Misdiagnosis of omphalocele associated with Edwards syndrome and congenital heart disease

We present a case in which an apparent omphalocele, diagnosed at 30 weeks gestation ultrasound, led to identification of fetal trisomy 18 and congenital heart disease. At delivery, the fetus had the features of trisomy 18 and congenital heart disease but the omphalocele was absent. We suggest that the appearances seen are easily confused with a small omphalocele and could potentially result in unnecessary further investigations being performed.     

Sexual selection and spring arrival times of red-necked and Wilson's phalaropes

Summary Seasonal changes in sex ratios during a 4-year study of red-necked phalaropes and a 3-year study of Wilson's phalaropes showed that females preceded males to breeding and/or courtship areas. The degree to which females preceded males may have been constrained by harsh weather, as the arrival of red-necked phalaropes was synchronous in 1983, when spring was unusually late. Neither sex defended territories; females competed vigorously for direct access to males. These findings show that selection for sexually asynchronous arrival need not act through territoriality. We interpret early female arrival as an adaptation for obtaining mates and coclude that sexual selection may be an important determinant of arrival times in mate defense social systems.     

Temporal variability in winter travel patterns of Yellowstone bison: the effects of road grooming.

The influence of winter recreation on wildlife in Yellowstone National Park (YNP), Wyoming and Montana, USA, is a controversial issue. In particular, the effects of road grooming, done to facilitate snowmobile and snowcoach travel, on bison (Bison bison) ecology are under debate. We collected data during winters, from 1997 to 2005, on bison road use, off-road travel, and activity budgets to quantify temporal trends in the amount of bison road and off-road travel and to identify the ecological factors affecting bison movements and use of the groomed road system in the Madison-Gibbon-Firehole (MGF) area of YNP. Using model comparison techniques, we found bison travel patterns to be influenced by multiple, interacting effects. Road travel was negatively correlated with road grooming, and we found no evidence that bison preferentially used groomed roads during winter. Snow water equivalent, bison density, and the springtime melt period were positively correlated with both bison road and off-road travel. From behavioral scans on 68,791 bison, we found that travel is only a small percentage (11%) of all bison activity, with foraging comprising 67% of observations. Also, only 7% of traveling bison and 30% of foraging bison were displacing snow, and we suggest foraging, rather than traveling, is likely the major energetic cost to bison in winter. Bison utilize their own trail network, connecting foraging areas using stream corridors, geothermal pathways, and self-groomed travel routes. Our results indicate that temporal patterns in bison road travel are a manifestation of general travel behavior and that groomed roads in the MGF do not appear to be a major factor influencing bison ecology and spatial redistribution. We suggest that the changes in bison spatial dynamics during the past three decades have likely been the result of the natural phenomenon of density-dependent range expansion, rather than having been caused by the anthropogenic influence of road grooming.     

Directions in Conservation Biology: Comments on Caughley

The recent review by Caughley (1994) on approaches used in conservation biology suggested that there are two: the small population paradigm and the declining population paradigm. We believe that this division is overly simplistic and that it should not be perpetuated. Both the deterministic factors that reduce population size and the stochastic factors that lead to the final extinction of a small population are critical to consider in preventing extinction. Only through an overall and comprehensive effort, which we call inclusive population viability analysis, can extinction processes be understood and mitigated. In this context we discuss Caughley's comments about genetics, demography, and general population viability, with particular attention to cheetahs (Acinonyx jubatus) and Pacific salmon (Oncorhynchus sp. ) .     

Toward a high-rate enhanced biological phosphorus removal process in a membrane-assisted bioreactor.

A membrane enhanced biological phosphorus removal (MEBPR) process was studied to determine the impact of hydraulic retention time (HRT) and solids retention time (SRT) on the removal of chemical oxygen demand (COD), nitrogen, and phosphorus from municipal wastewater. The MEBPR process was capable of delivering complete nitrification independent of the prevailing operating conditions, whereas a significant improvement in COD removal efficiency was observed at longer SRTs. In the absence of carbon-limiting conditions, the MEBPR process was able to achieve low phosphorus concentrations in the effluent at increasingly higher hydraulic loads, with the lowest HRT being 5 hours. The MEBPR process was also able to maintain optimal phosphorus removal when the SRT was increased from 12 to 20 days. However, at higher suspended solids concentrations, a substantial increase was observed in carbon utilization per unit mass of phosphorus removed from the influent. These results offer critical insights to the application of membrane technology for biological nutrient removal systems.     

A closer look at detectability

Environmental and Ecological Statistics - The theory underlying line transect and variable circular plot surveys—distance sampling—begins with an assumed detectability function, giving...     

Tail size and female choice in the guppy (Poecilia reticulata)

Summary Under laboratory conditions, female guppies demonstrate a clear preference for males with larger tails, and this preference translates into enhanced reproductive fitness for these males. Females also prefer males with higher display rates, a behavior which appears to be linked to tail size, but which can be experimentally disassociated. This appears to be a case of female-choice sexual selection.     

Reclamation techniques in southwestern wyoming

Bridger Coal Company operates a 5.8 million tpy surface coal mine thrity five miles northeast of Rock Springs. Wyoming. Approximately 20.000 acres are under permit, with disturbance over the life of the mine projected to reach 10,000 acres. Located on the western rim of the continental divide, the mine receives less than 8.5 inches of precipitation annually. Soils in the area are coarse-textured. and problems associated with elevated salinity and sodicity arc encountered. A variety of common reclamation techniques have been modified to reflect these conditions. Soil horizons are segregated during salvage operations (the surface six inches as topsoil and the balance as subsoil). Unsuitable materials are not salvaged. Direct application of soil is used (over 130 acres in 1983) to maximize native plant regeneration and conserve soil fertility. Inter-seeding of seeding failures has proven to be significantly more successful than chisel plowing and reseeding. Broadcast seeding has been ineffective because of strong winds, and a no till drill has been modified to handle diverse seed mixes and rock conditions. The utility of fertilization under typically xeric moisture regimes is being evaluated. A research project has been initiated to assess establishment of a predominately native, diverse seed mix under irrigation, as well as to determine irrigation rates and duration.     

Conditional and unconditional estimators of population size

Estimators for the population sizes of animal species are similar to Horvitz-Thompson estimators — they involve dividing counts of detected animals by the probabilities of detection. Knowing detection probabilities for different subpopulations allows one to estimate each sub-population size with such an estimator, and to add the results for an estimator of the total population. In the case where the proportions of animals belonging to the different sub-populations are also known, this paper shows that using those proportions to arrive at a common average detection probability will, when used in conjunction with the total number of animals detected, result in a better estimator. We provide two examples where the inferior estimator may seem sensible.