Temperature dependence of density profiles for a cloud of non-interacting fermions moving inside a harmonic trap in one dimension

We extend to finite temperature a Green's function method that was previously proposed to evaluate ground-state properties of mesoscopic clouds of non-interacting fermions moving under harmonic confinement in one dimension. By calculations of the particle and kinetic energy density profiles we illustrate the role of thermal excitations in smoothing out the quantum shell structure of the cloud and in spreading the particle spill-out from quantum tunnel at the edges. We also discuss the approach of the exact density profiles to the predictions of a semiclassical model often used in the theory of confined atomic gases at finite temperature.Comment: 7 pages, 4 figure

Pannexin-1 channels bridge apoptosis to NLRP3 inflammasome activation.

Apoptosis can promote inflammation by triggering activation of the NLRP3 inflammasome (NLR family, pyrin domain containing 3). However, the molecular mechanisms regulating these processes are ill-defined. We recently reported that pannexin-1 is required to promote NLRP3 inflammasome assembly. We further demonstrate that differential cleavage of gasdermin D (GSDMD) by apoptotic caspases regulates inflammatory cell lysis. Here, we discuss our findings and perspectives for future studies

Moderating online child sexual abuse material (CSAM): Does self-regulation work, or is greater state regulation needed?

Social media platforms serve a role in the Internet age as crucial public forums connecting users around the world through a decentralised cyberspace. These platforms host high volumes of content and, as such, the role of content moderators (CMs) employed to safeguard users against harmful content like child sexual abuse material and gore is critical — however, despite how essential CMs are to the social media landscape, their work as “first responders” is complicated by legal and systemic debates over whether policing cyberspace should be left to the self-regulation of tech companies, or if greater state-regulation is required. In this scoping review, major debates in this area are identified and evaluated. This includes the issue of territorial jurisdiction, and how it obstructs traditional policing online; concerns over free speech and privacy if CMs are given greater powers; debates over whether tech companies should be legally liable for user-generated content and; the impacts (mental and professional) on the very CMs now operating as the new frontline against harmful, often traumatic, materials shared on social media. In outlining these issues, our objective is to highlight issues requiring further attention in order to best support CMs, and to enhance responses to harmful online content

Spin Excitations in a Fermi Gas of Atoms

We have experimentally investigated a spin excitation in a quantum degenerate Fermi gas of atoms. In the hydrodynamic regime the damping time of the collective excitation is used to probe the quantum behavior of the gas. At temperatures below the Fermi temperature we measure up to a factor of 2 reduction in the excitation damping time. In addition we observe a strong excitation energy dependence for this quantum statistical effect.Comment: 4 pages, 3 figure

Two-species magneto-optical trap with 40K and 87Rb

We trap and cool a gas composed of 40K and 87Rb, using a two-species magneto-optical trap (MOT). This trap represents the first step towards cooling the Bose-Fermi mixture to quantum degeneracy. Laser light for the MOT is derived from laser diodes and amplified with a single high power semiconductor amplifier chip. The four-color laser system is described, and the single-species and two-species MOTs are characterized. Atom numbers of 1x10^7 40K and 2x10^9 87Rb are trapped in the two-species MOT. Observation of trap loss due to collisions between species is presented and future prospects for the experiment are discussed.Comment: 4 pages, 4 figures; accepted for publication in Physical Review

Content moderators’ strategies for coping with the stress of moderating content online

Content moderators are exposed to a range of stressors at work, including analysing content that has been flagged as harmful. However, not much is known about their specific coping strategies. Depth interviews were conducted with 11 content moderators exposed to child sexual abuse material (CSAM) as part of their job, and thematically analysed to investigate both individual coping strategies and those deployed organisationally. Results highlighted the importance of social support especially from colleagues. Supportive relationships fulfilled several needs including helping content moderators process emotions, normalise their reactions and reducing feelings of isolation. Additionally, the ability to create boundaries between work and home life was important for distancing and distracting themselves from the work. Moderators expressed a preference for mandatory, individual therapy with professionals who had specific experience supporting those exposed to CSAM and reported disclosure was hindered if not, due to worries about traumatising the therapist. How content moderators cope and can be further supported are discussed

Superfluidity in the interior-gap states

We investigate superfluidity in the interior-gap states proposed by Liu and Wilczek. At weak coupling, we find the {\em gapless} interior-gap state unstable in physically accessible regimes of the parameter space, where the superfluid density is shown to be always negative. We therefore conclude that the spatially-uniform interior-gap phase is extremely unstable unless it is fully gapped; in this case, however, the state is rather similar to conventional BCS states.Comment: To appear in Physical Review