626 research outputs found
Testing Revisionist Toolkits: Russia in Kyrgyzstan
It is now commonplace in the West to describe Russia as a revisionist power, seeking to change the international system and regain its status as a great power. This perception became more popular after 2008 in Georgia but only truly solidified after Russian interventions in Crimea and Syria. Russia, however, did not act on its revisionist tendencies overnight. What were the mechanisms that allowed Russia to become revisionist, and how did it test these mechanisms? This paper argues that Russia’s revisionism started earlier than many claim – in Kyrgyzstan and Central Asia more broadly in the early 2000’s. In overlooking these earlier historical developments, we risk misunderstanding Russian revisionist tendencies, the roots of which stem back to the ‘Colour Revolutions’ in Georgia, in Ukraine, and in Kyrgyzstan. In examining Russian revisionism, most scholars concentrate on the first two, but this focus only tells part of the story. While this paper does not try to understand the relative success or failure of Russian actions in these countries, it does demonstrate that Kyrgyzstan was in many ways a testing ground for Russia as it developed its revisionist toolkit. Through analysing Russian efforts to reduce U.S. influence in Central Asia in the early 2000s, this paper helps us to better understand how Russia developed techniques used in Georgia and Crimea, how Russia conceptualized their own abilities to intervene in other countries, and ultimately how Russia conceives of its ability to revise the international system with minimal external response
Lessons learned from the development and manufacture of ceramic reusable surface insulation materials for the space shuttle orbiters
Three ceramic, reusable surface insulation materials and two borosilicate glass coatings were used in the fabrication of tiles for the Space Shuttle orbiters. Approximately 77,000 tiles were made from these materials for the first three orbiters, Columbia, Challenger, and Discovery. Lessons learned in the development, scale up to production and manufacturing phases of these materials will benefit future production of ceramic reusable surface insulation materials. Processing of raw materials into tile blanks and coating slurries; programming and machining of tiles using numerical controlled milling machines; preparing and spraying tiles with the two coatings; and controlling material shrinkage during the high temperature (2100-2275 F) coating glazing cycles are among the topics discussed
Statistics of soliton-bearing systems with additive noise
We present a consistent method to calculate the probability distribution of
soliton parameters in systems with additive noise. Even though a weak noise is
considered, we are interested in probabilities of large fluctuations (generally
non-Gaussian) which are beyond perturbation theory. Our method is a further
development of the instanton formalism (method of optimal fluctuation) based on
a saddle-point approximation in the path integral. We first solve a fundamental
problem of soliton statistics governing by noisy Nonlinear Schr\"odinger
Equation (NSE). We then apply our method to optical soliton transmission
systems using signal control elements (filters, amplitude and phase
modulators).Comment: 4 pages. Submitted to PR
Loss of murine Paneth cell function alters the immature intestinal microbiome and mimics changes seen in neonatal necrotizing enterocolitis
Necrotizing enterocolitis (NEC) remains the leading cause of gastrointestinal morbidity and mortality in premature infants. Human and animal studies suggest a role for Paneth cells in NEC pathogenesis. Paneth cells play critical roles in host-microbial interactions and epithelial homeostasis. The ramifications of eliminating Paneth cell function on the immature host-microbial axis remains incomplete. Paneth cell function was depleted in the immature murine intestine using chemical and genetic models, which resulted in intestinal injury consistent with NEC. Paneth cell depletion was confirmed using histology, electron microscopy, flow cytometry, and real time RT-PCR. Cecal samples were analyzed at various time points to determine the effects of Paneth cell depletion with and without Klebsiella gavage on the microbiome. Deficient Paneth cell function induced significant compositional changes in the cecal microbiome with a significant increase in Enterobacteriacae species. Further, the bloom of Enterobacteriaceae species that occurs is phenotypically similar to what is seen in human NEC. This further strengthens our understanding of the importance of Paneth cells to intestinal homeostasis in the immature intestine
Preliminary Heat Capacity and Vapor Pressure Measurements of 2D 4He on ZYX Graphite
We report preliminary heat capacity and vapor pressure measurements of the
first and second layers of 4He adsorbed on ZYX graphite. ZYX is known to have
much better crystallinity than Grafoil, the most commonly-used exfoliated
graphite substrate, such as a ten-times larger platelet size. This allows us to
distinguish different phases in 2D helium-4 much more clearly and may provide
qualitatively different insights into this system. We found a significantly
asymmetric density-dependence of the heat-capacity peak associated with the 1/3
phase formation comparing with that obtained with Grafoil. The 2nd-layer
promotion density is determined as 11.8+-0.3 nm-2 from the heat-capacity
measurement of low density samples in the 2nd layer and vapor pressure
measurement.Comment: 7 pages, 7 figures, accepted for publication in JLTP - QFS201
Influence of invasive quagga mussels, phosphorus loads, and climate on spatial and temporal patterns of productivity in Lake Michigan: A biophysical modeling study
We applied a three‐dimensional biophysical model to Lake Michigan for the years 2000, 2005, and 2010 to consider the mechanisms controlling spatial and temporal patterns of phytoplankton abundance (chlorophyll a) and lake‐wide productivity. Model skill was assessed by comparison to satellite‐derived Chl a and field‐measured water quality variables. We evaluated model sensitivity to scenarios of varying mussel filter feeding intensity, tributary phosphorus loads, and warm vs. cool winter‐spring climate scenarios. During the winter‐spring phytoplankton bloom, spatial patterns of Chl a were controlled by variables that influenced surface mixed layer depth: deep mixing reduced net phytoplankton growth through light limitation and by exposing the full water column to mussel filter feeding. Onset of summer and winter stratification promoted higher surface Chl a initially by increasing mean light exposure and by separating the euphotic zone from mussels. During the summer stratified period, areas of relatively high Chl a were associated with coastal plumes influenced by tributary‐derived nutrients and coastal upwelling‐downwelling. While mussels influenced spatial and temporal distribution of Chl a, lake‐wide, annual mean primary production was more sensitive to phosphorus and warm/cool meteorology scenarios than to mussel filter feeding scenarios. Although Chl a and primary production declined over the quagga mussel invasion, our results suggest that increased nutrient loads would increase lake‐wide productivity even in the presence of mussels; however, altered spatial and temporal patterns of productivity caused by mussel filter feeding would likely persist.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139984/1/lno10595-sup-0001-suppinfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139984/2/lno10595.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139984/3/lno10595_am.pd
The Changing Face of Winter: Lessons and Questions From the Laurentian Great Lakes
Among its many impacts, climate warming is leading to increasing winter air temperatures, decreasing ice cover extent, and changing winter precipitation patterns over the Laurentian Great Lakes and their watershed. Understanding and predicting the consequences of these changes is impeded by a shortage of winter-period studies on most aspects of Great Lake limnology. In this review, we summarize what is known about the Great Lakes during their 3–6 months of winter and identify key open questions about the physics, chemistry, and biology of the Laurentian Great Lakes and other large, seasonally frozen lakes. Existing studies show that winter conditions have important effects on physical, biogeochemical, and biological processes, not only during winter but in subsequent seasons as well. Ice cover, the extent of which fluctuates dramatically among years and the five lakes, emerges as a key variable that controls many aspects of the functioning of the Great Lakes ecosystem. Studies on the properties and formation of Great Lakes ice, its effect on vertical and horizontal mixing, light conditions, and biota, along with winter measurements of fundamental state and rate parameters in the lakes and their watersheds are needed to close the winter knowledge gap. Overcoming the formidable logistical challenges of winter research on these large and dynamic ecosystems may require investment in new, specialized research infrastructure. Perhaps more importantly, it will demand broader recognition of the value of such work and collaboration between physicists, geochemists, and biologists working on the world\u27s seasonally freezing lakes and seas
Non-Gaussian statistics of an optical soliton in the presence of amplified spontaneous emission
A study was performed on non-Gaussian statistics of an optical soliton in the presence of amplified spontaneous emission. An approach based on the Fokker-Planck equation was applied to study the optical soliton parameters in the presence of additive noise. The rigorous method not only allowed to reproduce and justify the classical Gordon-Haus formula but also led to new exact results
Uptake and Retention of Nanoplastics in Quagga Mussels
Here, a set of experiments to assess the feasibility of using an invasive and widespread freshwater mussel (Dreissena rostrformis bugensis) as a sentinel species for nanoplastic detection is reported. Under laboratory experimental conditions, mussels ingest and retain fluorescent polystyrene (PS) beads with carboxylic acid (COOH) termination over a size range of 200- 2000 nm. The number of beads the mussels ingested is quantified using fluorescence spectroscopy and the location of the beads in the mussels is imaged using fluorescence microscopy. PS beads of similar size (1000- 2000 nm) to mussels’ preferred food are trafficked in the ciliated food grooves of the gills. Beads of all sizes are observed in the mussels’ digestive tracts, indicating that the mussels do not efficiently reject the beads as unwanted foreign material, regardless of size. Fluorescence microscopy shows all sizes of beads are concentrated in the siphons and are retained there for longer than one month postexposure. Combined atomic force microscopy- infrared spectroscopy and photothermal infrared spectroscopy are used to locate, image, and chemically identify the beads in the mussel siphons. In sum, these experiments demonstrate the potential for using mussels, specifically their siphons, to monitor environmental accumulation of aquatic nanoplastics.Can quagga mussels (Dreissena rostriformis bugensis), a widespread and invasive freshwater species that alters local ecosystems, act as a sentinel species for detecting nanoplastics? In the laboratory, mussels ingest and retain 200- 2000 nm fluorescent polystyrene beads, which are in the size range for the mussels’ preferred food and are trafficked like food in the ciliated grooves of the gills.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155884/1/gch2201800104-sup-0001-SuppMat.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155884/2/gch2201800104.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155884/3/gch2201800104_am.pd
Ga-68 DOTATATE Accumulation in Sarcoidosis
We aimed in this case series to show Ga-68 DOTATATE uptake in relation with disease activity in sarcoidosis cases. 8 patients with previous diagnosis of sarcoidosis were included to the study. Ga-68 DOTATATE PET/CT was performed to evaluate of disease activity. Disease activity was described clinically by chest disease specialist by evaluation of lung function tests, serum ACE measurements and thorax CT. Correlation between Ga-68 DOTATATE uptake and disease activity was analyzed. Ga-68 DOTATATE PET/CT as a combination of SSR scintigraphy and anatomical imaging might be beneficial in the evaluation of active sarcoidosis
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