Enhanced coupling between massive fermions and zone-boundary phonons probed by infrared resonance Raman in bilayer graphene

Few-layer graphene possesses low-energy carriers which behave as massive fermions, exhibiting intriguing properties in both transport and light scattering experiments. By lowering the excitation energy of resonance Raman spectroscopy down to 1.17 eV we target these massive quasiparticles in the low-energy split bands close to the K point. The low excitation energy suppresses some of the Raman processes which are resonant in the visible, and induces a clearer frequency-separation of the sub-structures of the resonant 2D peak. Studying the different intensities of the sub-structures and comparing experimental measurements with fully ab initio theoretical calculations, in the case of bilayer graphene we unveil an enhanced coupling between the massive fermions and the lattice vibrations at the K point, in analogy to what found for the massless fermions of monolayer graphene, and also suggesting that what governs the enhancement is the vicinity of the electron-hole pair momentum to K rather than how small the electron-hole pair energy is.Comment: 14 pages, 10 figure

Ultrafast structural changes direct the first molecular events of vision

視覚に関わるタンパク質の超高速分子動画 --薄暗いところで光を感じる仕組み--. 京都大学プレスリリース. 2023-03-23.Vision is initiated by the rhodopsin family of light-sensitive G protein-coupled receptors (GPCRs). A photon is absorbed by the 11-cis retinal chromophore of rhodopsin, which isomerizes within 200 femtoseconds to the all-trans conformation, thereby initiating the cellular signal transduction processes that ultimately lead to vision. However, the intramolecular mechanism by which the photoactivated retinal induces the activation events inside rhodopsin remains experimentally unclear. Here we use ultrafast time-resolved crystallography at room temperature to determine how an isomerized twisted all-trans retinal stores the photon energy that is required to initiate the protein conformational changes associated with the formation of the G protein-binding signalling state. The distorted retinal at a 1-ps time delay after photoactivation has pulled away from half of its numerous interactions with its binding pocket, and the excess of the photon energy is released through an anisotropic protein breathing motion in the direction of the extracellular space. Notably, the very early structural motions in the protein side chains of rhodopsin appear in regions that are involved in later stages of the conserved class A GPCR activation mechanism. Our study sheds light on the earliest stages of vision in vertebrates and points to fundamental aspects of the molecular mechanisms of agonist-mediated GPCR activation

The 2001 Superoutburst of WZ Sagittae

We report the results of a worldwide campaign to observe WZ Sagittae during its 2001 superoutburst. After a 23-year slumber at V=15.5, the star rose within 2 days to a peak brightness of 8.2, and showed a main eruption lasting 25 days. The return to quiescence was punctuated by 12 small eruptions, of ~1 mag amplitude and 2 day recurrence time; these "echo outbursts" are of uncertain origin, but somewhat resemble the normal outbursts of dwarf novae. After 52 days, the star began a slow decline to quiescence. Periodic waves in the light curve closely followed the pattern seen in the 1978 superoutburst: a strong orbital signal dominated the first 12 days, followed by a powerful /common superhump/ at 0.05721(5) d, 0.92(8)% longer than P_orb. The latter endured for at least 90 days, although probably mutating into a "late" superhump with a slightly longer mean period [0.05736(5) d]. The superhump appeared to follow familiar rules for such phenomena in dwarf novae, with components given by linear combinations of two basic frequencies: the orbital frequency omega_o and an unseen low frequency Omega, believed to represent the accretion disk's apsidal precession. Long time series reveal an intricate fine structure, with ~20 incommensurate frequencies. Essentially all components occurred at a frequency n(omega_o)-m(Omega), with m=1, ..., n. But during its first week, the common superhump showed primary components at n (omega_o)-Omega, for n=1, 2, 3, 4, 5, 6, 7, 8, 9 (i.e., m=1 consistently); a month later, the dominant power shifted to components with m=n-1. This may arise from a shift in the disk's spiral-arm pattern, likely to be the underlying cause of superhumps. The great majority of frequency components ... . (etc., abstract continues)Comment: PDF, 54 pages, 4 tables, 21 figures, 1 appendix; accepted, in press, to appear July 2002, PASP; more info at http://cba.phys.columbia.edu

Predicting needlestick and sharps injuries in nursing students: Development of the SNNIP scale

© 2020 The Authors. Nursing Open published by John Wiley & Sons Ltd. Aim: To develop an instrument to investigate knowledge and predictive factors of needlestick and sharps injuries (NSIs) in nursing students during clinical placements. Design: Instrument development and cross-sectional study for psychometric testing. Methods: A self-administered instrument including demographic data, injury epidemiology and predictive factors of NSIs was developed between October 2018–January 2019. Content validity was assessed by a panel of experts. The instrument's factor structure and discriminant validity were explored using principal components analysis. The STROBE guidelines were followed. Results: Evidence of content validity was found (S-CVI 0.75; I-CVI 0.50–1.00). A three-factor structure was shown by exploratory factor analysis. Of the 238 participants, 39% had been injured at least once, of which 67.3% in the second year. Higher perceptions of “personal exposure” (4.06, SD 3.78) were reported by third-year students. Higher scores for “perceived benefits” of preventive behaviours (13.6, SD 1.46) were reported by second-year students

T-REX Operating Unit 3

OU3 is one of the six Operating Units of the Progetto Premiale T-REX. It is focused on the development of adaptive optics instrumentation for the European Extremely Large Telescope. The main activities of OU3 are the MAORY adaptive optics module, the MICADO infrared camera, the characterisation and forecast of atmospheric parameters for the E-ELT site and general developments for future adaptive optics systems. <P /

Report ETLAT EDA Project: measurements on drag/towing speed law and dynamical behaviour from video analysis with different types of thin line arrays sensors

The purpose of this document is to provide the experimental results performed at the first water tank of the CNR-INSEAN Marine Institute of Rome. The experimental campaign has been developed in order to evaluate the dynamical behaviour of the tested TLA. Two kind of experimental trials have been performed in parallel: the value of drag force of the TLA at varying towing speed and the reconstruction of TLA dynamical behaviour by a video analysis

Report on ETLAT EDA Project: Test of Dummy Sensors in Water Tank

The goal of the \u27Test of dummy sensors in water tank\u27 report is to get data to validate the fluid-dynamic numerical models on the thin line array dynamic behaviour. All the partners, involved in the project, have to realize the dummy sensors (3 diameters, length > 5 m) and measurement of the speed and pressure fields around the sensors with water speed up to 5 m/s. In the present document the experimental measures of the speed and pressure fields of water flowing around TLA sensors at max 5 m/s are exposed. In the first part, the Test Plan and Interface Specification between dummy sensors and water tank are explained. Instead, the second part reports the measured speed and pressure fields with different types of TLA sensors. Test performed at INSEAN towing tank

Poster 245: Prevalence of Low Back Pain in 7542 School Children Between 13 and 15 Years

Objective: To analyze the prevalence of low back pain (LBP) in adolescent subjects. Design: Screening program with questionnaire interview. Setting: Secondary school in Padova, Italy. Participants: 7542 adolescent subjects (3777 boys, 3765 girls; age range, 13 1215y; average age, 14.8\ub11.1y). Interventions: Not applicable. Main Outcome Measures: Prevalence of LBP and correlated factors. Results: 1180 subjects (15.6%) (429 boys, 751 girls) reported 1 or more episodes of LBP; of these, 324 (27.3%) requested further medical investigation. LBP was more frequent in girls (P<.000) and in subjects with familiarity with this problem (P<.000), with long sedentary periods during the day (P=.003), and who lacked regular sports activities (P<.000). In the subjects who practiced sports, aerobics activities correlated with LBP (P=.000), but no significant correlations were found with volleyball, basketball, soccer, and swimming, or with length of training (number hours per week) (P range, .323 12.063). No significant correlation was found with height, weight, body mass index, smoking, or degree of academic gratification (P range, .323 12.063). Conclusions: LBP is a frequent event in the adolescent population, particularly among girls