Organic matter flow in the food web at a temperate heath under multifactorial climate change

The rising atmospheric CO(2) concentration, increasing temperature and changed patterns of precipitation currently expose terrestrial ecosystems to altered environmental conditions. This may affect belowground nutrient cycling through its intimate relationship with the belowground decomposers. Three climate change factors (elevated CO(2), increased temperature and drought) were investigated in a full factorial field experiment at a temperate heathland location. The combined effect of biotic and abiotic factors on nitrogen and carbon flows was traced in plant root → litter → microbe → detritivore/omnivore → predator food-web for one year after amendment with (15)N(13)C(2)-glycine. Isotope ratio mass spectrometry (IRMS) measurement of (15)N/(14)N and (13)C/(12)C in soil extracts and functional ecosystem compartments revealed that the recovery of (15)N sometimes decreased through the chain of consumption, with the largest amount of bioactive (15)N label pool accumulated in the microbial biomass. The elevated CO(2) concentration at the site for 2 years increased the biomass, the (15)N enrichment and the (15)N recovery in detritivores. This suggests that detritivore consumption was controlled by both the availability of the microbial biomass, a likely major food source, and the climatic factors. Furthermore, the natural abundance δ(13)C of enchytraeids was significantly altered in CO(2)-fumigated plots, showing that even small changes in δ(13)C-CO(2) can be used to detect transfer of carbon from primary producers to detritivores. We conclude that, in the short term, the climate change treatments affected soil organism activity, possibly with labile carbohydrate production controlling the microbial and detritivore biomass, with potential consequences for the decomposition of detritus and nutrient cycling. Hence, there appears to be a strong coupling of responses in carbon and nitrogen cycling at this temperate heath.     

Monitoring cellular responses upon fatty acid exposure by Fourier transform infrared spectroscopy and Raman spectroscopy

We investigated the applicability of FTIR-spectroscopy as a high throughput screening method for detection of biochemical changes in intact liver cells in bulk upon fatty acid exposure. HepG2 cells adapted to serum free (HepG2-SF) growth were exposed to four different fatty acids, three octadecenoic acids, differing in cis/trans-configuration or double bond position (oleic acid, elaidic acid and vaccenic acid) as well as palmitic acid in three days. High throughput FTIR spectroscopic measurements on dried films of intact cells showed spectra with high signal-to-noise ratio and great reproducibility. When applying principal component analysis (PCA) a clear discrimination between fatty acid exposures was observed. Higher levels of triacylglycerides were accumulated in cells exposed to elaidic acid than when exposed to the other fatty acids; the least accumulation appeared to be in cells exposed to palmitic acid. An increased absorption at ~966 cm(-1) corresponding to trans-double bond was detected upon elaidic acid exposure but not upon vaccenic acid exposure. Instead, upon vaccenic acid exposure two new absorption bands were observed at 981 and 946 cm(-1) due to the presence of double bond conjugation. Raman spectroscopy on single cells, with and without treatment by vaccenic acid, confirmed the presence of conjugation. By fatty acid composition analysis, the conjugation was further specified to be conjugated linoleic acid (CLA) isomers. Thus, instead of being preserved as a monounsaturated fatty acid, vaccenic acid was converted into CLA in HepG2 cells. The results demonstrate the applicability of high-throughput FTIR spectroscopy as an explorative method in in vitro systems from which biologically relevant hypotheses can be generated and further investigated.     

In pursuit of new physics with B^{0}_{s}\to K^{+}K^{-}

The sensitivity of the zero position of the forward–backward asymmetry $\mathcal{A}_{\mathit{FB}}$ for the exclusive $B\rightarrow K_{1}(1270)\mu^{+}\mu^{-}$ decay is examined by using most general non-standard four-fermion interactions. Our analysis shows that the zero position of the forward–backward asymmetry is very sensitive to the sign and size of the Wilson coefficients corresponding to the new vector type interactions, which are the counter partners of the usual Standard Model operators but have opposite chirality. In addition to these, the other significant effect comes from the interference of scalar–pseudoscalar and tensor type operators. These results will not only enhance our theoretical understanding of the axial vector mesons but will also serve as a good tool to look for physics beyond the SM.     

Extraterrestrial Mössbauer spectroscopy: more than 3 years of Mars exploration and developments for future missions

After almost 4 years of operating on the surface of Mars, Mössbauer spectroscopy has become a mature technique for robotic planetary exploration. The combination of quantitative information about the distribution of Fe among its oxidation and coordination states, identification of Fe-bearing phases, and relative distribution of Fe among those phases provides valuable contributions to the search for past water activity, the assessment of past environmental conditions, and the suitability for life of the two NASA Mars Exploration Rover landing sites. Experience from the Mars Exploration Rover Mission highlights needs for improvement of the instruments for future missions such as the Russian Phobos-Grunt and the European ExoMars rover.     

Observation of all-optical bump-on-tail instability

We demonstrate an all-optical bump-on-tail instability by considering the nonlinear interaction of two partially coherent spatial beams. For weak wave coupling, we observe momentum transfer with no variation in intensity. For strong wave coupling, modulations appear in intensity and evidence appears for wave (Langmuir) collapse at large scales. Borrowing plasma language, these limits represent regimes of weak and strong spatial optical turbulence. In both limits, the internal spectral energy redistribution is observed by recording and reconstructing a hologram of the evolving dynamics. The results are universal and can appear in any wave-kinetic system with short-wave-long-wave coupling.     

Uptake of silicone oil in the polystyrene matrix of the two phase system polystyrene/silicone oil as detected by NMR

The decrease of the droplet radii of silicone oil dispersed in a polystyrene matrix at a temperature of 140°C with increasing time was measured by NMR dynamic imaging. From this time dependence the diffusion coefficient of the silicone oil into the matrix was calculated to be 7 · 10⁻¹⁸ m² · s⁻¹. The uptake of the silicone oil in the polystyrene matrix was confirmed by broad line NMR measurements.