Bayesian Modeling and MCMC Computation in Linear Logistic Regression for Presence-only Data

Presence-only data are referred to situations in which, given a censoring mechanism, a binary response can be observed only with respect to on outcome, usually called \textit{presence}. In this work we present a Bayesian approach to the problem of presence-only data based on a two levels scheme. A probability law and a case-control design are combined to handle the double source of uncertainty: one due to the censoring and one due to the sampling. We propose a new formalization for the logistic model with presence-only data that allows further insight into inferential issues related to the model. We concentrate on the case of the linear logistic regression and, in order to make inference on the parameters of interest, we present a Markov Chain Monte Carlo algorithm with data augmentation that does not require the a priori knowledge of the population prevalence. A simulation study concerning 24,000 simulated datasets related to different scenarios is presented comparing our proposal to optimal benchmarks.Comment: Affiliations: Fabio Divino - Division of Physics, Computer Science and Mathematics, University of Molise Giovanna jona Lasinio and Natalia Golini - Department of Statistical Sciences, University of Rome "La Sapienza" Antti Penttinen - Department of Mathematics and Statistics, University of Jyv\"{a}skyl\"{a} CONTACT: [email protected], [email protected]

Exploring the Link between System Integration and Technology Usage

Recent developments in the area of electronic accounting information systems have enabled accounting firms to move their focus from paper-based, mandatory business reporting and book-keeping to value-added services, such as providing cash flow forecasts to their customer companies (typically SMEs). In this study, we explore the usage of cash flow forecasting systems in accounting firms. Drawing on the theories of technology acceptance and usage and empirical data from 108 accounting firms, we find that system integration is a key determinant in explaining the task-technology fit which, in turn, explains the usage of cash flow forecasting systems. Further analysis revealed that frequent users of cash flow forecasting systems relied on commercial, highly integrated solutions, whereas ad hoc users preferred spreadsheet programs

Mobiilisovelluksen soveltuvuus rakennusliikkeen liikkuvan kenttätyön työajanseurantaan

Opinnäytetyön tarkoitus oli selvittää, mobiilisen työajanseurannan soveltuvuutta Rakennusliike Pekka Hämäläisen käyttöön. Työssä käydään läpi sovelluksen käyttöliittymän toimintaperiaatteet. Työssä testataan mobiilisten sovellusten toimintaa rakennusalan työajanseurantaan. Opinnäytetyössä pohditaan päätelaitteen valintaa sovelluksen käyttämiseen ja tuodaan esille, kuinka standardit vaikuttavat päätelaitteiden ominaisuuksiin. Päätelaitteiden osalta keskitytään koske-tusnäytöllisiin laitteisiin. Työ alkaa teoria osuudella, jossa käydään alan termistöä läpi. Työssä pyritään tuomaan asiat esille rakennusalan yrityksen kannalta ja keskitytään ohjelmiston soveltuvuuden valin-taan vaikuttaviin tekijöihin. Mobiilisovelluksista yritettiin tuoda esille ominaisuuksia ja mahdollisia puutteita heuristisella arvi-oinnilla. Heuristisen testin avulla löytyneistä ongelmista tehtiin parannusehdotuksia ohjelmisto-suunnittelijoille. Osalle työntekijöistä teetettiin kenttäolosuhteissa käyttäjätesti Movenium mobiili-sovelluksen kosketusnäyttösovelluksen käytöstä, älypuhelimen toimiessa päätelaitteena. Käyttötes-tissä työntekijöille pidettiin nopea perehdytys ennen sovelluksen käytön aloittamista. Käyttötestin jälkeen työntekijät täyttivät kyselykaavakkeen. Kyselykaavakkeella kartoitettiin käyttäjien ennakko-tiedot ja taidot älypuhelimista ja mobiilipohjaisista työajanseuranta ohjelmista. Käyttötestiin osallis-tuneet työntekijät suorittivat itsearvioinnin testikäytön onnistumisesta.The purpose of the study was to study the suitability of mobile time tracking for the use of Rakennusliike Pekka Hämäläinen. This work presents the principles for the application user interface. It also tests the suitability of mobile applications for monitoring construction working hours. The thesis includes consideration on choice of the terminal to run the application and highlights how standards affect the characteristics of the terminal devices. Terminal equipment section focuses mainly on touchscreen devices. The thesis starts with the theory part, which takes the reader through the terminology. The work aims to bring up the issues from a point of view of a construction company in terms of focusing on the suitability of the determining factors in the software selection. Heuristic evaluation was used for mobile applications to bring out the features which affect the use of application to find out any deficiencies. Software designers were informed about the problems found with the heuristic test for improvement. Some employees did a user test under field conditions using Movenium touchscreen mobile application with a smartphone operating as a terminal device. On the test, the workers were given a fast orientation before starting the use of the application. After the test, the workers filled in a questionnaire. The questionnaires were surveyed for previous knowledge and the skills on using smartphones and mobile-based work time tracking software. The employees participating in the test performed a self-assessment about the success of the test run

Second-harmonic generation of SESAM Q-switched microchip lasers

Pulsed laser sources are vital for a wide range of applications throughout the daily life. They are the key components in data transfer, medical use, industry as well as in variety of microscopic and spectroscopic applications. Novel microscopic and spectroscopic applications, such as photoacoustic microscopy or time-gated Raman spectroscopy require very specific pulsed laser sources. Even further, for many of these novel applications to reach a mature phase and foothold in our society, the light sources in use must come with affordable cost and compact footprint. The optical properties required in many applications feature a combination of short pulses, high pulse repetition rates, high energies and suitable operation wavelengths. Many of these properties define the application measurement time or imaging depth and thus the right combination of these is vital. For many novel applications requiring specific pulsed lasers, the options tend to be rather limited. Some solutions offer the required pulse repetition rates, enabling imaging speed and resolution, but are limited in pulse peak power, not generating imaging depth or targeted phenomena. Others can offer the correct optical parameters but the size or cost of such systems limits the applications. This issue of right combination of pulse parameters with a suitable technology platform was at the heart of this master thesis, with the focus on enabling novel imaging methods in the microscopic and spectroscopic applications. This thesis focuses on the development of a compact microchip laser sources at 1534 nm with optical properties targeted for photoacoustic microscopy use. Lasers studied take advantage of a semiconductor saturable absorber mirrors (SESAM) technology to offer a unique combination of parameters with ns pulse duration, high repetition rate from tens of kHz to hundreds of kHz and kW pulse peak power. These lasers were frequency doubled to 767 nm using second harmonic generation in periodically poled lithium niobate (PPLN) to offer novel wavelength regions with suitable pulse parameters

Sociotechnical Envelopment of Artificial Intelligence: An Approach to Organizational Deployment of Inscrutable Artificial Intelligence Systems

The paper presents an approach for implementing inscrutable (i.e., nonexplainable) artificial intelligence (AI) such as neural networks in an accountable and safe manner in organizational settings. Drawing on an exploratory case study and the recently proposed concept of envelopment, it describes a case of an organization successfully “enveloping” its AI solutions to balance the performance benefits of flexible AI models with the risks that inscrutable models can entail. The authors present several envelopment methods—establishing clear boundaries within which the AI is to interact with its surroundings, choosing and curating the training data well, and appropriately managing input and output sources—alongside their influence on the choice of AI models within the organization. This work makes two key contributions: It introduces the concept of sociotechnical envelopment by demonstrating the ways in which an organization’s successful AI envelopment depends on the interaction of social and technical factors, thus extending the literature’s focus beyond mere technical issues. Secondly, the empirical examples illustrate how operationalizing a sociotechnical envelopment enables an organization to manage the trade-off between low explainability and high performance presented by inscrutable models. These contributions pave the way for more responsible, accountable AI implementations in organizations, whereby humans can gain better control of even inscrutable machine-learning models

Cancer Risk Near a Polluted River in Finland

The River Kymijoki in southern Finland is heavily polluted with polychlorinated dibenzo-p-dioxins and dibenzofurans and may pose a health threat to local residents, especially farmers. In this study we investigated cancer risk in people living near the river (< 20.0 km) in 1980. We used a geographic information system, which stores registry data, in 500 m × 500 m grid squares, from the Population Register Centre, Statistics Finland, and Finnish Cancer Registry. From 1981 to 2000, cancer incidence in all people (N = 188,884) and in farmers (n = 11,132) residing in the study area was at the level expected based on national rates. Relative risks for total cancer and 27 cancer subtypes were calculated by distance of individuals to the river in 1980 (reference: 5.0–19.9 km, 1.0–4.9 km, < 1.0 km), adjusting for sex, age, time period, socioeconomic status, and distance of individuals to the sea. The respective relative risks for total cancer were 1.00, 1.09 [95% confidence interval (CI), 1.04–1.13], and 1.04 (95% CI, 0.99–1.09) among all residents, and 1.00, 0.99 (95% CI, 0.85–1.15), and 1.13 (95% CI, 0.97–1.32) among farmers. A statistically significant increase was observed for basal cell carcinoma of the skin (not included in total cancers) in all residents < 5.0 km. Several other common cancers, including cancers of the breast, uterine cervix, gallbladder, and nervous system, showed slightly elevated risk estimates at < 5.0 km from the river. Despite the limitations of exposure assessment, we cannot exclude the possibility that residence near the river may have contributed to a small increase in cancer risk, especially among farmers

Enhancing the axial resolution of an optoacoustic microscopy imaging instrument by using a pico-second pulse duration laser

In conventional optoacoustic microscopy, nanosecond pulse duration lasers are employed. When a laser delivering shorter pulse durations is used, it is expected that, from a theoretical point of view, broader, higher-frequency acoustic waves to be generated, therefore a better axial resolution of the instrument. In the present report, this advantage, offered by a picosecond duration pulse laser, to experimentally demonstrate that the axial resolution of an optoacoustic microscopy instrument can be enhanced was exploited. In comparison to a 2 ns pulse duration, an improvement in the axial resolution of ~50% is demonstrated by using excitations with pulses of duration <100 ps. Details of an optoacoustic microscopy instrument, operating at 532 nm, capable to provide high-resolution axial and lateral optoacoustic images, are also presented. The capabilities of the instrument are demonstrated by in-vivo images of Xenopus laevis brain with a similar ~3.8 µm lateral resolution throughout the whole axial imaging range