47,170 research outputs found
Dynamical Self-assembly during Colloidal Droplet Evaporation Studied by in situ Small Angle X-ray Scattering
The nucleation and growth kinetics of highly ordered nanocrystal
superlattices during the evaporation of nanocrystal colloidal droplets was
elucidated by in situ time resolved small-angle x-ray scattering. We
demonstrated for the first time that evaporation kinetics can affect the
dimensionality of the superlattices. The formation of two-dimensional
nanocrystal superlattices at the liquid-air interface of the droplet has an
exponential growth kinetics that originates from interface "crushing".Comment: 4 pages, 4 figure
Space photography and the exploration of Mars
A general exposition of the scientific potentialities and analytic framework of space photography is presented using the photography of Mars from flybys and orbiters as the principal example. Space photography is treated here as a communication process in which planetary scene information is communicated to the eye-brain receiver of earth-based interpreters. The salient parameters of this process are: (1) total information returned, (2) surface resolution, and (3) a priori knowledge regarding the planetary surface observed
Investigation of the Problems of Lunar and Planetary Exploration Annual Report, 1 Dec. 1964 - 30 Nov. 1965
Problems of lunar and planetary exploratio
On Morals, Markets, and Climate Change: Exploring Pope Francis’ Challenge
The relation between Culture and Business has caught researchers’ attention long ago; itis not hard to find studies relating to these topics. According to Hofstede et al. (2010, p.18), Hampden-Turner and Trompenaars (2012, p. 8), and Erez and Gati (2004, p. 5),culture can be defined in many levels, for example, organizational culture, and national culture. The field of Business also contains several disciplines, for example, International Business Management, Project Management, and Project Governance. However, not somany studies can be found studying the relation between National Culture and Project Governance; therefore, this study is focused on this relation.This study is designed following a qualitative approach in order to clarify the relation between National Culture and Project Governance Principles. Case studies are used targeting the IT industry of three countries, Spain, Sweden, and Taiwan. These cases also contain the classical theory of cultural dimensions from Hofstede. Hofstede’s dimensionsare Power Distance (PDI), Individualism vs. Collectivism (IDV), Uncertainty Avoidance(UAI), Masculinity vs. Femininity (MAS), Long-term Orientation (LTO), and Indulgencevs. Restraint (IDU). They are applied in this study for distinguishing the differences between countries. This study is also based on the definition of Project GovernancePrinciples from Garland (2009), Klakegg (2008), and Müller et al. (2013). ProjectGovernance Principles are split into two categories as well, hard/ structural principles andsoft/ behaviour principles.In order to clarify the link between National Culture and Project Governance Principles,this thesis’ authors interviewed 19 people, including 10 project managers and 9 experts.All of them have a long experience dealing with Project Management in the three selected countries. Their answers are based on the knowledge and experience of Project Management and Project Governance, as well as their opinions about their own national culture. After analysing the interviews, the authors consider that differences between these three countries in Project Governance and Project Governance Principles do exist. On the other hand, there are also some similar parts, for example, the influence ofcustomers’ orientation and preference. Moreover, respondents, Project Managers and Experts, all mentioned it is also necessary to be aware of the globalized environment, inother words, there is no influence of a single national culture in one country anymore.However, they all admit the importance of their own national culture as well. All these findings from this study encourage further and deeper study in the future
Patching task-level robot controllers based on a local µ-calculus formula
We present a method for mending strategies for
GR(1) specifications. Given the addition or removal of edges
from the game graph describing a problem (essentially transition
rules in a GR(1) specification), we apply a µ-calculus
formula to a neighborhood of states to obtain a “local strategy”
that navigates around the invalidated parts of an original
synthesized strategy. Our method may thus avoid global resynthesis
while recovering correctness with respect to the new
specification. We illustrate the results both in simulation and
on physical hardware for a planar robot surveillance task
The effect of small elongations on the electronic and optical signatures in InAs nanocrystal quantum dots
We present a detailed theoretical investigation of the electronic structure and
optical properties of InAs nanocrystals at the transition from spheres to rods. Using
a semiempirical pseudopotential approach, we predict that, despite the qualitative
similarity of both intra- and inter-band optical spectra, for NCs with R > 15 °A even
slight elongations should result in shifts of the order of hundreds of meV in the spacings
between STM peaks measured in the positive bias regime, in the position of the intra-
band absorption peaks associated with transitions in the conduction band and in the
separation between the first and the fifth peak in PLE experiments. Our results show
that, based on the spectroscopic data, it should be possible to discriminate between
spherical and elongated NCs with aspect ratios of length over diameter as small as
1.2. Indeed our results suggest that many nominally spherical experimental samples
contained a large fraction of slightly elongated structures
Are Stars with Planets Polluted?
We compare the metallicities of stars with radial velocity planets to the
metallicity of a sample of field dwarfs. We confirm recent work indicating that
the stars-with-planet sample as a whole is iron rich. However, the lowest mass
stars tend to be iron poor, with several having [Fe/H]<-0.2, demonstrating that
high metallicity is not required for the formation of short period Jupiter-mass
planets. We show that the average [Fe/H] increases with increasing stellar mass
(for masses below 1.25 solar masses) in both samples, but that the increase is
much more rapid in the stars-with-planet sample. The variation of metallicity
with stellar age also differs between the two samples. We examine possible
selection effects related to variations in the sensitivity of radial velocity
surveys with stellar mass and metallicity, and identify a color cutoff
(B-V>0.48) that contributes to but does not explain the mass-metallicity trend
in the stars-with-planets sample. We use Monte Carlo models to show that adding
an average of 6.5 Earth masses of iron to each star can explain both the
mass-metallicity and the age-metallicity relations of the stars-with-planets
sample. However, for at least one star, HD 38529, there is good evidence that
the bulk metallicity is high. We conclude that the observed metallicities and
metallicity trends are the result of the interaction of three effects;
accretion of about 6 Earth masses of iron rich material, selection effects, and
in some cases, high intrinsic metallicity.Comment: 19 pages 11 figure
Hydrodynamic modelling of accretion flows
In the proceedings of this, and of several recent close binary conferences,
there have been several contributions describing smoothed particle
hydrodynamics simulations of accretion disks. It is apposite therefore to
review the numerical scheme itself with emphasis on its advantages for disk
modelling, and the methods used for modelling viscous processes.Comment: 3 pages, to appear in proceedings of IAU Colloquium 194: Compact
binaries in the galaxy and beyon
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