Can the flyby anomaly be attributed to earth-bound dark matter?

We make preliminary estimates to assess whether the recently reported flyby anomaly can be attributed to dark matter interactions. We consider both elastic and exothermic inelastic scattering from dark matter constituents; for isotropic dark matter velocity distributions, the former decrease, while the latter increase, the final flyby velocity. The fact that the observed flyby velocity anomaly shows examples with both positive and negative signs, requires the dominance of different dark matter scattering processes along different flyby trajectories. The magnitude of the observed anomalies requires dark matter densities many orders of magnitude greater than the galactic halo density. Such a large density could result from an accumulation cascade, in which the solar system-bound dark matter density is much higher than the galactic halo density, and the earth-bound density is much higher than the solar system-bound density. We discuss a number of strong constraints on the hypothesis of a dark matter explanation for the flyby anomaly. These require dark matter to be non-self-annihilating, with the dark matter scattering cross section on nucleons much larger, and the dark matter mass much lighter, than usually assumed.Comment: Latex, 21 pages. v3: substantially revised and expanded; v4: version to appear in Phys. Rev.

Squeezed gluon vacuum and the global colour model of QCD

We discuss how the vacuum model of Celenza and Shakin with a squeezed gluon condensate can explain the existence of an infrared singular gluon propagator frequently used in calculations within the global colour model. In particular, it reproduces a recently proposed QCD-motivated model where low energy chiral parameters were computed as a function of a dynamically generated gluon mass. We show how the strength of the confining interaction of this gluon propagator and the value of the physical gluon condensate may be connected.Comment: 13 pages, LaTe

Gathering experience in trust-based interactions

As advances in mobile and embedded technologies coupled with progress in adhoc networking fuel the shift towards ubiquitous computing systems it is becoming increasingly clear that security is a major concern. While this is true of all computing paradigms, the characteristics of ubiquitous systems amplify this concern by promoting spontaneous interaction between diverse heterogeneous entities across administrative boundaries [5]. Entities cannot therefore rely on a specific control authority and will have no global view of the state of the system. To facilitate collaboration with unfamiliar counterparts therefore requires that an entity takes a proactive approach to self-protection. We conjecture that trust management is the best way to provide support for such self-protection measures

Explorer 12 magnetometer records, 16 August - 6 December 1961

Explorer XII magnetometer record

Can a Logarithmically Running Coupling Mimic a String Tension?

It is shown that a Coulomb potential using a running coupling slightly modified from the perturbative form can produce an interquark potential that appears nearly linear over a large distance range. Recent high-statistics SU(2) lattice gauge theory data fit well to this potential without the need for a linear string-tension term. This calls into question the accuracy of string tension measurements which are based on the assumption of a constant coefficient for the Coulomb term. It also opens up the possibility of obtaining an effectively confining potential from gluon exchange alone.Comment: 13 pages, LaTeX, two figures not included, available from author. revision - Line lengths fixed so it will tex properl

Vacuum Condensates in the Global Color Symmetry Model

Based on the quark propagator in the instanton dilute liquid approximation, we calculate analytically the quark condensate , the mixed quark gluon condensate $g_{s}$ and the four quark condensate at the mean field level in the framework of global color symmetry model. The numerical calculation shows that the values of these condensates are compatible with the ranges determined by other nonperturbative approaches. Moreover, we find that for nonlocal four quark condensate the previous vacuum saturation assumption is not a good approximation even at the mean field level.Comment: 8 latex pages, no figure, Submitted to Phys. Rev.

From treebank resources to LFG F-structures

We present two methods for automatically annotating treebank resources with functional structures. Both methods define systematic patterns of correspondence between partial PS configurations and functional structures. These are applied to PS rules extracted from treebanks, or directly to constraint set encodings of treebank PS trees

Risk of neuropsychiatric and cardiovascular adverse events following treatment with varenicline and nicotine replacement therapy in the UK Clinical Practice Research Datalink:a case-crossover study

BACKGROUND AND AIMS: Varenicline and nicotine replacement therapy (NRT) are the most commonly used medications to quit smoking. Given their widespread use, monitoring adverse risks remains important. This study aimed to estimate the neuropsychiatric and cardiovascular risks associated with varenicline and NRT as used in routine UK care.DESIGN: Case crossover study.SETTING: UK based electronic primary care records in the Clinical Practice Research Datalink from 2006 to 2015 linked to hospital and mortality datasets.PARTICIPANTS: Adult smokers (n=?) observed in periods when exposed and not exposed to either varenicline or NRT.MEASUREMENTS: Main outcomes included suicide, self-harm, myocardial infarction (MI), all-cause death and cause-specific death (MI, chronic obstructive pulmonary disease (COPD)). In primary analyses, conditional logistic regression was used to compare the chance of varenicline or NRT exposure in the risk period (90 days prior to the event) with the chance of exposure in an earlier single reference period (91-180 days prior to the event) or multiple 90-day reference periods to increase statistical power.FINDINGS: In the primary analyses, findings were inconclusive for the associations between varenicline and the main outcomes using a single reference period, whilst NRT was associated with MI (Odds ratio (OR) 1.40, 95% Confidence interval (CI) 1.18-1.67). Using multiple reference periods, varenicline was associated with an increased risk of self-harm (OR 1.32, 95% CI 1.12-1.56) and suicide (OR 3.56, 95% CI 1.32-9.60) but a reduction in all-cause death (OR 0.75, 95% CI 0.61-0.93). NRT was associated with MI (OR 1.54, 95% CI 1.36-1.74), self-harm (OR 1.30, 95% CI 1.18-1.44), and deaths from MI (OR 1.53, 95% CI 1.11-2.10), COPD (OR 1.33, 95% CI 1.14-1.56) and all causes (OR 1.28, 95% CI 1.18-1.40) when using multiple reference periods.CONCLUSIONS: There appear to be positive associations between 1) nicotine replacement therapy (NRT) and myocardial infarction, death, and risk of self-harm and 2) varenicline and increased risk of self-harm and suicide, as well as a negative association between varenicline and all-cause death. The associations may not be causal. They may reflect health changes at the time of smoking cessation (NRT is prescribed for people with cardiac problems) or be associated with quit attempts (exposure to both medicines was associated with self-harm).</p