Looking Back: Cyclamate

The second in a series re-evaluating hazards identified in the 1950s and 60s

Formation and Evolution of Binary Asteroids

Satellites of asteroids have been discovered in nearly every known small body population, and a remarkable aspect of the known satellites is the diversity of their properties. They tell a story of vast differences in formation and evolution mechanisms that act as a function of size, distance from the Sun, and the properties of their nebular environment at the beginning of Solar System history and their dynamical environment over the next 4.5 Gyr. The mere existence of these systems provides a laboratory to study numerous types of physical processes acting on asteroids and their dynamics provide a valuable probe of their physical properties otherwise possible only with spacecraft. Advances in understanding the formation and evolution of binary systems have been assisted by: 1) the growing catalog of known systems, increasing from 33 to nearly 250 between the Merline et al. (2002) Asteroids III chapter and now, 2) the detailed study and long-term monitoring of individual systems such as 1999 KW4 and 1996 FG3, 3) the discovery of new binary system morphologies and triple systems, 4) and the discovery of unbound systems that appear to be end-states of binary dynamical evolutionary paths. Specifically for small bodies (diameter smaller than 10 km), these observations and discoveries have motivated theoretical work finding that thermal forces can efficiently drive the rotational disruption of small asteroids. Long-term monitoring has allowed studies to constrain the system's dynamical evolution by the combination of tides, thermal forces and rigid body physics. The outliers and split pairs have pushed the theoretical work to explore a wide range of evolutionary end-states.Comment: 42 pages, 4 figures, contribution to the Asteroids 4 boo

Stock assessment and management recommendations for Pacific sardine (Sardinops sagax) in 1997

The primary goal of sardine management as directed by the California Fish and Game Code is rehabilitation of the resource with an added objective of maximizing sustained harvest. Accordingly, the Code states that the annual sardine quota can be set at an amount greater than 1,000 tons, providing that the level of take allows for continued increase in the spawning population. We estimated the sardine population size to have been 464,000 short tons on July 1, 1997. Our estimate was based on output from a modified version of the integrated stock assessment model called CANSAR (Deriso et al. 1996). CANSAR is a forward-casting, age-structured analysis using fishery-dependent and fishery-independent data to obtain annual estimates of sardine abundance, year-class strength and age-specific fishing mortality for 1983 through the first semester of 1997. Non-linear least-squares criteria are used to find the best fit between model estimates and input data. Questions about stock structure and range extent remain major sources of uncertainty in assessing current sardine population biomass. Recent survey results and anecdotal evidence suggest increased sardine abundance in the Pacific Northwest and areas offshore from central and southern California. It is difficult to determine if those fish were part of the stock available to the California fishery. In an attempt to address this problem, the original CANSAR model was reconfigured into a Two-Area Migration Model (CANSAR-TAM) which accounted for sardine lost to the areas of the fishery and abundance surveys due to population expansion and net emigration. While the model includes guesses and major assumptions about net emigration and recruitment, it provides an estimate which is likely closer to biological reality than past assessments. The original CANSAR model was also used and estimates are provided for comparison. Based on the 1997 estimate of total biomass and the harvest formula used last year, we recommend a 1998 sardine harvest quota of 48,000 tons for the California fishery. The 1998 quota is a decrease of 11% from the final 1997 sardine harvest quota for California of 54,000 tons. (55pp.

Modeling Newborn Piglet Thermal Interactions with a Surface Energy Balance Model

A mathematical model was developed to describe the radiative and convective thermal interactions between a newborn piglet and it’s surroundings. The model incorporates surface energy balances for each surface in the enclosure. The model was verified with results from a simulated creep area and from published calorimetric studies on newborn pigs. Mathematical results were all within 5.5% of the measured results from a simulated creep-area. Compared with published studies, the mathematical model over-predicts heat loss in high-demand environments and under predicts heat loss in low-demand environments

Defining the Newborn Piglet’s Thermal Environment with an Effective Environmental Temperature

An effective environmental temperature (EET) developed for newborn piglets describes the thermal environment by incorporating the mean radiant temperature, dry-bulb temperature, and air velocity near the newborn. The adequacy of the defined EET was analyzed by comparing with three published studies on newborn sensible heat loss. Results from the published studies indicate that the EET predicted between 87% and 98% of the variability in the data

Status of the Pacific mackerel resource and fishery in 1998

Based on the projected Pacific mackerel biomass estimate of 132,500 tons for July 1, 1998, the commercial fishery quota for the 1998/99 fishing season was recommended and set at 33,700 short tons. The 1998 biomass was estimated using output from a stock assessment computer model called ADEPT and certain assumptions about fishing mortality during the first half of 1998. Several important changes were made to improve our assessment during 1998. The assessment model was changed from a quarterly to an annual one and now covers sixty-nine years of fishery data. New indices of relative abundance were added to the analysis to account for changes in mackerel biomass off central and northern California. The July 1, 1998, biomass estimate is slightly higher than last year's CDFG estimate of 101,000 tons for 1997. This year's results indicate there were more fish in the older year classes than previously estimated. (62pp.

Three-Dimensional Buoyant Turbulent Flows in a Scaled Model, Slot-Ventilated, Livestock Confinement Facility

A three-dimensional turbulence model was used to determine the effects of animal-generated buoyant forces on the airflow patterns and temperature and airspeed distributions in a ceiling-slot, ventilated, swine grower facility. The model incorporated the Lam-Bremhorst turbulence model for low-Reynolds Number airflow typical of slot-ventilated, livestock facilities. The predicted results from the model were compared with experimental results from a scaled-enclosure. The predicted and measured results indicated a rather strong cross-stream recirculation zone in the chamber that resulted in substantial three-dimensional temperature distributions for moderate to highly buoyancy-affected flows. Airflow patterns were adequately predicted for Arc \u3e 40 and J values \u3c 0.00053. For Arc \u3c 40 and J values \u3e 0.00053, the visualized patterns indicated that the jet separated from the ceiling before the opposing end-wall. This discrepancy was attributed to variations in the experimental and numerical inlet flow development assumptions

Poly(A)-Binding Protein Regulates the Efficiency of Translation Termination

Multiple factors influence translation termination efficiency, including nonsense codon identity and immediate context. To determine whether the relative position of a nonsense codon within an open reading frame (ORF) influences termination efficiency, we quantitate the production of prematurely terminated and/or readthrough polypeptides from 26 nonsense alleles of 3 genes expressed in yeast. The accumulation of premature termination products and the extent of readthrough for the respective premature termination codons (PTCs) manifest a marked dependence on PTC proximity to the mRNA 3\u27 end. Premature termination products increase in relative abundance, whereas readthrough efficiencies decrease progressively across different ORFs, and readthrough efficiencies for a PTC increase in response to 3\u27 UTR lengthening. These effects are eliminated and overall translation termination efficiency decreases considerably in cells harboring pab1 mutations. Our results support a critical role for poly(A)-binding protein in the regulation of translation termination and also suggest that inefficient termination is a trigger for nonsense-mediated mRNA decay (NMD)