29,943 research outputs found

    "The Milk of Birds": A Proverbial Phrase, Ancient and Modern, and its Link to Nature

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    A curious phrase from ancient Greek, ὀρνίθων γάλα, finds parallels in Latin as lac gallinaceum and in Modern Greek, as και του πουλιού το γάλα. While the Greek phrases translate as "(and) the milk of (the) bird(s)", the Latin translates as "henʼs milk". This essay discusses the phrase in a select variety of Greek and Latin sources from the 5th century BCE to the 4th century CE, and its Modern Greek equivalent in the 21st century. In addition, it discusses the variety of meanings and uses found in those sources, and connections to the natural world. Information from ancient sources has been gleaned from a search of the Digital Loeb Classical Library online database. Information for modern use comes from informal interviews, Facebook messages, e-mails, and telephone messages of nine native speakers of Modern Greek from different parts of the Greek world, most of whom live in the United States. The essay discusses two points concerning the natural world: first, the phrase as found in the names of certain plants, and second, as a substance called crop-milk produced by members of the pigeon family. The linguistic connection between ancient and modern worlds and the parallels found in nature encourage scholars to look "outside the box" when investigating proverbs, proverbial expressions and proverbial phrases. The Modern Greek version of the phrase both confirms and expands the meanings of the ancient ones, thus suggesting that other connections between these ancient and modern languages may prove to be fruitful avenues of investigation.

    The critical currents in superconducting tin films

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    The nonlinear current-voltage curves exhibited by tin films in the flux flow state have made studies of the amount of heating present in the sample necessary. The samples in this work consisted of an evaporated tin film on one side of a 2 mm thick crystal quartz substrate and a carbon film of the same configuration as the tin film on the back of the substrate. The carbon film was used as a thermometer to measure the temperature rise of the tin film above the bath temperature. The heating results indicate negligible effects in the samples. Temperature ratios as small as 0.80 for the tin samples have been investigated and the current-voltage characteristics are still nonlinear, indicating that the source of the nonlinearity is not Joule heating in the samples

    Electron cloud observations at the ISIS Proton Synchrotron

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    The build up of electron clouds inside a particle accelerator vacuum chamber can produce strong transverse and longitudinal beam instabilities which in turn can lead to high levels of beam loss often requiring the accelerator to be run below its design specification. To study the behaviour of electron clouds at the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud detector has been developed. The detector is based on the Retarding Field Analyser (RFA) design and consists of a retarding grid, which allows energy analysis of the electron signal, and a MCP assembly placed in front of the collector plate. The MCP assembly provides a current gain over the range 300 to 25K, thereby increasing the signal to noise ratio and dynamic range of the measurements. This paper presents the first electron cloud observations at the ISIS Proton Synchrotron. These results are compared against signals from a beam position monitor and a fast beam loss monitor installed at the same location.Comment: 4 pages, contribution to the Joint INFN-CERN-EuCARD-AccNet Workshop on Electron-Cloud Effects: ECLOUD'12; 5-9 Jun 2012, La Biodola, Isola d'Elba, Ital

    The potential for Earth-mass planet formation around brown dwarfs

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    Recent observations point to the presence of structured dust grains in the discs surrounding young brown dwarfs, thus implying that the first stages of planet formation take place also in the sub-stellar regime. Here, we investigate the potential for planet formation around brown dwarfs and very low mass stars according to the sequential core accretion model of planet formation. We find that, for a brown dwarfs of mass 0.05M_{\odot}, our models predict a maximum planetary mass of ~5M_{\oplus}, orbiting with semi-major axis ~1AU. However, we note that the predictions for the mass - semi-major axis distribution are strongly dependent upon the models chosen for the disc surface density profiles and the assumed distribution of disc masses. In particular, if brown dwarf disc masses are of the order of a few Jupiter masses, Earth-mass planets might be relatively frequent, while if typical disc masses are only a fraction of Jupiter mass, we predict that planet formation would be extremely rare in the sub-stellar regime. As the observational constraints on disc profiles, mass dependencies and their distributions are poor in the brown dwarf regime, we advise caution in validating theoretical models only on stars similar to the Sun and emphasise the need for observational data on planetary systems around a wide range of stellar masses. We also find that, unlike the situation around solar-like stars, Type-II migration is totally absent from the planet formation process around brown dwarfs, suggesting that any future observations of planets around brown dwarfs would provide a direct measure of the role of other types of migration.Comment: 11 pages, accepted for publication in MNRA

    Understanding residents’ capacities to support evacuated populations : A study of earthquake and tsunami evacuation for Napier Hill, Napier, Aotearoa New Zealand.

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    Due to a large regional subduction zone (the Hikurangi subduction zone) and localised faults, Napier City located on the East Coast of Aotearoa/New Zealand is vulnerable to earthquake and tsunami events. On feeling a long or strong earthquake people will need to evacuate immediately inland or to higher ground to avoid being impacted by a tsunami, of which the first waves could start to arrive within 20 minutes (based on the Hikurangi earthquake and tsunami scenario presented in Power et al., 2018). Napier Hill is one such area of higher land, and it is estimated that up to 12,000 people could evacuate there in the 20 minutes following a long or strong earthquake. To understand the capacity of Napier Hill residents to support evacuees, three focus groups were held with a diverse sample of residents from Napier Hill on 21 and 22 July 2019. A follow up email was sent to all participants a week after the focus groups, containing a link to a short six question survey, which was completed by 68 people, most of whom were additional to the focus group attendees. Data from the focus groups and the survey was analysed qualitatively using thematic analysis. The findings highlight that in general people were happy to host evacuees and offer support if they were in a position to do so. However, key issues in being able to offer support included the likely lack of resources available after a disaster, ranging from basic needs though to agency support. The research findings will directly inform Napier City Council and Hawke’s Bay Civil Defence Emergency Management Group’s planning for future readiness and response by providing valuable insights for evacuation planningfalseWellingtonHawke's Bay Civil Defence Emergency Management Grou

    An Analysis of Jitter and Transit Timing Variations in the HAT-P-13 System

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    If the two planets in the HAT-P-13 system are coplanar, the orbital states provide a probe of the internal planetary structure. Previous analyses of radial velocity and transit timing data of the system suggested that the observational constraints on the orbital states were rather small. We reanalyze the available data, treating the jitter as an unknown MCMC parameter, and find that a wide range of jitter values are plausible, hence the system parameters are less well constrained than previously suggested. For slightly increased levels of jitter (4.5ms1\sim 4.5\,m\,s^{-1}) the eccentricity of the inner planet can be in the range 0<einner<0.070<e_{inner}<0.07, the period and eccentricity of the outer planet can be 440<Pouter<470440<P_{outer}<470 days and 0.55<eouter<0.850.55<e_{outer}<0.85 respectively, while the relative pericenter alignment, η\eta, of the planets can take essentially any value 180<η<+180-180^{\circ}<\eta<+180^{\circ}. It is therefore difficult to determine whether einnere_{inner} and η\eta have evolved to a fixed-point state or a limit cycle, or to use einnere_{inner} to probe the internal planetary structure. We perform various transit timing variation (TTV) analyses, demonstrating that current constraints merely restrict eouter<0.85e_{outer}<0.85, and rule out relative planetary inclinations within 2\sim 2^{\circ} of irel=90i_{rel}=90^{\circ}, but that future observations could significantly tighten the restriction on both these parameters. We demonstrate that TTV profiles can readily distinguish the theoretically favored inclinations of i_{rel}=0^{\circ}\,&\,45^{\circ}, provided that sufficiently precise and frequent transit timing observations of HAT-P-13b can be made close to the pericenter passage of HAT-P-13c. We note the relatively high probability that HAT-P-13c transits and suggest observational dates and strategies.Comment: Published in Ap
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