The prolonged drought of recent years combined with the steadily increasing bark beetle infestation (Ips typographus) is causing enormous damage in Germany’s spruce forests. This preliminary study ...investigates whether early spruce infestation by the bark beetle (green attack) can be detected using indices based on airborne spatial high-resolution (0.3 m) hyperspectral data and field spectrometer measurements. In particular, a new hyperspectral index based on airborne data has been defined and compared with other common indices for bark beetle detection. It shows a very high overall accuracy (OAA = 98.84%) when validated with field data. Field measurements and a long-term validation in a second study area serve the validation of the robustness and transferability of the index to other areas. In comparison with commonly used indices, the defined index has the ability to detect a larger proportion of infested spruces in the green attack phase (60% against 20% for commonly used indices). This index confirms the high potential of the red-edge domain to distinguish infested spruces at an early stage. Overall, our index has great potential for forest preservation strategies aimed at the detection of infested spruces in order to mitigate the outbreaks.
Forests’ ecosystems are an essential part of the global carbon cycle with vast carbon storage potential. These systems are currently under external pressures showing increasing change due to climate ...change. A better understanding of the biophysical properties of forests is, therefore, of paramount importance for research and monitoring purposes. While there are many biophysical properties, the focus of this study is on the in-depth analysis of the connection between the C-band Copernicus Sentinel-1 SAR backscatter and evapotranspiration (ET) estimates based on in situ meteorological data and the FAO-based Penman–Monteith equation as well as the well-established global terrestrial ET product from the Terra and Aqua MODIS sensors. The analysis was performed in the Free State of Thuringia, central Germany, over coniferous forests within an area of 2452 km2, considering a 5-year time series (June 2016–July 2021) of 6- to 12-day Sentinel-1 backscatter acquisitions/observations, daily in situ meteorological measurements of four weather stations as well as an 8-day composite of ET products of the MODIS sensors. Correlation analyses of the three datasets were implemented independently for each of the microwave sensor’s acquisition parameters, ascending and descending overpass direction and co- or cross-polarization, investigating different time series seasonality filters. The Sentinel-1 backscatter and both ET time series datasets show a similar multiannual seasonally fluctuating behavior with increasing values in the spring, peaks in the summer, decreases in the autumn and troughs in the winter months. The backscatter difference between summer and winter reaches over 1.5 dB, while the evapotranspiration difference reaches 8 mm/day for the in situ measurements and 300 kg/m2/8-day for the MODIS product. The best correlation between the Sentinel-1 backscatter and both ET products is achieved in the ascending overpass direction, with datasets acquired in the late afternoon, and reaches an R2-value of over 0.8. The correlation for the descending overpass direction reaches values of up to 0.6. These results suggest that the SAR backscatter signal of coniferous forests is sensitive to the biophysical property evapotranspiration under some scenarios.
We demonstrate optical tuning of the scattering length in a Bose-Einstein condensate as predicted by Fedichev et al. Phys. Rev. Lett. 77, 2913 (1996). In our experiment, atoms in a 87Rb condensate ...are exposed to laser light which is tuned close to the transition frequency to an excited molecular state. By controlling the power and detuning of the laser beam we can change the atomic scattering length over a wide range. In view of laser-driven atomic losses, we use Bragg spectroscopy as a fast method to measure the scattering length of the atoms.
Nanostructured Fibers via Electrospinning Bognitzki, M.; Czado, W.; Frese, T. ...
Advanced materials (Weinheim),
January, 2001, Letnik:
13, Številka:
1
Journal Article
Recenzirano
Structured polymer fibers with diameters down to tens of nanometers are of interest for applications in filters, in composite reinforcement, or as templates for the preparation of functional ...nanotubes. The Figure shows fibers of poly‐L‐lactide produced by electrospinning from a dichloromethane solution exhibiting regular pores or pits in the 100 nm range.
Pertussis, a serious infectious disease of the respiratory tract caused by Bordetella pertussis is reemerging in vaccinated populations. Efforts to curtail this disease are hampered by limited ...insight into the basis of protective immunity. Opsonophagocytosis was recently found to play a central role in cellular bactericidal activity against B. pertussis. In the present study, we studied the specificity of opsonic antibodies. Anti–pertactin antibodies, but not anti–pertussis toxin, anti-fimbriae, or anti–filamentous hemagglutinin antibodies, were found to be crucial for B. pertussis phagocytosis. These data are consistent with field studies showing that levels of antibodies to pertactin correlate with protection
A series of 1,3-diphenyl-6-alkyl/arylfulvenes was prepared, and the electrochemical properties were investigated. The addition of phenyl groups about the fulvene raised the reduction potential and ...helped to stabilize the electrochemically generated radical anion. The addition of various functional groups onto the phenyl ring at the 6-position of 1,3,6-triphenylfulvene results in a linear free energy relationship between reduction potential and the Hammett substituent constant, σ. Further extending the conjugation at the 6-position of 1,3-diphenyl-6-arylfulvenes increases the reversibility of the redox reactions, but does not appear to further stabilize the generated radical anion. This in-depth investigation provides evidence that the compounds studied may have utility in light-harvesting applications.
Coating extremely thin degradable template polymer fibers with the desired wall materials forms the basis of the straightforward and highly versatile method described here for the production of ...polymer, metal, and hybrid nano‐ and mesotubes. Tubes with highly structured inner surfaces (see Figure) may be fabricated, which is of great interest for applications requiring large surface/volume ratios (see also cover).
•Tungsten tile with different castellation structures was exposed to KSTAR plasmas.•The contribution of ions and neutrals on deposition inside the gap was studied.•The shaped castellation shows ...smaller penetration depth of ions by a factor of 1/2.•Blister formation and cracking have occurred during plasma shots.
A bulk tungsten tile with conventional and shaped castellation structures was exposed to various plasmas in KSTAR during 2012 campaign, in order to verify the functions of the shaped castellation designed for ITER divertor. The thermal response of the tile during the campaign was measured by thermocouples. The tungsten tile was collected after the campaign and the castellation structures were examined. The deposition inside the gap was studied to identify the contributions of ions and charge exchange neutrals. The shaped castellation shows a penetration depth of ions smaller than that of conventional one by a factor of ∼2, thus less deposition inside the gap which is consistent with the prediction made by SPICE2 code. It seems that blister formation and cracking have occurred during plasma shots.
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