110 research outputs found
Amplification by stochastic interference
A new method is introduced to obtain a strong signal by the interference of
weak signals in noisy channels. The method is based on the interference of 1/f
noise from parallel channels. One realization of stochastic interference is the
auditory nervous system. Stochastic interference may have broad potential
applications in the information transmission by parallel noisy channels
A genome-scale in vivo loss-of-function screen identifies Phf6 as a lineage-specific regulator of leukemia cell growth
We performed a genome-scale shRNA screen for modulators of B-cell leukemia progression in vivo. Results from this work revealed dramatic distinctions between the relative effects of shRNAs on the growth of tumor cells in culture versus in their native microenvironment. Specifically, we identified many “context-specific” regulators of leukemia development. These included the gene encoding the zinc finger protein Phf6. While inactivating mutations in PHF6 are commonly observed in human myeloid and T-cell malignancies, we found that Phf6 suppression in B-cell malignancies impairs tumor progression. Thus, Phf6 is a “lineage-specific” cancer gene that plays opposing roles in developmentally distinct hematopoietic malignancies.Massachusetts Institute of Technology. Department of Biology (Training Grant)National Cancer Institute (U.S.). Integrative Cancer Biology Program (U54-CA112967-06)National Institutes of Health (U.S.) (RO1-CA128803-05
Ephemeris Updates for Seven Selected HATNet Survey Transiting Exoplanets
We refined the ephemeris of seven transiting exoplanets HAT-P-6b, HAT-P-12b,
HAT-P-18b, HAT-P-22b, HAT-P-32b, HAT-P-33b, and HAT-P-52b. We observed 11
transits from eight observatories in different filters for HAT-P-6b and
HAT-P-32b. Also, the Exoplanet Transit Database (ETD) observations for each of
the seven exoplanets were analyzed, and the light curves of five systems were
studied using Transiting light Exoplanet Survey Satellite (TESS) data. We used
Exofast-v1 to simulate these ground- and space-based light curves and estimate
mid-transit times. We obtained a total of 11, 175 and 67 mid-transit times for
these seven exoplanets from our observations, ETD and TESS data, respectively,
along with 155 mid-transit times from the literature. Then, we generated
transit timing variation (TTV) diagrams for each using derived mid-transit
times as well as those found in the literature. The systems' linear ephemeris
was then refined and improved using the Markov Chain Monte Carlo (MCMC) method.
All of the studied exoplanets, with the exception of the HAT-P-12b system,
displayed an increasing trend in the orbital period in the TTV diagrams.Comment: 11 Pages, submitted to the Astrophysics journa
The known unknowns of hydraulic engineering
Hydraulic engineers and researchers deal with scientific challenges involving turbulent flow motion and its interactions with the surroundings. Turbulent flows are characterised by unpredictable behaviour, and little systematic research has yet been conducted in natural systems. This paper discusses the implications of recent developments in affordable instrumentation previously characterised by intrinsic weaknesses that adversely affect the quality of the signal outputs. A challenging application is the unsteady turbulence field in tidal bores. The interactions between open channel flows and movable boundaries and atmosphere illustrate another aspect of our limited knowledge. Rapid siltation of reservoirs and air entrainment in turbulent free-surface flows are discussed. In both applications, hydraulic engineers require some broad-based expertise. In turn the education of future hydraulic engineers is of vital importance
Assessment of Methods Used in 1D Models for Computing Bed-Load Transport in a Large River: The Danube River in Slovakia
Hydraulic engineering in the 21st century: Where to?
For centuries, hydraulic engineers were at the forefront of science. The last forty years marked a change of perception in our society with a focus on environmental sustainability and management, particularly in developed countries. Herein, the writer illustrates his strong belief that the future of hydraulic engineering lies upon a combination of innovative engineering, research excellence and higher education of quality. This drive continues a long tradition established by eminent scholars like Arthur Thomas IPPEN, John Fisher KENNEDY and Hunter ROUSE
Drag Reduction in Open Channel Flow by Aeration and Suspended Load
In supercritical open channel flows air is entrained at the free surface. Such air-water flows, called self-aerated flows, exhibit smaller friction losses than non-aerated flows. New data on drag reduction in self-aerated flows are presented. It is shown that the drag reduction process is linked with the presence of an air concentration boundary layer next to the channel bottom. An analogy with dilute polymer solutions and micro bubble modified boundary layers is developed and it is suggested that the presence of air next to the bottom increases the effective viscosity of the mixture and the sublayer thickness. A parallel with sediment laden flows is also developed. Although the distribution of suspended sediments differs from the distribution of air bubbles, it is suggested that the mechanisms of drag reduction observed in suspended sediment flows are similar to those in self-aerated flows
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