The average shape of large waves in the coastal zone

The ability of the NewWave focused wave group (the scaled auto-correlation function) to represent the average shape in time of large waves in a random sea state makes it a useful tool for the design of offshore structures. However, the profile has only been validated against field data for waves on deep and intermediate water depths. A similar validation is advisable when applying NewWave to shallow water problems,where waves are less dispersive and more nonlinear. For this purpose, data recorded by two Channel Coastal Observatory (CCO) wave buoys during two large storms in January 2014 are analysed to assess the ability of NewWave to replicate the average shape of large waves in shallow water. A linear NewWave profile is shown to successfully capture the average shape of the largest waves from the Perranporth and Porthleven wave buoys during these large storm events. The differences between the measurements obtained by a surface-following buoy and a fixed sensor become important when considering the ability of a second-order corrected NewWave profile to capture weakly nonlinear features of the measured data. A general expression for this effect is presented for weakly nonlinear waves on intermediate water depths, leading to Lagrangian second-order sum corrections to the linear NewWave profile. A second-order corrected NewWave profile performs reasonably well in capturing the average features of large waves recorded during the January storms. These findings demonstrate that the NewWave profile is valid in relatively shallow water (kpD values less than 0.5), and so may have potential for use as a design wave in coastal engineering applications

On the flexibility of the design of Multiple Try Metropolis schemes

The Multiple Try Metropolis (MTM) method is a generalization of the classical Metropolis-Hastings algorithm in which the next state of the chain is chosen among a set of samples, according to normalized weights. In the literature, several extensions have been proposed. In this work, we show and remark upon the flexibility of the design of MTM-type methods, fulfilling the detailed balance condition. We discuss several possibilities and show different numerical results

Phase manipulation and the harmonic components of ringing forces on a surface-piercing column

The Stokes-type expansion for the hydrodynamic force on a column in a regular wave can be written to 4th order as φφφφφφ 2coscos4cos3cos2coscos 44233122044433322211 afafafafafafafF ++++++= where the coefficients f represent wave to force transfer functions (including implicit phase shifts) and a is the incoming linear wave amplitude. Note the structure of the terms multiplying coefficients such as f33 where the power of the amplitude term is the same as the frequency harmonic (here both 3), and the terms multiplying terms such as f42 where the power of the amplitude is greater than that of the frequency harmonic by 2. In the notation of Stokes expansions, these correspond to sum and difference components respectively. For ringing we are mostly concerned with the sum harmonics. Whilst these individual harmonic components are easy to extract for regular wave forcing, this is much more difficult for broadbanded waves trains, either random or wave groups, where the simple Stokes terms are replaced by summations of products of linear terms and each net higher harmonic contributes across an increasingly broad range of frequencies. There are then strict limits as to what can be achieved by simple frequency filtering. Here we are concerned with the nonlinear force components generated by isolated compact wave group

Far-infrared to millimeter astrophysical dust emission I: A model based on physical properties of amorphous solids

We propose a new description of astronomical dust emission in the spectral region from the Far-Infrared to millimeter wavelengths. Unlike previous classical models, this description explicitly incorporates the effect of the disordered internal structure of amorphous dust grains. The model is based on results from solid state physics, used to interpret laboratory data. The model takes into account the effect of absorption by Disordered Charge Distribution, as well as the effect of absorption by localized Two Level Systems. We review constraints on the various free parameters of the model from theory and laboratory experimental data. We show that, for realistic values of the free parameters, the shape of the emission spectrum will exhibit very broad structures which shape will change with the temperature of dust grains in a non trivial way. The spectral shape also depends upon the parameters describing the internal structure of the grains. This opens new perspectives as to identifying the nature of astronomical dust from the observed shape of the FIR/mm emission spectrum. A companion paper will provide an explicit comparison of the model with astronomical data.Comment: accepted in A&A, 21 pages, 9 figure

Searching for Exoplanets Using a Microresonator Astrocomb

Detection of weak radial velocity shifts of host stars induced by orbiting planets is an important technique for discovering and characterizing planets beyond our solar system. Optical frequency combs enable calibration of stellar radial velocity shifts at levels required for detection of Earth analogs. A new chip-based device, the Kerr soliton microcomb, has properties ideal for ubiquitous application outside the lab and even in future space-borne instruments. Moreover, microcomb spectra are ideally suited for astronomical spectrograph calibration and eliminate filtering steps required by conventional mode-locked-laser frequency combs. Here, for the calibration of astronomical spectrographs, we demonstrate an atomic/molecular line-referenced, near-infrared soliton microcomb. Efforts to search for the known exoplanet HD 187123b were conducted at the Keck-II telescope as a first in-the-field demonstration of microcombs

New neutron-rich nuclei Zr103,104 and the A100 region of deformation

Partial decay schemes in the neutron-rich nuclei Zr103 and Zr104 have been measured for the first time and rotational bands in Zr100 102 have been extended to spins of up to 10Latin small letter h with stroke by observing prompt rays from the spontaneous fisson of Cm248. These nuclei are among the most deformed known at low spin and excitation energy. The level structures in the odd-A nuclei show that the h11/2 intruder orbital plays an important role in stabilizing the deformation in this region

Advancing research paradigms and pathophysiological pathways in psoriatic arthritis and ankylosing spondylitis: Proceedings of the 2017 Platform for the Exchange of Expertise and Research (PEER) Meeting

The seronegative spondyloarthropathies, including psoriatic arthritis (PsA) and ankylosing spondylitis (AS), are characterized by varied clinical symptoms, severity, and disease course [1], [2]. Diagnosis and monitoring can be challenging because there is no definitive laboratory biomarker for reliably measuring inflammation or other disease processes associated with spondyloarthropathies. Over time, many patients with PsA and AS eventually experience significant disability and impaired quality of life [1], [2]. This may be partially accounted for by delays in diagnosis and subsequent treatment [3], as well as the presence of comorbidities. In recent years, research efforts aimed at identifying risk factors for PsA, including clinical, imaging, genetic, and laboratory assessments, have yielded major advances. The Platform for the Exchange of Expertise and Research (PEER) was formed to facilitate the exchange of research insights, sharing of expertise, and discussion of unmet needs in rheumatology research. The objective of the current report is to provide an overview of the 2017 PEER meeting, which was held on May 19–20, 2017, in London, UK, and highlighted the most up-to-date research findings regarding PsA and AS pathophysiology, early detection, comorbidities, and treatment