7,358 research outputs found
Assessing narrative comprehension in young children
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/88014/1/RRQ.38.1.3.pd
Atmospheric studies of habitability in the Gliese 581 system
The M-type star Gliese 581 is orbited by at least one terrestrial planet
candidate in the habitable zone, i.e. GL 581 d. Orbital simulations have shown
that additional planets inside the habitable zone of GL 581 would be
dynamically stable. Recently, two further planet candidates have been claimed,
one of them in the habitable zone.
In view of the ongoing search for planets around M stars which is expected to
result in numerous detections of potentially habitable Super-Earths, we take
the GL 581 system as an example to investigate such planets. In contrast to
previous studies of habitability in the GL 581 system, we use a consistent
atmospheric model to assess surface conditions and habitability. Furthermore,
we perform detailed atmospheric simulations for a much larger subset of
potential planetary and atmospheric scenarios than previously considered.
A 1D radiative-convective atmosphere model is used to calculate temperature
and pressure profiles of model atmospheres, which we assumed to be composed of
molecular nitrogen, water, and carbon dioxide. In these calculations, key
parameters such as surface pressure and CO2 concentration as well as orbital
distance and planetary mass are varied.
Results imply that surface temperatures above freezing could be obtained,
independent of the here considered atmospheric scenarios, at an orbital
distance of 0.117 AU. For an orbital distance of 0.146 AU, CO2 concentrations
as low as 10 times the present Earth's value are sufficient to warm the surface
above the freezing point of water. At 0.175 AU, only scenarios with CO2
concentrations of 5% and 95% were found to be habitable. Hence, an additional
Super-Earth planet in the GL 581 system in the previously determined dynamical
stability range would be considered a potentially habitable planet.Comment: 5 pages, 4 figures, accepted in Astronomy&Astrophysic
Hanging out on Snapchat: disrupting passive covert netnography in tourism research
Tourism research is increasingly turning to online social media conversations as a data source, but seldom assigning space in research outputs for ethical appraisals or reflexive accounts of data collection. Many tourism researchers download conversations after they have occurred, but presence is central to gaining rich insights through netnographic research. We contribute to and disrupt online tourism research by critiquing, extending, and adapting existing methods to Snapchat, which in itself disrupts possibilities for online data collection. Hanging out with tourist Snapchatters highlights how privacy concerns are a primary motive to post on Snapchat. Snapchat is understood by our participants as more private than other social media sites due to the ephemerality of content and the notification of screenshots (when others save your snap). It is no coincidence that these same functionalities render established methods of digital tourism research difficult in the case of Snapchat. Snapchat users also problematise the notion of social media as public space, as they utilise the platforms for much more than communicating with the world. Snapchatters create, augment, and store memories
Special issue "The past and present threat of rickettsial diseases"
Historically, the rickettsioses have a track record of making substantial impact on mankind in military activities and international public health over the past centuries [...]
A gender analysis of intercultural sensitivity among flight attendants
Due to the nature of gender as a social construct, it is commonly believed that women are more sensitive than men and are therefore more suited to certain employment positions, such as those customer facing roles in the hospitality industry. Little empirical evidence supports this idea, but this commonly held assumption may be part of the reason why flight attendants are predominantly women. To test intercultural sensitivity between women and men flight attendants, this paper explored intercultural sensitivity in a sample of 204 flight attendants in the Middle East. According to the results, women expressed more intercultural sensitivity in four out of five factors. These findings should help airlines design training for flight attendants, where they may have to undo gender
Stationary entanglement in N-atom subradiant degenerate cascade systems
We address ultracold -atom degenerate cascade systems and show that
stationary subradiant states, already observed in the semiclassical regime,
also exist in a fully quantum regime and for a small number of atoms. We
explicitly evaluate the amount of stationary entanglement for the two-atom
configuration and show full inseparability for the three-atom case. We also
show that a continuous variable description of the systems is not suitable to
detect entanglement due to the nonGaussianity of subradiant states.Comment: 4 figure
Let’s Sit at the Table for women’s empowerment
We report on Let’s Sit at the Table, an ongoing series of seven (so far) roundtables launched in partnership by the Dubai based social enterprise Evolvin' Women and The Retreat Palm Dubai MGallery by Sofitel in September 2017. The roundtables were designed to explore best practices in the Gulf region driving women within the hospitality industry to senior leadership positions. Here we focus on one of the roundtables, which took place on February 21st, 2018 and was centered on the topic of empowering women in hospitality through education. The roundtable explored how to encourage women and girls to take up positions in fields where they lack representation, such as in the culinary arts. The roundtable was attended by ten experts in the areas of education and hospitality and revolved around several questions developed in line with the UN's Women Empowerment Principles (http://www.weprinciples.org/). To encourage further research we first briefly describe the problem as acknowledged in the academic literature and as experienced by one social enterprise in Dubai
Two quantum Simpson's paradoxes
The so-called Simpson's "paradox", or Yule-Simpson (YS) effect, occurs in
classical statistics when the correlations that are present among different
sets of samples are reversed if the sets are combined together, thus ignoring
one or more lurking variables. Here we illustrate the occurrence of two
analogue effects in quantum measurements. The first, which we term
quantum-classical YS effect, may occur with quantum limited measurements and
with lurking variables coming from the mixing of states, whereas the second,
here referred to as quantum-quantum YS effect, may take place when coherent
superpositions of quantum states are allowed. By analyzing quantum measurements
on low dimensional systems (qubits and qutrits), we show that the two effects
may occur independently, and that the quantum-quantum YS effect is more likely
to occur than the corresponding quantum-classical one. We also found that there
exist classes of superposition states for which the quantum-classical YS effect
cannot occur for any measurement and, at the same time, the quantum-quantum YS
effect takes place in a consistent fraction of the possible measurement
settings. The occurrence of the effect in the presence of partial coherence is
discussed as well as its possible implications for quantum hypothesis testing.Comment: published versio
Quantum probes for the cutoff frequency of Ohmic environments
Quantum probing consists of suitably exploiting a simple, small, and
controllable quantum system to characterize a larger and more complex system.
Here, we address the estimation of the cutoff frequency of the Ohmic spectral
density of a harmonic reservoir by quantum probes. To this aim, we address the
use of single-qubit and two-qubit systems and different kinds of coupling with
the bath of oscillators. We assess the estimation precision by the quantum
Fisher information of the sole quantum probe as well as the corresponding
quantum signal-to-noise ratio. We prove that, for most of the values of the
Ohmicity parameter, a simple probe such as a single qubit is already optimal
for the precise estimation of the cutoff frequency. Indeed for those values,
upon considering a two-qubit probe either in a Bell or in separable state, we
do not find improvement to the estimation precision. However, we also showed
that there exist few conditions where employing two qubits in a Bell state
interacting with a common bath is more suitable for precisely estimating the
cutoff frequency.Comment: 8 pages, 5 figures, 1 tabl
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