Dynamical complexity in the perception-based network formation model

Many link formation mechanisms for the evolution of social networks have been successful to reproduce various empirical findings in social networks. However, they have largely ignored the fact that individuals make decisions on whether to create links to other individuals based on cost and benefit of linking, and the fact that individuals may use perception of the network in their decision making. In this paper, we study the evolution of social networks in terms of perception-based strategic link formation. Here each individual has her own perception of the actual network, and uses it to decide whether to create a link to another individual. An individual with the least perception accuracy can benefit from updating her perception using that of the most accurate individual via a new link. This benefit is compared to the cost of linking in decision making. Once a new link is created, it affects the accuracies of other individuals' perceptions, leading to a further evolution of the actual network. As for initial actual networks, we consider homogeneous and heterogeneous cases. The homogeneous initial actual network is modeled by Erd\H{o}s-R\'enyi (ER) random networks, while we take a star network for the heterogeneous case. In any cases, individual perceptions of the actual network are modeled by ER random networks with controllable linking probability. Then the stable link density of the actual network is found to show discontinuous transitions or jumps according to the cost of linking. As the number of jumps is the consequence of the dynamical complexity, we discuss the effect of initial conditions on the number of jumps to find that the dynamical complexity strongly depends on how much individuals initially overestimate or underestimate the link density of the actual network. For the heterogeneous case, the role of the highly connected individual as an information spreader is discussed.Comment: 8 pages, 7 figure

Coevolution of a network and perception

How does an individual's cognition change a system which is a collective behavior of individuals? Or, how does a system affect an individual's cognition? To examine the interplay between a system and individuals, we study a cognition-based network formation. When a network is not fully observable, individuals' perception of a network plays an important role in decision making. Assuming that a communication link is costly, and more accurate perception yields higher network utility, an agent decides whether to form a link in order to get better information or not. Changes in a network with newly added links affect individuals' perception accuracy, which may cause further changes in a network. We characterize the early stage of network dynamics and information dispersion. Network structures in a steady state are also examined. Additionally, we discuss local interactions and a link concentration in a frequently changing network.Comment: 32 pages, 8 figure

Episodic Peripheral Contributors and Technical Dependencies in Open Source Software (OSS) Ecosystems

Despite the fact that OSS contributors tend to eschew traditional organizational hierarchies, researchers have found that, in many cases, OSS contributors make tightly coupled system designs and successfully coordinate highly interdependent tasks. Although researchers have explained how OSS contributors make tightly coupled code contributions, we do not know the characteristics of individuals who make such contributions. While previous studies have considered OSS projects as single, independent containers, I note that OSS projects do not constitute independent or standalone entities but reuse and, thus, depend one another. This reuse creates complex networks of interdependencies called “software ecosystems”. In this paper, I analyze OSS contributors who have made tightly coupled code contributions using two lenses: the core-periphery lens and the habitual-episodic lens. Based on investigating three volunteer-driven OSS projects, I found OSS contributors who make tightly coupled code contributions to have different code-contribution patterns. Interestingly, I found that half of such contributors made no previous code contributions to the sampled projects but episodically authored patches (or pull requests) that increased software coupling. Based on further investigation, I suggest a multiple-fluid-container view that accommodates software ecosystems in which multiple containers (multiple OSS projects) co-evolve with each container (each OSS project) readily accessible

Gender and quality at top economics journals

We show articles published in “top-five” economics journals authored by men are cited less than articles those same journals publish by women. Additionally, men’s citations rise when they co-author with women whereas women’s citations fall while they co-author with men, conditional on acceptance. Under strong—but we believe reasonable—assumptions, our findings imply top economics journals hold female-authored papers to higher standards and, as a result, do not publish the highest quality research. They also suggest that authors will be less willing to collaborate with women, all else equal

X-ray crystal structure, UV–Vis and NMR spectroscopic, and molecular docking studies of pyribencarb isomers

The crystal structures of the pyribencarb E and Z stereoisomers were determined using single-crystal X-ray crystallography. The isomers were confirmed a single data respectively by crystal analysis, LC-UVD mass spectrometry, and NMR spectroscopy. Pyribencarb E crystallizes in triclinic P−1 and the Z isomer in monoclinic P21/c, with the crystal structures showing comparable packing motifs. Moreover, molecular docking was carried out with cytochrome bc1, revealing binding energies in the ranges of −24.9 to −17.6 and −21.6 to −14.7kcal/mol for the E and Z isomers, respectively. Through a combined experimental and theoretical approach, this study contributes to our understanding of pesticides. Graphical Abstrac

Orthodenticle homeobox 2 is transported to lysosomes by nuclear budding vesicles

Transcription factors (TFs) are transported from the cytoplasm to the nucleus and disappear from the nucleus after they regulate gene expression. Here, we discover an unconventional nuclear export of the TF, orthodenticle homeobox 2 (OTX2), in nuclear budding vesicles, which transport OTX2 to the lysosome. We further find that torsin1a (Tor1a) is responsible for scission of the inner nuclear vesicle, which captures OTX2 using the LINC complex. Consistent with this, in cells expressing an ATPase-inactive Tor1aΔE mutant and the LINC (linker of nucleoskeleton and cytoskeleton) breaker KASH2, OTX2 accumulated and formed aggregates in the nucleus. Consequently, in the mice expressing Tor1aΔE and KASH2, OTX2 could not be secreted from the choroid plexus for transfer to the visual cortex, leading to failed development of parvalbumin neurons and reduced visual acuity. Together, our results suggest that unconventional nuclear egress and secretion of OTX2 are necessary not only to induce functional changes in recipient cells but also to prevent aggregation in donor cells

21st Century Information Workers: What Core Competencies Should MSIS Students Learn?

The day-to-day work of information workers charged with information creation, organization, presentation, preservation, analysis, and retrieval is changing dramatically because of rapid advances in technology, the ubiquitous availability of information, and the increasing diversity and globalization of users, patrons, and co-workers. Further, the jobs themselves are changing, such that information workers are not likely to focus on one traditional information task, but must integrate other knowledge and skills, such as data analysis (with large data) and social media. The array of jobs and tasks leads us to ask: what are the core competencies for all information studies students? The authors conducted a survey of more than 2,000 information professionals focusing on six information work roles (archivy, data analysis, librarianship, records/digital assets management, social media, and user experience) to find out about their day-to-day work and their recommendations for formal curriculum. In this special session, we will organize a lively discussion debating professionals’ conflicting recommendations for formal iSchool curriculum.ye

Limitations of Conventional Contrast-enhanced MRI in Selecting Sentinel Node Biopsy Candidates among DCIS Patients

Purpose: A better predictive model for occult invasive disease in ductal carcinoma in situ (DCIS) patients is essential to guide the tailored use of sentinel node biopsies. We hypothesized that recent improvement of contrast-enhanced breast magnetic resonance imaging (MRI) could provide more accurate information on the presence of occult invasion in DCIS patients. Methods: From a prospectively maintained database, we identified 143 DCIS patients diagnosed with needle biopsies in whom MRI images were available. Results: Sixty-five patients (45.5%) were upstaged to invasive carcinoma after curative surgery. Ultrasonographic lesion size, mass-appearance on mammography, type of needle used, and the presence of suspicious microinvasive foci were associated with increased likelihood of upstaging. Among the features of MRI, only mass-appearance was significantly associated with the presence of invasive disease (p=0.002). However, up to 50% of masses in MRI cases had mass-appearance on mammography as well. Other morphologic and pharmacokinetic features of MRI, such as shape, margin, and patterns of enhancement and washout, did not have a significant association. Conclusion: Among various morphologic and pharmacokinetic parameters of contrast-enhanced MRI, only mass-appearance was associated with occult invasive disease. Our results show the limitations of current contrast-enhanced MRI in predicting invasive disease in patients with preoperative diagnoses of DCIS.Moon HG, 2009, ANN ONCOL, V20, P636, DOI 10.1093/annonc/mdn683Kuerer HM, 2009, J CLIN ONCOL, V27, P279, DOI 10.1200/JCO.2008.18.3103HU M, 2009, P NATL ACAD SCI USA, V106, P3372Gadre SA, 2008, HISTOPATHOLOGY, V53, P545, DOI 10.1111/j.1365-2559.2008.03152.xOkumura Y, 2008, BMC CANCER, V8, DOI 10.1186/1471-2407-8-287Sakorafas GH, 2008, CANCER TREAT REV, V34, P483, DOI 10.1016/j.ctrv.2008.03.001Morrow M, 2008, ANN SURG ONCOL, V15, P2641, DOI 10.1245/s10434-008-0083-zPorembka MR, 2008, ANN SURG ONCOL, V15, P2709, DOI 10.1245/s10434-008-9947-5Lee JW, 2008, J SURG ONCOL, V98, P15, DOI 10.1002/jso.21077Hu M, 2008, CANCER CELL, V13, P394, DOI 10.1016/j.ccr.2008.03.007Ansari B, 2008, BRIT J SURG, V95, P547, DOI 10.1002/bjs.6162Orel S, 2008, J CLIN ONCOL, V26, P703, DOI 10.1200/JCO.2007.14.3594Facius M, 2007, CLIN IMAG, V31, P394, DOI 10.1016/j.clinimag.2007.04.030Kuhl CK, 2007, LANCET, V370, P485Jung EJ, 2007, INT J CANCER, V120, P2331, DOI 10.1002/ijc.22434Nielsen BS, 2007, INT J CANCER, V120, P2086, DOI 10.1002/ijc.22340van der Velden APS, 2006, AM J SURG, V192, P172, DOI 10.1016/j.amjsurg.2006.02.026Goyal A, 2006, BREAST CANCER RES TR, V98, P311, DOI 10.1007/s10549-006-9167-2Mansel RE, 2006, J NATL CANCER I, V98, P599, DOI 10.1093/jnci/djj158Lyman GH, 2005, J CLIN ONCOL, V23, P7703, DOI 10.1200/JCO.2005.08.001Wilkie C, 2005, AM J SURG, V190, P563, DOI 10.1016/j.amjsurg.2005.06.011Groves AM, 2005, MAGN RESON IMAGING, V23, P733, DOI 10.1016/j.mri.2005.06.003Hylton N, 2005, J CLIN ONCOL, V23, P1678, DOI 10.1200/JCO.2005.12.002Leonard GD, 2004, J NATL CANCER I, V96, P906, DOI 10.1093/jnci/djh164Hata T, 2004, J AM COLL SURGEONS, V198, P190, DOI 10.1016/j.jamcollsurg.2003.10.008Hwang EW, 2003, ANN SURG ONCOL, V10, P381, DOI 10.1245/ASO.2003.03.085*AM COLL RAD, 2003, ACR BI RADS BREAST IMorrow M, 2002, CA-CANCER J CLIN, V52, P277Jackman RJ, 2001, RADIOLOGY, V218, P497Brown LF, 1999, CLIN CANCER RES, V5, P1041