Dynamics of Bose-Einstein condensates with atomic pumping and dissipative processes

In the dynamics of condensed systems described by a nonconservative non-linear Schrödinger equation, we investigate numerically the role of atomic feeding and inelastic collisions where dipolar relaxation is the dominant process. By analyzing the range of possible values of the nonconservative parameters to have stable (or unstable) solutions, we verify that spatio-temporal chaos patterns, known for attractive two-body systems due to collapsing effects, can also occur in the repulsive case when the term corresponding to the linear atomic feeding dominates the nonconservative contributions.     

Influence of photoperiod and running wheel access on the entrainment of split circadian rhythms in hamsters

Background  

In the laboratory, behavioral and physiological states of nocturnal rodents alternate, with a period near 24 h, between those appropriate for the night (e.g., elevated wheel-running activity and high melatonin secretion) and for the day (e.g., rest and low melatonin secretion). Under appropriate 24 h light:dark:light:dark conditions, however, rodents may be readily induced to express bimodal rest/activity cycles that reflect a global temporal reorganization of the central neural pacemaker in the hypothalamus. We examine here how the relative length of the light and dark phases of the environmental cycle influences this rhythm splitting and the necessity of a running wheel for expression of this entrainment condition.     

Electronic spectra of potassium bromide containing thallium II. Emission spectrum excited at 2537 Å

The emission spectrum of KBr: Tl⁺ excited at 2537 Å has been measured in the temperature range 15–296°K. At low temperatures the spectrum consists of a prominent band at 4.01 eV, a much smaller band at 3.40 eV and a very small band at 3.15 eV. The last does not appear to change much with temperature and so could not be measured accurately. The temperature-dependence of the two main bands is complex. Between 60 and 100°K the low-energy band increases sharply in intensity, while the high-energy band decreases correspondingly. Above 110°K the situation reverses and the low-energy band decreases in intensity while the high-energy band grows. Both bands closely approximate symmetric Gaussians. The temperature-dependence of the intensity of these two bands is well-explained qualitatively by the existence of two kinds of minima on the adiabatic potential energy surface for the A state. However, predictions of the temperature-dependence of the two emission bands based on calculated adiabatic potential energy surfaces are not in quantitative agreement with the experimental results. Possible reasons for this are our lack of knowledge of precise values for the parameters which enter into the theory, namely the spin-orbit coupling constant, the exchange integral, and the electron lattice coupling constant. The possible role of the ³A_1u state in emission is discussed briefly.     

Relations between a manifold and its focal set

Summary Throughout this paper, smooth meansC . All manifolds and embeddings will be smooth. By aclosed m-manifold we mean a compact connected manifold of dimensionm, without boundary.LetM be a closedm-manifold (m>0), andf: ME ⁿ an embedding in Euclideann-space. The focal points off are the centres of principal curvature (with respect to some normal direction) of the embedded manifoldf(M). These points form thefocal set C(f) off.The starting point for our investigation is the following problem. Is there any relation between the topological structure ofM and the relative positions ofC(f) andf(M) inE ⁿ ? In particular, canf be so chosen thatC(f) andf(M) are disjoint? We say that such an embedding isnonfocal.We find that there are manifolds for which no such embedding exists.     

Quantitative analysis using gas chromatography/combustion/isotope ratio mass spectrometry and standard addition of intrinsically labelled standards (SAIL)--application to isoflavones in foods

We have investigated a novel application of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) for the quantitative analysis of the isoflavones in food matrices. Previous methods have been hampered by the lack of analytical standards to introduce early enough in the extraction procedure to allow compensations for losses at all stages of the procedure. In this work we have produced standard materials that can be added at the initial extraction, by intrinsically labelling soya plants by growing them in an atmosphere enriched in the stable isotope of carbon in CO(2). On analysis these plants were shown to contain phytoestrogens at a high (up to 20%) level of enrichment. The dried plant material has been used to estimate the isoflavone concentrations of a set of spiked flours. For daidzein the methodology was shown to produce results comparable to those achieved by GC/MS techniques. The method was less successful for genistein, possibly due to the greater fragility of this compound under the conditions required for the analysis.     

Influence of oxidation state of sulfur on the dissociation of [Tz-(CH2)n-S(O)m-(CH2)n-Tz + Na+] adducts generated by electrospray ionization (Tz = tetrazole ring; n = 2, 3; m= 0, 1, 2)

Sodium adducts of six organosulfur‐α,ω‐ditetrazole compounds (Tz‐(CH₂)_n‐S(O)_m‐(CH₂)_n‐Tz; where Tz = tetrazole ring; n = 2, 3; m = 0, 1, 2) were generated via electrospray ionization (ESI) and their fragmentation pattern assessed via collision‐induced dissociation (CID). Two main dissociation channels were observed: (a) losses of N₂ and HN₃ from the tetrazole rings; (b) cleavage of the C–S bond. The sulfoxides pass predominantly through the second fragmentation pathway, but for the sulfides and sulfones the tetrazole ring fragmentation occurs. Theoretical calculations at the B3LYP/6‐31 + G(d,p) level indicate that for all the adducts (sulfide, sulfoxide, and sulfone) the dissociation pathway that leads to product ions arising from loss of N₂ was the most exothermic. Based on these results and assumptions, it was postulated that the dissociation of the sulfoxide adducts occurs under kinetic control (N₂‐loss pathway via a much more energetic transition state). For the sulfide and sulfone adducts, on the other hand, the dissociation process takes place via a thermodynamically controlled process. Copyright © 2011 John Wiley & Sons, Ltd.     

Novel method for ultraviolet protection and flame retardancy of cotton fabrics by low-temperature plasma

A novel approach, namely the nitrogen plasma technique, to confer flame-retardant and ultraviolet (UV)-protective properties on cotton fabric is described. Treated cotton fabrics showed very good UV-blocking property. According to the standard, the treated cotton fabric can be claimed to be a “UV-protective” product. The fire-retardant character of the treated fabrics was investigated by char yield, thermogravimetric analysis, and limiting oxygen index measurements. Also, the effect of aging on the mentioned properties was studied. The ultraviolet protection factor and flame-retardant properties of atmospheric pressure plasma-treated cotton were also measured and compared with nitrogen plasma treatment.     

Free radicals in γ-irradiated poly-α-methylstyrene

Electron spin resonance (ESR) spectra were observed at ?160°C and at room temperature for γ-irradiated poly-α-methylstyrene. The spectrum observed at room temperature has been attributed to the radical species while that at ?160°C results from the same radical and superposition of the spectrum due to the radical ?H₂-C(CH₃)(C₆H₅)-. The radicals which are stable at room temperature could be used to graft vinyl acetate.