Upregulation of the SERCA-type Ca2+ pump activity in response to endoplasmic reticulum stress in PC12 cells

Background  

Ca²⁺-ATPases of endoplasmic reticulum (SERCAs) are responsible for maintenance of the micro- to millimolar Ca²⁺ ion concentrations within the endoplasmic reticulum (ER) of eukaryotic cells. This intralumenal Ca²⁺ storage is important for the generation of Ca²⁺ signals as well as for the correct folding and posttranslational processing of proteins entering ER after synthesis. ER perturbations such as depletion of Ca²⁺ or abolishing the oxidative potential, inhibition of glycosylation, or block of secretory pathway, activate the Unfolded Protein Response, consisting of an upregulation of a number of ER-resident chaperones/stress proteins in an effort to boost the impaired folding capacity.     

Demonstration of a transportable 1 Hz-linewidth laser

We present the setup and test of a transportable clock laser at 698 nm for a strontium lattice clock. A master-slave diode laser system is stabilized to a rigidly mounted optical reference cavity. The setup was transported by truck over 400 km from Braunschweig to Düsseldorf, where the cavity-stabilized laser was compared to a stationary clock laser for the interrogation of ytterbium (578 nm). Only minor realignments were necessary after the transport. The lasers were compared using a Ti:Sapphire frequency comb as a transfer oscillator. The generated virtual beat showed a combined linewidth below 1 Hz (at 1156 nm). The transport back to Braunschweig did not degrade the laser performance, as was shown by interrogating the strontium clock transition.     

Analytical calculation of in-plane response of plates with concentrated masses to impact and application to pyroshock simulation

In aerospace missions pyroshocks occur due to controlled explosions of ordnance devices enabling the functionality of space modules. These shocks result from deployment mechanisms or opening solar sails and can cause failures of electronic devices and structures. Thus, essential components for assuring the reliability of modules are pyroshock tests for the completion of which strict requirements by the aerospace administrations have to be met. One of them is the definition of a specific acceleration signal and, based on this, the Shock Response Spectrum (SRS) for each part.So far, there is rather empirical than analytical knowledge about producing desired SRS with mechanical impacts and its characteristics due to the variation of input parameters. In this paper a widespread testing procedure for far-field pyroshocks is discussed which is realized by the in-plane impact of a hammer pendulum on a plate including the test specimen. The mechanical model consists of the contact between a rigid sphere and a free deformable rectangular plate with attached masses including subsequent propagation and reflection of longitudinal waves. In order to allow for a prediction of the acceleration field and the corresponding SRS due to the impact the problem is solved semi-analytically by using Hertzian contact theory, the Galerkin-procedure and numerical integration in time domain. The in-plane problem has, to the best of the authors' knowledge, not yet been treated in the literature in the way presented.The results calculated are compared with experimental data showing very good coincidence and allowing for a fast prediction of far-field pyroshock tests due to the impact excitation by a hammer pendulum. Hence, the framework of this paper is an enrichment for the current state of the art considering analytical pyroshock simulation. By better understanding the effect of pyroshocks to one and two dimensional structures a reduction of costs as well as durations for testing procedures seems promising.