456 research outputs found
Detection of Coronal Mass Ejections in V471 Tauri with the Hubble Space Telescope
V471 Tauri, an eclipsing system consisting of a hot DA white dwarf (WD) and a
dK2 companion in a 12.5-hour orbit, is the prototype of the pre-cataclysmic
binaries. The late-type component is magnetically active, due to its being
constrained to rotate synchronously with the short orbital period. During a
program of UV spectroscopy of V471 Tau, carried out with the Goddard High
Resolution Spectrograph (GHRS) onboard the Hubble Space Telescope, we
serendipitously detected two episodes in which transient absorptions in the Si
III 1206 A resonance line appeared suddenly, on a timescale of <2 min. The
observations were taken in a narrow spectral region around Ly-alpha, and were
all obtained near the two quadratures of the binary orbit, i.e., at maximum
projected separation (~3.3 Rsun) of the WD and K star.
We suggest that these transient features arise when coronal mass ejections
(CME's) from the K2 dwarf pass across the line of sight to the WD. Estimates of
the velocities, densities, and masses of the events in V471 Tau are generally
consistent with the properties of solar CME's. Given our detection of 2 events
during 6.8 hr of GHRS observing, along with a consideration of the restricted
range of latitudes and longitudes on the K star's surface that can give rise to
trajectories passing in front of the WD as seen from Earth, we estimate that
the active V471 Tau dK star emits some 100-500 CME's per day, as compared to
1-3 per day for the Sun. The K dwarf's mass-loss rate associated with CME's is
at least (5-25) x 10^{-14} Msun/yr, but it may well be orders of magnitude
higher if most of the silicon is in ionization states other than Si III.Comment: 24 pages AASTeX, 4 figures. Accepted by Astrophysical Journa
Assessment of Fishery Products Consumption Behavior: the Case of Turkey
From the early history of humanity until today, fish and other fishery products have always been involved in human diet. The intake of a sufficient number of proteins has been enabled through high-quality fish meat containing a significant quantity of essential amino acids as well as omega-3 fatty acids. According to the studies, 150 grams of fish, meets the needs of a 50-60% of daily protein intake for an adult. A large part of fishery production in Turkey (86%), is consumed fresh. Turkey, within the scope of Common Fisheries Policy is trying to harmonize fisheries with the EU. A failure to update the 1380 coded Fisheries Law and rapid issuing of EU compatible regulations, safe food for consumers, high quality products along the year for processing industry and marketers, as well as the inability to ensure sustainable price development for the producers, prevent the success of the sector. The aim of this study was to determine the consumption behavior when taking fishery products in terms of food safety, reliability, product quality as well as the level of income and education
Renal and suprarenal insufficiency secondary to familial Mediterranean fever associated with amyloidosis: a case report
<p>Abstract</p> <p>Introduction</p> <p>Familial Mediterranean fever is an autosomal recessive disease that predominantly affects people of the Mediterranean coast. One of the most frequent complications of the disease is amyloidosis. This clinical entity is known as secondary (also called AA) amyloidosis.</p> <p>Case presentation</p> <p>In this report, we describe the case of a 33-year-old Turkish man with familial Mediterranean fever and chronic renal insufficiency. He was admitted to our clinic with symptoms of suprarenal insufficiency. The patient died three months later as a result of cardiac arrest.</p> <p>Conclusion</p> <p>Our aim is to make a contribution to the literature by reporting a case of combined insufficiency due to the accumulation of renal and adrenal amyloid in a patient with familial Mediterranean fever, which has very rarely been described in the literature. We hope that adrenal insufficiency, which becomes fatal if not diagnosed and treated rapidly, will come to mind as easily as chronic renal failure in clinical practice.</p
Compatibility of MAX phase-based ceramics with oxygen-poor, static liquid lead-bismuth eutectic
This work investigates the compatibility of MAX phase-based
ceramics with liquid LBE, and proposes a mechanism to explain the observed
local /LBE interaction. The ceramics were exposed to oxygen-poor
( mass%), static liquid LBE at 500{\deg}C for 1000
h. A new MAX phase solid solution formed in-situ in the
LBE-affected grains. Out-of-plane ordering was favorable in the new
solid solution, whereby -layers with high and low-Bi/Pb contents
alternated in the crystal structure, in agreement with first-principles
calculations. Bulk was synthesized by reactive hot pressing
to study the crystal structure of the solid solution by neutron diffraction
Sourcing Flexibility, Spot Trading, and Procurement Contract Structure
We analyze the structure and pricing of option contracts for an industrial good in the presence of spot trading. We combine the analysis of spot trading and buyers' disparate private valuations for different suppliers' products, and we jointly endogenize the determination of three major dimensions in contract design: (i) sales contracts versus options contracts, (ii) flat-price versus volume-dependent contracts, and (iii) volume discounts versus volume premia. We build a model in which a supplier of an industrial good transacts with a manufacturer who uses the supplier's product to produce an end good with an uncertain demand. We show that, consistent with industry observations, volume-dependent optimal sales contracts always demonstrate volume discounts (i.e., involve concave pricing). However, options are more complex agreements, and optimal option contracts can involve both volume discounts and volume premia. Three major contract structures commonly emerge in optimality. First, if the seller has a high discount rate relative to the buyer and the seller's production costs or the production capacity is low, the optimal contracts tend to be flat-price sales contracts. Second, when the seller has a relatively high discount rate compared to the buyer but production costs or production capacity are high, the optimal contracts are sales contracts with volume discounts. Third, if the buyer's discount rate is high relative to the seller's, then the optimal contracts tend to be volume-dependent options contracts and can involve both volume discounts and volume premia. However, when the seller's production capacity is sufficiently low, it is possible to observe flat-price option contracts. Furthermore, we provide links between production and spot market characteristics, contract design, and efficiency.National Science Foundation (U.S.) (contract CMMI-0758069)National Science Foundation (U.S.) (contract DMI-0245352
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