Profile‐based push models in manpower planning

A methodology is presented to deal with heterogeneity due to observable variables in modeling personnel systems. For a manpower system, a model based on personnel profiles is introduced. The proposed algorithm concerns an analysis of the evolution of personnel profiles under time‐discrete Markov assumptions. In this way, based on an historical personnel database, the estimation of transition probabilities of profiles as well as the computation of forecasts on the evolution of the manpower system can be found. Based on the presented procedure, a policy supporting software package has been developed for the Belgian Federal Government (research project financed by Federaal Wetenschapsbeleid). Copyright © 2007 John Wiley & Sons, Ltd.     

Recognition of essential purines by the U1A protein

Background  

The RNA recognition motif (RRM) is one of the largest families of RNA binding domains. The RRM is modulated so that individual proteins containing RRMs can specifically recognize RNA targets with diverse sequences and structures. Understanding the principles governing this specificity will be important for the rational modification and design of RRM-RNA complexes.     

Associations between Neurocardiovascular Signal Entropy and Physical Frailty

In this cross-sectional study, the relationship between noninvasively measured neurocardiovascular signal entropy and physical frailty was explored in a sample of community-dwelling older adults from The Irish Longitudinal Study on Ageing (TILDA). The hypothesis under investigation was that dysfunction in the neurovascular and cardiovascular systems, as quantified by short-length signal complexity during a lying-to-stand test (active stand), could provide a marker for frailty. Frailty status (i.e., “non-frail”, “pre-frail”, and “frail”) was based on Fried’s criteria (i.e., exhaustion, unexplained weight loss, weakness, slowness, and low physical activity). Approximate entropy (ApEn) and sample entropy (SampEn) were calculated during resting (lying down), active standing, and recovery phases. There was continuously measured blood pressure/heart rate data from 2645 individuals (53.0% female) and frontal lobe tissue oxygenation data from 2225 participants (52.3% female); both samples had a mean (SD) age of 64.3 (7.7) years. Results revealed statistically significant associations between neurocardiovascular signal entropy and frailty status. Entropy differences between non-frail and pre-frail/frail were greater during resting state compared with standing and recovery phases. Compared with ApEn, SampEn seemed to have better discriminating power between non-frail and pre-frail/frail individuals. The quantification of entropy in short length neurocardiovascular signals could provide a clinically useful marker of the multiple physiological dysregulations that underlie physical frailty.     

Insight in DNA Repair of UV‐induced Pyrimidine Dimers by Chromatographic Methods

UV‐induced formation of pyrimidine dimers in DNA is a major deleterious event in both eukaryotic and prokaryotic cells. Accumulation of cyclobutane pyrimidine dimers and pyrimidine (6‐4) pyrimidone photoproducts can lead to cell death or be at the origin of mutations. In skin, UV induction of DNA damage is a major initiating event in tumorigenesis. To counteract these deleterious effects, all cell types possess DNA repair machinery, such as nucleotide excision repair and, in some cell types, direct reversion. Different analytical approaches were used to assess the efficiency of repair and decipher the enzymatic mechanisms. We presently review the information provided by chromatographic methods, which are complementary to biochemical assays, such as immunological detection and electrophoresis‐based techniques. Chromatographic assays are interesting in their ability to provide quantitative data on a wide range of damage and are also valuable tools for the identification of repair intermediates.     

P NMR kinetic study of the tandem cleavage of phosphonate esters by bromotrimethylsilane

¹H and ³¹P NMR methods have been used to access rate constants and activation parameters for each of the consecutive second-order silylation reactions involved in the overall transformation (1a→3a→4a), while computational optimisation of the rate constants obtained from the initial, linear phase of each reaction has permitted an excellent fit with the experimental data for the entire course of the reaction.     

Ultrathin Carbon Film Electrodes from Vacuum‐Carbonised Cellulose Nanofibril Composite

A novel way to produce ultrathin transparent carbon layers on tin‐doped indium oxide (ITO) substrates is developed. The ITO surface is coated with cellulose nanofibrils (from sisal) via layer‐by‐layer electrostatic binding with poly(diallyldimethylammonium chloride) or PDDAC acting as the binder. The cellulose nanofibril‐PDDAC composite film is then vacuum‐carbonised at 500 °C. The resulting carbon films are characterised by atomic force microscopy (AFM), small angle X‐ray scattering (SAXS), wide‐angle X‐ray scattering (WAXS), and Raman methods. Smooth carbon films with good adhesion to the ITO substrate are formed. The electrochemical characterisation of the carbon films is based on the oxidation of hydroquinone and the reduction of benzoquinone in aqueous phosphate buffer media. A modest effect of the cellulose nanofibril‐PDDAC film on the rate of electron transfer is observed. The effect of the film on the rate of electron transfer after carbonisation is more dramatic. For a 40‐layer cellulose nanofibril‐PDDAC film after carbonisation a two‐order of magnitude change in the rate of electron transfer occurs presumably due to a better interaction of the hydroquinone/benzoquinone system with the electrode surface.     

Presenegenin Glycosides from Securidaca welwitschii

The five new presenegenin glycosides 1 – 5 were isolated from Securidaca welwitschii, together with one known sucrose diester. Compounds 1 – 4 were obtained as pairs of inseparable (E)/(Z)‐isomers of a 3,4‐dimethoxycinnamoyl derivative, i.e., 1 / 2 and 3 / 4 . Their structures were elucidated mainly by 2D‐NMR techniques and mass spectrometry as 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 1 ) and its (Z)‐isomer 2 , 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐{O‐β‐D ‐galactopyranosyl‐(1→4)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐3‐O‐acetyl‐α‐L ‐rhamnopyranosyl‐(1→2)‐O‐[β‐D ‐glucopyranosyl‐(1→3)]‐4‐O‐[(E)‐3,4‐dimethoxycinnamoyl]‐β‐D ‐fucopyranosyl} ester ( 3 ) and its (Z)‐isomer 4 , and 3‐O‐(β‐D ‐glucopyranosyl)presenegenin 28‐[O‐β‐D ‐galactopyranosyl‐(1→3)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐β‐D ‐fucopyranosyl] ester ( 5 ) (presenegenin=(2β,3β,4α)‐2,3,27‐trihydroxyolean‐12‐ene‐23,28‐dioic acid).