High throughput quantification of protein expression of cancer antigens in tissue microarray using quantum dot nanocrystals

We developed and validated a novel method for quantifying protein expression of cancer tumors in an accurate, sensitive, and high throughput format. This technique integrates quantum dots, tissue microarray, optical spectroscopy, and algorithm design for analysis of tumor biopsies. The integration of this method for tissue analysis in the clinic bears potential impact for improving the diagnosis and treatment of cancer.     

Fabrication of nanostructure and formation of nanocrystal for non-volatile memory

In this work, we have demonstrated that the nanocrystal created by combining the self-assembled block copolymer thin film with regular semiconductor processing can be applicable to non-volatile memory device with increased charge storage capacity over planar structures. Self-assembled block copolymer thin film for nanostructures with critical dimensions below photolithographic resolution limits has been used during all experiments. Nanoporous thin film from PS-b-PMMA diblock copolymer thin film with selective removal of PMMA domains was used to fabricate nanostructure and nanocrystal. We have also reported about surface morphologies and electrical properties of the nano-needle structure formed by RIE technique. The details of nanoscale pattern of the very uniform arrays using RIE are presented. We fabricated different surface structure of nanoscale using block copolymer. We also deposited Si-rich SiNx layer using ICP-CVD on the silicon surface of nanostructure. The deposited films were studied after annealing. PL studies demonstrated nanocrystal in Si-rich SiNx film on nanostructure of silicon.     

Synthetic-aperture chirp confocal imaging

An imaging system that combines synthetic-aperture imaging, holography, and an optical chirp with confocal imaging is described and analyzed. Comparisons are made with synthetic-aperture radar systems. Adaptation of several synthetic-aperture radar techniques to the optical counterparts is suggested.     

Terahertz wave propagation in one-dimensional periodic dielectrics

We demonstrate the temporal evolution of terahertz (THz) wave propagation in one-dimensional periodic dielectrics. Distributed Bragg reflectors and a resonant cavity are investigated: The structures involve air gaps interleaved between polymer films. Transmitted and reflected broadband THz waves are measured by means of THz time-domain spectroscopy. The experimental results agree well with transfer matrix calculations.     

Comparison of daytime and nighttime concentration profiles and size distributions of ultrafine particles near a major highway

Previously we have conducted systematic measurements of the concentration and size distribution of ultrafine particles in the vicinity of major highways during daytime in Los Angeles. The present study compares these with similar measurements made at night. Particle number concentration was measured by a condensation particle counter (CPC) and size distributions in the size range from 7 to 300 nm were measured by a scanning mobility particle sizer (SMPS). Measurements were taken at 30, 60, 90, 150, and 300 m upwind and downwind from the center of the 1-405 freeway. Average traffic flow at night was about 25% of that observed during the day. Particle number concentration measured at 30 m downwind from the freeway was 80% of previous daytime measurements. This discrepancy between changes in traffic counts and particle number concentrations is apparently due to the decreased temperature, increased relative humidity, and lower wind speed at night. Particle size distributions do not change as dramatically as they did during the daytime. Particle number concentration decays exponentially downwind from the freeway similarly to what was observed during the day, but at a slower rate. No particle number concentration gradient has been observed for the upwind side of the freeway. No PM2.5 and very weak PM10 concentration gradients were observed downwind of thefreeway at night. Ultrafine particle number concentration measured at 300 m downwind from the freeway was still distinguishably higher than upwind background concentration at night. These data may be used to help estimate exposure to ultrafine particles in the vicinity of major highways for epidemiology studies.     

Change of dissolved gaseous mercury concentrations in a southern reservoir lake (Tennessee) following seasonal variation of solar radiation

A 12-month field study was conducted consecutively from June 2003 to May 2004 to quantify temporal variations of dissolved gaseous mercury (DGM) concentrations in Cane Creek Lake, a southern reservoir lake (Cookeville, TN). Diurnal changes of DGM concentrations in two periods (morning increase vs afternoon decrease with an around-noon peak) were observed, and the changes closely followed daily solar radiation variation trends. The diurnal patterns prevailed in the late spring and summer, but became vague in the late fall and winter. The monthly mean DGM concentrations peaked at 40.8 pg L(-1) in July and reached the lowest at 14.2 pg L(-1) in December and 21.9 pg L(-1) in January; this DGM concentration change closely followed the monthly mean solar radiation variation trend. The increase of the lake DGM concentration from January to July and its decrease from July to December mirror the typical daily rhythm of DGM concentration variations in the two periods. This finding supports the following hypothesis: The natural phenomenon of daily oscillation of freshwater DGM concentrations that follows diurnal solar radiation variation would manifest on a seasonal scale. High DGM concentrations were found in the spring and summer and low in the fall and winter (seasonal mean: 34.2, 37.5, 20.0, 24.4 pg L(-1), respectively). This seems to suggest an annual occurrence of two periods of the seasonal DGM level fluctuation (spring and summer high vs fall and winter low DGM levels). Linear relationships of the monthly mean DGM concentrations were found with the monthly mean global solar radiation (R2 = 0.82, P < 0.05) and UVA radiation (R2 = 0.84, P < 0.05). Linear relationships of the seasonal mean DGM concentrations were also found with the seasonal mean global solar radiation (R2 = 0.85, P = 0.08) and UVA radiation (R2 = 0.93, P < 0.05).     

Comparison of ultraviolet absorbance, chemiluminescence, and DOAS instruments for ambient ozone monitoring

This paper evaluates the accuracy of ozone measurements made by monitors that determine ozone concentrations in ambient air by UV absorption. These monitors are typically used to measure ozone for the purpose of establishing local compliance to air-quality standards. The study was predicated by the concern that commercially available UV absorbance O3 monitors may be subject to interference from volatile organic carbon (VOC) species that absorb light at 254 nm. To test for these and other effects, we compared simultaneous O3 measurements made by a commercial UV O3 monitor with an O3-NO chemiluminescence instrument, which is not subject to interference by VOC compounds. The comparisons were carried out in the summers of 1999 and 2000 at urban/industrial sites in Nashville and Houston, and in 2004 aboard a ship in the Gulf of Maine. In the two urban areas, we also compared the 03 measurements from these two methods with O3 measurements made by a long-path differential optical absorption spectrometer (DOAS). Our tests indicate that, with well-maintained monitors, there are no significant interferences even in areas with significant ambient concentrations of potentially interfering VOCs.     

Welfare effects of the use of recombinant bovine somatotropin in the USA

The welfare effects of increased milk production associated with the use of recombinant bovine somatotropin (rBST) on dairy operations in the USA were examined for 1996. Results that derived from three different estimates of the milk-production response to rBST were evaluated and compared. One estimate, derived from a survey of dairy producers in Connecticut, led to economic-impact estimates that were not statistically significant. A second, derived from a national survey that concentrated on the health and management of dairy cattle, led to estimates that were unbelievably high. A third, derived from a national survey that concentrated on the economics of dairy producers, provided the most reasonable estimates of economic impacts. Results of economic analysis, using the latter results, indicated that if rBST had not caused milk production to increase, then the market price of milk would have been 2.2 +/- 1.5 cents/kg higher, and the total value of the milk produced would have risen from Dollars 23.0 +/- 0.6 billion to Dollars 24.1 +/- 1.0 billion. A welfare analysis demonstrated that the increased milk production (and the reduced market price) associated with the use of rBST in the USA caused the economic surplus of consumers to rise by Dollars 1.5 +/- 1.0 billion, while the economic surplus of dairy producers fell by Dollars 1.1 +/- Dollars 0.8 billion. Increased milk production associated with rBST yielded a total gain to the US economy of Dollars 440 +/- 280 million. An analysis of annual percent changes in the number of dairy cows per operation, milk production per cow, total milk production, total number of dairy cows, and total number of dairy operations in the USA suggested that the dairy industry's long-term economic growth path was stable from 1989-2001 inclusive, and did not receive a shock resulting from the introduction of rBST.     

Modeling the impact of climate variability on diarrhea-associated diseases in Taiwan (1996-2007)

Diarrhea is an important public health problem in Taiwan. Climatic changes and an increase in extreme weather events (extreme heat, drought or rainfalls) have been strongly linked to the incidence of diarrhea-associated disease.This study investigated and quantified the relationship between climate variations and diarrhea-associated morbidity in subtropical Taiwan. Specifically, this study analyzed the local climatic variables and the number of diarrhea-associated infection cases from 1996 to 2007. This study applied a climate variation-guided Poisson regression model to predict the dynamics of diarrhea-associated morbidity. The proposed model allows for climate factors (relative humidity, maximum temperature and the numbers of extreme rainfall), autoregression, long-term trends and seasonality, and a lag-time effect. Results indicated that the maximum temperature and extreme rainfall days were strongly related to diarrhea-associated morbidity. The impact of maximum temperature on diarrhea-associated morbidity appeared primarily among children (0-14 years) and older adults (40-64 years), and had less of an effect on adults (15-39 years). Otherwise, relative humidity and extreme rainfall days significantly contributed to the diarrhea-associated morbidity in adult. This suggested that children and older adults were the most susceptible to diarrhea-associated morbidity caused by climatic variation. Because climatic variation contributed to diarrhea morbidity in Taiwan, it is necessary to develop an early warning system based on the climatic variation information for disease control management.     

Hybrid integrate-and-fire model of a bursting neuron

We present a reduction of a Hodgkin-Huxley (HH)--style bursting model to a hybridized integrate-and-fire (IF) formalism based on a thorough bifurcation analysis of the neuron's dynamics. The model incorporates HH--style equations to evolve the subthreshold currents and includes IF mechanisms to characterize spike events and mediate interactions between the subthreshold and spiking currents. The hybrid IF model successfully reproduces the dynamic behavior and temporal characteristics of the full model over a wide range of activity, including bursting and tonic firing. Comparisons of timed computer simulations of the reduced model and the original model for both single neurons and moderately sized networks (n < or = 500) show that this model offers improvement in computational speed over the HH--style bursting model.