1,793 research outputs found
From white elephant to Nobel Prize: Dennis Gabor’s wavefront reconstruction
Dennis Gabor devised a new concept for optical imaging in 1947 that went by a variety of names over the following decade: holoscopy, wavefront reconstruction, interference microscopy, diffraction microscopy and Gaboroscopy. A well-connected and creative research engineer, Gabor worked actively to publicize and exploit his concept, but the scheme failed to capture the interest of many researchers. Gabor’s theory was repeatedly deemed unintuitive and baffling; the technique was appraised by his contemporaries to be of dubious practicality and, at best, constrained to a narrow branch of science. By the late 1950s, Gabor’s subject had been assessed by its handful of practitioners to be a white elephant. Nevertheless, the concept was later rehabilitated by the research of Emmett Leith and Juris Upatnieks at the University of Michigan, and Yury Denisyuk at the Vavilov Institute in Leningrad. What had been judged a failure was recast as a success: evaluations of Gabor’s work were transformed during the 1960s, when it was represented as the foundation on which to construct the new and distinctly different subject of holography, a re-evaluation that gained the Nobel Prize for Physics for Gabor alone in 1971. This paper focuses on the difficulties experienced in constructing a meaningful subject, a practical application and a viable technical community from Gabor’s ideas during the decade 1947-1957
Quantum Criticality at the Origin of Life
Why life persists at the edge of chaos is a question at the very heart of
evolution. Here we show that molecules taking part in biochemical processes
from small molecules to proteins are critical quantum mechanically. Electronic
Hamiltonians of biomolecules are tuned exactly to the critical point of the
metal-insulator transition separating the Anderson localized insulator phase
from the conducting disordered metal phase. Using tools from Random Matrix
Theory we confirm that the energy level statistics of these biomolecules show
the universal transitional distribution of the metal-insulator critical point
and the wave functions are multifractals in accordance with the theory of
Anderson transitions. The findings point to the existence of a universal
mechanism of charge transport in living matter. The revealed bio-conductor
material is neither a metal nor an insulator but a new quantum critical
material which can exist only in highly evolved systems and has unique material
properties.Comment: 10 pages, 4 figure
I quanta acustici e la teoria dell’udito
Writing in 1946 and 1947, the author considers the possibility to describe acoustical phenomena with quantum methods, and emphasizes that such an approach on sound analysis connects very neatly with issues in the psychophysiology of hearing. Central to Gabor’s paper is a representation of sound signals including the explicit determination of both frequency and time variables (different from the classic Fourier analysis, where sound is analysed in terms of perfectly periodical oscillations, i.e. oscillations of indeterminate duration). The author illustrates an «information diagram» that splits the sound signal in «logons» or acoustical quanta, e.g. rectangular units of minimal time/frequency area. These latter are formally described as functions or «elementary signals» consisting of a real part (oscillation) and an imaginary part (a pseudo-Gaussian pulse). The author shows that the time/frequency unit area in the information diagram are subject to quantum uncertainty. And that the definition of such unit area of acoustical energy might definitely converge with a number of (then accepted) empirical measurements in the psychophysiology of hearing
Disruption Management in Passenger Railway Transportation
This paper deals with disruption management in passenger
railway transportation. In the disruption management process, many
actors belonging to different organizations play a role. In this paper
we therefore describe the process itself and the roles of the
different actors.
Furthermore, we discuss the three main subproblems in railway
disruption management: timetable adjustment, and rolling stock and
crew re-scheduling. Next to a general description of these problems,
we give an overview of the existing literature and we present some
details of the specific situations at DSB S-tog and NS. These are
the railway operators in the suburban area of Copenhagen, Denmark,
and on the main railway lines in the Netherlands, respectively.
Since not much research has been carried out yet on Operations
Research models for disruption management in the railway context,
models and techniques that have been developed for related problems
in the airline world are discussed as well.
Finally, we address the integration of the re-scheduling processes
of the timetable, and the resources rolling stock and crew
Pseudo-stokes vector from complex signal representation of a speckle pattern and its applications to micro-displacement measurement
Intrathecal trastuzumab: immunotherapy improves the prognosis of leptomeningeal metastases in HER-2+ breast cancer patient
Development of the Arizona Robotic Telescope Network
The Arizona Robotic Telescope Network (ARTN) project is a long term effort to
develop a system of telescopes to carry out a flexible program of PI observing,
survey projects, and time domain astrophysics including monitoring, rapid
response, and transient/target-of-opportunity followup. Steward Observatory
operates and shares in several 1-3m class telescopes with quality sites and
instrumentation, largely operated in classical modes. Science programs suited
to these telescopes are limited by scheduling flexibility and people-power of
available observers. Our goal is to adapt these facilities for multiple
co-existing queued programs, interrupt capability, remote/robotic operation,
and delivery of reduced data. In the long term, planning for the LSST era, we
envision an automated system coordinating across multiple telescopes and sites,
where alerts can trigger followup, classification, and triggering of further
observations if required, such as followup imaging that can trigger
spectroscopy. We are updating telescope control systems and software to
implement this system in stages, beginning with the Kuiper 61'' and Vatican
Observatory 1.8-m telescopes. The Kuiper 61'' and its Mont4K camera can now be
controlled and queue-scheduled by the RTS2 observatory control software, and
operated from a remote room at Steward. We discuss science and technical
requirements for ARTN, and some of the challenges in adapting heterogenous
legacy facilities, scheduling, data pipelines, and maintaining capabilities for
a diverse user base.Comment: Proceedings of SPIE Astronomical Telescopes & Instrumentation 2018,
Observatory Operations: Strategies, Processes, and Systems VI
AIM2 recognizes cytosolic dsDNA and forms a caspase-1-activating inflammasome with ASC
The innate immune system senses nucleic acids by germline-encoded pattern recognition receptors. RNA is sensed by Toll-like receptor members TLR3, TLR7 and TLR8, or by the RNA helicases RIG-I (also known as DDX58) and MDA-5 (IFIH1). Little is known about sensors for cytoplasmic DNA that trigger antiviral and/or inflammatory responses. The best characterized of these responses involves activation of the TANK-binding kinase (TBK1)-interferon regulatory factor 3 (IRF3) signalling axis to trigger transcriptional induction of type I interferon genes. A second, less well-defined pathway leads to the activation of an 'inflammasome' that, via caspase-1, controls the catalytic cleavage of the pro-forms of the cytokines IL1beta and IL18 (refs 6, 7). Using mouse and human cells, here we identify the PYHIN (pyrin and HIN domain-containing protein) family member absent in melanoma 2 (AIM2) as a receptor for cytosolic DNA, which regulates caspase-1. The HIN200 domain of AIM2 binds to DNA, whereas the pyrin domain (but not that of the other PYHIN family members) associates with the adaptor molecule ASC (apoptosis-associated speck-like protein containing a caspase activation and recruitment domain) to activate both NF-kappaB and caspase-1. Knockdown of Aim2 abrogates caspase-1 activation in response to cytoplasmic double-stranded DNA and the double-stranded DNA vaccinia virus. Collectively, these observations identify AIM2 as a new receptor for cytoplasmic DNA, which forms an inflammasome with the ligand and ASC to activate caspase-1
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