Glenn Research Center Quantum Communicator Receiver Design and Development

We investigate, design, and develop a prototype real-time synchronous receiver for the second-generation quantum communicator recently developed at the National Aeronautics and Space Administration (NASA) Glenn Research Center. This communication system exploits the temporal coincidences between simultaneously fired low-power laser sources to communicate at power levels several orders of magnitude less than what is currently achievable through classical means, with the ultimate goal of creating ultra-low-power microsize optical communications and sensing devices. The proposed receiver uses a unique adaptation of the early-late gate method for symbol synchronization and a newly identified 31-bit synchronization word for frame synchronization. This receiver, implemented in a field-programmable gate array (FPGA), also provides a number of significant additional features over the existing non-real-time experimental receiver, such as real-time bit error rate (BER) statistics collection and display, and recovery and display of embedded textual information. It also exhibits an indefinite run time and statistics collection. (c) 2009 Society of Photo-Optical Instrumentation Engineers

Glenn Research Center Quantum Communicator Receiver Design and Development

We investigate, design, and develop a prototype real-time synchronous receiver for the second-generation quantum communicator recently developed at the National Aeronautics and Space Administration (NASA) Glenn Research Center. This communication system exploits the temporal coincidences between simultaneously fired low-power laser sources to communicate at power levels several orders of magnitude less than what is currently achievable through classical means, with the ultimate goal of creating ultra-low-power microsize optical communications and sensing devices. The proposed receiver uses a unique adaptation of the early-late gate method for symbol synchronization and a newly identified 31-bit synchronization word for frame synchronization. This receiver, implemented in a field-programmable gate array (FPGA), also provides a number of significant additional features over the existing non-real-time experimental receiver, such as real-time bit error rate (BER) statistics collection and display, and recovery and display of embedded textual information. It also exhibits an indefinite run time and statistics collection. (c) 2009 Society of Photo-Optical Instrumentation Engineers

Bodies, technology, and the edgework of urban exploration

We have determined the structure of the archaeal sodium/proton antiporter NhaP1 at 7 Å resolution by electron crystallography of 2D crystals. NhaP1 is a dimer in the membrane, with 13 membrane-spanning α-helices per protomer, whereas the distantly related bacterial NhaA has 12. Dimer contacts in the two antiporters are very different, but the structure of a six-helix bundle at the tip of the protomer is conserved. The six-helix bundle of NhaA contains two partially unwound α-helices thought to harbour the ion-translocation site, which is thus similar in NhaP1. A model of NhaP1 based on detailed sequence comparison and the NhaA structure was fitted to the 7 Å map. The additional N-terminal helix 1 of NhaP1, which appears to be an uncleaved signal sequence, is located near the dimer interface. Similar sequences are present in many eukaryotic homologues of NhaP1, including NHE1. Although fully folded and able to dimerize, NhaP1 constructs without helix 1 are inactive. Possible reasons are investigated and discussed

YidC and SecYEG form a heterotetrameric protein translocation channel

The heterotrimeric SecYEG complex cooperates with YidC to facilitate membrane protein insertion by an unknown mechanism. Here we show that YidC contacts the interior of the SecY channel resulting in a ligand-activated and voltage-dependent complex with distinct ion channel characteristics. The SecYEG pore diameter decreases from 8 Å to only 5 Å for the YidC-SecYEG pore, indicating a reduction in channel cross-section by YidC intercalation. In the presence of a substrate, YidC relocates to the rim of the pore as indicated by increased pore diameter and loss of YidC crosslinks to the channel interior. Changing the surface charge of the pore by incorporating YidC into the channel wall increases the anion selectivity, and the accompanying change in wall hydrophobicity is liable to alter the partition of helices from the pore into the membrane. This could explain how the exit of transmembrane domains from the SecY channel is facilitated by YidC

The interaction network of the YidC insertase with the SecYEG translocon, SRP and the SRP receptor FtsY

Abstract YidC/Oxa1/Alb3 are essential proteins that operate independently or cooperatively with the Sec machinery during membrane protein insertion in bacteria, archaea and eukaryotic organelles. Although the interaction between the bacterial SecYEG translocon and YidC has been observed in multiple studies, it is still unknown which domains of YidC are in contact with the SecYEG translocon. By in vivo and in vitro site-directed and para-formaldehyde cross-linking we identified the auxiliary transmembrane domain 1 of E. coli YidC as a major contact site for SecY and SecG. Additional SecY contacts were observed for the tightly packed globular domain and the C1 loop of YidC, which reveals that the hydrophilic cavity of YidC faces the lateral gate of SecY. Surprisingly, YidC-SecYEG contacts were only observed when YidC and SecYEG were present at about stoichiometric concentrations, suggesting that the YidC-SecYEG contact in vivo is either very transient or only observed for a very small SecYEG sub-population. This is different for the YidC-SRP and YidC-FtsY interaction, which involves the C1 loop of YidC and is efficiently observed even at sub-stoichiometric concentrations of SRP/FtsY. In summary, our data provide a first detailed view on how YidC interacts with the SecYEG translocon and the SRP-targeting machinery

Impact of DBP on histology and expression of HSP 70 in gill and liver tissue of Cyprinus carpio

WOS: 000360882900007PubMed: 26311152Di-n-butyl phthalate (DBP) widely used plasticizer in the plastic industry, affects regulation of the endocrine system and causes toxicity in animals. In the present study, the aim was to study the toxic effects/damages of DBP exposure using Hsp70 levels and histopathological changes in Carp liver and gill. Hsp70 expression levels were assessed as specific biomarker of in vivo ecotoxicological stress. Carp (Cyprinus carpio) were exposed to sub-lethal concentration of DBP (di-n-butyl phthalate, 1 mg/L) for 4, 24 and 96 h. Gill and liver tissues were evaluated histopathologically and RNA quantifications for Hsp70 expression levels were carried out using a two-step real-time RT-PCR. In liver, a rapid but non-significant increase in mRNA levels in the first 4 h was observed. mRNA levels significantly increased up to 2-3 fold after 24 and 96 h (p < 0.05). However, irregular mRNA level changes were also recorded: Gill specific and time-dependent regulation of Hsp70 expression were 4-5 fold inhibition after 4 and 24 h (p < 0.05), then increased up to 4 fold after 96 h (p < 0.05). Histopathological findings support altered transcription results as: Epithelial lifting, hyperplasia, fusion of secondary lamellae, telangiectasis, passive hyperemia and hydropic degeneration. Significant alterations of Hsp70 levels were likely due to a tissue specific response against chemical stress, cellular damage and lesions due to DBP. Carp was found to be a suitable experimental model for toxicology, and Hsp70 mRNA levels are reliable, specific biomarkers.Gazi University [04/2012-11]; Turkish Scientific and Technological Research Council of Turkey [212T185]The present study was partially supported by the: Gazi University, Research Fund, through project contract no: 04/2012-11 and The Turkish Scientific and Technological Research Council of Turkey, contract no: 212T185. Special thanks to Pinar Arslan, graduate student from Ankara University for her help with the experimentation