6,583 research outputs found
Preach wine and serve vinegar: Public relations, relationships and doublethink
This article argues that organization-public relationships (OPR) generate challenges for PR as both a practical and theoretical discipline. The investigation is set against the backdrop of the growing pre-occupation with OPR in research and practice. The study highlights disconnections between how the field represents itself in an OPR context and the existence of particular attitudes and practices in each of these areas. It uses the Orwellian concept of doublethink as a conceptual device to tease out these tensions. These contradictions are framed as public relations doublethink and presented as critical propositions designed to illustrate the gaps that can exist between representation and reality. The article also debates the implications of these examples for the practical and theoretical development of public relations using research that considers how organizations listen to stakeholders on-line. It seeks to stimulate further debate through a new conceptualization of social media listening, as well as a set of inter-disciplinary insights concerned with the study of complex phenomenon. © 2014
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BRCA1 and CtIP suppress long tract gene conversion between sister chromatids
BRCA1 controls early steps of the synthesis-dependent strand annealing (SDSA) pathway of homologous recombination, but has no known role following Rad51-mediated synapsis. Here we show that BRCA1 influences post-synaptic homologous recombination events, controlling the balance between short- (STGC) and long-tract gene conversion (LTGC) between sister chromatids. Brca1 mutant cells reveal a bias towards LTGC that is corrected by expression of wild type but not cancer-predisposing BRCA1 alleles. The LTGC bias is enhanced by depletion of CtIP but reversed by inhibition of 53BP1, implicating DNA end resection as a contributor to the STGC/LTGC balance. The impact of BRCA1/CtIP loss on the STGC/LTGC balance is abolished when the second (non-invading) end of the break is unable to support termination of STGC by homologous pairing (“annealing”). This suggests that BRCA1/CtIP-mediated processing of the second end of the break controls the annealing step that normally terminates SDSA, thereby suppressing the error-prone LTGC outcome
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BRCA1 controls homologous recombination at Tus/Ter-stalled mammalian replication forks
Replication fork stalling can promote genomic instability, predisposing to cancer and other diseases1–3. Stalled replication forks may be processed by sister chromatid recombination (SCR), generating error-free or error-prone homologous recombination (HR) outcomes4–8. In mammalian cells, a long-standing hypothesis proposes that the major hereditary breast/ovarian cancer predisposition gene products, BRCA1 and BRCA2, control HR/SCR at stalled replication forks9. Although BRCA1 and BRCA2 affect replication fork processing10–12, direct evidence that BRCA genes regulate HR at stalled chromosomal replication forks is lacking due to a dearth of tools for studying this process. We report that the Escherichia coli Tus/Ter complex13–16 can be engineered to induce site-specific replication fork stalling and chromosomal HR/SCR in mammalian cells. Tus/Ter-induced HR entails processing of bidirectionally arrested forks. We find that the BRCA1 C-terminal tandem BRCT repeat and regions of BRCA1 encoded by exon 11—two BRCA1 elements implicated in tumor suppression—control Tus/Ter-induced HR. Inactivation of either BRCA1 or BRCA2 increases the absolute frequency of “long-tract” gene conversions at Tus/Ter-stalled forks—an outcome not observed in response to a restriction endonuclease-mediated chromosomal double strand break (DSB). Therefore, HR at stalled forks is regulated differently from HR at DSBs arising independently of a fork. We propose that aberrant long-tract HR at stalled replication forks contributes to genomic instability and breast/ovarian cancer predisposition in BRCA mutant cells
Semi-classical States in Homogeneous Loop Quantum Cosmology
Semi-classical states in homogeneous loop quantum cosmology (LQC) are
constructed by two different ways. In the first approach, we firstly construct
an exponentiated annihilation operator. Then a kind of semi-classical
(coherent) state is obtained by solving the eigen-equation of that operator.
Moreover, we use these coherent states to analyze the semi-classical limit of
the quantum dynamics. It turns out that the Hamiltonian constraint operator
employed currently in homogeneous LQC has correct classical limit with respect
to the coherent states. In the second approach, the other kind of
semi-classical state is derived from the mathematical construction of coherent
states for compact Lie groups due to Hall.Comment: 13 pages, submitted to CQ
One-Step Approach to Single-Ensemble CdS Magic-Size Clusters with Enhanced Production Yields
We report on the
development of a single-step method for synthesizing
colloidal semiconductor magic-size clusters (MSCs) with an enhanced
production yield in a single-ensemble form and free of the coproduction
of conventional quantum dots (QDs). This process eliminates the need
for the second step of a lower-temperature incubation used in a two-step
approach reported recently for the fabrication of single-ensemble
MSCs without QD contamination. We demonstrate that the combined use
of a secondary phosphine (HPR<sub>2</sub>) and an α-methyl carboxylic
acid [RCH(CH<sub>3</sub>)-COOH, MA] promotes the yield of MSCs and
suppresses the nucleation and growth of QDs. With CdO and elemental
S powder as Cd and S sources, respectively, a single ensemble of CdS
MSC-311 (displaying a sharp absorption peak at 311 nm) evolves directly
in a reaction in 1-octadecene with an enhanced production yield. This
study introduces a one-step avenue for synthesizing effectively and
selectively single-ensemble MSCs and improves our understanding of
the two-pathway model proposed for the prenucleation stage of QDs
Pengaruh Fraksi Penipisan (P) Air Tanah Tersedia Pada Berbagai Fase Tumbuh Terhadap Pertumbuhan, Hasil Dan Efisiensi Penggunaan Air Tanaman Kedelai (Glycine Max [L] Merr.)
Penelitian bertujuan untuk mengetahui pengaruh fraksi penipisan (p) air tanah tersedia pada berbagai fase tumbuh terhadap pertumbuhan dan efisiensi penggunaan air tanaman kedelai. Penelitian ini dilaksanakan di dalam rumah plastik, laboratorium lapang terpadu, Universitas Lampung pada bulan Oktober 2015 sampai dengan Januari 2016. Penelitian ini menggunakan rancangan Faktorial dalam Acak Lengkap (RAL) dengan 2 faktor perlakuan, yaitu faktor I (Fraksi penipisan air tanah tersedia, p) dan faktor II (fase tumbuh, F). Masing-masing perlakuan terdiri dari 3 taraf, yaitu faktor I terdiri dari P1(0,2), P2(0,4) dan P3(0,6) dari penipisan air tanah tersedia, dan faktor II terdiri dari fase vegetatif aktif (F1), fase pembungaan (F2), dan fase pembentukan polong (F3), dengan ulangan sebanyak 3 kali. Pengukuran evapotranspirasi tanaman acuan dilakukan pada fraksi penipisan 0,2 dari air tanah tersedia dengan menggunakan tanaman rumput. Hasil penelitian menunjukkan bahwa, perlakuan fraksi penipisan (p) air tanah tersedia pada berbagai fase tumbuhtidak berpengaruh terhadap pertumbuhan dan efisiensi penggunaan air tanaman kedelai.Tanaman kedelai pada perlakuan fraksi penipisan (p) air tanah tersedia tidak mengalami cekaman air pada semua perlakuan, karena tanaman sebelum mendekati batas bawah perlakuan segera diberi irigasi dan dikembalikan ke kondisi kapasitas lapang. Produksi tertinggi dengan nilai efisiensi penggunaan air tertinggi dicapai oleh perlakuan fraksi penipisan (0-0,2) air tanah tersedia pada perlakuan fase pembungaan (F2). Tanaman kedelai menghasilkan produksi yang tinggi pada fraksi penipisan 0,4 untuk perlakuan fase pertumbuhan aktif dan fraksi penipisan 0,2 untuk perlakuan fase pembungaan dan fase pengisian polong
Computational study of the mechanism of Bcl-2 apoptotic switch
Programmed cell death - apoptosis is one of the most studied biological
phenomenon of recent years. Apoptotic regulatory network contains several
significant control points, including probably the most important one - Bcl--2
apoptotic switch. There are two proposed hypotheses regarding its internal
working - the indirect activation and direct activation models. Since these
hypotheses form extreme poles of full continuum of intermediate models, we have
constructed more general model with these two models as extreme cases.
By studying relationship between model parameters and steady-state response
ultrasensitivity we have found optimal interaction pattern which reproduces
behavior of Bcl-2 apoptotic switch. Our results show, that stimulus-response
ultrasensitivity is negatively related to spontaneous activation of Bcl-2
effectors - subgroup of Bcl-2 proteins. We found that ultrasensitivity requires
effector's activation, mediated by another subgroup of Bcl-2 proteins -
activators. We have shown that the auto-activation of effectors forms
ultrasensitivity enhancing feedback loop, only if mediated by monomers, but not
by oligomers. Robustness analysis revealed that interaction pattern proposed by
direct activation hypothesis is able to conserve stimulus-response dependence
and preserve ultrasensitivity despite large changes of its internal parameters.
This ability is strongly reduced as for the intermediate to indirect side of
the models.
Computer simulation of the more general model presented here suggest, that
stimulus-response ultrasensitivity is an emergent property of the direct
activation model, that cannot originate within model of indirect activation.
Introduction of indirect-model-specific interactions does not provide better
explanation of Bcl-2 functioning compared to direct model
Lung Cancer in Pulmonary Fibrosis: Tales of Epithelial Cell Plasticity
Lung epithelial cells exhibit a high degree of plasticity. Alterations to lung epithelial cell function are critically involved in several chronic lung diseases such as pulmonary fibrosis. Pulmonary fibrosis is characterized by repetitive injury and subsequent impaired repair of epithelial cells, which leads to aberrant growth factor activation and fibroblast accumulation. Increased proliferation and hyper- and metaplasia of epithelial cells upon injury have also been observed in pulmonary fibrosis; this epithelial cell activation might represent the basis for lung cancer development. Indeed, several studies have provided histopathological evidence of an increased incidence of lung cancer in pulmonary fibrosis. The mechanisms involved in the development of cancer in pulmonary fibrosis, however, remain poorly understood. This review highlights recently uncovered molecular mechanisms shared between lung cancer and fibrosis, which extend the current evidence of a common trait of cancer and fibrosis, as provided by histopathological observations. Copyright (C) 2011 S. Karger AG, Base
Randomized controlled trial of a coordinated care intervention to improve risk factor control after stroke or transient ischemic attack in the safety net: Secondary stroke prevention by Uniting Community and Chronic care model teams Early to End Disparities (SUCCEED).
BackgroundRecurrent strokes are preventable through awareness and control of risk factors such as hypertension, and through lifestyle changes such as healthier diets, greater physical activity, and smoking cessation. However, vascular risk factor control is frequently poor among stroke survivors, particularly among socio-economically disadvantaged blacks, Latinos and other people of color. The Chronic Care Model (CCM) is an effective framework for multi-component interventions aimed at improving care processes and outcomes for individuals with chronic disease. In addition, community health workers (CHWs) have played an integral role in reducing health disparities; however, their effectiveness in reducing vascular risk among stroke survivors remains unknown. Our objectives are to develop, test, and assess the economic value of a CCM-based intervention using an Advanced Practice Clinician (APC)-CHW team to improve risk factor control after stroke in an under-resourced, racially/ethnically diverse population.Methods/designIn this single-blind randomized controlled trial, 516 adults (≥40 years) with an ischemic stroke, transient ischemic attack or intracerebral hemorrhage within the prior 90 days are being enrolled at five sites within the Los Angeles County safety-net setting and randomized 1:1 to intervention vs usual care. Participants are excluded if they do not speak English, Spanish, Cantonese, Mandarin, or Korean or if they are unable to consent. The intervention includes a minimum of three clinic visits in the healthcare setting, three home visits, and Chronic Disease Self-Management Program group workshops in community venues. The primary outcome is blood pressure (BP) control (systolic BP <130 mmHg) at 1 year. Secondary outcomes include: (1) mean change in systolic BP; (2) control of other vascular risk factors including lipids and hemoglobin A1c, (3) inflammation (C reactive protein [CRP]), (4) medication adherence, (5) lifestyle factors (smoking, diet, and physical activity), (6) estimated relative reduction in risk for recurrent stroke or myocardial infarction (MI), and (7) cost-effectiveness of the intervention versus usual care.DiscussionIf this multi-component interdisciplinary intervention is shown to be effective in improving risk factor control after stroke, it may serve as a model that can be used internationally to reduce race/ethnic and socioeconomic disparities in stroke in resource-constrained settings.Trial registrationClinicalTrials.gov Identifier NCT01763203
Discrete Breathers
Nonlinear classical Hamiltonian lattices exhibit generic solutions in the
form of discrete breathers. These solutions are time-periodic and (typically
exponentially) localized in space. The lattices exhibit discrete translational
symmetry. Discrete breathers are not confined to certain lattice dimensions.
Necessary ingredients for their occurence are the existence of upper bounds on
the phonon spectrum (of small fluctuations around the groundstate) of the
system as well as the nonlinearity in the differential equations. We will
present existence proofs, formulate necessary existence conditions, and discuss
structural stability of discrete breathers. The following results will be also
discussed: the creation of breathers through tangent bifurcation of band edge
plane waves; dynamical stability; details of the spatial decay; numerical
methods of obtaining breathers; interaction of breathers with phonons and
electrons; movability; influence of the lattice dimension on discrete breather
properties; quantum lattices - quantum breathers. Finally we will formulate a
new conceptual aproach capable of predicting whether discrete breather exist
for a given system or not, without actually solving for the breather. We
discuss potential applications in lattice dynamics of solids (especially
molecular crystals), selective bond excitations in large molecules, dynamical
properties of coupled arrays of Josephson junctions, and localization of
electromagnetic waves in photonic crystals with nonlinear response.Comment: 62 pages, LaTeX, 14 ps figures. Physics Reports, to be published; see
also at http://www.mpipks-dresden.mpg.de/~flach/html/preprints.htm
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