197 research outputs found
Alter Theocritus? Joachim Camerarius’ griechische Supplemente zu Theokrits Herakliskos und dem sogenannten Herakles leontophonos
Alter Theocritus? Joachim Camerarius’ griechische Supplemente zu Theokrits Herakliskos und dem sogenannten Herakles leontophonos
Since editions of Theocritus from the early sixteenth century, the two poems Heracliscus (“Little Heracles”) and the so‑called Heracles leontophonos (“Heracles the Lionslayer”) have been regarded as incomplete. This diagnosis was confirmed at least for the Heracliscus by the publication of a papyrus in 1930, whereas the Heracles leontophonos is now generally accepted as being complete. This paper presents the Greek supplements made for these poems by the German Hellenist Joachim Camerarius (1500‑1574) in collaboration with his friend and colleague Helius Eobanus Hessus (1488‑1540). The texts are analysed with regard to their sources and relations to the originals. Thus, Camerarius is shown to be a good observer of the texts, who makes extensive use of ancient sources (e.g. Homer, the Aspis and the Megara) for his supplements. An edition with German translation is given in the Appendix, along with Hessus’ Latin rendering of Camerarius’ Greek supplements
Simultaneous phase, amplitude, and polarization control of femtosecond laser pulses
We present a serial pulse shaper design which allows us to shape the phase,
amplitude, and polarization of fs laser pulses independently and
simultaneously. The capabilities of this setup are demonstrated by
implementing a method for generating parametrically tailored laser pulses.
This method is applied on the ionization of NaK molecules by feedback loop
optimization, employing a temporal sub pulse encoding. Moreover, we introduce
and characterize a further development of this common path pulse shaper scheme
for full control of all light field parameters
Photoassociation and coherent transient dynamics in the interaction of ultracold rubidium atoms with shaped femtosecond pulses - I. Experiment
We experimentally investigate various processes present in the
photoassociative interaction of an ultracold atomic sample with shaped
femtosecond laser pulses. We demonstrate the photoassociation of pairs of
rubidium atoms into electronically excited, bound molecular states using
spectrally cut femtosecond laser pulses tuned below the rubidium D1 or D2
asymptote. Time-resolved pump-probe spectra reveal coherent oscillations of the
molecular formation rate, which are due to coherent transient dynamics in the
electronic excitation. The oscillation frequency corresponds to the detun-ing
of the spectral cut position to the asymptotic transition frequency of the
rubidium D1 or D2 lines, respectively. Measurements of the molecular
photoassociation signal as a function of the pulse energy reveal a non-linear
dependence and indicate a non-perturbative excitation process. Chirping the
association laser pulse allowed us to change the phase of the coherent
transients. Furthermore, a signature for molecules in the electronic ground
state is found, which is attributed to molecule formation by femtosecond
photoassociation followed by spontaneous decay. In a subsequent article [A.
Merli et al., submitted] quantum mechanical calculations are presented, which
compare well with the experimental data and reveal further details about the
observed coherent transient dynamics
TGFβ-Signaling and FOXG1-Expression Are a Hallmark of Astrocyte Lineage Diversity in the Murine Ventral and Dorsal Forebrain
Heterogeneous astrocyte populations are defined by diversity in cellular environment, progenitor identity or function. Yet, little is known about the extent of the heterogeneity and how this diversity is acquired during development. To investigate the impact of TGF (transforming growth factor) β-signaling on astrocyte development in the telencephalon we deleted the TGFBR2 (transforming growth factor beta receptor 2) in early neural progenitor cells in mice using a FOXG1 (forkhead box G1)-driven CRE-recombinase. We used quantitative proteomics to characterize TGFBR2-deficient cells derived from the mouse telencephalon and identified differential protein expression of the astrocyte proteins GFAP (glial fibrillary acidic protein) and MFGE8 (milk fat globule-EGF factor 8). Biochemical and histological investigations revealed distinct populations of astrocytes in the dorsal and ventral telencephalon marked by GFAP or MFGE8 protein expression. The two subtypes differed in their response to TGFβ-signaling. Impaired TGFβ-signaling affected numbers of GFAP astrocytes in the ventral telencephalon. In contrast, TGFβ reduced MFGE8-expression in astrocytes deriving from both regions. Additionally, lineage tracing revealed that both GFAP and MFGE8 astrocyte subtypes derived partly from FOXG1-expressing neural precursor cells
Coherent control with shaped femtosecond laser pulses applied to ultracold molecules
We report on coherent control of excitation processes of translationally
ultracold rubidium dimers in a magneto-optical trap by using shaped femtosecond
laser pulses. Evolution strategies are applied in a feedback loop in order to
optimize the photoexcitation of the Rb2 molecules, which subsequently undergo
ionization or fragmentation. A superior performance of the resulting pulses
compared to unshaped pulses of the same pulse energy is obtained by
distributing the energy among specific spectral components. The demonstration
of coherent control to ultracold ensembles opens a path to actively influence
fundamental photo-induced processes in molecular quantum gases
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