6,482 research outputs found
The phenazine pyocyanin is a terminal signalling factor in the quorum sensing network of Pseudomonas aeruginosa
Certain members of the fluorescent pseudomonads produce and secrete phenazines. These heterocyclic, redox-active compounds are toxic to competing organisms, and the cause of these antibiotic effects has been the focus of intense research efforts. It is largely unknown, however, how pseudomonads themselves respond to – and survive in the presence of – these compounds. Using Pseudomonas aeruginosa DNA microarrays and quantitative RT-PCR, we demonstrate that the phenazine pyocyanin elicits the upregulation of genes/operons that function in transport [such as the resistance-nodulation-cell division (RND) efflux pump MexGHI-OpmD] and possibly in redox control (such as PA2274, a putative flavin-dependant monooxygenase), and downregulates genes involved in ferric iron acquisition. Strikingly, mexGHI-opmD and PA2274 were previously shown to be regulated by the PA14 quorum sensing network that controls the production of virulence factors (including phenazines). Through mutational analysis, we show that pyocyanin is the physiological signal for the upregulation of these quorum sensing-controlled genes during stationary phase and that the response is mediated by the transcription factor SoxR. Our results implicate phenazines as signalling molecules in both P. aeruginosa PA14 and PAO1
0+ states and collective bands in 228Th studied by the (p,t) reaction
The excitation spectra in the deformed nucleus 228Th have been studied by
means of the (p,t)-reaction, using the Q3D spectrograph facility at the Munich
Tandem accelerator. The angular distributions of tritons were measured for
about 110 excitations seen in the triton spectra up to 2.5 MeV. Firm 0+
assignments are made for 17 excited states by comparison of experimental
angular distributions with the calculated ones using the CHUCK3 code.
Assignments up to spin 6+ are made for other states. Sequences of states are
selected which can be treated as rotational bands and as multiplets of
excitations. Moments of inertia have been derived from these sequences, whose
values may be considered as evidence of the two-phonon nature of most 0+
excitations. Experimental data are compared with interacting boson model and
quasiparticle-phonon model calculations and with experimental data for 229Pa.Comment: 21 pages, 14 figure
Elastic Form Factors of He up to Large
Elastic electron scattering off He and He has recently been studied
at forward and backward scattering angles in Hall A at JLab. The results will
provide accurate data on the elastic form factors, charge and magnetic for
He and charge only for He, up to squared momentum transfer -values
of 3.2 GeV.Comment: 3 pages, Proceedings of EFB2
11th–12th Grade: English Level 2, Learning Packet #1 • Theme: U. S. Bill of Rights
Day 1 • What is the Constitution?, Your rights in the United States, Science: water cycle
Day 2 • Your rights in the United States: journal, What is the Bill of Rights?, Bill of Rights chart, Condensation and precipitation
Day 3 • Your rights in the United States: protest, Using your vocabulary, Opinion writing, Clouds
Day 4 • Your rights in the United States: journal, Vocabulary review, States of water
Day 5 • Your rights in the United States: draw a picture, How does your picture show equality?, Solids, liquids, and gas examples
My Packet Journal
Reference Sheet
Answer Key
Enhanced heat capacity and a new temperature instability in superfluid He-4 in the presence of a constant heat flux near T-lambda
We present the first experimental evidence that the heat capacity of superfluid 4He, at temperatures very close to the lambda point Tλ, is enhanced by a constant heat flux Q. The heat capacity at constant Q, CQ, is predicted to diverge at a temperature Tc(Q)<Tλ at which superflow becomes unstable. In agreement with previous measurements, we find that dissipation enters our cell at a temperature, TDAS(Q), below the theoretical value, Tc(Q). We argue that TDAS(Q) can be accounted for by a temperature instability at the cell wall, and is therefore distinct from Tc(Q). The excess heat capacity we measure has the predicted scaling behavior as a function of T and Q, but it is much larger than predicted by current theory
11th–12th Grade: English Level 2, Learning Packet #3 • Theme: Susan B. Anthony
Day 1 • Journal: in your opinion, why is it important to vote?, Who was Susan B. Anthony?, Science: climate and biome where you\u27re from
Day 2 • Journal: what are some things you are good at?, Past and present tense, Past and present tense: play, Science: weather near the equator, Biomes
Day 3 • Journal: what was your favorite day of school?, Picture analysis, Science: climate far from the equator, Forests, Draw a picture
Day 4 • Journal: what is a time you convinced someone to do something?, The 19th Amendment, Science: clothes near the equator, Grasslands, Deserts
Day 5 • Journal: what are some things you want everyone to know about you?, Who should vote?, Do you think 16-year olds should vote?, Science: clothes far from the equator, Tundra
References
My Packet Journal
Reference Shee
Tracking Users across the Web via TLS Session Resumption
User tracking on the Internet can come in various forms, e.g., via cookies or
by fingerprinting web browsers. A technique that got less attention so far is
user tracking based on TLS and specifically based on the TLS session resumption
mechanism. To the best of our knowledge, we are the first that investigate the
applicability of TLS session resumption for user tracking. For that, we
evaluated the configuration of 48 popular browsers and one million of the most
popular websites. Moreover, we present a so-called prolongation attack, which
allows extending the tracking period beyond the lifetime of the session
resumption mechanism. To show that under the observed browser configurations
tracking via TLS session resumptions is feasible, we also looked into DNS data
to understand the longest consecutive tracking period for a user by a
particular website. Our results indicate that with the standard setting of the
session resumption lifetime in many current browsers, the average user can be
tracked for up to eight days. With a session resumption lifetime of seven days,
as recommended upper limit in the draft for TLS version 1.3, 65% of all users
in our dataset can be tracked permanently.Comment: 11 page
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