Development and testing of the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS) cm and mm wavelength occultation instrument

We present initial results from testing a new remote sensing system called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). ATOMMS is designed as a satellite-to-satellite occultation system for monitoring climate. We are developing the prototype instrument for an aircraft to aircraft occultation demonstration. Here we focus on field testing of the ATOMMS instrument, in particular the remote sensing of water by measuring the attenuation caused by the 22 GHz and 183 GHz water absorption lines. Our measurements of the 183 GHz line spectrum along an 820 m path revealed that the AM 6.2 spectroscopic model provdes a much better match to the observed spectrum than the MPM93 model. These comparisons also indicate that errors in the ATOMMS amplitude measurements are about 0.3%. Pressure sensitivity bodes well for ATOMMS as a climate instrument. Comparisons with a hygrometer revealed consistency at the 0.05 mb level, which is about 1% of the absolute humidity. Initial measurements of absorption by the 22 GHz line made along a 5.4 km path between two mountaintops captured a large increase in water vapor similar to that measured by several nearby hygrometers. A storm passage between the two instruments yielded our first measurements of extinction by rain and cloud droplets. Comparisons of ATOMMS 1.5 mm opacity measurements with measured visible opacity and backscatter from a weather radar revealed features simultaneously evident in all three datasets confirming the ATOMMS measurements. The combined ATOMMS, radar and visible information revealed the evolution of rain and cloud amounts along the signal path during the passage of the storm. The derived average cloud water content reached typical continental cloud amounts. These results demonstrated a significant portion of the information content of ATOMMS and its ability to penetrate through clouds and rain which is critical to its all-weather, climate monitoring capability

Monorail/Foxa2 regulates floorplate differentiation and specification of oligodendrocytes, serotonergic raphe neurones and cranial motoneurones

In this study, we elucidate the roles of the winged-helix transcription factor Foxa2 in ventral CNS development in zebrafish. Through cloning of monorail (mol), which we find encodes the transcription factor Foxa2, and phenotypic analysis of mol(-/-) embryos, we show that floorplate is induced in the absence of Foxa2 function but fails to further differentiate. In mol(-/-) mutants, expression of Foxa and Hh family genes is not maintained in floorplate cells and lateral expansion of the floorplate fails to occur. Our results suggest that this is due to defects both in the regulation of Hh activity in medial floorplate cells as well as cell-autonomous requirements for Foxa2 in the prospective laterally positioned floorplate cells themselves. Foxa2 is also required for induction and/or patterning of several distinct cell types in the ventral CNS. Serotonergic neurones of the raphe nucleus and the trochlear motor nucleus are absent in mol(-/-) embryos, and oculomotor and facial motoneurones ectopically occupy ventral CNS midline positions in the midbrain and hindbrain. There is also a severe reduction of prospective oligodendrocytes in the midbrain and hindbrain. Finally, in the absence of Foxa2, at least two likely Hh pathway target genes are ectopically expressed in more dorsal regions of the midbrain and hindbrain ventricular neuroepithelium, raising the possibility that Foxa2 activity may normally be required to limit the range of action of secreted Hh proteins

Rapid Mapping of Zebrafish Mutations With SNPs and Oligonucleotide Microarrays

Large-scale genetic screens in zebrafish have identified thousands of mutations in hundreds of essential genes. The genetic mapping of these mutations is necessary to link DNA sequences to the gene functions defined by mutant phenotypes.Here, we report two advances that will accelerate the mapping of zebrafish mutations: (1) The construction of a first generation single nucleotide polymorphism (SNP) map of the zebrafish genome comprising 2035 SNPs and 178 small insertions/deletions, and (2) the development of a method for mapping mutations in which hundreds of SNPs can be scored in parallel with an oligonucleotide microarray.We have demonstrated the utility of the microarray technique in crosses with haploid and diploid embryos by mapping two known mutations to their previously identified locations.We have also used this approach to localize four previously unmapped mutations.We expect that mapping with SNPs and oligonucleotide microarrays will accelerate the molecular analysis of zebrafish mutations

Saturated Lipid Sources in Feeds for Sunshine Bass: Alterations in Production Performance and Tissue Fatty Acid Composition

Feeds rich in saturated (SFAs) and monounsaturated fatty acids (MUFA) appear to maximize the retention of long-chain polyunsaturated fatty acids (LC-PUFA) in the fillets of sunshine bass (female white bass Morone chrysops × male striped bass M. saxatilis). To determine whether different sources of SFA and MUFA have equivalent effects on tissue fatty acid (FA) profile change, coconut (CO) and palm oils(PO) were evaluated as partial and complete substitutes for fish oil (FO) in feeds for juvenile sunshine bass. After 8 weeks of culture, the production performance of all groups was within the acceptable range for sunshine bass; however, weight gain was significantly reduced within the 100%-CO group. Partial replacement of FO with CO or PO resulted in significant alteration of fillet FA profiles, and these changes were exacerbated in the complete-FO-replacement groups. The LC-PUFA were disproportionately enriched in the fillets of fish fed the reduced or FO-free feeds, whereas dietary surpluses of 12:0 and 14:0 (CO-based feeds) and 16:0 (PO-based feeds) were not reflected in any of the tissues analyzed. Rather, the levels of the SFA elongation–desaturation products (i.e., 18:0 and 18:1[n-9]) were elevated, particularly within liver lipid, suggesting enhanced FA biotransformation activity among fish fed higher levels of either alternative lipid source. Based on tissue FA composition, PO and CO appear to be approximately equivalent in terms of fillet LC-PUFA retention. However, the digestibility and utilization of these feedstuffs must be further investigated to maximize the ability of PO and CO to (partially or completely) replace FO in sunshine bass feeds

Electrochemical Formation of Germanene: pH 4.5

Germanene is a single layer allotrope of Ge, with a honeycomb structure similar to graphene. This report concerns the electrochemical formation of germanene in a pH 4.5 solution. The studies were performed using in situ Electrochemical Scanning Tunneling Microscopy (EC-STM), voltammetry, coulometry, surface X-ray diffraction (SXRD) and Raman spectroscopy to study germanene electrodeposition on Au(111) terraces. The deposition of Ge is kinetically slow and stops after 2–3 monolayers. EC-STM revealed a honeycomb (HC) structure with a rhombic unit cell, 0.44 ± 0.02 nm on a side, very close to that predicted for germanene in the literature. Ideally the HC structure is a continuous sheet, with six Ge atoms around each hole. However, only small domains, surrounded by defects, of this structure were observed in this study. The small coherence length and multiple rotations domains made direct observation with surface X-ray diffraction difficult. Raman spectroscopy was used to investigate the multi-layer Ge deposits. A peak near 290 cm^(−1), predicted to correspond to germanene, was observed on one particular area of the sample, while the rest resembled amorphous germanium. Electrochemical studies of germanene showed limited stability when exposed to oxygen

Plasma Magnetohydrodynamics and Energy Conversion

Contains reports on five research projects.U. S. Air Force (Research and Technology Division) under Contract AF33(615)-1083 with the Air Force Aero Propulsion Laboratory, Wright-Patterson Air Force Base, Ohi

Antagonism between Gdf6a and retinoic acid pathways controls timing of retinal neurogenesis and growth of the eye in zebrafish.

Maintaining neurogenesis in growing tissues requires a tight balance between progenitor cell proliferation and differentiation. In the zebrafish retina, neuronal differentiation proceeds in two stages with embryonic retinal progenitor cells (RPCs) of the central retina accounting for the first rounds of differentiation, and stem cells from the ciliary marginal zone (CMZ) being responsible for late neurogenesis and growth of the eye. In this study, we analyse two mutants with small eyes that display defects during both early and late phases of retinal neurogenesis. These mutants carry lesions in gdf6a, a gene encoding a BMP family member previously implicated in dorsoventral patterning of the eye. We show that gdf6a mutant eyes exhibit expanded retinoic acid (RA) signalling and demonstrate that exogenous activation of this pathway in wild-type eyes inhibits retinal growth, generating small eyes with a reduced CMZ and fewer proliferating progenitors, similar to gdf6a mutants. We provide evidence that RA regulates the timing of RPC differentiation by promoting cell cycle exit. Furthermore, reducing RA signalling in gdf6a mutants re-establishes appropriate timing of embryonic retinal neurogenesis and restores putative stem and progenitor cell populations in the CMZ. Together, our results support a model in which dorsally expressed gdf6a limits RA pathway activity to control the transition from proliferation to differentiation in the growing eye