Improving the hydrobiological analysis of activated sludge at the Minsk wastewater treatment facilities

На основании накопленного опыта эксплуатации сооружений Минской очистной станции и обзора источников информации определена схема гидробиологического анализа активного ила, приведена форма регистрации результатов проведенного анализа. Для количественного учета нитчатых микроорганизмов разработана собственная пятибалльная система. Для нитчатых микроорганизмов, выявленных в активном иле, на основании анализа литературных данных определены условия, благоприятствующие их массовому развитию. В течение длительного периода времени, включающего разные сезоны года, проведена апробация усовершенствованной методики для мониторинга состояния иловой суспензии очистных сооружений двух площадок станции: классических четырехкоридорных аэротенков-вытеснителей первой площадки и биореакторов с каскадной денитрификацией второй площадки. Определены представители нитчатых микроорганизмов, постоянно обитающие в очистных сооружениях, выявлены доминирующие виды. Проведено сопоставление результатов анализа нитчатых форм и седиментационных характеристик активного ила. Сделаны заключения об особенностях биоценоза аэротенков первой площадки и биореакторов второй площадки, идентичности по видовому составу сообществ нитчатых бактерий, влиянии состава сточных вод и условий их очистки (нагрузка на ил, наличие зон с разным уровнем аэрации) на свойства иловой суспензии. Based on the accumulated experience in operating the Minsk Wastewater Treatment Facilities and a review of information sources, a scheme for the hydrobiological analysis of activated sludge was determined, and a form for recording the results of the analysis was provided. For the quantitative account of filamentous microorganisms, an original five-point system was developed. Based on the literature data analysis, favorable conditions for the mass growth of filamentous microorganisms found in activated sludge were determined. Over a long period of time, including different seasons of the year, the improved methodology was tested for monitoring the state of the sludge suspension at two sites of the treatment facilities: traditional four-line continuous-flow aeration tanks at the first site and bioreactors with cascade denitrification at the second site. The species of filamentous microorganisms, permanently living in wastewater treatment structures, have been identified, and the dominant species have been determined. The results of the analysis of filamentous forms and sedimentation characteristics of activated sludge are compared. Conclusions were made about the features of the biocenosis in the aeration tanks at the first site and in the bioreactors at the second site; about the identity of the species composition of the filamentous bacteria communities, the effect of the wastewater composition and treatment conditions (sludge load, occurrence of zones with different levels of aeration) on the properties of the sludge suspension.

Embedding in Shawi narrations: A quantitative analysis of embedding in a post-colonial Amazonian indigenous society

In this article, we provide the first quantitative account of the frequent use of embedding in Shawi, a Kawapanan language spoken in Peruvian Northwestern Amazonia. We collected a corpus of ninety-two Frog Stories (Mayer 1969) from three different field sites in 2015 and 2016. Using the glossed corpus as our data, we conducted a generalised mixed model analysis, where we predicted the use of embedding with several macrosocial variables, such as gender, age, and education level. We show that bilingualism (Amazonian Spanish-Shawi) and education, mostly restricted by complex gender differences in Shawi communities, play a significant role in the establishment of linguistic preferences in narration. Moreover, we argue that the use of embedding reflects the impact of the mestizo1 society from the nineteenth century until today in Santa Maria de Cahuapanas, reshaping not only Shawi demographics but also linguistic practices. (Post-colonial societies, Amazonian linguistics, Kawapanan, Shawi, embedding, language variation and change, contact linguistics)*

Quantifying self-quantification: A statistical study on individual characteristics and motivations for digital self-tracking in young- and middle-aged adults in Germany

This study presents a quantitative account of who uses or stops using digital self-tracking (ST). A representative sample of German adults aged 20–50 years ( N = 1022) completed an online survey on their ST practices, personality traits and attitudes toward numbers, on sociodemographic characteristics, mental disorders (particularly bulimia, burnout syndrome, and depression) and somatic disorders. A descriptive statistical analysis was performed on differences between self-trackers and non-trackers. Among others, they differ regarding age, civil status, social class, presence of mental and/or somatic diagnoses, performance-pressure, and strive for competition. A consequent binary logistic regression analysis suggests perfectionism, a somatic diagnosis within the last 5 years, a diagnosis of bulimia in the past, as well as a present mental diagnosis to be significant predictors for ST, though the predictive value of the factors was relatively low.

Prior expectations in visual speed perception predict encoding characteristics of neurons in area MT

Bayesian inference provides an elegant theoretical framework for understanding the characteristic biases and discrimination thresholds in visual speed perception. However, the framework is difficult to validate due to its flexibility and the fact that suitable constraints on the structure of the sensory uncertainty have been missing. Here, we demonstrate that a Bayesian observer model constrained by efficient coding not only well fits extensive psychophysical data of human visual speed perception but also provides an accurate quantitative account of the tuning characteristics of neurons known for representing visual speed. Specifically, we found that the population coding accuracy for visual speed in area MT ("neural prior") is precisely predicted by the power-law, slow-speed prior extracted from fitting the Bayesian model to the psychophysical data ("behavioral prior"), to the point that they are indistinguishable in a model cross-validation comparison. Our results demonstrate a quantitative validation of the Bayesian observer model constrained by efficient coding at both the behavioral and neural levels.

Bilinear magnetoresistance in HgTe topological insulator: opposite signs at opposite surfaces demonstrated by gate control

Spin-orbit effects appearing in topological insulators (TI) and at Rashba interfaces are currently revolutionizing how we can manipulate spins and have led to several newly discovered effects, from spin-charge interconversion and spin-orbit torques to novel magnetoresistance phenomena. In particular, a puzzling magnetoresistance has been evidenced, bilinear in electric and magnetic fields. Here, we report the observation of bilinear magnetoresistance (BMR) in strained HgTe, a prototypical TI. We show that both the amplitude and sign of this BMR can be tuned by controling, with an electric gate, the relative proportions of the opposite contributions of opposite surfaces. At magnetic fields of 1 T, the magnetoresistance is of the order of 1 \% and has a larger figure of merit than previously measured TIs. We propose a theoretical model giving a quantitative account of our experimental data. This phenomenon, unique to TI, offer novel opportunities to tune the electrical response of surface states for spintronics.

Degrees of riskiness, falsifiability, and truthlikeness

In this paper, we take a fresh look at three Popperian concepts: riskiness, falsifiability, and truthlikeness (or verisimilitude) of scientific hypotheses or theories. First, we make explicit the dimensions that underlie the notion of riskiness. Secondly, we examine if and how degrees of falsifiability can be defined, and how they are related to various dimensions of the concept of riskiness as well as the experimental context. Thirdly, we consider the relation of riskiness to (expected degrees of) truthlikeness. Throughout, we pay special attention to probabilistic theories and we offer a tentative, quantitative account of verisimilitude for probabilistic theories.

Metalogical Remarks on Induction

The problem of induction belongs to the most controversial issues in philosophy of science. If induction is understood widely, it covers every fallible inference, that is, such that its conclusion is not logically entailed by its premises. This paper analyses so-called reductive induction, that is, reasoning in which premises follow from the conclusion, but the reverse relation does not hold. Two issues are taken into account, namely the definition of reductive inference and its justification. The analysis proposed in the paper employs metalogical tools. The author agrees with the view that a quantitative account of degree of confirmation for universal theories via logical probability is problematic. However, prospect for a qualitative approach look as more promising. Using the construction of maximally consistent sets allows to distinguish good and worthless induction as well as shows how to understand induction in a semantic way. A closer analysis of deductivism in the theory of justification shows that it is a hidden inductivism.

Modeling speech act development in early childhood: the role of frequency and linguistic cues

A crucial step in children’s language development is the mastery of how to use language in context. This involves the ability to recognize and use major categories of speech acts (e.g., learning that a “question” is different from a “request”). The current work provides a quantitative account of speech acts’ emergence in the wild. Using a longitudinal corpus of child-caregiver conversations annotated for speech acts (Snow et al., 1996), we introduced two complementary measures of learning based on both children’s production and comprehension. We also tested two predictors of learning based on the input frequency and the speech acts’ quality of linguistic cues. We found that children’s developmental trajectory differed largely between production and comprehension. In addition, development in both of these dimensions was not explained with the same predictors (e.g., frequency in the child-directed speech was predictive of production, but not of comprehension). The broader impact of this work is to provide a computational framework for the study of communicative development where both measures and predictors of children’s pragmatic development can be tested and compared.

Bayesian confidence in optimal decisions

The drift diffusion model (DDM) provides an excellent account of decisions and response times. It also features the optimal property of tracking the difference in evidence between two options. However, the DDM struggles to account for human confidence reports, because responses are triggered when the difference in evidence reaches a set value, suggesting confidence in all decisions should be equal. Previously considered extensions to the DDM fall short of providing an adequate quantitative account of confidence. Possibly because of this, much confidence research has used non-normative models of the decision mechanism. Motivated by the idea that perceptual decision-making will reflect optimal computation, we consider 9 variants of the DDM. Motivated by the idea that the brain will not duplicate the representation of evidence, in all model variants confidence is read out from the decision mechanism. We compare the models to benchmark results, and make 4 qualitative predictions which we verify in a preregistered study. Modelling confidence on a trial-by-trial basis, we find that a subset of model variants provide an excellent account of the precise quantitative effects observed in confidence data. Specifically, models in which confidence reflects a miscalibrated Bayesian readout perform best. These results support the claim that confidence is based on the decision mechanism, which is itself optimal. Therefore, there is no need to abandon the idea that the implementation of perceptual decision-making will reflect optimal computation.