On the radial distribution of Galactic cosmic rays

The spectrum and morphology of the diffuse Galactic gamma-ray emission carries valuable information on cosmic ray (CR) propagation. Recent results obtained by analyzing Fermi-LAT data accumulated over seven years of observation show a substantial variation of the CR spectrum as a function of the distance from the Galactic Center. The spatial distribution of the CR density in the outer Galaxy appears to be weakly dependent upon the galactocentric distance, as found in previous studies as well, while the density in the central region of the Galaxy was found to exceed the value measured in the outer Galaxy. At the same time, Fermi-LAT data suggest a gradual spectral softening while moving outward from the center of the Galaxy to its outskirts. These findings represent a challenge for standard calculations of CR propagation based on assuming a uniform diffusion coefficient within the Galactic volume. Here we present a model of non-linear CR propagation in which transport is due to particle scattering and advection off self-generated turbulence. We find that for a realistic distribution of CR sources following the spatial distribution of supernova remnants and the space dependence of the magnetic field on galactocentric distance, both the spatial profile of CR density and the spectral softening can easily be accounted for.Comment: 6 pages, 3 figures. Accepted for publivation to MNRAS letter

Cosmic ray driven Galactic winds

The escape of cosmic rays from the Galaxy leads to a gradient in the cosmic ray pressure that acts as a force on the background plasma, in the direction opposite to the gravitational pull. If this force is large enough to win against gravity, a wind can be launched that removes gas from the Galaxy, thereby regulating several physical processes, including star formation. The dynamics of these cosmic ray driven winds is intrinsically non-linear in that the spectrum of cosmic rays determines the characteristics of the wind (velocity, pressure, magnetic field) and in turn the wind dynamics affects the cosmic ray spectrum. Moreover, the gradient of the cosmic ray distribution function causes excitation of Alfven waves, that in turn determine the scattering properties of cosmic rays, namely their diffusive transport. These effects all feed into each other so that what we see at the Earth is the result of these non-linear effects. Here we investigate the launch and evolution of such winds, and we determine the implications for the spectrum of cosmic rays by solving together the hydrodynamical equations for the wind and the transport equation for cosmic rays under the action of self-generated diffusion and advection with the wind and the self-excited Alfven waves.Comment: 14 pages, 15 figures. Accepted for publication to MNRAS main journa

Soldiers, Civilians, and Multilateral Humanitarian Intervention

Approval from the United Nations or NATO appears to have become a necessary condition for US humanitarian military intervention. Conventional explanations emphasizing the pull of legitimacy norms cannot fully account for this given that US policymakers vary considerably in their attachment to multilateralism. This article argues that America’s military leaders, who are consistently skeptical about humanitarian intervention and tend to emphasize its costs, play a central role in making multilateral approval necessary. As long as the top-ranking generals express strong reservations about intervention and no clear threat to US national security exists, they can veto the use of force. In such circumstances, even heavyweight “humanitarian hawks” among the civilian leadership, who initially may have wanted to bypass multilateral bodies to maximize US freedom of action, can be expected to recognize the need for UN or NATO approval—if only as a means of mollifying the generals by reassuring them about the prospect of sustained multilateral burden sharing. Two case studies drawing on interviews with senior civilian and military officials illustrate and probe the plausibility of the argument.Research on this article was supported by a fellowship in foreign policy that the author held at the Brookings Institution in Washington, D.C.http://dx.doi.org/10.1080/09636412.2015.1036626This is the final version of the article. It first appeared from Taylor & Franics via http://dx.doi.org/10.1080/09636412.2015.103662

Authorising humanitarian intervention: A five-point defence of existing multilateral procedures

AbstractEven scholars who support multilateralism in principle frequently question the value of securing approval from existing multilateral bodies for humanitarian intervention. The United Nations (UN) and regional organisations such as NATO, the argument goes, are far from democratic; furthermore, multilateralism is often a recipe for doing nothing; therefore, unauthorised intervention should be permissible in circumstances of ‘humanitarian necessity’. This article maintains that although today’s multilateral organisations and related procedures for authorising armed intervention may be suboptimal, they have significant output legitimacy. First, existing authorisation procedures reduce the risk of destabilising conflict spirals among powerful states. Second, they diminish the likelihood that humanitarianism will be used as a pretext. Third, they reduce epistemic problems concerning the identification of a just cause for intervention and thus the risk of accidental abuse. Fourth, they minimise the ‘moral hazard’ of humanitarian intervention. Finally, compliance with multilateral procedures is increasingly required for successful peacebuilding. This leads me to conclude that humanitarian warfare should always be authorised by the UN or regional multilateral organisations.This is the final version of the article. It first appeared from Cambridge University Press via http://dx.doi.org/10.1017/S026021051600027

Should humanitarian interveners promote democracy after genocide?

Scholars and policymakers in the West commonly hold that liberal countries that intervene to stop genocide subsequently ought to establish democratic political institutions to enable peaceful collective self-determination. I argue that this guidance is problematic. First, introducing electoral democracy in deeply ethnically divided societies – especially but not only after genocide – often results in either tyrannical majority rule or deadlocked decision making rather than inclusive self-determination. Second, normatively speaking, John Rawls made a strong case that inclusive self-determination can be achieved through ‘decent,’ less than democratic political structures that enable group-based representation. Bringing these insights together, I argue that particularly for postgenocidal societies that lack prior experience with liberal democratic rule, outside interveners should stop short of actively promoting full electoral democracy and instead consider promoting hybrid political institutions that combine popularly elected bodies with customary authority structures. Such hybrid institutions can prevent tyrannical majority rule as well as decision-making deadlock. They are also likely to fit better with local culture. Therefore, they may offer a more robust foundation for peaceful self-determination. A discussion of hybrid institutions in postwar Somaliland and Bougainville illustrates how these arrangements can facilitate peaceful self-determination in practice.</jats:p

The Paradox of Safe Areas in Ethnic Civil Wars

Safe areas established by powerful states can improve short-term civilian protection during ethnic civil wars. Paradoxically, however, they may worsen the plight of vulnerable civilians over the medium term. This can occur in three ways. First, when safe areas encompass sizeable territories within a broader conflict zone, they may reduce incentives for protected groups to compromise during peace negotiations, thus prolonging hostilities. Second, there is a nontrivial possibility that protected groups will use the safe areas as a base for launching high-risk offensives, deliberately putting civilians at risk in the hope of drawing the protection forces more deeply into the war. Third, safe areas may embolden protected groups to seek unilateral secession, further increasing the risk of conflict escalation. By elucidating the causal mechanisms involved, this article helps us assess the probability of these outcomes occurring. States that consider intervening militarily to establish safe areas in ethnic civil wars need to weigh the short-term benefits against these possible longer-term downsides.</jats:p

A high-throughput, straightforward procedure for biomonitoring organomercury species in human hair

Mercury is a pervasive and concerning pollutant due to its toxicity, mobility, and tendency to biomagnify in aquatic and terrestrial ecosystems. Speciation analysis is crucial to assess exposure and risks associated with mercury, as different mercury species exhibit varying properties and toxicities. This study aimed at developing a selective detection method for organic mercury species in a non-invasive biomonitoring matrix like human hair. The method is based on frontal chromatography (FC) in combination with inductively coupled plasma mass spectrometry (ICP-MS), using a low pressure, homemade, anion exchange column inserted in a standard ICP-MS introduction system, without requiring high-performance liquid chromatography (HPLC) hyphenation. In addition to the extreme simplification and cost reduction of the chromatographic equipment, the proposed protocol involves a fast, streamlined and fully integrated sample preparation process (in contrast to existing methods): the optimized procedure features a 15-min ultrasonic assisted extraction procedure and 5&nbsp;min analysis time. Consequently, up to 100 samples could be analyzed daily, making the method highly productive and suitable for large-scale screening programs in public and environmental health. Moreover, the optimized procedure enables a limit of detection (LOD) of 5.5&nbsp;μg/kg for a 10&nbsp;mg hair microsample. All these features undeniably demonstrate a significant advancement in routine biomonitoring practices. To provide additional evidence, the method was applied to forty-nine human hair samples from individuals with varying dietary habits successfully finding a clear correlation between methylmercury levels (ranging from 0.02 to 3.2&nbsp;mg/kg) in hair and fish consumption, in line with previous literature data

Ultrafast Electrochemical Self-Doping of Anodic Titanium Dioxide Nanotubes for Enhanced Electroanalytical and Photocatalytic Performance

This study explores an ultrarapid electrochemical self-doping procedure applied to anodic titanium dioxide (TiO2) nanotube arrays in an alkaline solution to boost their performance for electroanalytical and photocatalytic applications. The electrochemical self-doping process (i.e., the creation of surface Ti3+ states by applying a negative potential) is recently emerging as a simpler and cleaner way to improve the electronic properties of TiO2 compared to traditional chemical and high-temperature doping strategies. Here, self-doping was carried out through varying voltages and treatment times to identify the most performing materials without compromising their structural stability. Interestingly, cyclic voltammetry characterization revealed that undoped TiO2 shows negligible activity, whereas all self-doped materials demonstrate their suitability as electrode materials: an outstandingly short 10 s self-doping treatment leads to the highest electrochemical activity. The electrochemical detection of hydrogen peroxide was assessed as well, demonstrating a good sensitivity and a linear detection range of 3–200 µM. Additionally, the self-doped TiO2 nanotubes exhibited an enhanced photocatalytic activity compared to the untreated substrate: the degradation potential of methylene blue under UV light exposure increased by 25% in comparison to undoped materials. Overall, this study highlights the potential of ultrafast electrochemical self-doping to unleash and improve TiO2 nanotubes performances for electroanalytical and photocatalytic applications

Unveiling the complexity of japanese metallic threads

In the framework of an extensive survey campaign on a collection of Japanese samurai armors, metallic threads from different parts of the traditional equipment were studied by several analytical techniques. The collection of armors belongs to Museo delle Culture (Lugano, Switzerland) and it is composed of ten elements, which date back from the 15th to 20th century. Metallic threads under study come from six of ten elements of the collection and represent a complex and unique multimaterial, which shows specific characteristics in Japanese tradition (kinran). The multianalytical approach based on ATR-FTIR spectroscopy and SEM-EDX analysis, together with a careful observation with optical and digital microscopy, permitted to obtain a complete characterization of materials, which have shown a great variability in metal foils and in organic adhesives (urushi, animal glue, starch). Gold and silver turned out to be not so largely used as scholars thought, while aluminum showed a great diffusion. Within the collection of analyzed armors, the obtained results allowed us for the first time to get a complete comprehension of materials and techniques used by Japanese craftsmen, and to observe differences in the quality of the materials and in manufacture technology over the centuries