398 research outputs found
Genetic attack on neural cryptography
Different scaling properties for the complexity of bidirectional
synchronization and unidirectional learning are essential for the security of
neural cryptography. Incrementing the synaptic depth of the networks increases
the synchronization time only polynomially, but the success of the geometric
attack is reduced exponentially and it clearly fails in the limit of infinite
synaptic depth. This method is improved by adding a genetic algorithm, which
selects the fittest neural networks. The probability of a successful genetic
attack is calculated for different model parameters using numerical
simulations. The results show that scaling laws observed in the case of other
attacks hold for the improved algorithm, too. The number of networks needed for
an effective attack grows exponentially with increasing synaptic depth. In
addition, finite-size effects caused by Hebbian and anti-Hebbian learning are
analyzed. These learning rules converge to the random walk rule if the synaptic
depth is small compared to the square root of the system size.Comment: 8 pages, 12 figures; section 5 amended, typos correcte
Convergence Radii for Eigenvalues of Tri--diagonal Matrices
Consider a family of infinite tri--diagonal matrices of the form
where the matrix is diagonal with entries and the matrix
is off--diagonal, with nonzero entries The spectrum of is discrete. For small the
-th eigenvalue is a well--defined analytic
function. Let be the convergence radius of its Taylor's series about It is proved that R_n \leq C(\alpha) n^{2-\alpha} \quad \text{if} 0 \leq
\alpha <11/6.$
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Journalism in a globalized risk arena: Between networks, interdependencies and power relations
Realignment-enhanced coherent anti-Stokes Raman scattering (CARS) and three-dimensional imaging in anisotropic fluids
We apply coherent anti-Stokes Raman Scattering (CARS) microscopy to
characterize director structures in liquid crystals.Comment: 14 pages, 11 figure
Socially sensitive lactation: Exploring the social context of breastfeeding
Many women report difficulties with breastfeeding and do not maintain the practice for as long as intended. Although psychologists and other researchers have explored some of the difficulties they experience, fuller exploration of the relational contexts in which breastfeeding takes place is warranted to enable more in-depth analysis of the challenges these pose for breastfeeding women. The present paper is based on qualitative data collected from 22 first-time breastfeeding mothers through two phases of interviews and audio-diaries which explored how the participants experienced their relationships with significant others and the wider social context of breastfeeding in the first five weeks postpartum. Using a thematic analysis informed by symbolic interactionism, we develop the overarching theme of âPractising socially sensitive lactationâ which captures how participants felt the need to manage tensions between breastfeeding and their perceptions of the needs, expectations and comfort of others. We argue that breastfeeding remains a problematic social act, despite its agreed importance for child health. Whilst acknowledging the limitations of our sample and analytic approach, we suggest ways in which perinatal and public health interventions can take more effective account of the social challenges of breastfeeding in order to facilitate the health and psychological well-being of mothers and their infants
International journalism and the emergence of transnational publics: between cosmopolitan norms, the affirmation of identity and market forces
Much has been written about transnational public spheres, though our understanding of their shape and nature remains limited. Drawing on three alternative conceptions of newswork as public communication, this article explores the role of international journalists in shaping transnational publics. Based on a series of original interviews, it asks how journalists are oriented in their newswork (e.g. are they cosmopolitan or parochial in their orientation) and how they âimagineâ the public. It finds that interviewees imagine a polycentric transnational public and variously frame their work as giving voice to those affected by an issue (imagining the public as a cosmopolitan community of fate), performing and reaffirming a particular kind of identity and belonging (imagining the public as a nation) or pursuing audiences wherever they may be (imagining the public as the de facto audience)
Development of a Multiphoton Fluorescence Lifetime Imaging Microscopy (FLIM) system using a Streak Camera
We report the development and detailed calibration of a multiphoton
fluorescence lifetime imaging system (FLIM) using a streak camera. The present
system is versatile with high spatial (0.2 micron) and temporal (50 psec)
resolution and allows rapid data acquisition and reliable and reproducible
lifetime determinations. The system was calibrated with standard fluorescent
dyes and the lifetime values obtained were in very good agreement with values
reported in literature for these dyes. We also demonstrate the applicability of
the system to FLIM studies in cellular specimens including stained pollen
grains and fibroblast cells expressing green fluorescent protein. The lifetime
values obtained matched well with those reported earlier by other groups for
these same specimens. Potential applications of the present system include the
measurement of intracellular physiology and Fluorescence Resonance Energy
Transfer (FRET) imaging which are discussed in the context of live cell
imaging
Conceptualizing a distributed, multi-scalar global public sphere through activist communication practices in the World Social Forum
This article contributes to debate about how to conceptualize the global public sphere. Drawing on media practice theory and ethnographic research on media activism in the World Social Forum, it shows how âglobal publicsâ can be constituted through a diverse range of activist communication practices that complicate both conventional hierarchies of scale and contemporary theorizations of publics as personalized networks. It develops an understanding of the global public sphere as an emergent formation made up of multiple, interlinked publics at different scales and emphasizes the significance of collective communication spaces for actors at the margins of the global network society
Localization of hRad9 in breast cancer
<p>Abstract</p> <p>Background</p> <p><it>hRad9 </it>is a cell cycle checkpoint gene that is up-regulated in breast cancer. We have previously shown that the mRNA up-regulation correlated with tumor size and local recurrence. Immunohistochemical studies were made to better define the role of <it>hRad9 </it>in breast carcinogenesis.</p> <p>Methods</p> <p>Localisation of hRad9 protein were performed on paired tumor and normal breast tissues. Immunoblotting with and without dephosphorylation was used to define the protein isolated from breast cancer cells.</p> <p>Results</p> <p>Increased hRad9 protein was observed in breast cancer cells nucleus compared to non-tumor epithelium. This nuclear protein existed in hyperphosphorylated forms which may be those of the hRad9-hRad1-hHus1 complex.</p> <p>Conclusion</p> <p>Finding of hyperphosphorylated forms of hRad9 in the nucleus of cancer cells is in keeping with its function in ameliorating DNA instability, whereby it inadvertently assists tumor growth.</p
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