3,939 research outputs found
THE CHINESE ARE COMING – AN ANALYSIS OF THE PREFERENCES OF CHINESE HOLIDAY MAKERS AT HOME AND ABROAD
We analyse the destination choice of Chinese tourists in China and abroad. Abroad, Chinese tourists prefer to travel to large and rich countries, and are little deterred by distance. Climate, coast, culture and political stability are irrelevant. Chinese tourists travel disproportionally to “approved destinations”, but this is being eroded as more countries acquire this status. The model predicts that Southeast Asian countries are harmed most by the extension of the ADS system, while North America suffers most from being excluded. Domestically, Chinese tourists prefer rich and densely population areas, but dislike cities. They value easy access by road and rail, and are attracted by nature. Cultural attractions are less important, and may even reduce tourist numbers. Although potential tourist numbers are large, tourist operators should not assume that Chinese tourists behave like other tourists.International tourism, domestic tourism, China, destination choice
The impact of weather variability and climate change on pesticide applications in the US - An empirical investigation
Weather variability and climate change affect the application of pesticides in agriculture, in turn impacting the environment. Using panel data regression for the US, we find that weather and climate differences significantly influence the application rates of most pesticides. Subsequently, the regression results are linked to downscaled climate change scenario the Canadian and Hadley climate change models. We find that the application of most pesticides increase under both scenarios. The projection results vary by crop, region, and pesticide.Climate change, weather variability, pesticide, regression, panel data, North America, US
Economic impacts of changes in fish population dynamics: the role of the fishermen’s harvesting strategies
Using a bioeconomic model of the cod (Gadus morhua) and capelin (Mallotus villosus) fisheries of the Barents Sea, this study assesses the role of the fishermen’s behavior in reducing or intensifying the effects on the stocks caused by altered population dynamics. The analysis focuses on the economic development of the fisheries employing a profit-maximizing harvesting strategy over a given number of fishing periods. The scenarios assessed cover a time period of 100 years with sudden changes of the productivity of both species occurring at the midpoint of each simulation. Stock sizes and landings of fish are determined for each fishing period, and the net present values of profits over periods of interest prior to and following the change in population dynamics are calculated. Results show that if the profit-maximizing harvesting strategy is based on a short optimization period, the fleets with the higher efficiency are generally favored. If the strategy is based on an optimization over two or more fishing periods, fishing activities may be deferred to allow for stock regrowth. In such cases, smaller and less cost-intensive vessels are preferred. A reduction of either the productivity or the carrying capacities of the two species has little impact on the fisheries if the change is fairly small. A substantial reduction of either quantity has a lasting negative economic impact which mainly manifests itself in a severely reduced profitability of mainly the cod fishery.bioeconomic modeling, Barents Sea, cod, capelin, population dynamics, harvesting strategy
Rebuilding the Eastern Baltic cod stock under environmental change - Part II: The economic viability of a marine protected area
This study adds a cost analysis of the Eastern Baltic cod fishery to the existing model presented in Röckmann et al. (forthcoming). As cost data on this international fishery do not exist, available data from Denmark are extrapolated to the whole international fishery. Additionally, unit and total variable costs are simulated and the sensitivity to a set of different cost-stock and cost-output elasticities is tested. The study supports preliminary conclusions that a temporary marine reserve policy, which focuses on protecting the Eastern Baltic cod spawning stock in ICES subdivision 25, is a valuable fisheries management tool to (a) rebuild the overexploited Eastern Baltic cod stock and (b) increase operating profits. The negative effects of climate change can be postponed for at least 20 years – depending on the assumed rate of future climate change. Including costs in the economic analysis does not change the ranking of management policies as proposed in the previous study where costs were neglected.Development, Baltic cod, cost-stock elasticity, cost-output elasticity, sensitivity analysis, climate change scenario, management, policy, temporal marine reserve
Rebuilding the Eastern Baltic cod stock under environmental change - a preliminary approach using stock, environmental, and management constraints
The population dynamics of the Eastern Baltic cod (Gadus morhua callarias L.), unlike many other stocks, shows a strong dependency on environmental conditions. To test the implications of different management policies on the stock and the fishery in a system of global environmental change, we apply a spatially disaggregated, discrete time, age-structured model of the Eastern Baltic cod stock in 50 year simulation analyses. The simulation provides an analysis of stock, yield, and revenue development under various management policies and environmental scenarios. The policy analysis, focusing on different regulations of fishing mortality, is embedded into three environmental scenarios, assuming low, medium, or high climate and environmental change. The environmental assumptions are based on simulation results from a coupled atmosphere-ocean regional climate model, which project salinity in the Baltic Sea to decrease by 7-47% in the period 2071-2100 relative to the reference period 1961-1990. Our simulation results show that a significant reduction in fishing mortality is necessary for achieving high long-term economic yields. Moreover, under the presented environmental scenarios, a stock collapse cannot be prevented. It can, however, be postponed by the establishment of a marine reserve in ICES subdivision 25.Baltic cod, climate change, environmental variability, reproductive volume, population dynamics, management, policy, age-structured model, temporal marine reserve
Dzyaloshinsky-Moriya interaction in vesignieite: A route to freezing in a quantum kagome antiferromagnet
We report an electron spin resonance investigation of the geometrically
frustrated spin-1/2 kagome antiferromagnet vesignieite,
BaCuVO(OH). Analysis of the line widths and line shifts
indicates the dominance of in-plane Dzyaloshinsky-Moriya anisotropy that is
proposed to suppress strongly quantum spin fluctuations and thus to promote
long-range ordering rather than a spin-liquid state. We also evidence an
enhanced spin-phonon contribution that might originate from a lattice
instability and discuss the origin of a low-temperature mismatch between
intrinsic and bulk susceptibility in terms of local inhomogeneity
Symmetric and antisymmetric exchange anisotropies in quasi-one-dimensional CuSeO as revealed by ESR
We present an electron spin resonance (ESR) study of single-crystalline spin
chain-system CuSeO in the frequency range between 9 GHz and 450 GHz. In
a wide temperature range above the N\'{e}el temperature K we observe
strong and anisotropic frequency dependence of a resonance linewidth. Although
sizeable interchain interaction ( is the intrachain
interaction) is present in this system, the ESR results agree well with the
Oshikawa-Affleck theory for one-dimensional Heisenberg antiferromagnet.
This theory is used to extract the anisotropies present in CuSeO. We
find that the symmetric anisotropic exchange and the
antisymmetric Dzyaloshinskii-Moriya (DM) interaction are
very similar in size in this system. Staggered-field susceptibility induced by
the presence of the DM interaction is witnessed in the macroscopic
susceptibility anisotropy.Comment: 8 pages, 7 figures, 2 tables, published in Phys. Rev.
Testing the implications of a permanent or seasonal marine reserve on the population dynamics of Eastern Baltic cod under varying environmental conditions
In order to test the implications of the establishment of a marine reserve in the Baltic Sea, a spatially disaggregated, discrete time, age-structured model for the Eastern Baltic cod (Gadus morhua callarias L.) stock was constructed. Functional relationships for recruitment and predation mortality were developed by multiple regression analyses. The resultant model output compares well with observed data from the fishery. The model was then applied to simulate stock development over a 50 year time period using different management policies and a variety of environmental conditions. The investigated management policies reduce fishing mortality and range from a moratorium on the Eastern Baltic cod fishery via the establishment of a permanent or a seasonal marine reserve in ICES subdivision 25 to a fishing as usual scenario. The environmental conditions incorporated were based on the size of the reproductive volume (RV) and comprise a best case and a worst case of reproductive conditions, and two more realistic scenarios, where we assumed that a historic series of RV-sizes reoccurs over the simulation period. Our results show a strong dependence of stock dynamics on the environmental conditions. Under prevailing low RV, our model projects stock extinction by the year 2020, if fishing continues as usual. Under the restrictive scenarios, where fishing mortality is reduced either directly or by implementation of a marine reserve, the stock benefits from an increase in stock size and an improved age-structure. A seasonal closure of SD 25 as opposed to a closure of the entire Baltic Sea appears to be sufficient to prevent the Eastern Baltic cod stock from falling below safe biological limits.Baltic cod, management, age-structured model, population dynamics, MPA, environmental variability, reproductive volume
Quenching Spin Decoherence in Diamond through Spin Bath Polarization
We experimentally demonstrate that the decoherence of a spin by a spin bath
can be completely eliminated by fully polarizing the spin bath. We use electron
paramagnetic resonance at 240 gigahertz and 8 Tesla to study the spin coherence
time of nitrogen-vacancy centers and nitrogen impurities in diamond from
room temperature down to 1.3 K. A sharp increase of is observed below the
Zeeman energy (11.5 K). The data are well described by a suppression of the
flip-flop induced spin bath fluctuations due to thermal spin polarization.
saturates at below 2 K, where the spin bath polarization
is 99.4 %.Comment: 5 pages and 3 figure
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