bluuebunny/crossref_metadata_2025 huggingface dataset:
Linear optical properties of a Ti-SiO2 nanoparticle composite
Authors: Zhao J. P. , Chen Z. Y. , Lu M. , Rabalais J. W.
Published: December 2002

We report the linear optical properties of a titanium nanoparticle composite formed by implantation of low energy Ti+ into single crystalline SiO2. A surface plasmon resonance (SPR) induced absorption band is found in the 650–850 nm wavelength range, i.e., in the visible (red) and near infrared regions, indicating the formation of Ti nanoparticles in the subsurface layer of the SiO2 matrix. The average size of the particles is ∼2.6 nm and the volume fraction is as low as 0.016. At the implantation energy of 9 keV and total dose of 3×1016 ions/cm2, the SPR absorption band becomes distinguishable only at temperatures greater than 600 °C and reaches its maximum at ∼800 °C (1/2Tm). Enhanced nucleation with nearly constant particle size with increasing temperature contributes to the increased SPR absorption intensity at temperatures ⩽800 °C. The SPR absorption intensity decreases significantly near 1000 °C (2/3Tm). A blueshift of the SPR absorption maximum with substrate temperature is also observed. The shape of the SPR absorption band and the difference between low and high energy implantations is discussed.
On correlated heterogeneities of glass-forming liquids
Authors: Bakai A. S.
Published: December 2002

The thermodynamics and structure of glass-forming liquids are considered within the framework of the heterophase fluctuation (HPF) model. The main goal of the theory developed is to find a description for the long-range correlations (LRC) of the density fluctuations known as the Fischer cluster. The van der Waals approximation of the HPF model shows that the liquid can have an isolated solid–fluid critical point analogous to the critical point of a gas–liquid system. Heterophase fluctuations in the form of solidlike noncrystalline and fluidlike clusters can have LRC in a narrow vicinity of the critical point. An analysis shows that the properties of the conventional critical fluctuations differ from those of the Fisher cluster. This forces one to look for another explanation of the observed LRC in glass-forming liquids. Large configurational entropy of liquids and glasses is a manifestation of multiplicity of the short-range ordering of molecules in the amorphous solidlike and fluidlike clusters. The multiplicity of short-range order results in structural heterogeneities. Random-field Ginzburg–Landau equations for the HPFs are deduced taking into account the structural heterogeneities. The random field is generated by these heterogeneities. It is found that at least three characteristic correlation scales are inherent to the HPFs: the radius of local order, r0, which is comparable with the radius of the first coordination sphere; the random-field-controlled radius of critical fluctuations, Rc; the average correlation length ξav of fractal aggregations formed by the correlated domains (the domains have size ∼Rc). The length ξav is the characteristic size of the Fischer cluster. The conditions for the appearance of the listed correlations are deduced by requiring that they provide minimization of the free energy of the system. The annealing kinetics and dynamics (the ultraslow modes) of the Fischer cluster are described.
Resonant surface waves and instabilities in finite β plasmas
Authors: Taroyan Y. , Erdélyi R.
Published: December 2002

Magnetohydrodynamic surface waves are studied at an interface of finite thickness separating two homogeneous arbitrary finite β plasmas which are in parallel motion with respect to each other and are permeated by parallel magnetic fields. It is assumed that the density decreases and the magnetic field strength increases across the interface. The model is representative of the mantle-like boundary layer separating the fast flowing magnetosheath from the tail region of the magnetosphere. All existing wave modes are classified, their main properties are investigated, and analytical expressions for critical velocities are obtained. The resonant flow instability (RFI) and Kelvin–Helmholtz instability are studied when the finite thickness of the inhomogeneous boundary layer is taken into account. The theory of negative energy waves is applied to predict the behavior and interactions of the surface modes in such plasmas. Growth rates of RFIs are examined under various conditions. The dependence of critical velocities on the density ratio is studied under the assumption of a nonuniform magnetic field resulting in different plasma β on both sides of the inhomogeneous layer. Possible observational signatures of the RFI are also discussed.
Molecular etiology of gut malformations and diseases
Authors: De Santa Barbara Pascal , Van Den Brink Gijs Robert , Roberts Drucilla Jane
Published: December 2002

This review describes recent advances using animal models in the analysis of the molecular controls of gastrointestinal development, with specific attention to mutations causing maldevelopment similar to those seen in human gut malformations. By focusing on specific human gut pathologic conditions and maldevelopment, we describe the probable roles of signaling pathways, including the hedgehog pathway, the bone morphogenic protein pathway, and the role of the homeotic genes. © 2002 Wiley‐Liss, Inc.
Chromosomal abnormalities in human glioblastomas: Gain in chromosome 7p correlating with loss in chromosome 10q
Authors: del Mar Inda María , Fan Xing , Muñoz Jorge , Perot Christine , Fauvet Didier , Danglot Giselle , Palacio Ana , Madero Pilar , Zazpe Idoya , Portillo Eduardo , Tuñón Teresa , Martínez‐Peñuela José María , Alfaro Jorge , Eiras José , Bernheim Alain , Castresana Javier S.
Published: December 2002

Various genomic alterations have been detected in glioblastoma. Chromosome 7p, with the epidermal growth factor receptor locus, together with chromosome 10q, with the phosphatase and tensin homologue deleted in chromosome 10 and deleted in malignant brain tumors‐1 loci, and chromosome 9p, with the cyclin‐dependent kinase inhibitor 2A locus, are among the most frequently damaged chromosomal regions in glioblastoma. In this study, we evaluated the genetic status of 32 glioblastomas by comparative genomic hybridization; the sensitivity of comparative genomic hybridization versus differential polymerase chain reaction to detect deletions at the phosphatase and tensin homologue deleted in chromosome 10, deleted in malignant brain tumors‐1, and cyclin‐dependent kinase inhibitor 2A loci and amplifications at the cyclin‐dependent kinase 4 locus; the frequency of genetic lesions (gain or loss) at 16 different selected loci (including oncogenes, tumor‐suppressor genes, and proliferation markers) mapping on 13 different chromosomes; and the possible existence of a statistical association between any pair of molecular markers studied, to subdivide the glioblastoma entity molecularly. Comparative genomic hybridization showed that the most frequent region of gain was chromosome 7p, whereas the most frequent losses occurred on chromosomes 10q and 13q. The only statistically significant association was found for 7p gain and 10q loss. © 2002 Wiley‐Liss, Inc.
Characterization of a new family of proteins that interact with the C‐terminal region of the chromatin‐remodeling factor CHD‐31
Authors: Lemos Taı́la A. , Passos Dario O. , Nery Flávia C. , Kobarg Jörg
Published: December 2002

The two human proteins Ki‐1/57 and CGI‐55 have highly similar amino acid sequences but their functions are unknown. We analyzed them by yeast two‐hybrid screens and found that they interact with the C‐terminal region of the human chromatin‐remodeling factor CHD‐3 (chromo‐helicase‐DNA‐binding domain protein‐3). The interaction of CGI‐55 and CHD‐3 could be confirmed in vitro and in vivo by co‐immunoprecipitations from Sf9 insect cells. Mapping showed that CGI‐55 interacts with CHD‐3 via two regions at its N‐ and C‐terminals. The CGI‐55 and Ki‐1/57 mRNAs show highest expression in muscle, colon and kidney. A CGI55–GFP fusion protein was localized in the cytoplasm, nucleus and perinuclear regions of HeLa cells. These data suggest the possibility that CGI‐55 and Ki‐1/57 might be involved in nuclear functions like the remodeling of chromatin.
MTO: the second member of a Drosophila dual copper‐thionein system
Authors: Domenech J. , Palacios O. , Villarreal L. , González-Duarte P. , Capdevila M. , Atrian S.
Published: December 2002

Drosophila MTO metal binding features were analyzed for comparison with MTN, the paralogous Drosophila metallothionein, and to classify MTO as either zinc‐ or copper‐thionein. This was achieved by a combination of in vivo, in vitro and in silico methodologies. All the results unambiguously classified MTO as a second Drosophila copper‐thionein, putting Drosophila forward as the only metazoan in which any zinc‐thionein has still to be reported. Interestingly, experimental data only showed minor differences in the coordinative behavior of both MTs, but provided a characteristic spectroscopic fingerprint, revealing the possible binding of chloride anions in certain metal‐MTO aggregates.
Service utilisation and costs of first-contact patients in a community psychiatric service in Italy
Authors: Percudani Mauro , Fattore Giovanni , Belloni Gian Carlo , Gerzeli Simone , Contini Agostino
Published: December 2002

This study describes service utilisation under routine clinical activity and the costs of providing mental health care for 24 months for the whole population of 330 subjects who had first contact with the Magenta Community Mental Health Centre during one year. The mean age of patients was 42.5 years, and 61% were females. According to ICD 10 criteria, 7% were diagnosed as having schizophrenia, 22% mood disorders, 37% neurotic disorders, 15% personality disorders and 19% other diagnoses. The clinical routine activity was monitored for 24 months from the first contact for each patient. The mean cost for a schizophrenic patient is more than double that of other patients. In-patient activity and community services accounted, respectively, for 49.7% and 50.3% of the total costs. Total health care costs per patient differ widely according to whether patients had been hospitalised during the observation period. Patients with a previous psychiatric contact and a longer duration of illness were more costly than the other patients. Multiple regression analysis was used to assess the association between all the individual variables and costs. For the whole population, the model explains 50% of the cost variation. Higher treatment costs were positively associated with the presence of previous psychiatric contacts and referral to the CPS by other sources than a general practitioner, and negatively associated with age.
Irreversibility and Limiting Possibilities of Macrocontrolled Systems I: Thermodynamics
Authors: Tsirlin A. M. , Kazakov V. , Kolinko N. A.
Published: December 2002

In this paper, two types of systems — thermodynamic and economic — are considered, which include a large number of micro subsystems and are controlled on the macro level (macrocontrolled systems). The analogy between the maximal work problem in thermodynamics and the maximal profit problem in a microeconomic system is investigated. The notion of exergy is generalized for the systems which do not contain reservoirs, and the conditions of maximal power of heat engines are generalized for systems with arbitrary structure. The notion of system profitability and the measure of irreversibility of an microeconomic processes are introduced. The extremal principle which determines an equilibrium state of open microeconomic system, is formulated. The conditions of optimality of resource trading and the expression for profitability of resource exchange are formulated for systems which include market with perfect competition, and for systems which do not include it. Economic analogues of the second law of thermodynamics are formulated using introduced concepts. The first part of the paper is devoted to thermodynamic systems and the second to microeconomic systems.
2001 SEYMOUR B. SARASON AWARD ADDRESS: The Spirit of Community Psychology
Authors: Kelly James G.
Published: December 2002

Community psychology as a field may have lost some of its original spirit; a spirit dominant at the founding of the field. Spirit is a difficult concept to discuss since it is a concept beyond usual discourse in psychology as a denotative, measurable and verifiable concept. Taking the lead from William James, Spirit, however elusive, is most essential to a sense of self. I offer three suggestions to enhance and to make our individual and collective spirit more vital: (1) Continuing education in the history of community psychology; (2) Creating time to share stories about our work; (3) Creating safe settings to enlarge our spirit. These ideas are offered as pragmatic suggestions to enable us to create more coherence between our personal and professional selves.
Type II Citrullinaemia (Citrin Deficiency) in a Neonate with Hypergalactosaemia Detected by Mass Screening
Authors: Naito E. , Ito M. , Matsuura S. , Yokota I. , Saijo T. , Ogawa Y. , Kitamura S. , Kobayashi K. , Saheki T. , Nishimura Y. , Sakura N. , Kuroda Y.
Published: December 2002

Type II citrullinaemia (CTLN2) is an adult‐ or late childhood‐onset liver disease characterized by a liver‐specific defect in argininosuccinate synthetase protein. The enzyme abnormality is caused by deficiency of the protein citrin, which is encoded by the SLC25A13 gene. Until now, however, few cases with SLC25A13 mutations have been reported in children with liver disease. We describe an infant who presented with neonatal hepatitis in association with hypergalactosaemia detected by neonatal mass screening. DNA analysis of SLC25A13 revealed that the patient was homozygous for a IVS11+1G>A mutation. This case suggests that SLC25A13 mutant should be suspected in neonatal patients with hypergalactosaemia of unknown cause.
Promotion of Social Change: A Conceptual Framework
Authors: Tseng Vivian , Chesir-Teran Daniel , Becker-Klein Rachel , Chan May L. , Duran Valkiria , Roberts Ann , Bardoliwalla Nenshad
Published: December 2002

This paper argues for the need to advance promotion efforts and proposes a conceptual framework forpromotion of social change. A brief review is presented of traditional frameworks for the prevention of mental and social disorders and the promotion of wellness and social competencies, with attention to the ways in which promotion of social change extends and departs from these frameworks. In a framework for promoting social change, we advocate for promoting dynamic processes within systems, rather than outcomes within individuals. Systems are viewed as flexible and capable of facilitating multiple adaptive pathways for individuals and groups. Promoting social change also involves careful attention to critical analysis, values, language, and contextual processes. Examples are discussed throughout to illustrate how these principles have been used in the past and can be implemented in future efforts to promote social change.
Studying Liposomes by Tritium Bombardment
Authors: Kordyukova L.V. , Ksenofontov A.L. , Badun G.A. , Baratova L.A. , Shishkov A.V.
Published: December 2002

Bilayer liposomes from a mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylethanolamine (DPPC:DPPE=8:2, molar ratio) or DPPC labeled with 14C-DPPC (DPPC:14C-DPPC) were bombarded with thermally activated tritium atoms. The tritiated liposomes were hydrolyzed by phospholipase C, and the tritium incorporation into different parts of the bilayer along its thickness was determined. The tritium flux attenuation coefficients were calculated for the headgroup (k1=0.176±0.032 Å−1) and acylglycerol residue (k2=0.046±0.004 Å−1) layers indicating a preferential attenuation of the tritium flux in the headgroup region and relative transparence of the membrane hydrophobic part. The finding is potentially important to apply tritium bombardment for investigation of spatial organization of transmembrane proteins in their native lipid environment.
Dually Flat Manifolds and Global Information Geometry
Authors: Ay Nihat , Tuschmann Wilderich
Published: December 2002

Dually flat manifolds constitute fundamental mathematical objects of information geometry. This note establishes several results on the global properties and topology of dually flat manifolds which, in particular, provide answers to questions and problems in global information geometry posed by Amari and Amari-Nagaoka.
Valence basis sets for relativistic energy-consistent small-core actinide pseudopotentials
Authors: Cao Xiaoyan , Dolg Michael , Stoll Hermann
Published: December 2002

Gaussian (14s13p10d8f6g)/[6s6p5d4f3g] atomic natural orbital valence basis sets have been generated for relativistic energy-consistent small-core actinide pseudopotentials of the Stuttgart–Bonn variety. Effective valence spin–orbit operators supplementing the scalar-relativistic pseudopotentials have been derived from multiconfiguration Dirac–Hartree–Fock reference data. Pseudopotentials, basis sets and spin–orbit operators have been used to determine the first and second ionization potentials of all actinide elements at the multiconfiguration self-consistent field and multireference averaged coupled-pair functional level. Comparison is made to results obtained from large-scale calculations using uncontracted basis sets up to i-type functions and extrapolation to the basis set limit as well as to experimental data. Molecular calibration studies using the coupled-cluster singles, doubles, and perturbative triples approach are reported for the ground states of AcH, AcO, AcF, and ThO.
The fundamental photophysics of conjugated oligomer herringbone aggregates
Authors: Spano Frank C.
Published: December 2002

The photophysical properties of defect-free herringbone aggregates of π-conjugated oligomers are investigated theoretically using a two-particle basis set consisting of vibronic excitons and coupled vibronic–vibrational excitons. Incorporation of periodic boundary conditions allows the treatment of aggregates containing up to 1000 molecules. The vibrational distortion fields for the optically allowed excitons, including those responsible for the upper and lower Davydov components, are evaluated. The herringbone lattice supports both vibrationally dressed, heavy excitons as well as nearly free, light excitons. The former are responsible for the b-polarized absorption origin as well as two ac-polarized peaks slightly higher in energy. The strongly blueshifted main absorption peak is due to an exciton which travels with almost no nuclear distortion. The main absorption features are studied as a function of aggregate size and exciton bandwidth. The vibronic replicas in the aggregate emission spectrum are found to be strongly dependent on a destructive interference between one and two particle emissions. The primarily ac polarized replica intensities initially decrease with the number of molecules comprising the aggregate, N, converging to a nonzero value in the large N limit. By contrast, the b-polarized 0–0 line intensity increases linearly with N, eventually dominating the rest of the vibronic progression when N surpasses approximately 10. Beyond this size the aggregate radiative decay rate, γagg, scales linearly with N, eventually driving the quantum yield to unity when γagg surpasses the nonradiative decay rate. The relative magnitude of the 0–0 emission line versus the rest of the progression generally increases with increasing excitonic interactions. The sum of the (dimensionless) replica intensities diminishes from 1−exp(−λ2) in the weak excitonic coupling regime to approximately zero in the strong coupling regime. By contrast, the 0–0 line intensity scales as N throughout, increasing by a factor of exp(λ2) in going from the weak to strong excitonic coupling regimes.
Magnetoencephalography in ellipsoidal geometry
Authors: Dassios George , Kariotou Fotini
Published: December 2002

An exact analytic solution for the forward problem in the theory of biomagnetics of the human brain is known only for the (1D) case of a sphere and the (2D) case of a spheroid, where the excitation field is due to an electric dipole within the corresponding homogeneous conductor. In the present work the corresponding problem for the more realistic ellipsoidal brain model is solved and the leading quadrupole approximation for the exterior magnetic field is obtained in a form that exhibits the anisotropic character of the ellipsoidal geometry. The results are obtained in a straightforward manner through the evaluation of the interior electric potential and a subsequent calculation of the surface integral over the ellipsoid, using Lamé functions and ellipsoidal harmonics. The basic formulas are expressed in terms of the standard elliptic integrals that enter the expressions for the exterior Lamé functions. The laborious task of reducing the results to the spherical geometry is also included.
Towards vacuum superstring field theory: The supersliver
Authors: Mariño Marcos , Schiappa Ricardo
Published: December 2002

We extend some aspects of vacuum string field theory to superstring field theory in Berkovits’ formulation, and we study the star algebra in the fermionic matter sector. After clarifying the structure of the interaction vertex in the operator formalism of Gross and Jevicki, we provide an algebraic construction of the supersliver state in terms of infinite–dimensional matrices. This state is an idempotent string field and solves the matter part of the equation of motion of superstring field theory with a pure ghost BRST operator. We determine the spectrum of eigenvalues and eigenvectors of the infinite–dimensional matrices of Neumann coefficients in the fermionic matter sector. We then analyze coherent states based on the supersliver and use them in order to construct higher–rank projector solutions, as well as to construct closed subalgebras of the star algebra in the fermionic matter sector. Finally, we show that the geometric supersliver is a solution to the superstring field theory equations of motion, including the (super)ghost sector, with the canonical choice of vacuum BRST operator recently proposed by Gaiotto, Rastelli, Sen and Zwiebach.
An explanation of the sheath instability
Authors: Pandey B. P. , Roy Subrata
Published: December 2002

When the sheath accelerates in its plasma–bound motion as a result of the ion response to the electric field, one has a top-heavy equilibrium. In the sheath frame ions are accelerated towards the wall–sheath boundary. In such a situation sheath may become unstable. The sheath instability is examined as the Rayleigh–Taylor (RT) instability and RT growth rate is compared with the reported sheath instability in the literature.
Optical transitions and visible upconversion in Er3+ doped niobic tellurite glass
Authors: Lin Hai , Meredith Gerald , Jiang Shibin , Peng Xiang , Luo Tao , Peyghambarian Nasser , Pun Edwin Yue-Bun
Published: December 2002

Er 3+ doped Nb2O5–TeO2 (NT) glass suitable for developing optical fiber laser and amplifier has been fabricated and characterized. Intense and broad 1.53 μm infrared fluorescence and visible upconversion luminescence were observed under 975 nm diode laser and 798 nm laser excitation. For 1.53 μm emission band, the full width at half-maximum is 51 nm, the fluorescence lifetime is 2.6 ms, and the quantum efficiency is ∼100%. The maximum emission cross section is 8.52×10−21 cm2 at 1.532 μm, and is higher than the values in silicon and phosphate glasses. Under 798 nm excitation, efficient 531, 553, and 670 nm upconversion emissions are due to two-photon absorption processes. The “standardized” efficiency for the green upconversion light is 9.5×10−4, and this value is comparable to that reported for Er3+/Yb3+ codoped fluoride glasses. Intense visible upconversion fluorescence in Er3+ doped NT glass can be used in color display, undersea communication, and infrared sensor.
An exact fluid model for relativistic electron beams
Authors: Pennisi S.
Published: December 2002

An interesting and satisfactory fluid model has been proposed in the literature for the description of relativistic electron beams. It is obtained by imposing the entropy principle up to a certain order with respect to a smallness parameter ε measuring the dispersion of the velocity about the mean. Here the general exact solution is found, satisfying the entropy principle and the relativity principle up to whatever order.
Global numerical study of electron temperature gradient-driven turbulence and transport scaling
Authors: Labit B. , Ottaviani M.
Published: December 2002

A three-dimensional, electromagnetic, fluid code with flux boundaries conditions is used to study the scaling of electron thermal transport caused by electron temperature gradient-driven (ETG) turbulence. It is found that close to the ETG threshold, the thermal transport depends weakly on β, which differs from the heuristic formula χe∝1/β. It is shown also that electron thermal losses scale like gyro-Bohm. The observed electron temperature profiles appear more resilient than the ion temperature profiles obtained from previous ITG simulations in similar conditions.
Effect of iron doping on the properties of TbBaCo2O5.5 layered perovskite
Authors: Kopcewicz M. , Khalyavin D. D. , Troyanchuk I. O. , Szymczak H. , Szymczak R. , Logvinovich D. J. , Naumovich E. N.
Published: December 2002

The properties of the TbBa(Co2−xFex−)O5+δ (0<x⩽1) system, exhibiting the giant magnetoresistance effect, were studied by magnetization, thermogravimetric analysis (TGA), and resistivity measurements as well as by Mössbauer spectroscopy. It was found that the properties of this system dramatically change at x>0.1, at which a concentration-dependent orthorhombic–tetragonal transition takes place. The orthorhombic composition with x=0.1 exhibits a transition from an antiferromagnetic to weak ferromagnetic state at a temperature Ti=200 K on warming and at 160 K on cooling, and a transition from a weak ferromagnetic to paramagnetic state at TN=304 K. A metal–insulator transition occurs at TM=348 K on warming. Transformation into a tetragonal phase (x⩾0.12) leads to the disappearance of both the weak ferromagnetic state and the metal–insulator phase transition. Also, the Néel point drops. The orthorhombic and tetragonal phases coexist in the concentrational range (0.1<x<0.12). Mössbauer spectroscopy has shown that Fe3+ ions preferentially occupy two low-symmetry positions that are interpreted to be pyramidal sites with fivefold coordination. Both Mössbauer spectroscopy and TGA data revealed that the increase of Fe content leads to the decrease of oxygen content according to the formula TbBa(Co2−xFex)O5.5−x/2. It is supposed that at x⩾0.12 a change of the type of oxygen vacancy ordering occurs.
Conduction band offset in the AlxGayIn1−x−yP/Ga0.52In0.48P system as studied by luminescence spectroscopy
Authors: Vignaud D. , Mollot F.
Published: December 2002

The conduction band offset ΔEc between the lattice-matched, compressively, or tensilely strained AlxGayIn1−x−yP and Ga0.52In0.48P, grown on GaAs, has been measured by combined photoluminescence and photoluminescence excitation spectroscopy at 10 K. The goal was to study the composition of the quaternary barrier for which the maximum offset ΔEc is reached in such heterostructures. Within the limited set of barrier composition studied here, the optimum material for this purpose is the lattice-matched Al0.31Ga0.21In0.48P, for which ΔEc=210±15 meV. Comparison with calculations based on the model solid theory allows one to precisely measure the parameters involved in this model, although a precise determination of all the deformation potentials is out of reach with the limited set of results presented here. Nevertheless, estimations using this set of parameters suggest that strained AlxGayIn1−x−yP cannot improve the conduction offset compared to the strain-free material.
The Mn3+/2+ acceptor level in group III nitrides
Authors: Graf T. , Gjukic M. , Brandt M. S. , Stutzmann M. , Ambacher O.
Published: December 2002

Molecular-beam-epitaxy grown GaN:Mn and AlN:Mn layers with Mn concentrations around 1020 cm−3 were investigated by optical absorption and photoconductivity measurements. From electron spin resonance Mn is known to be mostly present in the neutral acceptor state in GaN without codoping. This leads to a reassignment of the optical absorption features to a charge transfer from the neutral Mn3+ oxidation state, either by direct photoionization at 1.8 eV or through a photothermal ionization process via an excited state at 1.42 eV above the Mn3+ ground state by spin-allowed Mn3+ 5E→5T internal absorption. The position of the Mn3+/2+ acceptor level at 1.8 eV above the valence-band edge of GaN makes the realization of carrier-mediated ferromagnetism rather unlikely in GaN:Mn.
Observation of orthogonally polarized transverse electric and transverse magnetic oscillation modes in a microcavity excited by localized two-photon absorption
Authors: Morrish Dru , Gan Xiaosong , Gu Min
Published: December 2002

We report on the observation of orthogonally polarized transverse electric (TE) and transverse magnetic (TM) oscillation modes in a microcavity excited by localized two-photon absorption. The polarization-dependent features of morphology-dependent resonance (MDR) effects in a microsphere under two-photon fluorescence excitation are quantitatively investigated. In addition to a clear separation of excitation and resonance wavelengths under two-photon excitation, the fluorescence emission can be tightly controlled in three-dimensional space within a microsphere. The experimental results demonstrate not only the orthogonal polarization nature of TE and TM oscillation modes but also the dependence of the strength and the polarization properties of MDR peaks on excitation locations in a microsphere.
Drift of domain walls of the ab type in weak ferromagnets
Authors: Gerasimchuk V. S. , Shitov A. A.
Published: December 2002

The drift motion of 180° domain walls of the ab type in a weak ferromagnet in an elastic stress field created by a sound wave propagating parallel or perpendicular to the plane of the domain wall is investigated. The dependence of the domain-wall drift velocity on the direction, amplitude, and polarization of the sound wave is found. The conditions for drift of a stripe domain structure are determined.
In-fiber nematic liquid crystal optical modulator based on in-plane switching with microsecond response time
Authors: Acharya Bharat R. , Baldwin K. W. , MacHarrie R. A. , Rogers John A. , Huang C. C. , Pindak R.
Published: December 2002

We describe a simple method and device design that enables fast in-plane electro-optic modulation in conventional nematic liquid crystal (NLC) devices. When combined with optimized NLC materials, this approach yields rotational speeds of 1°/μs (independent of rotation angle, over a wide range) at a moderately low voltage. The observed rotational dynamics indicate that even these high speeds may not represent fundamental physical limits. We demonstrate these ideas in a compact tunable NLC waveplate that uses microelectrodes patterned directly on the tips of optical fibers. These devices offer fast, continuously tunable optic axis with low insertion loss and good performance in the near infrared. Modulators that use this design have promising potential applications for polarization control and analysis in optical communication systems.
Synthesis of boron nitride nanofibers and measurement of their hydrogen uptake capacity
Authors: Ma Renzhi , Bando Yoshio , Sato Tadao , Golberg Dmitri , Zhu Hongwei , Xu Cailu , Wu Dehai
Published: December 2002

High-purity boron nitride (BN) nanofibers with diameters ranging from 30 to 100 nm were synthesized. Electron energy loss spectroscopy revealed that they have stoichiometric BN composition. The hydrogen uptake capacity measurements showed that the fibers could adsorb 2.9 wt % hydrogen under ∼10 MPa at room temperature. This hydrogen uptake capacity was compared with those of BN multiwalled or bamboo-like nanotubes under the same experimental conditions. It was suggested that the unique morphology of nanofibers, namely open-ended BN edge layers on the exterior surface, might facilitate hydrogen adsorption.
Novel mutation in sonic hedgehog in non‐syndromic colobomatous microphthalmia
Authors: Schimmenti Lisa A. , de la Cruz June , Lewis Richard Alan , Karkera J.D. , Manligas Glenda S. , Roessler Erich , Muenke Maximilian
Published: December 2002

Ocular (uveoretinal) colobomas occur in one in 10,000 individuals and present a substantive cause of congenital poor vision. The genetic bases of most forms of uveoretinal coloboma are elusive; mutations in PAX2 are found in only a few cases of coloboma of the retina and optic nerve that occur with renal anomalies as part of the renal‐coloboma syndrome (MIM#120330; #167409). From experimental data that upstream expression of sonic hedgehog (SHH) controls Pax2 expression in mice and zebrafish, and from clinical experience that colobomas are observed frequently in patients with holoprosencephaly, we hypothesized that SHH could be a candidate for non‐syndromic ocular colobomas (NSOC). We identified a three‐generation family in which both a proband and his mother presented with iris and uveoretinal colobomas without optic nerve involvement. A novel 24 bp deletion in the gene SHH was identified in these affected family members, and cosegregated with the phenotype. This is the first report of the association of SHH mutations and uveoretinal coloboma. © 2002 Wiley‐Liss, Inc.
Muellerian aplasia associated with ring chromosome 8p12q12 mosaicism
Authors: Loeffler Judith , Soelder Elisabeth , Erdel Martin , Utermann Barbara , Janecke Andreas , Duba Hans‐Christoph , Utermann Gerd
Published: December 2002

We report on a woman with Muellerian aplasia, renal and skeletal anomalies, and minor dysmorphic signs. Conventional cytogenetic analysis revealed mosaicism for a small supernumerary, undefinable ring chromosome. Chromosome microdissection and reverse painting demonstrated that this marker contained pericentric material from chromosome 8 (8p12q12). Thus, we identified a Muellerian aplasia phenotype with partial trisomy 8 mosaicism. © 2002 Wiley‐Liss, Inc.
Statistical morphological analysis of hippocampal principal neurons indicates cell‐specific repulsion of dendrites from their own cell
Authors: Samsonovich Alexei V. , Ascoli Giorgio A.
Published: December 2002

Traditionally, the sources of guidance cues for dendritic outgrowth are mainly associated with external bodies (A) rather than with the same neuron from which dendrites originate (B). To quantify the relationship between factors A and B as determinants of the adult dendritic shape, the morphology of 83 intracellularly characterized, stained, completely reconstructed, and digitized principal neurons of the rat hippocampus was statistically analyzed using Bayesian optimization. It was found that the dominant directional preference (tropism) manifested in dendritic turns is to grow away from the soma rather than toward the incoming fibers or in any other fixed direction; therefore, B is predominant. Results are robust and consistent for all examined morphological classes (dentate gyrus granule cells, basal and apical trees of CA3 and CA1 pyramidal cells). In addition, computer remodeling of neurons based on the measured parameters produced virtual structures consistent with real morphologies, as confirmed by measurement of several global emergent parameters. Thus, the simple description of dendritic shape based on dendrites' tendency to grow straight, away from their own soma, and with additional random deflections, proves remarkably accurate and complete. Although based on adult neurons, these results suggest that dendritic guidance during development may be associated primarily with the host cell. This possibility challenges the traditional concept of dendritic guidance: in that hippocampal cells are densely packed and have highly overlapping dendritic fields, the somatodendritic repulsion must be cell specific. Plausible mechanisms involving extracellular effects of spikes are discussed, together with feasible experimental tests and predicted results. © 2002 Wiley‐Liss, Inc.
Cleavage of eIF4G by HIV‐1 protease: effects on translation
Authors: Perales Celia , Carrasco Luis , Ventoso Iván
Published: December 2002

We have recently reported that HIV‐1 protease (PR) cleaves the initiation factor of translation eIF4GI [Ventoso et al., Proc. Natl. Acad. Sci. USA 98 (2001) 12966–12971]. Here, we analyze the proteolytic activity of HIV‐1 PR on eIF4GI and eIF4GII and its implications for the translation of mRNAs. HIV‐1 PR efficiently cleaves eIF4GI, but not eIF4GII, in cell‐free systems as well as in transfected mammalian cells. This specific proteolytic activity of the retroviral protease on eIF4GI was more selective than that observed with poliovirus 2Apro. Despite the presence of an intact endogenous eIF4GII, cleavage of eIF4GI by HIV‐1 PR was sufficient to impair drastically the translation of capped and uncapped mRNAs. In contrast, poliovirus IRES‐driven translation was unaffected or even enhanced by HIV‐1 PR after cleavage of eIF4GI. Further support for these in vitro results has been provided by the expression of HIV‐1 PR in COS cells from a Gag‐PR precursor. Our present findings suggest that eIF4GI intactness is necessary to maintain cap‐dependent translation, not only in cell‐free systems but also in mammalian cells.
Different heat shock protein 60 species share pro‐inflammatory activity but not binding sites on macrophages
Authors: Habich Christiane , Kempe Karina , van der Zee Ruurd , Burkart Volker , Kolb Hubert
Published: December 2002

In a study of seven different hsp60 species, we found that all mammalian and microbial proteins shared the property of eliciting an inflammatory response in mouse macrophages. In all cases, TNFα production was induced by 0.1 μM concentrations of hsp60. However, the different hsp60 preparations did not compete for the same binding site. The binding of fluorescence‐labeled human hsp60 was inhibited by excess unlabeled human, rat or mouse hsp60, but not hamster, Escherichia coli, Chlamydia pneumoniae or Mycobacterium bovis hsp60. We conclude that phylogenetically separate hsp60 species interact with innate immune cells via different recognition pathways.
Outcome of tyrosinaemia type III
Authors: Ellaway C. J. , Holme E. , Standing S. , Preece M. A. , Green A. , Ploechl E. , Ugarte M. , Trefz F. K. , Leonard J. V.
Published: December 2002

Tyrosinaemia type III is a rare disorder caused by a deficiency of 4‐hydroxyphenylpyruvate dioxygenase, the second enzyme in the catabolic pathway of tyrosine. The majority of the nine previously reported patients have presented with neurological symptoms after the neonatal period, while others detected by neonatal screening have been asymptomatic. All have had normal liver and renal function and none has skin or eye abnormalities. A further four patients with tyrosinaemia type III are described. It is not clear whether a strict low tyrosine diet alters the natural history of tyrosinaemia type III, although there remains a suspicion that treatment may be important, at least in infancy.
Hyperinsulinaemic hypoglycaemia—Leading symptom in a patient with congenital disorder of glycosylation Ia (phosphomannomutase deficiency)
Authors: Böhles H. , Sewell A. C. , Gebhardt B. , Reinecke‐Lüthge A. , Klöppel G. , Marquardt T.
Published: December 2002

A male infant is described who presented with persistent hyperinsulinaemic hypoglycaemia, responding to diazoxide treatment. However, this therapy was discontinued because of seizures as a consequence of disturbed water and electrolyte balance. Glucose homeostasis could only be maintained by subtotal pancreatectomy, which was performed at 3 years of age. He developed a severe thrombosis, whereon a congenital disorder of glycosylation (CDG) was suspected. An abnormal transferrin isoelectric focusing pattern was found and the diagnosis of CDG Ia was confirmed by enzyme and molecular genetic analysis. This is the first patient with phosphomannomutase deficiency (McKusick 601785) described presenting with severe hyperinsulinaemic hypoglycaemia.
Impact of new mutations in the methylenetetrahydrofolate reductase gene assessed on biochemical phenotypes: A familial study
Authors: Tonetti C. , Amiel J. , Munnich A. , Zittoun J.
Published: December 2002

Methylenetetrahydrofolate reductase (MTHFR) deficiency was identified in two out of four children born from nonconsanguineous parents. One of the affected children exhibited some clinical findings suggesting cystathionine β‐synthase deficiency; MTHFR activity was extremely reduced. In addition, hyperhomocysteinaemia, hypomethioninaemia, low total folate, especially methylfolate in red blood cells, and a reduced methylfolate/total folate ratio were found. Two mutations not yet reported, one on exon 1 of the gene changing an arginine to stop codon and one other on exon 9 changing an arginine to tryptophan were identified in both children in the compound heterozygous state associated with a common polymorphism, 1298A'C, also in the heterozygous state. The mother, homozygous for the mutation on exon 9 and for the polymorphism 1298A'C on exon 7, was clinically and biochemically normal, with normal folate status, mainly methylfolate levels in red blood cells, although MTHFR activity was moderately decreased. The father, heterozygous for the transition arginine to stop codon and for the common polymorphism 677C'T on exon 4, exhibited major biochemical abnormalities, hyperhomocysteinaemia and low methylfolate levels in red blood cells, but was clinically normal. The unaffected children had a biochemical pattern close to that of their mother and were heterozygous for the mutation on exon 9 and also for the two common polymorphisms, 677C'T and 1298A'C.

In the affected children, some biochemical abnormalities, including folate status, especially methylfolate levels, were improved with treatment combining methyltetrahydrofolic acid, hydroxocobalamin, pyridoxine and betaine; however, homocysteine concentrations remained high and methionine concentrations were lowered. The father was treated with folic acid, which partially improved biochemical abnormalities. The impact of these mutations is discussed.
Continuous glucose monitoring in children with glycogen storage disease type I
Authors: Hershkovitz E. , Rachmel A. , Ben‐Zaken H. , Phillip M.
Published: December 2002

Glycogen storage disease type I (GSD I) is characterized by impaired production of glucose from glycogenolysis and gluconeogenesis resulting in severe fasting hypoglycaemia. The aim of the present study was to examine the efficacy of a continuous subcutaneous glucose monitoring system (CGMS MiniMed), to determine the magnitude and significance of hypoglycaemia in GSD I and to evaluate the efficacy of its dietary treatment. Four children with GSD I were studied over a 72‐h period. Results indicated that the values recorded with continuous subcutaneous glucose monitoring were highly correlated with paired blood glucose values measured by glucometer. Significant periods of asymptomatic hypoglycaemia were noted, especially during night‐time. The study suggests that repeated continuous subcutaneous glucose monitoring may serve as a useful tool for the assessment of the long‐term management of GSD I patients.
The Test of Time: Predictors and Effects of Duration in Youth Mentoring Relationships
Authors: Grossman Jean B. , Rhodes Jean E.
Published: December 2002

The effects and predictors of duration in youth mentor relationships were examined. The study included 1,138 young, urban adolescents (Mean age = 12.25”, all of whom applied to Big Brothers Big Sisters programs. The adolescents were randomly assigned to either the treatment or control group, and administered questions at baseline and 18 months later. Adolescents in relationships that lasted a year or longer reported the largest number of improvements, with progressively fewer effects emerging among youth who were in relationships that terminated earlier. Adolescents who were in relationships that terminated within a very short period of time reported decrements in several indicators of functioning. Older adolescents, as well as those who had been referred for services or had sustained emotional, sexual or physical abuse, were most likely to be in early terminating relationships, as were married volunteers aged 26–30 and those with lower incomes. Several dyadic factors were also found to be related to earlier terminations, including race, gender, and relationship quality.
Progesterone Inhibits Insulin Secretion by a Membrane Delimited, Non-genomic Action
Authors: Straub Susanne G. , Sharp Geoffrey W. G. , Meglasson Martin D. , De Souza Christopher J.
Published: December 2002

In rat islets, progesterone caused a prompt concentration-dependent inhibition of glucose-stimulated insulin release with an IC50 of 10 μM at 8.4 mM glucose. The inhibition was specific since both testosterone and 17β-estradiol had no such effect. The degree of inhibition was similar in islets from male and female rats. The inhibition was not blocked in PTX-treated islets thus ruling out the Gi/Go proteins as mediators of the inhibition. Progesterone inhibited both glucose- and BayK-8644-stimulated insulin secretion in HIT-T15 cells and the IC50 vs. 10 mM glucose was also 10 μM. There was no effect on intracellular cyclic AMP concentration in the presence 0.2 and 10 mM glucose. Progesterone decreased [Ca2+]i under all conditions tested. The decrease in [Ca2+]i was due to blockade of the L-type voltage-dependent Ca2+ channels. Under Ca2+-free conditions, progesterone did not inhibit the stimulation of insulin release due to the combination of glucose, phorbol ester and forskolin. Thus blockade of Ca2+ entry appears to be the sole mechanism by which progesterone inhibits insulin release. As progesterone covalently linked to albumin had a similar inhibitory effect as progesterone itself, it is concluded that the steroid acts at the outer surface of the β-cell plasma membrane. These effects would be classified as either AI or AIIb in the Mannheim classification of nongenomically initiated steroid actions.
Anger and combat‐related posttraumatic stress disorder
Authors: Novaco Raymond W. , Chemtob Claude M.
Published: December 2002

We examined whether combat‐related PTSD was differentially associated with particular dimensions of anger on two multi‐index, psychometric instruments and whether the proportion of variation in PTSD scores explained by anger was significantly greater than that by demographic and exposure variables. We also examined the reliability and validity of a subset of Mississippi Scale items as an anger measure. Participants were 143 Vietnam combat veterans. Anger accounted for over 40% of the variance in Mississippi PTSD scores (minus the anger items) above that associated with age, education, and combat exposure. Veterans with structured‐interview–diagnosed PTSD were significantly differentiated from those without PTSD on all anger indices. The results point to anger treatment as a high priority for combat‐related PTSD.
Glu274Lys/Gly309Arg Mutation of the Tissue‐Nonspecific Alkaline Phosphatase Gene in Neonatal Hypophosphatasia Associated with Convulsions
Authors: Litmanovitz I. , Reish O. , Dolfin T. , Arnon S. , Regev R. , Grinshpan G. , Yamazaki M. , Ozono K.
Published: December 2002

We describe a patient diagnosed with lethal perinatal hypophosphatasia with a unique clinical presentation of convulsions that responded to vitamin B6. Genomic DNA sequence analysis of the tissue‐nonspecific alkaline phosphatase (TNSALP) gene revealed two missense mutations: a G‐to‐A transition resulting in a Glu to Lys at codon 274 (E274K), and a G‐to‐C transversion resulting in a Gly to Arg at codon 309 (G309R). The first mutation was maternally transmitted and was previously characterized as a moderate one, whereas the latter was paternally transmitted and has not been previously reported. Phenotype/genotype correlation indicates that G309R is a deleterious mutation that can lead to seizures and a lethal outcome, as was demonstrated in our patient.