previous studies examined the effects of specific drought events on vegetation productivity. In this study, we characterized the drought events in China from 1982 to 2012 and assessed their effects on vegetation productivity inferred from satellite data. We first assessed the occurrence, spatial extent, frequency, and severity of drought using the Palmer Drought Severity Index (PDSI). We then examined the impacts of droughts on China\u27s terrestrial ecosystems using the Normalized Difference Vegetation Index (NDVI). During the period 1982â2012, China\u27s land area (%) experiencing drought showed an insignificant trend. However, the drought conditions had been more severe over most regions in northern parts of China since the end of the 1990s, indicating that droughts hit these regions more frequently due to the drier climate. The severe droughts substantially reduced annual and seasonal NDVI. The magnitude and direction of the detrended NDVI under drought stress varied with season and vegetation type. The inconsistency between the regional means of PDSI and detrended NDVI could be attributed to different responses of vegetation to drought and the timing, duration, severity, and lag effects of droughts. The negative effects of droughts on vegetation productivity were partly offset by the enhancement of plant growth resulting from factors such as lower cloudiness, warming climate, and human activities (e.g., afforestation, improved agricultural management practices)
Toward Sustainable Construction: Optimizing Carbon Emission Reduction in the Building Supply Chain through Game-Theoretic Strategies, Government Subsidies, and Cost-Sharing Contract
The carbon emission reduction (CER) in the construction industry can aid in achieving the international community's carbon neutrality target. However, the low motivation of construction enterprises to reduce carbon emissions and the unsatisfactory effect of CER are still unresolved issues. This study aims to address these issues by constructing a building supply chain (BSC) consisting of a developer and a contractor using government subsidies and cost-sharing contracts. The optimal government subsidy and feedback equilibrium strategies of the BSC are examined using a combination of differential game theory and numerical simulations. The findings demonstrate that (1) Cost-sharing contracts may enhance developer and contractor profits and building CER, goodwill, and demand without relying on government subsidies. (2) When subsidized by the government, each equilibrium strategy meets or exceeds the performance of the centralized model, with the cost-sharing contract having a negligible effect on the enhancement of each equilibrium strategy. (3) Both the game structure and the positioning of construction enterprises in the BSC are connected to the number of government subsidies. The city of Shenzhen, one of China's first low-carbon pilot cities, provides a realistic environment for the simulation analysis, with the Block K residential building in Nanshan District serving as a case study. Furthermore, this work contributes to the body of knowledge by proposing a novel CER model for the BSC using differential game theory. The research provides new insights into the role of government subsidies in shaping profit distribution, game structure, and enterprise positioning. Findings demonstrate the value of cost-sharing contracts in improving CER, goodwill, demand, and profits when implemented collaboratively. This advances the theoretical understanding of incentives and strategies for promoting CER in construction.
Practical applications:
This research highlights the importance of collaborative efforts between the government and the BSC to promote sustainable construction and CER. The study found that government subsidies can be an effective tool to encourage developers and contractors to adopt CER practices. However, relying solely on subsidies is insufficient - collaboration through mechanisms like cost-sharing contracts can further enhance sustainability outcomes when enterprises work together. To facilitate low-carbon construction, the government could provide subsidies for developers' promotional and marketing activities as well as funding for contractors' research and development of sustainable materials and technologies. Financial incentives like tax breaks and preferential lending for potential homebuyers can also accelerate consumer demand. Ultimately, creating a supportive environment where enterprises proactively pursue CER creates a win-win situation - the BSC becomes more sustainable while firms improve their branding and profitability. The insights from this research highlight the need for a multi-pronged approach. Governments play a key role through policy and financial support. Realizing the full potential of sustainable construction also requires active participation from developers, contractors, and consumers. By outlining optimal strategies and incentives, this study provides valuable guidance to construction industry stakeholders seeking to implement CER collaboratively
Cosmological dynamics of scalar fields with O(N) symmetry
In this paper, we study the cosmological dynamics of scalar fields with O(N)
symmetry in general potentials. We compare the phase space of the dynamical
systems of the quintessence and phantom and give the conditions for the
existence of various attractors as well as their cosmological implications. We
also show that the existence of tracking attractor in O(N) phantom models
require the potential with , which makes the models with
exponential potential possess no tracking attractor.Comment: 9 pages, 4 figures; Replaced with the version to be published in
Classical and Quantum Gravity. Reference adde
Beyond Counting: New Perspectives on the Active IPv4 Address Space
In this study, we report on techniques and analyses that enable us to capture
Internet-wide activity at individual IP address-level granularity by relying on
server logs of a large commercial content delivery network (CDN) that serves
close to 3 trillion HTTP requests on a daily basis. Across the whole of 2015,
these logs recorded client activity involving 1.2 billion unique IPv4
addresses, the highest ever measured, in agreement with recent estimates.
Monthly client IPv4 address counts showed constant growth for years prior, but
since 2014, the IPv4 count has stagnated while IPv6 counts have grown. Thus, it
seems we have entered an era marked by increased complexity, one in which the
sole enumeration of active IPv4 addresses is of little use to characterize
recent growth of the Internet as a whole.
With this observation in mind, we consider new points of view in the study of
global IPv4 address activity. Our analysis shows significant churn in active
IPv4 addresses: the set of active IPv4 addresses varies by as much as 25% over
the course of a year. Second, by looking across the active addresses in a
prefix, we are able to identify and attribute activity patterns to network
restructurings, user behaviors, and, in particular, various address assignment
practices. Third, by combining spatio-temporal measures of address utilization
with measures of traffic volume, and sampling-based estimates of relative host
counts, we present novel perspectives on worldwide IPv4 address activity,
including empirical observation of under-utilization in some areas, and
complete utilization, or exhaustion, in others.Comment: in Proceedings of ACM IMC 201
Concept coupling learning for improving concept lattice-based document retrieval
© 2017 Elsevier Ltd The semantic information in any document collection is critical for query understanding in information retrieval. Existing concept lattice-based retrieval systems mainly rely on the partial order relation of formal concepts to index documents. However, the methods used by these systems often ignore the explicit semantic information between the formal concepts extracted from the collection. In this paper, a concept coupling relationship analysis model is proposed to learn and aggregate the intra- and inter-concept coupling relationships. The intra-concept coupling relationship employs the common terms of formal concepts to describe the explicit semantics of formal concepts. The inter-concept coupling relationship adopts the partial order relation of formal concepts to capture the implicit dependency of formal concepts. Based on the concept coupling relationship analysis model, we propose a concept lattice-based retrieval framework. This framework represents user queries and documents in a concept space based on fuzzy formal concept analysis, utilizes a concept lattice as a semantic index to organize documents, and ranks documents with respect to the learned concept coupling relationships. Experiments are performed on the text collections acquired from the SMART information retrieval system. Compared with classic concept lattice-based retrieval methods, our proposed method achieves at least 9%, 8% and 15% improvement in terms of average MAP, IAP@11 and P@10 respectively on all the collections
CMBR Constraint on a Modified Chaplygin Gas Model
In this paper, a modified Chaplygin gas model of unifying dark energy and
dark matter with exotic equation of state
which can also explain the recent accelerated expansion of the universe is
investigated by the means of constraining the location of the peak of the CMBR
spectrum. We find that the result of CMBR measurements does not exclude the
nonzero value of parameter , but allows it in the range .Comment: 4 pages, 3 figure
Mott-Kondo Insulator Behavior in the Iron Oxychalcogenides
We perform a combined experimental-theoretical study of the
Fe-oxychalcogenides (FeO\emph{Ch}) series
LaOFeO\emph{M} (\emph{M}=S, Se), which is the latest
among the Fe-based materials with the potential \ to show unconventional
high-T superconductivity (HTSC). A combination of incoherent Hubbard
features in X-ray absorption (XAS) and resonant inelastic X-ray scattering
(RIXS) spectra, as well as resitivity data, reveal that the parent
FeO\emph{Ch} are correlation-driven insulators. To uncover microscopics
underlying these findings, we perform local density
approximation-plus-dynamical mean field theory (LDA+DMFT) calculations that
unravel a Mott-Kondo insulating state. Based upon good agreement between theory
and a range of data, we propose that FeO\emph{Ch} may constitute a new, ideal
testing ground to explore HTSC arising from a strange metal proximate to a
novel selective-Mott quantum criticality
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