3,119 research outputs found
On Topological Chaos in the Robinson-Solow-Srinivasan Model
No full textIn this paper, we offer an instance of (topologically) chaotic optimal behavior in a twosector model with irreversible investment, originally formulated by Robinson, Solow and Srinivasan. Our result follows from the theory of turbulence in non-linear dynamical systems, and relies only on the existence of a continuous optimal policy function. The fact that there is a unique optimal program from each initial stock when future utilities are discounted by a factor smaller than the labor-capital ratio may be of independent interest.
Absolute Absorption and Dispersion in a Thermal Rb Vapour at High Densities and High Magnetic Fields.
No full textThis thesis presents a comparative study of the measured and calculated absolute absorption and dispersion properties of the Rb D lines through a dense thermal vapour in the absence and presence of an applied magnetic field. A detailed theoretical model valid in the weak-probe regime is calculated. The model uses a matrix representation of the atomic Hamiltonian including the magnetic field interaction for Rb in the completely uncoupled basis. Numerical diagonalisation allows the frequency detunings and transition strengths to be calculated. The lineshape of each transition is modelled as a Voigt profile, a convolution of the inhomogeneous and homogeneous profiles. The medium’s susceptibility is found by summing over all the electric-dipole-allowed transitions. For dense thermal vapours a modification to the homogeneous linewidth of each transition, which grows linearly with the number density of atoms, arises due to resonant dipole-dipole interactions between identical atoms in superpositions of the ground and excited terms. In the presence of an applied magnetic field we investigate the Stokes parameters of light propagating through a dense thermal vapour. For fields larger than 0.33 T we enter the hyperfine Paschen-Back regime on the Rb D lines. We present a compact optical isolator based on an atomic vapour, exploiting the spectral region of high transmission and large dispersion where we would normally expect absorption on the Rb D lines. Frequency up-conversion is shown in the fluorescence measurements over the visible and near infra-red regions for strong excitation. Low density transfer arises due to the energy-pooling effect between two identical atoms in their first excited terms. At
high densities resonant dipole-dipole interactions give rise to a threshold for the energy transfer. We characterise the threshold behaviour with increasing number density
At physiologic albumin:oleate concentrations oleate uptake by isolated hepatocytes, adipocytes and cardiac myocytes is a saturable function of unbound oleate concentrations. Uptake kinetics are consistent with the conventional theory
No full textTo reexamine the role of albumin in cellular uptake of long chain fatty acids, we measured [3H]oleate uptake by isolated hepatocytes, adipocytes, and cardiac myocytes from incubations containing oleate/albumin complexes at molar ratios from 0.01:1 to 2:1. For each ratio the uptake was studied over a wide range of albumin concentrations. In all three cell types and at any given oleate/albumin ratio, the uptake appeared saturable with increasing concentrations of oleate:albumin complexes despite the fact that the unbound oleate concentration for each molar ratio is essentially constant. However, the 'K(m)' but not the 8V(max)' of these pseudosaturation curves was influenced by substrate availability. At low albumin concentrations, uptake velocities did not correlate with unbound oleate concentrations. However, observed and expected uptake velocities coincided at albumin concentrations approaching physiologic levels and were a saturable function of the oleate/albumin ratios and the consequent unbound oleate concentrations employed. Hence, under the experimental conditions employed in this study using a variety of suspended cell types, oleate uptake kinetics were consistent with the conventional theory at physiologic concentrations of albumin
Education groups for those with painful peripheral diabetic neuropathy an evaluation
No full textPainful peripheral diabetic neuropathy (PPDN) can dominate people’s lives. In 1990 the St Vincent Declaration admirably aimed to halve amputation rates due to diabetic gangrene (World Health Organisation [Europe] and International Diabetes Federation [Europe], 1990). The incidence of lower limb amputations in people with diabetes has been reported as 248 per 100 000 patient years, compared with 20 per 100 000 patient years for those without diabetes (Morris et al, 1998). It is well known that the downward slide towards amputation often begins with peripheral neuropathy (Boulton et al, 2000). This article discusses group education sessions used to inform both the person with PPDN and the healthcare professional
Liquid structure of Rb-Hg alloys studied by neutron diffraction
No full textThe structures of liquid Rb–Hg alloys were studied as a function of composition by neutron diffraction. In the intermediate Rb concentration range, the obtained structure factors show a small prepeak, which may be an evidence of the formation of Hg polyanion units in liquids. The Reverse Monte Carlo (RMC) analysis was applied to separate the total radial distribution function into the corresponding partial radial distribution functions. Up to 10 at.% Rb, no obvious changes are found for the first peak position of the partial radial distribution functions of the Hg–Hg pair and that of the Hg–Rb pair. The first peak position between the Hg–Rb pairs increases above 20 at.% Rb. In addition to the first peak, a subpeak between Hg–Hg pairs can be seen in the large distance. At 60 at.% Rb, the nearest neighbor distance between Hg atoms shows the closest value in the concentration range studied. These results indicate that with the progress of charge transfer the solvation structure in the dilute Rb concentration range changes into the structure containing polyanions composed of Hg species
Shotgun proteomic analysis of Chlamydia trachomatis
No full textChlamydiae are widespread bacterial pathogens responsible for a broad range of diseases, including sexually transmitted infections, pneumonia and trachoma. To validate the existence of hitherto hypothetical proteins predicted from recent chlamydial genome sequencing projects and to examine the patterns of expression of key components at the protein level, we have surveyed the expressed proteome of Chlamydia trachomatis strain L2. A combination of two-dimensional gel analysis, multi-dimensional protein identification (MudPIT) and nanocapillary liquid chromatography-tandem mass spectrometry allowed a total of 328 chlamydial proteins to be unambiguously assigned. Proteins identified as being expressed in the metabolically inert form, elementary body, of Chlamydia include the entire set of predicted glycolytic enzymes, indicating that metabolite flux rather than de novo synthesis of this pathway is triggered upon infection of host cells. An enzyme central to cell wall biosynthesis was also detected in the intracellular form, reticulate body, of Chlamydia, suggesting that the peptidoglycan is produced during growth within host cells. Other sets of proteins identified include 17 outer membrane-associated proteins of potential significance in vaccine studies and 67 proteins previously annotated as hypothetical or conserved hypothetical. Taken together, ?35% of the predicted proteome for C. trachomatis has been experimentally verified, representing the most extensive survey of any chlamydial proteome to date
La Tijâniyya. Une confrérie musulmane à la conquête de l'Afrique, sous la direction de Jean-Louis De Triaud et David Robinson
No full textLa Tijâniyya. Une confrérie musulmane à la conquête de l'Afrique, sous la direction de Jean-Louis De Triaud et David Robinson, Paris, Karthala, 2000. Confrérie souvent controversée, la Tijâniyya a été fondée en l'année 1195 de l'Hégire (1781-1782 de notre ère), à la suite d'une vision du Prophète, dans l'oasis algérienne d'Abû Samghun, par le savant et mystique Ahmad al-Tijânî (1737-1815). Depuis cette date, la Tijâniyya s'est imposée comme la grande confrérie africaine des XIXe et XXe siècle..
Fractional Edge Cover Number of Model RB
No full textModel RB is a random constraint satisfaction problem with a growing domain size, which exhibits exact phase transition phenomena. Many hard instances with planted solutions can be generated via Model RB, to be used as benchmarks for algorithmic competitions and researches. In the past, some structural parameters of constraint hypergraphs are analyzed to show hardness of Model RB, such as hinge width, decycling number, treewidth, and hypertree width. In this paper, one more structural parameter of constraint hypergraphs of Model RB, namely the fractional edge cover number, is analyzed. We show upper and lower bounds on the fractional edge cover number of Model RB. In particular, the fractional edge cover number of Model RB is shown to be asymptotically linear in the number of variables, like hinge width, decycling number, treewidth and hypertree width. These results together provide further evidences on the hardness of Model RB.EICPCI-S(ISTP)[email protected]
WSO907003 Supplemental material - Supplemental material for INFOMATAS multi-center systematic review and meta-analysis individual patient data of dynamic cerebral autoregulation in ischemic stroke
No full textSupplemental material, WSO907003 Supplemental material for INFOMATAS multi-center systematic review and meta-analysis individual patient data of dynamic cerebral autoregulation in ischemic stroke by L Beishon, JS Minhas, R Nogueira, P Castro, C Budgeon, M Aries, S Payne, TG Robinson and RB Panerai in International Journal of Stroke</p
Epidemiology of human sapporo-like caliciviruses in the South West of England: molecular characterisation of a genetically distinct isolate
No full textHuman enteric caliciviruses have been assigned to two distinct genera: the Norwalk-like viruses (NLVs) and the Sapporo-like viruses (SLVs). During a 3-year surveillance of gastroenteritis in the South West of England during November 1997-2000, a total of 27 clinical samples containing SLVs were collected. PCR amplicons covering a region of the RNA polymerase gene were obtained from 18 of the SLV samples. Sequence analysis of the PCR products indicated that the SLV isolates could be assigned to one of the two major genetic groups represented by Sapporo and London/92 caliciviruses. One of these isolates belonging to the London/92 group (Bristol/98) was subjected to a complete genome sequence analysis. The full genomic sequence of the Bristol/98 isolate was determined from RNA extracted from a single stool sample and consists of 7490 nucleotides, excluding the poly(A) tail. The genome is organised into two open reading frames (ORFs), similar to that of Manchester SLV although the small ORF overlapping the region encoding the capsid protein observed in Manchester SLV is absent in Bristol/98 SLV. The polyprotein (ORF1) of Bristol/98 SLV consists of 2,280 amino acids and, as observed in all SLVs, the structural protein is encoded in frame and contiguous with the 3' terminus of the ORF1. Phylogenetic studies based on complete capsid sequences and genome arrangements within the SLVs indicate that the human enteric viruses within the "Sapporo-like" virus clade should be divided into two distinct genetic groups analogous to the assignment of the Norwalk-like viruses
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