Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Purdue University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 3031 - 3060 of 8613

Full-Text Articles in Entire DC Network

Optimizing The Neural Response To Electrical Stimulation And Exploring New Applications Of Neurostimulation, Kurt Yuqin Qing Apr 2015

Optimizing The Neural Response To Electrical Stimulation And Exploring New Applications Of Neurostimulation, Kurt Yuqin Qing

Open Access Dissertations

Electrical stimulation has been successful in treating patients who suffer from neurologic and neuropsychiatric disorders that are resistant to standard treatments. For deep brain stimulation (DBS), its official approved use has been limited to mainly motor disorders, such as Parkinson's disease and essential tremor. Alcohol use disorder, and addictive disorders in general, is a prevalent condition that is difficult to treat long-term. To determine whether DBS can reduce alcohol drinking in animals, voluntary alcohol consumption of alcohol-preferring rats before, during, and after stimulation of the nucleus accumbens shell were compared. Intake levels in the low stimulus intensity group (n=3, 100&mgr;A …

Go to article

Ergodic Properties Of Countable Extensions, Samuel Joshua Roth Apr 2015

Ergodic Properties Of Countable Extensions, Samuel Joshua Roth

Open Access Dissertations

First, we study countably piecewise continuous, piecewise monotone interval maps. We establish a necessary and sufficient criterion for the existence of a non-decreasing semiconjugacy to an interval map of constant slope in terms of the existence of an eigenvector of an operator acting on a space of measures. Then we give examples, both Markov and non-Markov, for which the criterion is violated. ^ Next, we establish a criterion for the existence of a constant slope map on the extended real line conjugate to a given countably piecewise monotone interval map. We require the given interval map to be continuous, Markov, …

Go to article

Automated Segmentation, Detection And Fitting Of Piping Elements From Terrestrial Lidar Data, Yun-Ting Su Apr 2015

Automated Segmentation, Detection And Fitting Of Piping Elements From Terrestrial Lidar Data, Yun-Ting Su

Open Access Dissertations

Since the invention of light detection and ranging (LIDAR) in the early 1960s, it has been adopted for use in numerous applications, from topographical mapping with airborne LIDAR platforms to surveying of urban sites with terrestrial LIDAR systems. Static terrestrial LIDAR has become an especially effective tool for surveying, in some cases replacing traditional techniques such as electronic total stations and GPS methods. Current state-of-the-art LIDAR scanners have very fine spatial resolution, generating precise 3D point cloud data with millimeter accuracy. Therefore, LIDAR data can provide 3D details of a scene with an unprecedented level of details. However, automated exploitation …

Go to article

Stability Of Machine Learning Algorithms, Wei Sun Apr 2015

Stability Of Machine Learning Algorithms, Wei Sun

Open Access Dissertations

In the literature, the predictive accuracy is often the primary criterion for evaluating a learning algorithm. In this thesis, I will introduce novel concepts of stability into the machine learning community. A learning algorithm is said to be stable if it produces consistent predictions with respect to small perturbation of training samples. Stability is an important aspect of a learning procedure because unstable predictions can potentially reduce users' trust in the system and also harm the reproducibility of scientific conclusions. As a prototypical example, stability of the classification procedure will be discussed extensively. In particular, I will present two new …

Go to article

Understanding How Adults Approach Technological Challenges: A Sequential Mixed Methods Research, Mariana Tafur Arciniegas Apr 2015

Understanding How Adults Approach Technological Challenges: A Sequential Mixed Methods Research, Mariana Tafur Arciniegas

Open Access Dissertations

People from all backgrounds engage with technology in their everyday lives. There is, however, a gap in the public's understanding of technology and limited research on how engineers and non-engineers approach technological challenges. Prior studies have focused on the public's understanding of technology but limited research has been conducted on how people deal with technological challenges as part of their everyday lives. Studying how individuals with non-STEM backgrounds engage with technology will contribute a more comprehensive understanding of strategies for closing the technological literacy gap. Taking into account that technology developments rapidly occur, lifelong learning skills are another critical dimension …

Go to article

Mass Spectrometric Characterization Of Peptide Radical Ions And Implication For Radical Chemistry, Lei Tan Apr 2015

Mass Spectrometric Characterization Of Peptide Radical Ions And Implication For Radical Chemistry, Lei Tan

Open Access Dissertations

Gas-phase radical ion chemistry has attracted increasing research interest from the mass spectrometry (MS) society because it provides new capabilities in bio-analysis which often complements traditional MS methods developed from even-electron ions. Fundamental studies of biomolecule related radical species are essential to broadening the scope of radical chemistry and pushing the frontiers of its analytical applications. This dissertation mainly discusses the gas-phase chemistry of peptide sulfinyl radicals (-SO·), which has been rarely studied before. In order to establish an effective research approach, a method that can generate site-specific peptide sulfinyl radical ion has been developed. This method is based on …

Go to article

Canvas Politics: Norman Lewis And The Art Of Abstract Resistance, Mindy H.M Tan Apr 2015

Canvas Politics: Norman Lewis And The Art Of Abstract Resistance, Mindy H.M Tan

Open Access Dissertations

Norman Lewis (1909-1979) is best remembered, perhaps erroneously, as the first African American Abstract Expressionist. In this dissertation, I argue that he is better suited as a Social Abstractionist and an Abstract Allusionist based on the life he lived, the work he produced, and his involvement in both black art and the Abstract Expressionist movement. ^ I begin by presenting a comprehensive overview of Lewis' biography and oeuvre. Painting from the 1930s to the late 1970s, his aesthetic sensibilities can be categorized into three distinct phases: 1) in the 1930s, answering to the call for a new presentation of the …

Go to article

Well-Posedness And Convergence Of Cfd Two-Fluid Model For Bubbly Flows, Avinash Vaidheeswaran Apr 2015

Well-Posedness And Convergence Of Cfd Two-Fluid Model For Bubbly Flows, Avinash Vaidheeswaran

Open Access Dissertations

The current research is focused on developing a well-posed multidimensional CFD two-fluid model (TFM) for bubbly flows. Two-phase flows exhibit a wide range of local flow instabilities such as Kelvin-Helmholtz, Rayleigh-Taylor, plume and jet instabilities. They arise due to the density difference and/or the relative velocity between the two phases. A physically correct TFM is essential to model these instabilities. However, this is not the case with the TFMs in numerical codes, which can be shown to have complex eigenvalues due to incompleteness and hence are ill-posed as initial value problems. A common approach to regularize an incomplete TFM is …

Go to article

Heat Trace And Heat Content Asymptotics For Schrodinger Operators Of Stable Processes/Fractional Laplacians, Luis Guillermo Acuna Valverde Apr 2015

Heat Trace And Heat Content Asymptotics For Schrodinger Operators Of Stable Processes/Fractional Laplacians, Luis Guillermo Acuna Valverde

Open Access Dissertations

Let V be a bounded and integrable potential over Rd and 0 < α ≤ 2. We show the existence of an asymptotic expansion by means of Fourier Transform techniques and probabilistic methods for the following quantities [special characters omitted] and [special characters omitted] as t ↓ 0. These quantities are called the heat trace and heat content in Rd with respect to V, respectively. Here, p((α)/ t)(x, y) and p( HV/t)(x, y) denote, respectively, the heat kernels of the heat semigroups with infinitesimal generators given by (-Δ)(α/2) and HV = (-Δ)(α/2) + V. The former operator is known as the fractional Laplacian whereas the latter one is known as the fractional Schrödinger Operator. ^ The study …

Go to article

Improving Capacity-Performance Tradeoffs In The Storage Tier, Eric P. Villasenor Apr 2015

Improving Capacity-Performance Tradeoffs In The Storage Tier, Eric P. Villasenor

Open Access Dissertations

Data-set sizes are growing. New techniques are emerging to organize and analyze these data-sets. There is a key access pattern emerging with these new techniques, large sequential file accesses. The trend toward bigger files exists to help amortize the cost of data accesses from the storage layer, as many workloads are recognized to be I/O bound. The storage layer is widely recognized as the slowest layer in the system. This work focuses on the tradeoff one can make with that storage capacity to improve system performance. ^ Capacity can be leveraged for improved availability or improved performance. This tradeoff is …

Go to article

Learning Compact Hashing Codes With Complex Objectives From Multiple Sources For Large Scale Similarity Search, Qifan Wang Apr 2015

Learning Compact Hashing Codes With Complex Objectives From Multiple Sources For Large Scale Similarity Search, Qifan Wang

Open Access Dissertations

Similarity search is a key problem in many real world applications including image and text retrieval, content reuse detection and collaborative filtering. The purpose of similarity search is to identify similar data examples given a query example. Due to the explosive growth of the Internet, a huge amount of data such as texts, images and videos has been generated, which indicates that efficient large scale similarity search becomes more important.^ Hashing methods have become popular for large scale similarity search due to their computational and memory efficiency. These hashing methods design compact binary codes to represent data examples so that …

Go to article

Assessment Of High-Fidelity Collision Models In The Direct Simulation Monte Carlo Method, Andrew Brian Weaver Apr 2015

Assessment Of High-Fidelity Collision Models In The Direct Simulation Monte Carlo Method, Andrew Brian Weaver

Open Access Dissertations

Advances in computer technology over the decades has allowed for more complex physics to be modeled in the DSMC method. Beginning with the first paper on DSMC in 1963, 30,000 collision events per hour were simulated using a simple hard sphere model. Today, more than 10 billion collision events can be simulated per hour for the same problem. Many new and more physically realistic collision models such as the Lennard-Jones potential and the forced harmonic oscillator model have been introduced into DSMC. However, the fact that computer resources are more readily available and higher-fidelity models have been developed does not …

Go to article

The Role Of Entomology In Environmental And Science Education: Comparing Outreach Methods For Their Impact On Student And Teacher Content Knowledge And Motivation, Faith J. Weeks Apr 2015

The Role Of Entomology In Environmental And Science Education: Comparing Outreach Methods For Their Impact On Student And Teacher Content Knowledge And Motivation, Faith J. Weeks

Open Access Dissertations

Outreach programming can be an important way for local students and teachers to be exposed to new fields while enhancing classroom learning. University-based outreach programs are offered throughout the country, including most entomology departments as few individuals learn about insects in school and these programs can be excellent sources of entomological education, as well as models to teach environmental and science education. Each department utilizes different instructional delivery methods for teaching about insects, which may impact the way in which students and teachers understand the insect concepts presented. To determine the impact of using entomology to enhance science and environmental …

Go to article

Growth Of Low Disorder Gaas/Algaas Heterostructures By Molecular Beam Epitaxy For The Study Of Correlated Electron Phases In Two Dimensions, John D. Watson Apr 2015

Growth Of Low Disorder Gaas/Algaas Heterostructures By Molecular Beam Epitaxy For The Study Of Correlated Electron Phases In Two Dimensions, John D. Watson

Open Access Dissertations

The unparalleled quality of GaAs/AlGaAs heterostructures grown by molecular beam epitaxy has enabled a wide range of experiments probing interaction effects in two-dimensional electron and hole gases. This dissertation presents work aimed at further understanding the key material-related issues currently limiting the quality of these 2D systems, particularly in relation to the fractional quantum Hall effect in the 2nd Landau level and spin-based implementations of quantum computation.^ The manuscript begins with a theoretical introduction to the quantum Hall effect which outlines the experimental conditions necessary to study the physics of interest and motivates the use of the semiconductor growth …

Go to article

Orderability And Rigidity In Contact Geometry, Peter Weigel Apr 2015

Orderability And Rigidity In Contact Geometry, Peter Weigel

Open Access Dissertations

We study the existence of positive loops of contactomorphisms on a Liouville-fillable contact manifold (&Sgr;, ξ = ker(α)). Previous results (see [1]) show that a large class of Liouville-fillable contact manifolds admit contractible positive loops. In contrast, we show that for any Liouville-fillable (&Sgr;, α) with dim(&Sgr;) ≥ 7, there exists a Liouville-fillable contact structure ξ' on &Sgr; which admits no positive loop at all. Further, ξ' can be chosen to agree with ξ' on the complement of a Darboux ball. We then define a relative version of orderability for a Legendrian submanifold, and discuss the relationship between the two …

Go to article

Homogeneous And Heterogeneous Rhenium Catalysts For Sustainable Transformations Of Polyols, Alcohols, And Amines, Jing Yi Apr 2015

Homogeneous And Heterogeneous Rhenium Catalysts For Sustainable Transformations Of Polyols, Alcohols, And Amines, Jing Yi

Open Access Dissertations

Biomass-derived molecules, such as sugar polyols and lignin, are promising feedstock for making small and useful organics (SUO) and high value-added organics (HVO). However, the high oxygen to carbon ratio (C:O ≈ 1) prohibits the direct use of biomass-derived molecules as energy carriers and chemicals. Deoxygenation of polyols has become an important challenge in the utilization of biomass resources. Oxorhenium complexes show excellent oxophilicity to transfer oxygen and deoxygenate alcohols. Oxorhenium(VII) complexes can efficiently catalyze the transformation of glycerol to allyl alcohol, acrolein, and propanal. The volatile SUO products were easily separated from the nonvolatile residues via simple distillation. Based …

Go to article

Permutohedra, Configuration Spaces And Spineless Cacti, Yongheng Zhang Apr 2015

Permutohedra, Configuration Spaces And Spineless Cacti, Yongheng Zhang

Open Access Dissertations

It has been known that the configuration space F(R2, n) of n distinct ordered points in R2 deformation retracts to a regular CW complex with n!permutohedra Pn as the top dimensional cells. In this paper, we show that there exists a similar but different permutohedral structure of the spaceCact(n) of spineless cacti with n lobes. Based on these structures, direct homotopy equivalences between F (R2, n) and Cact(n) are then given. It is well known that the little 2-discs space D2(n) is homotopy equivalent toF(R2, n). …

Go to article

Effect Of Maleic Acid On The Selectivity Of Glucose And Fructose Dehydration And Degradation, Ximing Zhang Apr 2015

Effect Of Maleic Acid On The Selectivity Of Glucose And Fructose Dehydration And Degradation, Ximing Zhang

Open Access Dissertations

5-Hydroxymethyfurfural (HMF), a platform chemical can upgrade to a variety of fuels and polymers, can be manufactured from lignocellulose. This study focuses on the Lewis and Brønsted acid effect on hexose dehydration for HMF production. We report the positive effect of maleic acid, a dicarboxylic acid used as Brønsted acid, on the selectivity of hexose dehydration to 5-hydroxymethyfurfural (HMF), and subsequent hydrolysis to levulinic and formic acids. We also describe the kinetic analysis of a Lewis acid (AlCl 3) alone and in combination with HCl or maleic acid to catalyze the isomerization of glucose to fructose, dehydration of fructose …

Go to article

Elastic Waves Along A Fracture Intersection, Bradley C. Abell Apr 2015

Elastic Waves Along A Fracture Intersection, Bradley C. Abell

Open Access Dissertations

Fractures and fracture networks play a significant role in the subsurface hydraulic connectivity within the Earth. While a significant amount of research has been performed on the seismic response of single fractures and sets of fractures, few studies have examined the effect of fracture intersections on elastic wave propagation. Intersections play a key role in the connectivity of a fracture network that ultimately affects the hydraulic integrity of a rock mass. In this dissertation two new types of coupled waves are examined that propagate along intersections. 1) A coupled wedge wave that propagates along a surface fracture with particle motion …

Go to article

Investigating Synergy: Mathematical Models For The Coupled Dynamics Of Hiv And Hsv-2 And Other Endemic Diseases, Christina M Alvey Apr 2015

Investigating Synergy: Mathematical Models For The Coupled Dynamics Of Hiv And Hsv-2 And Other Endemic Diseases, Christina M Alvey

Open Access Dissertations

This dissertation presents epidemiological models that investigate synergy: synergy between HIV and HSV-2 or between humans and mosquitoes in a malaria study. Each of the three coupled disease models addresses different epidemiological questions with regard to gender or disease structure in the context of sexually-transmitted diseases (STDs), while the malaria model focuses on age-structure of the human population. ^ Mounting evidence indicates that HSV-2 infection may increase susceptibility to HIV infection and that co-infection may increase infectiousness. Accordingly, antiviral treatment of people with HSV-2 may mitigate the incidence of HIV in populations where both pathogens occur. To better understand the …

Go to article

Modular Approach To Spintronics, Kerem Yunus Camsari Apr 2015

Modular Approach To Spintronics, Kerem Yunus Camsari

Open Access Dissertations

There has been enormous progress in the last two decades, effectively combining spintronics and magnetics into a powerful force that is shaping the field of memory devices. New materials and phenomena continue to be discovered at an impressive rate, providing an ever-increasing set of building blocks that could be exploited in designing transistor-like functional devices of the future. The objective of this thesis is to provide a quantitative foundation for this building block approach, so that new discoveries can be integrated into functional device concepts, quickly analyzed and critically evaluated. Through careful benchmarking against available theory and experiments we establish …

Go to article

Circular Bessel Field Statistics And The Pursuit Of Far-Subwavelength Resolution, Yulu Chen Apr 2015

Circular Bessel Field Statistics And The Pursuit Of Far-Subwavelength Resolution, Yulu Chen

Open Access Dissertations

The statistical description of wave propagation in random media is important for many applications. While polarized light in systems with weakly interacting scatterers and sufficient overall scatter has zero-mean circular Gaussian statistics, the underlying assumptions break down in the Anderson localization and weakly scattering regimes. Although probability density functions for wave intensity and amplitude exist beyond Gaussian statistics, suitable statistical descriptions for the field with strong and weak random scatter were unknown. The first analytical probability density function for the field that is effective in both the Anderson localization regime and the weakly scattering regime is derived by modeling the …

Go to article

Biology And Ecology Of Bigheaded Carp In An Invaded Ecosystem, Alison Adele Coulter Apr 2015

Biology And Ecology Of Bigheaded Carp In An Invaded Ecosystem, Alison Adele Coulter

Open Access Dissertations

Globally, the homogenization of species has become a threat to biodiversity. As species are transported around the world, a portion of these species, released intentionally or accidentally, may become invasive and can produce negative impacts. Great effort has been invested into early identification and prevention of invasions as these are considered less expensive than managing an invasion. Unfortunately, species may exhibit varying characteristics across ecosystems, and so their behavior and potential survival in a new environment may be difficult to predict. Therefore, I examined trends in the biology and behavior of invasive fishes, including the plasticity surrounding these and how …

Go to article

Studies Of Arctic Halogen Chemistry From The Snowpack To The Gas Phase, Kyle D Custard Apr 2015

Studies Of Arctic Halogen Chemistry From The Snowpack To The Gas Phase, Kyle D Custard

Open Access Dissertations

The temporary depletion of both tropospheric ozone and gaseous mercury during the Arctic springtime has been a focus of active research over the past several decades. Both of these phenomena have been linked to chemical reactions with halogen radicals. In particular, bromine atoms have been shown to act as the primary driver for these chemical depletions, although both chlorine and iodine atoms also contribute. Molecular bromine, along with its oxidation products, have been well studied in the Arctic, yet chlorine has not. Chlorine is known to impact the local oxidation capacity via its high reactivity with volatile organic compounds. Despite …

Go to article

Consequences Of Short-Term Water Temperature Variability To Fish: Current And Future Climate Change Impacts, David P. Coulter Apr 2015

Consequences Of Short-Term Water Temperature Variability To Fish: Current And Future Climate Change Impacts, David P. Coulter

Open Access Dissertations

Water temperature has a profound influence on aquatic ectotherms by affecting all aspects of biological organization; from chemical and molecular functioning to whole-organism and population-level impacts. Natural processes and anthropogenic activities can create conditions where temperatures vary greatly through space and time. While exposure to temperature changes lasting ≥ 24 hours have been examined in some species, it is unclear how more rapid (< 24 hours; sub-daily) thermal fluctuations affect aquatic ectotherms. I used a combination of field observations, laboratory experiments, and modeling simulations to understand: 1) how habitat quality of aquatic ectotherms is affected in thermally dynamic environments; 2) the role of sub-daily temperature fluctuations on growth, survival, and stress responses in juvenile and adult fish; 3) how fish early life stages are affected by sub-daily temperature fluctuations; and 4) what impact thermally dynamic environments have on a model species at a population-level. A model quantifying habitat quality around power plant thermal discharges indicated that elevated and variable discharge temperatures affected habitat quality over a relatively small spatial area for aquatic ectotherms. Models examining elevated temperatures representing climate warming showed that the effects of industrial discharges and climate warming could have an interactive effect on habitat quality by increasing the spatial area and duration over which industrial thermal effluents impact aquatic ectotherms. Laboratory experiments indicated that closely related fishes can respond differently to the same sub-daily temperature fluctuations. Yellow perch (Perca flavescens) had higher consumption and growth under sub-daily temperature fluctuations but developed skin lesions; an indication of thermal stress. In contrast, these same fluctuations reduced growth in physiologically similar walleye (Sander vitreus) …

Go to article

Difficulty As A Concept Inventory Design Consideration: An Exploratory Study Of The Concept Assessment Tool For Statics (Cats), Dana L. Denick Apr 2015

Difficulty As A Concept Inventory Design Consideration: An Exploratory Study Of The Concept Assessment Tool For Statics (Cats), Dana L. Denick

Open Access Dissertations

The ability for engineering students to apply mathematic, scientific and engineering knowledge to real-life problems depends greatly on developing deep conceptual knowledge that structures and relates the meaning of underlying principles. Concept inventories have emerged as a class of tests typically developed for use in higher education science and engineering courses. Concept Inventories (CIs) are multiple-choice tests that are designed to assess students' conceptual understanding within a specific content domain. For example, the CI explored within this study, the Concept Assessment Tool for Statics (CATS) is intended to measure students' understanding of the concepts underlying the domain of engineering statics. …

Go to article

Visibility Computation Through Image Generalization, Jian Cui Apr 2015

Visibility Computation Through Image Generalization, Jian Cui

Open Access Dissertations

This dissertation introduces the image generalization paradigm for computing visibility. The paradigm is based on the observation that an image is a powerful tool for computing visibility. An image can be rendered efficiently with the support of graphics hardware and each of the millions of pixels in the image reports a visible geometric primitive. However, the visibility solution computed by a conventional image is far from complete. A conventional image has a uniform sampling rate which can miss visible geometric primitives with a small screen footprint. A conventional image can only find geometric primitives to which there is direct line …

Go to article

Novel Methods For Manipulating Ion Types In The Solution And Gas Phases For The Structural Analysis Of Biomolecules Using Mass Spectrometry, Christine M Fisher Apr 2015

Novel Methods For Manipulating Ion Types In The Solution And Gas Phases For The Structural Analysis Of Biomolecules Using Mass Spectrometry, Christine M Fisher

Open Access Dissertations

Mass Spectrometry has become a valuable tool for the analysis of a variety of molecules, making it applicable to many fields. The advent of nanoelectrospray ionization (nESI) as a soft/low energy ionization technique has enabled the analysis of large, intact biomolecules. Most mass spectrometry experiments consist of three main steps: ionization, probe step(s), and mass analysis. The present work focuses on a variety of methods for altering ion types at various stages of the mass spectrometry experiment to affect ion fragmentation. Ion types can be manipulated in the solution/droplet phases using novel nESI emitters, generated from borosilicate theta capillaries. These …

Go to article

Divide And Recombine For Large Complex Data: The Subset Likelihood Modeling Approach To Recombination, Philip Gautier Apr 2015

Divide And Recombine For Large Complex Data: The Subset Likelihood Modeling Approach To Recombination, Philip Gautier

Open Access Dissertations

Divide and recombine (D&R) is a statistical framework for the analysis of large complex data. The data are divided into subsets. Numeric and visualization methods, which collectively are analytic methods, are applied to each subset. For each analytic method, the outputs of the application of the method to the subsets are recombined. So each analytic method has associated with it a division method and a recombination method. Here we study D&R methods for likelihood-based model fitting. We introduce a notion of likelihood analysis and modeling. We divide the data and fit a likelihood model on each subset. The fitted model …

Go to article

International Water And Food Security Development: Performance Evaluation And Assessment Of Research Needs At Multiple Scales, Caitlin Anne Grady Apr 2015

International Water And Food Security Development: Performance Evaluation And Assessment Of Research Needs At Multiple Scales, Caitlin Anne Grady

Open Access Dissertations

Water and food security remain the top development challenges of the decade, and perhaps the century. Since the Millennium Development Goals were established in 2000, billions of people have obtained access to more food, better nutrition, improved water, and basic sanitation facilities worldwide. This progress has been accomplished through the dedication of international organizations, non-governmental organizations, country-level governments, private corporations, and individuals at international, regional, and local scales. Truly tremendous strides have been made in water and food provisioning for humans worldwide. These past two decades have also seen the largest population growth on record, the highest rates of childhood …

Go to article

First Prev Next Last