Microstructural Evolution in Annealed and Crept Silicon Nitride

The microstructure of a commercial sintered silicon nitride has been examined in the as-sintered condition, after annealing to a stable microstructure in either air or argon, and after creep deformation. Both as-sintered material and material annealed to a stable microstructure were crept. Extensive analytical electron microscopy has been used to determine the composition of the intergranular material (amorphous and crystalline). The as-sintered material contains an amorphous intergranular phase which partially devitrifies upon exposure to high temperatures. The residual intergranular glass is homogeneous throughout the samples (even though different crystalline products form near the surface and in the center of samples annealed in air) and stable. Creep deformation does not affect the microstructural evolution. It is, however, responsible for internal strain and some cavitation in the material.     

A technique for measuring bronchial mucociliary clearance in unsedated dogs

An unsedated dog model of bronchial mucociliary clearance was developed using radioaerosol techniques. A neutralized, concentrated, monodisperse iron oxide aerosol (5–6 μm MMAD) radiotagged with technetium-99m was delivered to the dog via a face mask. Retained activity was measured while the dog was restrained in front of a gamma camera. Measurements were made for 2–3 h post-inhalation and again at 24 h. Three beagle dogs, each studied four times, demonstrated mean percents for 2 h particle retention within the whole lung of 76 ± 13, 92 ± 7 and 89 ± 4, within the bronchial airways of 48 ± 27, 84 ± 15 and 73 ± 10, and mean 24 h particle retentions of 47 ± 18, 65 ± 11 and 57 ± 9, respectively. The unsedated beagle dog provides a potential model for study of the effects of drugs, disease and inhaled pollutants on mucociliary transport.     

Double-crested Cormorant (Phalacrocorax auritus) chick bioenergetics following round goby (Neogobius melanostomus) invasion and implementation of cormorant population control

As the fish community changed in the Beaver Archipelago (northern Lake Michigan), so has the diet of breeding Double-crested Cormorants (Phalacrocorax auritus). In 2000, the energetically dense alewife (Alosa pseudoharengus) dominated the diet, but more recently, the relatively low quality round goby (Neogobius melanostomus) has become the most common prey item. Additionally, cormorant control measures have been underway in the archipelago. This study investigated decreases in cormorant chick numbers and changes in chick bioenergetics in response to this change in diet, as well as the influence of control efforts, and compared these results to an earlier study. Two colonies, one actively controlled the other only controlled following completion of this study, were investigated to determine changes in colony size throughout the breeding season, document chick diet, measure chick growth, and determine chick survivorship to fledging. The bioenergetics model estimated that in 2010, chicks consumed a greater biomass of prey to reach fledging due to the change in diet, but lower biomass overall due to fewer chicks in the system. Control efforts in combination with the change in diet reduced chick numbers. Overall, the impact of cormorant chicks on available fish biomass has declined in recent years due to control efforts. However, the birds have the potential to consume a greater biomass of round goby in the absence of control. The impact of cormorants on fisheries resources is complicated by the abundance and effects of non-native species.     

Assessment of fish mercury levels in the upper St. Lawrence River,Canada

The stretch of the St. Lawrence River near Cornwall, Ontario, Canada, between the Moses–Saunders power dam to the eastern outlet of Lake St. Francis in Québec, is currently listed as an Area of Concern (AOC), and has restrictive fish consumption advisories in place, largely due to high mercury levels. This study examined long-term temporal trends of mercury concentrations in northern pike, smallmouth bass, walleye and yellow perch from the St. Lawrence River, including the Cornwall AOC. In addition, differences in fish mercury concentrations among river sections were compared for each species using historical (1975–1979) and recent (2000–2011) data. Statistically significant declines in mercury concentrations were observed in all river sections for yellow perch (~ 40%), as well as in northern pike and walleye in at least one river section. For the river section encompassing the AOC, recent mercury concentrations are 33–59% lower than historical mercury concentrations for all four species. Further, a comparison of recent mercury concentrations between the AOC river section and other Ontario lakes/rivers suggests that AOC mercury values are within the 75th percentile of values for other Ontario water bodies in three of the four species considered. However, current fish mercury values for the AOC river section remain higher than one or more upstream river sections. These results indicate that recovery is still ongoing in this AOC.     

Obesogenic Diet Cycling Produces Graded Effects on Cognition and Microbiota Composition in Rats

Scope

The effects of diet cycling on cognition and fecal microbiota are not well understood.

Method and Results

Adult male Sprague-Dawley rats were cycled between a high-fat, high-sugar “cafeteria” diet (Caf) and regular chow. The impairment in place recognition memory produced by 16 days of Caf diet was reduced by switching to chow for 11 but not 4 days. Next, rats received 16 days of Caf diet in 2, 4, 8, or 16-day cycles, each separated by 4-day chow cycles. Place recognition memory declined from baseline in all groups and was impaired in the 16- versus 2-day group. Finally, rats received 24 days of Caf diet continuously or in 3-day cycles separated by 2- or 4-day chow cycles. Any Caf diet access impaired cognition and increased adiposity relative to controls, without altering hippocampal gene expression. Place recognition and adiposity were the strongest predictors of global microbiota composition. Overall, diets with higher Caf > chow ratios produced greater spatial memory impairments and larger shifts in gut microbiota species richness and beta diversity.

Conclusion

Results suggest that diet-induced cognitive deficits worsen in proportion to unhealthy diet exposure, and that shifting to a healthy chow for at least a week is required for recovery under the conditions tested here.     

Development of individual psychosocial competence in a high school setting.

The development of the competent self in adolescence, the interrelationship of psychotherapeutic and psychoeducational change, and the role of the high school counselor as a mental health gatekeeper were explored in a pre–post experimental–control design study of group counseling. 147 exemplary ("getting their lives together well and handling school well") and marginal ("having trouble getting their lives together and managing school") high school students participated. Precounseling assessments and patterns of change over the counseling period supported the 1st author's hierarchical competence configuration model of psychosocial functioning, consisting of self-attitudes, world-attitudes, and relevant behavioral attributes. Overall effectiveness of counseling was indicated at multiple levels by significant goal attainment (Kiresuk-Sherman Goal Attainment Scale) and by increased self-efficacy (Rotter's Internal–External Locus of Control Scale). The impact of counseling was significantly different for exemplary than for marginal students and for students from different race and sex subgroups. These findings confirm the interrelation of change patterns at behavioral and personality levels, the importance of sociocultural factors in individual psychosocial change patterns, and the potential therapeutic impact of relatively brief psychoeducational-psychotherapeutic interventions. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of visual pattern classification in preschool children: Prototypes and distinctive features.

Studied the use of prototypes and distinctive features in visual pattern classification with 12 Ss at each of 3 age levels: 4, 5, and 6 yrs. All Ss attended day-care centers in middle-class neighborhoods of metropolitan Canadian areas. Two tasks were performed: (a) an oddity task requiring selection of the odd pattern in problems containing 2 patterns generated from 1 prototype and 1 from another, and (b) a sequential task requiring designation from memory of each pattern's class membership. There was a marked improvement in oddity task classification accuracy between the 4- and 5-yr age levels. Performance at each age level could be predicted from measures of deviation from prototype and 2 distinctive features unrelated to pattern class membership. In the more difficult sequential task, the preschoolers did not respond to an entire set of features as subsumed in prototype measures, but a single class-defining feature significantly predicted the classifications of the 4- and 5-yr-olds. It is concluded that the ability to use single features develops prior to the ability to use a feature list or prototype and that both distinctive features and prototypes are important for perceptual learning and development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasound biometry in the diagnosis of amblyopia in keratoconus.

Here, we describe a case in which A-scan ultrasound biometry was used to differentially diagnose the cause of reduced vision in a patient with keratoconus. A patient with keratoconus presented with reduced visual acuity in one eye, not improvable above 6/18 with specialist keratoconus contact lens fitting. This monocular amblyopia was attributed to previous anisometropic ametropia by the use of ultrasound biometry. The report demonstrates the usefulness of ultrasound biometry in the detection of amblyopia in circumstances in which a previous assessment of amblyopia is not possible. This information will impact upon decisions made for the future clinical management in this case, especially if vision deteriorates so that a corneal graft is required.     

Delivery of nutrients and seston from the Muskegon River Watershed to near shore Lake Michigan

Drowned river mouth lakes are major features of coastal Great Lakes habitats and may influence nutrient and organic matter contributions from watersheds to near shore coastal zones. In May through October 2003, we measured loads of nutrients, surficial sediment, and seston to track the delivery of riverine-derived materials from the lower Muskegon River Watershed (MRW) into the near shore area of southeast Lake Michigan. Nutrient flux data indicated that seasonal loads of 1800 metric tons (MT) of particulate organic carbon, 3400 MT of dissolved organic carbon, and 24 MT of total phosphorus were discharged from the lower Muskegon River, with approximately 33% of TP load and 53% of the POC load intercepted within the drowned river mouth terminus, Muskegon Lake. Carbon: phosphorus molar ratios of seston in Muskegon River (C:P = 187) and Muskegon Lake (C:P = 176) were lower than in Lake Michigan (C:P = 334), indicating phosphorus limitation of phytoplankton in near shore Lake Michigan. Isotopic signatures of seston collected in Muskegon Lake were depleted in δ¹³C (− 30.8 ± 1.6‰) relative to the isotope signatures of seston from Lake Michigan (− 26.2 ± 1.3‰) or the mouth of the Muskegon River (− 28.1 ± 0.5‰), likely due to the presence of biogenic methane in Muskegon Lake. Seston δ¹⁵N increased on a strong east-to-west gradient within Muskegon Lake, indicating significant microbial processing of nutrients. The extent of nutrient uptake in Muskegon Lake altered the chemical and isotopic characterization of seston flowing into Lake Michigan from Muskegon River.