659 research outputs found
Precursors of an upcoming solar cycle at high latitudes from coronal green line data
After reviewing potential early indicators of an upcoming solar cycle at high
latitudes, we focus attention on the rush-to-the-poles (RTTP) phenomenon in
coronal green line emission. Considering various correlations between
properties of the RTTP with the upcoming solar cycle we find a correlation
between the rate of the RTTP and the time delay until the maximum of the next
solar cycle. On the basis of this correlation and the known internal
regularities of the sunspot number series we predict that, following a minimum
in 2019, cycle 25 will peak in late 2024 at an amplitude of about 130 (in terms
of smoothed monthly revised sunspot numbers). This slightly exceeds the
amplitude of cycle 24 but it would still make cycle 25 a fairly weak cycle.Comment: 17 pages, 5 figures J. Atm. Sol.-Terr. Phys., in pres
Evidence for fresh frost layer on the bare nucleus of comet Hale--Bopp at 32 AU distance
Here we report that the activity of comet Hale--Bopp ceased between late 2007
and March, 2009, at about 28 AU distance from the Sun. At that time the comet
resided at a distance from the Sun that exceeded the freeze-out distance of
regular comets by an order of magnitude. A Herschel Space Observatory PACS scan
was taken in mid-2010, in the already inactive state of the nucleus. The albedo
has been found to be surprisingly large (8.10.9%{}), which exceeds the
value known for any other comets. With re-reduction of archive HST images from
1995 and 1996, we confirm that the pre-perihelion albedo resembled that of an
ordinary comet, and was smaller by a factor of two than the post-activity
albedo. Our further observations with the Very Large Telescope (VLT) also
confirmed that the albedo increased significantly by the end of the activity.
We explain these observations by proposing gravitational redeposition of icy
grains towards the end of the activity. This is plausible for such a massive
body in a cold environment, where gas velocity is lowered to the range of the
escape velocity. These observations also show that giant comets are not just
the upscaled versions of the comets we know but can be affected by processes
that are yet to be fully identified.Comment: 7 pages, 6 figures, accepted for publication in Ap
The antiepileptic potential of nucleosides
Despite newly developed antiepileptic drugs to suppress epileptic symptoms, approximately one third of patients remain drug refractory. Consequently, there is an urgent need to develop more effective therapeutic approaches to treat epilepsy. A great deal of evidence suggests that endogenous nucleosides, such as adenosine (Ado), guanosine (Guo), inosine (Ino) and uridine (Urd), participate in the regulation of pathomechanisms of epilepsy. Adenosine and its analogues, together with non-adenosine (non-Ado) nucleosides (e.g., Guo, Ino and Urd), have shown antiseizure activity. Adenosine kinase (ADK) inhibitors, Ado uptake inhibitors and Ado-releasing implants also have beneficial effects on epileptic seizures. These results suggest that nucleosides and their analogues, in addition to other modulators of the nucleoside system, could provide a new opportunity for the treatment of different types of epilepsies. Therefore, the aim of this review article is to summarize our present knowledge about the nucleoside system as a promising target in the treatment of epilepsy
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