A case of silent invasion : citizen science confirms the presence of Harmonia axyridis (Coleoptera, Coccinellidae) in Central America

Harmonia axyridis (Coleoptera, Coccinellidae) is a globally invasive ladybird. It has been intentionally introduced in many countries as a biological control agent, whereas it has been unintentionally released in many others. Climatic factors are important in limiting the spread of H. axyridis. For example, very few records are known from tropical or desert regions. Currently, no published reports are known from Central America. Here, we report H. axyridis from Costa Rica, Guatemala, Honduras, Panama, and Puerto Rico. Specimens were either observed by the authors, discovered in dried insect collections, or retrieved from searching through online photographs available from the citizen science project iNaturalist and the photo-sharing website Flickr. These new records and the wide distribution of H. axyridis in Latin America suggest several invasion events, which have gone unnoticed until now. We stress the need for further, large-scale monitoring and show the advantage of citizen science to assess the presence of invasive alien species

Sonoluminescence: Nature's Smallest BlackBody

The Spectrum of the light emitted by a sonoluminescing bubble is extremely well fit by the spectrum of a blackbody. Furthermore the radius of emission can be smaller than the wavelength of the light. Consequences, for theories of sonoluminescence are discussed.Comment: 8 pages, 3 Figure

Hyperon forward spin polarizability gamma0 in baryon chiral perturbation theory

We present the calculation of the hyperon forward spin polarizability gamma0 using manifestly Lorentz covariant baryon chiral perturbation theory including the intermediate contribution of the spin 3/2 states. As at the considered order the extraction of gamma0 is a pure prediction of chiral perturbation theory, the obtained values are a good test for this theory. After including explicitly the decuplet states, our SU(2) results have a very good agreement with the experimental data and we extend our framework to SU(3) to give predictions to the hyperons' gamma0 values. Prominent are the Sigma^- and Xi^- baryons as their photon transition to the decuplet is forbidden in SU(3) symmetry and therefore they are not sensitive to the explicit inclusion of the decuplet in the theory

Soil hydraulic interpretation of nuclear magnetic resonance measurements based on circular and triangular capillary models

Geophysical nuclear magnetic resonance (NMR) applications are used to estimate pore size distributions (PSDs) of rocks and sediments. This is commonly realized by empirical calibration using information about the surface-to-volume ratio of the material. Recent research has developed joint inversion concepts for NMR relaxation data that provides the PSD with a minimum of information. The application requires the NMR signal of a sample at saturation and at least one at partial saturation and at known suction. The new inversion concept physically simulates the desaturation process as part of the forward operator. The cross-section of the model capillaries in the underlying bundle can be either circular or triangular. Our study investigates the performance of the NMR joint inversion to predict water retention function (WRF) and capillary-based hydraulic conductivity (Kcap) as functions of saturation for different sands. The angularity of the pores has no significant impact on the estimated WRF but affects the Kcap estimation significantly. Our study shows that the WRF is predicted reliably for sand samples under fast diffusion conditions. The Kcap estimations are also plausible but tend to systematic overestimation, for which we identified the tortuosity being the main reason. Because NMR relaxation data generally do not provide tortuosity information, a plausible tortuosity model remains an issue of classical calibration. Further development of the approach will thus consider tortuosity measurements (e.g., by electrical resistivity measurements and/or gradient NMR) and will consider the relaxation mechanisms outside fast diffusion conditions to enhance its applicability for coarse soils

Utilizing pre-polarization to enhance SNMR signals -- effect of imperfect switch-off

Surface nuclear magnetic resonance (SNMR) is a well-established technique for the hydrogeological characterization of the subsurface up to depths of about 150m. Recently, SNMR has been adapted to investigate also the shallow unsaturated zone with small surface loop setups. Due to the decreased volume, a pre-polarization (PP) field prior to the classical spin excitation is applied to enhance the measured response signal. Depending on the strength and orientation of the applied PP-field, the enhancement can often reach several orders of magnitude in the vicinity of the PP-loop. The theoretically achievable enhancement depends on the assumption of an adiabatic, i.e. perfect, switch-off of the corresponding PP-field. To study the effect of imperfect switch-off, we incorporate full spin dynamics simulations into the SNMR forward modeling. The affected subsurface volume strongly depends on the chosen PP switch-off ramp and the geometry of the loop setup. Due to the imperfect switch-off, the resulting SNMR sounding curves can have significantly decreased signal amplitudes. For comparison, the signal amplitudes of either a 1ms exponential or linear switch-off ramp are reduced by 17% and 65%, respectively. Disregarding this effect would therefore yield an underestimation of the corresponding subsurface water content of similar magnitude.Comment: preprint submitted to Geophysical Journal Internationa