On the existence of infinitely many periodic solutions to some problems of n-body type

We prove the existence of infinitely many periodic solutions with prescribed period to a class of problems of n-body type.     

A two-phase decision support framework for the automatic screening of digital fundus images

In this paper we give a brief review on the present status of automated detection systems describe for the screening of diabetic retinopathy. We further detail an enhanced detection procedure that consists of two steps. First, a pre-screening algorithm is considered to classify the input digital fundus images based on the severity of abnormalities. If an image is found to be seriously abnormal, it will not be analysed further with robust lesion detector algorithms. As a further improvement, we introduce a novel feature extraction approach based on clinical observations. The second step of the proposed method detects regions of interest with possible lesions on the images that previously passed the pre-screening step. These regions will serve as input to the specific lesion detectors for detailed analysis. This procedure can increase the computational performance of a screening system. Experimental results show that both two steps of the proposed approach are capable to efficiently exclude a large amount of data from further processing, thus, to decrease the computational burden of the automatic screening system.     

The mass spectrum of glycine

Irreproducibilities in the measurements of isotopic abundance in ¹⁵N labelled glycine have been related to the complex nature of chemical processes occurring during the evaporation of glycine prior to ionization.     

Application of the integrated ion-current technique to the study of rare-earth chelates

Several substituted acetylacetones have been prepared and reacted with holmium to give tris chelates of the form HoL₃. One of these chelates has been converted to a tetrakis chelate of the form NaHoL₄. The mass spectra of these compounds have been studied and the integrated ion currents at significant m/e values have been related to the amounts of metal chelates evaporated into the ion source of the mass spectrometer. The shape of the integrated ion-current curve is shown to give information about the nature of the evaporation process. When the β-diketone (L) is asymmetrical as in the case of 1,1,1-trifluoro-5,5-dimethylhexan-2,4-dione, the existence of geometrical isomers of the chelate, HoL₃, is reflected in the shape of the integrated ion-current curve, which shows fine structure. The results of mass spectrometric studies are compared with those of the sublimation and gas chromatographic behaviour of the metal chelates.     

TLC of substituted pyridines. XII. Hydroxy derivatives

Investigations were made to determine the TLC properties of monosubstituted pyridines. The primary aim was to identify and quantitatively

2. R_f Values of Monohydroxypyridines and other Monosubstituted Pyridines (Monoamines and Monocarboxylic Acids) in Systems I and II

determine the monohydroxypyridines formed during in vitro chemical and enzymatic hydroxylation experiments.TLC studies were carried out not only on the monosubstituted pyridines, but also on 2,3-di-OH-pyridine and 3-OH-pyridine-N-oxide.The UV absorption spectra of pyridine and its substituted derivatives were recorded at a concentration of 10⁻³ M in ethanol, and were compared.The best TLC detection of these derivatives was elaborated too.     

Interactions of Al(III) with a neurofilament heptapeptide fragment: AcLysSerProValValGluGly

The solution state of the neurotoxic Al(III) in biological systems is discussed briefly, and the importance of the Al(III)-peptide and Al(III)-protein interactions in the various neurodegeneration processes is emphasised and evaluated. The possible involvement of Al(III) in the formation of Alzheimer's disease marker senile plaques and neurofilament tangles is discussed in light of the solution speciation of the Al(III)-AcLysSerProValValGluGly system and the structural features of the complexes formed.     

Spectroscopy on two coupled superconducting flux qubits

We have performed spectroscopy measurements on two coupled flux qubits. The qubits are coupled inductively, which results in a sigma(z)(1)sigma(z)(2) interaction. By applying microwave radiation, we observe resonances due to transitions from the ground state to the first two excited states. From the position of these resonances as a function of the applied magnetic field, we observe the coupling of the qubits. The coupling strength agrees with calculations of the mutual inductance.     

Measurements of excess enthalpies at high temperature and pressure using a new type of mixing unit

A flow mixing unit (calorimetric cell and auxiliary devices) has been designed for measuring the enthalpy of mixing or reaction of two fluids (gas+liquid or liquid+liquid). The indicator of the heat effect is a differential heat flux calorimeter, SETARAM C-80, allowing measurements at temperatures up to 300°C. The mixing cell is made of a stainless-steel capillary (o.d 1.6 mm, length 2.4m) which is coiled in a cylindrical form and tightly fitted in the thermopile well of the calorimeter. The fluids are delivered from the high pressure piston pumps and circulated through the system at controlled flow rates ranging from 100 to 1500 L-min^–1. The tests were carried out at pressures up to 20 MPa. Special care was taken to allow good thermostatting of fluids entering the mixing cell. Check measurements were made with one liquid-liquid system (C₂H₅OH+H₂O) and one gas-liquid system (CO₂+C₆H₅CH₃); our enthalpies of mixing agreed with the literature values in most cases to 2%. For the system ethanol+water the experiments have been also performed at temperature of 250°C and pressures of 15 and 20 MPa. The endothermal mixing effect was higher than expected indicating an increase in the excess heat capacity.