A Data-Driven Approach to Violin Making

Of all the characteristics of a violin, those that concern its shape are probably the most important ones, as the violin maker has complete control over them. Contemporary violin making, however, is still based more on tradition than understanding, and a definitive scientific study of the specific relations that exist between shape and vibrational properties is yet to come and sorely missed. In this article, using standard statistical learning tools, we show that the modal frequencies of violin tops can, in fact, be predicted from geometric parameters, and that artificial intelligence can be successfully applied to traditional violin making. We also study how modal frequencies vary with the thicknesses of the plate (a process often referred to as {\em plate tuning}) and discuss the complexity of this dependency. Finally, we propose a predictive tool for plate tuning, which takes into account material and geometric parameters

Using Mechanical Metamaterials in Guitar Top Plates: A Numerical Study

Featured Application The use of mechanical metamaterials in musical instruments could be an excellent way to engineer the wood of the instrument to obtain a particular sound. It has recently been shown that the mechanical properties of thin, rectangular wooden plates can be tuned by carving them with specific patterns of perforations, effectively realising a 2D wooden mechanical metamaterial. Such a material is of great interest for the construction of musical instruments, as it could allow a new degree of creative control for makers. Furthermore, issues with the shrinking supplies of tone-woods could be alleviated as wood samples that don not meet the desired requirements could simply be altered, instead of being discarded. In this work, we study the effect of the use of these metamaterials in the soundboards of classical guitars. By way of simulations, we evaluate their impact on the modal behaviour and on the sound pressure level of the instrument, as well as on its ability to sustain the load exerted by the strings. Our results show that the metamaterials can tune the instrument's response without compromising its structural integrity. We thus conclude that the use of wooden mechanical metamaterials in the soundboards of classical guitars is feasible and, in many ways, beneficial, not the least since it opens the door to using non-traditional woods with bespoke density and stiffness

1984 Fall, Memphis State University schedule of classes

Memphis State University schedule of classes for fall semester 1984.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1363/thumbnail.jp

1985 Spring, Memphis State University schedule of classes

Memphis State University schedule of classes for spring semester 1985.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1367/thumbnail.jp

The Population History of the Caribbean: Perspectives from Ancient and Modern DNA Analysis

abstract: Although the Caribbean has been continuously inhabited for the last 7,000 years, European contact in the last 500 years dramatically reshaped the cultural and genetic makeup of island populations. Several recent studies have explored the genetic diversity of Caribbean Latinos and have characterized Native American variation present within their genomes. However, the difficulty of obtaining ancient DNA from pre-contact populations and the underrepresentation of non-Latino Caribbean islanders in current research have prevented a complete understanding of genetic variation over time and space in the Caribbean basin. This dissertation uses two approaches to characterize the role of migration and admixture in the demographic history of Caribbean islanders. First, autosomal variants were genotyped in a sample of 55 Afro-Caribbeans from five islands in the Lesser Antilles: Grenada, St. Kitts, St. Lucia, Trinidad, and St. Vincent. These data were used to characterize genetic structure, ancestry and signatures of selection in these populations. The results demonstrate a complex pattern of admixture since European contact, including a strong signature of sex-biased mating and inputs from at least five continental populations to the autosomal ancestry of Afro-Caribbean peoples. Second, ancient mitochondrial and nuclear DNA were obtained from 60 skeletal remains, dated between A.D. 500–1300, from three archaeological sites in Puerto Rico: Paso del Indio, Punta Candelero and Tibes. The ancient data were used to reassesses existing models for the peopling of Puerto Rico and the Caribbean and to examine the extent of genetic continuity between ancient and modern populations. Project findings support a largely South American origin for Ceramic Age Caribbean populations and identify some genetic continuity between pre and post contact islanders. The above study was aided by development and testing of extraction methods optimized for recovery of ancient DNA from tropical contexts. Overall, project findings characterize how ancient indigenous groups, European colonial regimes, the African Slave Trade and modern labor movements have shaped the genomic diversity of Caribbean islanders. In addition to its anthropological and historical importance, such knowledge is also essential for informing the identification of medically relevant genetic variation in these populations.Dissertation/ThesisZipped file contains Appendices A-K. Supplemental tables, figures, protocols and spreadsheets associated with dissertation.Doctoral Dissertation Anthropology 201

Advancements and optimization in ancient DNA protocols

The recovery of ancient DNA can only be achieved through the destructive sampling of archaeological remains. It is, therefore, of utmost importance to maximize the efficiency of both the laboratory protocols utilized and the data generated in this fashion. Here we present four manuscripts detailing a set of suggested best-practice sampling and analyses guidelines aimed at making the destructive sampling of ancient remains a more ethical and informed process. Manuscript 1 represents the first large-scale, systematic investigation of DNA preservation in Medieval skeletal remains spanning 23 possible sampling locations. We find DNA preservation to be best in cortical bone recovered from the cochlear region of the petrous pyramid, the vertebral body and superior vertebral arch of thoracic vertebrae, the exterior neck of the tali, the shaft and apical tuft of distal phalanges, as well as material recovered from the interior of the dental pulp chamber, dentin, and cementum of molars. In Manuscript 2 we provide the sampling protocols developed for the generation of bone powder from these sampling locations in both text and video formats. In Manuscript 3 we demonstrate the utility of extended screening of the datasets generated from the next generation sequencing of DNA recovered using these techniques by detailing two new high-coverage Yersinia pestis genomes recovered from these same samples. These genomes, despite not being recovered from a site exhibiting any epidemic context, provide strong evidence that Pestis secunda originated from a central European rodent refugia, continued to evolve, and later re-emerged to re-infect the human population and eventually spread back into eastern Eurasia. Manuscript 4 details a successful proof-of-concept manuscript detailing the feasibility of recovering very long DNA fragments ( > 8 kilobase pairs) from modern human dental calculus for use in the de novo assembly of high-quality oral microbiome reference genomes

Advanced analytical diagnostics applied to human osteological remains

Le ossa antiche, recuperate dai contesti archeologici e preservati all’interno dei Musei, rappresentano una preziosa fonte di informazioni sull'alimentazione, lo stato di salute, la mobilità delle popolazioni antiche nonché sulla demografia e condizioni ambientali del passato, utili a ricercatori e accademici. A seguito dello sviluppo di moderne tecnologie delle scienze omiche, i reperti osteologici sono sempre più richiesti e questo ha comportato un aumento dell'analisi del DNA antico (aDNA). I metodi di campionamento per l'estrazione del DNA antico sono prevalentemente distruttivi e spesso possono compromettere i reperti osteologici per ulteriori future analisi o per studi in altri campi di ricerca. Oltre al campionamento invasivo e distruttivo, in condizioni di scarsa conservazione dell’osso archeologico causata da alterazioni tafonomiche e diagenetiche, il sequenziamento del DNA antico può essere un'operazione estremamente costosa. Dati gli elevati costi della procedura di sequenziamento dell'aDNA, in questo lavoro di ricerca è stato condotto uno studio analitico mediante spettroscopia a raggi infrarossi (FTIR) per sviluppare un metodo di pre-screening affidabile, veloce ed economico per determinare la presenza/assenza di molecole genetiche in un campione osseo archeologico. La spettroscopia IR è uno strumento utile in quanto è rapida, minimamente distruttiva, economica e sensibile alle variazioni delle proprietà strutturali delle componenti organiche (collagene) e inorganiche (nano cristalli di bioapatite) che costituiscono l’osso. A livello ultrastrutturale, le componenti organiche e inorganiche possono stabilire forti legami con il DNA , stabilizzandolo e determinando la sua sopravvivenza nel tempo. Da campioni archeologici (di epoche e provenienze diverse) estremamente alterati a moderne ossa fresche, abbiamo valutato la sensibilità e l'efficacia di nuovi parametri IR per caratterizzare la diagenesi subita dalle ossa tenendo in considerazioni i cambiamenti delle condizioni climatico–ambientali e di seppellimento. Il lavoro è stato esteso per esaminare le modificazioni indotte dalla diagenesi sulla struttura secondaria del collagene conservato, valutandone gli effetti sui cristalli di bioapatite. I risultati ottenuti dimostrano che il parametro IR che descrive l’ordine/disordine atomico, utilizzato in questa ricerca, è vantaggioso per il monitoraggio di variazioni minime nella struttura e nelle proprietà chimiche della bioapatite nonché indirettamente nel collagene. Questo metodo potrebbe migliorare il processo di selezione dei campioni ossei nonché la loro idoneità per analisi specifiche, ad es. analisi genetiche, paleoproteomiche e degli isotopi stabili sulla base delle analisi spettrali. Viene qui proposto inoltre un modello predittivo funzionale con i parametri infrarossi utilizzati, al fine di determinare il parametro più predittivo per la prensenza/assenza di DNA, utile per ridurre i costi delle analisi genetiche. Dai dati ottenuti, la qualità/quantità di aDNA risulterebbe non essere determinabile a causa dell'influenza di fattori ambientali locali.Ancient bone tissues, recovered from archaeological contexts and preserved within the Museums, represent a valuable source of information on health, diet, mobility of ancient populations as well as on demographics and environmental conditions of the past, useful for researchers and academics. Following the development of modern technologies of omic sciences, osteological finds are increasingly requested and this has led to an increase in the analysis of ancient DNA (aDNA). Sampling methods for ancient DNA extraction are predominantly destructive and may often compromise osteological findings for further future analysis or for studies in other research fields. In addition to invasive and destructive sampling, in poor conservation conditions of the archaeological bone caused by taphonomic and diagenetic alterations, the sequencing of ancient DNA can be an extremely expensive operation. Given the high costs of the aDNA sequencing procedure, an analytical study by means of infrared spectroscopy (FTIR) was conducted in this research work to develop a reliable, fast and inexpensive pre-screening method to determine presence/absence of genetic molecules in an archaeological bone sample. Infrared spectroscopy is a useful tool fast, minimally destructive, inexpensive and sensitive to changes in the structural properties of the organic (collagen) and inorganic (bioapatite nanocrystals) components that make up bone. At the ultrastructural level, the organic and inorganic components of bone may stabilize strong bounds with DNA, stabilizing it and determining its survival over time. The sensitivity and efficiency of new IR parameters was tested on fresh bones and extremely altered archaeological samples, characterized by different chronology and origin. The diagenesis undergone by the bones was characterized taking into account changes in climatic-environmental and burial conditions. The research was expanded by examining changes induced by diagenesis on the secondary structure of collagen preserved, evaluating their effects on bioapatite crystals. The results obtained demonstrate that the IR parameter used in this research, that describes the atomic order/disorder, is advantageous for monitoring minimal changes in the structure and chemical properties of bioapatite as well as indirectly in collagen. This method may improve the selection process of bone samples as well as their suitability for specific analyzes, e.g. genetic, paleo-proteomic and stable isotope analysis on the basis of infrared spectra. A functional predictive model with the infrared parameters used, in order to determine the most predictive parameter for the presence/absence of DNA, allowing to reduce the costs of genetic analyzes, was proposed here. The results obtained, shows that the quality/quantity of aDNA cannot be determined due to the influence of local environmental factors

Washington University Record, March 21, 2003

https://digitalcommons.wustl.edu/record/1961/thumbnail.jp