Anisotropies in visual motion perception: a fresh look

We measured motion-detection and motion-discrimination performance for different directions of motion, using stochastic motion sequences. Random-dot cinematograms containing 200 dots in a circular aperture were used as stimuli in a two-interval forced-choice procedure. In the motion-detection experiment, observers judged which of two intervals contained weak coherent motion, the other internal containing random motion only. In the direction-discrimination experiment, observers viewed a standard direction of motion followed by comparison motion in a slightly different direction. Observers indicated whether the comparison was clockwise or counterclockwise, relative to the standard. Twelve directions of motion were tested in the detection task and five standard directions (three cardinal directions and two oblique directions) in the discrimination task. Detection thresholds were invariant with direction of motion, but direction-discrimination thresholds were significantly higher for motion in oblique directions, even at low-coherence levels. Results from control conditions ruled out monitor artifacts and indicate that the oblique effect is relative to retinal coordinates. These results have broad implications for computational and physiological models of motion perception.     

Health-promoting behaviors of rural adolescent women

A part of a larger study of the health behaviors of adolescent women, this investigation examined health-promoting behaviors and the influence of cognitive, social, and environmental factors on these health-promoting behaviors of rural adolescent women. The sample consisted of 128 rural African-American and white adolescent women. Forty-four percent of the variance in health-promoting behavior of this sample was explained by five variables: self-image, problem solving, mother's education, employment status, and family structure. Self-image was the most salient predictor of health-promoting behavior, explaining 33% of the variance.     

A randomized controlled trial of filgrastim during remission induction and consolidation chemotherapy for adults with acute lymphoblastic leukemia: CALGB study 9111

Recombinant human granulocyte colony-stimulating factor (G-CSF; filgrastim) shortens the time to neutrophil recovery after intensive chemotherapy, but its role in the treatment of adults with acute lymphoblastic leukemia (ALL) is uncertain. We randomly assigned 198 adults with untreated ALL (median age, 35 years; range, 16 to 83) to receive either placebo or G-CSF (5 microgram/kg/d) subcutaneously, beginning 4 days after starting intensive remission induction chemotherapy and continuing until the neutrophil count was >/=1, 000/microL for 2 days. The study assignment was unblinded as individual patients achieved a complete remission (CR). Patients initially assigned to G-CSF then continued to receive G-CSF through 2 monthly courses of consolidation therapy. Patients assigned to placebo received no further study drug. The median time to recover neutrophils >/=1,000/microL during the remission induction course was 16 days (interquartile range [IQR], 15 to 18 days) for the patients assigned to receive G-CSF and 22 days (IQR, 19 to 29 days) for the patients assigned to placebo (P < .001). Patients in the G-CSF group had significantly shorter durations of neutropenia (<1, 000/microL) and thrombocytopenia (<50,000/microL) and fewer days in the hospital (median, 22 days v 28 days; P = .02) compared with patients receiving placebo. The patients assigned to receive G-CSF had a higher CR rate and fewer deaths during remission induction than did those receiving placebo (P = .04 by the chi-square test for trend). During Courses IIA and IIB of consolidation treatment, patients in the G-CSF group had significantly more rapid recovery of neutrophils >/=1,000/microL than did the control group by approximately 6 to 9 days. However, the patients in the G-CSF group did not complete the planned first 3 months of chemotherapy any more rapidly than did the patients in the placebo group. Overall toxicity was not lessened by the use of G-CSF. After a median follow-up of 4. 7 years, there were no significant differences in either the disease-free survival (P = .53) or the overall survival (P = .25) for the patients assigned to G-CSF (medians, 2.3 years and 2.4 years, respectively) compared with those assigned to placebo (medians, 1.7 and 1.8 years, respectively). Adults who received intensive chemotherapy for ALL benefited from G-CSF treatment, but its use did not markedly affect the ultimate outcome.     

Penicillin vs. erythromycin in the treatment of diphtheria

PURPOSE: To review the University of Florida experience in treating ependymomas, analyze prognostic factors, and provide treatment recommendations. METHODS AND MATERIALS: Forty-one patients with ependymoma and no metastases outside the central nervous system received postoperative radiotherapy with curative intent between 1966 and 1989. Ten patients had supratentorial lesions, 22 had infratentorial lesions, and 9 had spinal cord lesions. All patients had surgery (stereotactic biopsy, subtotal resection, or gross total resection). Most patients with high-grade lesions received radiotherapy to the craniospinal axis. Low-grade intracranial lesions received more limited treatment. Spinal cord lesions were treated using either partial spine or whole spine fields. RESULTS: Of 32 intracranial tumors, 21 recurred, all at the primary site; no spinal cord tumors recurred. Overall 10-year survival rates were 51% (absolute) and 46% (relapse-free); by tumor site: spinal cord, 100%; infratentorial, 45%; supratentorial, 20% (p = 0.002). On multivariate analysis, tumor site was the only factor that influenced absolute survival (p = 0.0004); other factors evaluated included grade, gender, age, duration of symptoms, resection extent, primary tumor dose, treatment field extent, surgery-to-radiotherapy interval, and days under radiotherapy treatment. CONCLUSIONS: Patients with supratentorial or infratentorial tumors receive irradiation, regardless of grade. Craniospinal-axis fields are used when spinal seeding is radiographically or pathologically evident. Spinal cord tumors are treated using localized fields to the primary site if not completely resected. Failure to control disease at the primary site remains the main impediment to cure.     

Sympathetic blockade of isolated rat hindlimbs by intra-arterial guanethidine: the effect on blood flow and arterial-venous shunting

In order to improve the understanding of the role of sympathetic nerve degeneration in reimplantation failure, the hindlimbs of eight rats (Group I) underwent near-complete amputation. The soft tissues of the hindlimb were transected at the proximal thigh with the femoral artery, vein and femur left intact. The femoral vessels were clamped and guanethidine was infused into a branch of the femoral artery of the right leg of each animal, while saline was injected into the left leg. The clamps were removed after 15 minutes. A baseline preoperative injection of radiolabeled microspheres was made, and subsequent injections at 6, 12, 18, and 24 hours postoperation. Twelve rats (Group II) were then used to assess the amount of arterial-venous shunting preoperatively (n = 6) and at 18 hours postoperation (n = 6), by venous sampling. Blood flow to both limbs increased postoperation, but there was significantly more flow in the guanethidine treated limb at 18 and 24 hours postoperation. The amount of shunting was approximately 50% in both limbs at 18 hours, as compared to 10% preoperation. These results highlight the potential benefit of guanethidine and other sympathetic blocking agents in reimplantation to increase blood flow, decrease tissue ischemia and increase anastomotic patency rates. They also suggest that sympathetic nerve degeneration did not affect the volume of arterial-venous shunting in this model, but the difference in blood flow was likely due to arteriolar vasospasm. Further study is needed to elucidate the clinical significance of sympathetic nerve degeneration in reimplantation failure.     

Wood-induced catalytic activation of PF adhesives autopolymerization vs. PF/wood covalent bonding

The reaction of polycondensation of phenol-formaldehyde (PF) resins in the presence of wood was confirmed to have a lower energy of activation than of the PF resin alone. Under the low temperature and short curing times characteristic of the application of PF resins as thermosetting wood adhesives DSC, TGA, chemical kinetics, and IR of PF resins and relevant model compounds were carried out. These indicated that two effects appear to be present when a PF resin cures on a wood surface, both induced by the polymeric constituents of the substrate, namely carbohydrates and lignin. These appear to be (1) the catalytic activation of the resin self-condensation induced particularly by carbohydrates such as crystalline and amorphous cellulose and hemicelluloses and (2) the formation of resin/substrate covalent bonding, particularly in the case of lignin. The first appears to be, by far, the major cause of the lowering of the activation energy of PF resins curing. The contribution of the second has been found to be very small and often negligble under the conditions pertaining to thermosetting wood adhesives applications. Molecular mechanics results appear to indicate that the marked catalytic activation of PF resins autocondensation and curing appears to be induced by the strong set of PF adhesive/substrate secondary forces interactions which appear to weaken bonds which, by cleavage, lead to PF resins autocondensation. © 1994 John Wiley & Sons, Inc.     

Co‐injection molding of PVC with other thermoplastics: Processing,properties, and applications

Rigid poly(vinyl chloride) (PVC) was co‐injected with glass‐fiber‐reinforced PVC (GFR‐PVC), polypropylene (PP), acrylonitrile‐butadiene‐styrene copolymer (ABS), and polycarbonate (PC) by using the Mono‐sandwich co‐injection process. Up to three through‐thickness skin‐core morphologies were observed along the length of the sample. Near the gate, the core was always a single, continuous layer. In some cases, the core diverged into multiple or discontinuous layers. Farther from the gate, flow of the core ceased, leaving a skin‐only region. The skin and core layers were more uniformly distributed through the test plaque when injection speed was low. Adhesion between PVC and PP was poor. Skin and core layers delaminated, and mechanical properties were poor. The PVC adhered well to GFR‐PVC, ABS, and PC. No layer delamination occurred, and mechanical properties were intermediate between those of the skin and core components alone. Dropped dart impact energy was controlled more by the skin layer than the core. In rigid PVC/GFR‐PVC co‐injected samples, impact energy was 2.5 times greater when GFR‐PVC was the core than when GFR‐PVC was the skin.