bluuebunny/crossref_metadata_2025 huggingface dataset:
Relation between Polarization Phenomenon and Space-Charge-Limited Currents in Rutile Single Crystals (TiO2)
Authors: Cardon F.
Published: May 2005

A considerable depolarization current was observed in rutile single crystals. It was ascribed to electrons trapped at the positive electrode in levels which probably exist only in superficial layers of the crystal. The charge piled up corresponds to, at minimum, 1014/cm2 elementary charges e. The dependence of the depolarization current on the depolarization time, I ∼ 1/t, could be explained by assuming that the time dependence is governed by the probability of electron transitions from traps to the conduction band and these under the influence of the strong electric field of the space charge.

Assuming that there are also 1014/cm2 ionized donors at the negative electrode, the observed current-voltage characteristics in thin flakes can be explained by taking into account that this gives rise to a field of the order of 106 V/cm at the negative electrode. Electrons then can enter the crystal by field emission from the negative electrode, but the current will be space-charge-limited in the bulk of the crystal. This explains the observed I ∼ V2 dependence.
Depolarized Components of Light Scattered by Glasses. III. Scattering from General Strain Systems, with Applications to Neutron-Damaged Vitreous Silica
Authors: Goldstein Martin
Published: May 2005

The influence of elastic strains, such as will arise around regions in a glass that have undergone an arbitrary volume expansion, on the components of scattered light of various polarizations is calculated here. The results show that the effect of strains on the scattered intensities can be experimentally separated from the influence of size and shape of the scattering regions. Data on scattering from neutron-damaged vitreous silica are analyzed. The strain scattering is well described by assigning a reasonable value to an optical parameter that appears in the theory. Examination of that component of scattered light associated with the size and shape of the damaged regions reveals some peculiarities perhaps explicable in terms of a wide separation of damaged regions produced by a single primary recoil atom.
Partial Differential Equations with Periodic Coefficients and Bloch Waves in Crystals
Authors: Odeh Farouk , Keller Joseph B.
Published: May 2005

Bloch waves are special solutions of Schrödinger's equation with a periodic real potential. They are plane waves multiplied by periodic functions. In this paper we prove the existence and completeness of Bloch waves and of the related Kohn-Luttinger waves in unbounded domains for a class of partial differential equations which includes the Schrödinger equation. In addition, we discuss the dependence of these waves and the corresponding eigenvalues on the wave vector of the associated plane wave. The results may be interpreted as the analogs for certain partial differential equations of Floquet's theory for ordinary differential equations or as the determination of the spectral representation of certain periodic Hamiltonian operators.
On Scattering of Waves by Objects Imbedded in Random Media: Stochastic Linear Partial Differential Equations and Scattering of Waves by Conducting Sphere Imbedded in Random Media
Authors: Chen Yung Ming
Published: May 2005

A new inhomogeneous linear partial differential equation satisfied by the mean value of the solution of the corresponding inhomogeneous stochastic linear partial differential equation is derived. This new equation has the interesting phenomenon that the differential operators couple with the inhomogeneous terms to form new inhomogeneous terms of the equation. Physically, this means that the randomness of medium and source are coupled together to form new sources. The above approach is then used to derive the equation characterizing wave motions in random media due to random sources. Finally, the problem of scattering of a plane wave by a perfectly conducting sphere of radius a imbedded in a random medium is considered. By utilizing a “pseudopotential” to incorporate the effect of the boundary condition into the reduced wave equation and by the above result, for both ka large and small it is found that up to and including terms of order ε2 (ε = perturbation parameter) the mean value of the scattered field can be calculated from the same deterministic scattering problem with k replaced by an effective propagation constant kñ. The specialization of the new formulation to the problem of scattering of a plane wave by a perfectly conducting semi-infinite space checks with a previous result of Chen.
Note on the Bondi-Metzner-Sachs Group
Authors: Newman E. T. , Penrose R.
Published: May 2005

It is shown that, in space-times which are asymptotically flat, there are reasonable physical restrictions that allow one to impose coordinate conditions (in addition to the usual Bondi-type conditions)which restrict the allowed coordinate group to a subgroup of the Bondi-Metzner-Sachs group. This subgroup is isomorphic to the improper orthochronous inhomogeneous Lorentz group.
Spectrum of the S Operator
Authors: Remler E. A.
Published: May 2005

The structure of a scattering operator which describes events above a three-body and below a four-body threshold has been studied. It is shown that one can approximate it arbitrarily closely in the norm as the sum of two operators, each having a simple form. Using this decomposition, one obtains a general form for the spectral decomposition of this scattering operator.
Properties of Quantum Statistical Expectation Values
Authors: Uhlenbrock D. A.
Published: May 2005

The semigroup of statistical operators, and the unitary group of time translation operators generated by the same Hamiltonian of a nonrelativistic fermion field, are naturally imbedded in a holomorphic half-plane semigroup. The statistical expectation values of products of time-dependent operators are then boundary values of holomorphic functions which allow a Bochner integral representation with a Cauchy kernel. The general time-temperature-dependent Green's functions permit a concise spectral representation. It is suggested that a thermodynamic perturbation theory should treat the Heisenberg and Bloch equations simultaneously in terms of a perturbation theory for holomorphic half-plane semigroups generated by semibounded self-adjoint Hamiltonians.
Some Properties of the Long-Time Values of the Probability Densities for Moderately Dense Gases
Authors: Piccirelli Robert A.
Published: May 2005

It has been argued that, for sufficiently large times, the n-particle probability densities of a moderately dense, simple gas become time-independent functionals of the one-particle probability densities. Proofs are given for several properties of the power series representation of these functionals. In particular, it is shown that the equilibrium value of the n-particle functional is identical to the usual equilibrium probability density term by term, and that the corresponding generalized Boltzmann collision integral vanishes as it should. The Green-Cohen form of the functional is shown to be a formal power series solution of Bogoliubov's functional differential hierarchy. Moreover, a proof is given that the Bogoliubov and Green-Cohen forms of the functional are formally identical term by term. It is argued that the higher terms of these two series probably diverge together.

In the course of the discussion, several new properties of the coefficient operators of the power series for the functional are derived. Moreover, an integral equation for the n-particle functional is derived which may have solutions not representable as functional power series in the one-particle probability density.
Improved Method for Quantum Mechanical Three-Body Problems. II. Repulsive Potentials
Authors: Eyges Leonard
Published: May 2005

We extend a method previously presented for the three-body problem with attractive interparticle potentials to the case of repulsive interparticle potentials, with periodic boundary conditions on each particle. As before, we decompose the wave function into three parts, and from the Schrödinger equation write equations for these parts. We observe that, in one-dimension and for δ-function potentials,these equations can be easily solved numerically, and we present these solutions for potential“strengths” ranging from zero to infinity. We then discuss a more general method for solving these equations, which method involves expansions in a certain set of two-body functions. This general method is not necessarily limited to either one dimension or δ-function potentials, but, as a check on it, we do apply it to that case and get good agreement with the previous numerical results. As a further exploration of the method, we apply it to square well potentials in one dimension. In an Appendix we discuss the set of two-body functions that we use.
High Pressure High Temperature Optical Device
Authors: Balchan A. S. , Drickamer H. G.
Published: May 2005

The high pressure optical cell previously described in the literature has been modified to permit measurements to 400°C and 200 000 atm. The operating details and methods of temperature and pressure calibration are discussed. The absorption edges of sulfur and of olivine are presented as a function of temperature and pressure.
Ballistic Particle Size Separator
Authors: McGinn John H. , MacWaters John T.
Published: May 2005

A new type of instrument for the size classification of airborne particulate matter is described. This apparatus operates on an aerodynamic principle and effects ordered size separation of both liquid and solid particles. Calculations of the spatial separation as a function of size for spherical particles of unit density are in accord with preliminary experimental data for diameters between 10 and 100 μ. Application of this principle to aerosol size-frequency analyses is discussed briefly.
Shielded Coaxial Leads for Low Temperature Electrical Measurements
Authors: Brown Norman L. , Barfield Richard N.
Published: May 2005

The problem of making electrical contact to apparatus at very low temperatures is discussed, with particular reference to dielectric constant measurements in a situation where multiple shielding is required. Examples are given of easily constructed rigid electrode leads suitable for use at low temperatures, which have low thermal conduction,low and stable inter-conductor capacitance and conductance, and which provide for more than two coaxial conductors.
Automatic Constant Signal Plotter
Authors: Cole Arthur
Published: May 2005

The instrument described automatically maps two-dimensional contours of spatial intensity distributions (i.e.,iso-dose, iso-potential, etc.). A fast response detector is driven by two reversible motors, one a scan drive, the other an error compensation drive. Sequential alteration of the roles of the two motors provides complete mapping of continuous or discontinuous contours. Provisions are made to assure 1% recording accuracy. A remote readout recorder allows isolation of the pickup device. Maximum plotting speed is 36 in./min or about 5 min for a family of ten contours in a 10×25-cm area.
Frictionless Recording Torque Magnetometer
Authors: Aldenkamp A. A. , Marks C. P. , Zijlstra H.
Published: May 2005

An instrument for measuring magnetic anisotropy by recording magnetic torque curves is described. The special construction of the transducer which converts the torque exerted on the sample into an electric signal makes it possible to avoid bearings, so that the instrument is essentially free of friction. The instrument is operated with commercially available electronic apparatus and is suitable for routine measurements on large numbers of samples. The maximum sensitivity is 150 d cm per centimeter deflection of the recorder stylus.
Broadband Millimeter Wave Paramagnetic Resonance Spectrometer
Authors: Mock J. B.
Published: May 2005

A flexible magnetic resonance spectrometer is described. Its transmission type microwave structure can be used between 50 and 150 kMc. A modified Varian magnet gives a field of 28 000 gauss, homogeneous to 3 gauss over a typical sample area. A Dewar vessel fits into the 34-in. magnet gap and permits cooling of the sample below theλ point of helium. The millimeter waves are generated by backward wave oscillators, and harmonic conversion is used for the frequency measurement and control. A modification of the spectrometer makes possible the direct measurement of line width and frequency of zero-field lines.
Thermal Property Measurements at Very High Temperatures
Authors: Rasor N. S. , McClelland J. D.
Published: May 2005

Techniques and apparatus have been developed for determination of thermal expansion, specific heat, and thermal conductivity to as high as 3650°C. To obtain and measure the temperatures required, a graphite tube furnace, a graphite helix furnace, and a photoelectric pyrometer were developed and constructed. The details of their design and their use for property determinations to the destruction temperatures of a variety of refractory materials are described.
Improved Gamma Detector using Gamma Moderation
Authors: Fox Raymond
Published: May 2005

Theoretical and experimental results of the effect of gamma moderation are described. A 18-in.-thick sodium iodide crystal and a Co60 gamma source were used to check the increased counting efficiency due to gamma moderation predicted by theory. The gamma source and detector were imbedded in a gamma moderator. The count rate in the gamma moderated system was found to be 6.7 times greater than in the bare system. A counter was designed and built to make the most use of gamma moderation. The results indicate that this counter can be made energy independent or energy dependent, the controlling factor being the size of the gamma moderator surrounding the detector. Though the cost of one of the counter assemblies is less than that of a 1-in.-diam 1-in.-thick sodium iodide crystal plus photomultiplier, the counting efficiency for Na24 gammas is over two times greater.
Permeability and Diffusivity of Hydrogen Through a Palladium Tube
Authors: Katz O. M. , Gulbransen E. A.
Published: May 2005

A palladium diffusion tube which supplies high purity hydrogen was constructed for use in a high vacuum glass system. Temperatures of 213–379°C and back pressures from 1 to 2 atm H2 were used. In this range the permeability was proportional to the square root of pressure and an exponential function of reciprocal temperature. The tube had a long life if it was kept above 150°C while exposed to the gas.

Diffusion coefficients obtained from the permeability experiments were in very good agreement with previous results. The equation for diffusion was DHPd = 4.31×10−3e−5600/RT. The large amounts of hydrogen obtained were reproducible to ±2% of the mean.
High Speed Magnetooptical Measurements on Films
Authors: Archibald P. C. , Conger R. L. , Sharp R. W. , Tomlinson J. L.
Published: May 2005

An electronic strobing magnetooptical apparatus has been developed which makes it possible to observe the magnetization reversal process in thin films with reversal taking place in 1 μsec. Reversal takes place in a non-uniform manner starting at film edges and imperfections.
The influence of predation risk on foraging behaviour of brushtail possums in Australian woodlands
Authors: Pickett Karolyne N. , Hik David S. , Newsome Alan E. , Pech Roger P.
Published: May 2005

The potential effects of predation risk on common brushtail possums were investigated in south-eastern Australian woodlands. Patterns of habitat use, foraging costs using giving-up density (GUD) experiments, and indices of body condition and reproductive success were examined at eight sites in two habitat types (eucalypt- or cypress-pine–dominated stands), within three areas of different red fox abundance (high, moderate and low fox density). In cypress-pine–dominated stands, possums travelled further on the ground, visited more feeding stations and had lower GUDs at feeders where foxes were removed than did possums in high-fox-density sites. In contrast, there was no effect of fox removal on the behaviour of possums in eucalypt-dominated stands. Fox removal also had no effect on indices of body condition and reproduction. Minor effects of microhabitat were detected with trackplot and GUD experiments, but, overall, the results suggest that habitat at the stand-level was more important. The non-lethal effects of foxes in different habitats may need to be taken into account when developing conservation strategies for native marsupials.
Activity patterns and habitat preferences of translocated and resident tiger snakes (Notechis scutatus) in a suburban landscape
Authors: Butler H. , Malone B. , Clemann N.
Published: May 2005

Translocation of snakes is a common practice for managing human–snake conflict in many parts of Australia. The impact of this management on individual snakes is not known. Differences between translocated and non-translocated snakes in terms of their activity patterns and habitat use are likely to indicate an impact on individual snakes from this procedure. We investigated these issues in a suburban parkland close to Melbourne for one of the most familiar of these snakes, the tiger snake (Notechis scutatus). This parkland is frequently used by licenced snake controllers to release snakes that have been removed from nearby private properties at the owner’s request. We used two techniques to assess activity patterns and habitat preferences of resident and translocated snakes: direct observations of tiger snakes that were resident in the park, and radiotelemetry to compare a subset of resident snakes with translocated conspecifics. The size of our transmitters dictated that we only use telemetry for large snakes (≥750 mm snout–vent length), even though the resident population consisted mainly of intermediate-sized females (560–760 mm snout–vent length). Non-telemetred resident snakes were readily observed during spring, but rarely observed in summer and early autumn. Translocated snakes travelled greater distances than resident telemetred snakes, although there was no difference in the frequency of movements. For both groups the degree of cloud cover and maximum daily temperature had a significant influence on daily activity, with snakes being more likely to be active on relatively cool, sunny days. Relative humidity, wind speed and rainfall did not exert a significant influence on activity. Snakes exhibited bimodal peaks in daily activity, avoiding the hottest part of the day. Both resident and translocated snakes showed a preference for grassy woodlands associated with hills, but avoided escarpment woodlands and open plains. Floodplain riparian woodland was avoided by resident snakes, but used in proportion to its availability by translocated snakes. Because translocated snakes released at the study site moved larger distances and showed different habitat preferences to resident snakes we conclude that this practice influences individual snakes. Until the implications of translocation for both snakes and humans are fully understood, we recommend caution in the use of this management practice.
Molecular dynamics and protein function
Authors: Karplus M. , Kuriyan J.
Published: May 2005

A fundamental appreciation for how biological macromolecules work requires knowledge of structure and dynamics. Molecular dynamics simulations provide powerful tools for the exploration of the conformational energy landscape accessible to these molecules, and the rapid increase in computational power coupled with improvements in methodology makes this an exciting time for the application of simulation to structural biology. In this Perspective we survey two areas, protein folding and enzymatic catalysis, in which simulations have contributed to a general understanding of mechanism. We also describe results for the F1ATPase molecular motor and the Src family of signaling proteins as examples of applications of simulations to specific biological systems.
Controlled fabrication of hierarchically branched nanopores, nanotubes, and nanowires
Authors: Meng Guowen , Jung Yung Joon , Cao Anyuan , Vajtai Robert , Ajayan Pulickel M.
Published: May 2005

Here, we report a generic synthetic approach to rationally design multiply connected and hierarchically branched nanopores inside anodic aluminum oxide templates. By using these nanochannels, we controllably fabricate a large variety of branched nanostructures, far more complex than what exists today. These nanostructures include carbon nanotubes and metallic nanowires having several hierarchical levels of multiple branching. The number and frequency of branching, dimensions, and the overall architecture are controlled precisely through pore design and templated assembly. The technique provides a powerful approach to produce nanostructures of greater morphological complexity, which could have far-reaching implications in the design of future nanoscale systems.
Phylogeography of Barbary macaques (
Macaca sylvanus
) and the origin of the Gibraltar colony
Authors: Modolo Lara , Salzburger Walter , Martin Robert D.
Published: May 2005

The Barbary macaque (
Macaca sylvanus
) is the earliest offshoot of the genus
Macaca
and the only extant African representative, all other species being Asiatic. Once distributed throughout North Africa,
M. sylvanus
is now restricted to isolated forest fragments in Algeria and Morocco. The species is threatened; the maximum total wild population size is estimated at 10,000 individuals. Relationships among surviving wild subpopulations in Algeria (96 samples) and Morocco (116 samples) were examined by using 468-bp sequences from hypervariable region I of the mitochondrial DNA control region. Twenty-four different haplotypes were identified, differing by 1-26 mutational steps (0.2-5.6%) and 1 insertion. With one exception (attributable to secondary introduction in coastal Morocco), Algerian and Moroccan haplotypes are clearly distinct. However, whereas Moroccan subpopulations show little divergence in hypervariable region I sequences and little correspondence with geographical distribution, there is a deep division between two main subpopulations in Algeria and one marked secondary division, with haplotypes generally matching geographical distribution. Accepting an origin of the genus
Macaca
of 5.5 million years ago, the Moroccan population and the two main Algerian subpopulations diverged ≈1.6 million years ago. Distinction between Moroccan and Algerian haplotypes permitted analysis of the origin of the Gibraltar colony of Barbary macaques (68 samples; 30% of the population). It is generally held that the present Gibraltar population descended from a dozen individuals imported during World War II. However, the Gibraltar sample was found to include Algerian and Moroccan haplotypes separated by at least 16 mutational steps, revealing a dual origin of the founding females.
Polyclonality of familial murine adenomas: Analyses of mouse chimeras with low tumor multiplicity suggest short-range interactions
Authors: Thliveris Andrew T. , Halberg Richard B. , Clipson Linda , Dove William F. , Sullivan Ruth , Washington Mary Kay , Stanhope Stephen , Newton Michael A.
Published: May 2005

In previous studies demonstrating the polyclonal structure of familial intestinal adenomas, high tumor multiplicity made it difficult to eliminate the possibility that polyclonality arose by the random collision of distinct initiated clones as opposed to some form of clonal interaction. We sought to test further the random collision hypothesis. Chimeric mice carrying the multiple intestinal neoplasia (Min) mutation of the adenomatous polyposis coli gene (Apc) and homozygous for the tumor resistance allele of theMom1locus were established. These chimeras also display a strong propensity for tumors of polyclonal structure, despite their markedly reduced tumor multiplicity. Considering tumor sizes and multiplicities, the observed fraction of overtly polyclonal heterotypic adenomas was significantly higher than predicted by the random collision hypothesis. This finding supports models of polyclonality involving interaction among multiple initiated clones. The extent of clonal interaction was assessed by statistical analyses that relate the observed frequency of overtly polyclonal heterotypic tumors to the geometry of the chimeric patches and the pattern of underlying crypts. These statistical calculations indicate that the familial adenomas of theApcMin/+mouse may commonly form through interactions between clones as close as 1–2 crypt diameters apart.
Interactions between the solitary endoparasitoid, Meteorus gyrator (Hymenoptera: Braconidae) and its host, Lacanobia oleracea (Lepidoptera: Noctuidae), infected with the entomopathogenic microsporidium, Vairimorpha necatrix (Microspora: Microsporidia)
Authors: Down R.E. , Smethurst F. , Bell H.A. , Edwards J.P.
Published: May 2005

Infection of Lacanobia oleracea(Linnaeus) larvae with the microsporidium Vairimorpha necatrix(Kramer) resulted in significant effects on the survival and development of the braconid parasitoid, Meteorus gyrator(Thunberg). Female M. gyrator did not show any avoidance of V. necatrix-infected hosts when they were selecting hosts for oviposition. When parasitism occurred at the same time as infection by the pathogen, or up to four days later, no significant detrimental effects on the parasitoid were observed. However, when parasitism occurred six to eight days after infection, a greater proportion(12.5–14%) of hosts died before parasitoid larvae egressed. Successful eclosion of adult wasps was also reduced. When parasitism and infection were concurrent, parasitoid larval development was significantly faster in infected hosts, and cocoons were significantly heavier. However, as the time interval between infection and parasitism increased, parasitoid larval development was significantly extended by up to two days, and the cocoons formed were significantly (c. 20%) smaller. Vairimorpha necatrix spores were ingested by the developing parasitoid larvae, accumulated in the occluded midgut, and were excreted in the meconium upon pupation.
The incretins: a link between nutrients and well-being
Authors: Burcelin Rémy
Published: May 2005

The glucoincretins, glucagon-like peptide-1 (GLP-1) and gastric inhibitory peptide (GIP), are intestinal peptides secreted in response to glucose or lipid intake. Data on isolated intestinal tissues, dietary treatments and knockout mice strongly suggest that GIP and GLP-1 secretion requires glucose and lipid metabolism by intestinal cells. However, incretin secretion can also be induced by non-digestible carbohydrates and involves the autonomic nervous system and endocrine factors such as GIP itself and cholecystokinin. The classical pharmacological approach and the recent use of knockout mice for the incretin receptors have shown that a remarkable feature of incretins is the ability to stimulate insulin secretion in the presence of hyperglycaemia only, hence avoiding any hypoglycaemic episode. This important role is the basis of ongoing clinical trials using GLP-1 analogues. Since most of the data concern GLP-1, we will focus on this incretin. In addition, GLP-1 is involved in glucose sensing by the autonomic nervous system of the hepato-portal vein controlling muscle glucose utilization and indirectly insulin secretion. GLP-1 has been shown to decrease glucagon secretion, food intake and gastric emptying, preventing excessive hyperglycaemia and overfeeding. Another remarkable feature of GLP-1 is its secretion by the brain. Recently, elegant data showed that cerebral GLP-1 is involved in cognition and memory. Experiments using knockout mice suggest that the lack of the GIP receptor prevents diet-induced obesity. Consequently, macronutrients controlling intestinal glucose and lipid metabolism would control incretin secretion and would consequently be beneficial for health. The control of incretin secretion represents a major goal for new therapeutic as well as nutrition strategies for treating and/or reducing the risk of hyperglycaemic syndromes, excessive body weight and thus improvement of well-being.
Inulin and oligofructose: impact on intestinal diseases and disorders
Authors: Guarner Francisco
Published: May 2005

A large and diverse variety of bacteria have evolved and adapted to live in the human intestinal habitat in a symbiotic arrangement that influences both physiology and pathology in the host. Symbiosis between host and flora can be optimised by prebiotics. Inulin-type fructans have been shown to improve the metabolic functions of the commensal flora. Clinical and experimental data suggest that they also improve the gut mucosal barrier. Furthermore, modulation of the trophic functions of the flora by these prebiotics could help in the prevention of inflammatory bowel diseases. The anti-inflammatory effects of inulin or oligofructose have been assessed in the rat model of distal colitis induced by dextran sodium sulphate, which histologically resembles human ulcerative colitis, and in the trinitrobenzene sulphonic acid model that resembles human Crohn's disease. Both inulin and oligofructose stimulate colonic production of SCFA and favour the growth of indigenous lactobacilli and/or bifidobacteria. These effects are associated with reduced mucosal inflammation and decreased mucosal lesion scores. Inulin has also been tested in a placebo-controlled clinical trial in patients with relapsing pouchitis. Treatment reduced endoscopic and histological parameters of inflammation of the pouch mucosa. Inulin and oligofructose may offer an opportunity to prevent chronic inflammatory intestinal disorders, and this potential should be tested in
further clinical studies.
Behavioural and cognitive effects of oligofructose-enriched inulin in rats
Authors: Messaoudi Michaël , Rozan Pascale , Nejdi Amine , Hidalgo Sophie , Desor Didier
Published: May 2005

The behavioural and cognitive effects of oligofructose-enriched inulin at the doses of 5 and 10% in the diet, orally ingested daily during 2 weeks, wereinvestigated using a functional observational battery (FOB) and the light extinction test in male Wistar rats. Control rats received a standard diet and were tested in the same test situations. The behavioural effects were assessed 2 d before and 14 d after the beginning of the treatment period and the cognitive effects were investigated after the administration period by lever-pressing activity and learning discrimination using the light extinction test paradigm. In general, the study demonstrated that oligofructose-enriched inulin at 5% in the diet, and particularly at 10% in the diet, caused relaxing-like effects, stimulated and increased the general activity and interest of the rats to the test environment. In addition, both doses of oligofructose-enriched inulin showed significant effects on learning discrimination in male rats, in comparison with the control diet. These results suggest that oligofructose-enriched inulin, particularly at the dose of 10 %, improves cognitive performances in the light extinction test and the well-being of male rats using the FOB.
Inulin, oligofructose and bone health: experimental approaches and mechanisms
Authors: Weaver Connie M.
Published: May 2005

Inulin-type fructans have been proposed to benefit mineral retention, thereby enhancing bone health. Many, but not all, experimental animal studies have shown increased mineral absorption by feeding non-digestible oligosaccharides. Possible reasons for inconsistencies are explored.A few studies have reported an enhanced bone mineral density or content. Bone health can be evaluated in chronic feeding studies with bone densitometry, bone breaking strength, bone mineral concentration and bone structure. Isotopic Ca tracers can be used to determine the point of metabolism affected by feeding a functional food ingredient. These methods and the effects of feeding inulin-type fructose are reviewed. Inulin-type fructans enhance Mg retention. Chicory long-chain inulin and oligofructose enhance femoral Ca content, bone mineral density and Ca retention through enhanced Ca absorption and suppressed bone turnover rates, but it is not bone-promoting under all conditions
Reliability and validity of a questionnaire to measure personal, social and environmental correlates of fruit and vegetable intake in 10–11-year-old children in five European countries
Authors: De Bourdeaudhuij I , Klepp K-I , Due P , Rodrigo C Perez , de Almeida MDV , Wind M , Krølner R , Sandvik C , Brug J
Published: May 2005

Objectives

To investigate the internal consistency of the scales and the test–retest reliability and predictive validity of behaviour theory-based constructs measuring personal, social and environmental correlates of fruit and vegetable intake in 10–11-year-old children.

Design

Test–retest with one-week interval.

Setting

Five European countries: Norway, Spain, Denmark, Portugal, Belgium.

Subjects

Three hundred and twenty-six children completed the questionnaire during class hours.

Results

For the total sample across all countries, the test–retest reliability was good to very good (intra-class correlation coefficient (ICC) >0.60) for 12 out of the 15 fruit constructs and also for 12 out of the 15 vegetable constructs. Acceptable ICCs, ranging between 0.50 and 0.59, were found for the remaining constructs. Test–retest reliability was comparable across countries. Only in Portugal were some significantly lower ICCs found for some constructs (knowledge and barriers related to fruit, general self-efficacy related to fruit and vegetables) compared with the other countries. Cronbach'sαvalues were moderate to high (range 0.52 to 0.89) with the exception of the general self-efficacy scale, which had a value below 0.50 for both fruit (α= 0.42) and vegetables (α= 0.49). Spearman correlations with intake ranged between -0.16 and 0.54 for personal determinants and between 0.05 and 0.38 for environmental determinants. Compared with other studies, predictive validity can be considered moderate to good.

Conclusions

The questionnaire provides a reliable, valid and easy-to-administer tool for assessing personal, social and environmental factors of potential influence on fruit and vegetable intake in 10–11-year-olds.
Overweight in urban, low-income, African American and Hispanic children attending Los Angeles elementary schools: research stimulating action
Authors: Slusser Wendelin M , Cumberland William G , Browdy Ben L , Winham Donna M , Neumann Charlotte G
Published: May 2005

Objective

This study was undertaken to establish the prevalence and severity of nutritional problems among low-income children of elementary school age in the Los Angeles Unified School District (LAUSD) in order to collect baseline data to inform policy-makers.

Design and methods

A cross-sectional survey of children in 14 elementary schools was conducted from January to June, 1998. Nine hundred and nineteen children were measured and interviewed. The planning, design and data analysis were carried out in collaboration with key LAUSD policy-makers.

Results

More than 35% of the sample was classified as being at risk for overweight or overweight according to body mass index.

Conclusion

There is a high prevalence of children who are at risk for overweight or who are overweight in Los Angeles. This finding has triggered the development of multiple school-based intervention programmes.
Reproducibility of a short semi-quantitative food group questionnaire and its performance in estimating nutrient intake compared with a 7-day diet diary in the Million Women Study
Authors: Roddam Andrew W , Spencer Elizabeth , Banks Emily , Beral Valerie , Reeves Gillian , Appleby Paul , Barnes Isobel , Whiteman David C , Keyal Timothy J
Published: May 2005

Objectives

To assess the short- and long-term reproducibility of a short food group questionnaire, and to compare its performance for estimating nutrient intakes in comparison with a 7-day diet diary.

Design

Participants for the reproducibility study completed the food group questionnaire at two time points, up to 2 years apart. Participants for the performance study completed both the food group questionnaire and a 7-day diet diary a few months apart. Reproducibility was assessed by kappa statistics and percentage change between the two questionnaires; performance was assessed by kappa statistics, rank correlations and percentages of participants classified into the same and opposite thirds of intake.

Setting

A random sample of participants in the Million Women Study, a population-based prospective study in the UK.

Subjects

In total, 12 221 women aged 50–64 years.

Results

In the reproducibility study, 75% of the food group items showed at least moderate agreement for all four time-point comparisons. Items showing fair agreement or worse tended to be those where few respondents reported eating them more than once a week, those consumed in small amounts and those relating to types of fat consumed. Compared with the diet diary, the food group questionnaire showed consistently reasonable performance for the nutrients carbohydrate, saturated fat, cholesterol, total sugars, alcohol, fibre, calcium, riboflavin, folate and vitamin C.

Conclusions

The short food group questionnaire used in this study has been shown to be reproducible over time and to perform reasonably well for the assessment of a number of dietary nutrients.
Effect of iron supplementation on mental and motor development in children: systematic review of randomised controlled trials
Authors: Sachdev HPS , Gera Tarun , Nestel Penelope
Published: May 2005

Objective

To evaluate the effect of iron supplementation on mental and motor development in children through a systematic review of randomised controlled trials (RCTs).

Data sources

Electronic databases, personal files, hand search of reviews, bibliographies of books, abstracts and proceedings of international conferences.

Review methods

RCTs with interventions that included oral or parenteral iron supplementation, fortified formula milk or cereals were evaluated. The outcomes studied were mental and motor development scores and various individual development tests employed, including Bayley mental and psychomotor development indices and intelligence quotient.

Results

The pooled estimate (random effects model) of mental development score standardised mean difference (SMD) was 0.30 (95% confidence interval (CI) 0.15 to 0.46,P< 0.001;P< 0.001 for heterogeneity). Initial anaemia and iron-deficiency anaemia were significant explanatory variables for heterogeneity. The pooled estimate of Bayley Mental Development Index (weighted mean difference) in younger children (<27 months old) was 0.95 (95% CI −0.56 to 2.46,P= 0.22;P= 0.016 for heterogeneity). For intelligence quotient scores (≥8 years age), the pooled SMD was 0.41 (95% CI 0.20 to 0.62,P< 0.001;P= 0.07 for heterogeneity). There was no effect of iron supplementation on motor development score (SMD 0.09, 95% CI -0.08 to 0.26,P= 0.28;P= 0.028 for heterogeneity).

Conclusions

Iron supplementation improves mental development score modestly. This effect is particularly apparent for intelligence tests above 7 years of age and in initially anaemic or iron-deficient anaemic subjects. There is no convincing evidence that iron treatment has an effect on mental development in children below 27 months of age or on motor development.
The CATCH Kids Club: a pilot after-school study for improving elementary students’ nutrition and physical activity
Authors: Kelder Steve , Hoelscher Deanna M , Barroso Cristina S , Walker Joey L , Cribb Peter , Hu Shaohua
Published: May 2005

Background

Although many school-based diet and physical activity interventions have been designed and evaluated, relatively few have been tested for the after-school setting. After-school day-care programmes at either elementary schools or private locations provide a ready-made opportunity for health programmes that may be difficult to incorporate into an already-full school day. The purpose of this paper is to report on a pilot study of an after-school adaptation of the CATCH (Coordinated Approach To Child Health) elementary school programme called the CATCH Kids Club (CKC).

Methods

The CKC was pilot-tested and formatively evaluated in 16 Texas after-school programmes: eight in El Paso and eight in Austin (four intervention and four reference sites each). Evaluation consisted of direct observation of moderate to vigorous physical activity during play time, self-reported food intake and physical activity, and focus group interviews with after-school programme staff.

Results

Students responded well to the physical activity and snack components and were less interested in the five-module education component. Routine staff training was a key variable in achieving proper implementation; the ideal would be a full day with repeated follow-up model teaching visits. Staff turnover was a logistic issue, as was programme leader readiness and interest in conducting the programme. Strong and significant effects were observed for the physical activity but not for the education component. The results of the physical education component suggest it is feasible, effective and ready for larger-scale evaluation or dissemination.
Balancing between costs and benefits of maternal hormone deposition in avian eggs
Authors: Groothuis Ton G. G , Eising Corine M , Dijkstra Cor , Müller Wendt
Published: May 2005

Avian eggs contain substantial amounts of maternal androgens, and several studies have indicated that these are beneficial for the chick. Nevertheless, there is a large and systematic variation in maternal hormone concentrations both within and between clutches. If maternal androgens also involve costs, this might explain why not all mothers put high levels of androgens in their clutches. However, the simultaneous occurrence of both benefits and costs has not yet been convincingly demonstrated. We show experimentally that yolk androgens suppress immune function and simultaneously stimulate growth in black-headed gull chicks. Thus, mothers face a trade-off between these costs and benefits and may tune hormone deposition to prevailing conditions that influence chick survival.
Roosts as information centres: social learning of food preferences in bats
Authors: Ratcliffe John M , ter Hofstede Hannah M
Published: May 2005

The short-tailed fruit bat,
Carollia perspicillata
, lives in groups in tree hollows and caves. To investigate whether these roosts might serve as information centres, we tested whether individuals' preferences for novel foods could be enhanced through social learning at the roost. We also determined whether socially learned preferences for novel foods were reversed through interaction with other roost mates by simulating changes in available food resources such as those associated with variations in timing of fruit production in different plant species. Bats exhibited socially induced preferences that were readily reversible. We suggest that for frugivorous bats, roosts can serve as centres for information exchange about novel and familiar, ephemeral foods without requiring conspecific recruitment to these resources.
Identifying contact zone hotspots of passerine birds in the Palaearctic region
Authors: Aliabadian Mansour , Roselaar Cees S , Nijman Vincent , Sluys Ronald , Vences Miguel
Published: May 2005

Birds are known to be a group rich in pairs of closely related species that have parapatric or allopatric distributions with relatively narrow contact zones. Here we analyse the geographical distribution of these contact zones for parapatric species pairs of passerine birds of the Palaearctic region. Their contact zones are located mainly in southwestern, northern and central-southern Asia, and in northwestern Africa, with a hotspot in the Middle East. A mid-domain effect null model, where contact zone hotspots are a neutral correlate of continental geometry, had a low explanatory power of 3.8%; the observed distribution of contact zones was not sufficiently predicted. Hypotheses involving range contractions and secondary contact in areas of high topographic and habitat diversity may offer more convincing explanations and offer promising perspectives for future studies.
The ecology and evolution of patience in two New World monkeys
Authors: Stevens Jeffrey R , Hallinan Elizabeth V , Hauser Marc D
Published: May 2005

Decision making often involves choosing between small, short-term rewards and large, long-term rewards. All animals, humans included, discount future rewards—the present value of delayed rewards is viewed as less than the value of immediate rewards. Despite its ubiquity, there exists considerable but unexplained variation between species in their capacity to wait for rewards—that is, to exert patience or self-control. Using two closely related primates—common marmosets (
Callithrix jacchus
) and cotton-top tamarins (
Saguinus oedipus
)—we uncover a variable that may explain differences in how species discount future rewards. Both species faced a self-control paradigm in which individuals chose between taking an immediate small reward and waiting a variable amount of time for a large reward. Under these conditions, marmosets waited significantly longer for food than tamarins. This difference cannot be explained by life history, social behaviour or brain size. It can, however, be explained by feeding ecology: marmosets rely on gum, a food product acquired by waiting for exudate to flow from trees, whereas tamarins feed on insects, a food product requiring impulsive action. Foraging ecology, therefore, may provide a selective pressure for the evolution of self-control.
Macaques (Macaca nemestrina) recognize when they are being imitated
Authors: Paukner Annika , Anderson James R , Borelli Eleonora , Visalberghi Elisabetta , Ferrari Pier F
Published: May 2005

This study investigated whether monkeys recognize when a human experimenter imitates their actions towards an object. Two experimenters faced 10 pigtailed macaques, who were given access to an interesting object. One experimenter imitated the monkeys' object-directed actions, the other performed temporally contingent but structurally different object-directed actions. Results show a significant visual preference for the imitator during manual object manipulations, but not mouthing actions. We argue that the ability to match actions could be based on both visual–visual and kinaesthetic–visual matching skills, and that mirror neurons, which have both visual and motor properties, could serve as a neural basis for recognizing imitation. However, imitation recognition as assessed by visual preference does not necessarily imply the capacity to attribute imitative intentionality to the imitator. The monkeys might implicitly recognize when they are being imitated without deeper insight into the mental processes of others.
Distribution of mercury and methylmercury in the sediments of a lowland river system
Authors: Birkett Jason W , Lester John N
Published: May 2005

Concentrations of total mercury (T-Hg) and methylmercury (MeHg) were determined in surficial sediments from the River Yare, Norfolk, UK over the period 1986–1998, to assess the temporal and spatial trends of contamination arising from a historical point source discharge. The results demonstrate that the spatial distribution pattern follows that of a distinct pollution plume in the sediments with an initial increase 2–3 km downstream from the point source discharge at Whitlingham sewage treatment works (STW) outfall. Temporally, this pollution plume remains evident, although there has been an overall decline in the mean T-Hg concentrations from 5.4 in 1986 to 1.8 mg kg
−1
in 1998. The major factor for this improvement has been the reduction in discharge of metals from the STW, together with burial by a fresh overlay of uncontaminated sediments.

MeHg concentrations also exhibited a dispersed pollution plume. Mean concentrations of MeHg fluctuated during the study period between 3.3 and 8.5 μg kg
−1
. There has been no concomitant decline in MeHg concentrations over this period. MeHg was found to constitute less than 1% of T-Hg concentrations in the sediments. The weak correlations observed between T-Hg and MeHg concentrations indicate external environmental factors have a significant influence on determining MeHg concentrations in the sedimentary compartment.