In both humans and experimental animals, the ability to perceive contours that are vertically or horizontally oriented is superior to the perception of oblique angles. There is, however, no consensus about the developmental origins or functional basis of this phenomenon. Here, we report the analysis of a large library of digitized scenes using image processing with orientation-sensitive filters. Our results show a prevalence of vertical and horizontal orientations in indoor, outdoor, and even entirely natural settings. Because visual experience is known to inf luence the development of visual cortical circuitry, we suggest that this real world anisotropy is related to the enhanced ability of humans and other animals to process contours in the cardinal axes, perhaps by stimulating the development of a greater amount of visual circuitry devoted to processing vertical and horizontal contours.Humans and other animals process information at or near the vertical and horizontal meridians more efficiently than information projected onto the retina at oblique angles. This phenomenon-called the ''oblique effect''-has been documented by differences in acuity, contrast sensitivity, orientation discrimination, and recognition rate (1, 2). In addition to humans, species as diverse as octopuses, goldfish, rats, cats, and chimpanzees show the oblique effect to some degree (2). Despite the prevalence of this perceptual bias, there is little or no consensus about how or why it occurs or what significance it has for human vision (see, for example, ref.3).Although contours in the visual environment obviously are distributed across the full range of orientations, it is possible that the visual system has been biased functionally and structurally by a predominance of visible contours near the cardinal axes. In fact, natural vistas have predictable frequency and chromatic characteristics (4, 5), and an earlier study using optical Fourier analysis has shown that a variety of scenes have anisotropic frequency spectra, with more power near the cardinal axes (6; see also ref. 7). Despite these intriguing reports, the distribution of oriented feature contours projected onto the retina by representative objects has never been determined in a way that would allow ready comparison of the distribution of orientations within and between different visual environments. Accordingly, we have examined a large number of real world scenes, taking advantage of recent advances in image analysis to measure the distribution of oriented projections that the visual system must process. METHODSTo ensure an unbiased selection of scenes, we employed two naive subjects to collect representative images. The images were obtained with an automatic digital camera while the subjects walked about in three different settings: (i) indoor environments at Duke University; (ii) outdoor environments on the Duke University campus; and (iii) natural environments at Duke University (different regions of the Duke Forest, which comprises a variety of completely undevelo...

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Laparoscopic appendectomy has significant advantages over open appendectomy with respect to length of hospital stay, rate of routine discharge, and postoperative in-hospital morbidity.

This analysis suggests that rectal cancer patients treated by high-volume surgeons are five times more likely to undergo sphincter-sparing procedures than those treated by low-volume surgeon. This has significant implications for those seeking a sphincter-preserving option for the treatment of their rectal cancer.

Hypothesis: Laparoscopic colectomy has significant advantages over open colectomy in the treatment of diverticular disease with respect to the length of hospital stay, routine hospital discharge, and postoperative morbidity and mortality. Design: Retrospective secondary data analysis. Patients and Setting: Patients with primary International Classification of Diseases, Ninth Revision, Clinical Modification procedure codes for laparoscopic (709 patients [3.8%]) and open sigmoid resection (17735 patients [96.2%]) were selected from the 1998, 1999, and 2000 Nationwide Inpatient Samples. These databases represent 20% stratified probability samples of all US community hospital discharges. Sampling weights were used to allow generalization of the study findings to the overall US population. Multiple linear and logistic regression analyses were performed to assess the riskadjusted association between the surgery type and patient outcomes. Main Outcome Measures: Length of hospital stay, inhospital complications, in-hospital mortality, and the rate of routine discharge. Results: The patients had a mean age of 59.8 years; they were preponderantly white (89.1%) and female (54.0%). After adjusting for other covariates, laparoscopic sigmoidectomy was associated with a shorter mean hospital stay (laparoscopic sigmoidectomy vs open sigmoidectomy, 7.47 vs 9.37 days; PϽ.001), fewer gastrointestinal tract complications (odds ratio, 0.57; 95% confidence interval, 0.35-0.93; P=.03), a lower overall complication rate (odds ratio, 0.64; 95% confidence interval, 0.47-0.88; P=.007), and a higher routine hospital discharge rate (odds ratio, 2.21; 95% confidence interval, 1.51-3.21; PϽ.001). Conclusion: Laparoscopic sigmoid resection in patients with diverticular disease has statistically and clinically significant advantages over open sigmoid resection with respect to the length of hospital stay, rate of routine hospital discharge, and postoperative in-hospital morbidity.