2,393 research outputs found
Average transmission probability of a random stack
The transmission through a stack of identical slabs that are separated by
gaps with random widths is usually treated by calculating the average of the
logarithm of the transmission probability. We show how to calculate the average
of the transmission probability itself with the aid of a recurrence relation
and derive analytical upper and lower bounds. The upper bound, when used as an
approximation for the transmission probability, is unreasonably good and we
conjecture that it is asymptotically exact.Comment: 10 pages, 6 figure
Electromagnetic Energy, Momentum, and Angular Momentum in an Inhomogeneous Linear Dielectric
In a previous work, Optics Communications 284 (2011) 2460--2465, we
considered a dielectric medium with an anti-reflection coating and a spatially
uniform index of refraction illuminated at normal incidence by a
quasimonochromatic field. Using the continuity equations for the
electromagnetic energy density and the Gordon momentum density, we constructed
a traceless, symmetric energy--momentum tensor for the closed system. In this
work, we relax the condition of a uniform index of refraction and consider a
dielectric medium with a spatially varying index of refraction that is
independent of time, which essentially represents a mechanically rigid
dielectric medium due to external constraints. Using continuity equations for
energy density and for Gordon momentum density, we construct a symmetric
energy--momentum matrix, whose four-divergence is equal to a generalized
Helmholtz force density four-vector. Assuming that the energy-momentum matrix
has tensor transformation properties under a symmetry group of space-time
coordinate transformations, we derive the global conservation laws for the
total energy, momentum, and angular momentum.Comment: added publication informatio
Ideals of womanhood in the literature of Finland and Russia 1894-1914
This study is a literary critical examination of the portrayal of woman in
prose and drama, with reference to the themes of political and artistic
rebirth which preoccupied writers in Finland and Russia at the turn of
the century.
The study falls into three sections, each of which represents an
aspect of woman's metaphysical condition and for which I have used the
categories Action, Voice,a nd Visibility. The first section assesses writers'
approach to the issues raised by the woman question, and describes the
cultivation of an ideal of politically active, nationally loyal womanhood
in the image of the Madonna. The second section demonstrates that
woman's silence, a dominant feature of her characterization, signifies
both the danger of revolution and the prescription for her social
integration. It also includes an analysis of the opportunities and
consequences of self-expression for female characters and writers. The
third section deals with the view of woman as an embodiment of artistic
impulse, especially her idealization as muse, and addresses the issue of
pornography in the representation of the female form.
The comparison between the two literatures explores the
respective national ambitions as well as the concept of the 'new
woman'. The image of woman is influenced by contemporary theory of
her nature and social function. The literatures contrast most notably in
the relationship of the Madonna-like saviour to the political hero, and
of the muse to the artist. In Russia, the historic mission of nation and
artist is imbued with universal and eternal significance. In Finland, it
relates to the immediate, localized ambitions of national selfdetermination.
Woman is shown to have a central place in both
countries in the process of political and artistic renewal. However, the
ideal of womanhood plays upon preconceptions of femininity which
preclude the notion of woman's equality and independence at the root
of feminist thought. The limitations on woman's existence are
observable in the elements of silence and pornography which affect her
characterization, erasing her subjective identity and promoting her
objectification
Tunable two-dimensional plasmon resonances in an InGaAs/InP high electron mobility transistor
Voltage-tunable plasmon resonances in the two-dimensional electron gas (2DEG) of a high electron mobility transistor (HEMT) fabricated from the InGaAs/InP materials system are reported. The device was fabricated from a commercial HEMT wafer by depositing source and drain contacts using standard photolithography and a semitransparent gate contact that consisted of a 0.5 mu m period transmission grating formed by electron-beam lithography. Narrow-band resonant absorption of terahertz radiation was observed in transmission in the frequency range of 10-50 cm(-1). The resonance frequency depends on the gate-tuned sheet charge density of the 2DEG. The observed separation of resonance fundamental from its harmonics and their shift with gate bias are compared with theory
Oxygen isotopic composition of nitrate and nitrite produced by nitrifying cocultures and natural marine assemblages
Author Posting. © Association for the Sciences of Limnology and Oceanography, 2012. This article is posted here by permission of Association for the Sciences of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 57 (2012): 1361-1375, doi:10.4319/lo.2012.57.5.1361.The δ18O value of nitrate produced during nitrification (δ18ONO3,nit) was measured in experiments designed to mimic oceanic conditions, involving cocultures of ammonia-oxidizing bacteria or ammonia-oxidizing archaea and nitrite-oxidizing bacteria, as well as natural marine assemblages. The estimates of ranged from −1.5‰ ± 0.1‰ to +1.3‰ ± 1.4‰ at δ18O values of water (H2O) and dissolved oxygen (O2) of 0‰ and 24.2‰ vs. Vienna Standard Mean Ocean Water, respectively. Additions of 18O-enriched H2O allowed us to evaluate the effects of oxygen (O) isotope fractionation and exchange on . Kinetic isotope effects for the incorporation of O atoms were the most important factors for setting overall values relative to the substrates (O2 and H2O). These isotope effects ranged from +10‰ to +22‰ for ammonia oxidation (O2 plus H2O incorporation) and from +1‰ to +27‰ for incorporation of H2O during nitrite oxidation. values were also affected by the amount and duration of nitrite accumulation, which permitted abiotic O atom exchange between nitrite and H2O. Coculture incubations where ammonia oxidation and nitrite oxidation were tightly coupled showed low levels of nitrite accumulation and exchange (3% ± 4%). These experiments had values of −1.5‰ to +0.7‰. Field experiments had greater accumulation of nitrite and a higher amount of exchange (22% to 100%), yielding an average value of +1.9‰ ± 3.0‰. Low levels of biologically catalyzed exchange in coculture experiments may be representative of nitrification in much of the ocean where nitrite accumulation is low. Abiotic oxygen isotope exchange may be important where nitrite does accumulate, such as oceanic primary and secondary nitrite maxima.This research was funded by the National Science
Foundation Chemical Oceanography grants 05-26277 and 09-
610998 to K.L.C
Nitrogen cycling in the secondary nitrite maximum of the eastern tropical North Pacific off Costa Rica
Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 29 (2015): 2061–2081, doi:10.1002/2015GB005187.Nitrite is a central intermediate in the marine nitrogen cycle and represents a critical juncture where nitrogen can be reduced to the less bioavailable N2 gas or oxidized to nitrate and retained in a more bioavailable form. We present an analysis of rates of microbial nitrogen transformations in the oxygen deficient zone (ODZ) within the eastern tropical North Pacific Ocean (ETNP). We determined rates using a novel one-dimensional model using the distribution of nitrite and nitrate concentrations, along with their natural abundance nitrogen (N) and oxygen (O) isotope profiles. We predict rate profiles for nitrate reduction, nitrite reduction, and nitrite oxidation throughout the ODZ, as well as the contributions of anammox to nitrite reduction and nitrite oxidation. Nitrate reduction occurs at a maximum rate of 25 nM d−1 at the top of the ODZ, at the same depth as the maximum rate of nitrite reduction, 15 nM d−1. Nitrite oxidation occurs at maximum rates of 10 nM d−1 above the secondary nitrite maximum, but also in the secondary nitrite maximum, within the ODZ. Anammox contributes to nitrite oxidation within the ODZ but cannot account for all of it. Nitrite oxidation within the ODZ that is not through anammox is also supported by microbial gene abundance profiles. Our results suggest the presence of nitrite oxidation within the ETNP ODZ, with implications for the distribution and physiology of marine nitrite-oxidizing bacteria, and for total nitrogen loss in the largest marine ODZ.National Science Foundation. Grant Numbers OCE 05-26277, OCE 09-610998; WHOI Coastal Ocean Institute2016-06-1
Search for Magnetic Monopoles Trapped in Matter
There have been many searches for magnetic monopoles in flight, but few for
monopoles in matter. We have searched for magnetic monopoles in meteorites,
schists, ferromanganese nodules, iron ores and other materials. The detector
was a superconducting induction coil connected to a SQUID (Superconducting
Quantum Interference Device) with a room temperature bore 15 cm in diameter. We
tested a total of more than 331 kg of material including 112 kg of meteorites.
We found no monopole and conclude the overall monopole/nucleon ratio in the
samples is with a 90\% confidence level.Comment: 6 pages, rev tex, no figure
Stapling and Section of the Nasogastric Tube during Sleeve Gastrectomy: How to Prevent and Recover?
Bariatric surgery has become an integral part of morbid obesity treatment with well-defined indications. Some complications, specific or not, due to laparoscopic sleeve gastrectomy (LSG) procedure have recently been described. We report a rare complication unpublished to date: a nasogastric section during great gastric curve stapling. A 44-year-old woman suffered of severe obesity (BMI 36.6 kg/m2) with failure of medical treatments for years. According to already published technique, a LSG was performed. Six hours postoperatively, a nurse removed the nasogastric tube according to the local protocol and the nasogastric tube was abnormally short, with staples at its extremity. Surgery was performed with peroperative endoscopy. In conclusion, this is the first publication of a nasogastric section during LSG. Therefore we report this case and propose a solution to prevent its occurrence. To avoid this kind of accident, we now systematically insert the nasogastric tube by mouth through a Guedel cannula. Then, to insert the calibrating bougie, we entirely withdraw the nasogastric tube
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