Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

Surface enhanced Raman spectra from molecules (bipyridyl ethylene) adsorbed on gold dumbells are observed to become increasingly asymmetric (Fano-like) at higher incident light intensity. The electronic temperature (inferred from the anti-Stokes (AS) electronic Raman signal increases at the same time while no vibrational AS scattering is seen. These observations are analyzed by assuming that the molecule-metal coupling contains an intensity dependent contribution (resulting from light-induced charge transfer transitions as well as renormalization of the molecule metal tunneling barrier). We find that interference between vibrational and electronic inelastic scattering routes is possible in the presence of strong enough electron-vibrational coupling and can in principle lead to the observed Fano-like feature in the Raman scattering profile. However the best fit to the observed results, including the dependence on incident light intensity and the associated thermal response is obtained from a model that disregards this coupling and accounts for the structure of the continuous electronic component of the Raman scattering signal. The temperatures inferred from the Raman signal are argued to be only of qualitative value.Comment: 20 pages, 12 figure

Design of a flight control architecture using a non-convex bundle method

We design a feedback control architecture for longitudinal flight of an aircraft. The multi-level architecture includes the flight control loop to govern the short term dynamics of the aircraft, and the autopilot to control the long term modes. Using H1 performance and robustness criteria, the problem is cast as a non-convex and non-smooth optimization program. We present a non-convex bundle method, prove its convergence, and show that it is apt to solve the longitudinal flight control problem

Dynamics of molecular rotors in bulk superfluid helium

Molecules immersed in liquid helium are excellent probes of superfluidity. Their electronic, vibrational and rotational dynamics provide valuable clues about the superfluid at the nanoscale. Here we report on the experimental study of the laser-induced rotation of helium dimers inside the superfluid $^4\mathrm{He}$ bath at variable temperature. The coherent rotational dynamics of $\mathrm{He}_2^*$ is initiated in a controlled way by ultrashort laser pulses, and tracked by means of time-resolved laser-induced fluorescence. We detect the decay of rotational coherence on the nanosecond timescale and investigate the effects of temperature on the decoherence rate. The observed temperature dependence suggests a non-equilibrium evolution of the quantum bath, accompanied by the emission of the wave of second sound. The method offers new ways of studying superfluidity with molecular nano-probes under variable thermodynamic conditions

A theoretical simulation of the resonant Raman spectroscopy of the H2O⋯Cl2 and H2O⋯Br2 halogen-bonded complexes

The resonant Raman spectra of the H2O⋯Cl2 and H2O⋯Br2 halogen-bonded complexes have been studied in the framework of a 2-dimensional model previously used in the simulation of their UV-visible absorption spectra using time-dependent techniques. In addition to the vibrational progression along the dihalogen mode, a progression is observed along the intermolecular mode and its combination with the intramolecular one. The relative intensity of the inter to intramolecular vibrational progressions is about 15% for H2O⋯Cl2 and 33% for H2O⋯Br2. These results make resonant Raman spectra a potential tool for detecting the presence of halogen bonded complexes in condensed phase media such as clathrates and ice.Fil: Franklin Mergarejo, Ricardo. Université Paris Sud; Francia. Centre National de la Recherche Scientifique; Francia. InSTEC; Cuba. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Rubayo Soneira, Jesús. InSTEC; CubaFil: Halberstadt, Nadine. Université Paris Sud; Francia. Centre National de la Recherche Scientifique; FranciaFil: Janda, Kenneth C.. University of California at Irvine; Estados UnidosFil: Apkarian, V. Ara. University of California at Irvine; Estados Unido

What is the numerical nature of pain relief?

Pain relief, or a decrease in self-reported pain intensity, is frequently the primary outcome of pain 10 clinical trials. Investigators commonly report pain relief in one of two ways: using raw units (additive) 11 or using percentage units (multiplicative). However, additive and multiplicative scales have different 12 assumptions and are incompatible with one-another. In this work, we describe the assumptions and 13 corollaries of additive and multiplicative models of pain relief to illuminate the issue from statistical 14 and clinical perspectives. First, we explain the math underlying each model and illustrate these points 15 using simulations, for which readers are assumed to have an understanding of linear regression. Next, we 16 connect this math to clinical interpretations, stressing the importance of statistical models that accurately 17 represent the underlying data; for example, how using percent pain relief can mislead clinicians if the data are actually additive. These theoretical discussions are supported by empirical data from four 19 longitudinal studies of patients with subacute and chronic pain. Finally, we discuss self-reported pain 20 intensity as a measurement construct, including its philosophical limitations and how clinical pain differs 21 from acute pain measured during psychophysics experiments. This work has broad implications for 22 clinical pain research, ranging from statistical modeling of trial data to the use of minimal clinically important differences and patient-clinician communication

Thalamically projecting cells of the lateral cervical nucleus in monkey

The number, location, and morphology of thalamically projecting lateral cervical nucleus (LCN) cells were determined in monkey using retrograde transport of wheatgerm agglutinin-conjugated horseradish peroxidase. These data were compared to the total population of LCN neurons as determined by Nissl stain. In 4 Macaca fascicularis and one Saimiri sciureus the average size of the thalamic projection from LCN was found to be 506 _+ 94 cells contralateral to the injections. Thalamically projecting LCN neurons were located between the lower medulla and the third cervical segment; approximately 90% of these cells were in the first two cervical segments. Morphologic analysis of thalamically projecting LCN cells showed that they were smaller in size, and more oblong in shape in caudal regions of the nucleus. In 3 macaques, the average total number of LCN cells was determined to be 1617 + 908 on one side, in Nissl material. In these Nissl-stained preparations LCN neurons were found as far caudal as the fourth cervical segment; 68% were located in the first two cervical segments. Hence, thalamically projecting LCN neurons in the monkey are located in the rostral portion of the nucleus and comprise about one-third of the total population. Comparison of these data with reports in the literature imply that, unlike the cat, the major projection from LCN in monkeys is to the mesencephalon rather than to the thalamus

Reorganization of functional brain network architecture in chronic osteoarthritis pain

Osteoarthritis (OA) manifests with chronic pain, motor impairment, and proprioceptive changes. However, the role of the brain in the disease is largely unknown. Here, we studied brain networks using the mathematical properties of graphs in a large sample of knee and hip OA (KOA, n = 91; HOA, n = 23) patients. We used a robust validation strategy by subdividing the KOA data into discovery and testing groups and tested the generalizability of our findings in HOA. Despite brain global topological properties being conserved in OA, we show there is a network wide pattern of reorganization that can be captured at the subject-level by a single measure, the hub disruption index. We localized reorganization patterns and uncovered a shift in the hierarchy of network hubs in OA: primary sensory and motor regions and parahippocampal gyrus behave as hubs and insular cortex loses its central placement. At an intermediate level of network structure, frontoparietal and cingulo-opercular modules showed preferential reorganization. We examined the association between network properties and clinical correlates: global disruption indices and isolated degree properties did not reflect clinical parameters; however, by modeling whole brain nodal degree properties, we identified a distributed set of regions that reliably predicted pain intensity in KOA and generalized to hip OA. Together, our findings reveal that while conserving global topological properties, brain network architecture reorganizes in OA, at both global and local scale. Network connectivity related to OA pain intensity is dissociated from the major hub disruptions, challenging the extent of dependence of OA pain on nociceptive signaling.CCDRN, Grant/Award Number: Norte‐08‐5369‐FSE‐000026; Unilabs Boavista and the Grünenthal Young Pain Researcher 2017 Grant; Luso‐American Development Foundation R&D@PhD Scholarship Grant; OARSI Collaborative Scholarship 201