1,188 research outputs found
The etymology of Modern English monkey
Modern English monkey does not represent a Romance loan-word of Arabian origin and transmitted
by Middle Low German but is a vernacular diminutive derived from monk
P-polarized reflectance spectroscopy: A high sensitive real-time monitoring technique to study surface kinetics under steady state epitaxial deposition conditions
This paper describes the results of real-time optical monitoring of epitaxial growth processes by p-polarized reflectance spectroscopy (PRS) using a single wavelength application under pulsed chemical beam epitaxy (PCBE) condition. The high surface sensitivity of PRS allows the monitoring of submonolayer precursors coverage on the surface as shown for GaP homoepitaxy and GaP on Si heteroepitaxy as examples. In the case of heteroepitaxy, the growth rate and optical properties are revealed by PRS using interference oscillations as they occur during growth. Super-imposed on these interference oscillations, the PRS signal exhibits a fine structure caused by the periodic alteration of the surface chemistry by the pulsed supply of chemical precursors. This fine structure is modeled under conditions where the surface chemistry cycles between phosphorus supersaturated and phosphorus depleted surfaces. The mathematical model describes the fine structure using a surface layer that increases during the tertiarybutyl phosphine (TBP) supply and decreases during and after the triethylgallium (TEG) pulse, which increases the growing GaP film thickness. The imaginary part of the dielectric function of the surface layer is revealed from the turning points in the fine structure, where the optical response to the first precursor pulse in the cycle sequence changes sign. The amplitude of the fine structure is determined by the surface layer thickness and the complex dielectric functions for the surface layer with the underlying bulk film. Surface kinetic data can be obtained by analyzing the rise and decay transients of the fine structure
Relationship between the entomologic inoculation rate and the force of infection for Plasmodium falciparum malaria.
We propose a stochastic model for the relationship between the entomologic inoculation rate (EIR) for Plasmodium falciparum malaria and the force of infection in endemic areas. The model incorporates effects of increased exposure to mosquito bites as a result of the growth in body surface area with the age of the host, naturally acquired pre-erythrocytic immunity, and the reduction in the proportion of entomologically assessed inoculations leading to infection, as the EIR increases. It is fitted to multiple datasets from field studies of the relationship between malaria infection and the EIR. We propose that this model can account for non-monotonic relationships between the age of the host and the parasite prevalence and incidence of disease. It provides a parsimonious explanation for the faster acquisition of natural immunity in adults than in children exposed to high EIRs. This forms one component of a new stochastic model for the entire transmission cycle of P. falciparum that we have derived to estimate the potential epidemiologic impact of malaria vaccines and other malaria control interventions
[4-(Di-tert-butylÂfluoroÂsilanÂyl)phenyl]methanol
The asymmetric unit of the title compound, C15H25FOSi, contains two independent molÂecules. Each of the Si atoms approximates the expected tetraÂhedral geometry with Si—F bond lengths of 1.6128 (11) and 1.6068 (11) Å in the two independent molÂecules. In the crystal, supraÂmolecular chains along a are found mediated by O—H⋯O hydrogen bonds
A model for natural immunity to asexual blood stages of Plasmodium falciparum malaria in endemic areas.
Most mathematical models for acquired immunity to Plasmodium falciparum consider effects of immunity on duration of infection and infectiousness, but do not consider the most evident effect of immunity, which is to reduce parasite densities. Few attempts have been made to fit such models to field data. We propose a stochastic simulation model to predict the distributions of P. falciparum parasite densities in endemic areas, in which acquired immunity acts by reducing parasite densities. We have fitted this model to age-specific prevalence and geometric mean densities from settings in Ghana, Nigeria, and Tanzania. The model appears to reproduce reasonably well the parasitologic patterns seen in malariologic surveys in endemic areas and is appropriate for predicting the impact of interventions such as vaccination in the context of continual exposure to P. falciparum
Design of a Cooper pair box electrometer for application to solid-state and astroparticle physics
We describe the design and principle of operation of a fast and sensitive
electrometer operated at millikelvin temperatures, which aims at replacing
conventional semiconducting charge amplifiers in experiments needing low
back-action or high sensitivity. The electrometer consists of a Cooper Pair box
(CPB) coupled to a microwave resonator, which converts charge variations to
resonance frequency shifts. We analyze the dependence of the sensitivity on the
various parameters of the device, and derive their optimization. By exploiting
the nonlinearities of this electrometer, and using conventional nanofabrication
and measurement techniques, a charge sensitivity of a few can be achieved which outperforms existing single charge
electrometers.Comment: 13 pages, 7 figure
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