The measurement of market power: short-run, long-run, and dynamic adjustment models

This study presents an industry analysis of market structure and demonstrates the use of theory-consistent models following the NEIO tradition. The objective of this dissertation is to measure the degree of market power within the context of each of three models: short-run, and long-run equilibrium models, and a dynamic cost of adjustment model with strategic capital investment; and to see how inferences of market power differ across the three cases. The models\u27 differences in this dissertation center on the role of investment in capital. Specification tests are conducted between the short-run versus the long-run, and the short-run versus the dynamic models. Time-series data from the U.S. transformer industry producers, 1958-1991 are used to estimate the models;The empirical results suggest that we can reject the hypothesis of price-taking behavior in the output market from the three models. The Lerner\u27s index is lower in the dynamic model than that in the static models. The specification test results show that the long-run and the dynamic models are rejected against the short-run model. However, the result of a joint test with the estimates of the adjustment cost and strategic effect parameters suggests the dynamic cost of adjustment model is superior to the long-run model. As for the strategic effect of capital investment in the dynamic model, the parameter estimate implies that we can reject the null hypothesis that there is no strategic effect of investment in the industry

Design of a Customized Multi-Directional Layered Deposition System Based on Part Geometry

Multi-Direction Layered Deposition (MDLD) reduces the need for supports by depositing on a part along multiple directions. This requires the design of a new mechanism to reorient the part, such that the deposition head can approach from different orientations. We present a customized compliant parallel kinematic machine design configured to deposit a set of part geometries. Relationships between the process planning for the MDLD of a part geometry and considerations in the design of the customized machine mechanism are illustrated. MDLD process planning is based on progressive part decomposition and kinematic machine design uses dual number algebra and screw theory.Mechanical Engineerin

Nano-structure fabrication of GaAs using AFM tip-induced local oxidation method: different doping types and plane orientations

In this study, we have fabricated nano-scaled oxide structures on GaAs substrates that are doped in different conductivity types of p- and n-types and plane orientations of GaAs(100) and GaAs(711), respectively, using an atomic force microscopy (AFM) tip-induced local oxidation method. The AFM-induced GaAs oxide patterns were obtained by varying applied bias from approximately 5 V to approximately 15 V and the tip loading forces from 60 to 180 nN. During the local oxidation, the humidity and the tip scan speed are fixed to approximately 45% and approximately 6.3 μm/s, respectively. The local oxidation rate is further improved in p-type GaAs compared to n-type GaAs substrates whereas the rate is enhanced in GaAs(100) compared to and GaAs(711), respectively, under the identical conditions. In addition, the oxide formation mechanisms in different doping types and plane orientations were investigated and compared with two-dimensional simulation results

MASKER: Masked Keyword Regularization for Reliable Text Classification

Pre-trained language models have achieved state-of-the-art accuracies on various text classification tasks, e.g., sentiment analysis, natural language inference, and semantic textual similarity. However, the reliability of the fine-tuned text classifiers is an often underlooked performance criterion. For instance, one may desire a model that can detect out-of-distribution (OOD) samples (drawn far from training distribution) or be robust against domain shifts. We claim that one central obstacle to the reliability is the over-reliance of the model on a limited number of keywords, instead of looking at the whole context. In particular, we find that (a) OOD samples often contain in-distribution keywords, while (b) cross-domain samples may not always contain keywords; over-relying on the keywords can be problematic for both cases. In light of this observation, we propose a simple yet effective fine-tuning method, coined masked keyword regularization (MASKER), that facilitates context-based prediction. MASKER regularizes the model to reconstruct the keywords from the rest of the words and make low-confidence predictions without enough context. When applied to various pre-trained language models (e.g., BERT, RoBERTa, and ALBERT), we demonstrate that MASKER improves OOD detection and cross-domain generalization without degrading classification accuracy. Code is available at https://github.com/alinlab/MASKER.Comment: AAAI 2021. First two authors contributed equall

Metal work-function-dependent barrier height of Ni contacts with metal-embedded nanoparticles to 4H-SiC

Metal, typically gold [Au], nanoparticles [NPs] embedded in a capping metal contact layer onto silicon carbide [SiC] are considered to have practical applications in changing the barrier height of the original contacts. Here, we demonstrate the use of silver [Ag] NPs to effectively lower the barrier height of the electrical contacts to 4H-SiC. It has been shown that the barrier height of the fabricated SiC diode structures (Ni with embedded Ag-NPs) has significantly reduced by 0.11 eV and 0.18 eV with respect to the samples with Au-NPs and the reference samples, respectively. The experimental results have also been compared with both an analytic model based on Tung's theory and physics-based two-dimensional numerical simulations

Age-related changes in cervical sagittal range of motion and alignment

Study Design Retrospective cohort study. Objective To compare sagittal cervical range of motion (ROM) and alignment in young versus middle-aged adults. Methods One hundred four asymptomatic adults were selected randomly out of 791 subjects who underwent lateral cervical radiographs in neutral, flexion, and extension positions. They were divided into two groups: young (age 20 to 29, 52 people) and middle-aged adults (age 50 to 59, 52 people). We determined the ROMs of upper cervical (occipital–C2 angle), midcervical (C2–C7 angle), and cervicothoracic spine (cervicosternal angle). We compared the alignment differences of the two groups by calculating the distances between C2 and C7 plumb lines, and C2 central-offset distance. Results In neutral position, there was no significant difference between young and middle-aged adults. However, in flexion, C2–C7 angle, distance between C2–C7 plumb lines, and C2 central-offset distance decreased with age. In extension, C2–C7 angle and C2 central-offset distance decreased with age. During flexion and extension, midcervical ROM and the range of C2 central-offset distance decreased in the middle-aged group. However, there was no difference between the two age groups in the ROM of the upper cervical and the cervicothoracic regions during flexion and extension. Conclusion We found that, despite of the presence of age-related cervical alignment changes, the only difference between the two groups was in the sagittal ROM of the midcervical spine during flexion and extension. Only the ROM of the midcervical spine appears to change significantly, consistent with findings that these levels are most likely to develop both symptomatic and asymptomatic degenerative changes

Fecal Microbiota Transplantation beyond Clostridioides Difficile Infection

With advancing analytical methods for gut microbes, many studies have been conducted, revealing that gut microbes cause various diseases, including gastrointestinal and non-gastrointestinal diseases. Accordingly, studies have been actively conducted to analyze the effects on the prevention and treatment of these diseases through changes in intestinal microbes and control of dysbiosis. Fecal microbiota transplantation (FMT) is an effort and is currently being applied to Clostridioides difficile treatment in Korea. Many studies have demonstrated the application of FMT in inflammatory bowel disease, irritable bowel syndrome, non-alcoholic fatty liver disease, metabolic syndrome, obesity, and diabetes. With further studies and accumulation of evidence, FMT could help treat presently untreatable diseases in clinical practice

PREVENTING SUBSTANCE ABUSE AMONG ADOLESCENTS: EVALUATION OF AN INTEGRATED MODEL COMBINING LIFE SKILLS TRANING AND PARENT TRANING

This study examines the effectiveness of an integrated model combining Life Skills Training (LST) for students and Love and Logic Training (LLT) for parents. 310 middle school students and 49 parents were participated in the study. A paired sample t-test was computed to compare pre and post-test scores for each participant. An independent sample t-test was used to determine if statistical differences exist between the treatment and control groups. Alcohol use and resistance to alcohol use among both treatment and control groups were significantly changed after the intervention in a positive way. No significant change in substance use was found in both groups. When it comes to comparison between treatment and control groups, a significant difference was found only in resistance to alcohol use, meaning participants in treatment group showed significantly higher level of resistance to alcohol use than control group after the intervention. Implications of these results for practice and training were discussed

Exploring valid reference genes for gene expression studies in Brachypodium distachyon by real-time PCR

<p>Abstract</p> <p>Background</p> <p>The wild grass species <it>Brachypodium distachyon </it>(Brachypodium hereafter) is emerging as a new model system for grass crop genomics research and biofuel grass biology. A draft nuclear genome sequence is expected to be publicly available in the near future; an explosion of gene expression studies will undoubtedly follow. Therefore, stable reference genes are necessary to normalize the gene expression data.</p> <p>Results</p> <p>A systematic exploration of suitable reference genes in Brachypodium is presented here. Nine reference gene candidates were chosen, and their gene sequences were obtained from the Brachypodium expressed sequence tag (EST) databases. Their expression levels were examined by quantitative real-time PCR (qRT-PCR) using 21 different Brachypodium plant samples, including those from different plant tissues and grown under various growth conditions. Effects of plant growth hormones were also visualized in the assays. The expression stability of the candidate genes was evaluated using two analysis software packages, geNorm and NormFinder. In conclusion, the ubiquitin-conjugating enzyme 18 gene (<it>UBC18</it>) was validated as a suitable reference gene across all the plant samples examined. While the expression of the polyubiquitin genes (<it>Ubi4 </it>and <it>Ubi10</it>) was most stable in different plant tissues and growth hormone-treated plant samples, the expression of the S-adenosylmethionine decarboxylase gene (<it>SamDC</it>) ranked was most stable in plants grown under various environmental stresses.</p> <p>Conclusion</p> <p>This study identified the reference genes that are most suitable for normalizing the gene expression data in Brachypodium. These reference genes will be particularly useful when stress-responsive genes are analyzed in order to produce transgenic plants that exhibit enhanced stress resistance.</p