Radiation Damage Studies of Silicon Photomultipliers

We report on the measurement of the radiation hardness of silicon photomultipliers (SiPMs) manufactured by Fondazione Bruno Kessler in Italy (1 mm$^2$ and 6.2 mm$^2$), Center of Perspective Technology and Apparatus in Russia (1 mm$^2$ and 4.4 mm$^2$), and Hamamatsu Corporation in Japan (1 mm$^2$). The SiPMs were irradiated using a beam of 212 MeV protons at Massachusetts General Hospital, receiving fluences of up to $3 \times 10^{10}$ protons per cm$^2$ with the SiPMs at operating voltage. Leakage currents were read continuously during the irradiation. The delivery of the protons was paused periodically to record scope traces in response to calibrated light pulses to monitor the gains, photon detection efficiencies, and dark counts of the SiPMs. The leakage current and dark noise are found to increase with fluence. Te leakage current is found to be proportional to the mean square deviation of the noise distribution, indicating the dark counts are due to increased random individual pixel activation, while SiPMs remain fully functional as photon detectors. The SiPMs are found to anneal at room temperature with a reduction in the leakage current by a factor of 2 in about 100 days.Comment: 35 pages, 25 figure

Direct observation of charge inversion by multivalent ions as a universal electrostatic phenomenon

We have directly observed reversal of the polarity of charged surfaces in water upon the addition of tri- and quadrivalent ions using atomic force microscopy. The bulk concentration of multivalent ions at which charge inversion reversibly occurs depends only very weakly on the chemical composition, surface structure, size and lipophilicity of the ions, but is dominated by their valence. These results support the theoretical proposal that spatial correlations between ions are the driving mechanism behind charge inversion.Comment: submitted to PRL, 26-04-2004 Changed the presentation of the theory at the end of the paper. Changed small error in estimate of prefactor ("w" in first version) of equation

‘If They Don’t Listen to Us, they Deserve It’: The Effect of External Efficacy and Anger on the Perceived Legitimacy of Hacking

We conducted two studies examining the factors underlying individuals’ legitimization of hackers (digital actors operating on the internet). Drawing on the social banditry framework, and research on political action, we focused on the mediating role of anger in the association between external political efficacy and perceived legitimization of hackers’ actions. Specifically, we manipulated whether the system was responsive to participants’ demands following unfair treatment in a university (Study 1) and in an online work platform (Study 2) context. In Study 1 (N = 259) British undergraduate students read about unfair ‘grading’ practices. They were then informed that the management was either willing (high external political efficacy) or unwilling (low external political efficacy) to investigate the matter. In Study 2 (N = 222), British participants were recruited via Prolific Academic and were presented with a scenario describing an unfair rejection of their work. They were then informed that the platform admin was either willing or not willing to investigate their case. Across studies, participants were informed that hackers had attacked the website. Supporting the social banditry framework, results indicated that individuals who perceive the system as unresponsive to their demands tended to legitimize hackers’ actions via stronger perceived anger against the system. Implications of the results, and future directions are discussed

The dangers of distrustful complacency: Low concern and low political trust combine to undermine compliance with governmental restrictions in the emerging Covid-19 pandemic

People comply with governmental restrictions for different motives, notably because they are concerned about the issue at hand or because they trust their government to enact appropriate regulations. The present study focuses on the role of concern and political trust in people’s willingness to comply with governmental restrictions during the Covid-19 pandemic. We conducted a survey amongst Italian and French participants (N = 372) in March 2020 while both countries had imposed full lockdown. Moreover, a subsample of participants reported on their actual levels of compliance one week later (N = 130). We hypothesised that either concern or trust should be sufficient to sustain participants’ willingness to comply and actual behaviour, but that the absence of both (distrustful complacency) would reduce compliance significantly. Results supported this hypothesis. We discuss implications of the interaction between concern and trust for public behaviour strategies as the pandemic progresses

Power Moderates the Effects of Social Dominance Orientation on Punishment: An Experimental Analysis

In this study, it was hypothesized that experimentally manipulated levels of power would moderate the association of dispositional social dominance orientation (SDO) with preferences for harsh punishment. In particular, we expected to detect a stronger effect for dispositional SDO in the low-power condition, relying on the notion that low power enhances sensitivity to threats to the status quo, and that high SDO individuals are particularly motivated to enforce hierarchy-enhancing measures as punishment. SDO scores were measured two months prior to the experiment, and then immediately after the experimental session. As expected, preexperimental SDO interacted with the power manipulation. We found stronger preexperimental SDO effects on punishment among low-power participants. We also anticipated and found that individuals high in SDO increased further their postexperimental SDO scores if assigned to a high-power condition. The discussion focuses on the importance of SDO effects among low-status groups and on how situational roles shape dispositional self-descriptions

Nurr1 Modulation Mediates Neuroprotective Effects of Statins

The ligand-sensing transcription factor Nurr1 emerges as a promising therapeutic target for neurodegenerative pathologies but Nurr1 ligands for functional studies and therapeutic validation are lacking. Here pronounced Nurr1 modulation by statins for which clinically relevant neuroprotective effects are demonstrated, is reported. Several statins directly affect Nurr1 activity in cellular and cell-free settings with low micromolar to sub-micromolar potencies. Simvastatin as example exhibits anti-inflammatory effects in astrocytes, which are abrogated by Nurr1 knockdown. Differential gene expression analysis in native and Nurr1-silenced cells reveals strong proinflammatory effects of Nurr1 knockdown while simvastatin treatment induces several neuroprotective mechanisms via Nurr1 involving changes in inflammatory, metabolic and cell cycle gene expression. Further in vitro evaluation confirms reduced inflammatory response, improved glucose metabolism, and cell cycle inhibition of simvastatin-treated neuronal cells. These findings suggest Nurr1 involvement in the well-documented but mechanistically elusive neuroprotection by statins

Lithographically fabricated nanopore-based electrodes for electrochemistry

We report a new technique for fabricating electrodes for electrochemical applications with lateral dimensions in the range 15−200 nm and a reproducible, well-defined geometry. This technique allows determining the electrode size by electron microscopy prior to electrochemical measurements and without contamination of the metal electrode. We measured the diffusion-limited current with stepped-current voltammetry and showed that its dependence on electrode size can be quantitatively understood if the known geometry of the electrodes is explicitly taken into account

Multi-Purpose Cyber Environment for Maritime Sector

The cyber attack surface in a maritime environment is constantly growing. More current information and computer technologies are being used on cargo and passenger ships to save on operational costs and increase navigational safety. Along with the growing reliance on automation, the risk of a disruption to a vessel's critical systems by drawing on the wrong inputs from sensors to change the behaviour of the actuators has significantly increased. Traditional operational technological systems are much more complicated to update than the automatic software updates we see in information technology systems. To better understand existing cyber threats in the maritime sector and increase cybersecurity resilience, this paper aims to replicate the digital components of a ship's bridge to examine scenarios when the bridge system loses connectivity, receives the wrong inputs from sensors, or the internal system becomes compromised. The simulator differentiates fundamentally from traditional simulators or digital twins in the maritime sector that focus on training seafarers. This environment generates data streams that are similar to those on board a ship. Those data streams can be analysed, modified and spoofed to observe the effects. The effects can be technical but it is equally necessary to analyse how human beings would react in specific circumstances. Our work provides the opportunity to isolate the ship network traffic, conduct penetration testing, find cybersecurity vulnerabilities on devices, and execute cyber attacks without the dangers associated with running such scenarios on a vessel in the open sea.</jats:p