Parental investment decision rules: a test in bluegill sunfish

Summary We review parental investment decision theory and provide an experimental test of the decision rule used by male bluegill sunfish (Lepomis macrochirus) in allocating parental investment to their young. The alternative decision rules tested are: (1) invest according to brood size (number) only; (2) invest according to past investment only; (3) invest according to both brood size and past investment; and (4) invest according to neither brood size nor past investment. By manipulating brood size independently of a male's cumulative investment in the brood, and by measuring each male's defensive behavior against a model predator, we found that male bluegill invest according to both brood size and past investment. This result is consistent with recent theory that past parental investment devalues adult future reproductive value, and that animals should therefore invest according to the value of their brood relative to that of their own expected future reproduction.     

Behavior of cesium in fish tissues from Savannah River

A survey of cesium residues in fish from the Savannah River near the Savannah River Nuclear Plant was undertaken in 1983. Fish tissues, bone, fin, and muscle were incubated by the wet disgestion method for analysis. Seventeen fish samples were analyzed by flame atomic absorption spectrophotometry procedure to determine cesium content. It was found that cesium concentration levels were consistently higher in the bones and fins than in muscles of all fish species. It seems that cesium concentration levels were relatively higher in fins than in bones. Cesium concentration levels in muscle tissues were negligible in all fish species.     

A comparison of the particle track and α-spectrometric techniques in excess thorium-230 dating of Eastern Atlantic pelagic sediments

The particle track analysis and α-spectrometric techniques have been applied to a comparative study of excess ²³⁰Th dating of three deep-sea cores from the Eastern Atlantic. Both methods yield similar sediment accumulation rates. Limitations of the α-track phase of the particle track detection process, arising from the non-specific determination of ²³⁰Th and from the mobility of some alpha-emitting daughters, suggest that details of the sedimentation record may fail to be identified. The conventional radiochemical technique, on the other hand, specifically isolates all the radionuclides of interest but at the expense of a more complex experimental procedure and a longer sample processing time. The combined particle track technique (i.e. α and fission track analyses) therefore seems excellently suited to a complementary role in tandem with the α-spectrometric method of ²³⁰Th dating. Uranium determination by the fission track technique is accurate and rapid, showing good agreement with the α-spectrometric method.     

Trace elements in fish from the Savannah river near Savannah river nuclear plant

A survey of trace element residues in fish from the Savannah River near Savannah River Nuclear Plant was undertaken in 1982. Fish muscle tissue was incubated by the wet digestion method. Fifteen trace elements were determined by flame atomic absorption spectrophotometry analysi of the digests. It was found that As, Se, Mg, Hg, Ca, Zn, and Fe levels were relatively higher than Pb, Cd, Ni, Co, Cr, and Mn in all fish species. In addition, in all fish species it seems that Pb, Cd, Ni, Co, Cr, and Mn levels were relatively higher than Cs and Cu. Cs and Cu levels were negligible in all fish species analyzed. Trace element levels found in these fish species were not high enough to render them dangerous for human consumption.     

Prenatal diagnosis of the Klippel-Trenaunay-Weber syndrome

The Klippel-Trenaunay-Weber syndrome is a complex developmental disorder of the vascular and skeletal systems. While many features of the syndrome are congenital, it has not been diagnosed often before birth. This paper describes a case of Klippel-Trenaunay-Weber syndrome diagnosed at 19 weeks' gestation on the basis of sonographic findings and family history. The clinical variability of the syndrome is emphasized and the importance of family history in differential diagnosis is stressed.     

Risk factors associated with transcervical CVS losses

Factors found to be associated with pregnancy loss after transcervical CVS were race (higher for non-white), history of spontaneous abortion, unplanned pregnancy, history of spotting or bleeding during the pregnancy prior to CVS, and placental position (higher for fundal or lateral locations). Whether the increase in loss risk is due to the factor, per se, or the factor plus the CVS cannot be determined due to the lack of appropriate control data.     

Analysis of snake tissue and snake eggs for 2,3,7,8-tetrachlorodibenzo-p-dioxin via fused silica GC combined with atmospheric pressure ionization MS

Several snake tissue samples and one set of snake eggs were collected and analyzed for 2,3,7,8-tetrachlorodibenzo-$\text{p}$-dioxin. The isomer-specific analysis was performed using fused silica GC combined with atmospheric pressure ionization MS. The results ranged from a low of 38 parts-per-trillion (ppt) to high levels over 500 ppt.     

The crystal structure of octachlorodibenzodioxin: Experimental and calculated

The crystal structure of octachlorodibenzo-p-dioxin (OCDD) was determined and compared with the calculated geometry obtained by the semi-empirical modified neglect of diatomic overlap (MNDO) method. Experimental and calculated geometries for OCDD show excellent agreement.     

Effects of copper concentration on methane emission from rice soils

Outdoor pot experiments with various paddy soils representing five soil types were conducted at Nanjing Agricultural University during the 2000 and 2001 rice-growing seasons. Eighteen soils and ten out of the eighteen soils were involved in the 2000 and the 2001 experiment, respectively. Two treatments were designed as mineral fertilization (MF) and mineral fertilizer + wheat straw incorporation (MF + WS) for the 2001 experiment. Seasonal average rate of CH4 emission from different soils ranged from 1.96 to 11.06 mg m(-2) h(-1) in the 2000 experiment, and from 0.89 to 5.92 mg m(-2) h(-1) for the MF treatment in the 2001 experiment, respectively. Incorporation of wheat straw enhanced considerably CH4 emission with an average increment of 7.09 mg m(-2) h(-1). CH4 emissions from the two-year experiment were negatively correlated to soil available and total copper concentration. A further investigation showed that CH4 emission from the MF treatment was positively related to the dissolved organic carbon (DOC) in the soil (r = 0.904, p < 0.001), and that the DOC was negatively correlated to the concentrations of available copper (r = -0.844, p < 0.01) and total copper (r = -0.833, p < 0.01), respectively. Nevertheless, the incorporation of wheat straw did not enhance the soil DOC, and the relationship between CH4 emission and soil DOC was not statistically significant (r = 0.470, p < 0.20). It was concluded that higher concentration of copper in the soils resulted in lower soil DOC and thus reduced CH4 emission when there was no additional organic matter input. Incorporation of wheat straw did not affect soil DOC and available copper concentration but enhanced CH4 emission.