X-Ray Diffuse Scattering

Contains research summary and reports on two research projects.Joint Services Electronics Program (Contract DAAL03-86-K-0002)Joint Services Electronics Program (Contract DAAL03-89-C-0001

Diffusion on a heptagonal lattice

We study the diffusion phenomena on the negatively curved surface made up of congruent heptagons. Unlike the usual two-dimensional plane, this structure makes the boundary increase exponentially with the distance from the center, and hence the displacement of a classical random walker increases linearly in time. The diffusion of a quantum particle put on the heptagonal lattice is also studied in the framework of the tight-binding model Hamiltonian, and we again find the linear diffusion like the classical random walk. A comparison with diffusion on complex networks is also made.Comment: 5 pages, 6 figure

Synchrotron X-Ray Studies of Surface Disordering

Contains an introduction and reports on three research projects.Joint Services Electronics Program Contract DAAL03-92-C-000

Charge-spin correlation in van der Waals antiferromagenet NiPS3

Strong charge-spin coupling is found in a layered transition-metal trichalcogenide NiPS3, a van derWaals antiferromagnet, from our study of the electronic structure using several experimental and theoretical tools: spectroscopic ellipsometry, x-ray absorption and photoemission spectroscopy, and density-functional calculations. NiPS3 displays an anomalous shift in the optical spectral weight at the magnetic ordering temperature, reflecting a strong coupling between the electronic and magnetic structures. X-ray absorption, photoemission and optical spectra support a self-doped ground state in NiPS3. Our work demonstrates that layered transition-metal trichalcogenide magnets are a useful candidate for the study of correlated-electron physics in two-dimensional magnetic material.Comment: 6 pages, 3 figur

Comparisons of Pediatric Patients who Visited to the Pediatric Emergency Department and the General Emergency Department

Purpose In 2010 and 2011, the Korean Ministry of Health and Welfare designated 2 and 4 Pediatric Emergency Centers, respectively. This study was conducted to examine the characteristics of pediatric patients who visited the pediatric emergency department (PED) compared with the general emergency department (GED). Methods We used the National Emergency Medical Department Information System (NEDIS) data on pediatric visits (<19 years old), from July 1 to December 31, 2011. We analyzed patients' general characteristics, number, severity, and length of stay (LOS). Results A total of 709,050 children visited 132 GEDs and 6 PEDs during the study period. Male patients of PED was 57.6%, and the mean age of PED was younger than GED (4.7±5.0 yr vs. 5.7±5.5 yr). There were more numbers of patient visitations per center, number of critically ill or injured patients per center, number of admitted patients per center, and the number of operation per center in PED than GED. LOS of overall, discharged, and transferred patients was the same between PED and GED; however, LOS of admitted patients was longer in PED. Conclusion We observed that PEDs did not function as a tertiary referral center. Further research is needed to find the reason for such phenomenon and provide possible solutions

Activation of PERK Signaling Attenuates Aβ-Mediated ER Stress

Alzheimer's disease (AD) is characterized by the deposition of aggregated beta-amyloid (Aβ), which triggers a cellular stress response called the unfolded protein response (UPR). The UPR signaling pathway is a cellular defense system for dealing with the accumulation of misfolded proteins but switches to apoptosis when endoplasmic reticulum (ER) stress is prolonged. ER stress is involved in neurodegenerative diseases including AD, but the molecular mechanisms of ER stress-mediated Aβ neurotoxicity still remain unknown. Here, we show that treatment of Aβ triggers the UPR in the SK-N-SH human neuroblastoma cells. Aβ mediated UPR pathway accompanies the activation of protective pathways such as Grp78/Bip and PERK-eIF2α pathway, as well as the apoptotic pathways of the UPR such as CHOP and caspase-4. Knockdown of PERK enhances Aβ neurotoxicity through reducing the activation of eIF2α and Grp8/Bip in neurons. Salubrinal, an activator of the eIF2α pathway, significantly increased the Grp78/Bip ER chaperone resulted in attenuating caspase-4 dependent apoptosis in Aβ treated neurons. These results indicate that PERK-eIF2α pathway is a potential target for therapeutic applications in neurodegenerative diseases including AD

X-Ray Diffuse Scattering

Contains introduction and reports on three research projects.Joint Services Electronics Program DAAL03-89-C-000