3,386 research outputs found
The Effects of CCA Preservative Treatment and Redrying on the Bending Properties of 2 X 6 Southern Pine Lumber
Southern pine dimension lumber (commercially graded No. 2 loblolly pine 2 x 6s) was treated with chromated copper arsenate (CCA) preservative (0.4 or 0.6 pcf) and then air-dried or kiln-dried (160, 190, or 240 F). CCA treatment significantly reduced average bending strength, but no discernible differences were found between controls and CCA-treated groups in the extreme lower portions (< 10th percentile) of the bending-strength distributions. When these same specimens were then considered solely on the basis of strength-reducing characteristics, there were obvious differences in how the CCA treatments and subsequent redrying affected these various strength-ratio grades of 2 x 6 lumber; higher grades appeared to be less affected than lower grades. Similar to the trend shown when commercially graded, the middle and upper portion of each strength-ratio grade bending-strength distribution than did drying at 240 F affected a broader range of the bending-srength distribution than did drying at 160 F. The broadened range of significant effects noted after high-temperature redrying indicates that posttreatment kiln-drying temperatures higher than 190 F should be avoided.The effects of CCA treatment and redrying were highly interactive with strength-ratio grade and the presence or absence of pith. CCA treatment reduced the strength of lumber containing pith and having a strength ratio of 0.65 and containing pith was not affected by CCA treatment. The magnitude of this pith-related interaction demands recognition
Graduate Education in Agricultural Communication: The Need and Role
Is there a meed for graduate studies in agricultural communication
EROs found behind lensing clusters: II.Empirical properties, classification, and SED modelling based on multi-wavelength observations
We study the properties and nature of extremely red galaxies (ERO, R-K>5.6)
found behind two lensing clusters and compare them with other known galaxy
populations. New HST/ACS observations, Spitzer IRAC and MIPS, and Chandra/ACIS
observations of the two lensing clusters Abell 1835 and AC114 contemplate our
earlier optical and near-IR observations and have been used to study extremely
red objects (EROs) in these deep fields. We have found 6 and 9 EROs in Abell
1835 and AC114. Several (7) of these objects are undetected up to the I and/or
z band, and are hence ``optical'' drop-out sources. The photometric redshifts
of most of our sources (80%) are z~0.7-1.5. According to simple colour-colour
diagrams the majority of our objects would be classified as hosting old stellar
populations. However, there are clear signs of dusty starbursts for several
among them. These objects correspond to the most extreme ones in R-K colour. We
estimate a surface density of (0.97+-0.31) arcmin-2 for EROs with (R-K>5.6) at
K<20.5. Among our 15 EROs 6 (40 %) also classify as distant red galaxies
(DRGs). 11 of 13 EROs with available IRAC photometry also fulfil the selection
criteria for IRAC selected EROs (IEROs) of Yan et al. (2004). SED modelling
shows that ~ 36 % of the IEROs in our sample are luminous or ultra-luminous
infrared galaxies ((U)LIRG). Some very red DRGs are found to be very dusty
starbursts, even (U)LIRGs, as also supported by their mid-IR photometry. No
indication for AGNs is found, although faint activity cannot be excluded for
all objects. From mid-IR and X-ray data 5 objects are clearly classified as
starbursts. The derived properties are quite similar to those of DRGs and
IEROs, except for 5 extreme objects in terms of colours, for which a very high
extinction (Av>3) is found.Comment: 20 pages, 10 figures, accepted for publication in A&
Molecular gas in NUclei of GAlaxies (NUGA) XV. Molecular gas kinematics in the inner 3kpc of NGC6951
Within the NUclei of GAlaxies project we have obtained IRAM PdBI and 30m
12CO(1-0) and 12CO(2-1) observations of the spiral galaxy NGC 6951. Previous
work shows that there is indirect evidence of gas inflow from 3 kpc down to
small radii: a large-scale stellar bar, a prominent starburst ring (r~580 pc)
and a LINER/Seyfert 2 nucleus. In this paper we study the gas kinematics as
traced by the CO line emission in detail. We quantify the influence of the
large-scale stellar bar by constructing an analytical model of the evolution of
gas particles in a barred potential. From this model gravitational torques and
mass accumulation rates are computed. We compare our model-based gravitational
torque results with previous observationally-based ones. The model also shows
that the large-scale stellar bar is indeed the dominant force for driving the
gas inward, to the starburst ring. Inside the ring itself a nuclear stellar
oval might play an important role. Detailed analysis of the CO gas kinematics
there shows that emission arises from two co-spatial, but kinematically
distinct components at several locations. The main emission component can
always be related to the overall bar-driven gas kinematics. The second
component exhibits velocities that are larger than expected for gas on stable
orbits, has a molecular gas mass of 1.8x10^6Msun, is very likely connected to
the nuclear stellar oval, and is consistent with inflowing motion towards the
very center. This may form the last link in the chain of gas inflow towards the
active galactic nucleus in NGC 6951.Comment: 17 pages, accepted by A&A (17 feb 2011
A Solar-Hydrogen Energy Conversion Scheme for Agricultural Use
A solar energy activated system is presented which can produce hydrogen and hydrogen-derived fuels (methanol) for use on farms. The device, named solar-kine , also can produce fertilizer (anhydrous ammonia) as a byproduct of the hydrogen. A cost analysis shows that solar-kine may be mass-producible and sold to farmers for between 14,700. This is equivalent to giving the fanner energy at a price of 3.66 per million BTU\u27s (in 1974 dollars). Presently (Spring, 1974) regular gasoline used in tractors at 43Âą per gallon, represents a cost to the farmer of $3.77 per million BTU\u27s. As oil-based fuels increase in price in the next few years, solar-kine may represent a reasonable alternative to keep food prices down.
The solar-kine system uses concentrated solar energy which can be converted into a high-density electric current by means of a thermionic heat engine. The rejected heat and electric current from the thermionic converter is supplied to an electrolysis cell which, in turn, produces hydrogen and oxygen gas. Chemical process equipment will use the hydrogen and oxygen to produce a methanol (CH3OH) fuel supply for internal combustion engines used on farm machines. The hydrogen can also be used to manufacture ammonia, ammonium nitrate (NH4NO3), and ammonium sulfate [(NH4)2SO4)] fertilizers. The following materials can be produced which are useful to the farmer: a) hydrogen gas, b) oxygen gas, c) liquid tractor fuel, d) fertilizer, e) ammonia, f) electricity, and e) heat energy
We feel that any unconventional energy system, such as solar-kine, must interface and serve the conventional use of fuel energy if it is to have lasting merits. This is why we feel that it is desirable to have the complete conversion of solar energy into a liquid fuel that is safe to handle and store, and which also can be used in any conventional fossil-fuel burning system with minimum modifications.
Solar energy is compatible with our environment; it is free, and its supply cannot be exhausted. It is also available at any geographic location without requiring transportation to the user\u27s site (See Fig. 2). Its major advantage over fossil fuel comes from the fact that it does not add any net heat content to the earth [5,6].
A small on-site energy system is best for the farmer because,
a) It can be mass produced at 106 or more, units per year,b) Power levels needed by farms are low, 100-500 KW, c)Farm energy is used over a large geographical area, d)The main source of energy (the sun) is everywhere available,e) Heat rejected from the heat engine (thermionic) is used in other portions of the system to increase overall efficiency, and may be used in part to heat buildings,f) The farmer would be energy-independent from the price and supply undulations of the industrial complex,g) Legal considerations which regulate the large energy distribution systems would not apply, or affect, the proposed system as used by the farmer,h) Last, and possibly most important, the farmer would have a dependable fuel supply at the lowest possible cost. In the future, the proposed system will supply energy at a cost much lower than petroleum-derived energy
The first Frontier Fields cluster: 4.5{\mu}m excess in a z~8 galaxy candidate in Abell 2744
We present in this letter the first analysis of a z~8 galaxy candidate found
in the Hubble and Spitzer imaging data of Abell 2744, as part of the Hubble
Frontier Fields legacy program. We applied the most commonly-used methods to
select exceptionally high-z galaxies by combining non-detection and
color-criteria using seven HST bands. We used GALFIT on IRAC images for fitting
and subtracting contamination of bright nearby sources. The physical properties
have been inferred from SED-fitting using templates with and without nebular
emission. This letter is focussed on the brightest candidate we found
(m=26.2) over the 4.9 arcmin field of view covered by the WFC3.
It shows a non-detection in the ACS bands and at 3.6{\mu}m whereas it is
clearly detected at 4.5{\mu}m with rather similar depths. This break in the
IRAC data could be explained by strong [OIII]+H{\beta} lines at z~8 which
contribute to the 4.5{\mu}m photometry. The best photo-z is found at
z~8.0, although solutions at low-redshift (z~1.9) cannot be
completely excluded, but they are strongly disfavoured by the SED-fitting work.
The amplification factor is relatively small at {\mu}=1.490.02. The Star
Formation Rate in this object is ranging from 8 to 60 Mo/yr, the stellar mass
is in the order of M=(2.5-10) x 10Mo and the size is
r~0.350.15 kpc. This object is one of the first z~8 LBG candidates showing
a clear break between 3.6{\mu}m and 4.5{\mu}m which is consistent with the IRAC
properties of the first spectroscopically confirmed galaxy at a similar
redshift. Due to its brightness, the redshift of this object could potentially
be confirmed by near infrared spectroscopy with current 8-10m telescopes. The
nature of this candidate will be revealed in the coming months with the arrival
of new ACS and Spitzer data, increasing the depth at optical and near-IR
wavelengths.Comment: 4 pages, 2 figures, Accepted for publication in Astronomy and
Astrophysics Letter
ALMA detection of [CII] 158 micron emission from a strongly lensed z=2 star-forming galaxy
Our objectives are to determine the properties of the interstellar medium
(ISM) and of star-formation in typical star-forming galaxies at high redshift.
Following up on our previous multi-wavelength observations with HST, Spitzer,
Herschel, and the Plateau de Bure Interferometer (PdBI), we have studied a
strongly lensed z=2.013 galaxy, the arc behind the galaxy cluster MACS
J0451+0006, with ALMA to measure the [CII] 158 micron emission line, one of the
main coolants of the ISM. [CII] emission from the southern part of this galaxy
is detected at 10 . Taking into account strong gravitational lensing,
which provides a magnification of , the intrinsic lensing-corrected
[CII]158 micron luminosity is . The observed
ratio of [CII]-to-IR emission, , is found to be similar to that in nearby galaxies. The same also
holds for the observed ratio , which is
comparable to that of star-forming galaxies and active galaxy nuclei (AGN) at
low redshift. We utilize strong gravitational lensing to extend diagnostic
studies of the cold ISM to an order of magnitude lower luminosity () and SFR than previous work at high redshift.
While larger samples are needed, our results provide evidence that the cold ISM
of typical high redshift galaxies has physical characteristics similar to
normal star forming galaxies in the local Universe.Comment: 5 pages, 4 figures. Accepted for publication in Astronomy &
Astrophysics, Letter
Feeding AGN: new results from the NUGA survey
The NUGA project is a high-resolution (0.5''-1'') CO survey of low luminosity
AGN including the full sequence of activity types (Seyferts, LINERs and
transition objects). NUGA aims to systematically study the different mechanisms
for gas fueling of AGNs in the Local Universe. In this paper we discuss the
latest results of this recently completed survey, which now includes newly
acquired subarcsec resolution observations for all targets of the sample. The
large variety of circumnuclear disk morphologies found in NUGA galaxies (m=1,
m=2 and stochastic instabilities) is a challenging result that urges the
refinement of current dynamical models. In this paper we report on new results
obtained in 4 study cases for NUGA: NGC4826, NGC7217, NGC4579 and NGC6951Comment: 4 pages, 2 figures. Contributed talk to appear in "The Interplay
among Black Holes, Stars and ISM in Galactic Nuclei," Proc. IAU 222 (Gramado,
Brazil), eds. Th. Storchi Bergmann, L.C. Ho, H.R. Schmit
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