8,989 research outputs found
PKI Interoperability: Still an Issue? A Solution in the X. 509 Realm
There exist many obstacles that slow the global adoption of public key infrastructure (PKI) technology. The PKI interoperability problem, being poorly understood, is one of the most confusing. In this paper, we clarify the PKI interoperability issue by exploring both the juridical and technical domains. We demonstrate the origin of the PKI interoperability problem by determining its root causes, the latter being legal, organizational and technical differences between countries, which mean that relying parties have no one to rely on. We explain how difficult it is to harmonize them. Finally, we propose to handle the interoperability problem from the trust management point of view, by introducing the role of a trust broker which is in charge of helping relying parties make informed decisions about X.509 certificates
5-HT6R Viral Vector-Mediated Indirect Pathway Activation in the Dorsolateral Striatum: A Discussion on Basal Ganglia Habitual and Goal-Directed Circuits
Altering maladaptive behavioral tendencies is relevant for clinical interventions, making research on underlying mechanisms of habit essential. Mechanisms of habit are explored here with differential activation of the indirect pathway in the basal ganglia. Viral vector-mediated overexpression of the 5-hydroxytryptamine 6 (5-HT6) receptor in the indirect pathway of the dorsolateral striatum was used to increase indirect pathway activity. Subjects were trained such that control animals were expected to exhibit habitual behavior. We hypothesized increased activation of the indirect pathway would maintain goal-directed behavior. To test this hypothesis female rats were assigned to 5-HT6 receptor upregulation or control groups in a reward devaluation behavior paradigm to assess habitual behavior. Although our results do not show anticipated behavioral results following reward devaluation, a lack of statistical power due to small sample sizes does not allow conclusions to be reached
The association of shift work and coronary heart disease risk factors among male factory workers in Kota Bharu, Kelantan
Shift work is one of the work hour systems in which a relay of employees extends the period of production beyond the conventional 8-hour working day. It has been found to be associated with various health problems and there is concern that shift workers are at higher risk to develop risk factors for coronary heart disease (CHD). The study was undertaken to examine relationships between shift work and CHD risk factors, namely hypertension, dyslipidaemia (either hypercholesterolaemia, hyper-low density lipoprotein-cholesterolaemia, hypo-high density lipoprotein-cholesterolaemia or hypertriglyceridaemia), high body mass index (BMI), hyperglycemia and physical inactivity among male factory workers in a factory in Kota Bharu, Kelantan. METHODS: This study was a contrived cross-sectional study of 76 shift and 72 day workers from one ofthe factories in Kota Bharu, Kelantan. Data was collected through a questionnaire on psychosocial and life-style factors, anthropometric and blood pressure measurement, fasting blood sugar and fasting lipid proJiles analyses. RESULTS: The prevalence of hypertension, hypercholesterolaemia, hypertriglyceridaemia and high body mass index (BMO were significantly higher among shift workers compared to day workers. There was no difference in the prevalence of hyperg[ycemia, hypo-high-density lipoprotein-cholesterolaemia, hyper-high-density lipoprotein-cholesterolaemia and physical inactivity. When the shiji workers were compared with the day workers, the aajusted odds ratio (OR) for hypertension, high BMI andphysical inactivity were 9.1 (95% CI 1.4-56.8), 2.9 (95% CI 1.3-6.1) and 7.7 (95% CI 2.1-27.5) respectively. There was neither association of shift work with dyslipidaemia, nor with hyperglycemia. CONCLUSIONS: There were positive association between shiji work and hypertension, high BMI andphysical inactivity which denotes a higher risk of CHD risk factors among shift workers compared to day workers
An existential-phenomenological investigation of the experience of being accepted in individuals who have undergone psychiatric institutionalization
This study represents an existential-phenomenological investigation of the experience of being accepted in individuals who have undergone psychiatric institutionalization. Written protocols of narrative accounts were collected from nine individuals drawn from a partial hospitalization programme, with the analysis of these narratives revealing seven basic constituents of the focal experience. The paper concludes with a discussion of the clinical implications of these findings for understanding this experience as it relates to psychotherapy with individuals who experience severe mental illness symptoms and/or stigma
The spin-orbit angle of the transiting hot jupiter CoRoT-1b
We measure the angle between the planetary orbit and the stellar rotation
axis in the transiting planetary system CoRoT-1, with new HIRES/Keck and
FORS/VLT high-accuracy photometry. The data indicate a highly tilted system,
with a projected spin-orbit angle lambda = 77 +- 11 degrees. Systematic
uncertainties in the radial velocity data could cause the actual errors to be
larger by an unknown amount, and this result needs to be confirmed with further
high-accuracy spectroscopic transit measurements.
Spin-orbit alignment has now been measured in a dozen extra-solar planetary
systems, and several show strong misalignment. The first three misaligned
planets were all much more massive than Jupiter and followed eccentric orbits.
CoRoT-1, however, is a jovian-mass close-in planet on a circular orbit. If its
strong misalignment is confirmed, it would break this pattern. The high
occurence of misaligned systems for several types of planets and orbits favours
planet-planet scattering as a mechanism to bring gas giants on very close
orbits.Comment: to appear in in MNRAS letters [5 pages
The central image of a gravitationally lensed quasar
A galaxy can act as a gravitational lens, producing multiple images of a
background object. Theory predicts there should be an odd number of images but,
paradoxically, almost all observed lenses have 2 or 4 images. The missing image
should be faint and appear near the galaxy's center. These ``central images''
have long been sought as probes of galactic cores too distant to resolve with
ordinary observations. There are five candidates, but in one case the third
image is not necessarily a central image, and in the others, the central
component might be a foreground source rather than a lensed image. Here we
report the most secure identification of a central image, based on radio
observations of PMN J1632-0033, one of the latter candidates. Lens models
incorporating the central image show that the mass of the lens galaxy's central
black hole is less than 2 x 10^8 M_sun, and the galaxy's surface density at the
location of the central image is more than 20,000 M_sun per square parsec, in
agreement with expectations based on observations of galaxies hundreds of times
closer to the Earth.Comment: Nature, in press [7 pp, 2 figs]. Standard media embargo applies
before publicatio
Consensus Message Passing for Layered Graphical Models
Generative models provide a powerful framework for probabilistic reasoning.
However, in many domains their use has been hampered by the practical
difficulties of inference. This is particularly the case in computer vision,
where models of the imaging process tend to be large, loopy and layered. For
this reason bottom-up conditional models have traditionally dominated in such
domains. We find that widely-used, general-purpose message passing inference
algorithms such as Expectation Propagation (EP) and Variational Message Passing
(VMP) fail on the simplest of vision models. With these models in mind, we
introduce a modification to message passing that learns to exploit their
layered structure by passing 'consensus' messages that guide inference towards
good solutions. Experiments on a variety of problems show that the proposed
technique leads to significantly more accurate inference results, not only when
compared to standard EP and VMP, but also when compared to competitive
bottom-up conditional models.Comment: Appearing in Proceedings of the 18th International Conference on
Artificial Intelligence and Statistics (AISTATS) 201
Twenty-One New Light Curves of OGLE-TR-56b: New System Parameters and Limits on Timing Variations
Although OGLE-TR-56b was the second transiting exoplanet discovered, only one
light curve, observed in 2006, has been published besides the discovery data.
We present twenty-one light curves of nineteen different transits observed
between July 2003 and July 2009 with the Magellan Telescopes and Gemini South.
The combined analysis of the new light curves confirms a slightly inflated
planetary radius relative to model predictions, with R_p = 1.378 +/- 0.090 R_J.
However, the values found for the transit duration, semimajor axis, and
inclination values differ significantly from the previous result, likely due to
systematic errors. The new semimajor axis and inclination, a = 0.01942 +/-
0.00015 AU and i = 73.72 +/- 0.18 degrees, are smaller than previously
reported, while the total duration, T_14 = 7931 +/- 38 s, is 18 minutes longer.
The transit midtimes have errors from 23 s to several minutes, and no evidence
is seen for transit midtime or duration variations. Similarly, no change is
seen in the orbital period, implying a nominal stellar tidal decay factor of
Q_* = 10^7, with a three-sigma lower limit of 10^5.7.Comment: 14 pages, 5 figures, accepted to Ap
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