Prominent Knots Research Articles

Structural characteristics of theStreptomycesbacteriophage φC31

Some structural characteristics of the Streptomyces phage φC31 were analyzed. A simpler and at least 50 times more efficient method than those previously described for isolating the phage is reported. The phage is naked, showing a polyhedral head 53 nm wide, a long non-contractile tail 100 × 5 nm, a basal plate 15 nm in diameter with at least one pin, and a prominent knot between the head and the tail. Up to 17 polypeptides had been found in the virion. Four of them, of 51, 38.5, 29.5 and 28 kDa, make up around 84% of the total protein of the particle.

Motions in a loop prominence

Motions of loop prominence knots have been studied on Hα-line filtergrams. By making use of contours of equal photographic density for entire cinegram it has been possible to significantly decrease the error in determining the locations of the knots. The method of mean velocities has been developed, which has permitted for the first time accurate determination of the laws of knot motion with sufficient accuracy. Two types of falling knots are distinguished: (1) those with a constant acceleration that is always below the gravitational acceleration, and (2) those with a constant velocity. The initial velocity of the falling knots is always different from zero. The gasdynamic theory has been developed to explain the deceleration of the two types of knots due to: the work done against the pressure force; pileup plasma raking; and shock-wave generation. The shock mechanism imparts a constant velocity to the motion. The temperature along the knot trajectories has been estimated. The ratio of the densities in the knots to the surrounding medium has been found.

Constituents and Causes of Emotion and Action

to regard one occurrence as part -a component-of a broader episode or state. Here is an uncontroversial and hence uninteresting case. When you go out for exercise this morning, each stride you take is part of your two-mile hike. Yet nobody would imagine that the steps you took were causes of your hiking. Naturally your strides did have effects. They produced your fatigue and your footprints. And your hiking might have resulted from your encounter with a friend who persuaded or compelled you to engage in that form of exercise. My inquiry is sparked off by more than metaphysical curiosity about such trifling examples. I believe my distinction will help us cut through four prominent knots in contemporary philosophy of mind. The first one, which has been debated least, has to do with the hook-up between your emotion and the thinking upon which your emotion is based. The second enigma is the much discussed connection between your deeds and your reasons for acting. In both these cases philosophical opinion is sharply divided (see Appendix). Some writers insist that the occurrences in question must be causally linked. Others, whom I dub entailment theorists , maintain that the bonds are logical. My analysis may ruffle both parties, since I hold that the paired events are neither causally nor logically connected. My thesis is that thinking is an element of emotion, and that reasons are ingredients of what we do for reasons. To causal theorists I offer the consolation that various events which constitute emotion and action may be causally interrelated. Entailment theorists should be comforted by my

Prominences in active regions

As an interplay of plasma and magnetic field the solar prominences represent a nice example of cosmical hydromagnetics. Due to stronger magnetic fields in active regions the prominence processes are more violent there than in non-active regions. Observing with a coronagraph or watching prominence movies one recognizes some characteristic processes in prominences of active regions: (a)Condensation of Hα material in coronal space without any direct observational evidence of the material supply. It seems that the material had been ejected in the form of corpuscular radiation, captured, thermalized and cooled down to 104 °K, when it becomes observable in the Hα line.(b)Dissolution of the Hα material. Knots, streamers of sprays, surges and puffs often undergo a reverse process: they dissolve and disappear when observed in Hα. Similar dissolution is typical for a great part of the material in eruptive prominences.(c)Spiraling motion and detwisting of streamers are observed in surges, sprays, funnels and also in eruptive prominences. In the prominence movies of HAO Boulder, Sacramento Peak Observatory and Pic-du-Midi we have found many nice examples. In most cases (if not in all) the detwisting resulted in a marked simplification of the prominence structure.(d)Emerging magnetic fields may be seen in form of small rising and expanding Hα loops (velocities about 50 km/sec). In this type of loops the material is dragged out of the chromosphere. A similar process with low velocities has been observed in 5303 Å movies of coronal condensations.(e)Capture of a surge by transversal magnetic fields has been observed and photographed on October 7, 1956. Surge material has been captured in a complex loopy structure and then streamed sunwards along the loops. This event shows that capturing of plasma streamers by transversal magnetic fields does occur on the Sun and that the material supply for AS prominences (see item (a)) would thus be possible.(f)Collisional processes occur in different forms. One has been just described in item (e). However, the well-known prominence of Lyot from 1937 shows that a surge hits a prominence without being (completely) captured. The prominence which has been hit decays and the surge material seems to be reflected (at least partly) downwards. Two colliding knots may bypass each other in complicated trajectories. Cases have been recorded of falling prominence knots being stopped and accelerated upwards, with measured acceleration more than 10 solar g.(g)Oscillating prominences at the limb have been photographed. The oscillations followed shortly after a nearby flare-spray event. This may be the counterpart of the disk phenomenon discovered by astronomers of Lockheed Observatory.