Laser Interferometer Space Antenna

Following the selection of The Gravitational Universe by ESA, and the successful flight of LISA Pathfinder, the LISA Consortium now proposes a 4 year mission in response to ESA's call for missions for L3. The observatory will be based on three arms with six active laser links, between three identical spacecraft in a triangular formation separated by 2.5 million km. LISA is an all-sky monitor and will offer a wide view of a dynamic cosmos using Gravitational Waves as new and unique messengers to unveil The Gravitational Universe. It provides the closest ever view of the infant Universe at TeV energy scales, has known sources in the form of verification binaries in the Milky Way, and can probe the entire Universe, from its smallest scales near the horizons of black holes, all the way to cosmological scales. The LISA mission will scan the entire sky as it follows behind the Earth in its orbit, obtaining both polarisations of the Gravitational Waves simultaneously, and will measure source parameters with astrophysically relevant sensitivity in a band from below $10^{-4}\,$Hz to above $10^{-1}\,$Hz.Comment: Submitted to ESA on January 13th in response to the call for missions for the L3 slot in the Cosmic Vision Programm

Editorial

The Magma edition that is now out in the field brings as its opening text the essay "Crítica fora do esquadro": homage to Antonio Candido, signed by professor Edu Teruki Otsuka, originally written on the occasion of the IX Postgraduate Student Research Seminar of the DTLLC, FFLCH/USP, held in May 2018. From an original and consequent angle, the author investigates a little commented line of Candido's criticism: the analyzes dedicated to those works generally considered eccentric for not adhering to literary trends and conventions of their time and which, for this very reason, end up occupying an unusual position in relation to the canon — in other words, literature “out of the box”.A edição de Magma que agora sai a campo traz como texto de abertura o ensaio “Crítica fora do esquadro: homenagem a Antonio Candido”, assinado pelo professor Edu Teruki Otsuka, originalmente redigido por ocasião do IX Seminário de Pesquisa do Alunos de Pós-graduação do DTLLC, da FFLCH/USP, realizado em maio de 2018. De ângulo original e consequente, o autor investiga uma linha pouco comentada da crítica de Candido: as análises dedicadas àquelas obras tidas geralmente como excêntricas por não aderirem às tendências e às convenções literárias de seu tempo e que, por isso mesmo, acabam ocupando uma posição insólita em relação ao cânone — noutras palavras, a literatura “fora do esquadro”.&nbsp

Noncontact three-dimensional evaluation of surface alterations and wear in NiTi endodontic instruments

Abstract The aim of this study was to undertake a qualitative and quantitative assessment of nanoscale alterations and wear on the surfaces of nickel-titanium (NiTi) endodontic instruments, before and after use, through a high-resolution, noncontact, three-dimensional optical profiler, and to verify the accuracy of the evaluation method. Cutting blade surfaces of two different brands of NiTi endodontic instruments, Reciproc R25 (n = 5) and WaveOne Primary (n = 5), were examined and compared before and after two uses in simulated root canals made in clear resin blocks. The analyses were performed on three-dimensional images which were obtained from surface areas measuring 211 × 211 µm, located 3 mm from their tips. The quantitative evaluation of the samples was conducted before and after the first and second usage, by the recordings of three amplitude parameters. The data were subjected to statistical analysis at a 5% level of significance. The results revealed statistically significant increases in the surface wear of both instruments groups after the second use. The presence of irregularities was found on the surface topography of all the instruments, before and after use. Regardless of the evaluation stage, most of the defects were observed in the WaveOne instruments. The three-dimensional technique was suitable and effective for the accurate investigation of the same surfaces of the instruments in different periods of time

Retinal Chromophore Structure and Schiff Base Interactions in Red-Shifted Channelrhodopsin‑1 from <i>Chlamydomonas augustae</i>

Channelrhodopsins (ChRs), which form a distinct branch of the microbial rhodopsin family, control phototaxis in green algae. Because ChRs can be expressed and function in neuronal membranes as light-gated cation channels, they have rapidly become an important optogenetic tool in neurobiology. While channelrhodopsin-2 from the unicellular alga <i>Chlamydomonas reinhardtii</i> (<i>Cr</i>ChR2) is the most commonly used and extensively studied optogenetic ChR, little is known about the properties of the diverse group of other ChRs. In this study, near-infrared confocal resonance Raman spectroscopy along with hydrogen–deuterium exchange and site-directed mutagenesis were used to study the structure of red-shifted ChR1 from <i>Chlamydomonas augustae</i> (<i>Ca</i>ChR1). These measurements reveal that (i) <i>Ca</i>ChR1 has an all-<i>trans</i>-retinal structure similar to those of the light-driven proton pump bacteriorhodopsin (BR) and sensory rhodopsin II but different from that of the mixed retinal composition of <i>Cr</i>ChR2, (ii) lowering the pH from 7 to 2 or substituting neutral residues for Glu169 or Asp299 does not significantly shift the ethylenic stretch frequency more than 1–2 cm^–1 in contrast to BR in which a downshift of 7–9 cm^–1 occurs reflecting neutralization of the Asp85 counterion, and (iii) the <i>Ca</i>ChR1 protonated Schiff base (SB) has stronger hydrogen bonding than BR. A model is proposed to explain these results whereby at pH 7 the predominant counterion to the SB is Asp299 (the homologue to Asp212 in BR) while Glu169 (the homologue to Asp85 in BR) exists in a neutral state. We observe an unusual constancy of the resonance Raman spectra over the broad range from pH 9 to 2 and discuss its implications. These results are in accord with recent visible absorption and current measurements of <i>Ca</i>ChR1 [Sineshchekov, O. A., et al. (2013) Intramolecular proton transfer in channelrhodopsins. <i>Biophys. J. 104</i>, 807–817; Li, H., et al. (2014) Role of a helix B lysine residue in the photoactive site in channelrhodopsins. <i>Biophys. J. 106</i>, 1607–1617]