Impurity scattering in a d-wave superconductor

The influence of (non-magnetic and magnetic) impurities on the transition temperature of a d-wave superconductor is studied anew within the framework of BCS theory. Pairing interaction decreases linearly with the impurity concentration. Accordingly $T_{c}$ suppression is proportional to the (potential or exchange) scattering rate, $1/\tau$, due to impurities. The initial slope versus $1/\tau$ is found to depend on the superconductor contrary to Abrikosov-Gor'kov type theory. Near the critical impurity concentration $T_{c}$ drops abruptly to zero. Because the potential scattering rate is generally much larger than the exchange scattering rate, magnetic impurities will also act as non-magnetic impurities as far as the $T_{c}$ decrease is concerned. The implication for the impurity doping effect in high $T_{c}$ superconductors is also discussed.Comment: 12 pages and 1 figure, PlainTex, submitted to Mod. Phys. Lett. B, For more information, please see "http://taesan.kaist.ac.kr/~yjkim

Simultaneous dual-frequency radio observations of S5 0716+714: A search for intraday variability with the Korean VLBI Network

This study aims to search for the existence of intraday variability (IDV) of BL Lac object S5 0716+714 at high radio frequencies for which the interstellar scintillation effect is not significant. Using the 21-meter radio telescope of the Korean VLBI Network (KVN), we present results of multi-epoch simultaneous dual-frequency radio observations. Single-dish observations of S5 0716+714 were simultaneously conducted at 21.7 GHz (K-band) and 42.4 GHz (Q-band), with a high cadence of 30-60 minute intervals.We observed four epochs between December 2009 and June 2010. Over the whole set of observation epochs, S5 0716+714 showed significant inter-month variations in flux density at both the K- and Q-bands, with modulation indices of approximately 19% for the K-band and approximately 36% for the Q-band. In all epochs, no clear intraday variability was detected at either frequency. The source shows monotonic flux density increase in epochs 1 and 3 and monotonic flux density decrease in epochs 2 and 4. In the flux density increasing phases, the flux densities at the Q-band increase more rapidly. In the decreasing phase, no significant flux density difference is seen at the two frequencies. The situation could be different close to flux density peaks that we did not witness in our observations. We find an inverted spectrum with mean spectral indices of -0.57+-0.13 in epoch 1 and -0.15+-0.11 in epoch 3. On the other hand, we find relatively steep indices of +0.24+-0.14 and +0.17+-0.18 in epochs 2 and 4, respectively. We conclude that the frequency dependence of the variability and the change of the spectral index are caused by source-intrinsic effects rather than by any extrinsic scintillation effect.Comment: 6 pages and 4 figures and 4 table

Gastric extremely well differentiated adenocarcinoma of gastric phenotype: as a gastric counterpart of adenoma malignum of the uterine cervix

BACKGROUND: Most of gastric adenocarcinoma can be simply diagnosed by microscopic examination of biopsy specimen. Rarely the structural and cellular atypia of tumor cells is too insignificant to discriminate from benign foveolar epithelium. CASE PRESENTATION: A 67-year-old male presented with a gastric mass incidentally found on the abdominal computed tomography (CT) for routine medical examination. Gastric endoscopic examination revealed a huge fungating mass at the cardia and mucosal biopsy was performed. Microscopically the biopsy specimen showed proliferation of bland looking foveolar epithelia in the inflammatory background and diagnosed as foveolar epithelial hyperplasia. Because the clinical and endoscopic features of this patient were strongly suggestive of malignancy, the patient underwent radical total gastrectomy. The resected stomach revealed a huge fungating tumor at the cardia. The cut surface of the tumor was whitish gelatinous. Microscopically the tumor was sharply demarcated from surrounding mucosa and composed of very well formed glandular structures without significant cellular atypia, which invaded into the whole layer of the gastric wall. Tumor glands were occasionally complicated or dilated, and glandular lumina were filled with abundant mucin. Immunohistochemically the tumor cells revealed no overexpression of p53 protein but high Ki-67 labeling index. The tumor cells and intraluminal mucin were diffusely expressed MUC1 and MUC5AC and only focally expressed MUC2. On abdominal CT taken after 12 months demonstrated peritoneal carcinomatosis and multiple metastatic foci in the lung. CONCLUSION: The clinicopathologic profiles of gastric extremely well differentiated adenocarcinoma of gastric phenotype include cardiac location, fungating gross type, very similar histology to foveolar epithelial hyperplasia, foveolar mucin phenotype, lack of p53 overexpressoin and high proliferative index

The New Zombie Apocalypse and Social Crisis in South Korean Cinema

The popular culture version of the zombie, developed over the latter half of the twentieth century, made only sporadic appearances in South Korean film, which may in part be attributed to the restrictions on the distribution of American and Japanese films before 1988. Thus the first zombie film Monstrous Corpse (Goeshi 1980, directed by Gang Beom-Gu), was a loose remake of the Spanish-Italian Non si deve profanare il sonno dei morti (1974). Monstrous Corpse was largely forgotten until given a screening by KBS in 2011. Zombies don’t appear again for a quarter of a century. This article examines four zombie films released between 2012 and 2018: “Ambulance”, the fourth film in Horror Stories (2012), a popular horror portmanteau film; Train to Busan (2016) (directed by Yeon Sang-Ho), the first South Korean blockbuster film in the “zombie apocalypse” sub-genre; Seoul Station (2016), an animation prequel to Train to Busan (also directed by Yeon Sang-Ho); and Rampant (2018, directed by Kim Seong-Hun ), a costume drama set in Korea’s Joseon era. Based on a cognitive studies approach, this article examines two conceptual metaphors which underlie these films: the very common metaphor, LIFE IS A JOURNEY, and the endemically Korean metaphor THE NATION IS A FAMILY

F-saturation games

This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.disc.2015.05.028We study F-saturation games, first introduced by Füredi, Reimer and Seress [4] in 1991, and named as such by West [5]. The main question is to determine the length of the game whilst avoiding various classes of graph, playing on a large complete graph. We show lower bounds on the length of path-avoiding games, and more precise results for short paths. We show sharp results for the tree avoiding game and the star avoiding game.The first author was supported by Trinity College, Cambridge. The second author was partially supported by the Estonian Research Council through the research grants PUT405, PUT620 and IUT20-5

Rigidity of silicone substrates controls cell spreading and stem cell differentiation.

The dependences of spreading and differentiation of stem cells plated on hydrogel and silicone gel substrates on the rigidity and porosity of the substrates have recently been a subject of some controversy. In experiments on human mesenchymal stem cells plated on soft, medium rigidity, and hard silicone gels we show that harder gels are more osteogenic, softer gels are more adipogenic, and cell spreading areas increase with the silicone gel substrate rigidity. The results of our study indicate that substrate rigidity induces some universal cellular responses independently of the porosity or topography of the substrate

A Personalized Recommender System Based on Explanation Facilities Using Collaborative Filtering

Collaborative filtering (CF) is the most successful recommendation method, but its widespread use has exposed some limitations, such as sparsity, scalability, and black box. Many researchers have focused on sparsity and scalability problem but a little has tried to solve the black box problem. Most CF recommender systems are black boxes, providing no transparency into the working of the recommendation. This research suggests an improved CF recommender system with explanation facilities to overcome the black box problem. Explanation facilities make it possible to expose the reasoning and data behind a recommendation. Therefore, explanations provide us with a mechanism for handling errors that come with a recommendation. Furthermore, it is proposed to use web usage mining and product taxonomy to enhance the recommendation quality for e-commerce environment. For such purposes, it is developed a recommender system named WebCF-Exp, Web usage mining driven Collaborative Filtering with Explanation facilities. To test the performance of WebCF-Exp, EBIB research internet shopping mall and explanation interfaces are developed. Experiments are conducted with the data provided by EBIB Research Internet shopping mall

How Media and Behavioral Characteristics of Mobile Instant Messenger Affact Intimacy and Fatigue? The Moderating Effect of The Communication Context

Mobile instant messenger has become a part of our daily life because a smartphone is the primary communication device. To communicate other friends, they use a mobile instant messenger more frequently than giving a phone call. This study aims to investigate why people communicate others through a mobile instant messenger based on media and behavioral characteristics, which affect intimacy and fatigue. We expect this study would contribute for understanding the communication with a mobile instant messenger

Work-related correlates of occupational sitting in a diverse sample of employees in Midwest metropolitan cities

The worksite serves as an ideal setting to reduce sedentary time. Yet little research has focused on occupational sitting, and few have considered factors beyond the personal or socio-demographic level. The current study i) examined variation in occupational sitting across different occupations, ii) explored whether worksite level factors (e.g., employer size, worksite supports and policies) may be associated with occupational sitting. Between 2012 and 2013, participants residing in four Missouri metropolitan areas were interviewed via telephone and provided information on socio-demographic characteristics, schedule flexibility, occupation, work related factors, and worksite supports and policies. Occupational sitting was self-reported (daily minutes spent sitting at work), and dichotomized. Occupation-stratified analyses were conducted to identify correlates of occupational sitting using multiple logistic regressions. A total of 1668 participants provided completed data. Those employed in business and office/administrative support spent more daily occupational sitting time (median 330 min) compared to service and blue collar employees (median 30 min). Few worksite supports and policies were sitting specific, yet factors such as having a full-time job, larger employer size, schedule flexibility, and stair prompt signage were associated with occupational sitting. For example, larger employer size was associated with higher occupational sitting in health care, education/professional, and service occupations. Work-related factors, worksite supports and policies are associated with occupational sitting. The pattern of association varies among different occupation groups. This exploratory work adds to the body of research on worksite level correlates of occupational sitting. This may provide information on priority venues for targeting highly sedentary occupation groups