Technische Universität Darmstadt

About: Technische Universität Darmstadt is a education organization based out in Darmstadt, Germany. It is known for research contribution in the topics: Computer science & Context (language use). The organization has 17316 authors who have published 40619 publications receiving 937916 citations. The organization is also known as: Darmstadt University of Technology & University of Darmstadt.

Large reversible magnetocaloric effect in Ni-Mn-In-Co

Abstract: We report on the high irreversible adiabatic temperature change of −8 K in a magnetic field change of 1.95 T in the Heusler compound Ni45.7Mn36.6In13.5Co4.2 showing a first-order magnetostructural transition. Due to the large thermal hysteresis of 10 K, this high ΔTad cannot be obtained in a cyclic way but still the reversible magnetocaloric effect amounts to −3 K—an unexpectedly high value which compares to the ΔTad of La(Fe,Si,Co)13. In order to reveal the nature of this high reversible magnetocaloric effect, in-situ temperature dependent optical microscopy of minor loops of thermal hysteresis has been done.

Reconfigurable Folded Reflectarray Antenna Based Upon Liquid Crystal Technology

Abstract: A reconfigurable antenna based on the liquid crystal technology is presented in this paper. The antenna comprises a planar lower reflector with an incorporated feed at its center and a polarizing grid on top as an upper reflector. The lower reflector is utilized to collimate the beam and to twist the polarization. The polarizing grid selects the polarization for the transmission and reflects the orthogonally polarized waves toward the lower reflector. Combining reflector elements with a polarizing grid allows performing additional phase adjustment on the upper reflector for beam steering. Reconfigurability is maintained by the upper reflector, in which a liquid crystal mixture is used as a tunable substrate. The liquid crystal layer is tuned with a bias voltage configuration to obtain an appropriate phase adjustment for the beam steering. As a proof of concept, the beam steering capability of the antenna is demonstrated by steering the main beam to $-6^{\circ}$ , 0 $^{\circ}$ , and 6 $^{\circ}$ at 78 GHz. The measured gain at 78 GHz is 25.1 dB. The proposed antenna configuration is a promising candidate for reconfigurable, high-gain, low-profile, and low-cost antennas.

An ancient Wnt-Dickkopf antagonism in Hydra.

Abstract: The dickkopf (dkk) gene family encodes secreted antagonists of Wnt signalling proteins, which have important functions in the control of cell fate, proliferation, and cell polarity during development. Here, we report the isolation, from a regeneration-specific signal peptide screen, of a novel dickkopf gene from the fresh water cnidarian Hydra. Comparative sequence analysis demonstrates that the Wnt antagonistic subfamily Dkk1/Dkk2/Dkk4 and the non-modulating subfamily Dkk3 separated prior to the divergence of cnidarians and bilaterians. In steady-state Hydra, hydkk1/2/4-expression is inversely related to that of hywnt3a. hydkk1/2/4 is an early injury and regeneration responsive gene, and hydkk1/2/4-expressing gland cells are essential for head regeneration in Hydra, although once the head has regenerated they are excluded from it. Activation of Wnt/beta-Catenin signalling leads to the complete downregulation of hydkk1/2/4 transcripts. When overexpressed in Xenopus, HyDkk1/2/4 has similar Wnt-antagonizing activity to the Xenopus gene Dkk1. Based on the corresponding expression patterns of hydkk1/2/4 and neuronal genes, we suggest that the body column of Hydra is a neurogenic environment suppressing Wnt signalling and facilitating neurogenesis.