bluuebunny/crossref_metadata_2025 huggingface dataset:
75As spin-lattice relaxation and resonance in KH2AsO4 type ferroelectric crystals
Authors: Blinc R. , Mali M. , Pirš J. , Žumer S.
Published: February 2004

The temperature dependence of the 75As dipolar spin-lattice relaxation time in both para- and ferroelectric KH2AsO4 and CsH2AsO4 has been determined and the results are related to the microscopic model of the phase transition. The temperature dependences of 75As NQR frequency and linewidth in KD2AsO4 and CsD2AsO4 and the corresponding Rb salts have been as well studied and a good agreement has been found between the theoretical and experimental results.
ESR and electronic spectral investigation of the self-association of phthalocyanine dyes in solution
Authors: Abkowitz Martin , Monahan Alan R.
Published: February 2004

The degree of molecular association of a copper phthalocyanine dye in benzene and tetrahydrofuran has been studied by electronic spectroscopy and ESR. Electronic spectroscopy in the visible spectral region demonstrates the existence of monomer-dimer equilibria in the 10−6–10−3 M concentration range. The dimerization constants Keq=Cd/Cm2 are (1.58± 0.09)× 104M−1 and (1.41± 0.50)× 102M−1 at room temperature in benzene and tetrahydrofuran, respectively. The ESR envelope spectra are found to vary systematically in the same concentration range as a function of solvent at fixed temperature. To deduce the manner in which aggregation in these solvents influences the detailed features of the ESR envelope spectrum, it is found useful to follow the evolution of envelope lineshape in copper phthalocyanine-metal-free phthalocyanine solid solutions as the concentration of copper phthalocyanine is progressively increased. The principal effect is found to be the perturbing influence of intermolecular copper exchange interactions in averaging local hyperfine fields, a process which can be both computer simulated and followed directly in the experimental spectra.
Direct determination of temperature dependence of refractive index of liquids
Authors: Olson James D. , Horne Frederick H.
Published: February 2004

A new, direct method for determination of the temperature dependence of refractive index has been developed. It consists of an interferometric examination of a liquid in which a temperature gradient is established and maintained. The experiments reported were performed with a Bryngdahl wavefront shearing interferometer [J. Opt. Soc. Am. 53, 571 (1963)] and a He–Ne laser light source. Results for (∂ n/∂ T)p/10−4 °K−1 at 1 atm, 298.15°K, and 632.8 nm are: H2O, −0.989; CCl4, −5.70; C6H12, −5.38; and C6H6, −6.21; with an overall experimental standard deviation of about 1%. Effective molecular radii and polarizabilities of these liquids are calculated from the Böttcher equation.
Role of small polarons in the metal-insulator transition
Authors: Chaikin P. M. , Garito A. F. , Heeger A. J.
Published: February 2004

An analysis of the effects of small polaron formation on the metal-insulator transition as expressed in terms of the Hubbard model is presented. The system dealt with contains an electronic subsystem and a rigid lattice of polarizable molecules. The electron-excitation coupling is treated by a canonical transformation that leads to reduced Hubbard constants for both the Coulomb interaction and the bandwidth. Polaron formation leads in addition to the creation of a polarization bond in the crystal. This contribution to the total cohesive energy of the solid is shown to be equal in magnitude to the polaron binding energy. The effective antiferromagnetic exchange interaction (via virtual charge transfer) is calculated for both excitonic and phononic polarons. A discussion of the effect of increased polarizability is presented with emphasis on the possibility of stabilizing the metallic phase at low temperatures in real crystals.
Line shape and intensity considerations in microwave optical magnetic resonance induced by electrons and related experiments
Authors: Miller Terry A.
Published: February 2004

A density matrix approach to the phenomena of molecular level crossing, level anticrossing, and double resonance experiments is formulated. A general equation for the time evolution of the density matrix has been obtained, which can be used to described the above behavior in a multilevel system. The equations appropriate to a MOMRIE (Microwave Optical Magnetic Resonance Induced by Electrons) experiment are solved explicitly in the two-level approximation. The applicability of this approximation to the MOMRIE experiments on the H2 molecule is quantitatively examined, analytically and by computer simulation. Predictions of the theory are compared with observed lineshapes, relative and absolute intensities, and linewidths obtained from MOMRIE experiments.
Temperature dependence of the nuclear quadrupole resonance frequencies in solids and the external modes approximation for lattice dynamics
Authors: Silva Paulo R. P.
Published: February 2004

A discussion is presented on the various terms that may contribute to the temperature dependence of the NQR frequencies in molecular solids. It is shown that the external modes approximation in lattice dynamics is particularly suited to describe these effects in NQR spectroscopy. Two cases may be considered. Case (1): The quadrupole nucleus belongs to a nearly rigid cluster of atoms here called a unit. Case (2): The quadrupole nucleus may be considered as a single atom, not belonging to a complex unit. In this paper only Case (1) will be considered; Case (2) will be discussed elsewhere. It is shown that the separation of variables obtained from the external modes approximation allows a maximum economy of coordinates and conveniently permits a most direct connection with results from microwave experiments. Explicit expressions are obtained for q and η in terms of the librations and internal vibrations of the cluster of atoms that are assumed to surround the quadrupole nucleus. Crossed librational-vibrational averages of type 〈 uxruλv〉 are shown to affect the NQR frequencies in a first approximation, both for η0 ≠ 0 and η0=0. Crossed averages, usually neglected without justification, can be shown to be present whenever the two coordinates involved are modulated at the same frequencies. The translational modes can be shown to produce a first-order Doppler effect which causes no frequency shift, but instead causes a small broadening of the resonance line.
Triplet energy transfer in polyadenylic acid: Temperature dependence of phosphorescence quenching by Mn2+
Authors: Szerenyi P. , Dearman H. H.
Published: February 2004

The quenching of poly rA phosphorescence by Mn2+ is investigated in the temperature range from 4.2 to 77°K. At 4.2°K the phosphorescence intensity is found to decrease linearly whereas at 77°K it decreases nearly logarithmically with increasing quencher concentration. The decay of phosphorescence at 4.2°K is strictly exponential with lifetime, τe, of 2.82 sec independent of quencher concentration. At higher temperatures and nonzero quencher concentrations the decays are nonexponential with relatively fast initial decays. The phosphorescence is thought to arise from triplet traps that are formed when an ordered sequence of monomers is interrupted by some other stereochemically allowed conformation of the monomer. The above observations are interpreted in terms of a one dimensional random walk of the triplet excitation over the trap sites. The limiting, thermally activated jump time of triplet excitation from a trap to a nearest neighbor is found to be 7× 10−3 sec. From the temperature dependence of this jump time the trap depth is calculated to be 115 cm−1. An upper bound to the average length of ordered sections in poly rA in this temperature range is found to be 7 monomer units. The phosphorescence spectra and decays of several adenine containing subunits of poly rA in various environments at 77°K are reported. Evidence is presented for intramolecular hydrogen bonding in single stranded poly rA and is suggested to account for the differences in phosphorescence spectra and decays of the former and of poly dA.
Molecular beam measurements of total collision cross sections of H2O
Authors: Snow W. R. , Dowell J. T. , Chevrenak J. G. , Berek H. E.
Published: February 2004

The total cross section for H2O–H2O scattering is measured with a supersonic nozzle beam system. The primary beam has a narrow velocity distribution, and the velocity is varied by control of the nozzle temperature. Velocities are determined by time-of-flight techniques. Cross sections obtained are averages over a Maxwellian distribution of the target molecules. Data at three velocities are presented. The cross sections for H2O are surprisingly small, for example, 3.07× 10−14 cm2 at 1× 105 cm/sec, indicating little contribution from the dipole-dipole interaction.
Heat of dissociation of As4(g) and the heat of formation of As2(g)
Authors: Murray J. J. , Pupp C. , Pottie R. F.
Published: February 2004

The equilibrium As4(g)=2As2(g) has been studied in detail over solid phase MoAs2 and Mo2As3 using the Knudsen effusion technique combined with a mass spectrometer. A ``see-through'' ion source and a liquid-nitrogen cooled condensation plate were used to eliminate the spurious As4(g) which has been encountered by other investigators. Excellent agreement was obtained between the second- and third-law enthalpies. From equilibrium constants measured between 807 and 1050°K, the following third-law heats were determined: As4(g)=2As2(g), Δ H0°=53.95± 1.1, Δ H298°=54.26± 0.7, Δ H0°(f)[As2(g)]=45.65± 0.7, Δ H298(f)°[As2(g)]=45.45± 0.7, all in kilocalorie mole−1, the errors being estimates of total error. The results obtained when GaAs, Mo5As4, and Zn3As2 were used as source phases are briefly described. The results of previous investigations of the As4(g)=2As2(g) equilibrium are critically discussed.
14N nuclear quadrupole resonance in compounds containing N–N bonds. IV. Nitrosamines
Authors: Sauer Enrique G. , Oja Tõnis
Published: February 2004

The complete nitrogen-14 nuclear quadrupole resonance spectra of six nitrosamines at 77°K have been determined with cw and pulsed techniques. Absorption lines belonging to the amino nitrogen atom lie at rather low frequencies and are virtually undetectable with cw techniques. The low frequencies of the amino lines indicates a considerable loss of π charge to the oxygen atom. As a result of this charge transfer, the polarity of the N=O bond is smaller than the polarity of a N–OH bond. The N–N bond was found to be slightly polarized toward the amino nitrogen atom, the charge unbalance of this bond amounts to about 0.08 electrons.
Thermodynamic properties of oxalyl fluoride from 13°K to its boiling point
Authors: Pace E. L. , Hodge P. E.
Published: February 2004

The saturated molar heat capacity has been measured from 13°K to its normal boiling point, 270.13°K, for a sample of 99.94 mole% purity. The molar heat of fusion was found to be 3204 cal/mole at the triple-point temperature of 260.73°K. The molar heat of vaporization at the normal boiling point was found to be 6753 cal/mole. The vapor pressure of the solid in the range from 234°K to the triple point of 260.73°K is represented by the equation lnP(torr)=115.38986 − 8720.5964/T − 13.623524 lnT. The vapor pressure of the liquid from the triple point to the boiling point of 270.13°K is represented by the equation lnP(torr)=185.93601 − 10 317.218/T − 25.202996 lnT. The standard entropy of oxalyl fluoride gas at the normal boiling point was found to be 73.01± 0.16 cal/mole·° K. Neither of the two fundamental frequency assignments reported in the literature when used in the statistical entropy calculation gives satisfactory agreement with the calorimetric entropy. It is believed that the discrepancy results from the uncertainty in the assignment of one or more of the low frequency Raman-active modes of the molecule.
Eigenfunctions and eigenvalues of the Thomas-Fermi density matrix. The simple harmonic oscillator
Authors: Handler George S. , Benton Virginia L.
Published: February 2004

The eigenfunctions and eigenvalues of a Hermitian Thomas-Fermi density matrix for the one-dimensional harmonic oscillator are examined in detail. The major defect of Thomas-Fermi theory is shown to be the departure of the density matrix from N representability. The imposition of indempotency leads to greatly improved particle densities, including very well developed density oscillations.
V
→
T
,R and V→V relaxation in DCl systems
Authors: Zittel Paul F. , Moore C. Bradley
Published: February 2004

A laser-fluorescence technique was used to measure the V→T,R relaxation of DCl (ν = 1) by DCl, rare gases, and hydrogen isotopes, as well as the V→V relaxation of HCl, DCl, and CO by deuterium halides, first-row diatomics, and some polyatomic molecules. The dependence of V→V probabilities on energy discrepancy qualitatively indicates the role of rotation in removing excess vibrational energy. Significant differences in the interaction potential between HX and various first-row diatomics is also suggested. HCl→ 16O2 and O182 V→ V relaxation was measured and leads to an estimated probability for the multiquantum process, HCl(ν=1)+ 18O2(ν=0)→ HCl(ν=0)+ 18O2 (ν=2)+Δ E=−30 cm−1.
Spinodal decomposition in the tetragonal system
Authors: Wu Kung-Tung , Mendelson Kenneth S.
Published: February 2004

The method of Cahn has been used to study spinodal decomposition in systems with tetragonal symmetry. The gradient energy and diffusion mobility in tetragonal systems have been considered in addition to the elastic free energy, previously treated by Stubican, Schultz, and Bitler. The results have been applied to the system TiO2–SnO2. In this system the theory predicts that spinodal decomposition will take place along the [001] direction, the additional anisotropies considered in this paper reinforcing the effects treated by Stubican, Schultz, and Bitler.
Zeeman effect of Cl35 NQR in 2,4-α-α-α- pentachlorotoluene and p-chloroaniline
Authors: Sasikala D. , Murty C. R. K.
Published: February 2004

Zeeman effect studies of Cl35 nuclear quadrupole resonance have been carried out at room temperature in single crystals of 2,4-α-α-α- pentachlorotoluene and p-chloroaniline. Two field gradients have been found in the crystal 2,4-α-α-α- pentachlorotoluene, one for each chlorine in the 2 and 4 positions. The crystal class is identified as monoclinic. The orientation of the principal axes has been found with respect to the crystallographic axes. The asymmetry parameter cell, and the C–Cl bond characters are estimated. Two inequivalent field gradients have been found in the crystal p-chloroaniline. The two z axes of the field gradients lie in the ab plane. A comparison of the present results with Meal's data and x-ray data has been made. It was also found that there is a possibility of different growth habit for the cylindrical crystals in p-chloroaniline and 2,4-α-α-α- pentachlorotoluene.
Velocity of ultrasound in potassium-ammonia solutions: Dilute solutions
Authors: Bowen D. E. , Parker M. H. , Franceware L. B.
Published: February 2004

New data on the velocity of 10 MHz compressional waves in dulute solutions of potassium in liquid ammonia are presented. These data are not consistent with the existence of the reported volume expansion minimum. Comparison of this data with earlier data on more concentrated solutions shows that the concentration dependence of the sound velocity is quite similar to that exhibited by both the density and viscosity and is consistent with a model of the solutions proposed by Cohen and Thompson.
ESR study of F32− in γ-irradiated KAsF6
Authors: Subramanian S. , Rogers Max T.
Published: February 2004

An ESR study of single crystals of KAsF6, γ irradiated and observed at 77°K, has been made. A three-fluorine center similar to the Vt center, F32−, has been identified, and the principal components and directions for the g tensor, and for the fluorine hyperfine interaction tensors, have been obtained. The center is nonlinear with bond angle F–F–F = 150° ± 3°, the odd-electron density being larger on the central fluorine atom and smaller on the two equivalent end fluorine atoms of the radical. INDO calculations suggest that it is a σ-type radical with the unpaired spin density distributed in the fluorine orbitals lying in the plane of the three atoms.
Molecular orbital theory of the hydrogen bond. IV. The dimers ROH···OCH2
Authors: Del Bene Janet E.
Published: February 2004

Ab initio LCAO-MO-SCF calculations with a minimal STO-3G basis set have been performed to determine the structures and energies of the dimers ROH···OCH2, where R may be H, or one of the isoelectronic substituents CH3, NH2, OH, or F. It is found that the order of hydrogen bond energies in the series parallels the order of sigma electron withdrawing ability of the substituent. Proton-lone pair, dipole-dipole, and long range interactions are discussed as factors which stabilize hydrogen bonded dimers. The structures of the dimers are analyzed in terms of a general hybridization model for the hydrogen bond.
Spectroscopic properties of polyenes. I. The lowest energy allowed singlet-singlet transition for cis- and trans- 1,3,5-hexatriene
Authors: Gavin R. M. , Risemberg Salomon , Rice Stuart A.
Published: February 2004

The absorption spectra of cis- and trans- 1,3,5-hexatriene are reported for the region of the first allowed singlet-singlet electronic transition, 2600 to 2100 A. A least-squares procedure in which a Lorentzian line shape is assumed for each band was used to fit the spectra. Progressions are found of 408, 1262, and 1626 cm−1 for the cis isomer and of 350, 1232, and 1628 cm−1 for the trans isomer. The 0–0 transition for the cis compound, 39668 cm−1, lies about 130 cm−1 lower than that for the trans, 39800 cm−1. The fact that the 0–0 transition energy for cis is less than that for trans is interpreted as evidence that the cis isomer has a non-planar geometry in the electronic ground state. The extinction coefficient for the 0–0 band of the trans isomer is about 1.5 times that for the cis.
Negative ion reactions in N2O at low energies
Authors: Marx R. , Mauclaire G. , Fehsenfeld F. C. , Dunkin D. B. , Ferguson E. E.
Published: February 2004

The reaction of O− with N2O has been studied as a function of temperature and O− kinetic energy using ion cyclotron resonance and flowing afterglow techniques. The reaction has a measured rate constant at room temperature of 2.2± 0.4 cm3/sec in the flowing afterglow and 2.5± 0.5 × 10−10cm3/sec in the ICR. As the O− energy is increased the rate constant declines. Over the entire range of energies NO− is the only observed reaction product. Energy exchange between O− and N2O and Ar have also been studied as well as reactions involving the NO− product of the O− reaction with N2O. The present results are compared with previous results.
Electron-electron double resonance study of trapped electrons in 10M NaOH alkaline ice glass
Authors: Yoshida Hiroshi , Feng Da-Fei , Kevan Larry
Published: February 2004

Electron-electron double resonance (ELDOR) has been used to test the validity of the noninteracting spin-packet model for inhomogeneously broadened electron paramagnetic resonance (EPR) lines as applied to trapped electrons in 10M NaOH ice. Spectral simulation of field-swept ELDOR spectra based on the spin-packet model qualitatively, but not quantitatively, accounts for the observed spectra. The quantitative failure of the spin-packet model is interpreted in terms of spin diffusion within the EPR line. Structure in frequency-swept ELDOR spectra, which is not predicted by the spin-packet model, has been observed and interpreted as ∼ 5.7 G hyperfine coupling with eight matrix protons. This supports a tetrahedral model of oriented water dipoles for the immediate environment of the trapped electron in alkaline ice.
Optically detected gas phase magnetic resonance spectrum of the CN radical
Authors: Cook Thomas J. , Levy Donald H.
Published: February 2004

The microwave magnetic resonance spectrum of rotationally perturbed levels of the A 2Π3/2 and B2 Σ+ excited electronic states of the CN radical has been observed in the gas phase using optical detection. The theory of the Zeeman effect has been used to calculate the energy levels of the system as a function of applied magnetic field strength. The parameters appearing in the molecular Hamiltonian have been adjusted to produce agreement between the experimental and calculated spectrum, and this fitting procedure has provided measured values for the interelectronic state coupling parameters and certain other molecular constants. The values of these interelectronic coupling parameters between the ν = 0, B2 Σ+ state and the ν = 10, A 2Π state were determined to be <ν = 10 A 2Π|Lx|ν = 0B 2Σ+>= 0.0038, <ν = 10 A 2Π|ALx|ν = 0B 2Σ+>= −2602 MHz, <ν = 10 A 2Π|BLx|ν = 0B 2Σ+> 534 MHz. These values differ from those which were calculated using optical data.
On the calculation of heats of vaporization from hard sphere equations of state
Authors: Wilhelm Emmerich , Battino Rubin
Published: February 2004

The enthalpies of vaporization of 22 polyatomic substances have been calculated at 298.15°K by using hard sphere reference assemblies (SPT and CST, respectively) and values for the effective hard sphere diameters obtained via gas solubilities. Agreement between calculated and observed values is in general good, especially for nearly spherical molecules. In addition, the difference of the molar heat capacity between gas and liquid was calculated for several substances and compared to experimental results with very good agreement.
ESR and crystal-field anisotropy in 6S spin-state ions in solution
Authors: Burlamacchi L. , Romanelli M.
Published: February 2004

The nature of the disortion of the crystal-field symmetry acting on symmetrically coordinated Fe(III) and Mn(II) complexes is investigated. Fine splitting components in the spectra of viscous solutions and of frozen solutions denote the presence of a wide distribution of sites with different zero-field splitting terms, part of which are comparable to, or greater than, the Zeeman term. In low-viscous solutions the mean zero-field splitting term, which accounts for the linewidth of the ESR spectra, arises from the averaging of essentially the same crystal-field distribution.
Molecular beam electric resonance spectra of reaction products: Vibrational energy of LiF from Li + SF6
Authors: Mariella R. P. , Herschbach D. R. , Klemperer W.
Published: February 2004

Reactively scattered LiF from crossed molecular beams of Li and SF6 is analyzed by electric resonance spectroscopy. Stark transitions between the J = 1, MJ = 0 and J = 1, MJ = 1 rotational states are measured for the v = 0–3 vibrational levels. Intensity ratios for these levels correspond to a Boltzmann distribution. The vibrational temperature is Tv (LiF)=920±30°K with the parent beams at T(Li)∼ 900°K and T(SF6)=400°K; it increases appreciably with increase in T(Li) over a range of ∼ 150°K but is independent of T(SF6) over a range of 450°K. The magnitude of Tv (LiF) is only about half that corresponding to equipartition of energy in an LiSF6 complex. The observed refocusing properties of the LiF indicate its translational and rotational energy are also relatively low. Most of the approximately 60 kcal/mole reaction exoergicity thus goes into internal excitation of the SF5 radical (enough to allow dissociation to SF4+F). These results, together with previous data on the LiF cross section and angular distribution, indicate that the reaction does not proceed via a long-lived LiSF6 complex, in contrast to the analogous Cs+SF6 reaction. Vibrational relaxation was observable only for SF6 fluxes considerably higher than those used in the measurements. In another experiment, however, vibrational relaxation was measured for a thermal LiF beam (at 1100°K) scattered at an angle of 20° by the crossed SF6 beam (at ∼ 300°K). The vibrational temperature of the scattered LiF is markedly lowered (to ∼ 750°K). The dipole moment of 7Li19F is also determined for the v = 0–5 vibrational states.
Collision induced dissociation: A statistical theory
Authors: Rebick C. , Levine R. D.
Published: February 2004

A statistical theory of collision induced dissociation using the three body angular momentum introduced by Delves and Smith is presented. A distinction is made between direct dissociation (no two body intermediates) and indirect processes, due to the formation of quasibound diatoms (of either the chaperon or the energy transfer type). The post-threshold energy dependence in the statistical theory is of the type A(E−E0)n/Etr where E is the total energy and Etr the translational energy. (n ≈ 2 or 1.5 for direct and indirect processes.) The threshold energy, Eo, can be determined by a suitably linearized plot without a prior determination of n. Following a series of diagnostic calculations for the reaction He+H2+(ν)→ He+H++H, the experimental results are simulated via the introduction of a nonstatistical (i.e., selective) bias by representing the dependence of A on the initial vibrational energy in the form A ∝ exp(−λ fν) where fv is the fraction of enegy in the vibration.
Is zinc deficiency a risk factor for atherosclerosis?
Authors: Beattie John H. , Kwun In-Sook
Published: February 2004

The development of atherosclerosis is influenced by genetic, lifestyle and nutritional risk factors. Zn and metallothionein deficiency can enhance oxidative-stress-related signalling processes in endothelial cells, and since changes in available plasma Zn may affect the Zn status of the endothelium, Zn deficiency could be a risk factor for IHD. Although the association of Zn with many proteins is essential for their function, three key signalling processes are highlighted as being principal targets for the effect of Zn deficiency: the activation of NF-κB, the activation of caspase enzymes and the signalling of NO. The need to develop a reliable indicator of Zn status is critical to any epidemiological approach for studying the relationship between Zn status and disease incidence. Studies using appropriate animal models and investigating how the plasma Zn pool influences endothelial intracellular labile Zn would be helpful in appreciating the importance of Zn deficiency in atherogenesis.
Call centres for enhanced reference services: a comparison of selected library call centres and the Reference Point at National Library of Singapore
Authors: Sattar Chaudhry Abdus , Jeanne Chua
Published: February 2004

The concept of a call centre is defined and the technologies employed in call centre applications are examined. The principles and practices relevant in the context of telephone services offered by libraries are highlighted. Features of call centres in selected libraries are described and compared with the Reference Point at the National Library of Singapore and recommendations on call centre practices with regard to the provision of LIS are presented.
Synthesis and characterization of complex esters for motor and hydraulic oils
Authors: Pavlov D.J. , Gospodinova N.N. , Glavchev I.K.
Published: February 2004

The aim of this study is the synthesis and characterization of motor and hydraulic oils based on complex esters of dicarboxylic acids and polyol esters. The esters have been prepared by polyesterification of adipic or sebacic acids with polyethylene glycol and by subsequent reaction with 2‐ethylhexanol using a new high active catalyst tetraoktyltitanate (TOT)‐TlCl. The synthesis of pentaerythritol esters of monocarboxylic acids has also been undertaken in the presence of the same catalyst. The catalyst reduces the time and temperature required for the reaction to produce esters with characteristics of standard motor and hydraulic oils.
Dry friction and wear rates as under liquid lubrication of ceramic/carbon couples up to 450°C
Authors: Kleemann Jens , Woydt Mathias
Published: February 2004

In a high temperature tribometer, stationary carbon has been tested against different rotating ceramics (SiC, Si3N4, Al2O3, WC‐6Ni, MgO‐ZrO2, (Ti, Mo)(C, N)) and stainless steel (DIN 1.4876). The rotating discs were grinded, polished and/or lapped. For most material combinations, the wear morphology is known from available literature. A transfer film with a typical wear pattern was found on the rotating disc. The combination of antimony graphite EK3245 against MgO‐ZrO2 did not form carbonaceous transfer layer. Through advanced variation of the roughness up to Rpk=0.011 μm, the wear rate has been reduced to Kv ≈ 3.5×10−8 mm3/N m at a stable coefficient of friction in a “millirange” of μ∼0.008 for a sliding distance of 20.000 m.
Annoying, intrusive, … and constitutional: telemarketing and the national Do‐Not‐Call Registry
Authors: Galloway Chester S. , Brown Steven P.
Published: February 2004

The recent adoption by the US Federal Trade Commission of the national Do‐Not‐Call Registry prohibiting most telemarketers from contacting individuals once their number is added to the listing is a threat to the US domestic telemarketing industry. Analysis of US federal law suggests that the national registry is likely an unconstitutional exercise of administrative power. To be legal, governmental prior restraints on commercial speech must pass the four‐part Central Hudson test adopted by the US Supreme Court. The Do‐Not‐Call Registry fails parts three and four of the test and probably part two as well. There is an insufficient fit between the stated governmental purpose of the regulation and its operation. Moreover, balancing the benefits from the registry against the harm it inflicts further militates against its constitutionality. International and public relations implications are explored and discussed.
Building loyalty at Things Remembered
Authors: Mulhern Terry , Duffy Dennis
Published: February 2004

Customer loyalty programs have become increasingly popular in a variety of industries. Marketers use loyalty‐building strategies to help improve customer retention and boost share of customer. One of the industries in which loyalty programs have been used frequently is retailing. When a customer walks out the door of a retail establishment, the marketer can never be sure that the customer will ever come back. In this case study we will examine how Things Remembered, a national retailer, did all the right things to implement a successful loyalty program and how they avoided many of the mistakes that cause a program to fail.
Interleukin‐1β Stimulates Growth Hormone‐Releasing Hormone Receptor mRNA Expression in the Rat Hypothalamus In Vitro and In Vivo
Authors: Taishi P. , De A. , Alt J. , Gardi J. , Obal F. , Krueger J. M.
Published: February 2004

Changes in growth hormone‐releasing hormone (GHRH), GHRH‐receptor (R), somatostatin and interleukin (IL)‐1β mRNA levels were determined in fetal rat hypothalamic cultures after administration of IL‐1β (1, 10, 100 ng/ml, 2 h incubation), and in adult rat hypothalamus 5 h after intracerebroventricular injection of IL‐1β (2.5 and 25 ng). IL‐1β stimulated GHRH‐R mRNA expression both in vitro (10 and 100 ng/ml) and in vivo (2.5 and 25 ng). Somatostatin mRNA was significantly stimulated and GHRH mRNA slightly reduced in vitro, while these mRNA species were not altered in vivo in response to IL‐1β. IL‐1β stimulated its own expression both in vitro (10 and 100 ng/ml) and in vivo (25 ng). IL‐1β‐induced mRNA responses occurred 2 h after treatment in vitro (incubation times, 30 min to 6 h). IL‐1β also elicited slight GHRH releases in vitro. Up‐regulation of hypothalamic GHRH‐R by IL‐1β may explain previous findings suggesting that IL‐1β stimulates GHRH activity.
Activation of Postsynaptic GABAB Receptors Modulate the Firing Activity of Supraoptic Oxytocin and Vasopressin Neurones: Role of Calcium Channels
Authors: Li Y. , Stern J. E.
Published: February 2004

Oxytocin and vasopressin release from neurohypophysial terminals is closely related to the firing activity of magnocellular neurones in the supraoptic (SON) and paraventricular nuclei. It is well established that activation of GABAA receptors potently inhibits the activity of SON neurones and, thus, hormone release. However, whether postsynaptic GABAB receptors are expressed in magnocellular neurones, and the role they play in controlling their firing activity, is still controversial. In the present work, we combined immunohistochemical and electrophysiological techniques to determine whether activation of GABAB receptors in identified oxytocin and vasopressin neurones modulates their firing activity. Patch‐clamp recordings from SON neurones were obtained either in the slice preparation or from acutely dissociated neurones. Activation of GABAB receptors with the selective agonist baclofen (10 µm) inhibited voltage‐gated Ca2+ currents, reduced the duration of individual action potentials, as well as the magnitude of the hyperpolarizing after‐potential. SON firing activity was reduced by baclofen, and effect that was accompanied by a small membrane hyperpolarization. The inhibition of firing discharge persisted in the presence of synaptic blockade media, and was also observed in acutely dissociated SON neurones. Finally, GABAB‐mediated modulation of firing activity was largely blocked by the Ca2+ channel blocker Co2+ (2 mm). In general, baclofen modulatory actions were significantly larger, or observed more predominantly, in vasopressin neurones. In summary, these results support the expression of functional postsynaptic GABAB receptors in SON neurones, activation of which efficiently modulates neuronal excitability, in a Ca2+‐ and cell‐type dependent manner.
Definitions, periodization, and prospects for thelongue duree
Authors: Armstrong John A.
Published: February 2004

AbstractTwo related problems face the study of nations and nationalism. Primordialism, as the belief that nations have usually existed from time immemorial, has generally been discarded by scholars. However, perennialism, the belief that a few nations existed in antiquity or the Middle Ages, and revived subsequently, has more support, along with the concept that national self‐assertion generally becomes stronger at historical intervals. Probably more support has been given to the use of ethnie (as presented especially by Anthony D. Smith) a lengthy preparatory stage for the typical nation when its name, constitutive myth, historical memory, and territorial attachment are acquired. More research is needed on the chronological and geographical variations on these themes.
The timelessness of nations
Authors: Connor Walker
Published: February 2004

Abstract. Anthony Smith has criticized my conclusion that most of the peoples currently recognized as constituting nations acquired national consciousness only in the late nineteenth or early twentieth centuries. He traces our disagreement to fundamental differences concerning the essence of the nation. A comparison of our definitions confirms profound differences, and it is contended that Smith's definitions, by joining two quite dissimilar and often conflictual identities (civic and ethnic) preclude a dialogue concerning the nature and the history of ‘the nation’. A rejoinder to Smith's specific criticisms is followed by a restatement of the factors that make calculating when a given nation emerged so difficult. Finally, it is noted that the issue of when a nation came into being is not of key significance: while in factual/chronological history a nation may be of recent vintage, in the popular perception of its members, it is ‘eternal’, ‘beyond time’, ‘timeless’. And it is not facts but perceptions of facts that shape attitudes and behavior.
Anthony D. Smith on nations and national identity: a critical assessment
Authors: Guibernau Montserrat
Published: February 2004

This paper offers a critical assessment of Anthony D. Smith's classical definition of the nation. In so doing, it argues that Smith fails to establish a clear‐cut distinction between the concept of nation and state, since he attributes to the nation some of the features of the state, for instance the sharing of legal rights and duties among all its members. In addition, Smith's definition neglects the existence of nations without states. The paper offers a detailed examination of Smith's definition of the nation and the possible reasons why he has decided to introduce some fundamental changes into it in his most recent work. The paper then moves on to consider Smith's definition of national identity and to offer an alternative to it by including a reflection of how national identity is constructed in the global era.
Globalising national states
Authors: Tønnesson Stein
Published: February 2004

Abstract Globalisation has ambiguous effects on states. On the one hand, it favours national states since citizens' identification with their state provides for political and social stability. On the other hand, globalisation makes it difficult for states to be national because the scope of sovereign decision‐making is reduced, and many citizens prioritise trans‐national networks over national ones. Hence well‐established national states, which are sufficiently resilient to maintain a national culture while also engaging with the wider world, enjoy a comparative advantage over such states who either fail to maintain national cohesion or seek to protect it by rejecting foreign influence. The present article revisits the most common typologies of nations and national states, and discusses how four main types of nations (ethnic, civic, plural and class) cope with globalisation. The article builds on the assumption that the ‘foreign policy’ field, notably the capacity of states to shape popular global policies, must be included in discussions of the future of the national state.
Revisiting the Health Belief Model: Nurses applying it to young families and their health promotion needs
Authors: Roden Janet
Published: February 2004

The Health Belief Model (HBM) was reviewed with the aim of modifying it so that it reflected a health promotion stance for young families. Since this model's inception, health professionals like nurses have been involved in using the HBM to guide their practice. It is argued that to assist families, nurses now need a model that is focused on ‘health.’ In support of this approach, reorienting the HBM and basing it on ‘positive’ health definitions associated with health promotion, by modifying it through adding the constructs ‘perceived behavioral control’ (representing health locus of control) and ‘behavioral intention’ from Ajzen will provide nurses with a more appropriate and useful model for interacting with families and their preschool children. A summary of positive and negative aspects of the modification of the HBM is presented, followed by a strategy for the process of validating the revised HBM for young families.
Criterion validity, test‐retest reliability and sensitivity to change of the St George urinary incontinence score
Authors: Blackwell A.L. , Yoong W. , Moore K.H.
Published: February 2004

OBJECTIVE

To assess the criterion validity, test‐retest reliability and the sensitivity to change after treatment of the St George Urinary Incontinence Score (SGUIS).

PATIENTS AND METHODS

Women presenting with urinary incontinence completed two SGUIS tests one week apart. A frequency‐volume chart (FVC) was completed before the first attendance and the women had a 1‐h pad test before treatment. Patients were treated conservatively under the care of a urogynaecologist or nurse continence advisor, or surgically with an open or laparoscopic colposuspension. After treatment, the SGUIS, FVC and 1‐h pad test were repeated.

RESULTS

The SGUIS correlated moderately well with the number of leaks per week (Spearman's r = 0.610, 95% confidence interval 0.516–0.689, P < 0.001) but less well with the 1‐h pad test loss (r = 0.257, 0.124–0.380, P = 0.002). The test‐retest reliability was acceptable, as the mean (sd) difference between the first and second SGUIS was 0.337 (2.675), with limits of agreement of −5.012 to −5.686. The change in the SGUIS after treatment correlated well with the improvement in the number of leaks per week (r= 0.742, 0.662–0.805, 156 samples, P < 0.001) but not as well with the change in 1‐h pad test loss (r= 0.531, 0.405–0.636, 151, P < 0.001), although the trend was similar.

CONCLUSION

The criterion validity of the SGUIS appeared adequate for both the number of leaks per week on the FVC and leakage on the 1‐h pad test. The statistical reproducibility of the test was adequate and appeared more responsive to change after treatment than the other measures. The score is suitable for rapid self‐administration by patients with a range of incontinence types, unlike most other currently available test instruments.
Robot‐assisted laparoscopic adrenalectomy: preliminary UK results
Authors: Undre S. , Munz Y. , Moorthy K. , Martin S. , Rockall T. , Vale J. , Darzi A.
Published: February 2004

Authors from London describe the early results from the UK in the use of robot‐assisted laparoscopic adrenalectomy. In a small group of patients they found that patients could be treated early, with early discharge from hospital.

The use of retrograde balloon dilatation of PUJ obstruction is revisited by authors from Plymouth, who review their 10 years of experience with this technique. They found that the procedure gave good symptomatic relief in 76% of their patients, but found no relationship between symptom relief and renographic improvement. In a few patients with a long‐term follow‐up there was symptomatic improvement and good maintenance of split renal function.

OBJECTIVE

To describe the results of our first two cases of laparoscopic adrenalectomy using the da VinciTM surgical system (Intuitive Surgical, Inc., Mountain View, CA, USA).

PATIENTS AND METHODS

Amongst 75 robot‐assisted procedures performed at our institution, two patients underwent robot‐assisted laparoscopic adrenalectomy. The set‐up time, procedure time, hospital stay, complications and outcomes were recorded.

RESULTS

Both operations were completed successfully using the robot; the mean (range) set‐up time was 31 (25–37) min and mean procedure time 118.5 (107–130) min. One patient had a postoperative pulmonary embolus and was discharged 5 days after surgery; the second patient was discharged after 3 days. There were no intraoperative complications; both patients were well at the 1‐year follow‐up

CONCLUSIONS

Robot‐assisted laparoscopic adrenalectomy is technically feasible and can be conducted efficiently and safely with the da Vinci surgical system.
A preliminary study of natural‐fill radiotelemetered ovine fetal cystometry
Authors: Thiruchelvam N. , Godley M.L. , Farrugia M.K. , Cuckow P.M.
Published: February 2004

OBJECTIVE

To determine whether fetal cystometric studies by radiotelemetry are feasible in the fetal lamb, and potentially suitable for chronically monitoring fetal bladder pressures in an experimental fetal model of bladder outlet obstruction (BOO), as in utero BOO (e.g. caused by posterior urethral valves) results in significant postnatal bladder dysfunction but the pathophysiological progression of fetal bladder maldevelopment remains poorly understood.

MATERIALS AND METHODS

The procedure required fetal sheep surgery and anaesthesia. Radiotelemetry implants comprised catheters that transmitted pressure fluctuations to an implant body; data were then transmitted using radio frequency to a receiver that passed this information to a computer. Four fetuses were used with different methods of catheter placement to optimize the technique.

RESULTS

Recordings were possible in three of the four sheep; during observation there were: (i) quiet periods with no abdominal or bladder pressure rises; (ii) synchronous activity in the bladder and abdomen; and (iii) discriminate activity, associated with intravesical activity only. Four patterns of discriminate bladder activity were observed, defined as void, immature void, staccato activity and ‘unstable’ type activity.

CONCLUSIONS

Radiotelemetry cystometry for long‐term monitoring is feasible in the experimental fetus without causing death or morbidity, or inhibiting growth. The method can discriminate reproducible patterns of detrusor activity. Recorded ‘voiding’ types were consistent between experiments and as reported in other fetal animal studies.
Incidental carcinoma of the prostate: clinicopathological, stereological and immunohistochemical findings studied with logistic regression and self‐organizing feature maps
Authors: Mattfeldt T. , Trijic D. , Gottfried H.‐W. , Kestler H.A.
Published: February 2004

OBJECTIVE

To identify significant predictive factors determining category T1a and T1b in incidental prostatic carcinoma with classical and neural multivariate data analysis methods.

MATERIALS AND METHODS

Incidental prostatic carcinomas diagnosed in our department during 1990–99 (66 cases) were re‐examined. Besides acquiring routine clinical and pathological data the tumours were assessed by scoring immunohistochemistry for proliferative activity and p53‐overexpression. Tumour vascularization (angiogenesis) and epithelial texture variables were investigated by quantitative stereology. The data were evaluated by classical statistical methods (t‐test, correlation analysis, logistic regression). Moreover, self‐organizing feature maps (SOMs) were applied as an exploratory approach to unsupervised data analysis by artificial neural networks.

RESULTS

The proliferative fraction, p53 overexpression of tumour cell nuclei, preoperative prostate‐specific antigen value and density of capillary vascularization correlated with the Gleason score in incidental prostatic carcinoma. In a stepwise logistic regression analysis with the tumour categories T1a and T1b as dependent variables, the Gleason score and the volume fraction of epithelial cells were significant independent predictors of the tumour category. The cases could be grouped into clusters of different degrees of malignancy using SOMs.

CONCLUSIONS

Texture variables of tumour cells are of central importance for the extent of propagation in the prostate in incidental prostatic adenocarcinomas. Gleason score and quantitative stereological estimates of the volume fraction of tumour cells are significant predictors of T1a and T1b categories of incidental prostatic carcinoma. Unsupervised clustering of T1 prostate carcinoma cases by SOMs correlates well with the dichotomous classification into T1a and T1b according to the UICC.
Expression of vascular endothelial growth factor protein in human renal cell carcinoma
Authors: Jacobsen J. , Grankvist K. , Rasmuson T. , Bergh A. , Landberg G. , Ljungberg B.
Published: February 2004

OBJECTIVE

To evaluate the effect of vascular endothelial growth factor (VEGF, one of the most important angiogenetic factors) in renal cell carcinoma (RCC) by analysing many RCCs for the expression of immunohistochemical (IHC) VEGF‐staining related to clinicopathological findings and survival.

PATIENTS AND METHODS

VEGF immunostaining was examined with the tissue microarray (TMA) method on tumour samples from 229 patients and validated in 71 by ordinary tissue sections (TS). IHC VEGF expression was quantified by estimating the volume density and staining intensity on a three‐grade scale.

RESULTS

In most RCCs there was VEGF staining in the cell cytoplasm and membrane. In cell membranes the VEGF expression declined with storage time. IHC VEGF expression analysed by TMA and TS gave corresponding results. There was no difference in VEGF expression among conventional, papillary and chromophobe RCCs. There were significant correlations between VEGF expression and tumour size and stage. In univariate analysis VEGF expression correlated with survival, especially in conventional RCCs; this prognostic information was lost in multivariate analysis. The VEGF staining intensity correlated only with VEGF expression but not with any clinicopathological factors.

CONCLUSIONS

VEGF protein was present in most RCC cells. There was no difference in VEGF expression among the different RCC types. The correlation between VEGF expression and tumour stage and with prognosis indicates the significance of VEGF within tumour growth and progression in RCC.