497 research outputs found
Dietary Strategies to Optimize Wound Healing after Periodontal and Dental Implant Surgery: An Evidence-Based Review
Methods to optimize healing through dietary strategies present an attractive option for patients, such that healing
from delicate oral surgeries occurs as optimally as possible with minimal patient-meditated complications through improper
food choices. This review discusses findings from studies that have investigated the role of diet, either whole foods
or individual dietary components, on periodontal health and their potential role in wound healing after periodontal surgery.
To date, research in this area has largely focused on foods or individual dietary components that may attenuate inflammation
or oxidant stress, or foster de novo bone formation. These studies suggest that a wide variety of dietary components,
including macronutrients and micronutrients, are integral for optimal periodontal health and have the potential to
accelerate oral wound healing after periodontal procedures. Moreover, this review provides guidance regarding dietary
considerations that may help a patient achieve the best possible outcome after a periodontal procedure
Contending cultures of counterterrorism: transatlantic divergence or convergence?
Terrorist attacks on the United States, Spain and the United Kingdom have underlined the differing responses of Europe and the United States to the 'new terrorism'. This article analyses these responses through the prism of historically determined strategic cultures. For the last four years the United States has directed the full resources of a 'national security' approach towards this threat and has emphasized unilateralism. Europe, based on its own past experience of terrorism, has adopted a regulatory approach pursued through multilateralism. These divergences in transatlantic approaches, with potentially major implications for the future of the relationship, have appeared to be mitigated by a revised American strategy of counterterrorism that has emerged during 2005. However, this article contends that while strategic doctrines may change, the more immutable nature of strategic culture will make convergence difficult. This problem will be compounded by the fact that neither Europe nor America have yet addressed the deeper connections between terrorism and the process of globalization
Are Supershells Powered by Multiple Supernovae? Modeling the Radio Pulsar Population Produced by OB Associations
Traditional searches for radio pulsars have targeted individual small regions
such as supernova remnants or globular clusters, or have covered large
contiguous regions of the sky. None of these searches has been specifically
directed towards giant supershells, some of which are likely to have been
produced by multiple supernova (SN) explosions from an OB association. Here we
perform a Montecarlo simulation of the pulsar population associated with
supershells powered by multiple SNe. We predict that several tens of radio
pulsars could be detected with current instruments associated with the largest
Galactic supershells (with kinetic energies >~ 10^{53} ergs), and a few pulsars
with the smaller ones. We test these predictions for some of the supershells
which lie in regions covered by past pulsar surveys. For the smaller
supershells, our results are consistent with the few detected pulsars per
bubble. For the giant supershell GSH 242-03+37, we find the multiple SN
hypothesis inconsistent with current data at the 95% level. We stress the
importance of undertaking deep pulsar surveys in correlation with supershells.
Failure to detect any pulsar enhancement in the largest of them would put
serious constraints on the multiple SN origin for them. Conversely, the
discovery of the pulsar population associated with a supershell would allow a
different/independent approach to the study of pulsar properties.Comment: accepted to ApJ; 17 pages, 2 figures, 1 tabl
Oil Recovery in Low Temperature and Salinity Reservoir Rock Using Anionic and Anionic/Cationic Surfactant Formulations
As oil reserves are being depleted in the United States, there is an increasing need to recover the trapped oil in the reservoir rock which accounts for up to 60% of the total oil available. This oil may be recovered using chemical enhanced oil recovery (EOR) techniques. In our case study, we investigated viable EOR surfactant/polymer formulations for conditions conducive to high efficiency oil recovery in ultra-low salinity, low temperature, and high hardness reservoirs. Formulations were screened for Winsor Phase I (microemulsions) or Winsor Phase III (bicontinuous emulsions),: both of which are conducive to high efficiency oil recovery. Strong emulsion phase behavior at low salinities was observed in binary surfactant mixtures of anionic alkyl-alkoxy sulfates (at \u3e 16,000 ppm). Using a novel anionic/cationic formulation, emulsion phase behavior was observed at the ultra-low reservoir salinity of 10,000 ppm. These formulations demonstrate industrially viable surfactant/polymer formulations that can used for high efficiency EOR in low temperature-salinity and high hardness reservoirs within the continental United States and abroad
Optimal Surfactant Selection for Chemical Enhanced Oil Recovery in Low Temperature, Low Salinity, High Hardness Reservoirs
Based on the environmental properties of a crude oil reservoir, only 20-30 % of oil product can be recovered using primary and secondary extraction methods. The remaining stranded oil can only be recovered via various enhanced oil recovery methods. Chemical enhanced oil recovery (EOR) uses specialty chemicals to extract trapped oil in rock layers by generating in-situ microemulsion in the presence of reservoir brine and oil. In this case study, phase behavior tests are conducted for microemulsion formation between the surfactant solution and the oil. The phase behavior tests model reservoirs with low temperature and low salinity. In order to narrow the selection of surfactants for testing, phase behavior tests and interfacial tension experiments were used to determine the equivalent alkane carbon number (EACN) of the oil in this reservoir. Along with phase testing, extensive interfacial tension measurements were carried out with the model oil and the reservoir fluid at various salinities. The reservoir sample oil was determined to have an EACN of around 12, which effectively models the hydrocarbon part of the multicomponent crude oil similar to a dodecane system. These results facilitate in method development for EACN determination and in the selection of the surfactants that will create optimum emulsion for high efficiency oil recovery in low temperature and low salinity reservoirs typical to the Illinois basin in the United States
The Pioneer Anomaly
Radio-metric Doppler tracking data received from the Pioneer 10 and 11
spacecraft from heliocentric distances of 20-70 AU has consistently indicated
the presence of a small, anomalous, blue-shifted frequency drift uniformly
changing with a rate of ~6 x 10^{-9} Hz/s. Ultimately, the drift was
interpreted as a constant sunward deceleration of each particular spacecraft at
the level of a_P = (8.74 +/- 1.33) x 10^{-10} m/s^2. This apparent violation of
the Newton's gravitational inverse-square law has become known as the Pioneer
anomaly; the nature of this anomaly remains unexplained. In this review, we
summarize the current knowledge of the physical properties of the anomaly and
the conditions that led to its detection and characterization. We review
various mechanisms proposed to explain the anomaly and discuss the current
state of efforts to determine its nature. A comprehensive new investigation of
the anomalous behavior of the two Pioneers has begun recently. The new efforts
rely on the much-extended set of radio-metric Doppler data for both spacecraft
in conjunction with the newly available complete record of their telemetry
files and a large archive of original project documentation. As the new study
is yet to report its findings, this review provides the necessary background
for the new results to appear in the near future. In particular, we provide a
significant amount of information on the design, operations and behavior of the
two Pioneers during their entire missions, including descriptions of various
data formats and techniques used for their navigation and radio-science data
analysis. As most of this information was recovered relatively recently, it was
not used in the previous studies of the Pioneer anomaly, but it is critical for
the new investigation.Comment: 165 pages, 40 figures, 16 tables; accepted for publication in Living
Reviews in Relativit
Dietary Strategies to Optimize Wound Healing after Periodontal and Dental Implant Surgery: An Evidence-Based Review
Methods to optimize healing through dietary strategies present an attractive option for patients, such that healing
from delicate oral surgeries occurs as optimally as possible with minimal patient-meditated complications through improper
food choices. This review discusses findings from studies that have investigated the role of diet, either whole foods
or individual dietary components, on periodontal health and their potential role in wound healing after periodontal surgery.
To date, research in this area has largely focused on foods or individual dietary components that may attenuate inflammation
or oxidant stress, or foster de novo bone formation. These studies suggest that a wide variety of dietary components,
including macronutrients and micronutrients, are integral for optimal periodontal health and have the potential to
accelerate oral wound healing after periodontal procedures. Moreover, this review provides guidance regarding dietary
considerations that may help a patient achieve the best possible outcome after a periodontal procedure
Serendipitous discovery of a dying Giant Radio Galaxy associated with NGC 1534, using the Murchison Widefield Array
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Recent observations with the Murchison Widefield Array at 185~MHz have serendipitously unveiled a heretofore unknown giant and relatively nearby () radio galaxy associated with NGC\,1534. The diffuse emission presented here is the first indication that NGC\,1534 is one of a rare class of objects (along with NGC\,5128 and NGC\,612) in which a galaxy with a prominent dust lane hosts radio emission on scales of 700\,kpc. We present details of the radio emission along with a detailed comparison with other radio galaxies with disks. NGC1534 is the lowest surface brightness radio galaxy known with an estimated scaled 1.4-GHz surface brightness of just 0.2\,mJy\,arcmin. The radio lobes have one of the steepest spectral indices yet observed: , and the core to lobe luminosity ratio is $Peer reviewe
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