74 research outputs found
Using Early Data to Illuminate the Pioneer Anomaly
Analysis of the radio tracking data from the Pioneer 10/11 spacecraft at
distances between about 20 - 70 AU from the Sun has consistently indicated the
presence of an unmodeled, small, constant, Doppler blue shift drift of order 6
\times 10^{-9} Hz/s. After accounting for systematics, this drift can be
interpreted as a constant acceleration of a_P= (8.74 \pm 1.33) \times 10^{-8}
cm/s^2 directed towards the Sun, or perhaps as a time acceleration of a_t =
(2.92 \pm 0.44)\times 10^{-18} s/s^2. Although it is suspected that there is a
systematic origin to this anomaly, none has been unambiguously demonstrated. We
review the current status of the anomaly, and then point out how the analysis
of early data, which was never analyzed in detail, could allow a more clear
understanding of the origin of the anomaly, be it a systematic or a
manifestation of unsuspected physics.Comment: 19 pages, 6 figures, 2 tables, additional materia
Mutations in the uncE gene affecting assembly of the c-subunit of the adenosine triphosphatase of Escherichia coli
The F1F0-ATPase of Escherichia coli. Substitution of proline by leucine at position 64 in the c-subunit causes loss of oxidative phosphorylation
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
Carotid ultrasound is useful for the cardiovascular risk stratification in patients with hidradenitis suppurativa
INTRODUCTION: Hidradenitis suppurativa (HS) is a chronic inflammatory cutaneous disease which has been associated with an increased risk of adverse cardiovascular (CV) outcomes. Adequate stratification of the CV risk is an issue of major importance in patients with HS. To analyze the usefulness of carotid ultrasound (US) assessment for the CV disease risk stratification compared with a traditional score, the Framingham risk score (FRS), in a series of patients with HS.
METHODS:
Cross-sectional study of 60 patients with HS without history of CV events, diabetes mellitus or chronic kidney disease. Information on CV risk factors was collected and the FRS was calculated. Thus, the patients were classified into low, intermediate and high-CV disease risk categories based on FRS. Carotid US was performed in all participants, and the presence of atherosclerotic plaques was considered as a marker of high CV risk.
RESULTS:
HS patients had a mean age of 45.1±10.2 years, and 55% were female. The median FRS was 5.7 (IQR: 3.1-14.7). Twenty-four (40%) of the patients were classified into the low risk group, 28 (46.7%) in the intermediate risk group, and 8 (13.3%) into the FRS-high risk category. Noteworthy, carotid US revealed that about one-third of the patients (17/52; 32.6%) in the FRS-based low and intermediate risk categories had carotid plaques, and, therefore, they were reclassified into a high-risk category.
CONCLUSION:
CV risk in HS patients may be underestimated by using the FRS. Carotid US may be useful to improve the CV risk stratification of patients with HS.This study was funded through an unrestricted grant provided by AbbVie to MGL. AbbVie has not played any role in study design, data collection and analysis, decision to publish or preparation of the manuscript
Probiotic Bacteria Induce a ‘Glow of Health’
Radiant skin and hair are universally recognized as indications of good health. However, this ‘glow of health’ display remains poorly understood. We found that feeding of probiotic bacteria to aged mice induced integumentary changes mimicking peak health and reproductive fitness characteristic of much younger animals. Eating probiotic yogurt triggered epithelial follicular anagen-phase shift with sebocytogenesis resulting in thick lustrous fur due to a bacteria-triggered interleukin-10-dependent mechanism. Aged male animals eating probiotics exhibited increased subcuticular folliculogenesis, when compared with matched controls, yielding luxuriant fur only in probiotic-fed subjects. Female animals displayed probiotic-induced hyperacidity coinciding with shinier hair, a feature that also aligns with fertility in human females. Together these data provide insights into mammalian evolution and novel strategies for integumentary health
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