31,572 research outputs found
Heat flow calorimeter
Heat flow calorimeter devices are used to measure heat liberated from or absorbed by an object. This device is capable of measuring the thermal output of sealed nickel-cadmium batteries or cells during charge-discharge cycles. An elongated metal heat conducting rod is coupled between the calorimeter vessel and a heat sink, thus providing the only heat exchange path from the calorimeter vessel itself
The effect of very low-calorie diets on renal and hepatic outcomes : a systematic review
Peer reviewedPublisher PD
Valuing Farmland Protection with Choice Experiments That Incorporate Preference Heterogeneity: Does Policy Guidance Depend On the Econometric Fine Print?
Although mixed logit models are common in stated preference applications, resulting welfare estimates can be sensitive to minor changes in specification. This can be of critical relevance for policy and welfare analysis, particularly if policymakers are unaware of practical implications. Drawing from an application to agricultural conservation in Georgia, this paper quantifies the sensitivity of welfare estimates to common variations in mixed logit specification and assesses practical implications for policy guidance. Results suggest that practitioners may wish to reevaluate modeling and reporting procedures to reflect the welfare and policy implications of common but often unnoticed variations in model specification.Willingness to Pay, Conservation Easement, PACE, Mixed Logit, Stated Preference, Environmental Economics and Policy, Land Economics/Use, Research Methods/ Statistical Methods, Q24, Q51,
Magnetic, Transport, and Thermal Properties of Single Crystals of the Layered Arsenide BaMn2As2
Growth of BaMn2As2 crystals using both MnAs and Sn fluxes is reported. Room
temperature crystallography, anisotropic isothermal magnetization M versus
field H and magnetic susceptibility chi versus temperature T, electrical
resistivity in the ab plane rho(T), and heat capacity C(T) measurements on the
crystals were carried out. The tetragonal ThCr2Si2-type structure of BaMn2As2
is confirmed. After correction for traces of ferromagnetic MnAs impurity phase
using M(H) isotherms, the inferred intrinsic chi(T) data of the crystals are
anisotropic with chi_{ab}/chi_{c} \approx 7.5 at T = 2 K. The temperature
dependences of the anisotropic chi data suggest that BaMn2As2 is a collinear
antiferromagnet at room temperature with the easy axis along the c axis, and
with an extrapolated Neel temperature T_N \sim 500 K. The rho(T) decreases with
decreasing T below 310 K but then increases below \sim 50 K, suggesting that
BaMn2As2 is a small band-gap semiconductor with an activation energy of order
0.03 eV. The C(T) data from 2 to 5 K are consistent with this insulating ground
state, exhibiting a low temperature Sommerfeld coefficient gamma = 0.0(4)
mJ/mol K^2. The Debye temperature is determined from these data to be theta_D =
246(4) K. BaMn2As2 is a potential parent compound for ThCr2Si2-type
superconductors.Comment: 7 pages, 6 figures; v2: typos corrected, additional data and
discussion, accepted for publication in Phys. Rev.
Preparation of monotectic alloys having a controlled microstructure by directional solidification under dopant-induced interface breakdown
Monotectic alloys having aligned spherical particles of rods of the minor component dispersed in a matrix of the major component are prepared by forming a melt containing predetermined amounts of the major and minor components of a chosen monotectic system, providing in the melt a dopant capable of breaking down the liquid solid interface for the chosen alloy, and directionally solidfying the melt at a selected temperature gradient and a selected rate of movement of the liquid-solid interface (growth rate). Shaping of the minor component into spheres or rods and the spacing between them are controlled by the amount of dopant and the temperature gradient and growth rate values. Specific alloy systems include Al Bi, Al Pb and Zn Bi, using a transition element such as iron
Performance of rocket nozzle materials with several solid propellants
Erosion resistance and thermal stress cracking tests of rocket nozzle materials with solid propellant
Wild record of an apple snail in the Waikato River, Hamilton, New Zealand and their incidence in freshwater aquaria
We report the discovery of a single specimen of a live apple snail Pomacea diffusa Blume 1957 (Ampullariidae: Prosobranchia), from the Waikato River, Hamilton city, central North Island, New Zealand. This species, along with the congeneric P. insularum, is imported for the aquarium trade, and its occurrence in the river likely stemmed from an aquarium release. A survey of 55 aquaria belonging to 43 hobbyists revealed 27 apple snails, with one owner having 22 snails. Assessment of environmental tolerances and impacts of P. diffusa, based largely on studies of the closely related and commonly confused congener P. bridgesii, suggests that direct habitat impacts by this species are likely to be minor. However, there could be indirect influences on native biodiversity through predation on eggs or competition for food supplies with other detritivorous species if densities were to become high. Water temperatures in the Waikato River below Hamilton (10-23˚C in 2009) may enable released individuals to persist for an extended period, and over summer may exceed the threshold required to enable breeding. However, population establishment would be most likely in locations where water is heated through geothermal influences or industrial cooling water discharges
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