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Range measurements made by satellite radar altimeters experience an electromagnetic (EM) bias toward the troughs of ocean waves. This EM bias was measured at the 13.6 GHz and 5.3 GHz operating frequencies of the NASA altimeter on the TOPEX/POSEIDON satellite in a series of 11 aircraft flights from January 17, 1991, through March 4, 1991, during the Surface WAve Dynamics Experiment (SWADE). The data are consistent with an earlier set of airborne measurements and indicate that EM bias is slightly higher at 5.3 GHz than at 13.6 GHz, and that the magnitudes of both biases increase with increasing wind speed, as does their difference. With some exceptions, EM bias shows little variation over a mesoscale region on a given day or within 1 or 2 h, but it can change significantly over a 6-h period. An examination of recent tower, airborne, and satellite measurements shows a consistency in the characteristics of the wind speed dependence but suggests that there may be a height dependence in the determinations, with the bias decreasing with increasing altitude. The airborne measurements appear to be the most reasonable basis for correcting the NASA altimeter range data from the TOPEX/POSEIDON satellite. In addition, a preliminary analysis of a very limited amount of the data acquired at 20.3 m s to the -1 in Southern Ocean Waves Experiment (SOWEX) has given confidence that the quadratic models for the prelaunch EM bias corrections are more appropriate for wind speed dependence than are the linear models initially considered.

Rotifers play important roles in freshwater communities. Despite their ubiquity, little is known about their evolutionary relationships. From an ecological perspective brachionid rotifers have received considerable attention yet the most basic feature of their phylogeny, the monophyly of the group, has not been investigated. We have sequenced both ITS regions from representatives of 5 genera and 23 species within Brachionidae in addition to species from families Epiphanidae, Lecanidae, and Euchlanidae. Both regions contained many informative sites and each data set contained a strong phylogenetic signal as indicated by g, values of -0.0755 (p [is less than] 0.01) and -0.6688 (p [is less than] 0.01) for ITS1 and ITS2, respectively. Data sets were analyzed individually and in combination using parsimony and maximum likelihood. Support for monophyly of the Brachionidae was found in all analyses. Monophyly of genera Keratella and Notholca were also supported. The position of Plationus patulus is investigated as is the placement of genus Rhinoglena.

Cyclical parthenogens combine the genetic benefits of sexual reproduction with the increased capacity of producing offspring asexually. The timing of sex within these populations can greatly influence future genetic variation. Rotifer populations in a series of ephemeral desert ponds were monitored daily following seasonal rains. Population sizes and reproductive status of individuals from a variety of species were determined in order to follow the allocation of reproductive resources to male (sexual) versus female (asexual) offspring through a population cycle. Levels of sexual reproduction ranged from 0 to 40% and varied between ponds. In very short-lived ponds, sexual reproduction was detected within 2 days of establishment of the rotifer population. In larger more persistent ponds, asexual reproduction was prevalent early in the population cycle with increasing sexual reproduction over time.

Evaluation of the extent to which intraspecific genetic variation provides an adaptive advantage for broadly distributed species requires data on intraspecific variation at both the genetic and phenotypic levels. We have previously reported that random DNA polymorphisms are more numerous in the robustly adapted American bullfrog (Rana catesbeiana) than in leopard frogs (Rana sp.) which it frequently displaces. To test whether greater variation in bullfrogs is also observed at a molecular phenotypic level, we have examined ganglioside patterns from brain tissues of both species. Gangliosides are heterogeneous glycolipids synthesized through a sequence of enzymatically catalyzed steps. Gangliosides were extracted, isolated, and resolved by 2D-TLC (Irwin & Schwarz. Comp Biochem Physiol 76B: 649, 1983). The intensity of individual bands was rank ordered for each specimen, and the correspondence of rank orders between specimens was assessed by Nei's (Am Nat 10:283, 1972) index of similarity. The intraspecific variability for ganglioside patterns was 27% greater, and the standard deviation was 40% greater, in bullfrogs than in leopard frogs. These results indicate that greater genetic variability in bullfrogs is seen at a molecular phenotypic as well as genotypic level. [Supported by NIH/RCMI Grant GR12RR08124 and NSF/RIMI Grant HRD-96285681.

Aquatic species inhabiting temporary habitats must complete their life cycle before environmental conditions preclude reproduction mid survival. In the case of monogonont rotifers, it is generally held that at least one generation of asexual (amictic) reproduction is necessary before diapausing eggs can be produced through sexual (mictic) reproduction. Here we present life history data for an undescribed Hexarthra species inhabiting shallow ponds in the Chihuahuan Desert which may dry up within days. This species deviates from the general life cycle pattern. From diapausing eggs in the sediments, up to 45.5% of females hatching are mictic and produce male offspring. This first generation of males can fertilize other first generation mictic females, thus diapausing eggs production can occur in a matter of days. In the lab, these females can produce fully developed diapausing eggs within 1.9d at 20[degrees]C and 1.2d at 30[degrees]C. In the ponds, females producing male offspring and diapausing eggs can be observed on the second and the third day, respectively, after ponds have filled with water. In very short-lived habitats, rapid production of new diapausing eggs may be crucial for the long-term survival of populations. In addition, embryonic development time (1.1d at 12[degrees]C, 0.5d at 20[degrees]C, and 0.3d at 30[degrees]C) and juvenile period (2.1 d at 12[degrees]C, 1.1d at 20[degrees]C, 0.5d at 30[degrees]C) are shorter than those of other rotifer species and may contribute to rapid population development and production of diapausing eggs.

A number of organizations banded together to develop two hard red winter-wheat germplasms known as KS92WGRC21 and KS92WGRC22. KS92WGRC21 was derived from the cross TAM200*3/TA 2570 while KS92WGRC22 was the result of the cross Century*3/TA 2567. The two were found to be high in resistance to wheat soilborne mosaic virus, wheat spindle-streak mosaic virus and powdery mildew. Although a genetic explanation for the non-susceptibility of the germplasms to the two viruses remains inexistent, there are findings that different loci are affecting the two viruses.

Abstract: In this paper, criteria for the prediction of a 3-D divergence of streamtubes within the entrance region of developing laminar flows between merging streams is presented. This divergence has a direct impact on the application of microscale flow cytometers based upon a 2-D design, as the exact downstream position of the sample population may not be accurately predictable. Also, the phenomenon could adversely affect the efficiency of fluidic sorting systems that have been incorporated into such devices. In this study a mini-scale flow cytometer with three streams merging at a single junction is analyzed to investigate the existence of any three-dimensional divergence of the inlet streams. This is achieved by visualizing dyed inlet streams from both isometric and planar views. A theory to predict this phenomenon is presented and validated using flow visualization and Particle Image Velocimetry (PIV). It is noted that the Reynolds numbers of the inlet streams are the only characterizing parameters for such a device under isothermal pressure driven flow conditions. A range of inlet flow ratios from 1 to 10 between the merging streams are examined. These flow ratio observations were carried out over a Reynolds number range of 23–53. The results show that a three-dimensional divergence of the inlet streams exists within the entrance region. The divergence was found to be almost non-existent at flow ratios of unity but becomes more apparent as the flow ratio is increased. It was also observed that the higher the magnitude of the Reynolds number, the more apparent the divergence became for each flow ratio investigated. Finally, the effect of this phenomenon on the development of microfluidic devices incorporating a similar geometry is discussed and conclusions are drawn. [Copyright &y& Elsevier]

We describe a 50-year-old Caucasian man with a family history of myoclonic epilepsy associated with ragged red fibers (MERRF) and a diagnosis of Human Immunodeficiency Virus (HIV). The patient had multiple risk factors for contracting HIV and was being followed in our clinic at the time of his diagnosis. Initial testing following seroconversion revealed a baseline CD4+ T-lymphocyte count of 652×106cells/l and a HIV-1 RNA of 14,781copies/ml. He reported exercise intolerance and had mild neurologic deficits, which worsened around the time of HIV seroconversion. These symptoms led to his subsequent diagnosis of MERRF by the detection of the A8344G point mutation in the tRNALys gene of mitochondrial DNA (mtDNA). The baseline estimated proportion of mutant genome was 39%. He showed a rapid course of HIV disease progression with a CD4+ T-lymphocyte nadir of 174×106cells/l associated with a HIV-1 RNA of 238,178copies/ml, within 17 months following HIV seroconversion. To avoid further mitochondrial insult, which could result from the use of a standard nucleoside reverse transcriptase inhibitor-containing regimen, a protease inhibitor regimen consisting of hard-gel saquinavir (Invirase™), and lopinavir/ritonavir (Kaletra™) was chosen for this patient. The patient''s CD4+ T-lymphocyte count increased to 282×106cells/l and his viral load became undetectable 7 months following the initiation of antiretroviral therapy. His neurologic symptoms did not worsen on this antiretroviral regimen. When initiating HIV therapy in individuals with metabolic myopathies related to mitochondrial dysfunction, it may be important to design an antiviral regimen that minimizes mitochondrial damage, yet effectively maintains durable viral suppression. [Copyright &y& Elsevier]