SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Assumption of Mary

149

This study is dedicated to the environmental monitoring of radionuclides released in the course of the Fukushima nuclear accident. The activity concentrations of β(-) -emitting (90)Sr and β(-)/γ-emitting (134)Cs and (137)Cs from several hot spots in Japan were determined in soil and vegetation samples. The (90)Sr contamination levels of the samples were relatively low and did not exceed the Bq⋅g(-1) range. They were up four orders of magnitude lower than the respective (137)Cs levels. This study, therefore, experimentally confirms previous predictions indicating a low release of (90)Sr from the Fukushima reactors, due to its low volatility. The radiocesium contamination could be clearly attributed to the Fukushima nuclear accident via its activity ratio fingerprint ((134)Cs/(137)Cs). Although the correlation between (90)Sr and (137)Cs is relatively weak, the data set suggests an intrinsic coexistence of both radionuclides in the contaminations caused by the Fukushima nuclear accident. This observation is of great importance not only for remediation campaigns but also for the current food monitoring campaigns, which currently rely on the assumption that the activity concentrations of β(-)-emitting (90)Sr (which is relatively laborious to determine) is not higher than 10% of the level of γ-emitting (137)Cs (which can be measured quickly). This assumption could be confirmed for the samples investigated herein.

Concepts: Chernobyl disaster, Nuclear medicine, Concentration, Chemical equilibrium, HotSpot, Radioactive contamination, Lists of nuclear disasters and radioactive incidents, Assumption of Mary

32

The assumption that small changes in hydration status are readily compensated by homeostatic mechanisms has been little studied. In this study, the influence of hypohydration on cognition was examined.

Concepts: Homeostasis, Assumption of Mary

27

Concentrations of organically bound tritium (OBT) and tissue-free water tritium (TFWT, also referred to as HTO) in fruits and tubers were measured at a garden plot in the vicinity of the source of chronic airborne tritium emissions during the 2008, 2010, and 2011 growing seasons. A continuous record of HTO concentration in the air moisture was reconstructed from the continuous record of Ar-41 ambient gamma radiation, as well as from frequent measurements of air HTO by active samplers at the garden plot and Ar-41 and air HTO monitoring data from the same sector. Performed measurements were used for testing the modified Specific Activity (SA) model based on the assumption that the average air HTO during the pod-filling period provides an appropriate basis for estimating the levels of OBT present in pods, fruits and tubers. It is established that the relationship between the OBT of fruits and tubers and the average air HTO from a 15-20 day wide window centred at the peak of the pod-filling period is consistent throughout the three analysed years, and could be expressed by the fruit or tuber’s OBT to air-HTO ratio of 0.93 ± 0.21. For all three years, the concentration of HTO in fruits and tubers was found to be related to levels of HTO in the air, as averaged within a 3-day pre-harvest window. The variability in the ratio of plant HTO to air HTO appears to be three times greater than that for the OBT of the fruits and tubers. It is concluded that the OBT of fruits and tubers adequately follows an empirical relationship based on the average level of air HTO from the pod-filling window, and therefore is clearly in line with the modified SA approach.

Concepts: Plant, Measurement, Concentration, Ratio, Plant morphology, Tuber, Assumption of Mary, Tritium

26

SUMMARY The objective of a non-inferiority (NI) trial is to affirm the efficacy of a new treatment compared with an active control by verifying that the new treatment maintains a considerable portion of the treatment effect of the control. Compensation by benefits other than efficacy is usually the justification for using a new treatment, as long as the loss of efficacy is within an acceptable margin (NI margin) from the standard treatment. A popular approach is to express this margin in terms of the efficacy difference between the new treatment and the active control. Based on this approach and the realization that NI trials often comprise several new treatments, statistical procedures that simultaneously conduct NI tests of several new treatments have been developed. However, these procedures rely on the assumption that the variances of the treatments are homogeneous. In this paper, we discuss the undesirable effect of using these procedures on the familywise Type I error rate when the treatment responses have heterogeneous variances. To alleviate this problem, we reveal potential procedures that are more appropriate. Further, a power study is conducted to compare the different procedures to provide guidance on the selection of adequate testing procedures in NI trials. Clinical examples are given for illustrative purposes.

Concepts: Effectiveness, The Loss, Conducting, Assumption of Mary, Justification

22

The current article provides clinical conceptualizations of six dual-track interventions for dealing with stuck and resistant situations in hypnotherapy. Dual-track interventions are based on the assumption that patients habitually regard their problems as one-dimensional and thus, tend to become rigid in their attitudes toward these problems. Dual-track interventions constitute hypnotherapeutic processes for transforming patients' negative and rigid perceptions of their problems into more positive and functional mental states that provide a dual-dimensional view, thereby offering patients more options and freeing them to contend with their problems more effectively. We introduce a novel hypnotherapeutic tool from the Illness/Nonillness Model (Navon 2014). This tool, known as the differentiation tool, can transform negative perceptions of psychological and emotional conditions to positive and hopeful perceptions.

Concepts: Psychology, Cognition, Perception, Vector space, Real number, Transform, Absolute value, Assumption of Mary

17

Macroscopic models of brain networks typically incorporate assumptions regarding the characteristics of afferent noise, which is used to represent input from distal brain regions or ongoing fluctuations in non-modelled parts of the brain. Such inputs are often modelled by Gaussian white noise which has a flat power spectrum. In contrast, macroscopic fluctuations in the brain typically follow a 1/f(b) spectrum. It is therefore important to understand the effect on brain dynamics of deviations from the assumption of white noise. In particular, we wish to understand the role that noise might play in eliciting aberrant rhythms in the epileptic brain. To address this question we study the response of a neural mass model to driving by stochastic, temporally correlated input. We characterise the model in terms of whether it generates “healthy” or “epileptiform” dynamics and observe which of these dynamics predominate under different choices of temporal correlation and amplitude of an Ornstein-Uhlenbeck process. We find that certain temporal correlations are prone to eliciting epileptiform dynamics, and that these correlations produce noise with maximal power in the δ and θ bands. Crucially, these are rhythms that are found to be enhanced prior to seizures in humans and animal models of epilepsy. In order to understand why these rhythms can generate epileptiform dynamics, we analyse the response of the model to sinusoidal driving and explain how the bifurcation structure of the model gives rise to these findings. Our results provide insight into how ongoing fluctuations in brain dynamics can facilitate the onset and propagation of epileptiform rhythms in brain networks. Furthermore, we highlight the need to combine large-scale models with noise of a variety of different types in order to understand brain (dys-)function.

Concepts: Human brain, Cerebral cortex, Neurology, Correlation and dependence, Epilepsy, Seizure, Assumption of Mary

12

Research suggests a weaker sense of taste in people with obesity, with the assumption that this debilitated taste response increases the desire for more intensely tasting stimuli to compensate for decreased taste input. However, empirical testing of this supposition remains largely absent.

Concepts: Sensory system, Sense, Olfaction, Taste, Empirical research, Assumption of Mary, Ageusia, Supertaster

12

A long tradition of cultural evolutionary studies has developed a rich repertoire of mathematical models of social learning. Early studies have laid the foundation of more recent endeavours to infer patterns of cultural transmission from observed frequencies of a variety of cultural data, from decorative motifs on potsherds to baby names and musical preferences. While this wide range of applications provides an opportunity for the development of generalisable analytical workflows, archaeological data present new questions and challenges that require further methodological and theoretical discussion. Here we examine the decorative motifs of Neolithic pottery from an archaeological assemblage in Western Germany, and argue that the widely used (and relatively undiscussed) assumption that observed frequencies are the result of a system in equilibrium conditions is unwarranted, and can lead to incorrect conclusions. We analyse our data with a simulation-based inferential framework that can overcome some of the intrinsic limitations in archaeological data, as well as handle both equilibrium conditions and instances where the mode of cultural transmission is time-variant. Results suggest that none of the models examined can produce the observed pattern under equilibrium conditions, and suggest. instead temporal shifts in the patterns of cultural transmission.

Concepts: Scientific method, Mathematics, Frequency, Pattern, Logic, Equilibrium, Archaeology, Assumption of Mary

11

While neuroimaging studies typically collapse data from many subjects, brain functional organization varies between individuals, and characterizing this variability is crucial for relating brain activity to behavioral phenotypes. Rest has become the default state for probing individual differences, chiefly because it is easy to acquire and a supposed neutral backdrop. However, the assumption that rest is the optimal condition for individual differences research is largely untested. In fact, other brain states may afford a better ratio of within- to between-subject variability, facilitating biomarker discovery. Depending on the trait or behavior under study, certain tasks may bring out meaningful idiosyncrasies across subjects, essentially enhancing the individual signal in networks of interest beyond what can be measured at rest. Here, we review theoretical considerations and existing work on how brain state influences individual differences in functional connectivity, present some preliminary analyses of within- and between-subject variability across conditions using data from the Human Connectome Project, and outline questions for future study.

Concepts: Psychology, Brain, Activity, Behavior, Human behavior, Individual, Assumption of Mary, Individual differences psychology

11

Angiotensin-converting enzyme (ACE) plays a major role in blood pressure regulation and cardiovascular homeostasis. Contrary to the assumption that ACE levels are stable, circulating ACE has been shown to be altered in obesity and weight loss. We sought to examine effects of a high-saturated-fat (HF) diet on ACE within the NUtriGenomic Analysis in Twins (NUGAT) study.

Concepts: Protein, Nutrition, Blood, Obesity, Adipose tissue, Weight loss, Dieting, Assumption of Mary