The Expressiveness of Locally Stratified Programs

This paper completes an investigation of the logical expressibility of finite, locally stratified, general logic programs. We show that every hyperarithmetic set can be computed by a suitably chosen locally stratified logic program (as a set of values of a predicate over its perfect model). This is an optimal result, since the perfect model of a locally stratified program is itself an implicitly definable hyperarithmetic set (under a recursive coding of the Herbrand base); hence to obtain all hyperarithmetic sets requires something new, in this case selecting one predicate from the model. We find that the expressive power of programs does not increase when one considers the programs which have a unique stable model or a total well-founded model. This shows that all these classes of structures (perfect models of locally stratified logic programs, well-founded models which turn out to be total, and stable models of programs possessing a unique stable model) are all closely connected with Kleene\u27s hyperarithmetical hierarchy. Thus, for general logic programming, negation with respect to two-valued logic is related to the hyperarithmetic hierarchy in the same way as Horn logic is to the class of recursively enumerable sets

Safety, quality, and processing of fruits and vegetables

Nowadays, one of the main objectives of the fruit and vegetable industry is to develop innovative novel products with high quality, safety, and optimal nutritional characteristics in order to respond with efficiency to the increasing consumer expectations. Various emerging, unconventional technologies (e.g., pulsed electric field, pulsed light, ultrasound, high pressure, and microwave drying) enable the processing of fruits and vegetables, increasing their stability while preserving their thermolabile nutrients, flavour, texture, and overall quality. Some of these technologies can also be used for waste and by-product valorisation. The application of fast noninvasive methods for process control is of great importance for the fruit and vegetable industry. The following Special Issue \u201cSafety, Quality, and Processing of Fruits and Vegetables\u201d consists of 11 papers, which provide a high-value contribution to the existing knowledge on safety aspects, quality evaluation, and emerging processing technologies for fruits and vegetables

One pot ‘click’ reactions: tandem enantioselective biocatalytic epoxide ring opening and [3+2] azide alkyne cycloaddition

Halohydrin dehalogenase (HheC) can perform enantioselective azidolysis of aromatic epoxides to 1,2-azido alcohols which are subsequently ligated to alkynes producing chiral hydroxy triazoles in a one-pot procedure with excellent enantiomeric excess.

Structure of the low lying levels of the 33S nucleus investigated by the 32S(d,p) 33S reaction

An investigation of the 32S(d, p)33S reaction was made at a deuteron bombarding energy of 12.3 MeV. The energy spectra were measured by magnetic analysis and the obtained angulardistributions were compared with the predictions of DWBA, using the deuteron optical model parameters obtained from an analysis of the elastic scattering of deuterons on 32S nuclei. The absolute values of spectroscopic factors, extracted on this basis, indicate a significant contribution of higher configurations in the ground state wave function of the 32S nucleus. There are no arguments which permit the identification of the observed states of the 33S nucleus as rotational states[...

Modelling, Analysis and Numerical Simulation of a Spring-Rods System with Unilateral Constraints

In this paper we consider a mathematical model which describes the equilibrium of two elastic rods attached to a nonlinear spring. We derive the variational formulation of the model which is in the form of an elliptic quasivariational inequality for the displacement field. We prove the unique weak solvability of the problem, then we state and prove some convergence results, for which we provide the corresponding mechanical interpretation. Next, we turn to the numerical approximation of the problem based on a finite element scheme. We use a relaxation method to solve the discrete problems that we implement on the computer. Using this method, we provide numerical simulations which validate our convergence results.Comment: 24 pages, 8 figure

Magnetization dynamics down to zero field in dilute (Cd,Mn)Te quantum wells

The evolution of the magnetization in (Cd,Mn)Te quantum wells after a short pulse of magnetic field was determined from the giant Zeeman shift of spectroscopic lines. The dynamics in absence of magnetic field was found to be up to three orders of magnitude faster than that at 1 T. Hyperfine interaction and strain are mainly responsible for the fast decay. The influence of a hole gas is clearly visible: at zero field anisotropic holes stabilize the system of Mn ions, while in a magnetic field of 1 T they are known to speed up the decay by opening an additional relaxation channel

Molecular photoswitches in aqueous environments

Molecular photoswitches enable dynamic control of processes with high spatiotemporal precision, using light as external stimulus, and hence are ideal tools for different research areas spanning from chemical biology to smart materials. Photoswitches are typically organic molecules that feature extended aromatic systems to make them responsive to (visible) light. However, this renders them inherently lipophilic, while water-solubility is of crucial importance to apply photoswitchable organic molecules in biological systems, like in the rapidly emerging field of photopharmacology. Several strategies for solubilizing organic molecules in water are known, but there are not yet clear rules for applying them to photoswitchable molecules. Importantly, rendering photoswitches water-soluble has a serious impact on both their photophysical and biological properties, which must be taken into consideration when designing new systems. Altogether, these aspects pose considerable challenges for successfully applying molecular photoswitches in aqueous systems, and in particular in biologically relevant media. In this review, we focus on fully water-soluble photoswitches, such as those used in biological environments, in both in vitro and in vivo studies. We discuss the design principles and prospects for water-soluble photoswitches to inspire and enable their future applications

Natural radioactivity of groundwater from the Przerzeczyn-Zdrój Spa

The present authors performed investigations of natural radioactivity in groundwater from the Przerzeczyn- -Zdrój Spa. Some of the waters are regarded as medical and are used for balneological purposes. Samples from seven groundwater intakes were collected 5 times over a period of 8 years (1999–2007). In order to obtain necessary data, two different nuclear spectrometry techniques were applied: α spectrometry and liquid scintillation spectrometry. The activity concentrations of 222Rn varied in the range from 15±2 Bq/l to 154±22 Bq/l. The results of activity concentrations of 226,228Ra varied from below 10 mBq/l to 30±1.5 mBq/l and from below 30 mBq/l to 60±4 mBq/l, respectively. Activity concentration lower than minimum detectable activity (MDA) was obtained for 3 samples for 226Ra and 4 for 228Ra determinations out of 7 investigated samples. The uranium content in the studied samples was determined once and the value ranged from 4.5±0.6 mBq/l to 13.6±1.2 mBq/l for 238U and from 17.1±0.9 mBq/l to 52.2±2.8 mBq/l for 234U. All obtained values for uranium isotopes showed activity concentrations above MDA. The activity ratios 234U/238U, 222Rn/226Ra and 226Ra/238U and the correlations between different isotopes concentrations were evaluated