Universal precautions are not universally practiced by anesthesiologists.
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Anesthesiology↗
Biomedical subjects
E Greene
Publications and source records attributed to E Greene.
Probing collinearity bias in the close induction field.
The substrates of the Poggendorff illusion can be evaluated using as few as two line segments, a test segment whose collinearity is judged, and an induction segment which serves to bias that judgment. Previous research from this laboratory has shown that a very short induction segment can produce a substantial bias of perceived collinearity when it is centered at the tip of the test segment, and there is some evidence that the symmetry of this configuration affects the strength of this bias. Four experiments were conducted to clarify the issue of symmetry in the stimulation of the "half-field" zones which lie on each side of the tip. That Exp. 1a showed displacements which moved the induction segment to an eccentric position, i.e., occupying a single half-field, reduced collinearity error. With additional displacement which produced a gap there was a rebound of induction effect. Exp. 1b indicated that an eccentric induction segment does not produce the usual strength or pattern of bias as a function of its orientation relative to the test segment. Exp. 2a suggested that the strength of induction effect is a function of symmetry within the half-fields rather than the lengths of the segments per se. Finally, in Exp. 2b the strength of induction was a joint function of the position of a short segment within one half-field and the length of another segment which stimulated the other half-field. The effect showed a complex oscillation with changes in position. We discuss the induction mechanism as beginning with "contour filters" which register the induction segment(s) and which combine their responses on the basis of "tandem activation" of the close half-fields.
Form Perception↗
Anomalous and luminance contours produce similar angular induction effects.
One can shear a pattern of lines to produce an anomalous contour which has a perceptual influence similar to that of a straight line segment. Illusion effects have been found with configurations which contain these anomalous contours, as well as cross adaptation with respect to luminance contours. We have found that sheared-line contours will bias judgment of collinearity, ie perceived alignment, of a luminance contour. The angular induction effects are similar to those reported for interactions between luminance contours, and the same equation can be used to model both kinds of data. The results of this experiment support the neuroreductionist view that anomalous and luminance contours are processed at the same level of the nervous system. Additionally, we suggest that with both types of contour the perceptual system registers and responds to the alignment of local brightness differentials.
Adult↗
Angular induction as a function of the length and position of segments and gaps.
The perceptual distortions which are manifested in the Poggendorff illusion can be studied with the use of a more restricted set of stimulus elements. Experiments were designed in which angular induction effects between two line elements, known respectively as the test segment and induction segment, were evaluated. In some stimulus configurations the induction 'segment' consisted of a tandem pair of segments. Previous studies had shown that the induction segment will bias operant judgments of collinearity for a test segment, this effect being a function of the relative angle between the two. Six experiments are reported, in which the length and position of segments in relation to the tip of the test segment were varied. It was found that substantial induction is produced by a very short segment, and that this can bias judgment even when its displacement spans more than 10 deg of visual angle. Several aspects of the data suggest that the strength of effect is a log-linear function of segment position. However, the results from displacement of single or tandem segments do not conform to predictions based on length/response summation, and thus do not support a linear-systems approach. Neural substrates for these interactions are given brief attention.
Adult↗
Collinearity judgment as a function of induction angle.
The misalignment which is seen in the Poggendorff illusion can be studied with better control by using a configuration which has only two line segments. Two experiments were conducted in which subjects judged collinearity of a test segment, this judgment being subjected to a biasing influence from a second (induction) segment. Exp. 1 held the test segment at one of three orientations relative to the observer (30 degrees, 45 degrees, and 60 degrees) and systematically varied the orientation of the induction segment in 15 degrees increments through the range of possible positions. The orientation of the page relative to the observer was varied as well. Exp. 2 varied the test segment through a greater range of angles and sampled more levels of induction segment orientation. Analysis indicated that projection errors follow orderly rules similar in kind to but different in magnitude from those observed for the Tilt Illusion, most notably, (a) misprojection is greatest when the orientation of the interfering line is similar to that of the line segment being projected and (b) the strength of this influence decreases as the relative angle becomes orthogonal. Also, the orientation of the segment being projected relative to the observer serves to modulate the strength of the basic induction effect. These perceptual interactions are discussed in relation to neural models for orientation selectivity.
Adult↗
Classical geometric illusion effects with nonclassical stimuli: angular induction from decomposing lines into point arrays.
Angular induction is the process by which one line segment can bias judgment of orientation and/or collinearity of another segment, and it has been established that the magnitude of error is a determinate function of the relative angle between the two. We examined how these known relationships are affected by decomposing the induction segment into an array of scattered points. The bias that was produced by such arrays was found to be consistent with a formal model of angular induction, with the strength of the effect decreasing as the scatter among the points was increased. This decline in strength was almost linear with a logarithmic transform of the dimensions of the stimulus array. We also evaluated the hypothesis that the induction stimulus is detected by one or more channels--for example, neurons--for which the sensitivity profiles are modeled as Gabor wavelets. The change in induction strength with increasing point scatter was not predicted by a single width of channel. However, the combined activity of an ensemble of channels that differed in width did match the perceptual effects if one also stipulated that each channel would respond maximally to a fine-line stimulus.
Adult↗
Protective effects of anti-O polysaccharide and anti-lipid A monoclonal antibodies on pulmonary hemodynamics.
Monoclonal antibodies (MAbs) directed to endotoxin can protect in some animal models against the pathophysiological effects of endotoxin infusion. When 0.02 microgram/kg of lipopolysaccharide (LPS) derived from Escherichia coli O111:B4 was incubated in vitro for 2 h with the murine immunoglobulin G MAb, 5B10, directed against the O-polysaccharide antigenic domain of E. coli O111:B4 and then the mixture was infused into sheep, we noted significant protection. The second temperature peak was decreased (P < 0.05 vs. LPS control). The acute pulmonary arterial pressure elevation was diminished (mean peak pulmonary arterial pressure 23.2 +/- 2.5 mmHg, P < 0.05 vs. LPS control), and the peak plasma thromboxane B2 level was reduced (mean peak thromboxane B2 level 0.50 +/- 0.15 ng/ml, P < 0.05 vs. LPS control). In contrast, preincubation of the LPS with a human immunoglobulin M MAb, HA-1A, directed against the core glycolipid of the LPS molecule provided no protective effects in this sheep model. This finding is in agreement with recent studies reporting HA-1A may bind to antibiotic-treated bacteria but not to purified smooth LPS.
Animals↗
Protective effects of E5, an antiendotoxin monoclonal antibody, in the ovine pulmonary circulation.
The cross-protective effects of a murine immunoglobulin M monoclonal antilipid A antibody (E5 MAb) were tested by challenging awake sheep with mixtures of in vitro incubated E5 MAb (0.02 mg/kg) with lipopolysaccharide (LPS, 0.02 micrograms/kg) derived from Escherichia coli O111:B4, E. coli O55:B5, or Serratia marcescens. Intravenous infusion of these LPS preparations without antibody into awake sheep produced a similar pattern of fever, leukopenia, plasma thromboxane B2 (TxB2) release, and acute pulmonary vasoconstriction with pulmonary hypertension. The addition of MAb E5 to LPS from E. coli O111:B4 reduced these responses to the LPS in a fashion comparable to that achieved with an MAb specific to the E. coli O111:B4 O-side chain. Incubation of LPS derived from E. coli O55:B5 with the E5 MAb only slightly diminished acute pulmonary hypertension, the delayed temperature increase, and the degree of leukopenia (all P = NS) but reduced the mean peak TxB2 at 60 min (P < 0.05) compared with a control infusion of E. coli O55:B5 LPS. We were unable to demonstrate any protective effects on the pulmonary circulation from incubating E5 with LPS derived from S. marcescens. Preincubation of B55 MAb (a murine immunoglobulin M MAb directed against a human milk fat globulin), the control antibody, with LPS from E. coli 0111:B4 decreased the mean peak TxB2 but had no effect on the other parameters. We conclude that incubating E5 with LPS protects the pulmonary circulation of sheep from challenge with LPS derived from the parent E. coli strain. There were trends toward protection by E5 against LPS from 055:B5 E. coli, but these did not reach statistical significance.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Both tilt and misalignment are manifestations of angular induction.
With a Poggendorff configuration one sees two obliques as being misaligned, and with a Judd configuration one sees them as having different tilts, i.e., as being misoriented. It has been suggested that these are separate illusory effects. I submit, however, that one can see misorientation in the double Poggendorff and misalignment with a Judd-like configuration. It seems likely that both perceptual effects are manifestations of the same process.
Attention↗
Angular induction is modulated by the orientation of the test segment but not its length.
Angular induction is the basic process by which the orientation of line segments can affect the perceived orientation of other segments as well as their alignment. In this laboratory, we have found that the effect on alignment follows approximately linear rules, with the inducing segment having its greatest influence when its orientation is near to that of the segment being judged. Other laboratories, however, have reported peak effects when the relative angle between the two is at 45 degrees, and with the inducing segment being aligned with one of the cardinal axes of the observer. It has been said that the length of the test segment being judged is a critical factor, but the first experiment of the present study shows a similar linear decline of induction strength irrespective of test segment length. The second experiment indicates that the orientation of the test segment relative to the observer modulates the induction to determine the location of peak effects. A two-factor linear model predicts the observed pattern of results.
Adolescent↗
The influence of response factors on the magnitude of angular induction.
The angular induction which is manifested in geometric illusions such as the Poggendorff can be quantified by having the subject select a point which appears to be collinear to an oblique line segment. There may be some concern, however, that this operant procedure does not control the distance which is selected by the subject and may introduce nonperceptual sources of response bias. Four experiments, involving 14 subjects, provide evidence that the error, expressed as angular departure from true collinearity, is a constant irrespective of the location of the page which is chosen. Further, this operant procedure provides a valid measure of perceptual bias.
Adolescent↗
Control of interocular suppression as a function of differential image blur.
This experiment studied normal adults, normal children, and corrected strabismics with alternating fixation, evaluating their ability to detect information presented to one eye under viewing conditions which might affect their eye preference. An apparatus was used which allowed unconstrained, binocular viewing of a video monitor, but in which the image seen by one eye was blurred while that seen by the other eye was in sharp focus. Under these viewing conditions, subjects were asked to identify a sharply focused letter which was shown briefly to the eye which was seeing the blurred background image or to the one which was watching the well-focused image. The question was whether there would be general suppression of the eye that was shown a degraded background, causing a reduction in its ability to process other information being presented. The results indicate no performance penalty for children, a mild decrement in recognition accuracy for normal adults, and a severe deficit in the ability of corrected strabismics to attend to the eye which views a blurred image. These results suggest that the loss of binocular vision that accompanies childhood strabismus is not a result of an inherent sensitivity to blurring, insofar as such vulnerability is reflected by these acute testing conditions.
Adolescent↗
Juror and expert conceptions of battered women.
The admissibility of expert testimony at the trial of a battered woman defendant is very controversial. Some courts allow the testimony, others do not. This study focuses on two criteria judges use to determine admissibility and attempts to provide an empirical foundation that can assist their decisions. First, the area of study about which an expert testifies must be shown to be reliable and valid. Second, the subject matter of the testimony must be beyond the ken of the average juror. The first criterion was addressed by assessing the opinions of 45 researchers in the field of spousal violence. The second criterion was examined by evaluating the knowledge of 141 jurors about myths and empirical research findings associated with battered women. Results indicate that researchers showed strong consensus on 14 of 18 issues included in a survey about the reactions of abuse victims, and that compared to these "experts," jurors have limited knowledge on these issues. These results suggest that many of the scientific findings concerning battered women are reliable and that the information is often beyond the ken of the jury. The findings argue for the use of expert testimony in certain cases involving battered women defendants.
Attitude of Health Personnel↗
How judges sentence DUI offenders: an experimental study.
This study examined the impact of 1) a DUI offender's blood alcohol level at the time of arrest and 2) the number of prior drunken driving convictions on judges' sentencing patterns. These variables were manipulated using vignettes that were presented to all judges who sentence drunken drivers in Colorado. Judges were asked to determine appropriate amounts of jail time, fines, public service hours, and alcohol education course work. Results indicated that they gave more severe sentences to offenders with prior records and to those with higher blood alcohol levels. The effects were generally stronger for the first variable, prior record. These findings suggest that judges may perceive of and sentence repeat offenders differently than first-time offenders, regardless of the level of intoxication at arrest.
Accidents, Traffic↗
Use of segment arrays to evaluate the strength of angular induction.
The contribution of local and global influence on angular induction was evaluated by varying the orientation of individual segments that were organized into an array. It was found that some of the misprojection of an oblique is determined by the orientation of the individual segments, and some by the overall configuration of the segments into two parallel bands. These results are integrated into a model that views angular induction as a lateral bias among orientation-sensitive neurons, with global influence differing from local influence only as a matter of scale.
Adult↗
Angular induction as a function of contact and target orientation.
The Poggendorff effect is seen as misalignment of two obliques, or misprojection of one, when the obliques are placed outside a set of parallel lines. To understand better the mechanisms behind this effect, the orientation of the lines which are normally parallel was systematically manipulated. The results indicate that projection bias is affected by the orientation of either line, is at a minimum where the line is orthogonal to the oblique, and is maximal at small angles. This is in line with classic theories which attribute the illusion to misperception of angular size. However, such explanations presuppose that in order to be effective the induction line must be proximal to the oblique so that an angle can be formed. Results are reported which show that the angle formed by the oblique and a line placed at a distance from the oblique, serving as the target of the projection, follows an angular rule of effectiveness similar to what is seen when the line is placed directly in contact with the oblique. The underlying process is described as 'angular induction'.
Adult↗
Tolerance to low-dose endotoxin in awake sheep.
Dose response and tolerance to a small intravenous dose of Serratia marcescens lipopolysaccharide (LPS) were studied in awake sheep. Core temperature significantly increased after a dose of 0.002 micrograms/kg; changes in pulmonary arterial pressure, pulmonary vascular resistance, plasma thromboxane B2, and circulating leukocyte concentration occurred after 0.02 micrograms/kg; plasma 6-keto-prostaglandin F1 alpha increased after 0.2 micrograms/kg. Development of acute tolerance was studied by injection of S. marcescens LPS (0.02 micrograms/kg iv) on 3 consecutive days: pulmonary arterial pressure and thromboxane B2 levels were significantly lower than controls after the second dose, whereas fever and the degree of leukopenia were not diminished until the third dose. After intravenous administration of LPS given in increasing doses from 0.1 to 3.2 micrograms/kg three times weekly over 7 wk, there were no measurable changes in any of the above parameters after challenge with S. marcescens LPS (0.02 micrograms/kg) after a 1-wk rest period. In awake sheep, small intravenous doses of LPS can cause physiologically important changes of the pulmonary circulation and can alter the hemodynamic and eicosanoid mediator responses to subsequent challenges with LPS. Large intravenous doses of LPS can ablate the physiological responses to subsequent small doses of LPS.
Animals↗
Nafamstat mesilate attenuates pulmonary hypertension in heparin-protamine reactions.
Rapid protamine reversal of heparin anticoagulation in awake sheep caused, after 1 min, a approximately 15-fold increase of arterial plasma thromboxane B2 (TxB2) levels, a 4-fold rise of pulmonary vascular resistance (PVR), a 2-fold rise of pulmonary arterial pressure, and after 3 min, a 2-fold rise of ovine arterial plasma complement C3a levels (P less than 0.05). Infusion of nafamstat mesilate (FUT-175), a protease and complement pathway inhibitor, before protamine reduced these increases by approximately 60-90% (P less than 0.05). FUT-175 did not modify heparin + protamine-induced leukopenia, suggesting that FUT-175 incompletely blocked C5a production. We also learned that infusing protamine first and heparin 5 min later did not increase either plasma C3a or TxB2 levels or PVR while the activated clotting time increased only minimally. Thus, in awake sheep, the sequence of heparin and protamine infusion influences complement activation and pulmonary vasoconstriction. FUT-175 pretreatment reduces thromboxane release and pulmonary vasoconstriction probably by limiting complement activation.
Animals↗