bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of water on the work function of conducting poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)
Authors: Koch N. , Vollmer A. , Elschner A.
Published: January 2007

The influence of water exposure on the work function (ϕ) and surface composition of conducting poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDT:PSS) was investigated with ultraviolet and x-ray photoelectron spectroscopies. It was found that annealing PEDT:PSS in vacuum to 220°C yields a high ϕ of 5.65eV. Subsequent exposure to water vapor or air reduces ϕ to ∼5.15eV, and the film surface becomes enriched with PEDT. These observations were fully reversible for repeated annealing–water exposure cycles. The reduction in ϕ is attributed to (i) the inclusion of water leading to a larger dielectric constant and (ii) polymer swelling-induced rearrangements of surface dipoles.
Cavity resonances in finite plasmonic chains
Authors: Ghenuche P. , Cormack I. G. , Badenes G. , Loza-Alvarez P. , Quidant R.
Published: January 2007

The authors report on the observation of cavity resonances along finite gold nanoparticle chains which, unlike continuous gold nanowires, lead to a high field concentration at their extremity. The mode signature has been assessed by probing the local field bound to the metal with two-photon luminescence spectroscopy. Simulations based on the Green dyadic method corroborate a good agreement with the measurements and bring further insight to the physics involved.
Low-field inverse magnetocaloric effect in Ni50−xMn39+xSn11 Heusler alloys
Authors: Han Z. D. , Wang D. H. , Zhang C. L. , Xuan H. C. , Gu B. X. , Du Y. W.
Published: January 2007

The low-field magnetic entropy changes in Ni50−xMn39+xSn11 alloys (x=5, 6, and 7) were investigated. The martensitic transition shifts to lower temperature with the increase of Mn concentration. Under an applied magnetic field of 10kOe, the magnetic entropy changes are 6.8, 10.1, and 10.4J∕kgK, for x=5, 6, and 7, respectively. The large entropy change in Ni50−xMn39+xSn11 can be attributed to the sharp magnetization change associated with the martensitic transition from a ferromagnetic parent phase to a weak-magnetic martensitic phase. The large low-field magnetic entropy change and low cost suggest Ni50−xMn39+xSn11 alloy as the promising magnetic refrigerant.
Classical treatment of molecular collisions: striking improvement of the description of recoil energy distributions using Gaussian weighted trajectories
Authors: González-Martínez M. L. , Bonnet L. , Larrégaray P. , Rayez J.-C.
Published: January 2007

The Gaussian weighting (GW) procedure, recently used in the classical treatment of molecular collisions, is a practical way of taking into account quantization of product vibrational actions. The goal of this brief communication is to show that the GW procedure may drastically improve the predictions of the recoil energy distribution between final fragments, an observable frequently measured in molecular beam experiments.
Evolution of W optical center in Si-implanted epitaxial SiGe at low temperature annealing
Authors: Tan J. , Davies G. , Hayama S. , Nylandsted Larsen A.
Published: January 2007

The authors have investigated the effect of Ge concentration on the evolution of W optical center (W center) in Si-implanted epitaxial Si1−xGex at low temperature annealing. From the results of photoluminescence, the annealing behavior of W center can be separated into two regimes, i.e., W centers in Si1−xGex alloy with Ge <5% are stable, otherwise not stable. The annealing behavior of W center is similar to {311} defect in Si1−xGex. It is suggested that the dissipation of excess interstitials by outdiffusion at low temperature is one of the candidate mechanisms for the retardation of transient enhanced diffusion of boron in Si1−xGex.
Generation of continuous-wave broadband entangled beams using periodically poled lithium niobate waveguides
Authors: Yoshino Ken-ichiro , Aoki Takao , Furusawa Akira
Published: January 2007

Continuous-wave light beams with broadband quantum entanglement are created with two independent squeezed light beams generated by two periodically poled lithium niobate waveguides and a symmentric beam splitter. The quantum entanglement is confirmed with a sufficient criterion ΔA,B2=⟨[Δ(x̂A−x̂B)]2⟩+⟨[Δ(p̂A+p̂B)]2⟩<1 and the observed ΔA,B2 is 0.75 over the bandwidth of 30MHz. Although the bandwidth is limited by that of the detector so far, it would be broadened up to 10THz which would be only limited by the bandwidth of phase matching for the second-order nonlinear process.
Photovoltaic enhancement of organic solar cells by a bridged donor-acceptor block copolymer approach
Authors: Sun Sam-Shajing , Zhang Cheng , Ledbetter Abram , Choi Soobum , Seo Kang , Bonner Carl E. , Drees Martin , Sariciftci Niyazi Serdar
Published: January 2007

The authors show that a photovoltaic device composed of a -donor-bridge–acceptor-bridge- type block copolymer thin film exhibits a significant performance improvement over its corresponding donor/acceptor blend (Voc increased from 0.14to1.10V and Jsc increased from 0.017 to 0.058mA∕cm2) under identical conditions, where donor is an alkyl derivatized poly-p-phenylenevinylene (PPV) conjugated block, acceptor is a sulfone-alkyl derivatized PPV conjugated block, and bridge is a nonconjugated and flexible unit. The authors attribute such improvement to the block copolymer intrinsic nanophase separation and molecular self-assembly that results in the reduction of the exciton and carrier losses.
Characterizing the unfolded states of proteins using single-molecule FRET spectroscopy and molecular simulations
Authors: Merchant Kusai A. , Best Robert B. , Louis John M. , Gopich Irina V. , Eaton William A.
Published: January 2007

To obtain quantitative information on the size and dynamics of unfolded proteins we combined single-molecule lifetime and intensity FRET measurements with molecular simulations. We compared the unfolded states of the 64-residue, α/β protein L and the 66-residue, all-β cold-shock protein Csp
Tm
. The average radius of gyration (
R
g
) calculated from FRET data on freely diffusing molecules was identical for the two unfolded proteins at guanidinium chloride concentrations >3 M, and the FRET-derived
R
g
of protein L agreed well with the
R
g
previously measured by equilibrium small-angle x-ray scattering. As the denaturant concentration was lowered, the mean FRET efficiency of the unfolded subpopulation increased, signaling collapse of the polypeptide chain, with protein L being slightly more compact than Csp
Tm
. A decrease in
R
g
with decreasing denaturant was also observed in all-atom molecular dynamics calculations in explicit water/urea solvent, and Langevin simulations of a simplified representation of the polypeptide suggest that collapse can result from either increased interresidue attraction or decreased excluded volume. In contrast to both the FRET and simulation results, previous time-resolved small-angle x-ray scattering experiments showed no collapse for protein L. Analysis of the donor fluorescence decay of the unfolded subpopulation of both proteins gives information about the end-to-end chain distribution and suggests that chain dynamics is slow compared with the donor life-time of ≈2 ns, whereas the bin-size independence of the small excess width above the shot noise for the FRET efficiency distributions may result from incomplete conformational averaging on even the 1-ms time scale.
Secreted frizzled related protein 2 (Sfrp2) is the key Akt-mesenchymal stem cell-released paracrine factor mediating myocardial survival and repair
Authors: Mirotsou Maria , Zhang Zhongyan , Deb Arjun , Zhang Lunan , Gnecchi Massimiliano , Noiseux Nicolas , Mu Hui , Pachori Alok , Dzau Victor
Published: January 2007

Stem cell therapy has emerged as a promising tool for the treatment of a variety of diseases. Previously, we have shown that Akt-modified mesenchymal stem cells mediate tissue repair through paracrine mechanisms. Using a comprehensive functional genomic strategy, we show that secreted frizzled related protein 2 (Sfrp2) is the key stem cell paracrine factor that mediates myocardial survival and repair after ischemic injury. Sfrp2 is known to modulate Wnt signaling, and we demonstrate that cardiomyocytes treated with secreted frizzled related protein increase cellular β-catenin and up-regulate expression of antiapoptotic genes. These findings reveal the key role played by Sfrp2 in mediating the paracrine effects of Akt-mesenchymal stem cells on tissue repair and identify modulation of Wnt signaling as a therapeutic target for heart disease.
Synthesis of
Clostridium cellulovorans
minicellulosomes by intercellular complementation
Authors: Arai Takamitsu , Matsuoka Satoshi , Cho Hee-Yeon , Yukawa Hideaki , Inui Masayuki , Wong Sui-Lam , Doi Roy H.
Published: January 2007

The ability of two strains of bacteria to cooperate in the synthesis of an enzyme complex (a minicellulosome) was examined. Three strains of
Bacillus subtilis
were constructed to express
Clostridium cellulovorans
genes
engB
,
xynB
, and
minicbpA
. MiniCbpA, EngB, and XynB were synthesized and secreted into the medium by
B. subtilis
. When the strains with the
minicbpA
and
engB
genes or with
xynB
were cocultured, minicellulosomes were synthesized, consisting in one case of miniCbpA and EngB and in the second case of miniCbpA and XynB. Both minicellulosomes showed their respective enzymatic activities. We call this phenomenon “intercellular complementation.” Interesting implications concerning bacterial cooperation are suggested from these results.
Is sialic acid in milk food for the brain?
Authors: Karim M. , Wang Bing Wang Bing
Published: January 2007

The rapid brain growth of infants places exceptionally high demands on the supply of nutrients from the diet. Human milk is the best source of food for brain growth and cognition. One of nature's richest sources of sialic acid, a vital component of brain gangliosides and the building block of polysialic acid (PSA) on neural cell adhesion molecule (NCAM), is found in human breast milk. However, infant formulas contain very little amounts. Gangliosides and polysialylated NCAM in the brain have an important role in cell-to-cell interactions, neuronal outgrowth, modifying synaptic connectivity, and memory formation. An exogenous source of sialic acid may be critical under conditions of extremely rapid brain growth, particularly during the first months after birth. Here we review the major differences in sialic acid concentration between human milk and infant formulas, and how sialic acid-bearing nutrients are metabolized. The role of this essential micronutrient in the developing brain is examined, particularly with respect to PSA, which has a major effect on brain plasticity.
Blackleg in ruminants.
Authors: Useh N. M. , Nok A. J. , Esievo K. A. N.
Published: January 2007

Blackleg is a per acute or acute and fatal disease of cattle and sheep caused by
Clostridium chauvoei
Jakari, Vom and K76 strains in Nigeria, strains NCTC 8070 and 8361 in UK, strain 49 in India and other parts of Asia, strain NC08596 in Germany and other parts of Europe and America, strains ch.16 and ch.22 in Mozambique and Tanzania and strain Awasa in Ethiopia, respectively. The haematological and biochemical changes observed in ruminants with blackleg include haemoconcentration (increased packed cell volume, haemoglobin concentration, red blood cell counts, and total plasma protein concentration), increased erythrocyte sedimentation rate (ESR), decrease in total and differential leucocyte counts (leucopaenia, panleucopaenia i.e. lymphopaenia, neutropaenia, eosinopaenia and monocytopaenia), thrombocytopaenia, increased plasma neuraminidase activity, increased erythrocyte surface and plasma sialic acid concentration, increased levels of serum lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and increased creatine kinase (CK) activity. The leucopaenia and decrease in differential leucocyte counts, increase in plasma sialic acid concentration and decrease in erythrocyte surface sialic acid levels were attributed to the action of neuraminidase, whose activity is increased in the plasma in clinical blackleg. The neuraminidase produced by
C. chauvoei
is reported to possibly play a significant role in the inflammation and vascular permeability which are observed in blackleg. The pathological changes observed in cattle, sheep and deer with blackleg are essentially similar and are discussed. Some herbal remedies (
Tamarindus indicus
and
Combretum fragrans
) have been used by the transhumance (nomadic) Fulani pastoralists of rural Nigeria to successfully treat the disease. The economic losses of ruminants to the disease have not been quantified in most countries of the world, but in Nigeria, annual losses of cattle to it have been estimated at US$4.3 million. Vaccination has remained the best control strategy against the disease, which is endemic in Africa, USA, Central and Southern America, Asia and Europe.
Protein nutrition in crustaceans.
Authors: Mente E.
Published: January 2007

Successful commercial aquaculture of crustacean species is dependent on satisfying their nutritional requirements and on producing rapidly growing and healthy animals. This paper provides an overview of current knowledge on protein nutrition in crustaceans with emphasis on the species used in aquaculture and briefly examines important directions for future research. Research studies on the nutrition of crustaceans such as shrimp and lobster began at least 15 years after similar research on fish nutrition. Protein is the most critical ingredient in crustacean diets with regard to both the economic cost of diet production and growth response in culture. Crustaceans are reported to have higher protein requirements than finfish with levels from 60% of the diet for some postlarvae, to about 3050% of the diet for shrimps and lobsters. Salinity, age and the physiological state of crustaceans influence to different extents the utilization of dietary protein as energy source and growth. The nutritive value of dietary protein is governed by the extent to which its amino acid content satisfies the needs of the animal in question. Essential amino acid requirements for crustaceans still need to be quantified for various species. However, the ideal amino acid profile has yet to be defined for species of crustaceans. Future studies on theirphysiology, protein metabolism and immunological condition are required in a range of crustaceans to complete our understanding of their protein nutrition.
Stimulating private investment in agricultural research for greater impact on poverty reduction.
Authors: Marr A. , Chancellor T.
Published: January 2007

This article reviews the international experience with approaches to encouraging private investment in agricultural research and technology for a greater impact on poverty reduction. Some specific types of technologies and the roles for public and private sector involvement in generating new technology are identified, as well as the potential for public-private partnerships. Three most promising mechanisms for stimulating private investment in agricultural research are then revised in some detail: taxation schemes, co-funding arrangements, and output-based approaches. The article concludes that in order to help create a significant impact on poverty reduction, the innovative incentive system of tying rewards to adoption of technology development is the most likely to succeed.
Mössbauer Study of Hexagonal FeGe
Authors: Lennart Häggström  , Tore Ericsson  , Roger Wäppling  , Erik Karlsson
Published: January 2007

Mössbauer spectroscopic studies of the hexagonal antiferromagnet FeGe have been undertaken in the temperature range 10-430 K. The temperature variation of the magnetic hyperfine field for iron deviates from Brillouin function behaviour. From the values ofBhfclose to the ordering temperature the critical exponent β=0.328 and the Neél temperatureTN=398 K were obtained. The close similarity between isostructural binary compounds in the iron-germanium and the iron-tin systems as regards magnetic properties is stressed.
High Resolution Measurements of Atomic and Molecular Lifetimes Using the High Frequency Deflection Technique
Authors: Peter Erman
Published: January 2007

The basic principles of the High Frequency Deflection (HFD) technique for the determination of atomic and molecular lifetimes as well as the first experimental tests were presented a couple of years ago. In principle this technique is a further refinement of the conventional multichannel delayed coincidence technique with periodic electron excitation of free molecules. The differences are mainly that the HFD technique utilizes a continuous electron beam from a high-power gun operating in the kilovolt range and that the periodic excitation is accomplished by sweeping the beam at an optimal rate, i.e. with a period equal to 3-10 times the lifetime to be studied. With these two refinements the HFD technique enables lifetime measurements in all kinds of atoms, molecules, ions and ion-molecules with several orders of magnitude higher efficiency than other methods permit, thus opening possibilities for high resolution work in the absence of Doppler broadening. Thus a number of lifetimes have been determined at a spectral resolution of 0.1 Å FWHM or better, which is 20-50 times higher a resolution than what is normally achieved in lifetime measurements. The variable sweep frequency and the multichannel registration make possible measurements over a large lifetime range (up to about 104ns) which in turn offers unique possibilities for analysing multi-exponential decay curves. With a time scale of arbitrary precision given by the sweep frequency, lifetime measurements have so far been performed with a total error down to 0.5% in favourable cases.

The HFD technique is now currently in use at this laboratory and several hundreds of lifetimes have been studied and reported in a number of publications. In this paper we shall discuss more in detail the technique itself, its properties and possibilities compared to other methods for lifetime measurements. A review of some of the experimental results obtained so far, with particular emphasis on abundance determinations of atoms and molecules of fundamental astrophysical interest, is also included as well as a critical discussion of given error limits in lifetime measurements in general.
Studies of (p, d) Reactions in24Mg,32S and40Ca at 185 MeV
Authors: J Källne  , B Fagerström
Published: January 2007

Differential cross sections have been measured in the region 2.5° ⩽ θ ⩽ 40° for the reactions24Mg(p,d)23Mg,32S(p,d)31S and40Ca(p,d)39Ca atEp= 185 MeV. The deuterons were analysed with a magnetic spectrometer with an energy resolution of typically 260 keV (FWHM). The shape of the angular distributions showed a dependence on thenlj-values of the transferred neutron with the 1d3/2-transfers in24Mg(p,d)23Mg being exceptions. The excitation of high-spin states gave angular distributions of shapes untypical of direct pick-up reactions indicating contributions from two-step processes. Spectroscopic factors (C2S) were extracted by a DWBA analyses of the data. The results were compared with theC2S-values of other experiments and theoretical predictions and only partial agreement was observed. Instead there were some conspicuous differences e.g., the results on the ratioC2S(l+1/2)/C2S(l-1/2) was found to vary with the kind of projectile used in the experiment. This indicated shortcomings in the DWBA analyses which is shortly discussed. In the energy rangeEx≲ 10 MeV, six (1p)-1states were observed in23Mg and one such state was observed in31S. Spin-parity assignments are suggested for some vaguely known states in23Mg,31S and39Ca.
Hyperfine Interactions and ESCA Data
Authors: D A Shirley
Published: January 2007

A comparison is made of those data obtained from ESCA and from hyperfine interactions that bear on the same problems. A formal Hamiltonian can be written in which ESCA shifts and structure are discussed as E0, M1, E2,... terms. Under the E0 term core-level shifts are compared with isomer shifts and diamagnetic shifts. The M1 term refers to exchange splitting (core polarization). Multiplet splitting can identify local moments with fluctuation times down to 10-15 s. Rare earths and the 3d group are considered. The E2 term yields a crystal-field energy transforming as Y
2
0 and correlated with e
2
qQ in metals. Finally the valence-band density of states in noble metals can be related to a Y
4 term if nearest neighbors in metals are effectively negative; i.e., conduction electrons, rather than ion cores, are dominant.
Negative Moun Spin Rotation
Authors: T Yamazaki  , K Nagamine  , S Nagamiya  , O Hashimoto  , K Sugimoto  , K Nakai  , S Kobayashi
Published: January 2007

The possibility of using the muon spin rotation for solid-state studies is discussed. Some preliminary experimental results of negative muon spin rotation experiments related to g-factor measurements in diamagnetic metals and relaxation phenomena in transition metals are presented.
The Investigation of Radiation Damage and Lattice Location by Nuclear Hyperfine Interaction Techniques
Authors: H de Waard
Published: January 2007

Nuclear hyperfine interaction investigations of radiation damage are reviewed. Emphasis is laid on implantation experiments, where nuclear radiation emitted by the implanted probes conveys information about defect structure and its annealing. Various nuclear hfi techniques are briefly discussed and their merits and limitations for radiation damage studies are compared. It is pointed out how defect rearrangements that occur in various annealing stages can be recognized from their influence on hyperfine interactions. Recent experiments that provide more than qualitative information about radiation damage are discussed in some detail. Where possible, hfi and channeling results are compared. The importance of extending the implantation dose range to lower doses so as to avoid overlap effects of damage cascades is emphasized.
Solid State Information from Magnetic Hyperfine Interaction Studied In-Beam
Authors: E Recknagel
Published: January 2007

Perturbed angular distribution methods (PAD) following nuclear reactions have been employed to study hyperfine interactions in solids. Special properties of these In-Beam techniques are discussed. The large number of nuclear probes, the inherent time scale given by the lifetimes of the excited states, the independence of the alignment on macroscopic parameters and other features, allow investigations which are able to compete with other methods or are even exclusive. Measurements of magnetic hyperfine interactions such as hyperfine fields, critical exponents or Knight shifts are reviewed and discussed with regard to the specific properties.
Recent Developments in the Calculation of Hyperfine Anomalies and Electric Field Gradients in Ferromagnetic Metals and Alloys
Authors: G A Gehring
Published: January 2007

The detailed mechanisms which can give rise to changed hyperfine anomalies and electric field gradients in ferromagnetic metals and alloys are discussed. It is shown that both of these effects are caused by spin orbit coupling. Calculations of these effects are discussed for alloys and pure metals. A relation between the electric field gradient and the Anomalous Hall Effect is discussed.
Electric Quadrupole Interaction Studies Following Nuclear Reactions
Authors: H Haas
Published: January 2007

The time-differential perturbed angular distribution (DPAC) technique may be employed to study the nuclear quadrupole interaction in solids, including many systems not measurable by other methods. A "state of the art" report on recent experiments is given. The difficulties and limitations of this method are due to the timing conditions, the target lattices available, and, foremost, the radiation damage created by the recoil nucleus. Possibilities to overcome these problems and some extensions of the technique are discussed. A large amount of data already now exists, particularly for the s-p metals. At several instances, however, "key" experiments by other HFI techniques would be needed to accurately determine the nuclear quadrupole moments and electric field gradients involved.
Current Flow in Ion-Acoustic and Langmuir Turbulence Plasma Interaction
Authors: Tsytovich V N , Stenflo L , Wilhelmsson H
Published: January 2007

The process of Langmuir and ion-acoustic turbulence interaction due to turbulent bremsstrahlung collisions is considered. It is shown that the ion-sound turbulence excites the Langmuir turbulence even for isotropic particle distributions but for anisotropic ion-sound turbulent waves. The presence of both ion-sound and Langmuir turbulence may lead to the excitation of currents which cause strong magnetic fields.
On Parameter-free Closing Assumptions for the BBGKY-hierarchy
Authors: Dobbertin R
Published: January 2007

The variation of the distribution functions of a classical N-particle system has been studied. The results have been used to consider the problem of closing the BBGKY hierarchy, from a new standpoint.
Soliton Gas Bremsstrahlung
Authors: Lebedev A N , Tsytovich V N
Published: January 2007

Bremsstrahlung of sound and Langmuir waves from a soliton gas is considered. The rate of soliton merging is discussed.
Phase-broadening and Phase-focusing Effects in Nonlinear Partially Coherent Interaction
Authors: Weiland J , Wilhelmsson H , Kaufman A N , Tsytovich V N
Published: January 2007

The nonlinear interaction of three wave-packets has been studied numerically, in the case where one wave initially is much higher excited than the others. The evolutions of phase spreads in the wave packets and of the intensities have been considered in some detail. In particular, the phase spreads are found to grow after a characteristic time of interaction. This growth may then be followed by an oscillation between phase spread and phase focusing of the modes.
Effects of Linear Damping on Nonlinearly Coupled Waves
Authors: Sävenstedt T , Wilhelmsson H
Published: January 2007

An investigation has been made of the influence of individual linear damping in a stable system of three resonantly interacting waves. Guided by the results from analog computations the exact analytic solution to the undamped system has been extended to cover the damped case by a generalization of the constants of motion. Computations show that the obtained solution gives a good approximation of the waves.
Nonlinear Penetration of a Langmuir Wave into a Plasma Density Gradient
Authors: Kaufman Allan N
Published: January 2007

The nonlinear Schrödinger equation, descriptive of an intense Langmuir wave near critical density, is solved for the steady state of reflection from a linear unperturbed density profile.
Macroscopic Equilibrium Properties of Intense Hollow Relativistic Electron Beams
Authors: Davidson Ronald C , Lebedev Andrei N
Published: January 2007

The equilibrium properties of intense hollow relativistic electron beams are investigated within the framework of a macroscopic cold-fluid model. The electron beam propagates parallel to a uniform magnetic guide field B
0
êz
and is partially charge neutralized and partially current neutralized by a background plasma. In circumstances where the axial velocity profile of the beam is uniform (β
z
=const.) and the angular velocity profile ω(r) is a known function of r, it is shown that all other equilibrium properties (e.g., self-field profiles and beam density profile) can be calculated in closed form. Specific examples of diamagnetic and paramagnetic beam equilibria are discussed.
Collection of Large Amounts of Xenon in Solid Targets
Authors: A Arnesen  , T Noreland  , L-O Norlin
Published: January 2007

Targets containing a considerably higher dose of implanted atoms than earlier reported saturation values have been made with an isotope separator. The collected atoms seem however to be embedded in a carbon layer on the target surface rather than implanted in the target material in the usual sense. For 35 keV xenon ions impinging on iron we have measured concentrations as high as 85 μg/cm2. The targets have been used to determine nuclear magnetic moments and B(E2, 0+ → 2+)-values for even xenon isotopes.
On Aperture Correction in Scanning Interferometry
Authors: Per Nylén
Published: January 2007

The instrument functions of scanning Michelson and Fabry-Perot interferometers in the limiting case of coherence are investigated and characteristics such as the scanning aperture correction and resolving power are analysed. It is shown that there are no essential practical differences in these characteristics from those in the incoherent case.
Lifetime Measurements in Se I and Te I
Authors: Bertil I Dynefors
Published: January 2007

By the beam-foil method a determination has been done of the lifetimes for the terms3S1,1D2,3P2in Se I and3S1,1D2in Te I belonging to the configurationnp3(n+ 1)s. The results are compared to recent relativistic calculations of the transition probabilities.
Characteristics of Pain and Stooling in Children With Recurrent Abdominal Pain
Authors: Shulman Robert J , Eakin Michelle N , Jarrett Monica , Czyzewski Danita I , Zeltzer Lonnie K
Published: January 2007

Objective:

To collect symptom data longitudinally from children with recurrent abdominal pain (RAP) and control (asymptomatic) children.

Patients and Methods:

Children with RAP (n = 77) and controls (n = 33) 7 to 10 years of age completed daily diaries for 2 weeks tracking pain frequency and severity, how often the pain interfered with activities, and stooling pattern.

Results:

RAP children reported a greater number of pain episodes and greater pain severity than control children. Pain commonly was reported to be in the periumbilical area and occurred evenly across the day in both groups. However, the pain interfered with activity more often in the RAP group. There was a positive relationship between pain and interference with activities. Both groups reported stool changes, but there were no differences between groups in stool character (eg, hard, mushy). For both groups, the presence of watery stool was related positively to pain. Of children with RAP, 65% could be categorized as having irritable bowel syndrome, whereas 35% were classifiable as having functional abdominal pain according to the pediatric Rome II criteria.

Conclusions:

To the best of our knowledge, this is the first longitudinal report of symptoms in children with RAP compared with controls. These data demonstrate that there is considerable overlap between children with RAP and control children on a number of items commonly obtained in the history (eg, pain location, timing, stooling pattern). Most children with RAP could be characterized as having irritable bowel syndrome. The relationship between pain reports and interference with activities substantiates the need to deal specifically with the abdominal pain to decrease disability. The relationship between pain and watery stools requires further study.
Nonadherence With Thiopurine Immunomodulator and Mesalamine Medications in Children with Crohn Disease
Authors: Oliva‐Hemker Maria M , Abadom Vivian , Cuffari Carmen , Thompson Richard E
Published: January 2007

Objectives:

To assess the prevalence of adherence to prescribed medications in children with Crohn disease and to identify possible factors associated with nonadherence.

Patients and Methods:

This was a cross‐sectional study of 51 pediatric patients with Crohn disease who were prescribed maintenance therapy with a thiopurine immunomodulator (6‐mercaptopurine or azathioprine) and/or mesalamine during a 180‐day period. Medication adherence rates were calculated from a validated formula using pharmacy records, and nonadherence was defined as a refill rate of <80% of the prescribed medication. Seventy‐five percent of patients were prescribed thiopurine immunomodulators and 86% were prescribed mesalamine.

Results:

The prevalence of nonadherence was 50% for the thiopurine immunomodulators and 66% for mesalamine. The mean number of emergency department visits for patients adherent to mesalamine was significantly greater than the nonadherent group (P < 0.0008). Having an emergency department visit increased the chances of a patient being adherent to mesalamine therapy by >9‐fold (odds ratio, 9.6; 95% confidence interval, 1.87–52.17). The mean number of total health care visits was significantly greater for patients adherent to mesalamine (6.1 ± 0.8) compared with those who were not adherent (3.0 ± 0.4) (P < 0.001).

Conclusions:

These findings suggest that nonadherence to thiopurine immunomodulator or mesalamine therapy in pediatric patients with Crohn disease is common. Having a health care visit was associated with being adherent.
Serum Hepatocyte Growth Factor and Vascular Endothelial Growth Factor in Children with Acute Liver Failure
Authors: Aw Marion M , Mitry Ragai R , Hughes Robin D , Dhawan Anil
Published: January 2007

Objectives:

Hepatocyte growth factor (HGF), a potent mitogen, and vascular endothelial growth factor (VEGF), a potent angiogenic factor, may play roles in hepatocyte regeneration in patients with acute liver failure (ALF). The aim of this study was to investigate serum levels of HGF and VEGF in children with ALF.

Patients and Methods:

Serum samples were collected on admission from 25 children with ALF (median age, 11.1 y; range, 1.3–17.1 y; 11 male, 14 female) and 12 normal children (9.1 y; range, 5.4–15.4 y; 6 male, 6 female). Aetiology of ALF was 13 non‐A to E hepatitis, 3 viral, 3 toxic, and 6 other. HGF and VEGF in sera were assayed by enzyme‐linked immunosorbent assay.

Results:

Median HGF levels in patients (10,157 pg/mL; range, 3412–73,420 pg/mL) were significantly higher than in controls (855 pg/mL, 510–1253 pg/mL; P < 0.001). Median VEGF levels in patients (164 pg/mL, 0–1588 pg/mL) were not significantly different from those in controls (214 pg/mL, 11–527 pg/mL). There was no relationship of HGF or VEGF levels to the aetiology of liver failure. There was a positive correlation between serum HGF and international normalized ratio (r = 0.73, P < 0.001), but not with levels of serum aspartate aminotransferase, bilirubin, or VEGF. There was no correlation between VEGF levels and international normalized ratio, aspartate aminotransferase or bilirubin.

Conclusions:

Serum levels of HGF but not VEGF are increased in children with acute liver failure.
Newcastle disease virus may enter cells by caveolae-mediated endocytosis
Authors: Cantín Celia , Holguera Javier , Ferreira Laura , Villar Enrique , Muñoz-Barroso Isabel
Published: January 2007

The entry into cells of Newcastle disease virus (NDV), a prototype member of the paramyxoviruses, is believed to occur by direct fusion at the plasma membrane through a pH-independent mechanism. In addition, NDV may enter host cells by an endocytic pathway. Treatment of cells with drugs that block caveolae-dependent endocytosis reduced NDV fusion and infectivity, the degree of inhibition being dependent on virus concentration. The inhibitory effect was reduced greatly when drugs were added after virus adsorption. Cells treated with methylβ-cyclodextrin, a drug that sequesters cholesterol from membranes, reduced the extent of fusion, infectivity and virus–cell binding; this indicates that cholesterol plays a role in NDV entry. Double-labelling immunofluorescence assays performed with anti-NDV monoclonal antibodies and antibodies against the early endosome marker EEA1 revealed the localization of the virus in these intracellular structures. Using fluorescence microscopy, it was found that cell–cell fusion was enhanced at low pH. It is concluded that NDV may infect cells through a caveolae-dependent endocytic pathway, suggesting that this pathway could be an alternative route for virus entry into cells.
Influence of interleukin-15 on CD8+ natural killer cells in human immunodeficiency virus type 1-infected chimpanzees
Authors: Rodriguez Annette R. , Arulanandam Bernard P. , Hodara Vida L. , McClure Hazel M. , Cobb Elaine K. , Salas Mary T. , White Robert , Murthy Krishna K.
Published: January 2007

Chimpanzees are susceptible to human immunodeficiency virus type-1 (HIV-1) and develop persistent infection but generally do not progress to full-blown AIDS. Several host and immunological factors have been implicated in mediating resistance to disease progression. Chimpanzees have a higher prevalence of circulating natural killer (NK) cells than humans; however, their role in mediating resistance to disease progression is not well understood. Furthermore, NK cell survival and activity have been shown to be dependent on interleukin-15 (IL-15). Accordingly, the influence of IL-15 on NK cell activity and gamma interferon (IFN-γ) production was evaluated in naive and HIV-1-infected chimpanzees.In vitrostimulation of whole-blood cultures with recombinant gp120 (rgp120) resulted in enhanced IFN-γproduction predominantly by the CD3−CD8+subset of NK cells, and addition of anti-IL-15 to the system decreased IFN-γproduction. Moreover,in vitrostimulation with recombinant IL-15 (rIL-15) augmented IFN-γproduction from this subset of NK cells and increased NK cell cytotoxic activity. Stimulation with rgp120 also resulted in a 2- to 7-fold increase in IL-15 production. These findings suggest that chimpanzee CD3−CD8+NK cells play a vital role in controlling HIV-1 infection by producing high levels of IFN-γ, and that IL-15 elicits IFN-γproduction in this subpopulation of NK cells in HIV-1-infected chimpanzees.
Dual effect of APOBEC3G on Hepatitis B virus
Authors: Noguchi Chiemi , Hiraga Nobuhiko , Mori Nami , Tsuge Masataka , Imamura Michio , Takahashi Shoichi , Fujimoto Yoshifumi , Ochi Hidenori , Abe Hiromi , Maekawa Toshiro , Yatsuji Hiromi , Shirakawa Kotaro , Takaori-Kondo Akifumi , Chayama Kazuaki
Published: January 2007

G to A hypermutation of Hepatitis B virus (HBV) and retroviruses appears as a result of deamination activities of host APOBEC proteins and is thought to play a role in innate antiviral immunity. Alpha and gamma interferons (IFN-α and -γ) have been reported to upregulate the transcription of APOBEC3G, which is known to reduce the replication of HBV. We investigated the number of hypermutated genomes under various conditions by developing a quantitative measurement. The level of hypermutated HBV in a HepG2 cell line, which is semi-permissive for retrovirus, was 2.3 in 104 HBV genomes, but only 0.5 in 104 in permissive Huh7 cells. The level of APOBEC3G mRNA was about ten times greater in HepG2 cells than in Huh7 cells. Treatment of HepG2 cells with either IFN-α or -γ increased the transcription of APOBEC3G and hypermutation of HBV. These mRNAs and hypermutation of HBV genomes were induced more prominently by IFN-γ than by IFN-α. Both IFNs decreased the number of replicative intermediate of HBV. Overexpression of APOBEC3G reduced the number of replicative intermediate of HBV and increased hypermutated genomes 334 times, reaching 968 in 104 genomes. Deamination-inactive APOBEC3G did not induce hypermutation, but reduced the virus equally. Our results suggest that APOBEC3G, upregulated by IFNs, has a dual effect on HBV: induction of hypermutation and reduction of virus synthesis. The effect of hypermutation on infectivity should be investigated further.
Mobility analysis of an NS5A–GFP fusion protein in cells actively replicating hepatitis C virus subgenomic RNA
Authors: Jones Daniel M. , Gretton Sarah N. , McLauchlan John , Targett-Adams Paul
Published: January 2007

We have introduced GFP and photoactivatable GFP into the NS5A coding region of a hepatitis C virus (HCV) subgenomic replicon that gives efficient transient replication. NS5A–GFP, expressed by the replicon, could be detected in cytoplasmic fluorescent foci as early as 4 h after RNA was introduced into cells. The fluorescent foci are likely to be sites where RNA synthesis could occur, although their production was not dependent on prior replication. Photobleaching studies demonstrated that the fluorescent proteins were relatively immobile upon expression from replicon RNAs. By contrast, an NS5A–GFP chimera produced in the absence of other viral proteins was mobile. Hence, interactions in cells expressing HCV replication proteins limit NS5A mobility, and transfer of viral proteins between foci is either slow or does not occur. Thus, the sites of HCV RNA replication possibly have a fixed complement of proteins that may act as discrete factories for producing viral RNA.
Blocks to herpes simplex virus type 1 replication in a cell line, tsBN2, encoding a temperature-sensitive RCC1 protein
Authors: Strang Blair L. , Stow Nigel D.
Published: January 2007

Circularization of the herpes simplex virus type 1 (HSV-1) genome is thought to be an important early event during the lytic cycle. Previous studies from another laboratory using a cell line, tsBN2, that carries a temperature-sensitive mutation in the gene encoding the regulator of chromatin condensation 1 (RCC1) indicated that functional RCC1 was required for HSV-1 genome circularization and subsequent viral DNA synthesis. Here, HSV-1 infection of tsBN2 cells has been re-examined by utilizing both wild-type HSV-1 and a derivative that enables a direct demonstration of circularization. At the non-permissive temperature, when RCC1 was absent, both circularization and viral DNA synthesis were reduced, but not abolished. However, no infectious progeny virus was detected under these conditions. An impairment in the cleavage of concatemeric DNA and the failure to express at least one capsid protein indicated that HSV-1 replication is also blocked at a late stage in the absence of RCC1. This conclusion was supported by a temperature-upshift experiment, which demonstrated a role for RCC1 at times later than 6 h post-infection. Finally, a virus constitutively expressing β-galactosidase produced the protein in a reduced number of cells when RCC1 was inactivated, suggesting that genome delivery to the nucleus or the initial stages of gene expression may also be affected.
Vaccine-based, long-term, stable control of simian/human immunodeficiency virus 89.6PD replication in rhesus macaques
Authors: Yamamoto Hiroyuki , Kawada Miki , Tsukamoto Tetsuo , Takeda Akiko , Igarashi Hiroko , Miyazawa Masaaki , Naruse Taeko , Yasunami Michio , Kimura Akinori , Matano Tetsuro
Published: January 2007

The X4-tropic simian/human immunodeficiency virus (SHIV) 89.6P (or 89.6PD) causes rapid CD4+ T-cell depletion leading to an acute crash of the host immune system, whereas pathogenic R5-tropic simian immunodeficiency virus (SIV) infection, like HIV-1 infection in humans, results in chronic disease progression in macaques. Recent pre-clinical vaccine trials inducing cytotoxic T lymphocyte (CTL) responses have succeeded in controlling replication of the former but shown difficulty in control of the latter. Analysis of the immune responses involved in consistent control of SHIV would contribute to elucidation of the mechanism for consistent control of SIV replication. This study followed up rhesus macaques that showed vaccine-based control of primary SHIV89.6PD replication and found that all of these controllers maintained viraemia control for more than 2 years. SHIV89.6PD control was observed in vaccinees of diverse major histocompatibility complex (MHC) haplotypes and was maintained without rapid selection of CTL escape mutations, a sign of particular CTL pressure. Despite the vaccine regimen not targeting Env, all of the SHIV controllers showed efficient elicitation of de novo neutralizing antibodies by 6 weeks post-challenge. These results contrast with our previous observation of particular MHC-associated control of SIV replication without involvement of neutralizing antibodies and suggest that vaccine-based control of SHIV89.6PD replication can be stably maintained in the presence of multiple functional immune effectors.
Feline caliciviruses (FCVs) isolated from cats with virulent systemic disease possess in vitro phenotypes distinct from those of other FCV isolates
Authors: Ossiboff Robert J. , Sheh Alexander , Shotton Justine , Pesavento Patricia A. , Parker John S. L.
Published: January 2007

During the past decade, several outbreaks of severe systemic disease associated with Feline calicivirus (FCV) have occurred in the USA and the UK. This new disease has caused high mortality in the affected animals and has been termed virulent systemic (VS)-FCV disease. Currently, there are no genetic or in vitro diagnostic methods to distinguish viruses isolated from cases of VS-FCV disease from other isolates. Here, five in vitro properties, as well as the capsid and proteinase–polymerase (pro–pol) sequences, of a set of FCV isolates that included seven isolates from five distinct VS-FCV outbreaks (‘VS isolates’) were investigated. Although all of the FCV isolates investigated had similar kinetics of growth under single-cycle conditions, VS isolates infected tissue-culture cells more efficiently under multiple-cycle growth conditions. Moreover, it was found that cells infected with VS isolates showed cytopathic effects earlier than cells infected with non-VS isolates, although no difference in relative ATP levels were noted at times when morphological changes were first seen. Both VS- and other (non-VS) isolates of FCV demonstrated similar temperature stabilities. Phylogenetic analyses and alignments of the capsid and pro–pol regions of the genome did not reveal any conserved changes that correlated with virulence, and the VS isolates did not segregate into a unique clade. These results suggest that VS isolates have arisen independently several times since first being described and can spread more efficiently in tissue culture than other isolates when infected at low multiplicity.
The slick hair coat locus maps to chromosome 20 in Senepol‐derived cattle
Authors: Mariasegaram M. , Chase C. C. , Chaparro J. X. , Olson T. A. , Brenneman R. A. , Niedz R. P.
Published: January 2007

The ability to maintain normal temperatures during heat stress is an important attribute for cattle in the subtropics and tropics. Previous studies have shown that Senepol cattle and their crosses with Holstein, Charolais and Angus animals are as heat tolerant as Brahman cattle. This has been attributed to the slick hair coat of Senepol cattle, which is thought to be controlled by a single dominant gene. In this study, a genome scan using a DNA‐pooling strategy indicated that the slick locus is most likely on bovine chromosome 20 (BTA20). Interval mapping confirmed the BTA20 assignment and refined the location of the locus. In total, 14 microsatellite markers were individually genotyped in two pedigrees consisting of slick and normal‐haired cattle (n = 36), representing both dairy and beef breeds. The maximum LOD score was 9.4 for a 4.4‐cM support interval between markers DIK2416 and BM4107. By using additional microsatellite markers in this region, and genotyping in six more pedigrees (n = 86), the slick locus was further localized to the DIK4835 ‐ DIK2930 interval.
Change for children? The challenges and opportunities for the children’s social work workforce
Authors: Gupta Anna , Blewett James
Published: January 2007

Children’s services are currently undergoing their biggest changes in a generation. The government is seeking to create a more coherent, seamless configuration of services, with a view to securing improved outcomes for all children. However, there is a current crisis in the recruitment and retention of a range of child welfare professionals, including children’s social workers, which must be addressed in order for this ambitious agenda to be achieved. This paper discusses the findings of a series of focus group discussions with social workers undertaking the London Post Qualifying Child Care Award in response to the Children’s Workforce Strategyconsultation process. These findings are then analysed within the context of the wider literature on social work practice and workforce development. It is argued that central to the debate on how to sustain a competent and stable social work workforce should be consideration of the consequences of initiatives to audit and assess performance; the promotion of relationship‐based social work; and the wider role of social work in preventative and protective services for children.