Hybrid collocation perturbation for PDEs with random domains

In this work we consider the problem of approximating the statistics of a given Quantity of Interest (QoI) that depends on the solution of a linear elliptic PDE defined over a random domain parameterized by $N$ random variables. The random domain is split into large and small variations contributions. The large variations are approximated by applying a sparse grid stochastic collocation method. The small variations are approximated with a stochastic collocation-perturbation method. Convergence rates for the variance of the QoI are derived and compared to those obtained in numerical experiments. Our approach significantly reduces the dimensionality of the stochastic problem. The computational cost of this method increases at most quadratically with respect to the number of dimensions of the small variations. Moreover, for the case that the small and large variations are independent the cost increases linearly

A Structural Approach to the Analysis of Rock Music

This dissertation situates itself in the middle of an ongoing debate about the applicability of Schenkerian analytical techniques to the analysis of pop and rock music. In particular, it investigates ways in which the standard conceptions of voice leading, harmonic function, and counterpoint may be updated to better apply to this new repertoire. A central claim is that voice-leading structure is intimately related to formal structure such that the two domains are mutually informing. Part I of the dissertation focuses on harmonic and melodic theory. Chapter 2, Harmonic Syntax, advocates for a conception of harmonic function based on syntax and form rather than the identity of specific chords. In this conception, chords other than V, such as IV, II, flat-VII, or even some versions of I, can often be said to function syntactically as the dominant. Chapter 3, The Melodic-Harmonic Divorce, explores contrapuntal paradigms in which the domains of melody and harmony seem to be operating independently. This chapter outlines three types of melodic-harmonic divorce: hierarchy divorce, rotation divorce, and syntax divorce. Part II of the dissertation aims to devise voice-leading models for full song forms. Chapter 4 focuses on AABA form, Chapter 5 on verse-prechorus-chorus, and Chapter 6 on verse-chorus forms. These chapters demonstrate that these common forms are associated with general voice-leading structures that act in dialog with the specific voice-leading structures of songs that exhibit these forms. This part of the dissertation is largely analytical, and has the secondary goal of demonstrating a Schenkerian analytical methodology applied to rock music

The Cochlear Tuning Curve

The tuning curve of the cochlea measures how large an input is required to elicit a given output level as a function of the frequency. It is a fundamental object of auditory theory, for it summarizes how to infer what a sound was on the basis of the cochlear output. A simple model is presented showing that only two elements are sufficient for establishing the cochlear tuning curve: a broadly tuned traveling wave, moving unidirectionally from high to low frequencies, and a set of mechanosensors poised at the threshold of an oscillatory (Hopf) instability. These two components suffice to generate the various frequency-response regimes which are needed for a cochlear tuning curve with a high slope

Kf evaluation in GFRP composites by thermography

Since the presence of a notch in a mechanical component causes a reduction in the fatigue strength, it is important to know the kf value for a given notch geometry and material. This parameter is fundamental in the fatigue design of aeronautical components that are mainly made of composites. kf is available in the literature for numerous types of notch but only for traditional materials such as metals. This paper presents a new practice, based on thermographic data, for the determination of the fatigue notch coefficient kf in composite notched specimens. The innovative aspect of this study is therefore to propose the application on composite materials of a new thermographic procedure to determine kf for several notch geometries: circular, U and V soft and severe notches. It was calculated, for each type of notch, as the ratio between the fatigue limits obtained on the cold and hot zone corresponding to the smooth and notched specimen, respectively. Consequently, this research activity provides, for the first time, a little database of kf for two particular typologies of composite materials showing a fast way to collect further values for different laminates and notch geometries

Occurrence of antibiotics in mussels and clams from various FAO areas

Filter feeders, like mussels and clams, are suitable bioindicators of environmental pollution. These shellfish, when destined for human consumption, undergo a depuration step that aims to nullify their pathogenic microorganism load and decrease chemical contamination. Nevertheless, the lack of contamination by drugs may not be guaranteed. Antimicrobials are a class of drugs of particular concern due to the increasing phenomenon of antibiotic resistance. Their use in breeding and aquaculture is a major cause of this. We developed a multiclass method for the HPLC\ue2\u80\u93MS/MS analysis of 29 antimicrobials, validated according to the Commission Decision 2002/657/UE guidelines, and applied it to 50 mussel and 50 clam samples derived from various Food and Agricultural Organisation marine zones. The results obtained, indicate a negligible presence of antibiotics. Just one clam sample showed the presence of oxytetracycline at a concentration slightly higher than the European Union Maximum residue limit set for fish

The Economically Important Nitrogen Pathways of Southwest Florida

The global phenomenon of burgeoning coastal population growth has led to coastal watershed landscape transformation and ecosystem degradation, prompting policy-makers to set limits on freshwater withdrawals and labile nutrient loads. Important components of Florida’s economies lie in the state’s expansive coastal zone; the organisms driving the billion-dollar recreational fishing industry are rooted in coastal habitats, while the agriculture and real-estate industries sprawl throughout numerous coastal watersheds. This study aimed to identify the connections between anthropogenic land use and essential juvenile fish nursery habitats within the coastal zone, which is the first critical step for sustaining the ecology and related economies of the region. The need for this study arises from the fact that these economies are interconnected through nitrogen, and therefore nitrogen management can influence their prosperity or collapse. Juvenile fish nursery habitats are located in waters that receive nitrogen from adjacent landscapes. Runoff delivers nitrogen derived from human nitrogen use and processing within the watersheds to the juvenile fish nursery habitats. Ecosystem managers must understand that although copious amounts of nitrogen applied to land may ultimately support nursery habitat foodwebs, overwhelming nitrogen loads may also create algal blooms that decay and cause lethal hypoxic events leading to ecosystem degradation. This study aims to pinpoint the specific nitrogen sources that support primary production and ultimately fish production in watersheds dominated by agricultural landscapes and residential neighborhoods. Stable isotopes are versatile tools used to identify these connections. The nitrogen and carbon compounds that make up the moieties of an ecosystem inherently carry information on major nitrogen sources, trophic structure as well as the crucial information concerning dominant nitrogen removal and transformative processes that occur within sediments. Specifically in this study, the stable isotopes of carbon and nitrogen of dissolved inorganic nitrogen, primary producers, and fish were used to identify 1) the connections between urban and agricultural landscapes and the nutrients that percolate through the foodweb, 2) the primary producers that support fish biomass, 3) the origins of sedimentary organic matter that can provide new nitrogen via recycling, and 4) the heterogeneous function of fish nursery habitats in polluted systems. This study was conducted during the region’s wet and dry seasons and in over thirty watersheds that differ from each other in terms of size and anthropogenic influence. In agricultural watersheds, nitrogen derived from row crops and tree crops ultimately supported fish production during the wet season. Convective afternoon thunderstorms coupled with runoff delivered nitrogen from the landscape to receiving waters. These nutrients supported phytoplankton which deposited into the sediments and supported benthic foodwebs. During the dry season, nitrogen derived from row crops and nitrogen transformation in the sediments ultimately supported fish production. In this case, irrigation water used for agriculture delivered nitrogen from lands covered with row crops to the nursery habitats in receiving waters. The dry season was characterized by the nitrogen transformation process known as dissimilatory nitrogen reduction to ammonium (DNRA), where biologically available nitrate is converted to biologically available ammonium. Phytoplankton deposits, most likely delivered during the wet season, were recycled through the slow burning DNRA processes, which provided nitrogen for the benthic microalgae that dominated in the dry season. These organisms in turn supported benthic communities which ultimately supported dry season fish production.  In small urban watersheds, nitrogen derived from septic tanks, lawn irrigation, leaky sewage pipes, and atmospheric deposition ultimately supported fish production via phytoplankton, but unlike the nitrogen sources in agricultural watersheds, these sources (with the exception of atmospheric deposition) were seasonally consistent because a mechanisms to deliver nitrogen derived from septic tanks, lawn fertilizer, and leaky sewage pipes were, at least to some extent, available during both seasons. In polluted, tidal, fish-nursery habitats, the specific mechanism that allowed nursery habitats to decrease the ratio of mortality over growth rates of juvenile fish was not consistent among systems. These mechanisms were likely dependent on physical-chemical parameters and stream geomorphology. If the geomorphology or physical-chemical characteristics of nursery habitats are not adequate to set up an efficient nitrogen transfer process to fish, these habitats become more of a haven from predators rather than a source of food for fish.  This study has several implications for management. Managers must first recognize that microalgae are dominant supporters of tidal nursery foodwebs. Managers must define the relationship between nitrogen loads and fish abundance. If this relationship is unknown, the results of increasing nitrogen loads on fish production will remain uncertain; foodwebs in nursery habitats may collapse due to eutrophication, or fish abundance may increase due to increases in food supply. Connectivity factors derived from stable isotope mechanistic mass-balance models can be used as measurable targets for groups of watersheds. The use of wetlands as nitrogen remediation tools may not be effective at removing nitrogen; nitrogen transformation processes such as DNRA likely outweigh removal processes in wetland soils