Primordial Black Holes (PBHs) might have formed in the early Universe as a consequence of the collapse of density fluctuations with an amplitude above a critical value δ c : the formation threshold. Although for a radiation-dominated Universe δ c remains constant, if the Universe experiences some dust-like phases (e.g. phase transitions) δ c might decrease, improving the chances of PBH formation. We studied the evolution of δ c during the QCD phase transition epoch within three different models: Bag Model (BM), Lattice Fit Model (LFM), and Crossover Model (CM). We found that the reduction on the background value of δ c can be as high as 77% (BM), which might imply a ∼ 10 −10 probability of PBHs forming at the QCD epoch.

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The aviation industry plays a vital role in supporting economies and connecting people worldwide; it is a cornerstone of modern life. However, user experience of air travel is often marked by frustration, stress and confusion. Indeed, over the last decade, traveler satisfaction with air travel experiences has steadily declined. This paper describes fieldwork in the form of 63 interviews (using a range of user research methods) that aims to understand the needs of air travelers. Key insights from this process are presented and a conceptual system design, based on connecting travelers using existing social media systems, is introduced. Ultimately, this paper argues that applying innovation in social media technology to air travel has the potential to improve user experiences and reduce industry costs, making travelling smoother, cheaper and more satisfying.

The aviation industry is fundamental to today's connected global economies, rapidly and effectively linking people, places and cultures. However, aviation struggles to provide a high quality of service; air travelers typically report dissatisfaction and frustration with their experiences. This paper describes fieldwork in the form of 63 interviews that aims to understand the needs of air travelers in order to improve user experiences during and around air travel. Three themes from this traveler-centered user research process are presented and the design of FlyTalk, a mobile phone application inspired by this data and tailored to the needs of air travelers is described. FlyTalk collates existing information about airports and their procedures, presents this to users in a location and context aware interface and seamlessly integrates social media features connecting travelers with both their service providers and each other. This paper argues air travel is an important but overlooked domain for HCI practitioners and that mobile applications that meet user needs in this scenario have the potential to reduce travel costs while improving traveler satisfaction.