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 effect” 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

Treatment of Joint Prosthesis Infection in Accordance with Current Recommendations Improves Outcome

Background. Recently recommended treatment modalities for prosthetic joint infection (PJI) were evaluated. Methods. A retrospective cohort analysis of 68 patients with PJI of hip or knee who were treated from 1995 through 2004 was conducted at the University Hospital Bern (Bern, Switzerland). Results. A 2-stage exchange was the most frequent (75.0%) surgical strategy, followed by retention and/or debridement (17.6%), 1-stage exchange (5.9%), and resection arthroplasty or suppressive antimicrobial treatment (1.5%). The chosen strategy was in 88% agreement with the recommendations. Adherence was only 17% for retention and/or debridement and was 0% for 1-stage exchange. Most PJIs (84%) were treated with an adequate or partially adequate antimicrobial regimen. Recurrence-free survival was observed in 51.5% of PJI episodes after 24 months of follow-up. The risk of treatment failure was significantly higher for PJI treated with a surgical strategy other than that recommended (hazard ratio, 2.34; 95% confidence interval, 1.10-4.70; P=.01) and for PJIs treated with antibiotics not corresponding to recommendations (hazard ratio, 3.45; confidence interval, 1.50-7.60; P=.002). Other risk factors associated with lack of healing were a high infection score at the time of diagnosis (hazard ratio, 1.29; 95% confidence interval, 1.10-1.40; P<.001) and presence of a sinus tract (hazard ratio, 2.35; 95% confidence interval, 1.10-5.0; P=.02). Conclusions. Our study demonstrates the value of current treatment recommendations. Inappropriate choice of conservative surgical strategies (such as debridement and retention) and inadequate antibiotic treatment are associated with failur

Transmission Dynamics of Extended-Spectrum β-lactamase-Producing Enterobacteriaceae in the Tertiary Care Hospital and the Household Setting

Transmission of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in households outweighs nosocomial dissemination in the non-outbreak setting. Importation of ESBL producers into the hospitals is as frequent as transmission during hospital stay. ESBL-Klebsiella pneumoniae might be more efficiently transmitted within the hospital than ESBL-Escherichia col

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

Transmission dynamics of extended-spectrum β-lactamase-producing Enterobacteriaceae in the tertiary care hospital and the household setting

Studies about transmission rates of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae in hospitals and households are scarce