30,284 research outputs found
"The Milk of Birds": A Proverbial Phrase, Ancient and Modern, and its Link to Nature
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
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
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
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.
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
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 () the eccentricity of the inner planet
can be in the range , the period and eccentricity of the
outer planet can be days and
respectively, while the relative pericenter alignment, , of the planets
can take essentially any value . It is
therefore difficult to determine whether and have evolved to
a fixed-point state or a limit cycle, or to use to probe the
internal planetary structure. We perform various transit timing variation (TTV)
analyses, demonstrating that current constraints merely restrict
, and rule out relative planetary inclinations within of , 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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