Social media: myths from the first 2000 years

The Economist’s Tom Standage is first up in Polis’ Media Agenda Talks lecture series – his book Writing On the Wall, a history of social media is reviewed here by Polis reporter Kyle Bowe

Internet freedom in Iran: attitudes to anonymity, privacy and FOI

In the lead up to this year’s high level event to review the progress of the goals outlined at the World Summit on the Information Society (WSIS), stakeholders gathered in Geneva for the WSIS forum on March 25. Kyle Bowen, researcher at Small Media, looks at some of the findings of his organisation’s latest report, which is based on an analysis of Iran’s country profile presentation at the forum, which enabled the country to discuss its objectives, achievements and concerns regarding internet governance

Chaos and Control: The Competing Tensions of Internet Governance in Iran

Kyle Bowen, an LSE Media and Communications alumnus who is now a researcher at Small Media, an NGO that seeks the free flow of information, particularly in Iran, discusses the implications of a new report on Iran’s approach to internet governance

Reputation and accountability: where are the checks and balances with social media?

How have changes in the media landscape have affected the practice of reputation management? Public Relations Executive Tim Burt says that the proliferation of social media has greatly limited the amount of editorial control that can be exercised over the dissemination of information. Burt argues that social media have eroded the system of “checks and balances” that historically governed the reporting process, a development that has (unsurprisingly) led to high levels of anxiety among CEOs. It has made it more difficult for Burt to manage the reputations of his corporate clientele, but he is also cautiously optimistic regarding how a diffuse media environment might increase democratic accountability. Polis Intern Kyle Bowen takes up some of the issues that emerged from the latest Polis Media Agenda Talk

A Case for Chiral Contributions to Nondipole Effects in Photoionization Using Linearly Polarized Soft X-rays

Modelling angular distributions of photoelectrons requires making accurate approximations of both the incoming light and the behavior of bound electrons. The experimental determination of photoelectron angular distributions is crucial to the development of accurate theoretical models governing the light-matter interaction. To date, many models have relied upon the dipole approximation, which assumes a constant electric field as the source of ionization. Despite knowing that the dipole approximation would break down as photon energy increased, the precise limit was unclear. Over the past two decades, a strong case has been made that corrections to the dipole approximation are necessary for accurately describing photoionization using soft x-rays (100 – 1000 eV). This energy region is widely studied, as it has become more readily accessible thanks to third-generation synchrotron radiation facilities. This work provides experimental evidence for first-order corrections to the dipole approximation, known as nondipole effects, for atoms and molecules, focusing on Xe 3d photoionization, which showcases the role of interchannel coupling in nondipole angular distributions, N 1s photoionization from molecular nitrogen in an attempt to settle a dispute over molecular nondipole effects, and C 1s photoionization from the chiral molecule camphor, which provides the first-ever experimental determination of a theoretically predicted chiral-specific nondipole effect. All of the experiments were performed using electron time-of-flight spectroscopy at the Advanced Light Source (ALS) at Lawrence Berkeley National Laboratory (LBNL)

The effect of aperture size on gigaseal formation

Patch clamping, the gold standard for ion channel studies, is entirely dependent on formation of a high resistance seal between cell membrane and patching site,known as gigaseal. As this process is laborious and time consuming, there have been many attempts to develop automated high throughput chip-based patch clamping devices. In spite of recent advances, these devices still cannot form gigaseals relying instead on less tight seals that impede their ability to measure the pA ionic currents passing through single ion channels. Progress is presently limited due to a lack of understanding of the physical and chemical mechanisms underlying gigaseal formation. In all forms of patch clamping access to the cell is achieved via a small aperture. Here, we systematically examine the influence of aperture size, micropipette rim morphology, and surface roughness on gigaseal formation in conventional patch clamping using micro/nanofabrication and modelling techniques. Our results show that smaller aperture sizes lead to improved seal formation within a range of x-y. For aperture sizes out of this range, either bigger or smaller, gigaseal formation is very difficult if not impossible. While in the literature the surface quality of patching sites is only described by average surface roughness, this research reveals that parameters such as: developed interfacial area ratio, valley void volume of the surface, ratio of core void volume to core material volume, and maximum peak to valley distance play more important roles in seal formation. Furthermore,these parameters are size dependent; as a result glass micropipettes with smaller aperture sizes are flatter and have lower water retentionability resulting in better seals. Results of this work support the practical knowledge that pipettes having smaller apertures form better seals

Ultrasound regulated flexible protein materials: Fabrication, structure and physical-biological properties.

Ultrasound can be used in the biomaterial field due to its high efficiency, easy operation, no chemical treatment, repeatability and high level of control. In this work, we demonstrated that ultrasound is able to quickly regulate protein structure at the solution assembly stage to obtain the designed properties of protein-based materials. Silk fibroin proteins dissolved in a formic acid-CaCl solution system were treated in an ultrasound with varying times and powers. By altering these variables, the silks physical properties and structures can be fine-tuned and the results were investigated with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), gas permeability and water contact angle measurements. Ultrasonic treatment aids the interactions between the calcium ions and silk molecular chains which leads to increased amounts of intermolecular β-sheets and α-helix. This unique structural change caused the silk film to be highly insoluble in water while also inducing a hydrophilic swelling property. The ultrasound-regulated silk materials also showed higher thermal stability, better biocompatibility and breathability, and favorable mechanical strength and flexibility. It was also possible to tune the enzymatic degradation rate and biological response (cell growth and proliferation) of protein materials by changing ultrasound parameters. This study provides a unique physical and non-contact material processing method for the wide applications of protein-based biomaterials

Extensive Natural Intraspecific Variation in Stoichiometric (C:N:P) Composition in Two Terrestrial Insect Species

Heterotrophic organisms must obtain essential elements in sufficient quantities from their food. Because plants naturally exhibit extensive variation in their elemental content, it is important to quantify the within-species stoichiometric variation of consumers. If extensive stoichiometric variation exists, it may help explain consumer variation in life-history strategy and fitness. To date, however, research on stoichiometric variation has focused on interspecific differences and assumed minimal intraspecific differences. Here this assumption is tested. Natural variation is quantified in body stoichiometry of two terrestrial insects: the generalist field cricket, Gryllus texensis Cade and Otte (Orthoptera: Gryllidae) and a specialist curculionid weevil, Sabinia setosa (Le Conte) (Coleoptera: Curculionidae). Both species exhibited extensive intraspecific stoichiometric variation. Cricket body nitrogen content ranged from 8–12% and there was a four-fold difference in body phosphorus content, ranging from 0.32–1.27%. Body size explained half this stoichiometric variation, with larger individuals containing less nitrogen and phosphorus. Weevils exhibited an almost three-fold difference in body phosphorus content, ranging from 0.38–0.97%. Overall, the variation observed within each of these species is comparable to the variation previously observed across almost all terrestrial insect species

Targeting EZH2 and PRC2 dependence as novel anticancer therapy

Distinctive patterns of chromatin modification control gene expression and define cellular identity during development and cell differentiation. Polycomb repressive complex 2 (PRC2), the sole mammalian enzymatic complex capable of establishing gene-repressive high-degree methylation of histone H3 at lysine 27 (H3K27), plays crucial roles in regulation of normal and malignant hematopoiesis. Recently, increasing evidence has indicated that recurrent gain-of-function mutation and overexpression of EZH2, the catalytic subunit of PRC2, drive and promote malignant transformation such as B-cell lymphomagenesis, providing a rationale for PRC2 inhibition as a novel anticancer strategy. Here, we summarize the recently developed strategies for inhibition of PRC2, which include a series of highly specific, highly potent, small-molecule inhibitors of EZH2 and EZH1, an EZH2-related methyltransferase. PRC2 establishes functional crosstalk with numerous epigenetic machineries during dynamic regulation of gene transcription. Perturbation of such functional crosstalk caused by genetic events observed in various hematologic cancers, such as inactivation of SNF5 and somatic mutation of UTX, confers PRC2 dependence, thus rendering an increased sensitivity to PRC2 inhibition. We discuss our current understanding of EZH2 somatic mutations frequently found in B-cell lymphomas and recurrent mutations in various other epigenetic regulators as novel molecular predictors and determinants of PRC2 sensitivity. As recent advances have indicated a critical developmental or tumor-suppressive role for PRC2 and EZH2 in various tissue types, we discuss concerns over potentially toxic or even adverse effects associated with EZH2/1 inhibition in certain biological contexts or on cancer genetic background. Collectively, inhibition of PRC2 catalytic activity has emerged as a promising therapeutic intervention for the precise treatment of a range of genetically defined hematologic malignancies and can be potentially applied to a broader spectrum of human cancers that bear similar genetic and epigenetic characteristics. Published by Elsevier Inc. on behalf of ISEH - International Society for Experimental Hematology