NaGdF4:Eu3+ Nanoparticles for Enhanced X-ray Excited Optical Imaging.

X-ray luminescent nanoparticles (NPs), including lanthanide fluorides, have been evaluated for application to deep tissue in vivo molecular imaging using optical tomography. A combination of high material density, higher atomic number and efficient NIR luminescence from compatible lanthanide dopant ions indicates that particles that consist of ALnF4 (A = alkaline, Ln = lanthanide element) may offer a very attractive class of materials for high resolution, deep tissue imaging with X-ray excitation. NaGdF4:Eu3+ NPs produced an X-ray excited luminescence that was among the most efficient of nanomaterials that have been studied thus far. We have systematically studied factors such as (a) the crystal structure that changes the lattice environment of the doped Eu3+ ions within the unit cell; and extrinsic factors such as (b) a gold coating (with attendant biocompatibility) that couples to a plasmonic excitation, and (c) changes in the NPs surface properties via changes in the pH of the suspending medium-all with a significant impact on the X-ray excited luminescence of NaGdF4:Eu3+NPs. The luminescence from an optimally doped hexagonal phase NaGdF4:Eu3+ nanoparticle was 25% more intense compared to that of a cubic structure. We observed evidence of plasmonic reabsorption of midwavelength emission by a gold coating on hexagonal NaGdF4:Eu3+ NPs; fortunately, the NaGdF4:Eu3+ @Au core-shell NPs retained the efficient 5D0→7F4 NIR (692 nm) luminescence. The NaGdF4:Eu3+ NPs exhibited sensitivity to the ambient pH when excited by X-rays, an effect not seen with UV excitation. The sensitivity to the local environment can be understood in terms of the sensitivity of the excitons that are generated by the high energy X-rays (and not by UV photons) to crystal structure and to the surface state of the particles

Monitoring development control in Hong Kong a probit analysis of planning application for change in use and development in industrial zones /

Thesis (B.Sc)--University of Hong Kong, 2006.published_or_final_versio

Image Reconstruction with a LaBr3-based Rotational Modulator

A rotational modulator (RM) gamma-ray imager is capable of obtaining significantly better angular resolution than the fundamental geometric resolution defined by the ratio of detector diameter to mask-detector separation. An RM imager consisting of a single grid of absorbing slats rotating ahead of an array of a small number of position-insensitive detectors has the advantage of fewer detector elements (i.e., detector plane pixels) than required by a coded aperture imaging system with comparable angular resolution. The RM therefore offers the possibility of a major reduction in instrument complexity, cost, and power. A novel image reconstruction technique makes it possible to deconvolve the raw images, remove sidelobes, reduce the effects of noise, and provide resolving power a factor of 6 - 8 times better than the geometric resolution. A 19-channel prototype RM developed in our laboratory at Louisiana State University features 13.8 deg full-angle field of view, 1.9 deg geometric angular resolution, and the capability of resolving sources to within 35' separation. We describe the technique, demonstrate the measured performance of the prototype instrument, and describe the prospects for applying the technique to either a high-sensitivity standoff gamma-ray imaging detector or a satellite- or balloon-borne gamma-ray astronomy telescope.Comment: submitted to Nuclear Instrument & Methods, special edition: SORMA 2010 on June 16, 201

Cultural Inheritance and Fertility Outcomes: An Analysis from Evolutionary and Interdisciplinary Perspectives

Taking evolutionary and interdisciplinary perspectives, this study views the reproductive result as an evolutionary outcome that may be affected by parental characteristics through cultural inheritance. We hypothesize that inheriting more cultural traits from parents leads to a greater resemblance between fertility outcomes of the offspring and their parents. In societies that experience a demographic transition, a greater resemblance can be indicated by a higher level of fertility of the offspring and a sooner transition from union formation to childbearing. We operationalize inheriting cultural traits from parents as reporting a religious affiliation the same as those of their parents. Through analyzing data from the National Survey of Family Growth (NSFG) Cycle 6, our results show that inheriting the same religious traits from parents does have an effect on one’s fertility. In particular, women who reported the same religious affiliations as those of their parents reported a greater number of children. They tend to have births inside, rather than outside, of marriage. Inside marriage, they are also more likely to give births sooner, rather than later. These findings support our hypotheses and help to build a theoretical framework that explains the changes in fertility outcomes from an interdisciplinary perspective

Adaptive Statistical Iterative Reconstruction-V for Lung Nodule Analysis

Introduction: Low-dose CT in lung cancer screening has demonstrated benefits in select patients. As the traditional filtered back projection (FBP) technique is limited by poor image quality, adaptive statistical iterative reconstruction-V (ASIR-V) algorithm has been developed to achieve higher image quality with processing efficiency. Objective: To investigate the impact of various CT scan parameters on the semi-automated measurement of lung nodules using a Computer Aided Detection (CAD) program. Methods: This IRB-exempt phantom experiment was conducted with a CT scanner capable of ASIR-V algorithm. Eight lung nodules sized 5-12 mm, of solid or ground glass type, were placed inside a multipurpose chest phantom with or without fat slabs. Voltage (kV), current (mA), and ASIR-V levels were varied, and series of CT images were produced. A CAD program semiautomatically analyzed the series and produced nodule diameters and volumes. Nodule measurement variance and the significance of variables were analyzed by one-way ANOVA and univariate regression. Results: Nodule diameter and type contributed to error in both diameter and volume measurements. Current also impacted diameter measurement error. ASIR-V, kV, and fat slabs did not contribute to nodule measurement systematic error. On regression analysis, error is negatively related to mA and solid nodules, but is positively related to nodule diameter or volume. Discussion: These results reinforce that nodule size, type, and mA have the highest influence on CAD software performance nodule quantification accuracy. ASIR-V and kV do not significantly alter the measurement error but, instead, maintain the accuracy of nodule evaluation while minimizing radiation dose

Identification of antiviral roles for the exon-junction complex and nonsense-mediated decay in flaviviral infection.

West Nile virus (WNV) is an emerging mosquito-borne flavivirus, related to dengue virus and Zika virus. To gain insight into host pathways involved in WNV infection, we performed a systematic affinity-tag purification mass spectrometry (APMS) study to identify 259 WNV-interacting human proteins. RNA interference screening revealed 26 genes that both interact with WNV proteins and influence WNV infection. We found that WNV, dengue and Zika virus capsids interact with a conserved subset of proteins that impact infection. These include the exon-junction complex (EJC) recycling factor PYM1, which is antiviral against all three viruses. The EJC has roles in nonsense-mediated decay (NMD), and we found that both the EJC and NMD are antiviral and the EJC protein RBM8A directly binds WNV RNA. To counteract this, flavivirus infection inhibits NMD and the capsid-PYM1 interaction interferes with EJC protein function and localization. Depletion of PYM1 attenuates RBM8A binding to viral RNA, suggesting that WNV sequesters PYM1 to protect viral RNA from decay. Together, these data suggest a complex interplay between the virus and host in regulating NMD and the EJC

Studying Kaon-pion S-wave scattering in K-matrix formalism

We generalize our previous work on \pi\pi scattering to K\pi scattering, and re-analyze the experiment data of K\pi scattering below 1.6 GeV. Without any free parameter, we explain K\pi I=3/2 S-wave phase shift very well by using t-channel rho and u-channel K^* meson exchange. With the t-channel and u-channel meson exchange fixed as the background term, we fit the K\pi I=1/2 S-wave data of the LASS experiment quite well by introducing one or two s-channel resonances. It is found that there is only one s-channel resonance between K\pi threshold and 1.6 GeV, i.e., K_0^*(1430) with a mass around 1438~1486 MeV and a width about 346 MeV, while the t-channel rho exchange gives a pole at (450-480i) MeV for the amplitude.Comment: REVTeX4 file, 11 pages and 3 figure