21,045 research outputs found
Far Infrared Slab Lensing and Subwavelength Imaging in Crystal Quartz
We examine the possibility of using negative refraction stemming from the
phonon response in an anisotropic crystal to create a simple slab lens with
plane parallel sides, and show that imaging from such a lens should be possible
at room temperature despite the effects of absorption that are inevitably
present due to phonon damping. In particular, we consider the case of crystal
quartz, a system for which experimental measurements consistent with all-angle
negative refraction have already been demonstrated. Furthermore, we investigate
the possibility of subwavelength imaging from such materials, and show that it
should be possible for certain configurations.Comment: 12 pages, 10 figure
Efficiency of low versus high airline pressure in stunning cattle with a pneumatically powered penetrating captive bolt gun
The efficiency of stunning cattle was assessed in 443 animals (304 pure Zebu and 139 crossbred cattle), being mainly mature bulls and cows. Cattle were stunned using a Jarvis pneumatically powered penetrating captive bolt gun operating with low (160–175 psi, N = 82) and high (190 psi, N = 363) airline pressure, which was within the manufactures specifications. Signs of brain function and the position of the shots on the heads were recorded after stunning. Velocity of the captive bolt and its physical parameters were calculated. Cattle shot with low pressures showed more rhythmic respiration (27 vs. 8%, P < 0.001), less tongue protrusion (4 vs. 12%, P = 0.03) and less masseter relaxation (22 vs. 48%, P < 0.001). There was an increased frequency of shots in the ideal position when cattle were shot with the low compared to high airline pressures (15.3 vs. 3.1%). Bolt velocity and its physical parameters were significantly (P < 0.01) higher when using high pressure. Airline pressures below 190 psi are inappropriate when shooting adult Zebu beef cattle with pneumatically powered penetrating captive bolt guns
Danos de gafanhotos (Orthoptera, Acrididae, Leptysminae) em reflorestamentos no Estado do Pará.
bitstream/item/27899/1/Com.Tec.206.pdfDisponível também on-line
Manejo do oídio da mangueira (Oidium mangiferae) na produção integrada de manga.
bitstream/CPATSA/33059/1/INT67.pd
Vitamina C em pimentas Capsicum annuum L. cv jalapeño produzidas em cultivo protegido ou em pleno sol e colhidas em diferentes pontos de maturação.
The First VLT FORS1 spectra of Lyman-break candidates in the HDF-S and AXAF Deep Field
We report on low-resolution multi-object spectroscopy of 30 faint targets (R
\~ 24-25) in the HDF-S and AXAF deep field obtained with the VLT Focal
Reducer/low dispersion Spectrograph (FORS1). Eight high-redshift galaxies with
2.75< z < 4 have been identified. The spectroscopic redshifts are in good
agreement with the photometric ones with a dispersion at z<2
and at z>2. The inferred star formation rates of the
individual objects are moderate, ranging from a few to a few tens solar masses
per year. Five out of the eight high-z objects do not show prominent emission
lines. One object has a spectrum typical of an AGN. In the AXAF field two
relatively close pairs of galaxies have been identified, with separations of
8.7 and 3.1 proper Mpc and mean redshifts of 3.11 and 3.93, respectively.Comment: 5 pages Latex, with 2 PostScript figures. Astronomy and Astrophysics,
in pres
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