scholarly journals Discriminative Bayesian Serology: Counting Without Cutoffs

Author(s):  
Murray Christian ◽  
Ben Murrell

AbstractDuring the emergence of a pandemic, we need to estimate the prevalence of a disease using serological assays whose characterization is incomplete, relying on limited validation data. This introduces uncertainty for which we need to account.In our treatment, the data take the form of continuous assay measurements of antibody response to antigens (eg. ELISA), and fall into two groups. The training data includes the confirmed positive or negative infection status for each sample. The population data includes only the assay measurements, and is assumed to be a random sample from the population from which we estimate the seroprevalence.We use the training data to model the relationship between assay values and infection status, capturing both individual-level uncertainty in infection status, as well as uncertainty due to limited training data. We then estimate the posterior distribution over population prevalence, additionally capturing uncertainty due to finite samples.Finally, we introduce a means to pool information over successive time points, using a Gaussian process, which dramatically reduces the variance of our estimates.The methodological approach we here describe was developed to support the longitudinal characterization of the seroprevalence of COVID-19 in Stockholm, Sweden.

2021 ◽  
Vol 40 (7) ◽  
pp. 534-542
Author(s):  
Ricard Durall ◽  
Valentin Tschannen ◽  
Norman Ettrich ◽  
Janis Keuper

Interpreting seismic data requires the characterization of a number of key elements such as the position of faults and main reflections, presence of structural bodies, and clustering of areas exhibiting a similar amplitude versus angle response. Manual interpretation of geophysical data is often a difficult and time-consuming task, complicated by lack of resolution and presence of noise. In recent years, approaches based on convolutional neural networks have shown remarkable results in automating certain interpretative tasks. However, these state-of-the-art systems usually need to be trained in a supervised manner, and they suffer from a generalization problem. Hence, it is highly challenging to train a model that can yield accurate results on new real data obtained with different acquisition, processing, and geology than the data used for training. In this work, we introduce a novel method that combines generative neural networks with a segmentation task in order to decrease the gap between annotated training data and uninterpreted target data. We validate our approach on two applications: the detection of diffraction events and the picking of faults. We show that when transitioning from synthetic training data to real validation data, our workflow yields superior results compared to its counterpart without the generative network.


2017 ◽  
Vol 30 (71) ◽  
Author(s):  
Gerardo Macario Pantoja Zavala ◽  
Felipe Flores Vichi

El objetivo del estudio es identificar a los productores y comercializadores del sistema citrícola de Nuevo León, para integrarlos al sector agroindustrial a partir de los procesos del enfoque metodológico de los sistemas agroalimentarios localizados. Con la teoría de los distritos agroindustriales y un análisis previo de la región con perspectiva histórica, geográfica, productiva y de relación entre los actores, de acuerdo con el esquema productivo, se podrá medir la articulación de éstos en virtud de sus atributos y diferencias, lo que creará condiciones de competitividad en el sector citrícola, y generará unidades empresariales basadas en la equidad y el manejo pertinente de los recursos naturales encaminados a las generaciones venideras. Los estudios sobre agricultura regional contribuyen a establecer la seguridad alimentaria, la estabilidad laboral y el desarrollo territorial y ambiental, según la premisa del desarrollo sustentable.Nuevo Leon’s citrus sector: characterization of the agri-food system as a platform for integration of the producer with agro-industryThe aim of the study is to identify the producers and marketers in Nuevo Leon’s citrus system in order to integrate them into the agro-industrial sector on the basis of the processes of the methodological approach to the localized agri-food systems. Using the agro-industrial districts theory and through a prior analysis of the region from a historical, geographical, productive perspective and taking into consideration the relationship among actors, according to the productive scheme, it will be possible to measure the interconnection among these by virtue of their attributes and differences. This will create competitive conditions in the citrus sector and generate business units based on equity and the appropriate management of natural resources destined to future generations. Studies on regional agriculture contribute to food security, job stability and territorial and environmental development, according to the sustainable development premise.


Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Author(s):  
A.K. Rai ◽  
A.K. Petford-Long ◽  
A. Ezis ◽  
D.W. Langer

Considerable amount of work has been done in studying the relationship between the contact resistance and the microstructure of the Au-Ge-Ni based ohmic contacts to n-GaAs. It has been found that the lower contact resistivity is due to the presence of Ge rich and Au free regions (good contact area) in contact with GaAs. Thus in order to obtain an ohmic contact with lower contact resistance one should obtain a uniformly alloyed region of good contact areas almost everywhere. This can possibly be accomplished by utilizing various alloying schemes. In this work microstructural characterization, employing TEM techniques, of the sequentially deposited Au-Ge-Ni based ohmic contact to the MODFET device is presented.The substrate used in the present work consists of 1 μm thick buffer layer of GaAs grown on a semi-insulating GaAs substrate followed by a 25 Å spacer layer of undoped AlGaAs.


2006 ◽  
Vol 18 (4) ◽  
pp. 160-173 ◽  
Author(s):  
Maria Senokozlieva ◽  
Oliver Fischer ◽  
Gary Bente ◽  
Nicole Krämer

Abstract. TV news are essentially cultural phenomena. Previous research suggests that the often-overlooked formal and implicit characteristics of newscasts may be systematically related to culture-specific characteristics. Investigating these characteristics by means of a frame-by-frame content analysis is identified as a particularly promising methodological approach. To examine the relationship between culture and selected formal characteristics of newscasts, we present an explorative study that compares material from the USA, the Arab world, and Germany. Results indicate that there are many significant differences, some of which are in line with expectations derived from cultural specifics. Specifically, we argue that the number of persons presented as well as the context in which they are presented can be interpreted as indicators of Individualism/Collectivism. The conclusions underline the validity of the chosen methodological approach, but also demonstrate the need for more comprehensive and theory-driven category schemes.


2006 ◽  
Author(s):  
Jaclyn S. Turner ◽  
Kristen Fox ◽  
David Pincus

2019 ◽  
Author(s):  
Liwei Cao ◽  
Danilo Russo ◽  
Vassilios S. Vassiliadis ◽  
Alexei Lapkin

<p>A mixed-integer nonlinear programming (MINLP) formulation for symbolic regression was proposed to identify physical models from noisy experimental data. The formulation was tested using numerical models and was found to be more efficient than the previous literature example with respect to the number of predictor variables and training data points. The globally optimal search was extended to identify physical models and to cope with noise in the experimental data predictor variable. The methodology was coupled with the collection of experimental data in an automated fashion, and was proven to be successful in identifying the correct physical models describing the relationship between the shear stress and shear rate for both Newtonian and non-Newtonian fluids, and simple kinetic laws of reactions. Future work will focus on addressing the limitations of the formulation presented in this work, by extending it to be able to address larger complex physical models.</p><p><br></p>


2016 ◽  
pp. 15
Author(s):  
Mariana Giaretto ◽  
Victoria Naffa

ResumenEn este trabajo analizamos las relaciones entre tomas de tierras y Estado, en elAlto Valle de Río Negro en Argentina. En un contexto general de especulacióninmobiliaria, por la que se encarecen los precios de alquileres y terrenos, y depolíticas de vivienda selectivas y acotadas, los sectores populares acceden aun espacio en la ciudad mediante tomas de tierras. Frente a estos conflictos,el Estado, en sus diferentes niveles y poderes, despliega una forma deintervención basada en la criminalización de las luchas por tierra y vivienda.Al mismo tiempo, el poder ejecutivo nacional crea la Secretaría de Acceso alHábitat, para posibilitar la intervención política orientada a la regularizaciónde los asentamientos. Sin embargo, esta intervención tiende a reinscribir laproblemática habitacional en el campo político, para reducirla a un conflicto“entre partes”, eludiendo la responsabilidad estatal.Desde un enfoque metodológico cualitativo, seleccionamos como referenteempírico el caso del asentamiento de Villa Obrera en Fiske, Menuco (Gral.Roca), y las técnicas de recolección de datos se basan en fuentes secundarias,como expedientes judiciales y normativa, y en fuentes primarias como son losrelatos de los protagonistas mediante entrevistas individuales y colectivas.Palabras clave: tomas de tierras, Estado, criminalización de los conflictos.Conflicts caused by land occupation and modesof State intervention: analysis of an experience ofAlto Valle in Río Negro (Argentina)AbstractThis paper analyzes the relationship between State and land occupation,at Alto Valle in Río Negro, Argentina. In a general context of real estatespeculation, where rents and land prices are expensive, and a policy ofselective and limited housing, popular sectors can have access to a spacein the city through land occupation. In front of these conflicts, the Statein its different levels and powers, displays a form of intervention basedon the criminalization of struggles for land and housing. At the sametime, the national executive creates the Secretariat of Access to Habitat,oriented to allow political intervention for the regularization of settlements.However, this intervention tends to re-register the housing problems in thepolitical arena, reducing it to a conflict “between parties” and eluding theresponsibility of the State.From a qualitative methodological approach, we selected as empirical referencethe case of the settlement of Villa Obrera in Fiske, Menuco (GeneralRoca). The techniques of data collection are based on secondary sources, suchas policy and legal records, and primary sources as the stories of protagoniststhrough individual and collective interviews.Keywords: land occupation, State, criminalization of conflicts.Conflitos sobre ocupações de terras e modos deintervenção do estado: análise de uma experiênciado Alto Valle do Rio Preto (Argentina)ResumoEste trabalho analisa as relações entre a posse de terra e o Estado, no AltoValle do Rio Preto, na Argentina. Num contexto geral da especulaçãoimobiliária, por qual se encarecem os preços do aluguel e das terras, e depolíticas de habitação seletivas e limitadas, os setores populares acedem aum espaço na cidade através de ocupações de terras. Frente a estes conflitos,o Estado, em seus diferentes níveis e poderes, desenvolve uma forma deintervenção com base na criminalização das lutas pela terra e vivenda. Aomesmo tempo, o poder executivo nacional cria a Secretaria de Acesso àHabitat para possibilitar à intervenção política orientada a regularização dosassentamentos. No entanto, esta intervenção tende a registrar os problemasde habitação no campo político, para reduzi-la a um conflito “entre aspartes”, iludindo a responsabilidade do Estado.A partir de uma abordagem metodológica qualitativa, foi selecionado comoreferência empírica o caso do Assentamento de Villa Obrera em Fiske,Menuco (Gral. Roca), e as técnicas de recolecção de dados são baseados emfontes secundárias, como expedientes judiciais e normativos, e em fontes primárias como são as histórias dos protagonistas através de entrevistasindividuais e coletivas.Palavras-chave: tomada de terras, Estado, criminalização dos conflitos.


Author(s):  
Bibian Bibeca Bumbila García ◽  
Hernán Andrés Cedeño Cedeño ◽  
Tatiana Moreira Chica ◽  
Yaritza Rossana Parrales Ríos

The objective of the work is to establish the characterization of the auditory disability and its relationship with resilience at the Technical University of Manabí. The article shows a conceptual analysis related to the inclusion and social integration of disabled students. Based on the fact that the person with disabilities grows and develops in the same way as that of people without disabilities and what usually happens is that disabled people are rejected and discriminated against based on a prefabricated and erroneous conceptualization of these people. The results associated with the application of the SV-RES test prepared by the researchers are shown (Saavedra & Villalta, 2008b). Characterization of the auditory deficit is made in the students, and the limitations that derive from it are pointed out. We analyze the particularities related to communication with students who have a hearing disability and resilience in this type of student, where some personal highlights that in this sense constitute an example of resilience. Finally, the results related to the study of the relationship between students' hearing disability and the level of resilience dimensions are shown.


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