Branching frequency of Thalassia testudinum (Banks ex K?nig) as an ecological indicator in Florida Bay

The effects of short-shoot density and light availability on rhizome apical meristem density and rhizome branch frequency of Thalassia testudinum were assessed in ten basins in Florida Bay. Core samples for density measurements were obtained from 27-30 stations per basin (over 300 sampling stations total) during the spring 1998 and spring 1999 sampling of the Fish Habitat Assessment Program (FHAP). Rhizome branch frequency (apicals short-shoots-1) was calculated from the core data. Light attenuation, (Kd), estimated from in situ measurements of secchi depths, light profiles of scalar irradiance and Kd values calculated from AVHRR satellite imagery using GIS indicated high light availability and similar optical water quality between the two years. Light attenuation estimates were coupled with USGS bathymetry to determine if there was a significant interaction between light availability and Thalassia densities or rhizome branching. Apical density and short-shoot density were linearly correlated in Florida Bay. Neither apical density nor rhizome branch frequency in 1998 was found to be a good predictor of short-shoot density fluctuations between the spring of 1998 and 1999. Increases in rhizome branch frequencies were only weakly associated with between-year increases in short-shoot densities in this study. Mean rhizome branch frequencies were 0.19 + 0.02, and 0.15 + 0.01, for spring 1998 and spring 1999, respectively. The relatively lower rhizome branching rates observed in Florida Bay in 1998 and 1999 may reflect a density-dependent inhibitory response due to the increase in short-shoot densities following the seagrass die-off from 1990 to 1998 (305 short shoots/m2 in 1990, Durako 1995 versus 590 & 602 short shoots/m2 in this study). There was a positive relationship between percent surface irradiance and short-shoot density. In conclusion, rhizome branch frequency was not a good ecoindicator of light availability or short-shoot density changes in Florida Bay. In contrast, it appears that the effect of short-shoot density, which did respond positively to increasing light availability, may be more important in effecting rhizome branching. Therefore, rhizome branch frequency may be a biological indicator that responds to short-shoot density changes in this non-light limited Bay

Angiogenesis gene expression in murine endothelial cells during post-pneumonectomy lung growth

Although blood vessel growth occurs readily in the systemic bronchial circulation, angiogenesis in the pulmonary circulation is rare. Compensatory lung growth after pneumonectomy is an experimental model with presumed alveolar capillary angiogenesis. To investigate the genes participating in murine neoalveolarization, we studied the expression of angiogenesis genes in lung endothelial cells. After left pneumonectomy, the remaining right lung was examined on days 3, 6, 14 and 21days after surgery and compared to both no surgery and sham thoracotomy controls. The lungs were enzymatically digested and CD31+ endothelial cells were isolated using flow cytometry cell sorting. The transcriptional profile of the CD31+ endothelial cells was assessed using quantitative real-time polymerase chain reaction (PCR) arrays. Focusing on 84 angiogenesis-associated genes, we identified 22 genes with greater than 4-fold regulation and significantly enhanced transcription (p <.05) within 21 days of pneumonectomy. Cluster analysis of the 22 genes indicated that changes in gene expression did not occur in a single phase, but in at least four waves of gene expression: a wave demonstrating decreased gene expression more than 3 days after pneumonectomy and 3 sequential waves of increased expression on days 6, 14, and 21 after pneumonectomy. These findings indicate that a network of gene interactions contributes to angiogenesis during compensatory lung growth

Thermal Transport in Micro- and Nanoscale Systems

Small-scale (micro-/nanoscale) heat transfer has broad and exciting range of applications. Heat transfer at small scale quite naturally is influenced – sometimes dramatically – with high surface area-to-volume ratios. This in effect means that heat transfer in small-scale devices and systems is influenced by surface treatment and surface morphology. Importantly, interfacial dynamic effects are at least non-negligible, and there is a strong potential to engineer the performance of such devices using the progress in micro- and nanomanufacturing technologies. With this motivation, the emphasis here is on heat conduction and convection. The chapter starts with a broad introduction to Boltzmann transport equation which captures the physics of small-scale heat transport, while also outlining the differences between small-scale transport and classical macroscale heat transport. Among applications, examples are thermoelectric and thermal interface materials where micro- and nanofabrication have led to impressive figure of merits and thermal management performance. Basic of phonon transport and its manipulation through nanostructuring materials are discussed in detail. Small-scale single-phase convection and the crucial role it has played in developing the thermal management solutions for the next generation of electronics and energy-harvesting devices are discussed as the next topic. Features of microcooling platforms and physics of optimized thermal transport using microchannel manifold heat sinks are discussed in detail along with a discussion of how such systems also facilitate use of low-grade, waste heat from data centers and photovoltaic modules. Phase change process and their control using surface micro-/nanostructure are discussed next. Among the feature considered, the first are microscale heat pipes where capillary effects play an important role. Next the role of nanostructures in controlling nucleation and mobility of the discrete phase in two-phase processes, such as boiling, condensation, and icing is explained in great detail. Special emphasis is placed on the limitations of current surface and device manufacture technologies while also outlining the potential ways to overcome them. Lastly, the chapter is concluded with a summary and perspective on future trends and, more importantly, the opportunities for new research and applications in this exciting field