1,003 research outputs found
Apparatus for making curved reflectors Patent
Forming mold for polishing and machining curved solar magnesium reflector with reinforcing rib
Process sequence produces strong, lightweight reflectors of excellent quality
Large compound curved surfaces for collecting and concentrating radiation are fabricated by the use of several common machining and forming processes. Lightweight sectors are assembled into large reflectors. With this concept of fabrication, integrally stiffened reflective sectors up to 25 square feet in area have been produced
Method and apparatus for making curved reflectors Patent
Fabrication of curved reflector segments for solar mirro
Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments
To examine the potential influence of terrestrially derived DOM on the Baltic
Sea, a year-long study of dissolved organic matter (DOM) was performed in
three river catchments in Sweden. One catchment drains into the Bothnian Sea,
while two southern catchments drain into the Baltic proper. Dissolved organic
carbon (DOC) concentrations were positively correlated with discharge from
forested catchments over the year. While the overall concentrations of DOC
were several times higher in the southern two catchments, higher discharge in
the northern catchment resulted in the annual loadings of DOC being on the
same order of magnitude for all three catchments. Biological oxygen demand
(BOD) was used as a proxy for the lability of carbon in the system. The range
of BOD values was similar for all three catchments, however, the ratio of BOD
to DOC (an indication of the labile fraction) in Ume river was four times
higher than in the southern two catchments. Total annual BOD loading to the
Baltic Sea was twice as high in the northern catchment than in the two
southern catchments. Lower winter temperatures and preservation of organic
matter in the northern catchment combined with an intense spring flood help
to explain the higher concentrations of labile carbon in the northern
catchment. Lower lability of DOM as well as higher colour in the southern
catchments suggest that wetlands (i.e. peat bogs) may be the dominant source
of DOM in these catchments, particularly in periods of low flow. With climate
change expected to increase precipitation events and temperatures across the
region, the supply and quality of DOM delivered to the Baltic Sea can also be
expected to change. Our results indicate that DOM supply to the Baltic Sea
from boreal rivers will be more stable throughout the year, and potentially
have a lower bioavailability
Atomic Spectroscopic Databases at NIST
We describe recent work at NIST to develop and maintain databases for spectra, transition probabilities, and energy levels of atoms that are astrophysically important. Our programs to critically compile these data as well as to develop a new database to compare plasma calculations for atoms that are not in local thermodynamic equilibrium are also summarized
EUV spectra of highly-charged ions W-W relevant to ITER diagnostics
We report the first measurements and detailed analysis of extreme ultraviolet
(EUV) spectra (4 nm to 20 nm) of highly-charged tungsten ions W to
W obtained with an electron beam ion trap (EBIT). Collisional-radiative
modelling is used to identify strong electric-dipole and magnetic-dipole
transitions in all ionization stages. These lines can be used for impurity
transport studies and temperature diagnostics in fusion reactors, such as ITER.
Identifications of prominent lines from several W ions were confirmed by
measurement of isoelectronic EUV spectra of Hf, Ta, and Au. We also discuss the
importance of charge exchange recombination for correct description of
ionization balance in the EBIT plasma.Comment: 11 pages, 4 figure
Production of Sodium Bose--Einstein condensates in an optical dimple trap
We report on the realization of a sodium Bose--Einstein condensate (BEC) in a
combined red-detuned optical dipole trap, formed by two beams crossing in a
horizontal plane and a third, tightly focused dimple trap propagating
vertically. We produce a BEC in three main steps: loading of the crossed dipole
trap from laser-cooled atoms, an intermediate evaporative cooling stage which
results in efficient loading of the auxiliary dimple trap, and a final
evaporative cooling stage in the dimple trap. Our protocol is implemented in a
compact setup and allows us to reach quantum degeneracy even with relatively
modest initial atom numbers and available laser power
Motion-corrected reconstruction of parametric images from dynamic PET data with the Synergistic Image Reconstruction Framework (SIRF)
Motion correction has been added to a PET-MR reconstruction tool, SIRF, by incorporating a registration package, NiftyReg. New functionality has been demonstrated in the context of estimating kinetic parameters in the left temporal lobe, comparing direct and indirect reconstructions and evaluating the impact of using motion correction.Principal component analysis was used to detect motion and to determine time frames, while STIR's parametric-OSEM was used to perform the motion-corrected direct parametric reconstruction.It was found that the variance in the left temporal lobe decreased when motion correction was performed, and the same was true of direct reconstructions compared to indirect.With SIRF, the entirety of the demonstrated functionality can be performed from a single Matlab or Python script
Eukaryotic initiation factor 6 regulates mechanical responses in endothelial cells
The repertoire of extratranslational functions of components of the protein synthesis apparatus is expanding to include control of key cell signaling networks. However, very little is known about noncanonical functions of members of the protein synthesis machinery in regulating cellular mechanics. We demonstrate that the eukaryotic initiation factor 6 (eIF6) modulates cellular mechanobiology. eIF6-depleted endothelial cells, under basal conditions, exhibit unchanged nascent protein synthesis, polysome profiles, and cytoskeleton protein expression, with minimal effects on ribosomal biogenesis. In contrast, using traction force and atomic force microscopy, we show that loss of eIF6 leads to reduced stiffness and force generation accompanied by cytoskeletal and focal adhesion defects. Mechanistically, we show that eIF6 is required for the correct spatial mechanoactivation of ERK1/2 via stabilization of an eIF6-RACK1-ERK1/2-FAK mechanocomplex, which is necessary for force-induced remodeling. These results reveal an extratranslational function for eIF6 and a novel paradigm for how mechanotransduction, the cellular cytoskeleton, and protein translation constituents are linked
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