Different Behavior of Magnetic Impurities in Crystalline and Ammorphous States of Superconductors

It has been observed that the effect of magnetic impurities in a superconductor is drastically different depending on whether the host superconductor is in a crystalline or an amorphous state. Based on the recent theory of Kim and Overhauser (KO), it is shown that as the system is getting disordered, the initial slope of the $T_{c}$ depression is decreasing by a factor $\sqrt{\ell/\xi_{0}}$, when the mean free path $\ell$ becomes smaller than the BCS coherence length $\xi_{0}$, which is in agreement with experimental findings. In addition, for a superconductor in a crystalline state in the presence of magnetic impurities the superconducting transition temperature $T_{c}$ drops sharply from about 50% of $T_{c0}$ (for a pure system) to zero near the critical impurity concentration. This {\sl pure limit behavior} was indeed found by Roden and Zimmermeyer in crystalline Cd. Recently, Porto and Parpia have also found the same {\sl pure limit behavior} in superfluid He-3 in aerogel, which may be understood within the framework of the KO theory.Comment: 7 figures, 20 pages, latex, to appear in Superconductor Science and Technolog

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

Health information behavior in families: Supportive or irritating?

We report preliminary results of a mixed methods study of relationships between family‐based information behavior and social support in chronic illness. Twenty‐four participants (12 people with HIV/AIDS (PHAs) and 12 people with diabetes) completed surveys, visualized their family‐based social support networks, and participated in in‐depth, qualitative interviews. Findings revealed that our sample of people with diabetes had significantly larger family support networks than did PHAs. These differences seem linked to greater interpersonal constraints in talking about HIV/AIDS in families. Yet, the two groups did not differ in terms of perceived social support (PSS), frequency of collaborative information behavior (CIB), or use of information obtained collaboratively. However, a surprising relationship between CIB and PSS emerged among diabetics but not PHAs: the greater the frequency of CIB with family members, the less supportive they were perceived to be. This seems rooted in the prevalence of attempted influence and interference by diabetics' family members. Nevertheless, among both PHAs and diabetics, a significant overlap existed between receipt of informational and emotional support. Indeed, information sharing and emotional support could be the same in interactions such as questions of concern, goal attainment, and caring forwards. This study is among the first to document differences in social support and CIB among people with different diseases, pointing to the merit of information services and systems differentiated by disease. The overlap between informational and emotional support suggests the value of organizing, presenting, or rating health information according to emotional valence. Demonstrating that CIB may have negative effects challenges information scientists to reconsider whether receipt of information is always positive. Health information behavior in families therefore appears more complex than has been previously shown.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90033/1/14504801070_ftp.pd

How content contributors assess and establish credibility on the web

The proliferation of user‐generated content (UGC) is one of the distinguishing characteristics of Web 2.0. Internet users contribute content online through platforms such as blogs, wikis, video sharing sites, and sites that allow user feedback. Yet little is known of the credibility practices of these content contributors. Through phone interviews conducted with 29 online content contributors, this study investigates how content contributors assess credibility when gathering information for their online content creation and mediation activities, as well as the strategies they use to establish the credibility of the content they create. These contributors reported that they engaged in content creation activities such as posting or commenting on blogs or online forums, rating or voting on online content, and uploading photos, music, or video. We found that credibility judgments made when gathering information for online content creation and mediation activities could be grouped into three levels: intuitive, heuristic, and strategy‐based. We identified three distinctive ways of establishing credibility that are applied during different phases of content contribution: ensuring credibility during the content creation phase; signaling credibility during the content presentation phase; and reinforcing credibility during the post‐production phase. We also discovered that content contributors tend to carry over the strategies they used for assessing credibility during information gathering to their strategies for establishing the credibility of their own content. Theoretical implications for credibility research and practical implications for developing information literacy programs are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90253/1/14504801163_ftp.pd

An investigation of the effects of IT investment on firm performance: The role of complementarity.

The concept of complementarity has been introduced into IT-based firm performance research in order to address inconsistent magnitudes of the impacts from IT investments across studies. This dissertation seeks to understand the scope of IT investment complementarities, to examine the different ways in which different complementarities impact the payoff from an IT investment, and to empirically test the effects of complementary investments in the context of investments in SCM and CRM. The knowledge-based view of the firm (KBV) is employed in order to understand a boundary and different roles of complementarity. The KBV sees organizational capabilities from the aggregation of knowledge into capabilities and the deployment of knowledge assets in the form of capabilities. Knowledge aggregation requires individuals' specialized knowledge (human capital) and the aggregation mechanisms of structural, social, and community capital. The combination of these three forms of capital, together with human capital, constitutes organizational capabilities. Once constituted, the complementary deployment of capabilities is important. Foundational capability must be in place in order for the focal IT investment to deliver value, synergistic capability amplifies the economic benefits of the focal IT investment, and management capability is managers' organizing vision and capability to successfully deploy the focal IT investment.The research findings show that three forms of structural, community, and human capital have highly significant impacts on firm performance measured by Net Cash Flow, Gross Profit, and EBITDA. Synergistic capabilities and management capabilities are found to be highly significant in moderating between three forms of capital and firm performance measurements.The data for this study were drawn from secondary data sources: Annual Reports, Press Releases, and news articles. The dependent variables are drawn from COMPUSTAT. The data collection method for the independent variables was a keyword search. The research sampling frame is confined within a single value chain however distinctively different industry categories are represented within this value chain. This sampling strategy yielded a total of 111 firms that had invested in SCM and 45 firms that had invested in CRM

The role of tags in information retrieval interaction

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63044/1/14504503137_ftp.pd

Molecular genetic study of novel biomarkers for early diagnosis of oral squamous cell carcinoma

Objectives: Early detection and treatment of an oral squamous cell carcinoma (OSCC) is critical because of its rapid growth, frequent lymph-node metastasis, and poor prognosis. However, no clinically-valuable methods of early diagnosis exist, and genetic analysis of OSCCs has yielded no biomarkers. Study D esign: We investigated the expression of genes associated with inflammation in OSCCs via a quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) analysis of microarray data. Tumor and normal tissues from five patients with an OSCC were used for microarray analysis. Differentially-expressed genes, identified using permutation, local pooled error (LPE), t-tests, and significance analysis of microarrays (SAM), were selected as candidate genetic markers. Results: Two groups corresponding to tissue identity were evident, implying that their differentially-expressed genes represented biological differences between tissues. Fifteen genes were identified using the Student’s paired t-test ( p< 0.05) and the SAM, with a false discovery rate of less than 0.02. Based on gene expression, these 15 genes can be used to classify an OSCC. A genetic analysis of functional networks and ontologies, validated by using a qRT-PCR analysis of the tissue samples, identified four genes, ADAM15, CDC7, IL12RB2 and TNFRSF8, that demonstrated excellent concordance with the microarray data. Conclusions: Our study demonstrated that four genes (ADAM15, CDC7, IL12RB2 and TNFRSF8) had potential as novel biomarkers for the diagnosis and the treatment of an OSCC