Expanded iron uta spectra - Probing the thermal stability limits in AGN clouds

The Fe unresolved transition arrays (UTAs) produce prominent features in the 15-17 Å wavelength range in the spectra of active galactic nuclei (AGNs). Here, we present new calculations of the energies and oscillator strengths of inner-shell lines from Fe XIV, Fe XV, and Fe XVI. These are crucial ions since they are dominant at inflection points in the gas thermal stability curve, and UTA excitation followed by autoionization is an important ionization mechanism for these species. We incorporate these, and data reported in previous papers, into the plasma simulation code Cloudy. This updated physics is subsequently employed to reconsider the thermally stable phases in absorbing media in AGNs. We show how the absorption profile of the Fe XIV UTA depends on density, due to the changing populations of levels within the ground configuration. © 2013. The American Astronomical Society. All rights reserved.

On the Limits of Exceptionalism: Principles and Practice in the Pursuit of Alternatives to Full EU Membership

Few states have been less uncomfortable with the relationship they have with the EU than the United Kingdom as a member and Turkey as an associate and would-be member. Both states currently find themselves questioning the substance and future of these relationships with domestic actors and, notably in the Turkish case, external EU voices actively advocating alternatives. While much discussion, particularly in the UK case, has focused on the advantages and disadvantages of particular existing arrangements (e.g. European Economic Area, Swiss bilateralism), this paper considers the broader principles and practices that the EU has to date either explicitly developed or implicitly established to govern the nature and substance of alternatives to [full] EU membership. It assesses the principled, practical and political limitations that exist in establishing alternatives to full membership for states seeking – or having sought for them – the accommodation of their exceptionalism. In doing so the paper considers the potential limits to a renegotiated EU membership for the UK and to an alternative short of full membership for Turkey. It also reflects on the precedent-setting consequences of any new arrangements that the EU might reach with either state for what forms membership and a relationship short of membership might take in the future.

Performance Limits of MIMO Systems with Nonlinear Power Amplifiers

The development of 5G enabling technologies brings new challenges to the design of power amplifiers (PAs). In particular, there is a strong demand for low-cost, nonlinear PAs which, however, introduce nonlinear distortions. On the other hand, contemporary expensive PAs show great power efficiency in their nonlinear region. Inspired by this trade-off between nonlinearity distortions and efficiency, finding an optimal operating point is highly desirable. Hence, it is first necessary to fully understand how and how much the performance of multiple-input multiple-output (MIMO) systems deteriorates with PA nonlinearities. In this paper, we first reduce the ergodic achievable rate (EAR) optimization from a power allocation to a power control problem with only one optimization variable, i.e. total input power. Then, we develop a closed-form expression for the EAR, where this variable is fixed. Since this expression is intractable for further analysis, two simple lower bounds and one upper bound are proposed. These bounds enable us to find the best input power and approach the channel capacity. Finally, our simulation results evaluate the EAR of MIMO channels in the presence of nonlinearities. An important observation is that the MIMO performance can be significantly degraded if we utilize the whole power budget.

European Union Cross-Border Cooperation as Conflict Transformation:Potential and Limits

Cross-border cooperation as conflict transformation provides a potential strategy for the European Union (EU) to help realise its founding peacebuilding objective. A wealth of cross-border cooperation activity sponsored by the EU spans a quarter of a century. Although the conflict transformation capacity of that cooperation is questionable in some border regions there is evidence to suggest that it has delivered peacebuilding dividends in other border regions. However, EU cross-border cooperation as conflict transformation faces a number of significant twenty-first century challenges including: ghost borders of the communal imagination; EU external border securitization; perceptions of EU and Russian empire-building; and the Mediterranean transmigrant/refugee crisis. It is argued that these challenges pose significant obstacles to EU cross-border cooperation as conflict transformation and undermine the peacebuilding objective of European integration.

Economic Stability and Economic Governance in the Euro Area:What the European Crisis Can Teach on the Limits of Economic Integration

The recent European economic crisis has dramatically exposed the failures of
the various institutional mechanisms in place to maintain economic stability
in Europe, and has unveiled the difficulty in achieving international coordination
on fiscal and financial stability policies. Drawing on the European
experience, this article analyzes the concept of economic stability in international
law and highlights the peculiar problems connected to its maintenance
or promotion. First, we demonstrate that policies that safeguard and
protect economic stability are largely regulated and managed at the national
level, due to their inextricable relationship with the exercise of national political
power. Until recently, more limited levels of pan-European integration
did not make the coordination of economic stability policies seem necessary.
However, a much deeper level of economic integration makes it very difficult
to tackle an international economic crisis through national responses. If EU
Member states wish to maintain and deepen economic integration, they
must accept an erosion of sovereignty over their economic stability policies.
This will not only deprive states of a fundamental anchor of political power,
but also create a challenge for the maintenance of democratic control over
economic policies. Second, this article argues that soft law approaches are
likely ineffective in enforcing the regulatory disciplines required to ensure
economic stability.

Jubilee and the Limits of African American Freedom after Emancipation

Scholarship generated in the post-civil rights US underpins a growing consensus that any honest confrontation with the American past requires an acknowledgment both of the nation’s foundations in racially-based slave labour and of the critical role that the enslaved played in ending that system. But scholars equally need to examine why the end of slavery did not deliver freedom, but instead – after a short-lived ‘jubilee’ during which freedpeople savoured their ‘brief moment in the sun’ – opened up a period of extreme repression and violence. This article traces the political trajectory of one prominent ex-slave and Republican party organiser, Elias Hill, to assess the constraints in which black grassroots activists operated. Though mainly concerned with the dashed hopes of African Americans, their experience of a steep reversal is in many ways the shared and profoundly significant legacy of ex-slaves across the former plantation societies of the Atlantic world.

Endothelial cell-derived Pentraxin 3 limits the vasoreparative therapeutic potential of Circulating Angiogenic Cells

AIMS: Circulating Angiogenic Cells (CACs) promote revascularization of ischemic tissues although their underlying mechanism of action and the consequences of delivering varying numbers of these cells for therapy remain unknown. This study investigates molecular mechanisms underpinning CAC modulation of blood vessel formation.

METHODS & RESULTS: CACs at low (2x10(5)cells/ml) and mid (2x10(6)cells/ml) cellular densities significantly enhanced endothelial cell (EC) tube formation in vitro, while high density CACs (2x10(7)cells/ml) significantly inhibited this angiogenic process. In vivo, Matrigel-based angiogenesis assays confirmed mid-density CACs as pro-angiogenic and high density CACs as anti-angiogenic. Secretome characterization of CAC-EC conditioned media identified pentraxin 3 (PTX3) as only present in the high density CAC-EC co-culture. Recombinant PTX3 inhibited endothelial tube formation in vitro and in vivo Importantly, our data revealed that the anti-angiogenic effect observed in high density CAC-EC co-cultures was significantly abrogated when PTX3 bioactivity was blocked using neutralizing antibodies or PTX3 siRNA in endothelial cells. We show evidence for an endothelial source of PTX3, triggered by exposure to high density CACs. In addition, we confirmed that PTX3 inhibits FGF2-mediated angiogenesis, and that the PTX3 N-terminus, containing the FGF-binding site, is responsible for such anti-angiogenic effects.

CONCLUSIONS: Endothelium, when exposed to high density CACs, releases PTX3 which markedly impairs the vascular regenerative response in an autocrine manner. Therefore, CAC density and accompanying release of angiocrine PTX3 are critical considerations when using these cells as a cell therapy for ischemic disease.