Characterization of Metastatic Tumor Formation by the Colony Size Distribution

Knowledge regarding the kinetics of metastatic tumor formation, as related to the growth of the primary tumor, represents a fundamental issue in cancer biology. Using an in vivo mammalian model, we show here that one can obtain useful information from the frequency distribution of the sizes of metastatic colonies in distant organs after serial sectioning and image reconstruction. To explain the experimental findings, we constructed a biophysical model based on the respective growth patterns of the primary tumor and metastases and a stochastic process of metastatic colony formation. Heterogeneous distributions of various biological parameters were considered. We found that the elementary assumption of exponential forms of growth for the primary tumor and metastatic colonies predicts a linear relation on a log-log plot of a metastatic colony size distribution, which was consistent with the experimental results. Furthermore, the slope of the curve signifies the ratio of growth rates of the primary and the metastases. Non-exponential (Gompertzian and logistic) tumor growth patterns were also incorporated into the theory to explain possible deviation from the log-log linear relation. The observed metastasis-free probability also supported the assumption of a time-dependent Poisson process. With this approach, we determined the mechanistic parameters governing the process of metastatogenesis in the lungs for two murine tumor cell lines (KHT and MCaK). Since biological parameters specified in the model could be obtained in the laboratory, a workable metastatic "assay" may be established for various malignancies and in turn contribute in formulating rational treatment regimens for subclinical metastases.Comment: 14 pages, 6 figure

Evolutionary Model of e-Procurement Adoption: A Case of the Vietnam Construction Industry

In order to propose more effective solutions to improve the diffusion of e-procurement technologies in the construction sector, it is very important to get a better understanding on the practical evolutionary process of e-procurement adoption at the enterprise level. This cases-study seeks to investigate the strategic evolution of e-procurement adoption in construction companies. Data collected from in-depth semi-structured interviews was analyzed by within-case and cross-case analyses to understand well the similarities and differences between the company cases regarding the way e-procurement technologies have been adopting and implementing. The present study found out a six-stage evolutionary model of e-procurement implementation specific for the context of Vietnamese construction industry. Further, it also proposed the best practical solutions for the cases studied as well as for the general context toward more collaborative e-procurement environment. Although this study is based on the experience of the construction section in a specific country, it is believed its results may be applicable to other developing countries. Using the evolutionary model developed, construction companies are able to self-assess and locate their e-procurement adoption level, and so that establish appropriate practical solutions to move forward a higher level of e-procurement applicability

A Search for Variable Stars and Planetary Occultations in NGC2301 I: Techniques

We observed the young open cluster NGC 2301 for 14 nights in Feb. 2004 using the orthogonal transfer CCD camera (OPTIC). We used PSF shaping techniques ("square stars") during the observations allowing a larger dynamic range (4.5 magnitudes) of high photometric precision results ($\le$2 mmag) to be obtained. These results are better than similar observing campaigns using standard CCD imagers. This paper discusses our observational techniques and presents initial results for the variability statistics found in NGC 2301. Details of the variability statistics as functions of color, variability type, stellar type, and cluster location will appear in paper II

Seizing the Moment: Realizing the Promise of Student-Centered Learning

This brief outlines policy recommendations for supporting student-centered learning at the local, state, and federal level

Analog VLSI system for active drag reduction

We describe an analog CMOS VLSI system that can process real-time signals from surface-mounted shear stress sensors to detect regions of high shear stress along a surface in an airflow. The outputs of the CMOS circuit are used to actuate micromachined flaps with the goal of reducing this high shear stress on the surface and thereby lowering the total drag. We have designed, fabricated, and tested parts of this system in a wind tunnel in laminar and turbulent flow regimes

A wafer-scale MEMS and analog VLSI system for active drag reduction

We describe an analog CMOS VLSI system that can process real-time signals from integrated shear stress sensors to detect regions of high shear stress along a surface in an airflow. The outputs of the CMOS circuit control the actuation of integrated micromachined flaps with the goal of reducing this high shear stress on the surface and thereby lowering the total drag. We have designed, fabricated, and tested components of this system in a wind tunnel in both laminar and turbulent flow regimes with the goal of building a wafer-scale system

Individual, sexual and temporal variation in the winter home range sizes of GPS-tagged Eurasian Curlews Numenius arquata

Capsule: Eurasian Curlews Numenius arquata were faithful to foraging and roosting areas on their coastal wintering grounds, including a habitat creation site. Home range sizes were greater at night than during the day, and showed high inter-individual variability which was not related to sex. Aims: To examine factors affecting variation in the winter home range size of the largest European wader species: the near-threatened Eurasian Curlew Numenius arquata. Methods: We examined individual, sexual and temporal (day/night, seasonal and annual) variation in the size of the home ranges of 18 GPS tagged Curlews captured at two sites on the Humber Estuary, UK. Results: Home ranges were small (mean ± SD = 555.5 ± 557.9 ha) and varied slightly in size through the non-breeding season (September–March). We found some annual differences in home range size, and there was some evidence that home range size was greater at night compared to daytime. There was strong inter-individual variation in home range size, which was not related to the species’ sexual size dimorphism and thus potential differences in resource use. Conclusions: Our results highlight that wintering Curlews on the Humber Estuary maintain small home ranges which vary strongly between individuals. Knowledge of the home range size of wintering waders is vital to inform management responses to the potential impacts of environmental changes such as sea-level rise and improving the efficacy of compensatory habitats

A surface-micromachined shear stress imager

A new MEMS shear stress sensor imager has been developed and its capability of imaging surface shear stress distribution has been demonstrated. The imager consists of multi-rows of vacuum-insulated shear stress sensors with a 300 /spl mu/m pitch. This small spacing allows it to detect surface flow patterns that could not be directly measured before. The high frequency response (30 kHz) of the sensor under constant temperature bias mode also allows it to be used in high Reynolds number turbulent flow studies. The measurement results in a fully developed turbulent flow agree well with the numerical and experimental results previously published

Feral swine damage to globally imperiled wetland plant communities in a significant biodiversity hotspot in Florida

We studied rooting damage during five-years of feral swine control at Avon Park Air Force Range, a significant botanical biodiversity hotspot in peninsular Florida with many globally imperiled plant species and communities. While control reduced swine abundance, remaining animals consistently rooted the 49 studied sites in both middle-dry season (MDS) and late-dry season (LDS) each year. At each study site, we measured rooting with sub-meter accuracy. Neither total nor proportional area rooted differed in either season, across study years, or among plant community types: herbaceous seepage slopes, wet pine savannas, wet grasslands. The proportion of sites with damage during MDS was at least 25 % less than pre-control baseline. During LDS, the proportion of sites with damage increased over years but remained below the initial 2 years’ MDS results. Fresh rooting frequency (rooting \u3c1 \u3eweek-old) across sites dropped precipitously from baseline and remained low for MDS. Fresh rooting frequency among sites during LDS was lower than MDS for all but year two of the study. Canopied habitatwetlands, integrating swine control into other compatible land use practices, and improving swine control efficacy. While we measured damage amounts at each site very accurately, our approach of also considering frequency of rooting and frequency of fresh rooting across sites offers low-labor means to broadly assess swine damage and control efficacy at large geographic scales because in-field measurements of damage amounts are not needed

An integrated MEMS system for turbulent boundary layer control

The goal of this project is a first attempt to achieve active drag reduction using a large-scale integrated MEMS system. Previously, we have reported the successful development of a shear-stress imager which allows us to "see" surface vortices (1996). Here we present the promising results of the interaction between micro flap actuators and vortices. It is found that microactuators can actually reduce drag to values even lower than the drag associated with pure laminar flow, and that the microactuators can reduce shear stress values in turbulent flow as well. Based on these results, we have attempted the first totally integrated system that consists of 18 shear stress sensors, 3 magnetic flap-type actuators and control electronics for use in turbulent boundary layer control studies