105 research outputs found
Transport of Surface States in the Bulk Quantum Hall Effect
The two-dimensional surface of a coupled multilayer integer quantum Hall
system consists of an anisotropic chiral metal. This unusual metal is
characterized by ballistic motion transverse and diffusive motion parallel
(\hat{z}) to the magnetic field. Employing a network model, we calculate
numerically the phase coherent two-terminal z-axis conductance and its
mesoscopic fluctuations. Quasi-1d localization effects are evident in the limit
of many layers. We consider the role of inelastic de-phasing effects in
modifying the transport of the chiral surface sheath, discussing their
importance in the recent experiments of Druist et al.Comment: 9 pages LaTex, 9 postscript figures included using eps
Conductance fluctuations at the integer quantum Hall plateau transition
We study numerically conductance fluctuations near the integer quantum Hall
effect plateau transition. The system is presumed to be in a mesoscopic regime,
with phase coherence length comparable to the system size. We focus on a
two-terminal conductance G for square samples, considering both periodic and
open boundary conditions transverse to the current. At the plateau transition,
G is broadly distributed, with a distribution function close to uniform on the
interval between zero and one in units of e^2/h. Our results are consistent
with a recent experiment by Cobden and Kogan on a mesoscopic quantum Hall
effect sample.Comment: minor changes, 5 pages LaTex, 7 postscript figures included using
epsf; to be published Phys. Rev. B 55 (1997
Criticality in the two-dimensional random-bond Ising model
The two-dimensional (2D) random-bond Ising model has a novel multicritical
point on the ferromagnetic to paramagnetic phase boundary. This random phase
transition is one of the simplest examples of a 2D critical point occurring at
both finite temperatures and disorder strength. We study the associated
critical properties, by mapping the random 2D Ising model onto a network model.
The model closely resembles network models of quantum Hall plateau transitions,
but has different symmetries. Numerical transfer matrix calculations enable us
to obtain estimates for the critical exponents at the random Ising phase
transition. The values are consistent with recent estimates obtained from
high-temperature series.Comment: minor changes, 7 pages LaTex, 8 postscript figures included using
epsf; to be published Phys. Rev. B 55 (1997
Polyp Clearance via Operative and Endoscopic Polypectomy in Patients With Peutz-Jeghers Syndrome After Multiple Small Bowel Resections
Peutz-Jeghers syndrome is an autosomal dominant inherited disease that manifests as a combination of mucocutaneous pigmentation and gastrointestinal hamartomatous polyps that usually cause intussusception and intestinal hemorrhage. We report the case of a 40-year-old male patient who was diagnosed 20 years ago and had previously undergone 3 intestinal resection surgeries. This time, with the use of combined operative and endoscopic polypectomy, more than 100 polyps were removed. This technique is useful for providing a "clean" small intestine that allows the patient a long interval between laparotomies and reduces the complications associated with multiple laparotomies and resections
Targeting metastatic breast cancer with peptide epitopes derived from autocatalytic loop of Prss14/ST14 membrane serine protease and with monoclonal antibodies
Background
In order to develop a new immunotherapeutic agent targeting metastatic breast cancers, we chose to utilize autocatalytic feature of the membrane serine protease Prss14/ST14, a specific prognosis marker for ER negative breast cancer as a target molecule.
Methods
The study was conducted using three mouse breast cancer models, 4 T1 and E0771 mouse breast cancer cells into their syngeneic hosts, and an MMTV-PyMT transgenic mouse strain was used. Prss14/ST14 knockdown cells were used to test function in tumor growth and metastasis, peptides derived from the autocatalytic loop for activation were tested as preventive metastasis vaccine, and monoclonal and humanized antibodies to the same epitope were tested as new therapeutic candidates. ELISA, immunoprecipitation, Immunofluorescent staining, and flow cytometry were used to examine antigen binding. The functions of antibodies were tested in vitro for cell migration and in vivo for tumor growth and metastasis.
Results
Prss14/ST14 is critically involved in the metastasis of breast cancer and poor survival rather than primary tumor growth in two mouse models. The epitopes derived from the specific autocatalytic loop region of Prss14/ST14, based on structural modeling acted as efficient preventive metastasis vaccines in mice. A new specific monoclonal antibody mAb3F3 generated against the engineered loop structure could reduce cell migration, eliminate metastasis in PyMT mice, and can detect the Prss14/ST14 protein expressed in various human cancer cells. Humanized antibody huAb3F3 maintained the specificity and reduced the migration of human breast cancer cells in vitro.
Conclusion
Our study demonstrates that Prss14/ST14 is an important target for modulating metastasis. Our newly developed hybridoma mAbs and humanized antibody can be further developed as new promising candidates for the use in diagnosis and in immunotherapy of human metastatic breast cancer.This work is supported in part by the National Research Foundation (NRF) grant funded by the Korea government (MEST) (No. 2013R1A1A2009892 and No. 2017R1A2B4008109) and Inha Univeristy Research Grant awarded to MGK and (No. 2015R1A2A1A15054021) to SHK
Comparison of PM2.5 in Seoul, Korea Estimated from the Various Ground-Based and Satellite AOD
Based on multiple linear regression (MLR) models, we estimated the PM2.5 at Seoul using a number of aerosol optical depth (AOD) values obtained from ground-based and satellite remote sensing observations. To construct the MLR model, we consider various parameters related to the ambient meteorology and air quality. In general, all AOD values resulted in the high quality of PM2.5 estimation through the MLR method: mostly correlation coefficients >~0.8. Among various polar-orbit satellite AODs, AOD values from the MODIS measurement contribute to better PM2.5 estimation. We also found that the quality of estimated PM2.5 shows some seasonal variation; the estimated PM2.5 values consistently have the highest correlation with in situ PM2.5 in autumn, but are not well established in winter, probably due to the difficulty of AOD retrieval in the winter condition. MLR modeling using spectral AOD values from the ground-based measurements revealed that the accuracy of PM2.5 estimation does not depend on the selected wavelength. Although all AOD values used in this study resulted in a reasonable accuracy range of PM2.5 estimation, our analyses of the difference in estimated PM2.5 reveal the importance of utilizing the proper AOD for the best quality of PM2.5 estimation
Efficient pathway enrichment and network analysis of GWAS summary data using GSA-SNP2
Pathway-based analysis in genome-wide association study (GWAS) is being widely used to uncover novel multi-genic functional associations. Many of these pathway-based methods have been used to test the enrichment of the associated genes in the pathways, but exhibited low powers and were highly affected by free parameters. We present the novel method and software GSA-SNP2 for pathway enrichment analysis of GWAS P-value data. GSA-SNP2 provides high power, decent type I error control and fast computation by incorporating the random set model and SNP-count adjusted gene score. In a comparative study using simulated and real GWAS data, GSA-SNP2 exhibited high power and best prioritized gold standard positive pathways compared with six existing enrichment-based methods and two self-contained methods (alternative pathway analysis approach). Based on these results, the difference between pathway analysis approaches was investigated and the effects of the gene correlation structures on the pathway enrichment analysis were also discussed. In addition, GSA-SNP2 is able to visualize protein interaction networks within and across the significant pathways so that the user can prioritize the core subnetworks for further studies. GSA-SNP2 is freely available at https://sourceforge.net/projects/gsasnp2
Clinical utility of TERT promoter mutations and ALK rearrangement in thyroid cancer patients with a high prevalence of the BRAF V600E mutation
An Optimal Management Strategy of Carbon Forestry with a Stochastic Price
An analysis for the value of carbon forestry needs to be provided for the successful establishment of the carbon offset market in Korea. We present an optimal management strategy for a forest owner who participates in the offset market. Given a stochastic process of the timber price following a geometric Brownian motion, the profit maximization problem of the forest owner is solved. The model finds an optimal harvest time in the presence of the carbon and timber revenues with opposing time effects. Sensitivity analysis is performed with respect to the volatility rate of the timber price and the discount rate. The presented model is applied to the study of the Korean larch case to identify the threshold timber price above which it is optimal to harvest trees
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