2,320 research outputs found
Mechanical device accurately measures rf phase differences in vhf or uhf ranges
Dual range linear measurement device accurately measures RF phase differences in either VHF or UHF ranges. The device has a capability consisting of a course range extending to 30 cm readable to 1 mm and any fine range portion of 2.5 cm readable to .01 mm
Reinforcing attitudes in a gatewatching news era: individual-level antecedents to sharing fact-checks on social media
Despite the prevalence of fact-checking, little is known about who posts fact-checks online. Based upon a content analysis of Facebook and Twitter digital trace data and a linked online survey (N = 783), this study reveals that sharing fact-checks in political conversations on social media is linked to age, ideology, and political behaviors. Moreover, an individual’s need for orientation (NFO) is an even stronger predictor of sharing a fact-check than ideological intensity or relevance, alone, and also influences the type of fact-check format (with or without a rating scale) that is shared. Finally, participants generally shared fact-checks to reinforce their existing attitudes. Consequently, concerns over the effects of fact-checking should move beyond a limited-effects approach (e.g., changing attitudes) to also include reinforcing accurate beliefs.Accepted manuscrip
A deep i-selected multi-waveband galaxy catalogue in the COSMOS field
In this paper we present a deep and homogeneous i-band selected
multi-waveband catalogue in the COSMOS field covering an area of about 0.7
square-degree. Our catalogue with a formal 50 percent completeness limit for
point sources of i~26.7 comprises about 290.000 galaxies with information in 8
passbands. We combine publicly available u, B, V, r, i, z, and K data with
proprietary imaging in H band. We discuss in detail the observations, the data
reduction, and the photometric properties of the H-band data. We estimate
photometric redshifts for all the galaxies in the catalogue. A comparison with
162 spectroscopic redshifts in the redshift range 0 < z < 3 shows that the
achieved accuracy of the photometric redshifts is (Delta_z / (z_spec+1)) ~0.035
with only ~2 percent outliers. We derive absolute UV magnitudes and investigate
the evolution of the luminosity function evaluated in the rest-frame UV at 1500
Angstrom. There is a good agreement between the LFs derived here and the LFs
derived in the FORS Deep Field. We see a similar brightening of M_star and a
decrease of phi_star with redshift. The catalogue including the photometric
redshift information is made publicly available.Comment: 20 pages, 17 figures, accepted for publication in MNRAS; high
resulution paper: http://www.mpe.mpg.de/~gabasch/COSMOS/cosmos.pd
Water and Watercourses—Federal Jurisdiction—Federal Common Law Determines Ownership of Re-Exposed Navigable River Beds—Bonelli Cattle Co. v. Arizona, 414 U.S. 313 (1973)
Plaintiff Bonelli Cattle Company (Bonelli) brought a quiet title action against the State of Arizona to determine ownership of newly reemerged land purchased by Bonelli in 1955 from a federal grantee, the Santa Fe Railroad. When the Santa Fe obtained the parcel in 1910, it comprised 280 acres of dry land. In that year the Colorado River, a navigable stream, formed the boundary between Arizona and Nevada and flowed more than one-quarter mile to the west. However, the Colorado moved slowly eastward so that in 1955 it covered all but 60 acres of the parcel. The submerged portion was re-exposed as a result of dredging and rechannelization of the river in 1959 and 1960 by the United States Bureau of Reclamation. The trial court and the intermediate appellate court upheld Bonelli\u27s claim to the re-exposed portion of the parcel. The Arizona Supreme Court reversed, holding that the re-emergence was caused by artificial, avulsive forces, and hence under state law the re-exposed land belonged to the state (whose title to the river bed had moved with the river). On certiorari the United States Supreme Court reversed. Held: Under the federal common law of accretion, a state\u27s ownership of the newly exposed bed of an inland navigable waterway is defeasible in favor of the riparian federal grantee, absent the state\u27s showing of any need to protect a public benefit or purpose. Bonelli Cattle Co. v. Arizona, 414 U.S. 313 (1973)
Baade's red sheet resolved into stars with HST in the Blue Compact Dwarf Galaxy VII Zw 403
HST WFPC2 observations of the nearby Blue Compact Dwarf Galaxy VII~Zw~403 (=
UGC 6456) resolve single stars down to M-2.5, deep enough to
identify red giants. This population has a more uniform spatial distribution
than the young main-sequence stars and supergiants, forming the structure known
as "Baade's red sheet". We conclude that VII~Zw~403 is not a primeval galaxy.Comment: submitted to: ApJ Letter
The stellar mass function of galaxies to z ~ 5 in the Fors Deep and GOODS-S fields
We present a measurement of the evolution of the stellar mass function (MF)
of galaxies and the evolution of the total stellar mass density at 0<z<5. We
use deep multicolor data in the Fors Deep Field (FDF; I-selected reaching
I_AB=26.8) and the GOODS-S/CDFS region (K-selected reaching K_AB=25.4) to
estimate stellar masses based on fits to composite stellar population models
for 5557 and 3367 sources, respectively. The MF of objects from the GOODS-S
sample is very similar to that of the FDF. Near-IR selected surveys hence
detect the more massive objects of the same principal population as do
I-selected surveys. We find that the most massive galaxies harbor the oldest
stellar populations at all redshifts. At low z, our MF follows the local MF
very well, extending the local MF down to 10^8 Msun. The faint end slope is
consistent with the local value of alpha~1.1 at least up to z~1.5. Our MF also
agrees very well with the MUNICS and K20 results at z<2. The MF seems to evolve
in a regular way at least up to z~2 with the normalization decreasing by 50% to
z=1 and by 70% to z=2. Objects having M>10^10 Msun which are the likely
progenitors of todays L* galaxies are found in much smaller numbers above z=2.
However, we note that massive galaxies with M>10^11 Msun are present even to
the largest redshift we probe. Beyond z=2 the evolution of the mass function
becomes more rapid. We find that the total stellar mass density at z=1 is 50%
of the local value. At z=2, 25% of the local mass density is assembled, and at
z=3 and z=5 we find that at least 15% and 5% of the mass in stars is in place,
respectively. The number density of galaxies with M>10^11 Msun evolves very
similarly to the evolution at lower masses. It decreases by 0.4 dex to z=1, by
0.6 dex to z=2, and by 1 dex to z=4.Comment: Accepted for publication in ApJ
The malaria parasite cyclic GMP-dependent protein kinase plays a central role in blood-stage schizogony
A role for the Plasmodium falciparum cyclic GMP (cGMP)-dependent protein kinase (PfPKG) in gametogenesis in the malaria parasite was elucidated previously. In the present study we examined the role of PfPKG in the asexual blood-stage of the parasite life cycle, the stage that causes malaria pathology. A specific PKG inhibitor (compound 1, a trisubstituted pyrrole) prevented the progression of P. falciparum schizonts through to ring stages in erythrocyte invasion assays. Addition of compound 1 to ring-stage parasites allowed normal development up to 30 h postinvasion, and segmented schizonts were able to form. However, synchronized schizonts treated with compound 1 for ≥6 h became large and dysmorphic and were unable to rupture or liberate merozoites. To conclusively demonstrate that the effect of compound 1 on schizogony was due to its selective action on PfPKG, we utilized genetically manipulated P. falciparum parasites expressing a compound 1-insensitive PfPKG. The mutant parasites were able to complete schizogony in the presence of compound 1 but not in the presence of the broad-spectrum protein kinase inhibitor staurosporine. This shows that PfPKG is the primary target of compound 1 during schizogony and provides direct evidence of a role for PfPKG in this process. Discovery of essential roles for the P. falciparum PKG in both asexual and sexual development demonstrates that cGMP signaling is a key regulator of both of these crucial life cycle phases and defines this molecule as an exciting potential drug target for both therapeutic and transmission blocking action against malaria
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