38 research outputs found
Various Correlations in Anisotropic Heisenberg XYZ Model with Dzyaloshinski-Moriya Interaction
Various thermal correlations as well as the effect of intrinsic decoherence
on the correlations are studied in a two-qubit Heisenberg XYZ spin chain with
the Dzyaloshinski--Moriya (DM) interaction along the z direction, i.e. Dz. It
is found that tunable parameter Dz may play a constructive role on the
concurrence (C), classical correlation (CC) and quantum discord (QD) in thermal
equilibrium while it plays a destructive role on the correlations in the
intrinsic decoherence case. The entanglement and quantum discord exhibit
collapse and revival under the phase decoherence. With a proper combination of
the system parameters, the correlations can effectively be kept at high steady
state values despite the intrinsic decoherence.Comment: 4 pages, 4 figure
Characteristics and difficulties of semi-nomadic livestock economy in Yili area, Xinjiang, China
Air pollution and meteorological processes in the growing dryland city of Urumqi (Xinjiang, China)
Use of laboratory and remote sensing techniques to estimate vegetation patch scale emissions of nitric oxide from an arid Kalahari savanna
Use of laboratory and remote sensing techniques to estimate vegetation patch scale emissions of nitric oxide from an arid Kalahari savanna
Soil biogenic emissions of nitric oxide from a semi-arid savanna in South Africa
Soils of arid and semi-arid ecosystems are important biogenic sources of atmospheric nitric oxide (NO), however, there is still a shortage of measurements from these systems. Here we present the results of a laboratory study of the biogenic emission of NO from four different landscape positions of the Kruger National Park (KNP), a large conservation area in a semi-arid region of South Africa. Results show that the highest net potential NO fluxes come from the low lying (footslope) landscape regions, which have the largest nitrogen stocks and highest rates of nitrogen input into the soil. Net potential NO fluxes from midslope and crest regions were considerably lower. The maximum release of NO occurred at fairly low soil moisture contents of 10%–20% water filled pore space. Using soil moisture and temperature data obtained in situ at the Kruger National Park flux tower site, net potential NO fluxes obtained in the laboratory were converted to field fluxes for each of the four landscape positions for the period 2003 to 2005. The highest field NO flux is from footslope positions, during each of these years and emissions ranged from 1.5–8.5 kg ha a (in terms of mass of nitrogen). Remote sensing and Geographic Information Systems techniques were used to up-scale field NO fluxes on a regional basis indicating that the highest emissions occurred from the midslope positions, due to their large geographical extent in the considered research area. Emissions for the KNP Skukuza land type (56 000 ha) ranged from 20&times;10<sup>3</sup> kg in 2004 to 34&times;10<sup>3</sup> kg in 2003. The importance of landscape characteristics in the determination of regional biogenic NO soil emission is emphasized
The contribution of soil biogenic NO and HONO emissions from a managed hyperarid ecosystem to the regional NO<sub><i>x</i></sub> emissions during growing season
A study was carried out to understand the contributions of soil biogenic NO
emissions from managed (fertilized and irrigated) hyperarid ecosystems in
NW China to the regional NO<sub><i>x</i></sub> emissions during the growing season. Soil
biogenic net potential NO fluxes were quantified by laboratory incubation of
soil samples from the three dominating ecosystems (desert, cotton, and grape
fields). Regional biogenic NO emissions were calculated bottom-up hourly for
the entire growing season (April–September 2010) by considering
corresponding land use, hourly data of soil temperature, gravimetric soil
moisture, and fertilizer enhancement factors. The regional HONO emissions
were estimated using the ratio of the optimum condition
((<i>F</i><sub>N,<sub>opt</sub></sub>(HONO) to <i>F</i><sub>N,<sub>opt</sub></sub> (NO)).<br><br> Regional anthropogenic NO<sub><i>x</i></sub> emissions were calculated bottom-up from
annual statistical data provided by regional and local government bureaus
which have been downscaled to monthly value. Regional top-down emission
estimates of NO<sub><i>x</i></sub> were derived on the monthly basis from satellite
observations (OMI) of tropospheric vertical NO<sub>2</sub> column densities and
prescribed values of the tropospheric NO<sub><i>x</i></sub> lifetime. In order to compare
the top-down and bottom-up emission estimates, all emission estimates were
expressed in terms of mass of atomic nitrogen. Consequently, monthly
top-down NO<sub><i>x</i></sub> emissions (total) were compared with monthly bottom-up
NO<sub><i>x</i></sub> emissions (biogenic + anthropogenic) for the time of the
satellite overpass (around 13:00 LT) with the consideration of the diurnal
cycle of bottom-up estimates. Annual variation in total Tohsun Oasis
NO<sub><i>x</i></sub> emissions is characterized by a strong peak in winter
(December–February) and a secondary peak in summer (June–August). During
summer, soil biogenic emissions were from equal to double that of related
anthropogenic emissions, and grape soils were the main contributor to soil
biogenic emissions, followed by cotton soils, while emissions from the desert
were negligible. The top-down and bottom-up emission estimates were shown to
be useful methods to estimate the monthly/seasonal cycle of the total
regional NO<sub><i>x</i></sub> emissions. The resulting total NO<sub><i>x</i></sub> emissions show a
strong peak in winter and a secondary peak in summer, and the second maximum
in summer was only found if the soil emissions were taken into account,
which provides confidence in both completely independent methods. Despite
the regional character of these findings, particularly the second maximum in
summer provides substantial evidence to hypothesize that biogenic emissions
from soils of managed drylands (irrigated and fertilized) in the growing
period may be much more important contributors to regional NO<sub><i>x</i></sub> budgets
of dryland regions than thought before
The contribution of soil biogenic NO emissions from a managed hyper-arid ecosystem to the regional NO<sub>2</sub> emissions during growing season
A study was carried out to understand the contributions of soil biogenic NO emissions from managed (fertilized and irrigated) hyper-arid ecosystem in NW-China to the regional NO2 emissions during growing season. Soil biogenic NO emissions were 5 quantified by laboratory incubation of corresponding soil samples. We have developed the Geoscience General Tool Package (GGTP) to obtain soil temperature, soil moisture and biogenic soil NO emission at oasis scale. Bottom-up anthropogenic NO2 emissions have been scaled down from annual to monthly values to compare mean monthly soil biogenic NO2 emissions. The top-down emission estimates have been 10 derived from satellite observations compared then with the bottom-up emission estimates (anthropogenic and biogenic). The results show that the soil biogenic emissions of NO2 during the growing period are (at least) equal until twofold of the related anthropogenic sources. We found that the grape soils are the main summertime contributor to the biogenic NO emissions of study area, followed by cotton soils. The top-down 15 and bottom-up emission estimates were shown to be useful methods to estimate the monthly/seasonal cycle of the total regional NO2 emissions. The resulting total NO2 emissions show a strong peak in winter and a secondary peak in summer, providing confidence in the method. These findings provide strong evidence that biogenic emissions from soils of managed drylands (irrigated and fertilized) in the growing pe20 riod can be much more important contributors to the regional NO2 budget (hence to regional photochemistry) of dryland regions than thought before
The contribution of soil biogenic NO and HONO emissions from a managed hyperarid ecosystem to the regional NOx emissions during growing season
A study was carried out to understand the contributions of soil biogenic NO emissions from managed (fertilized and irrigated) hyperarid ecosystems in NW China to the regional NOx emissions during the growing season. Soil biogenic net potential NO fluxes were quantified by laboratory incubation of soil samples from the three dominating ecosystems (desert, cotton, and grape fields). Regional biogenic NO emissions were calculated bottom-up hourly for the entire growing season (April-September 2010) by considering corresponding land use, hourly data of soil temperature, gravimetric soil moisture, and fertilizer enhancement factors. The regional HONO emissions were estimated using the ratio of the optimum condition ((F-N,F-opt (HONO) to F-N,F-opt (NO)). Regional anthropogenic NOx emissions were calculated bottom-up from annual statistical data provided by regional and local government bureaus which have been downscaled to monthly value. Regional top-down emission estimates of NOx were derived on the monthly basis from satellite observations (OMI) of tropospheric vertical NO2 column densities and prescribed values of the tropospheric NOx lifetime. In order to compare the top-down and bottom-up emission estimates, all emission estimates were expressed in terms of mass of atomic nitrogen. Consequently, monthly top-down NOx emissions (total) were compared with monthly bottomup NOx emissions (biogenic C anthropogenic) for the time of the satellite overpass (around 13:00 LT) with the consideration of the diurnal cycle of bottom-up estimates. Annual variation in total Tohsun Oasis NOx emissions is characterized by a strong peak in winter (December-February) and a secondary peak in summer (June-August). During summer, soil biogenic emissions were from equal to double that of related anthropogenic emissions, and grape soils were the main contributor to soil biogenic emissions, followed by cotton soils, while emissions from the desert were negligible. The top-down and bottom-up emission estimates were shown to be useful methods to estimate the monthly/seasonal cycle of the total regional NOx emissions. The resulting total NOx emissions show a strong peak in winter and a secondary peak in summer, and the second maximum in summer was only found if the soil emissions were taken into account, which provides confidence in both completely independent methods. Despite the regional character of these findings, particularly the second maximum in summer provides substantial evidence to hypothesize that biogenic emissions from soils of managed drylands (irrigated and fertilized) in the growing period may be much more important contributors to regional NOx budgets of dryland regions than thought before