178 research outputs found
Searching for gravitational wave burst in PTA data with piecewise linear functions
Transient gravitational waves (aka gravitational wave bursts) within the
nanohertz frequency band could be generated by a variety of astrophysical
phenomena such as the encounter of supermassive black holes, the kinks or cusps
in cosmic strings, or other as-yet-unknown physical processes. Radio-pulses
emitted from millisecond pulsars could be perturbed by passing gravitational
waves, hence the correlation of the perturbations in a pulsar timing array can
be used to detect and characterize burst signals with a duration of
years. We propose a fully Bayesian framework for the
analysis of the pulsar timing array data, where the burst waveform is
generically modeled by piecewise straight lines, and the waveform parameters in
the likelihood can be integrated out analytically. As a result, with merely
three parameters (in addition to those describing the pulsars' intrinsic and
background noise), one is able to efficiently search for the existence and the
sky location of {a burst signal}. If a signal is present, the posterior of the
waveform can be found without further Bayesian inference. We demonstrate this
model by analyzing simulated data sets containing a stochastic gravitational
wave background {and a burst signal generated by the parabolic encounter of two
supermassive black holes.Comment: 13 pages, 10 figure
Cold-Season Surface Energy Balance on East Rongbuk Glacier, Northern Slope of Mt. Qomolangma (Everest)
As the highest peak on the earth, Mt. Qomolangma provides an unparalleled platform to study glacier-atmosphere interaction. Although glacier surface energy balance (SEB) on Mt. Qomolangma was examined during warm season, relevant knowledge during cold season is still unknown, which prevents a complete understanding of all-season glacier SEB on it. Based on an in-situ observation from October 2007 to January 2008, this study presents a cold-season glacier SEB result at 6,523 m above sea level on Mt. Qomolangma and identifies its atmospheric control. Our results show that the observational period experienced strong winds and deficient clouds. Near-surface wind speeds usually exceeded 10 m sâ1, resulting in a substantial sensible heat transport toward glacier and thus enhancing outgoing longwave radiation, which, under the combined effect of deficient clouds, eventually caused an increase in longwave radiative loss. The large solar zenith angle and relatively high albedo of the glacier surface led to a small absorption of solar irradiance, which, in combination with the strong longwave radiation loss, resulted in a semi-permanent surface radiative loss. Uncommon over the highly reflective glacier surface, clouds decreased the incident solar radiation more than increased the longwave radiation, demonstrating that the clouds' shading effect surpassed its greenhouse effect. As a vital heat sink, the turbulent latent heat induced an average sublimation rate of 0.8 mm water equivalent per day. This study provides valuable insights into the atmospheric control on the cold-season glacier-atmosphere interaction at high altitudes on Mt. Qomolangma when meteorological variables are subject to the westerlies
Histological study of the effect of some irrigating solutions on bacterial endotoxin in dogs
Residual antibacterial activity of chlorhexidine digluconate and camphorated p-monochlorophenol in calcium hydroxide-based root canal dressings
Recommended from our members
Three-dimensional, multifunctional neural interfaces for cortical spheroids and engineered assembloids.
Three-dimensional (3D), submillimeter-scale constructs of neural cells, known as cortical spheroids, are of rapidly growing importance in biological research because these systems reproduce complex features of the brain in vitro. Despite their great potential for studies of neurodevelopment and neurological disease modeling, 3D living objects cannot be studied easily using conventional approaches to neuromodulation, sensing, and manipulation. Here, we introduce classes of microfabricated 3D frameworks as compliant, multifunctional neural interfaces to spheroids and to assembloids. Electrical, optical, chemical, and thermal interfaces to cortical spheroids demonstrate some of the capabilities. Complex architectures and high-resolution features highlight the design versatility. Detailed studies of the spreading of coordinated bursting events across the surface of an isolated cortical spheroid and of the cascade of processes associated with formation and regrowth of bridging tissues across a pair of such spheroids represent two of the many opportunities in basic neuroscience research enabled by these platforms
In Vitro Evaluation of Enterococcus faecalis Adhesion on Various Endodontic Medicaments
E. faecalis in endodontic infection represents a biofilm type of disease, which explains the bacteriaâs resistance to various antimicrobial compounds and the subsequent failure after endodontic treatment. The purpose of this study was to compare antimicrobial activities and bacteria kinetic adhesion in vitro for three endodontic medicaments with a clinical isolate of E. faecalis. We devised a shake culture which contained the following intracanalar preparations: CPD, Endoidrox (EIX), PulpCanalSealer (PCS); these were immersed in a liquid culture medium inoculated with the microorganism. The shake system velocity was able to prevent non-specific bacteria adhesion and simulated the salivary flow. Specimens were collected daily (from both the medium and medicaments) for 10 days; the viable cells were counted by plate count, while the adhesion index AI° [E. faecalis fg DNA] /mm2 was evaluated in the pastes after DNA extraction, by quantitative real time PCR for the 16S rRNA gene. A partial growth inhibition, during the first 24 hours, was observed in the liquid medium and on the medicaments for EIX and subsequently for CPD (six logs). EIX showed the lowest adhesion coefficient (5*102 [fg DNA]/mm2) for nine days and was similar to the control. PCS showed no antimicrobial/antibiofilm properties. This showed that âcalcium oxideâ base compounds could be active against biofilm progression and at least in the short term (2-4 days) on E. faecalis cells growing in planktonic cultures
- âŠ