showing 36 of ~574560 from 574555 documents
The Community Response to Aircraft Noise Around Six Spanish Airports
1993
Abstract The community response to aircraft noise has been studied through a social survey. A total of 1800 persons living in the vicinity of six major Spanish airports have been interviewed at their homes concerning the environmental quality of the area, dissatisfaction with road traffic noise and aircraft noise, activities interfered with by noise, most disturbing aircraft types, and subjective evaluation of airport impact. All the responses obtained in this survey have been compared with aircraft noise levels corresponding to the residence locations of the people interviewed (values of NEF levels were calculated with the INM model). The results obtained in this work allow one to evaluate…
Association between plasma ionized calcium and lactate concentration
1993
ISE are not suitable for the measurement of ionized calcium under clinical conditions when anions like acetate, lactate or malate are present in concentrations of about 5–10 mmol/l.
Determination of U-Pb ages of zircons by direct measurement of the 210Pb/206Pb ratio
1993
Abstract Precise measurements of the 210Pb/206Pb ratio in zircons permits, for the first time, the determination of complete U-Pb ages by measurement of Pb isotopes only, without determination of the U-Pb ratio by isotope dilution. The 238U daughter isotope 210Pb is generally in radioactive equilibrium with 238U; however, the very short half-life of 210Pb (22.3a) results in extremely low 210Pb/206Pb ratios of ∼ 10−8, especially for Archaean zircons. These ratios have been determined using a Finnigan MAT 262® mass spectrometer equipped with a high abundance sensitivity lens system (RPQ). The accuracy of the 210Pb method has been tested on nine different zircon samples with 207Pb/206Pb ages f…
Prevalence of diabetic neuropathy with somatic symptoms
1993
In a door-to-door survey conducted in two municipalities of Sicily, we ascertained the prevalence of diabetic neuropathy. Our case-finding was restricted to subjects with somatic symptoms. During phase 1, we administered a screening instrument for peripheral neuropathy to 14,540 persons residing in Santa Teresa di Riva (Messina Province) and Terrasini (Palermo Province). During phase 2, neurologists evaluated those subjects who had screened positive. Diagnoses were based on clinical criteria only, and were reviewed by an adjudication panel. We found 39 persons (27 women, 12 men) affected by diabetic neuropathy. The crude prevalence, as of November 1, 1987, was 268.2 cases per 100,000 popula…
Collisional relaxation measurements on Pb+ hyperfine levels
1993
The time constants for population relaxation of optically pumped Pb+ ions in a Paul ion trap have been determined in a He buffer gas atmosphere with additional components of other gases. For the 6P1/2 ground state of Pb+ and an ion temperatur of 104 K we find cross sections of 0.72(0.33)·10−17 cm2; 0.59(0.38)·10−15 cm2; and 2.56(0.74)·10−14 cm2 for He, N2 and O2, respectively. The error includes an estimated 20% uncertaincy in the pressure calibration of a residual gas analyser.
The complex life-cycle of a polymorphic prokaryote epibiont of the photosynthetic bacterium Chromatium weissei
1993
In natural populations of the anaerobic phototrophic bacterium Chromatium weissei, many cells support a prokaryotic epibiont. This epibiont appears in several forms, all from the life cycle of a single species. A typical epibiont consists of one to five flattened coccoid cells stacked one above the other, perpendicular to the C. weissei surface. The cells at the proximal and distal ends of the stack are 0.6 μm in diameter and 0.8 μm in length; mid-stack cells are slightly shorter. A typical three or four cell stack is 2 μm in length. Small mesosome-like inclusions in the distal cell are involved in the development of ‘droplet’ shaped cells which are released from the end of each stack. Thes…
Kuntscher nailing of femoral shaft fractures in children and adolescents.
1993
We have reviewed 29 cases of very unstable diaphyseal fractures of the femur in children and adolescents treated by Kuntscher nailing. Follow up was for at least 5 years, and in most cases until after the end of growth. There were no post-operative complications, and the mean overgrowth of the femur was 7.06 mm. There was growth disturbance of the proximal femur in one case, but this did not interfere with function. We believe that Kuntscher nailing is indicated in children and adolescents with unstable high velocity fractures of the femoral shaft.
Measurement of the and B− meson lifetimes
1993
Abstract The lifetimes of the B 0 and B − mesons have been measured with the ALEPH detector at LEP. Semileptonic decays of B 0 and B − mesons were partially reconstructed by identifying events containing a lepton with an associated D ∗+ or D 0 meson. The proper time of the B meson was estimated from the measured decay length and the momentum and mass of the D -lepton system. A fit to the proper time of 77 D ∗+ l − and 77 D 0 l − candidates, combined with a constraint on the lifetime ratio ( τ − τ 0 ) arising from the relative rates of observed D ∗+ l − and D 0 l − events, yielded the following lifetimes: τ 0 =1.52 −0.18 +0.20 ( stat. ) −0.13 +0.07 ( syst. ) ps , τ − = 1.47 −0.19 +0.22 ( sta…
Synthesis of 3-triazenopyrroles
1993
Abstract The 3-triazenopyrroles, a new class of pyrrole derivatives, were synthesized in quantitative yield by coupling 3-diazopyrroles with secondary amines.
The radiation class: a set of temporal gauges
1993
We present in a path integral framework a class of gauges for QED that are both temporal and yet do not display the notorious singularity of the naive temporal gauge. These gauges follow from a generalised radiation gauge, where the Coulomb gauge fixingsis “smeared out”. We show that the use of two gauge fixings necessitates the incorporation of gauge dependent Coulomb interactions. The correctness of our theory is demonstrated in two ways: we can reduce to the true degrees of freedom and we show that it reproduces some gaugeinvariant results of perturbation theory. Although Landshoff's α prescription for the temporal gauge can be understood as a limit of our class, extra terms also appear.…
Line mixing in the stimulated Raman spectrum of the ν1 band of SiH4 at 0.4–1.0 bar
1993
The stimulated Raman spectrum of the ν1 band of SiH4 has been recorded at 0.4 and 1.0 bar pressures and room temperature. Line mixing of the fine structure components of this spectrum was taken into account in a calculated profile by considering coupling between the main transitions and using a simple model (strong collision model, SCM) for the relaxation matrix.
Do p annihilations at rest choose the Eightfold way?
1993
Dynamical selection rules observed in pp annihilation at rest are linked to relations between SU(3) invariant amplitudes. The ϱπ puzzle, the KK suppression in P wave, and the unexplained production rates of πa2 (1320) are shown to be manifestions of one SU(3) amplitude ratio. The dynamical selection rules observed in the production of strange mesons lead to symmetries in SU(3) amplitudes. We conjecture that these symmetries reflect the underlying quark-gluon dynamic. It is shown that the contribution of annihilation diagrams to important annihilation channels like ϱ0π0 or ηω is small or vanishes. Hence rearrangement must play an important role. The use of SU(3) relations in the context of N…
Brain slow waves preceding time-locked visuo-motor performance.
1993
According to previous findings (Konttinen and Lyytinen, 1992), the slow brain negativity preceding the trigger pull in rifle‐shooting tends to be decreased in successful shots among experienced marksmen, whereas no such pattern is found among inexperienced subjects. This effect was interpreted as resulting mainly from optimal arousal. However, another explanation is examined here. The aim of the experiment was to investigate slow electrocortical changes associated with motor regulation and visual aiming related to shooting performance. Four variations on a shooting task were used, in which the visual and motor components were contrasted. Motor activity related to gun stabilization was found…
Assessment of the cardiostimulant action of propionyl-L-carnitine on chronically volume-overloaded rat hearts.
1993
Chronic volume overload was induced in young rats of Wistar strain by surgical opening of the aorto-caval fistula. Three months later, during in vitro perfusion with exogenous palmitate, left ventricular function and energy turnover (QO2) of hypertrophied hearts were severely depressed. This seemed to be related to impaired long-chain fatty acid utilization, as reflected by decreased 14CO2 production from U-14C-palmitate and decreased tissue levels of L-carnitine. Another group of rats exposed to chronic volume overload was pretreated for 2 weeks before sacrifice with propionyl-L-carnitine (250 mg/kg/day), and the hearts were perfused with 1.2 mM palmitate and 10 mM propionyl-L-carnitine. I…
Heavy-quark production in two-photon collisions
1993
Abstract Heavy quarks are copiously produced in two-photon collisions at e + e − colliders. We present the inclusive production rates and the final state distributions of the quarks, including QCD radiative corrections for the leading subprocesses. The results are compared with recent measurements of charmed particle production at PETRA and PEP, and predictions are given for TRISTAN and LEP energies.
Synthetic O-glycopeptides as model substrates for glycosyltransferases
1993
Abstract A new approach to O-glycopeptides of the glucosamine type is described. N-Urethane protected, peracetylated glucosamine is converted into its 1-thio (1-bromo) derivative and used for glycosylation of a variety of protected serine or threonine derivatives as acceptors. The urethane group is easily exchanged for the natural N-acetyl moiety and O-deacetylation is achieved with hydrazine/methanol. The resulting O-GlcNAc derivatives are subjected to an enzymatic galactosylation procedure using β-1,4-galactosyltransferase (EC 2.4.1.22) to furnish O-glycopeptides of the neolactosamine type.
Lifetime measurements of highly excited Rydberg states of strontium I
1993
Lifetimes of Rydberg states of the triplet-series 5s ns3S1 withn = 19–23, 35 and 5s nd3D3 withn = 18–20, 23–28 in the spectrum of neutral strontium have been determined. Observation of the exponential decay after excitation by a pulsed laser in a fast atomic beam and subsequent state-selective field ionization was employed. The lifetimes of the states of the3S1-series show the expectedn*3 dependence on the effective principal quantum number, while the3D3-series is disturbed by configuration mixing. Furthermore, state re-populations induced by black-body radiation have been observed.
Cognitive functioning and anhedonia in subjects at risk for schizophrenia
1993
This study investigated the performance of individuals with familiar loading of schizophrenia (healthy siblings of schizophrenic inpatients) on three neuropsychological tasks assumed to require frontal lobe functions: Trail Making Test (TMT), verbal fluency and Wisconsin Card Sorting Test (WCST). Healthy siblings of schizophrenics differed in performance from healthy controls not only on the WCST, but also on the Trail Making Test and the verbal fluency task. Furthermore, scores of physical anhedonia, assessed in a self-report rating scale (Chapman et al., 1976) were also significantly higher in the high risk group than in the control sample. However, healthy siblings of schizophrenics did …
A Study on Plastic Shakedown of Structures: Part I—Basic Properties
1993
For a continuous elastic-perfectly plastic solid body subjected to a combination of cyclic (mechanical and/or kinematical) load and of a steady (mechanical) load such as to produce plastic shakedown (i.e., alternating plasticity), a number of characterizing properties are established and discussed. The conditions for the body’s transition from plastic shakedown to ratchetting are also addressed.
Theoretical analysis of hole self-trapping in ionic solids: Application to the KCl crystal.
1993
A method for the calculation of the hole self-trapping (ST) energy in ionic crystals is proposed. It combines model-Hamiltonian and quantum-chemical approaches. An artificial path for the ST process has been suggested containing (a) a free hole not interacting with the lattice vibrations; (b) a free-hole wave packet localized in a small crystal volume in the form of the real ST state, all crystal ions being in their perfect lattice positions; (c) the final ST state of the hole, accompanied with a corresponding lattice relaxation, including strong displacements of ions belonging to the hole region. Some intermediate states might be adopted between (a) and (b) in order to simplify the calcula…
USO DELLA TUNICA VAGINALE DEL TESTICOLO NELLA CHIRURGIA DELL'IPOSPADIA
1993
Urethrocutaneus fistulas are the most common complication of surgery for hypospadias. In five patients, fistulas of this type were repaired with patches of tunica vaginalis to prevent fistula recurrence. Our experience and that of others suggest that tunica vaginalis autografts can be used for treatment of a variety of urethral problems in children.
Kinine, Kallikreine und Kaskadensysteme
1993
Die molekularen Grundlagen der Bioregulation sind bisher nur in Ansatzen verstanden. Steuerung und Regulation der vielfaltigen physiologischen Funktionen eines multizellularen Organismus sind namlich extrem komplex. Mit den modernen Methoden der Molekularbiologie, Zellbiologie und Immunologie versucht man, die molekularen Details regulatorischer Systeme Schritt fur Schritt aufzuspuren. Fur die Wissenschaft interessant sind dabei vor allem molekulare Netzwerke, die an Erkrankungen des Herz-Kreislauf-Systems und des Immunsystems, den haufigsten Todesursachen industrialisierter Lander beteiligt sind. Im folgenden wird anhand der Kinine, einer Gruppe von blutdrucksenkenden und entzundungsforder…
Lectura y lectores en el Madrid del siglo XIX
1993
Aspects of the kinematic history and mechanisms of superposition of the proterozoic mobile belts of eastern Central Africa (northern Malawi and south…
1993
Abstract Commonly the Proterozoic tectonic evolution of the Central African basement is subdivided into three major events: (1) the Ubendian (∼2300−1800 Ma), (2) the Irumide (∼1350−950 Ma), and (3) the Pan-African (∼900−450 Ma) orogenic cycles. Relics of the Ubendian event are granite intrusions and, possibly, an amphibolite- to granulite-facies metamorphism. The Ubendian orogeny was followed by deposition of clastic sediments (Muva supergroup). In northern Malawi these sediments and the underlying basement were then thrust to the east-southeast/southeast during the Irumide orogeny. Horizontal shearing along subvertical zones (i.e. the Ubendian belt) was associated with subhorizontal crusta…
Excitonic effects in two-LO-phonon resonant Raman scattering.
1993
Abstract The role of electron-hole correlation in resonant Raman scattering by two LO-phonons is analyzed. A theoretical model including excitons belonging to the discrete and continuous spectra as virtual intermediate states in the Raman process and valid for incident energies below and above the gap is developed. For the exciton-phonon coupling the Frohlich Hamiltonian is considered. The most important contribution to the Raman scattering efficiency corresponds to the continuous→discrete→discrete exciton transition, followed by the discrete→discrete→discrete and the continuous→continuous→discrete ones. The model is tested for GaP, where the scattering efficiency data are available around …
Shear elasticity of mixed cyanide orientational glass
1993
Four mixed crystals of KBr:KCN and NaCN:KCN, complemented by KCN, have been investigated by torque-shear measurements. The real and imaginary parts of the shear compliance ${\mathit{s}}_{44}$ at a measuring frequency of 2 Hz have been determined. Zero-field-cooling--field-cooling--remanent-shear-strain cycles have been performed. For (KBr${)}_{0.47}$(KCN${)}_{0.53}$ the creep after zero-field cooling and the elastic aftereffect after field cooling have been followed within a time window from 0.1 to ${10}^{4}$ s. Results on the nonlinear part of the shear compliance have been obtained. It is shown that the field-cooled strain represents the static limit of the elastic response. The results a…
A field method for measuring the thermal infrared emissivity
1993
Abstract In this work, a field method for measuring thermal infrared emissivities is proposed which is based on the box method, initially developed by Buettner and Kern (1965) for laboratory measurements. A theoretical analysis was made of the measurement carried out using the box and a correcting factor to Buettner and Kern's technique has been determined. Buettner and Kern's method has been modified to use radiative temperatures measured with a radiothermometer instead of radiance measurements. The walls of the box used and the cold lid was made of polished aluminium and the hot lid was made of black-painted anodized aluminium and it was heated in the field by solar radiation. With this m…
Full characterization of low-noise HEMTs using only noise figure measurements
1993
A method for the complete characterization of microwave transistors in terms of noise, gain and scattering parameters using a computer-controlled noise figure measuring set-up only is presented. Selection of the optimum measuring conditions, all the steps of the experimental procedure, the data collecting and processing to derive all the parameters, are fully driven by an original (unpublished) software, even without the presence of an (unskilled) operator. Results are presented about the complete characterization of a series of ten pseudomorphicHEMTs in the 8-16 GHz range. The S-parameters are also compared with those measured by an ANA.
On the Occurrence of Caffeoyltartronic Acid and Other Phenolics in Chondrilla juncea
1993
Abstract Caffeoyltartronic acid and other eleven phenolic com pounds were identified in the MeOH extract of Chondrilla juncea: the flavonoids luteolin, luteolin-7-glucoside, luteolin-7-galactosylglucuronide and quercetin-3-galactoside; the phenolic acids protocatechuic, caffeic, chlorogenic, isochlorogenic and isoferulic and the coumarins cichoriin and aesculetin. The taxonomic im plications of these com pounds have been discussed.
Dynamical selection rules in p annihilation at rest
1993
Abstract The branching ratios for p p annihilation at rest into two mesons show the existence of dynamical selection rules. The ratios for some annihilation modes are small even though much larger rates should be expected on the basis of statistical models. Dynamical selection rules are observed in annihilations in which strange mesons are produced, and in annihilations into two isovector mesons. The selection rules seem - to first order - not to depend on the spins or orbital angular momenta of the p p atom or of the two mesons produced. This observation suggests an underlying symmetry. It is argued that this symmetry is SU(3).
Risk of predation and foraging sites of individuals in mixed-species tit flocks
1993
Abstract Abstract. Foraging sites of individual willow tits, Parus montanus, and crested tits, P. cristatus, on spruce were studied in a winter when the risk of predation from pygmy owls, Glaucidium passerinum, was high and in a winter when it was low. Mixed-species flocks consisted of two crested tits (a pair) and three to six willow tits. The risk of predation from owls is likely to be highest on the most exterior tree parts. Female crested tits foraged further out on the branches than other individuals when predation risk was low, but foraged in the safer sites close to the tree trunk when the risk was high. Male crested tits retained both their relative distance to the trunk and their r…
Decay properties of exoticN≃28 S and Cl nuclei and theCa48/46Ca abundance ratio
1993
Beta-decay half-lives and \ensuremath{\beta}-delayed neutron-emission probabilities of the very neutron-rich nuclei $^{44}\mathrm{S}$ and $^{45--47}\mathrm{Cl}$ have been measured. These isotopes, which lie at or close to the N=28 magic shell, were produced in interactions of a 60 MeV/u $^{48}\mathrm{Ca}$ beam from GANIL (Grand Acc\'el\'erateur National d'Ions Lourds) with a $^{64}\mathrm{Ni}$ target, and were separated by the doubly achromatic spectrometer LISE (Ligne d'Ions Super Epluch\'es). Their decay was studied by a \ensuremath{\beta}-n time correlation measurement. The results are compared to recent model predictions and indicate a rapid weakening of the N=28 shell effect below $_{2…
Gamma-radiation ageing of a low density polyethylene. Effects of irradiation temperature and dose rate
1993
Abstract Ageing due to gamma radiation of a low density polyethylene at various dose rates and temperatures is studied; the effect of thermal treatment only is also considered. The modifications induced in the molecular and crystallinity behaviour of the polymer are investigated by means of gel extraction, measurements of intrinsic viscosity and thermal analysis. Results indicate the occurrence of both crosslinking and oxidative degradation; the extent of the latter increases on decreasing the irradiation dose rate and on increasing the irradiation temperature. Some exceptions are found because of the increase in the mobility of free radicals at high temperature. These effects modify also t…
Antiproton-proton annihilation at rest into two mesons
1993
Abstract Branching ratios for antiproton-proton annihilations at rest into two mesons are given. The data were obtained at LEAR by stopping antiprotons in a liquid hydrogen target. Both charged and neutral annihilation products were detected in the Crystal Barrel detector. Representative data are presented, and their bearing on the general picture of annihilation dynamics is discussed. In addition, preliminary branching ratios for two-body radiative annihilations are given.
Cadmium induced metallothionein in hepatopancreas of Procambarus clarkii: Quantification by a silver-saturation method
1993
Abstract 1. Cadmium induced metallothionein (MT) in crayfish hepatopancreas was measured by silver-saturation method. 2. An increase in MT content was recorded in crayfish hepatopancreas after 12 hr of exposure to 10 mg Cd/l. 3. There was found to be a linear relationship between MT concentrations in hepatopancreas and cadmium concentration in the water. 4. MT levels in hepatopancreas of 20 mg Cd/l exposed crayfish were 7-fold higher than those in control animals.
A prediction model for field drying of hay using a heat balance method
1993
Abstract A hay drying model with a multi-layer representation has been developed. This model, based on a heat balance method, was designed to compute hay drying dynamics in the field. It was implemented for hay spread over a field or in windrows. The necessary inputs are: (1) meteorological data (temperature, humidity, wind speed, solar and atmospheric radiation); (2) biological characteristics of the plant; (3) hay physical parameters (depth, leaf area index). The output provides time-dependent cumulative water losses and changes in water content and temperature in the different layers. The model was tested against data measured under experimental conditions with different kinds of grass (…