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Search Results: 1 - 10 of 270127 matches for " Catherine H. Wang "
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A Hybrid Algorithm to Address Ambiguities in Deformable Image Registration for Radiation Therapy  [PDF]
Song Gao, Yongbin Zhang, Jinzhong Yang, Catherine H. Wang, Lifei Zhang, Laurence E. Court, Lei Dong
International Journal of Medical Physics,Clinical Engineering and Radiation Oncology (IJMPCERO) , 2012, DOI: 10.4236/ijmpcero.2012.12007
Abstract: We proposed the use of a hybrid deformable image registration approach that combines compact-support radial basis functions (CSRBF) spline registration with intensity-based image registration. The proposed method first uses the pre-viously developed image intensity-based method to achieve voxel-by-voxel correspondences over the entire image re-gion. Next, for those areas of inaccurate registration, a sparse set of landmark correspondences was defined for local deformable image registration using a multi-step CSRBF approach. This hybrid registration takes advantage of both intensity-based method for automatic processing of entire images and the CSRBF spline method for fine adjustment over specific regions. The goal of using this hybrid registration is to locally control the quality of registration results in specific regions of interest with minimal human intervention. The major applications of this approach in radiation ther-apy are for the corrections of registration failures caused by various imaging artifacts resulting in, low image contrast, and non-correspondence situations where an object may not be imaged in both target and source images. Both synthetic and real patient data have been used to evaluate this hybrid method. We used contours mapping to validate the accuracy of this method on real patient image. Our studies demonstrated that this hybrid method could improve overall registra-tion accuracy with moderate overhead. In addition, we have also shown that the multi-step CSRBF registration proved to be more effective in handling large deformations while maintaining the smoothness of the transformation than origi-nal CSRBF.
Quasifinite representations of classical Lie subalgebras of W_{1+infty}
Victor G. Kac,Weiqiang Wang,Catherine H. Yan
Mathematics , 1998,
Abstract: We show that there are precisely two, up to conjugation, anti-involutions sigma_{\pm} of the algebra of differential operators on the circle preserving the principal gradation. We classify the irreducible quasifinite highest weight representations of the central extension \hat{D}^{\pm} of the Lie subalgebra of this algebra fixed by - sigma_{\pm}, and find the unitary ones. We realize them in terms of highest weight representations of the central extension of the Lie algebra of infinite matrices with finitely many non-zero diagonals over the truncated polynomial algebra C[u] / (u^{m+1}) and its classical Lie subalgebras of B, C and D types. Character formulas for positive primitive representations of \hat{D}^{\pm} (including all the unitary ones) are obtained. We also realize a class of primitive representations of \hat{D}^{\pm} in terms of free fields and establish a number of duality results between these primitive representations and finite-dimensional irreducible representations of finite-dimensional Lie groups and supergroups. We show that the vacuum module V_c of \hat{D}^+ carries a vertex algebra structure and establish a relationship between V_c for half-integral central charge c and W-algebras.
Fluorescence blinking statistics from single CdSe nanorods
Siying Wang,Claudia Querner,Thomas Emmons,Marija Drndic,Catherine H. Crouch
Physics , 2006,
Abstract: We report fluorescence blinking statistics measured from single CdSe nanorods (NRs) of seven different sizes with aspect ratio ranging from 3 to 11. This study included core/shell CdSe/ZnSe NRs and core NRs with two different surface ligands producing different degrees of surface passivation. We compare the findings for NRs to our measurements of blinking statistics from spherical CdSe core and CdSe/ZnS core/shell nanocrystals (NCs). We find that for both NRs and spherical NCs, the off-time probability distributions are well described by a power law, while the on-time probability distributions are best described by a truncated power law. The measured crossover time is indistinguishable within experimental uncertainty for core and core/shell NRs, and for core NRs with different ligands, indicating that surface passivation does not affect the blinking statistics significantly. We find that at fixed excitation intensity, the inverse crossover time increases approximately linearly with increasing NR aspect ratio; for a given sample, the inverse crossover time increases very gradually with increasing excitation intensity. The measured per-particle absorption cross section for all samples indicates that the change in NR absorption cross-section with sample size can account for some but not all of the differences in crossover time. This suggests that the degree of quantum confinement may be partially responsible for the aspect ratio dependence of the crossover time.
Mixed Statistics on 01-Fillings of Moon Polyominoes
William Y. C. Chen,Andrew Y. Z. Wang,Catherine H. Yan,Alina F. Y. Zhao
Mathematics , 2009,
Abstract: We establish a stronger symmetry between the numbers of northeast and southeast chains in the context of 01-fillings of moon polyominoes. Let $\M$ be a moon polyomino with $n$ rows and $m$ columns. Consider all the 01-fillings of $\M$ in which every row has at most one 1. We introduce four mixed statistics with respect to a bipartition of rows or columns of $\M$. More precisely, let $S \subseteq \{1,2,..., n\}$ and $\mathcal{R}(S)$ be the union of rows whose indices are in $S$. For any filling $M$, the top-mixed (resp. bottom-mixed) statistic $\alpha(S; M)$ (resp. $\beta(S; M)$) is the sum of the number of northeast chains whose top (resp. bottom) cell is in $\mathcal{R}(S)$, together with the number of southeast chains whose top (resp. bottom) cell is in the complement of $\mathcal{R}(S)$. Similarly, we define the left-mixed and right-mixed statistics $\gamma(T; M)$ and $\delta(T; M)$, where $T$ is a subset of the column index set $\{1,2,..., m\}$. Let $\lambda(A; M)$ be any of these four statistics $\alpha(S; M)$, $\beta(S; M)$, $\gamma(T; M)$ and $\delta(T; M)$, we show that the joint distribution of the pair $(\lambda(A; M), \lambda(\bar A; M))$ is symmetric and independent of the subsets $S, T$. In particular, the pair of statistics $(\lambda(A;M), \lambda(\bar A; M))$ is equidistributed with $(\se(M),\ne(M))$, where $\se(M)$ and $\ne(M)$ are the numbers of southeast chains and northeast chains of $M$, respectively.
Facile Synthesis of Highly Aligned Multiwalled Carbon Nanotubes from Polymer Precursors
Catherine Y. Han,Zhi-Li Xiao,H. Hau Wang,Xiao-Min Lin,Susana Trasobares,Russell E. Cook
Journal of Nanomaterials , 2009, DOI: 10.1155/2009/562376
Abstract: We report a facile one-step approach which involves no flammable gas, no catalyst, and no in situ polymerization for the preparation of well-aligned carbon nanotube array. A polymer precursor is placed on top of an anodized aluminum oxide (AAO) membrane containing regular nanopore arrays, and slow heating under Ar flow allows the molten polymer to wet the template through adhesive force. The polymer spread into the nanopores of the template to form polymer nanotubes. Upon carbonization the resulting multi-walled carbon nanotubes duplicate the nanopores morphology precisely. The process is demonstrated for 230, 50, and 20 nm pore membranes. The synthesized carbon nanotubes are characterized with scanning/transmission electron microscopies, Raman spectroscopy, and resistive measurements. Convenient functionalization of the nanotubes with this method is demonstrated through premixing CoPt nanoparticles in the polymer precursors.
A Genome-Wide RNAi Screen Identifies FOXO4 as a Metastasis-Suppressor through Counteracting PI3K/AKT Signal Pathway in Prostate Cancer
Bing Su, Lingqiu Gao, Catherine Baranowski, Bryan Gillard, Jianmin Wang, Ryan Ransom, Hyun-Kyung Ko, Irwin H. Gelman
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0101411
Abstract: Activation of the PI3K/AKT signal pathway is a known driving force for the progression to castration-recurrent prostate cancer (CR-CaP), which constitutes the major lethal phenotype of CaP. Here, we identify using a genomic shRNA screen the PI3K/AKT-inactivating downstream target, FOXO4, as a potential CaP metastasis suppressor. FOXO4 protein levels inversely correlate with the invasive potential of a panel of human CaP cell lines, with decreased mRNA levels correlating with increased incidence of clinical metastasis. Knockdown (KD) of FOXO4 in human LNCaP cells causes increased invasion in vitro and lymph node (LN) metastasis in vivo without affecting indices of proliferation or apoptosis. Increased Matrigel invasiveness was found by KD of FOXO1 but not FOXO3. Comparison of differentially expressed genes affected by FOXO4-KD in LNCaP cells in culture, in primary tumors and in LN metastases identified a panel of upregulated genes, including PIP, CAMK2N1, PLA2G16 and PGC, which, if knocked down by siRNA, could decrease the increased invasiveness associated with FOXO4 deficiency. Although only some of these genes encode FOXO promoter binding sites, they are all RUNX2-inducible, and RUNX2 binding to the PIP promoter is increased in FOXO4-KD cells. Indeed, the forced expression of FOXO4 reversed the increased invasiveness of LNCaP/shFOXO4 cells; the forced expression of FOXO4 did not alter RUNX2 protein levels, yet it decreased RUNX2 binding to the PIP promoter, resulting in PIP downregulation. Finally, there was a correlation between FOXO4, but not FOXO1 or FOXO3, downregulation and decreased metastasis-free survival in human CaP patients. Our data strongly suggest that increased PI3K/AKT-mediated metastatic invasiveness in CaP is associated with FOXO4 loss, and that mechanisms to induce FOXO4 re-expression might suppress CaP metastatic aggressiveness.
El corrido y la bola suriana: el canto popular como arma ideológica y operador de identidad
Catherine Hèau
Estudios sobre las Culturas Contemporaneas , 1989,
Abstract: Through the study of two musical generes, the "bola suriana" and the "corrido Zapatista" of Mexican revolution, the author consisely analyzes the popular song and its ideological power as a mechanism of production of cultural identities.
Explicit descent over X(3) and X(5)
Catherine H. O'Neil
Mathematics , 2002,
Abstract: We split the program of explicit descent of elliptic curves into two parts. For $n=3$ and $n=5,$ we first display a model for the universal elliptic curve $E$ with full level $n$ structure and describe the map of rational points of $E$ to the cohomology group $H^1(G, E[n]).$ Second, we find models in $\PP^{n-1}$ of principal homogeneous spaces of $E$ corresponding to all possible elements of $H^1(G, E[n]),$ i.e. for those elements with trivial period-index obstruction. For this we use the relationship established in \cite{me2} between the period-index obstruction and the norm symbol, a generalization of the Hilbert symbol.
Expanded CAG/CTG Repeat DNA Induces a Checkpoint Response That Impacts Cell Proliferation in Saccharomyces cerevisiae
Rangapriya Sundararajan,Catherine H. Freudenreich
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1001339
Abstract: Repetitive DNA elements are mutational hotspots in the genome, and their instability is linked to various neurological disorders and cancers. Although it is known that expanded trinucleotide repeats can interfere with DNA replication and repair, the cellular response to these events has not been characterized. Here, we demonstrate that an expanded CAG/CTG repeat elicits a DNA damage checkpoint response in budding yeast. Using microcolony and single cell pedigree analysis, we found that cells carrying an expanded CAG repeat frequently experience protracted cell division cycles, persistent arrests, and morphological abnormalities. These phenotypes were further exacerbated by mutations in DSB repair pathways, including homologous recombination and end joining, implicating a DNA damage response. Cell cycle analysis confirmed repeat-dependent S phase delays and G2/M arrests. Furthermore, we demonstrate that the above phenotypes are due to the activation of the DNA damage checkpoint, since expanded CAG repeats induced the phosphorylation of the Rad53 checkpoint kinase in a rad52Δ recombination deficient mutant. Interestingly, cells mutated for the MRX complex (Mre11-Rad50-Xrs2), a central component of DSB repair which is required to repair breaks at CAG repeats, failed to elicit repeat-specific arrests, morphological defects, or Rad53 phosphorylation. We therefore conclude that damage at expanded CAG/CTG repeats is likely sensed by the MRX complex, leading to a checkpoint response. Finally, we show that repeat expansions preferentially occur in cells experiencing growth delays. Activation of DNA damage checkpoints in repeat-containing cells could contribute to the tissue degeneration observed in trinucleotide repeat expansion diseases.
Maltrato al anciano: "una realidad oculta en nuestra sociedad"
Rodríguez H. Shirley Catherine
Avances en Enfermería , 1996,
Abstract: El maltrato al anciano es un hecho cotidiano, no reconocido socialmente como tal, por el contrario, el maltrato es considerado un cuento normal al que se ve expuesto un gran número de personas; que afecta el sistema familiar y a cada uno de sus miembros. Conscientes de la importancia del reconocimiento, identificación, manejo oportuno y adecuado y la intervención que enfermería realice en la situación del maltrato al anciano, se podrá forjar un camino hacia el cambio. La concepción de envejecimiento que tiene la sociedad favorece el maltrato al anciano, situación tan común como el maltrato de esposas y ni os. Sumado a ello, los casos de maltrato al anciano son poco reconocidos y denunciados; las situaciones que evidencian el maltrato son negadas o justificadas por la familia, lo cual dificulta el reconocimiento de este hecho.
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