881 research outputs found
The effects of the underground economy on economic competitiviness
A real, almost palpable, connection exists between the official and the underground economy. More than that, both sides of the economy (official and underground) are connected with the competitiveness of a country. Strangely a large presence of undereground in the economy is a sign of competitiveness. Although we would be tempted to say that underground is bad for competitiveness the reality is that due to taxes and regulations the resources (especially the human ones) used ”illegaly” would probably be wasted. In the end the wages from the underground economy return to the oficial one suporting it and hence the competitiveness of the country.official economy; underground economy; illegal activities; tax evasion; economic competitiveness
The effects of the underground economy on economic competitiviness
A real, almost palpable, connection exists between the official and the underground economy. More than that, both sides of the economy (official and underground) are connected with the competitiveness of a country. Strangely a large presence of undereground in the economy is a sign of competitiveness. Although we would be tempted to say that underground is bad for competitiveness the reality is that due to taxes and regulations the resources (especially the human ones) used ”illegaly” would probably be wasted. In the end the wages from the underground economy return to the oficial one suporting it and hence the competitiveness of the country
Systems of subspaces of a unitary space
For a given poset, we consider its representations by systems of subspaces of
a unitary space ordered by inclusion. We classify such systems for all posets
for which an explicit classification is possible.Comment: 20 page
Quantum Holographic Encoding in a Two-dimensional Electron Gas
The advent of bottom-up atomic manipulation heralded a new horizon for
attainable information density, as it allowed a bit of information to be
represented by a single atom. The discrete spacing between atoms in condensed
matter has thus set a rigid limit on the maximum possible information density.
While modern technologies are still far from this scale, all theoretical
downscaling of devices terminates at this spatial limit. Here, however, we
break this barrier with electronic quantum encoding scaled to subatomic
densities. We use atomic manipulation to first construct open
nanostructures--"molecular holograms"--which in turn concentrate information
into a medium free of lattice constraints: the quantum states of a
two-dimensional degenerate Fermi gas of electrons. The information embedded in
the holograms is transcoded at even smaller length scales into an atomically
uniform area of a copper surface, where it is densely projected into both two
spatial degrees of freedom and a third holographic dimension mapped to energy.
In analogy to optical volume holography, this requires precise amplitude and
phase engineering of electron wavefunctions to assemble pages of information
volumetrically. This data is read out by mapping the energy-resolved electron
density of states with a scanning tunnelling microscope. As the projection and
readout are both extremely near-field, and because we use native quantum states
rather than an external beam, we are not limited by lensing or collimation and
can create electronically projected objects with features as small as ~0.3 nm.
These techniques reach unprecedented densities exceeding 20 bits/nm2 and place
tens of bits into a single fermionic state.Comment: Published online 25 January 2009 in Nature Nanotechnology; 12 page
manuscript (including 4 figures) + 2 page supplement (including 1 figure);
supplementary movie available at http://mota.stanford.ed
Auto-proteção profissional e cuidado de enfermagem ao paciente soropositivo ao HIV: duas facetas de uma representação
Single nucleotide polymorphisms and breast cancer: not yet a success story
Numerous studies have examined low penetrance susceptibility polymorphisms in candidate genes, with some reporting significant findings. However, for the most part these associations could not be replicated in subsequent studies, suggesting that the original observations were due to chance. The failure to identify meaningful common genetic variation in relation to breast cancer should give us pause for thought and make us reconsider our current research strategies. The most recent directions of pooling samples to increase statistical power and pursuing whole genome screens may overcome some obstacles while also creating new challenges. Future studies should perhaps also consider alternative designs such as using surrogate (preferably continuous) markers of breast cancer, focusing on high-risk populations, and defining pathologically distinct outcomes
Single nucleotide polymorphisms and breast cancer: not yet a success story
Numerous studies have examined low penetrance susceptibility polymorphisms in candidate genes, with some reporting significant findings. However, for the most part these associations could not be replicated in subsequent studies, suggesting that the original observations were due to chance. The failure to identify meaningful common genetic variation in relation to breast cancer should give us pause for thought and make us reconsider our current research strategies. The most recent directions of pooling samples to increase statistical power and pursuing whole genome screens may overcome some obstacles while also creating new challenges. Future studies should perhaps also consider alternative designs such as using surrogate (preferably continuous) markers of breast cancer, focusing on high-risk populations, and defining pathologically distinct outcomes
Recommended from our members
The poleward migration of the location of tropical cyclone maximum intensity
Temporally inconsistent and potentially unreliable global historical data hinder the detection of trends in tropical cyclone activity. This limits our confidence in evaluating proposed linkages between observed trends in tropical cyclones and in the environment. Here we mitigate this difficulty by focusing on a metric that is comparatively insensitive to past data uncertainty, and identify a pronounced poleward migration in the average latitude at which tropical cyclones have achieved their lifetime-maximum intensity over the past 30 years. The poleward trends are evident in the global historical data in both the Northern and the Southern hemispheres, with rates of 53 and 62 kilometres per decade, respectively, and are statistically significant. When considered together, the trends in each hemisphere depict a global-average migration of tropical cyclone activity away from the tropics at a rate of about one degree of latitude per decade, which lies within the range of estimates of the observed expansion of the tropics over the same period. The global migration remains evident and statistically significant under a formal data homogenization procedure, and is unlikely to be a data artefact. The migration away from the tropics is apparently linked to marked changes in the mean meridional structure of environmental vertical wind shear and potential intensity, and can plausibly be linked to tropical expansion, which is thought to have anthropogenic contributions
LEMUR: Large European Module for solar Ultraviolet Research. European contribution to JAXA's Solar-C mission
Understanding the solar outer atmosphere requires concerted, simultaneous
solar observations from the visible to the vacuum ultraviolet (VUV) and soft
X-rays, at high spatial resolution (between 0.1" and 0.3"), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK, from the
chromosphere to the flaring corona), and the capability of measuring magnetic
fields through spectropolarimetry at visible and near-infrared wavelengths.
Simultaneous spectroscopic measurements sampling the entire temperature range
are particularly important.
These requirements are fulfilled by the Japanese Solar-C mission (Plan B),
composed of a spacecraft in a geosynchronous orbit with a payload providing a
significant improvement of imaging and spectropolarimetric capabilities in the
UV, visible, and near-infrared with respect to what is available today and
foreseen in the near future.
The Large European Module for solar Ultraviolet Research (LEMUR), described
in this paper, is a large VUV telescope feeding a scientific payload of
high-resolution imaging spectrographs and cameras. LEMUR consists of two major
components: a VUV solar telescope with a 30 cm diameter mirror and a focal
length of 3.6 m, and a focal-plane package composed of VUV spectrometers
covering six carefully chosen wavelength ranges between 17 and 127 nm. The
LEMUR slit covers 280" on the Sun with 0.14" per pixel sampling. In addition,
LEMUR is capable of measuring mass flows velocities (line shifts) down to 2
km/s or better.
LEMUR has been proposed to ESA as the European contribution to the Solar C
mission.Comment: 35 pages, 14 figures. To appear on Experimental Astronom
- …