14 research outputs found
The world from a cat's perspective - statistics of natural videos
Abstract.: The mammalian visual system is one of the most intensively investigated sensory systems. However, our knowledge of the typical input it is operating on is surprisingly limited. To address this issue, we seek to learn about the natural visual environment and the world as seen by a cat. With a CCD camera attached to their head, cats explore several outdoor environments and videos of natural stimuli are recorded from the animals' perspective. The statistical analysis of these videos reveals several remarkable properties. First, we find an anisotropy of oriented contours with an enhanced occurrence of horizontal orientations, earlier described in the "oblique effectâ as a predominance of the two cardinal orientations. Second, contrast is not elevated in the center of the images, suggesting different mechanisms of fixation point selection as compared to humans. Third, analyzing a sequence of images we find that the precise position of contours varies faster than their orientation. Finally, collinear contours prevail over parallel shifted contours, matching recent physiological and anatomical results. These findings demonstrate the rich structure of natural visual stimuli and its direct relation to extensively studied anatomical and physiological issue
Hydroxyapatite-Based Solution as Adjunct Treatment for Biofilm Management: An In Situ Study
Synthetic hydroxyapatite-based solution is a bioinspired material that may present antiadhesive properties, restraining the dental biofilm formation without causing adverse effects. This
in situ study aims to evaluate the effects of three different hydroxyapatite (HAP) watery solutions
as a mouthwash against biofilm adhesion on different dental material surfaces under oral conditions. Hence, four volunteers carried maxillary splints containing enamel, titanium, ceramics, and
polymethyl-methacrylate resin (PMMA) samples. Three HAP watery solutions (5%) were prepared
with HAP particles presenting different shapes and sizes (HAP I, HAP II, HAP III). During 24 h, the
volunteers rinsed two times with one of the following selected tested solution: HAP I, HAP II, HAP
III, water, or chlorhexidine 0.2% (CHX). The first rinse was performed 3 min after pellicle formation;
the second rinse occurred after a 12 h interval. The surface analysis was performed by scanning
electron microscopy (SEM), fluorescence microscopy (FM), and transmission electron microscopy
(TEM). Statistical and microscopic analysis showed that most samples treated with any HAP solution
revealed reduced biofilm coverage presenting comparable results to CHX treated samples, however
without altering the microorganismsâ viability. In conclusion, the results of this investigation showed
that a pure hydroxyapatite-based mouthrinse could be a promising bioinspired adjunct solution for
biofilm management
Effectiveness of an intensive care telehealth programme to improve process quality (ERIC): a multicentre stepped wedge cluster randomised controlled trial
TRY plant trait database â enhanced coverage and open access
Plant traits - the morphological, anatomical, physiological, biochemical and phenological characteristics of plants - determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of traitâbased plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits - almost complete coverage for âplant growth formâ. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and traitâenvironmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
Non-Contact Eye-Tracking on Cats
The objective of visual systems neuroscience has shifted over the past few years from determining the receptive fields of cells towards the understanding of higher level cognition in awake animals viewing natural stimuli. In experiments with awake animals it is important to control the relevant aspects of behavior. Most important for vision science is the control of the direction of gaze. Here we present Dual Purkinje eye-tracking on cats, which---as a non-contact method --- brings a number of advantages. Along with the presented methods for calibration and for synchronization to off-the-shelf video presentation hardware, this method allows high precision experiments to be performed on cats freely viewing videos of natural scenes
The world from a cat's perspective: Statistics of natural videos
ISSN:0340-1200ISSN:1432-077
Direct and indirect effects of different dentifrices on the initial bacterial colonization of enamel in situ overnight
Objective: The aim of this study was to investigate the direct and indirect influence of fluoridated toothpastes and fluoride-free toothpaste with hydroxyapatite (HAP) as active ingredient on initial bacterial colonization on enamel in situ. Methods: For this clinical-experimental pilot study, eight subjects were instructed to brush their teeth with three different toothpastes (ElmexÂź: 1400 ppm AmF, MeridolÂź: 1400 ppm AmF +SnF2, KarexÂź: HAP), using each for two consecutive days. As a control, brushing without toothpaste was performed. To evaluate bacterial colonization, subject wore splints with buccally placed bovine enamel platelets overnight. Two modes were tested. In a first pass (regimen A), the splints were inserted after toothbrushing to examine the indirect effects of the dentifrices. In order to investigate the direct effects, the specimens were brushed in situ in a second pass (regimen B). Biofilm formation was visualized and quantified using fluorescence microscopy (DAPI and BacLight) and transmission electron microscopy (TEM).
Results: For brushing regimen A (indirect effect of dentifrices), no statistical differences were detected between any of the tested dentifrices or the control. Likewise, no statistically significant differences were recorded for brushing regimen B (direct effect of dentifrices). Furthermore, no differences between the different brushing techniques were determined with regard to the ultrastructure of the overnight biofilm. Conclusion: Within the limitations of the present pilot study, it can be concluded that in patients with good oral hygiene, dentifrices and their chemical composition have no statistically significant effect on the initial bacterial colonization of enamel platelets in situ, irrespectively of the mode of application
Impact of customary fuoride rinsing solutions on the pellicleâs protective properties and bioadhesion in situ
This study investigated the impact of customary fluoride based mouthrinses on the ultrastructure and the functional properties of the in situ pellicle, considering the prevention of erosion (8 volunteers) and initial biofilm formation (12 volunteers). Bovine enamel slabs were carried intraorally. After 1âmin of pellicle formation, the subjects rinsed with elmex Kariesschutz (A), Dontodent Med Care (B), meridol (C) or elmex Zahnschmelzschutz Professional (D) for 1âmin. In situ pellicle formation was continued up to 30âmin/8âh before processing the slabs in vitro. Erosion was simulated by incubating the specimens in HCl (pH 3.0, 2.3, 2.0) for 120âs, measuring the kinetics of calcium/phosphate release photometrically; representative samples were evaluated by TEM and EDX. Bacterial adhesion was visualized fluorescence microscopically (DAPI/BacLight). Native enamel slabs or physiological pellicle samples served as controls. All investigated mouthrinses enhanced the erosion preventive pellicle effect in dependence of the pH-value. A significant decrease of Ca/P release at all pH values was achieved after rinsing with D; TEM/EDX confirmed ultrastructural pellicle modifications. All mouthrinses tendentially reduced bacterial adherence, however not significantly. The mouthrinse containing NaF/AmF/SnCl2 (D) offers an effective oral hygiene supplement to prevent caries and erosion