Determinants of household choice of breakfast cereals: healthy or unhealthy?

We studied consumer demand for more and less healthy breakfast cereals. Using ACNielsen Homescan database and USDA food nutrition data, we developed three cereal nutrition indexes for each household in the data. In addition to the standard demographic characteristics of households and prices, we included variables representing differences between private labels and national brands. We found that the structure of the industry, through its effect on the product mix produced, affects consumer choice of nutritious foods. Some households buy fewer healthy cereals simply through reluctance to trust private labels. Among all factors expected to influence consumer purchases, the prices appear to have the strongest effect on the healthiness of the choice of breakfast cereals, which is a relatively inexpensive product. Households with children and teens buy less healthy cereals, while older and more educated households make healthier choices.consumer demand, healthy and unhealthy food, breakfast cereals, Consumer/Household Economics,

IMPLICATION OF RECENT USER CHARGE LEGISLATION FOR BARGE TRANSPORTATION OF AGRICULTURAL COMMODITIES

Political Economy,

PORT ELEVATOR CAPACITY AND NATIONAL AND WORLD GRAIN SHIPMENTS

An analysis is conducted on the port component of the United States grain export system. A transshipment model is utilized which covers both United States internal and foreign shipments of corn, soybeans, and wheat during the four quarters of a year. The model suggests that there will be quarter to quarter constraints on port capacity but that annual capacity is adequate. Through sensitivity analysis a number of key factors were found which influence the adequacy of the current port system. Port adequacy is found to depend not as much on export market location as it does on domestic transportation rates and policies.International Relations/Trade,

MODELING AND ANALYSIS OF TURBOJET COMPRESSOR INLET TEMPERATURE MEASUREMENT SYSTEM PERFORMANCE

Accurate measurement of turbine engine compressor inlet total temperature is paramount for controlling engine speed and pressure ratio. Various methods exist for measuring compressor inlet total temperature on turbojet engines with hydromechanical control. One method involves the use of an ejector-diffuser system (eductor) to pull air from the engine inlet in order to measure the incoming total temperature. Analysis of historical test data has revealed that the inlet temperature measurement can be biased at certain flight conditions causing engine mis-scheduling and off-nominal engine operation. This bias is characterized primarily by adverse heat transfer effects and secondly by poor flow quality in the eductor tubing. Alternate eductor system configurations have been proposed to mitigate temperature bias. A one-dimensional engineering model of the eductor system was developed to facilitate the analysis of baseline and alternate eductor configurations. The model is calibrated with results from Computational Fluid Dynamics and validated with ground test data. The validated model is used to quantify the performance of several eductor configurations throughout the range of expected operating conditions and to quantify the amount of compressor inlet temperature measurement bias mitigation each configuration provides

FUNDAMENTAL STUDY AND DEVELOPMENT OF TUNED ACTIVE FLOW CONTROL ACTUATORS

A novel, multi-level, flow-control actuator was developed using piezoceramic materials. Several actuators were fabricated in various shapes and sizes to produce a variety of effects for flow control applications. The actuators were studied in a quiescent-air bench test to understand the vibrations produced by various actuator shapes. The actuator flow-control effect was studied experimentally with flat-plate and cavity configurations, and was studied numerically using moving boundary conditions and dynamic meshing. The disturbances produced by the actuator couple with the cavity flow field producing increased cavity tones, increased vorticity, and sustainment of large-scale vorticity downstream of the cavity. The combined actuation result, from perturbations upstream of the cavity to increased vorticity downstream of the cavity, is the novel multi-level actuator developed and studied in this research. The largest actuator was experimentally tested in boundary layers with free-stream Mach numbers from 0.1 to 0.5 and Reynolds numbers, based on momentum thickness, from approximately 800 to 3600. Actuator effects were measured using high-frequency-response pressure instrumentation in the floor downstream of the actuator. The actuator produced disturbances with amplitudes at least 30 dB above the noise floor and frequencies nine-times the actuator driving frequency. The disturbances created by the actuator coupled with the boundary layer flow and were observable up to 62 kHz. A time-dependent effect from changing actuation frequency was observed on the stability of the flow. A compact, multi-actuator pack was designed to study multi-level flow control using experimental tests of a two-dimensional cavity flow at Mach numbers of 0.1, 0.2, and 0.3. Actuator operation did not produce amplified cavity oscillations at all Rossiter tones in the experiments. However, significant flow coupling occurred when the actuator driving frequency matched a Rossiter tone and a fundamental cavity acoustic tone. The cavity amplifications were stronger when the distance between the actuator and the cavity leading edge was increased. The numerical simulations showed that the actuator produced cavity flow amplifications at the first Rossiter tone about 8 dB higher amplitude than without actuation

Effects of quantized fields on the spacetime geometries of static spherically symmetric black holes

Analytic approximations for the stress-energy of quantized fields in the Hartle-Hawking state in static black hole spacetimes predict divergences on the event horizon of the black hole for a number of important cases. Such divergences, if real, could substantially alter the spacetime geometry near the event horizon, possibly preventing the black hole from existing. The results of three investigations of these types of effects are presented. The first involves a new analytic approximation for conformally invariant fields in Reissner-Nordstrom spacetimes which is finite on the horizon. The second focuses on the stress-energy of massless scalar fields in Schwarzschild-de Sitter black holes. The third focuses on the stress-energy of massless scalar fields in zero temperature black hole geometries that could be solutions to the semiclassical backreaction equations near the event horizon of the black hole.Comment: 5 pages. To appear in the "Proceedings of the Eleventh Marcel Grossmann Meeting on General Relativity", July 2006, Berlin, German

Real Food Lunch and the Student Food Cooperative

Slides from 5-minute IGNITE sessio

Spatial and Temporal Dynamics of Habitat Selection Across Canopy Gradients Generates Patterns of Species Richness and Composition in Aquatic Beetles

1. Colonisation is a critical ecological process influencing both population and community level dynamics by connecting spatially discrete habitat patches. How communities respond to both natural and anthropogenic disturbances, furthermore, requires a basic understanding of how any environmental change modifies colonisation rates. For example, disturbance-induced shifts in the quantity of forest cover surrounding aquatic habitats have been associated with the distribution and abundance of numerous aquatic taxa. However, the mechanisms generating these broad and repeatable field patterns are unclear. 2. Such patterns of diversity could result from differential spatial mortality post colonisation, or from colonisation alone if species select sites non-randomly along canopy coverage gradients. We examined the colonisation/oviposition dynamics of aquatic beetles in experimental ponds placed under both open and closed forest canopies. 3. Canopy coverage imposed a substantial behavioural filter on the colonisation and reproduction of aquatic beetles representing multiple trophic levels, and resulted in significantly higher abundance, richness, and oviposition activity in open canopy ponds. These patterns strengthened overtime; although early in the experiment, the most abundant beetle had similar abundance in open and closed ponds. However, its abundance subsequently declined and then most other species heavily colonised open canopy ponds. 4. The primary response of many aquatic species to disturbances that generate canopy coverage gradients surrounding aquatic ecosystems is behavioural. The magnitude of the colonisation responses reported here rivals, if not exceeds, those produced by predators, suggesting that aquatic landscapes are behaviourally assessed and partitioned across multiple environmental gradients. The community level structure produced solely by selective colonisation, is predicted to strongly modify how patch area and isolation affect colonisation rates and the degree to which communities are linked by the flux of individuals and species

Effect of Level of Farm Mechanization Early in Life on Bone Later in Life

OBJECTIVE: To determine whether an active rural lifestyle during childhood and adolescence, defined as low farm mechanization, was associated with bone measures later in life.METHODS: DXA bone data from total body, hip and spine, and pQCT data from 4% and 20% distal radius were obtained on 330 individuals (157 women) aged 20-66 years who farmed at least 75% of their lives. Primary bone outcomes included areal bone mineral density (aBMD), aBMD Z-scores, cortical and trabecular volumetric BMD, cortical thickness and periosteal circumference. Relationship between bone and recall of level of farm mechanization as a child was determined after stratifying by sex and controlling for covariates.RESULTS: Controlling for covariates, females from low mechanized farms had higher femoral neck (FN) bone area (p=0.03) than those on high or moderate mechanized farms. No group differences in pQCT ulna measurements or z-scores were found in either gender.CONCLUSION: A low farm mechanization level (high physical activity) prior to 20 years of age is associated with greater FN bone area in females. Future research that includes type and amount of physical activity performed will contribute to growing knowledge of how and when regular physical activity during childhood and adolescence affects adult bone health

Greater Polar Moment of Inertia at the Tibia in Athletes Who Develop Stress Fractures

Background: Several previous investigations have determined potential risk factors for stress fractures in athletes and military personnel. Purpose: To determine factors associated with the development of stress fractures in female athletes. Study Design: Case-control study; Level of evidence, 3. Methods: A total of 88 female athletes (cross-country, n ¼ 29; soccer, n ¼ 15; swimming, n ¼ 9; track and field, n ¼ 14; volleyball, n ¼ 12; and basketball, n ¼ 9) aged 18 to 24 years were recruited to participate in a longitudinal bone study and had their left distal tibia at the 4%, 20%, and 66% sites scanned by peripheral quantitative computed tomography (pQCT). Patients included 23 athletes who developed stress fractures during the following year (cases). Whole body, hip, and spine scans were obtained using dual-energy x-ray absorptiometry (DXA). Analysis of covariance was used to determine differences in bone parameters between cases and controls after adjusting for height, lower leg length, lean mass, fat mass, and sport. Results: No differences were observed between cases and controls in any of the DXA measurements. Cases had significantly greater unadjusted trabecular bone mineral content (BMC), greater polar moment of inertia (PMI) at the 20% site, and greater cortical BMC at the 66% site; however, after adjusting for covariates, the differences became nonsignificant. When analyses were repeated using all individuals who had ever had a stress fracture as cases (n ¼ 31) and after controlling for covariates, periosteal circumference was greater in the cases than the controls (71.1 ± 0.7 vs 69.4 ± 0.5 mm, respectively; P ¼ .04). Conclusion: A history of stress fractures is associated with larger bones. These findings are important because larger bones were previously reported to be protective against fractures and stress fractures, but study findings indicate that may not always be true. One explanation could be that individuals who sustain stress fractures have greater loading that results in greater periosteal circumference but also results in the development of stress fractures