7,285 research outputs found
Proteomic Analysis of a Noninvasive Human Model of Acute Inflammation and Its Resolution: The Twenty-one Day Gingivitis Model
The 21-day experimental gingivitis model, an established noninvasive model of inflammation in response to increasing bacterial accumulation in humans, is designed to enable the study of both the induction and resolution of inflammation. Here, we have analyzed gingival crevicular fluid, an oral fluid comprising a serum transudate and tissue exudates, by LC−MS/MS using Fourier transform ion cyclotron resonance mass spectrometry and iTRAQ isobaric mass tags, to establish meta-proteomic profiles of inflammation-induced changes in proteins in healthy young volunteers. Across the course of experimentally induced gingivitis, we identified 16 bacterial and 186 human proteins. Although abundances of the bacterial proteins identified did not vary temporally, Fusobacterium outer membrane proteins were detected. Fusobacterium species have previously been associated with periodontal health or disease. The human proteins identified spanned a wide range of compartments (both extracellular and intracellular) and functions, including serum proteins, proteins displaying antibacterial properties, and proteins with functions associated with cellular transcription, DNA binding, the cytoskeleton, cell adhesion, and cilia. PolySNAP3 clustering software was used in a multilayered analytical approach. Clusters of proteins that associated with changes to the clinical parameters included neuronal and synapse associated proteins
Carrier mode selective working point and side band imbalance in LIGO I
In gravitational wave interferometers, the input laser beam is phase modulated to generate radio-frequency side bands that are used to lock the cavities. The mechanism is the following: the frequency of the side bands and the carrier is chosen in such a way that their response to small changes of the longitudinal degrees of freedom is different. This difference is therefore monitored and it serves as an error signal for controlling the optical cavity lengths, as they are linearly related to the set of observed phases between carrier and side bands. Among the others, one longitudinal degree of freedom is optimally sensitive to the space-time distortions propagating through the cosmos, as predicted by the general theory of relativity. The observation of the astrophysical signal relies on the measurement of that specific degree of freedom. The entire problem is more complex when the transverse degrees of freedom are taken into account, because the relative phase between the fields also depends on their overlap. In order to establish an unambiguous relation between length changes and phase measurements, there must be one circulating optical mode and the only difference between carrier and side bands must be their amplitude. We will show that the variability of the transverse degrees of freedom and their different actions on carrier and side band fields puts a severe limit on this assumption. Unless the system is made of perfect and perfectly matched optical cavities, it is never governed by one unique coherent state and any adjustment of the optical lengths results from a compromise between the lengths that are optimal for the carrier field and the side band ones. Such a compromise alters the correspondence between error signals and cavity lengths, calculated in the one-dimensional treatment. We assess the strength of this effect and relate it to the sensitivity of the instrument (which relies on the reconstruction of that correspondence) in realistic circumstances
OAM multiple transmission using uniform circular arrays: numerical modeling and experimental verification with two digital television signals
In this work we present the outcomes of a radio-frequency OAM transmission
between two antenna arrays performed in a real-world context. The analysis is
supplemented by deep simulative investigations able to provide both a
preliminary overview of the experimental scenario and a posteriori validation
of the achieved results. As a first step, the far-field OAM communication link
is tested at various frequencies and the corresponding link budget is studied
by means of an angular scan generated by the rotation of the receiving system.
Then, on the same site, two digital television signals encoded as OAM modes
(=1 and =-1) are simultaneously transmitted at a common frequency
of 198.5 MHz with good mode insulation.Comment: 16 pages, 14 figure
Probing Ultrafast Dynamics with Time-resolved Multi-dimensional Coincidence Imaging: Butadiene
Time-resolved coincidence imaging of photoelectrons and photoions represents
the most complete experimental measurement of ultrafast excited state dynamics,
a multi-dimensional measurement for a multi-dimensional problem. Here we
present the experimental data from recent coincidence imaging experiments,
undertaken with the aim of gaining insight into the complex ultrafast
excited-state dynamics of 1,3-butadiene initiated by absorption of 200 nm
light. We discuss photoion and photoelectron mappings of increasing
dimensionality, and focus particularly on the time-resolved photoelectron
angular distributions (TRPADs), expected to be a sensitive probe of the
electronic evolution of the excited state and to provide significant
information beyond the time-resolved photoelectron spectrum (TRPES). Complex
temporal behaviour is observed in the TRPADs, revealing their sensitivity to
the dynamics while also emphasising the difficulty of interpretation of these
complex observables. From the experimental data some details of the wavepacket
dynamics are discerned relatively directly, and we make some tentative
comparisons with existing ab initio calculations in order to gain deeper
insight into the experimental measurements; finally, we sketch out some
considerations for taking this comparison further in order to bridge the gap
between experiment and theory.Comment: 18 pages, 10 figures. Pre-print of JMO submissio
Detection of Sparse Anomalies in High-Dimensional Network Telescope Signals
Network operators and system administrators are increasingly overwhelmed with
incessant cyber-security threats ranging from malicious network reconnaissance
to attacks such as distributed denial of service and data breaches. A large
number of these attacks could be prevented if the network operators were better
equipped with threat intelligence information that would allow them to block or
throttle nefarious scanning activities. Network telescopes or "darknets" offer
a unique window into observing Internet-wide scanners and other malicious
entities, and they could offer early warning signals to operators that would be
critical for infrastructure protection and/or attack mitigation. A network
telescope consists of unused or "dark" IP spaces that serve no users, and
solely passively observes any Internet traffic destined to the "telescope
sensor" in an attempt to record ubiquitous network scanners, malware that
forage for vulnerable devices, and other dubious activities. Hence, monitoring
network telescopes for timely detection of coordinated and heavy scanning
activities is an important, albeit challenging, task. The challenges mainly
arise due to the non-stationarity and the dynamic nature of Internet traffic
and, more importantly, the fact that one needs to monitor high-dimensional
signals (e.g., all TCP/UDP ports) to search for "sparse" anomalies. We propose
statistical methods to address both challenges in an efficient and "online"
manner; our work is validated both with synthetic data as well as real-world
data from a large network telescope
Nanomechanical single-photon routing
The merger between integrated photonics and quantum optics promises new
opportunities within photonic quantum technology with the very significant
progress on excellent photon-emitter interfaces and advanced optical circuits.
A key missing functionality is rapid circuitry reconfigurability that
ultimately does not introduce loss or emitter decoherence, and operating at a
speed matching the photon generation and quantum memory storage time of the
on-chip quantum emitter. This ambitious goal requires entirely new active
quantum-photonic devices by extending the traditional approaches to
reconfigurability. Here, by merging nano-optomechanics and deterministic
photon-emitter interfaces we demonstrate on-chip single-photon routing with low
loss, small device footprint, and an intrinsic time response approaching the
spin coherence time of solid-state quantum emitters. The device is an essential
building block for constructing advanced quantum photonic architectures
on-chip, towards, e.g., coherent multi-photon sources, deterministic
photon-photon quantum gates, quantum repeater nodes, or scalable quantum
networks.Comment: 7 pages, 3 figures, supplementary informatio
A time-dependent Schr\"odinger equation for molecular core-hole dynamics
X-ray spectroscopy is an important tool for the investigation of matter. X
rays primarily interact with inner-shell electrons creating core (inner-shell)
holes that will decay on the time scale of attoseconds to few femtoseconds
through electron relaxations involving the emission of a photon or an electron.
The advent of femtosecond x-ray pulses expands x-ray spectroscopy to the time
domain and will eventually allow the control of core-hole population on
timescales comparable to core-vacancy lifetimes. For both cases, a theoretical
approach that accounts for the x-ray interaction while the electron relaxations
occur is required. Here we describe a time-dependent framework, based on
solving the time-dependent Schr\"odinger equation, that is suitable for
describing the induced electron and nuclear dynamics
Predicting the statistics of wave transport through chaotic cavities by the Random Coupling Model: a review and recent progress
In this review, a model (the Random Coupling Model) that gives a statistical
description of the coupling of radiation into and out of large enclosures
through localized and/or distributed channels is presented. The Random Coupling
Model combines both deterministic and statistical phenomena. The model makes
use of wave chaos theory to extend the classical modal description of the
cavity fields in the presence of boundaries that lead to chaotic ray
trajectories. The model is based on a clear separation between the universal
statistical behavior of the isolated chaotic system, and the deterministic
coupling channel characteristics. Moreover, the ability of the random coupling
model to describe interconnected cavities, aperture coupling, and the effects
of short ray trajectories is discussed. A relation between the random coupling
model and other formulations adopted in acoustics, optics, and statistical
electromagnetics, is examined. In particular, a rigorous analogy of the random
coupling model with the Statistical Energy Analysis used in acoustics is
presented.Comment: 32 pages, 9 figures, submitted to 'Wave Motion', special issue
'Innovations in Wave Model
- …