Kindergartners' understanding of additive commutativity within the context of word problems.

Baroody and Gannon (1984) proposed that children's understanding of additive commutativity progresses through several levels of understanding based on a unary view of addition (change meaning) before developing a "true" level of understanding based on a binary conception (part-whole meaning). Resnick (1992) implied that children have both a unary and a binary conception of additive commutativity from the earliest stages of development. Fifty-three 5- and 6-year-old (M = 6-0) kindergartners' unary and binary understanding of additive commutativity was investigated using performance on tasks involving change-add-to and part-part-whole word problems, respectively. The data were inconsistent with the predictions of both models and suggest three alternate theoretical explanations. Moreover, the data indicate that success on a task involving change-add-to problems may be a more rigorous test of understanding of additive commutativity than that involving part-part-whole problems.

Using tasks to measure consumers' ability to apply food guide recommendations: lessons learned.

This article reports on lessons learned from using comparison and substitution tasks to assess consumers' ability to apply food guide messages. The study evaluated the usability of the Northeast Regional Food Guide (NERFG), which provides instruction on healthful diets of local foods in season. The tasks showed that the NERFG is useful for daily life decisions. Lessons learned were that the scores on tasks need to better differentiate between groups. The validity and reliability of the tasks should be established in future research. The use of tasks may also be appropriate for educational purposes.

Degeneration of afferent neurons and long-term stability of the ventilatory central pattern generator in chronically deafferented crabs.

1. The effects of chronic deafferentation, 3-180 days, are tested on the function and morphology of the crab (Carcinus maenas) ventilatory central pattern generator (CPGv). Almost all afferent axons are carried in the mixed sensory/motor levator nerve. The ability to speed the CPGv cycle rate by stimulating this nerve (Wilkens and DiCaprio 1994) decreases as the afferent neurons degenerate. Stimulation of the levator nerve eliminates motor units from the output even after 60 days of deafferentation, similar to the effects seen in acute preparations. 2. The 3 oval organ afferent axons of the levator nerve have central somata and survive scaphognathectomy. Impulses carried by these axons are known to inhibit the CPGv in acutely deafferented preparations and they are believed to be responsible for the persistent inhibition following small afferent degeneration seen here. 3. After 6 months of deafferentation the motor neuron collateral arborization densities within the thoracic ganglia are reduced, but all motor neurons appear to survive. These long-term deafferented CPGvs generate accurate motor patterns at similar rates to the control CPGv, but at reduced intraburst spike frequency. The crab CPGv is quite stable following chronic deafferentation.

Multiple enteroliths in a chronically obstructed duodenal loop after Roux-en-Y biliary diversion.

A case of chronic mechanical obstruction of the duodenal loop due to stricturing of the enteroenterostomy after diversion following a Polya gastrectomy for bile reflux gastritis is reported. The dilated loop contained several hundred enteroliths. The clinical and chemical evidence strongly supports the view that the enteroliths were formed in the intestinal loop. This complication of Roux-en-Y reconstruction has not previously been recognized.

A comparison between suction and corrugated drainage after simple mastectomy: a report of a controlled trial.

A randomized prospective trial of closed suction wound drainage compared with corrugated wound drainage after simple mastectomy for early breast cancer (lesion confined to the breast and without skin ulceration) is reported. Fifty-one patients were admitted to the study and there was no difference between the two groups with respect to local complications such as ifection, skin necrosis and collection under flaps and wound healing. Dressings require to be performed significantly less frequently with suction as opposed to corrugated drainage and suction drains were removed significantly sooner than corrugated drains. It is concluded that closed suction wound drainage should be used after simple mastectomy.

The action of sennosides and related compounds on human colon and rectum.

The direct action of intraluminal senna and related compounds on the human colon and rectum has been investigated. Motility was recorded by balloon kymography with recording units inserted into well established transverse colostomies or into the rectum. The motility of the colon was not changed by intraluminal senna glycosides but the introduction of senna previously incubated with faeces or Esch. coli stimulated the colon to peristalt. The peristalsis was similar to that stimulated by rheinanthrone, an oxanthrone produced by chemical hydrolysis and reduction of senna. Both activated senna and rheinanthrone appeared to act in the colon by contact stimulation. No peristaltic response was stimulated in the rectum, either with activated senna or with rheinanthrone.

Effects of neostigmine and atropine on motor activity of ileum, colon, and rectum of anaesthetized subjects.

In unanaesthetized patients atropine and neostigmine in doses normally used by anaesthetists to reverse muscle relaxants produced a pronounced increase in bowel activity. This response occurred whether atropine was given before or simultaneously with neostigmine.The response still occurred in 38% of patients anaesthetized without halothane, and possibly this increase in motility might endanger a recently constructed anastomosis. The ileum appeared particularly prone to neostigmine stimulation, and anastomoses involving ileum would seem especially at risk. When halothane was used during anaesthesia the response was completely inhibited during the period studied.