Triangular Trimers on the Triangular Lattice: an Exact Solution

A model is presented consisting of triangular trimers on the triangular lattice. In analogy to the dimer problem, these particles cover the lattice completely without overlap. The model has a honeycomb structure of hexagonal cells separated by rigid domain walls. The transfer matrix can be diagonalised by a Bethe Ansatz with two types of particles. This leads two an exact expression for the entropy on a two-dimensional subset of the parameter space.Comment: 4 pages, REVTeX, 5 EPS figure

Stably uniform affinoids are sheafy

We develop some of the foundations of affinoid pre-adic spaces without Noetherian or finiteness hypotheses. We give some explicit examples of non-adic affinoid pre-adic spaces (including a locally perfectoid one). On the positive side, we also show that if every affinoid subspace of an affinoid pre-adic space is uniform, then the structure presheaf is a sheaf; note in particular that we assume no finiteness hypotheses on our rings here. One can use our result to give a new proof that the spectrum of a perfectoid algebra is an adic space.Comment: Version 2 of the manuscript -- the arguments are now presented for general f-adic rings with a topologically nilpotent unit (the original proofs still go through in this generality

Bethe Ansatz solution of triangular trimers on the triangular lattice

Details are presented of a recently announced exact solution of a model consisting of triangular trimers covering the triangular lattice. The solution involves a coordinate Bethe Ansatz with two kinds of particles. It is similar to that of the square-triangle random tiling model, due to M. Widom and P. A. Kalugin. The connection of the trimer model with related solvable models is discussed.Comment: 33 pages, LaTeX2e, 13 EPS figures, PSFra

Made in Amsterdam : a 1771 cittern by Benoit Joseph Boussu

Cittern-family instruments enjoyed popularity in the second half of the 18th century, most notably in the British Isles and France. Many such instruments from these countries have survived in museums and private collections. This ‘guittar’ fashion also took root in the Netherlands, although very few Dutch-made, late 18th-century citterns have survived. The recent rediscovery of an Amsterdam-made cittern by Benoit Joseph Boussu, previously only known about from written sources, adds another example to this small but important group of Dutch-made instruments. In this article, the Boussu cittern is comprehensively described, based on visual observations, endoscopy and CT-scanning, techniques that also enable a detailed analysis of its inner construction. The instrument’s provenance and the biography of its maker are also discussed. These analyses lead to the conclusion that a cittern, of equal quality and appearance to British and French instruments, had already been built in the Netherlands as early as 1771, and included in its design an innovative watch-key tuning mechanism

Mass Spectrometry-Based Proteomics for Studying Microbial Physiology from Isolates to Communities

With the advent of whole genome sequencing, a new era of biology was ushered in allowing for “systems-biology” approaches to characterizing microbial systems. The field of systems biology aims to catalogue and understand all of the biological components, their functions, and all of their interactions in a living system as well as communities of living systems. Systems biology can be considered an attempt to measure all of the components of a living system and then produce a data-driven model of the system. This model can then be used to generate hypotheses about how the system will respond to perturbations, which can be tested experimentally. The first step in the process is the determination of a microbial genome. This process has, to a large extent, been fully developed, with hundreds of microbial genome sequences completed and hundreds more being characterized at a breathtaking pace. The developments of technologies to use this information and to further probe the functional components of microbes at a global level are currently being developed. The field of gene expression analysis at the transcript level is one example; it is now possible to simultaneously measure and compare the expression of thousands of mRNA products in a single experiment. The natural extension of these experiments is to simultaneously measure and compare the expression of all the proteins present in a microbial system. This is the field of proteomics. With the development of electrospray ionization, rapid tandem mass spectrometry and database-searching algorithms, mass spectrometry (MS) has become the leader in the attempts to decipher proteomes. This research effort is very young and many challenges still exist. The goal of the work described here was to build a state-of-the-art robust MS-based proteomics platform for the characterization of microbial proteomes from isolates to communities. The research presented here describes the successes and challenges of this objective. Proteome analyses of the metal-reducing bacteria Shewanella oneidensis and the metabolically versatile bacteria Rhodopseudomonas palustris are given as examples of the power of this technology to elucidate proteins important to different metabolic states at a global level. The analysis of microbial proteomes from isolates is only the first step of the challenge. In nature, microbial species do not act alone but are always found in mixtures with other species where their intricate interactions are critical for survival. These studies conclude with some of the first efforts to develop methodologies to measure proteomes of simple controlled mixtures of microbial species and then present the first attempt at measuring the proteome of a natural microbial community, a biofilm from an acid mine drainage system. This microbial system illustrates life at the extreme of nature where life not only exists but flourishes in very acidic conditions with high metal concentrations and high temperatures. The technologies developed through these studies were applied to the first deep characterization of a microbial community proteome, the deciphering of the expressed proteome of the acid mine drainage biofilm. The research presented here has led to development of a state-of-the-art robust proteome pipeline, which can now be applied to the proteome analysis of any microbial isolate for a sequenced species. The first steps have also been made toward developing methodologies to characterize microbial proteomes in their natural environments. These developments are key to integrating proteome technologies with genome and transcriptome technologies for global characterizations of microbial species at the systems level. This will lead to understanding of microbial physiology from a global view where instead of analyzing one gene or protein at a time, hundreds of genes/proteins will be interrogated in microbial species as the adapt and survive in the environment

Listener evaluations of violins made from composites

For centuries, wood, and more specifically spruce, has been the material of choice for violin top plates. Lately, carbon fiber instruments have entered the market. Some studies show that composite materials have potential advantages for making instruments [Damodaran, Lessard, and Babu, Acoust. Aust. 43, 117-122 (2015)]. However, no studies exist that evaluate violins made of different composite materials as judged by listeners. For this study, six prototype violins, differing only by the material of the top plate, were manufactured in a controlled laboratory setting. The six prototype violins were judged by experienced listeners in two double-blind experiments. In contrast to popular opinion that violins made from carbon have or lack a specific sound quality, the study provides insights in the diverse sounds and timbres violins from fiber-reinforced polymers can create. It allows an investigation of the links between the perception and the variations in material properties of the soundboards. Additionally, as neither players nor listeners are acquainted with these instruments, these results provide an interesting view on what type of qualities of violin-like sounds are preferred by listeners

Made in Amsterdam: a rediscovered cittern from 1771

Cittern family instruments enjoyed popularity in the second half of the eighteenth century, most notably on the British Isles and in France. Many such instruments from these regions have survived in museums and private collections. This 'guittar' fashion also took root in the northern Netherlands, although very few extant Dutch-made, late eighteenth century citterns have remained. The recent rediscovery of a cittern signed 'BOUSSU, a Amsterdam, 1771', previously only known from written sources, adds another (and early!) example to this small but significant group of Dutch-made instruments. This paper presentation starts with a short introduction on the use of cittern type instruments in late eighteenth-century Holland. Then, the rediscovered cittern is comprehensively described and portrayed, based on visual observations, endoscopy and CT-scanning, which allows for a detailed analysis of its construction. Its known provenance is also presented. Furthermore, it is discussed and argued whether the violin maker Benoit Joseph Boussu (1703-1773) - primarily known for the bowed stringed instruments he produced in his Brussels period between c 1750 and c 1761 - was truly the maker of the instrument, or merely the trader who only signed the bought-in instrument before reselling it. These analyses lead to the conclusion that a cittern, of equal quality and appearance as foreign examples, had already been built in the Netherlands as early as 1771, including in its design a - for those days - innovative watch-key tuning mechanism. Geerten Verberkmoes (1968) holds degrees in chemistry (MSc), music (BMus) and musical instrument making (MA), and has worked in the fields of chemistry education and acoustics. Currently, he is a musical instrument maker and teaches instrument making and acoustics at the School of Arts in Ghent, Belgium. In addition, he is working on a PhD (Ghent University / School of Arts, Ghent) concerning the life and instruments of the eighteenth century violin maker Benoit Joseph Boussu. His research appears in publications such as Early Music and The Galpin Society Journal