Showing papers by "Technical University of Denmark published in 1985"
TL;DR: In this paper, a theoretical and experimental investigation of injection locking of semiconductor lasers is presented, taking into account the dependence of refractive index on the carrier density expressed by the linewidth enhancement factor α.
Abstract: We present a theoretical and experimental investigation of injection locking of semiconductor lasers. The theoretical analysis takes into account the dependence of refractive index on the carrier density expressed by the linewidth enhancement factor α. Locking conditions and dynamic stability are analyzed. The nonzero value of α results in an increased locking bandwidth, where only part of the range corresponds to a dynamically stable state. Asymmetric characteristics are obtained for the locked power and phase as a function of frequency detuning between the master and slave laser. Outside the stable range, light injection gives rise to beat phenomena and intensity pulsations. The theoretical results were confirmed by experiments on 830 nm CSP lasers and 1.3 μm BH lasers. The experiments include the first measurements of locking bandwidth characteristics reported for 1.3 μm lasers. Power spectra are recorded under locked and near-locked conditions and compared with theory. The 1.3 μm lasers are found to have a better dynamic stability than 830 nm lasers. Even so, the stability problems may exclude the particular application of injection locking where phase modulation is generated for coherent transmission.
432 citations
TL;DR: In this article, a systematic classification of the effects of transverse cracking on the stress-strain response of composite laminates is presented, and an assessment of the ply discount method for predicting stiffness reductions at crack saturation is also made.
Abstract: A systematic classification of the effects of transverse cracking on the stress-strain response of composite laminates is presented. Stiffness reductions resulting from transverse cracking in glass/epoxy and graphite/epoxy laminates from crack initiation to crack saturation are predicted using the stiffness-damage relationships developed by the author in a previous work. Good agreement with the experimental results is found. An assessment of the ply discount method for predicting stiffness reductions at crack saturation is also made.
369 citations
TL;DR: Fimbriae are long, threadlike protein polymers found on the surface of many strains of Escherichia coli that confer on pathogenic strains the ability to adhere to and colonize various specific host epithelia.
Abstract: Fimbriae are long, threadlike protein polymers found on the surface of many strains of Escherichia coli. The presence of fimbriae has been found to be significantly correlated with pathogenicity, and specific fimbriae confer on pathogenic strains the ability to adhere to and colonize various specific host epithelia. A surprising variety of fimbrial adhesions have been found in E. coli; several unrelated groups of such proteins have been extensively characterized. Fimbriae of E. coli are strongly immunogenic. Their continuous interaction with host defenses has imposed heavy selective pressure on them, leading to a fine balance between functional necessity and maximal immunologic diversity. These important virulence factors may be exploited in various ways in the production of vaccination agents. Vaccines based on E. coli fimbriae have proved extremely successful in the veterinary sector, and several types of immunization are currently being tested in humans.
304 citations
TL;DR: Two simple two-layer eddy viscosity models, which facilitate analytical solutions, are presented in order to describe the velocity field and associated shear stress in a combined current wave motion as mentioned in this paper.
266 citations
TL;DR: It was found that the dnaA gene was autoregulated over a 30-fold range by the activity of dnA protein.
Abstract: Regulation of the dnaA gene, which codes for an essential factor for the initiation of replication from the chromosomal origin, was studied in vivo using transcriptional and translational gene fusions. We found that the dnaA gene was autoregulated over a 30-fold range by the activity of dnaA protein. Expression from the dnaA promoter region of a dnaA"lacZ fusion was inhibited up to sevenfold by surplus dnaA protein and was stimulated up to fivefold upon thermoinactivation of the mutant protein in five different dnaA(Ts) strains. The autoregulation was found to be exerted at transcription from the major dnaA promoter and was eliminated by deletion of sequences around position -65 of this promoter where a 9-bp sequence, which is also found four times in the chromosomal origin, is located.
189 citations
TL;DR: Four genes, designated fimA, B, C, and D were found to be involved in the synthesis of the fimbriae, and they encoded proteins that in their processed form appeared with apparent molecular weights of 16.6 kd, the 16.
Abstract: The genes responsible for the expression of type 1 fimbriae, produced by the majority of E. coli strains, have been cloned from an E. coli K12 strain. The “passenger” DNA from an initial cosmid clone was reduced in size and subcloned in pACYC184 and pBR322 vectors. A DNA fragment of around 8 kbp was found to be required for the biosynthesis of type 1 fimbriae. This was further studied by transposon-mediated insertional inactivation and by BAL31-mediated deletions. Four genes, designated fimA, B, C, and D were found to be involved in the synthesis of the fimbriae. They encoded proteins that in their processed form appeared with apparent molecular weights of 16.5 kd, 23 kd, 26 kd, and 89 kd, the 16.6 kd polypeptide being the fimbrial subunit. The order to the genes was found to be: fimB, fimA, fimC, and fimD, organized in three transcriptional units.
180 citations
TL;DR: In this article, a group of 32 and 16 subjects of both sexes were exposed in an environmental chamber to radiant asymmetry caused by a cool wall, a warm wall, and a cool ceiling, each subject was tested individually while seated and clothed at 0.6 clo.
178 citations
TL;DR: The mass balance of the Greenland ice sheet is estimated on the basis of 0 bserva tions of ice thickness, accumulation rate, surface velocities, and surface strain-rates as discussed by the authors.
Abstract: The mass balance of the Greenland ice sheet a t Dye 3 is estimated on the basis of 0 bserva tions of ice thickness, accumulation rate, surface velocities, and surface strain-rates . The calculations indicate a rate of increase of surface elevation of 3 cm / year, with 95% confidence limits of -3 cm/ year and +9 cm/ year. Previous estimates of the mass balance of the Greenland ice sheet by the same method reported large imbalances; these are most probably due to lack of precise data and the use of quantItIes measured at the surface as representative of depth-averaged quantities. The most reliable observations indicate that the interior regions of the Greenland ice sheet are at present thickening at a rate of a few centimetres per year; a contributing cause for this may be the slow thinning of a bottom layer of relatively soft Wisconsin ice. RESUME. Bilan de masse de l'lndlandsis Groenlandais a Dye 3. Le bilan de masse est estime it partir des mesures d'epaisseur, taux d'accumulation, vitesses et vitesses de deformation superficielles. Le calcul don ne un epalss lssement de 3 cm an- 1 avec un intervalle de confiance, au seuil de 95%, allant de -3 cm an- 1 it +9 cm an-I. Les estimations anterieures du bilan de l'lndlandsis obtenues par la meme methode sont examinees. On en deduit que les valeurs de bilan tres eloignees de l'equilibre sont certainement dues au manque de donnees preclses et/ ou a I'utilisation de donnees superficielles comme valeurs moyennes sur une
167 citations
TL;DR: In this article, the mechanism of glass formation is discussed, which results in crystallization of the particles into a mixture of α-Fe and δ-C. The authors show that the particles of a metallic glass are formed at 523 K.
Abstract: Iron pentacarbonyl has been thermally decomposed in an organic liquid. M\"ossbauer spectroscopy and x-ray diffraction studies show that the sample contains small particles of a metallic glass. Annealing of the particles at 523 K results in crystallization of the particles into a mixture of \ensuremath{\alpha}-Fe and \ensuremath{\chi}-${\mathrm{Fe}}_{5}$${\mathrm{C}}_{2}$. The mechanism of glass formation is discussed.
139 citations
TL;DR: The rnpA gene, coding for the protein component of ribonuclease P (RNase P), was allocated to the dnaA region at 83 min of the E. coli K-12 map, and a very basic polypeptide with an Mr of 13773 could be deduced, which is concluded to be the rNPA gene product, and is theprotein component of RNase P.
108 citations
TL;DR: Intrinsic thermal clothing insulation and surface air insulation were measured on human subjects by the use of indirect calorimetry and showed that intrinsic clothing insulation was maximal in the standing position.
Abstract: Intrinsic thermal clothing insulation and surface air insulation were measured on human subjects by the use of indirect calorimetry. Four male clothing ensembles (0-1-1 -8 clo) and three female clothing ensembles (0-2-1-2 clo) were investigated. Using the standing position as a reference, the influence of sitting, bicycling (40r.p.m., 20 W), walking (3-75 km hour−1) and of light packing work on the thermal insulation was studied. The influence of an air velocity of 11ms−1 on thermal insulation during the standing and walking conditions was investigated. The results showed that: (i) intrinsic clothing insulation was maximal in the standing position. It was reduced by 8-18% in the seated position and by 30-50% during bicycling and walking. An air velocity of 11ms−1 did not influence the intrinsic clothing insulation during walking, but decreased it by 18% in the standing position; (ii) surface air insulation varied with activity and air velocity, but not with clothing. It was increased by up to 25%...
TL;DR: It is observed for the first time a single Sine-Gordon soliton trapped in an annular Josephson junction, which offers a unique possibility to study undisturbed soliton motion.
Abstract: We have observed for the first time a single Sine-Gordon soliton trapped in an annular Josephson junction. This system offers a unique possibility to study undisturbed soliton motion. In the context of perturbation theory, the soliton may be viewed as a relativistic particle moving under a uniform force with damping. Accordingly our experimental results are displayed directly in a force-versus-momentum plane, where they may be described by a theoretically derived universal curve.
TL;DR: Reflectance spectrophotometry is applied to flow-injection measurements of pH and assays of ammonia and urea with the aim of demonstrating the principle and testing the performance of optosensors integrated into microconduits as mentioned in this paper.
TL;DR: In this article, a general formula for the distribution of the annual maximum covering both the independent and dependent case has been derived, and the use of the formula has been exemplified.
TL;DR: In this paper, the influence of roll radius to plate thickness ratio, friction, surface preparation and reduction in rolling on the bond strength obtained in Al-Al cold roll bonding has been calculated.
TL;DR: These sequences show that barley protein Z is homologous with human α1‐antitrypsin, human otj‐antichymotryps in, human antithrombin III, mouse contrapsin and chicken ovalbumin, and inhibition of microbial or pancreatic serine proteases could, however, not be associated with protein Z.
TL;DR: In this paper, the e.m.c.- impedance measurements on single crystals (25 °C) show that Li+ diffusion in LixV6O13 is one dimensional and proceeds along the channels in the b axis direction.
TL;DR: In this article, high-pressure X-ray diffraction studies have been performed on cerium powder up to 46 GPa using a diamond anvil cell and synchrotron radiation.
Abstract: High-pressure X-ray diffraction studies have been performed on cerium powder up to 46 GPa using a diamond anvil cell and synchrotron radiation. The results confirm the following transitions: γ(fcc)−α(fcc) at 0.8 GPa, α(fcc)−α″ (monoclinic b.c.) at 5 GPa and α″ (monoclinic bc)-tetragonal bc at 12 GPa. All high-pressure structures can be described as distorted fcc. No clear evidence has been found for the α'-phase with α-uranium structure. It is found that the bulk modulus is 21 GPa for γ-Ce and 20 GPa for the combined compression data of α−Ce, α″-Ce and tetragonal Ce in good agreement with other experimental and theoretical data. The experimental V(P) data are compared with a theoretical equation of state obtained by the linear muffin-tin method.
TL;DR: The experimental radiation effectiveness (RE) with reference to low-LET radiations of60 Co γ rays, 4 and 16 MV X rays, and 6, 10, and 20 MeV electrons was compared with theoretical RE values derived from a model based on track structure theory of heavy charged particles.
Abstract: Dose-response characteristics have been measured for the crystalline amino acid L-α-alanine irradiated with ion beams of 6 and 16 MeV protons, 20 MeV α particles, 21 MeV ${}^{7}{\rm Li}$ ions, 64 MeV16 O ions, and 80 MeV ${}^{32}{\rm S}$ ions. The experimental radiation effectiveness (RE) with reference to low-LET radiations of60 Co γ rays, 4 and 16 MV X rays, and 6, 10, and 20 MeV electrons was compared with theoretical RE values derived from a model based on track structure theory of heavy charged particles. The ion beams covered a range in initial LET of $27-20,200\ {\rm MeVcm}^{2}/{\rm g}$ , and the experimental RE decreased with increasing LET being 1.00 for 16 MeV protons and 0.25 for the 80 MeV ${}^{32}{\rm S}$ ions. The calculated Re values were in acceptable agreement with the experimental results having a maximum deviation of 8% for the ${}^{7}{\rm Li}$ and ${}^{32}{\rm S}$
TL;DR: This paper reviews the present process technology for biological phosphorus (P) removal, the fundamental biological and chemical P removal mechanisms, analytical characterization methods for biological and inorganic P fractions, and finally conventional and new techniques for process design.
Abstract: This paper reviews the present process technology for biological phosphorus (P) removal, the fundamental biological and chemical P removal mechanisms, analytical characterization methods for biological and inorganic P fractions, and finally conventional and new techniques for process design. The understanding of enhanced biological P removal has improved significantly in the past few years. Polyphosphate (poly‐P) accumulating bacteria appear to be selected by introducing an anaerobic fermentation reactor in which the biomass has access to readily biodegradable organics, like volatile acids, etc. The poly‐P bacteria are able to use poly‐P as an energy reserve to absorb and store the readily biodegradable organics, e.g., as s‐polyhy‐droxybutyrate. This gives them an advantage over nonpoly‐P bacteria in their competition for substrate. In some biological P‐removal plants, phosphate precipitation by cations in the sewage may play a significant role. A few milligrams per liter of iron and/or aluminum in the wa...
TL;DR: The infrared principal axes of superconducting β-(BEDT-TTF)2I3 are found to be directed along the chain axis and perpendicular to the axis in the a-b plane as mentioned in this paper.
TL;DR: Inulin and d-fructose are quantitatively converted into a mixture of d -fructose dianhydrides on treatment with anhydrous hydrogen fluoride as discussed by the authors, and the structures of two of the known dianhides have been revised.
TL;DR: It is shown that a linear two-dimensional cyclic code of length nN can be factorized into a direct sum of concatenated codes, with cyclic inner and outer codes, and it appears that the Abelian codes are obtainable by taking adirect sum of several concatenations of cyclic codes.
Abstract: It is shown that a linear two-dimensional cyclic code of length nN can be factorized into a direct sum of concatenated codes, with cyclic inner and outer codes and, conversely, thai a two-dimensional cyclic code can be constructed in this way This result is extended, and it appears that the Abelian codes are obtainable by taking a direct sum of several concatenations of cyclic codes Codes are constructed that are better than any previously known In particular, low-rate cyclic codes superior to the duals of high-rate BCH codes are constructed
TL;DR: The stripping of phosphorus, potassium and magnesium, and uptake of organic substrate and calcium was studied in the anaerobic reactors of two biological phosphorus and nitrogen removal plants, and phosphate appears to be precipitated simultaneously with the biological P-stripping.
TL;DR: In this article, the influence of tensile stress annealing on the magnetic properties of amorphous alloys is reported for ribbons belonging to the pseudo ternary system (FeCoNi) 75 Si 15 B 10.
Abstract: The influence of tensile stress annealing on the magnetic properties of amorphous alloys is reported for ribbons belonging to the pseudo ternary system (FeCoNi) 75 Si 15 B 10 . Ribbons of compositions (Co 1-x Fe x ) 75 Si 15 B 10 are susceptible to stress annealing in the whole composition range 0 \leq x \leq 1 . A very large easy ribbon axis anisotromy can be produced in the range 0.2 \leq x \leq 0.7 whereas the largest hard ribbon axis anisotropy is producable in the composition range around x=0.15. Ribbons of compositions [CO 1-x (Fe 0.5 Ni 0.5 ) x ] 75 Si 15 B 10 are found susceptible to stress annealing only in the range 0 \leq x \leq 0.7 . In all the compositions the induced easy ribbon axis anisotropies are irreversible whereas the hard ribbon axis anisotropies are recoverable with activation energies ≥ 1.55 eV.
TL;DR: In this paper, the production of very large transverse momentum (p T ) hadron jets has been measured in the UA2 experiment at the CERN p p Collider for s =630 GeV.
TL;DR: In this paper, an expression for the FM noise spectrum of an injection-locked semiconductor laser was derived and the ultimate linewidth reduction was obtained if the locking bandwidth is large enough to accommodate the frequency fluctuations and if the detuning is controlled carefully.
Abstract: An expression is derived for the FM noise spectrum of an injection-locked semiconductor laser. For increasing injection level the FM noise spectrum and the lineshape change gradually from those of the slave laser to those of the master laser. The ultimate linewidth reduction is obtained if the locking bandwidth is large enough to accommodate the frequency fluctuations and if the detuning is controlled carefully.
TL;DR: In this article, double layer dynamics are investigated in a Q-machine plasma by applying a positive step potential to a cold end-plate collector, where the double layer created at the grounded plasma source just after the pulse is applied propagates towards the collector with the plasma flow speed.
Abstract: Investigations of double layer dynamics are performed in a Q-machine plasma by applying a positive step potential to a cold end-plate collector. The double layer created at the grounded plasma source just after the pulse is applied propagates towards the collector with the plasma flow speed. Large oscillations occur in the plasma current which is related to a recurring formation and propagation of the double layer. The current is limited during the propagation by a growing negative potential dip formed on the low-potential tail. Similar phenomena appear on the low-potential tail of the stationary double layer formed by applying a potential difference between two plasma sources.
TL;DR: In this article, a systematic evaluation of the parameters affecting the measurement of pH in a flow injection system incorporating a tubular PVC-based pH-sensitive membrane electrode is presented in order to obtain reliable results, it is necessary to have a dispersion coefficient Dmax ⩽ 1008 at peak maximum and to adjust the buffering capacity of the carrier stream to be less than the sample solution.
TL;DR: In this article, the rate limiting substrate and half-order rate constants were identified on the basis of biofilm kinetics for triple substrate conditions (organic matter, ammonia and oxygen) in a rotating biological disc system.