Different Mechanisms of Calcitonin, Calcitonin Gene-Related Peptide, and Somatostatin Regulation by Glucocorticoids in a Cell Culture of Human Medullary Thyroid Carcinoma

We have employed the TT cell line, a model for the human medullary thyroid carcinoma cell, lo study the regulation of peptide hormone production by glucocorticoids. Complementary DNA probes were used to measure the calcitonin (CT), CT gene-related peptide (CGRP), and somatostatin (SRIF) mRNA levels. Dose-response experiments in serum-free medium showed that dexamethasone (six-day treatment) lowered somatostatin (to 1% of basal) and CGRP mRNA (to 50% of basal) and stimulated CT mRNA (threefold to thirteenfold) with a half-maximal effective concentration of 10−8 M. Time course studies for cells continuously exposed to 10−6 M dexamethasone showed a rapid (within hours) lowering of SRIF mRNA, whereas the effects on CT and CGRP mRNA required six to eight days. These results demonstrate the presence of two mechanisms, transcriptional (somatostatin) and posttranscriptional (the RNA splice decision to make CT or CGRP mRNA). that can be hormonally regulated

Quantum transport and momentum conserving dephasing

We study numerically the influence of momentum-conserving dephasing on the transport in a disordered chain of scatterers. Loss of phase memory is caused by coupling the transport channels to dephasing reservoirs. In contrast to previously used models, the dephasing reservoirs are linked to the transport channels between the scatterers, and momentum conserving dephasing can be investigated. Our setup provides a model for nanosystems exhibiting conductance quantization at higher temperatures in spite of the presence of phononic interaction. We are able to confirm numerically some theoretical predictions.Comment: 7 pages, 4 figure

Transcriptional Regulation of the Human Calcitonin Gene: A Progress Report

We have applied DNA transfer techniques lo study the transcriptional regulation of the calcitonin (CT) gene in a C-cell line (TT) derived from a human medullary thyroid carcinoma. TT cells were transfected with a fusion gene containing the CT gene promoter and 5\u27 -flanking DNA attached to the promoter-less growth hormone gene (reporter). We quantitated the reporter gene product to monitor transcriptional activation by the CT promoter and deletion mutants of the 5\u27 -flanking DNA. We found that the proximal CT promoter which includes the DNA sequence from +1 to -129 bp upstream from the CT transcription start site did not induce transcription in C-cells or in NIH 3T3 cells. The attachment of additional 5\u27-flanking DNA, extending up to -1460 bp enhanced transcription up to twelvefold in TT cells but had no effect on transcription in 3T3 cells. Deletion of a sequence located at -1290 to -820 bp on the CT 5\u27 -flanking DNA abolished the transcription of the reporter gene. Attachment of the DNA sequence located between -1333 to -731 to the fusion gene, containing the CT promoter (+1 to -129) and the reporter gene, restored transcription of the reporter gene in TT cells. We conclude that an enhancer of CT transcription, which is active in C-cells but not in 3T3 cells, is located between -1290 and -820 of the CT 5\u27-flanking DNA

Real space finite difference method for conductance calculations

We present a general method for calculating coherent electronic transport in quantum wires and tunnel junctions. It is based upon a real space high order finite difference representation of the single particle Hamiltonian and wave functions. Landauer's formula is used to express the conductance as a scattering problem. Dividing space into a scattering region and left and right ideal electrode regions, this problem is solved by wave function matching (WFM) in the boundary zones connecting these regions. The method is tested on a model tunnel junction and applied to sodium atomic wires. In particular, we show that using a high order finite difference approximation of the kinetic energy operator leads to a high accuracy at moderate computational costs.Comment: 13 pages, 10 figure

Микротвердость валиков из бронзы ПГ-19М-01, нанесенных как составляющая мултимодального покрытия методом лазерной наплавки

В статье рассматриваются преимущества лазерной наплавки и возможности использования лазерной наплавки для создания мультимодальных покрытий из разнородных металлических материалов. Приведены результаты исследований микротвердости в поперечном сечении наплавленных валиков из алюминиевой бронзы. Показано влияние скорости лазерной наплавки на микротвердость в наплавленных валиках.The advantages and the capabilities of laser cladding are analyses for used laser cladding for applying multimodal coatings from heterogeneous metal work materials. Results of microhardness investigations in cross section of cladding tracks from Al-bronze are exhibited. The influence of cladding velocity on microhardness are examined

Spatio-temporal coherence in vertically emitting GaAs-based electrically driven polariton lasers

Authors gratefully acknowledge the financial support by the state of Bavaria, the DFG within the projects Schn1376-3.1 as well as KL3124/2-1 and the Wurzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter - ct.qmat. S.H. is grateful for funding received within the EPSRC Hybrid Polaritonics programme grant (EP/M025330/1).We report on the implementation of a GaAs-based, vertically emitting electrically pumped polariton laser operated at cryogenic temperatures. The structure consists of a high quality factor AlGaAs/AlAs microcavity (Q=15 000) with two stacks of four GaAs quantum wells and features a Rabi splitting of 11 meV. Polariton lasing manifests by a clear threshold in the input–output characteristics of our device with a sharp drop in the emission linewidth and a continuous blueshift of 0.7 meV above threshold with increasing injection current. We measure spatial and temporal coherence of our device in the condensed phase by utilizing interference spectroscopy. Our results clearly demonstrate that electrically driven polariton lasers have promise as monolithic polaritonic sources of coherent light.PostprintPeer reviewe

Динамика фрикционных процессов при трении нержавеющей стали аустенитного класса 12Х18Н10Т с ультрамелкозернистой структурой

В работе рассматривается экспериментальное исследование динамики фрикционных процессов при трении объемных ультрамелкозернистых материалов. В качестве модельных образцов использовалась нержавеющая сталь аустенитного класса 12Х18Н10Т с ультрамелкозернистой структурой, сформированной методами ABC прессования и прокатки. В процессе сухого трения скольжения осуществлялась регистрация сигналов виброускорений и акустической эмиссии