Strong erbium luminescence in the near-infrared telecommunication window

A new type of near-infrared emitting rare-earth complex has been synthesised, consisting of three bis(perfluoroalkylsulfonyl)imide ligands and one 1,10-phenanthroline molecule. The chelate rings formed by the rare-earth ion and the bidentate ligands do not contain any carbon atoms and can hence be considered as 'inorganic' chelate rings. The absence of C-H stretching vibration modes in the first coordination sphere of the rare-earth ion and the presence of a light-harvesting moiety (1,10-phenanthroline) bound to the rare-earth ion result in a complex that can be efficiently excited and exhibits intense near-infrared luminescence. (C) 2004 Elsevier B.V. All rights reserved.

A study of magnetic bright points in the Na I D1 line.

High-cadence, multiwavelength, optical observations of solar magnetic bright points (MBPs), captured at the disk center using the ROSA and IBIS imaging systems on the Dunn Solar Telescope, are presented. MBPs manifesting in the Na I D-1 core are found to preferentially exist in regions containing strong downflows, in addition to cospatial underlying photospheric magnetic field concentrations. Downdrafts within Na I D-1 bright points exhibit speeds of up to 7 km s(-1), with preferred structural symmetry in intensity, magnetic field, and velocity profiles about the bright point center. Excess intensities associated with G-band and Ca II K observations of MBPs reveal a power-law trend when plotted as a function of the magnetic flux density. However, Na I D-1 observations of the same magnetic features indicate an intensity plateau at weak magnetic field strengths below approximate to 150 G, suggesting the presence of a two-component heating process: one which is primarily acoustic and the other predominantly magnetic. We suggest that this finding is related to the physical expansion of magnetic flux tubes, with weak field strengths (approximate to 50 G) expanding by similar to 76%, compared to a similar to 44% expansion when higher field strengths (approximate to 150 G) are present. These observations provide the first experimental evidence of rapid downdrafts in Na I D-1 MBPs and reveal the nature of a previously unresolved intensity plateau associated with these structures.

Maternal Glucose at 28 Weeks of Gestation Is Not Associated With Obesity in 2-Year-Old Offspring:The Belfast Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Family Study

OBJECTIVE:Diabetes during pregnancy is a strong risk factor for obesity in the offspring, but the age at which this association becomes apparent is unknown. The purpose of this study was to examine the relation of glycemia during pregnancy with anthropometry in offspring of nondiabetic pregnant women from the Belfast U.K. center of the multinational Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study.
RESEARCH DESIGN AND METHODS: Women from the HAPO Study were invited to participate in follow-up of their offspring aged 2 years. Measurements included height, weight, and thickness of triceps, subscapular, and suprailiac skinfolds. RESULTS: A total of 1,165 offspring (73% of eligible children; 598 boys and 567 girls) were seen from ages 22-30 completed months. The only association that reached statistical significance was between categories of maternal 1-h glucose and BMI Z score =85th percentile at 2 years (P = 0.017). Overall the correlations between maternal glucose during pregnancy and BMI Z score at age 2 years were weak (fasting glucose r = 0.05, P = 0.08; 1-h glucose r = 0.04, P = 0.22; 2-h glucose r = 0.03, P = 0.36; and area under the curve for glucose r = 0.04, P = 0.18).
CONCLUSIONS: This study found little association between maternal glucose during pregnancy and obesity in the offspring at this young age. These findings are not unexpected given that study results for young offspring whose mothers had diabetes during pregnancy were indistinguishable from those for normal offspring at this age. It will be interesting to see whether, as these children age, maternal glucose during pregnancy in the ranges included in the HAPO Study will be associated with obesity in their children. © 2010 by the American Diabetes Association.

Measuring conflict and agreement between two prioritized knowledge bases in possibilistic logic.

In this paper we investigate the relationship between two prioritized knowledge bases by measuring both the conflict and the agreement between them.First of all, a quantity of conflict and two quantities of agreement are defined. The former is shown to be a generalization of the well-known Dalal distance which is the hamming distance between two interpretations. The latter are, respectively, a quantity of strong agreement which measures the amount ofinformation on which two belief bases “totally” agree, and a quantity of weak agreement which measures the amount of information that is believed by onesource but is unknown to the other. All three quantity measures are based on the weighted prime implicant, which represents beliefs in a prioritized belief base. We then define a degree of conflict and two degrees of agreement based on our quantity of conflict and quantities of agreement. We also consider the impact of these measures on belief merging and information source ordering.

A low-energy core-collapse supernova without a hydrogen envelope

The final fate of massive stars depends on many factors. Theory suggests that some with initial masses greater than 25 to 30 solar masses end up as Wolf-Rayet stars, which are deficient in hydrogen in their outer layers because of mass loss through strong stellar winds. The most massive of these stars have cores which may form a black hole and theory predicts that the resulting explosion of some of them produces ejecta of low kinetic energy, a faint optical luminosity and a small mass fraction of radioactive nickel. An alternative origin for low-energy supernovae is the collapse of the oxygen-neon core of a star of 7-9 solar masses. No weak, hydrogen-deficient, core-collapse supernovae have hitherto been seen. Here we report that SN 2008ha is a faint hydrogen-poor supernova. We propose that other similar events have been observed but have been misclassified as peculiar thermonuclear supernovae (sometimes labelled SN 2002cx-like events). This discovery could link these faint supernovae to some long-duration gamma-ray bursts, because extremely faint, hydrogen-stripped core-collapse supernovae have been proposed to produce such long gamma-ray bursts, the afterglows of which do not show evidence of associated supernovae.

Simulation of a collisionless planar electrostatic shock in a proton-electron plasma with a strong initial thermal pressure change

The localized deposition of the energy of a laser pulse, as it ablates a solid target, introduces high thermal pressure gradients in the plasma. The thermal expansion of this laser-heated plasma into the ambient medium (ionized residual gas) triggers the formation of non-linear structures in the collisionless plasma. Here an electron-proton plasma is modelled with a particle-in-cell simulation to reproduce aspects of this plasma expansion. A jump is introduced in the thermal pressure of the plasma, across which the otherwise spatially uniform temperature and density change by a factor of 100. The electrons from the hot plasma expand into the cold one and the charge imbalance drags a beam of cold electrons into the hot plasma. This double layer reduces the electron temperature gradient. The presence of the low-pressure plasma modifies the proton dynamics compared with the plasma expansion into a vacuum. The jump in the thermal pressure develops into a primary shock. The fast protons, which move from the hot into the cold plasma in the form of a beam, give rise to the formation of phase space holes in the electron and proton distributions. The proton phase space holes develop into a secondary shock that thermalizes the beam.

Direct versus delayed pathways in strong-field non-sequential double ionization

We report full-dimensionality quantum and classical calculations of double ionization (DI) of laser-driven helium at 390 nm. Good agreement is observed. We identify the relative importance of the two main non-sequential DI pathways, the direct|with an almost simultaneous ejection of both electrons|and the delayed. We find that the delayed pathway prevails at small intensities independently of total electron energy but at high intensities the direct pathway predominates up to a certain upper-limit in total energy which increases with intensity. An explanation for this increase with intensity is provided.

Strong-field approximation for Coulomb explosion of H-2(+) and D-2(+) by short intense laser pulses

We present a simple quantum mechanical model to describe Coulomb explosion of H-2(+) and D-2(+) by short, intense infrared laser pulses. The model is based on the length gauge version of the molecular strong-field approximation and is valid when the process of dissociation prior to ionization is negligible. The results are compared with recent experimental data for the proton kinetic energy spectrum [Th. Ergler , Phys. Rev. Lett. 95, 093001 (2005); D. S. Murphy , J. Phys. B 40, S359 (2007)]. Using a Franck-Condon distribution over initial vibrational states, the theory reproduces the overall shape of the spectrum with only a small overestimation of slow protons. The agreement between theory and experiment can be made perfect by using a non-Frank-Condon initial distribution characteristic for H-2(+) (D-2(+)) targets produced by strong-field ionization of H-2 (D-2). For comparison, we also present results obtained by two different tunneling models for this process.

Eigenvalues of the time-delay matrix in overlapping resonances

We discuss the properties of the lifetime or the time-delay matrix Q(E) for multichannel scattering, which is related to the scattering matrix S(E) by Q = i?S(dS†/dE). For two overlapping resonances occurring at energies E with widths G(? = 1, 2), with an energy-independent background, only two eigenvalues of Q(E) are proved to be different from zero and to show typical avoided-crossing behaviour. These eigenvalues are expressible in terms of the four resonance parameters (E , G) and a parameter representing the strength of the interaction of the resonances. An example of the strong and weak interaction in an overlapping double resonance is presented for the positronium negative ion. When more than two resonances overlap (? = 1, ..., N), no simple representation of each eigenvalue has been found. However, the formula for the trace of the Q-matrix leads to the expression d(E) = -?arctan[(G/2)/(E - E)] + d(E) for the eigenphase sum d(E) and the background eigenphase sum d(E), in agreement with the known form of the state density. The formulae presented in this paper are useful in a parameter fitting of overlapping resonances. © 2006 IOP Publishing Ltd.

Qubit Residence Time Measurements with a Bose-Einstein Condensate

We show that an electrostatic qubit located near a Bose-Einstein condensate trapped in a symmetric double-well potential can be used to measure the duration the qubit has spent in one of its quantum states. The strong, medium, and weak measurement regimes are analyzed. The analogy between the residence and the traversal (tunnelling) times is highlighted.

Ownership structure, organisational flexibility and store performance in retail chains.

Drawing on agency and flexible capability perspectives, the authors develop a theoretical framework explaining the impact of ownership structure on organisational flexibility and store performance in retail chains. The researchers argue that franchised stores attract more entrepreneurial managers with more flexible capabilities and they have a stronger incentive to align their flexible capabilities with the demands of the business environment. A sample of 105 franchised and company-owned stores of an optical retail chain is used to test the hypotheses. Furthermore, the study found strong support for the hypotheses that 'Franchised stores have a higher structural flexibility than company-owned stores', but only weak support for operational and strategic flexible capabilities. Furthermore, in line with the study's theoretical framework, it has been found that in a highly turbulent business environment, franchised stores perform better than company-owned stores. The paper concludes with a discussion of the implications for theory development and management of ownership structures in retail chains.

PIM-1 kinase expression in adipocytic neoplasms: diagnostic and biological implications

The differential diagnosis of soft tissue tumours poses a considerable challenge for pathologists, especially adipocytic tumours, as these may show considerable overlap in clinical presentation and morphological features with many other mesenchymal neoplasms. Hence, a specific and reliable marker that identifies adipocytic differentiation is much sought. We investigated the immunohistochemical expression of PIM-1 kinase in 35 samples of soft tissue tumours using tissue microarray technology and 49 full sections of adipocytic (n = 26) and non-adipocytic tumours (n = 23). Benign and malignant adipocytic tumours showed strong expression of PIM-1 while the non-adipocytic tumours were either negative or showed only weak staining for the protein. In myxoid liposarcomas, PIM-1 showed a distinct, unique vacuolar staining pattern, clearly outlining fine cytoplasmic lipid vacuoles. By contrast, non-adipocytic myxoid tumours (myxoma, chordoma and myxoid chondrosarcoma) did not show this vacuolar pattern of PIM-1 staining, although vacuolated cells were present on H&E. This differential expression was confirmed at a gene expression level in selected cases. Our results indicate that the expression of PIM-1 in adipose tissue may be a useful marker of adipocytic differentiation, in particular if the staining is both of high intensity and present in a unique, vacuolar pattern.

Redistribution of vibrational population in a molecular ion with nonresonant strong-field laser pulses

We present an experimental demonstration of nonresonant manipulation of vibrational states in a molecule by an intense ultrashort laser pulse. A vibrational wave packet is generated in D-2(+) through tunnel ionization of D-2 by a few-cycle pump pulse. A similar control pulse is applied as the wave packet begins to dephase so that the dynamic Stark effect distorts the electronic environment of the nuclei, transferring vibrational population. The time evolution of the modified wave packet is probed via the D-2(+) photodissociation yield that results from the application of an intense probe pulse. Comparing the measured yield with a quasiclassical trajectory model allows us to determine the redistribution of vibrational population caused by the control pulse. ©