Estimating Microbial Population Data from Optical Density

The spectrophotometer has been used for decades to measure the density of bacterial populations using the turbidity expressed as optical density – OD. However, the OD alone is an unreliable metric and is only proportionately accurate to cell titers to about an OD of 0.6. The relationship between OD and cell titer depends on the configuration of the spectrophotometer, the length of the light path through the culture, the size of the bacterial cells, and the cell culture density. We demonstrate the importance of plate reader calibration to identify the exact relationship between OD and cells/ml. We use four bacterial genera and two sizes of micro-titer plates (96-well and 384-well) and show that the cell/ml per unit OD depends heavily on the bacterial cell size and plate size. We applied our calibration curve to real growth curve data and conclude the cells/ml – rather than OD – is a metric that can be used to directly compare results across experiments, labs, instruments, and species.

Meta-analysis for the Relationship Between Hyperuricemia and CVD Incidence

BACKGROUND: Uric acid was once considered an effective endogenous antioxidant, but now more and more evidence shows that it may play a significant role in the pathophysiology of cardiovascular diseases.OBJECTIVES: It has not been clear that UA is a sign of poor prognosis or a risk factor for CVD. Our aim is to figure out the exact relationship between CVD and uric acid. METHODS: We studied 3356 publications in the past 44 years through MEDLINE, EMBASE, and Cochrane library searches, and selected 22 studies that met our inclusion criteria. RESULTS: The meta-analysis showed that hyperuricemia was associated with an increased risk of death from CVD (RR=1.37; 95% CI:1.29-1.45; I2=31.4%, P=0.157). Sensitivity analysis reviewed several potential sources of heterogeneity between studies, such as average SUA level, study location, and outcome indicators.

Exploring the relationship between light and subjective alertness using personal lighting conditions

The discovery of the ipRGCs was thought to fully explain the mechanism behind the relationship between light and effects beyond vision such as alertness. However, this relationship turned out to be more complicated. The current paper describes, by using personal lighting conditions in a field study, further exploration of the relationship between light and subjective alertness during daytime. Findings show that this relationship is highly dependent on the individual. Although nearly all dose-response curves between personal lighting conditions and subjective alertness determined in this study turned out to be not significant, the results may be of high importance in the exploration of the exact relationship.

Zum variationslinguistischen Verhältnis von Stadt und Land.

In this paper, we explore the geolinguistic relationship between urban and rural areas through the conceptualisation and modeling of spatial topologies. Geolinguistic topologies concern the structure of the mutual linguistic relationship between localities. They can be defined either deductively or on the basis of empirical data and represent the linguistic similarities or distances between localities. We operationalise and apply several such topological models to Austrian data from the Atlas zur deutschen Alltagssprache (AdA), a linguistic atlas documenting colloquial German using crowd-sourcing methods. The results are evaluated on the basis of statistical examination and of visualisations of the topological relationships predicted by the models. It is confirmed that linguistic similarity is determined both by geographical distance and by the distribution of population, but the exact relationship is complex: Not only do smaller geographic distances on the one hand and higher population numbers on the other hand bring about increased linguistic similarity; the relevance of these two factors for linguistic similarity varies with population size, too, such that linguistic relationships between cities are determined more by their size and less by their distance, while for smaller locations the opposite is true. Hence, no single topological model can be identified as superior; instead, the individual models emphasise different aspects of the linguistic relationship between urban and regional language usage.

Neuronal sequences during theta rely on behavior-dependent spatial maps

Navigation through space involves learning and representing relationships between past, current and future locations. In mammals, this might rely on the hippocampal theta phase code, where in each cycle of the theta oscillation, spatial representations provided by neuronal sequences start behind the animal's true location and then sweep forward. However, the exact relationship between theta phase, represented position and true location remains unclear and even paradoxical. Here, we formalize previous notions of 'spatial' or 'temporal' theta sweeps that have appeared in the literature. We analyze single-cell and population variables in unit recordings from rat CA1 place cells and compare them to model simulations based on each of these schemes. We show that neither spatial nor temporal sweeps quantitatively accounts for how all relevant variables change with running speed. To reconcile these schemes with our observations, we introduce 'behavior-dependent' sweeps, in which theta sweep length and place field properties, such as size and phase precession, vary across the environment depending on the running speed characteristic of each location. These behavior-dependent spatial maps provide a structured heterogeneity that is essential for understanding the hippocampal code.

Assessments of bilateral asymmetry with application in human skull analysis

As a common feature, bilateral symmetry of biological forms is ubiquitous, but in fact rarely exact. In a setting of analytic geometry, bilateral symmetry is defined with respect to a point, line or plane, and the well-known notions of fluctuating asymmetry, directional asymmetry and antisymmetry are recast. A meticulous scheme for asymmetry assessments is proposed and explicit solutions to them are derived. An investigation into observational errors of points representing the geometric structure of an object offers a baseline reference for asymmetry assessment of the object. The proposed assessments are applicable to individual, part or all point pairs at both individual and collective levels. The exact relationship between the developed treatments and the widely used Procrustes method in asymmetry assessment is examined. An application of the proposed assessments to a large collection of human skull data in the form of 3D landmark coordinates finds: (a) asymmetry of most skulls is not fluctuating, but directional if measured about a plane fitted to shared landmarks or side landmarks for balancing; (b) asymmetry becomes completely fluctuating if one side of a skull could be slightly rotated and translated with respect to the other side; (c) female skulls are more asymmetric than male skulls. The methodology developed in this study is rigorous and transparent, and lays an analytical base for investigation of structural symmetries and asymmetries in a wide range of biological and medical applications.

Revision and Conditional Inference for Abstract Dialectical Frameworks

For propositional beliefs, there are well-established connections between belief revision, defeasible conditionals and nonmonotonic inference. In argumentative contexts, such connections have not yet been investigated. On the one hand, the exact relationship between formal argumentation and nonmonotonic inference relations is a research topic that keeps on eluding researchers despite recently intensified efforts, whereas argumentative revision has been studied in numerous works during recent years. In this paper, we show that similar relationships between belief revision, defeasible conditionals and nonmonotonic inference hold in argumentative contexts as well. We first define revision operators for abstract dialectical frameworks, and use such revision operators to define dynamic conditionals by means of the Ramsey test. We show that such conditionals can be equivalently defined using a total preorder over three-valued interpretations, and study the inferential behaviour of the resulting conditional inference relations.

FMRI and intra-cranial electrocorticography recordings in the same human subjects reveals negative BOLD signal coupled with silenced neuronal activity

Positive blood oxygenation level-dependent (BOLD) responses (PBR), as measured by functional Magnetic Resonance Imaging (fMRI), are the most utilized measurements to non-invasively map activity in the brain. Recent studies have consistently shown that BOLD responses are not exclusively positive. Negative BOLD responses (NBR) have been reported in response to specific sensory stimulations and tasks. However, the exact relationship between NBR and the underlying metabolic and neuronal demand is still under debate. In this study, we investigated the neurophysiological basis of negative BOLD using fMRI and intra-cranial electrophysiology (electrocorticography, ECoG) measurements from the same human participants. We show that, for those electrodes that responded to visual stimulation, PBR are correlated with high-frequency band (HFB) responses. Crucially, NBR were associated with an absence of HFB power responses and an unpredicted decrease in the alpha power responses.

Belief Fragments and Mental Files

Belief fragments and mental files are based on the same idea: that information in people’s minds is compartmentalized rather than lumped all together. Philosophers mostly use the two notions differently, though the exact relationship between fragments and files has yet to be examined in detail. This chapter has three main goals. The first is to argue that fragments and files, properly understood, play distinct yet complementary explanatory roles; the second is to defend a model of belief that includes them both; and the third is to raise and address a shared dilemma that confronts them: that they threaten to be either explanatorily lightweight or empirically refuted. This chapter contends that it is better to embrace the horn of this dilemma that opens up files and fragments to empirical refutation or confirmation, by adopting a psychofunctionalist approach.

A Brief Introduction to Regression Analysis and Its Types

This article may be used for research, teaching, and private study purposes. In this study, I focused on regression analysis and with a special focus on types of regression analysis and some types of regression. The term regression is used to indicate the estimation or prediction of the average value of one variable for a specified value of another variable. And Regression Analysis is a statistical tool used to estimate the relationship between a dependent variable and an independent variable. For example, if a Manger of a firm wants to the exact relationship between advertisement expenditure and sales for future planning then the regression technique will be most suitable for him.