Transient Zitterbewegung of charge carriers in graphene and carbon nanotubes

Observable effects due to trembling motion (Zitterbewegung, ZB) of charge carriers in bilayer graphene, monolayer graphene and carbon nanotubes are calculated. It is shown that, when the charge carriers are prepared in the form of gaussian wave packets, the ZB has a transient character with the decay time of femtoseconds in graphene and picoseconds in nanotubes. Analytical results for bilayer graphene allow us to investigate phenomena which accompany the trembling motion. In particular, it is shown that the transient character of ZB in graphene is due to the fact that wave subpackets related to positive and negative electron energies move in opposite directions, so their overlap diminishes with time. This behavior is analogous to that of the wave packets representing relativistic electrons in a vacuum.Comment: 7 pages, 3 figures, augmented versio

The Religious Thereads and Biblical Figures in the Astronomical Treatise of Jan of Głogów (1445–1507)

The article offers insights on the reception and literary transmission of the religious and biblical threads running through the astronomical treatise Introductorium compendiosum in Tractatum sphaerae materialis Ioannis de Sacrobusto of Jan of Głogów. As a narrative and historical book, the Bible offered a broad market for tales in both oral and written form and apocryphal works of fiction, which were adopted and adapted in Jan’s dissertation in order to meet the scientific tasks and expectations of young listeners, thus making the practical realization of the scholastic educational standards and needs. Among others, the article examines in Jan’s treatise popular biblical tales, such as Adam and Eve, Moses, Noah, Abraham, and Jerusalem and the Hell together with their geographical and astronomical features. The history of Pontius Pilatus is also discussed with his alleged German descent. This combination of such disparate narrative and research material shows both the wealth of Jan’s storytelling and his ability to teach astronomy

Wątki iberyjskie w astronomicznym traktacie Jana z Głogowa (1445–1507)

The article offers an analysis of the reception of Iberian threads running through the astronomical treatise Introductorium compendiosum in Tractatum sphaerae materialis Ioannis de Sacrobusto of Jan of Głogów by applying a literary analysis of the research text. The author of the article hints at the paradoxical symbol of the Iberian countries, which were regarded both as being at the end of the world from the times of the Greeks and Romans as well as a base or starting point from which the great transatlantic voyages were begun to discover new lands and continents. The reader is also given an insight into the achievements of scholars such as Isidorus Hispalensis (the Bishop of Seville), Paulus Orosius and Averroes, who were descended from the Iberian peninsula and had an effect or influence on Jan’s dissertation

Conduction electrons localized by charged magneto-acceptors A2−^{2-} in GaAs/GaAlAs quantum wells

A variational theory is presented of A$^{1-}$ and A$^{2-}$ centers, i.e. of a negative acceptor ion localizing one and two conduction electrons, respectively, in a GaAs/GaAlAs quantum well in the presence of a magnetic field parallel to the growth direction. A combined effect of the well and magnetic field confines conduction electrons to the proximity of the ion, resulting in discrete repulsive energies above the corresponding Landau levels. The theory is motivated by our experimental magneto-transport results which indicate that, in a heterostructure doped in the GaAs well with Be acceptors, one observes a boil-off effect in which the conduction electrons in the crossed-field configuration are pushed by the Hall electric field from the delocalized Landau states to the localized acceptor states and cease to conduct. A detailed analysis of the transport data shows that, at high magnetic fields, there are almost no conducting electrons left in the sample. It is concluded that one negative acceptor ion localizes up to four conduction electrons.Comment: 8 pages, 5 figure

A Novel Reporter Mouse Uncovers Endogenous Brn3b Expression.

Brn3b (Pou4f2) is a class-4 POU domain transcription factor known to play central roles in the development of different neuronal populations of the Central Nervous System, including retinal ganglion cells (RGCs), the neurons that connect the retina with the visual centers of the brain. Here, we have used CRISPR-based genetic engineering to generate a Brn3b-mCherry reporter mouse without altering the endogenous expression of Brn3b. In our mouse line, mCherry faithfully recapitulates normal Brn3b expression in the retina, the optic tracts, the midbrain tectum, and the trigeminal ganglia. The high sensitivity of mCherry also revealed novel expression of Brn3b in the neuroectodermal cells of the optic stalk during early stages of eye development. Importantly, the fluorescent intensity of Brn3b-mCherry in our reporter mice allows for noninvasive live imaging of RGCs using Scanning Laser Ophthalmoscopy (SLO), providing a novel tool for longitudinal monitoring of RGCs

Risk of climate-induced damage in historical textiles

Eleven wool and silk historic textiles and two modern artist's canvases were examined to determine their water vapour adsorption, moisture dimensional response and tensile behaviour. All the textiles showed a similar general pattern of moisture response. A rise in ambient relative humidity (RH) from dry conditions produced expansion of a textile until a certain critical RH level after which a contraction occurred to a greater or lesser degree depending on the yarn crimp and the weave geometry. The largest expansion recorded between the dry state and 80% RH was 1.2 and 0.9% for wool and silk textiles, respectively. The largest shrinkage of 0.8% at high RH range was experienced by a modern linen canvas. Two potential damage mechanisms related to the moisture response of the textiles—stress building as a result of shrinkage of the textile restrained in its dimensional response and the fretting fatigue when yarns move with friction one against another—were found insignificant in typical textile display environments unless the textiles are severely degraded or excessively strained in their mounting

Geography and Poetry. Wawrzyniec Korwin’s Take on Ovid

The article offers a survey of the reception of Ovid in the Wawrzyniec Korwin’s astronomical dissertation Cosmographia dans manuductionem in tabulas Ptolemaei (ed. 1496) by applying literary perspectives of such Ovid`s poems as Metamorphoses, Fasti, Epistulae ex Ponto, Amores and Heroides. The title Korwin’s take on Ovid hints at the actual and real potential of his heritage that is both a fixed, poetic base shared by Korwin since his study at the Cracow Academy as well as a body of references constantly being reinterpreted in response to astronomical and geographical challenges of the work of the Polish writer. The reader is given an insight into the processes shaping Korwin’s borrowings from Ovid and the importance of Cosmographia to the Polish Renaissance culture

Spanish Themes in the Astronomical Treatise of Wawrzyniec Korwin (1465–1527)

In the article Robert K. Zawadzki relates how Wawrzyniec Korwin, a little – known Old – Polish writer described the Iberian peninsula in his astronomical treatise Cosmographia dans manuductionem in tabulas Ptolemaei. This author produced a specific picture of Spain that shared affinity with the Roman and Greek writers’ literary manner of writing about this country. The ancient literature had tended to see Spain as a land of prosperity and a district in which gold could be found as a mineral in the rivers. Korwin adopted this view of Spain. A separate section of Spanish threads in his dissertation are the Roman writers from the Iberian peninsula. The Polish author evokes the figure of Seneca and Lucan to quote fragments of the most important works of these writers. Bringing together Korwin’s remarks and ancient texts which he uses, RKZ demonstrates that the Korwin’s description of Spain although seen by some as an anachronism achieved its aim, it persuaded audiences of the magnificence of Spain