6,618 research outputs found
On the Impact of the Global Financial Crisis on the Euro Area
This paper analyses the impact of the Global Financial Crisis on the Euro area utilizing a simple dynamic macroeconomic model with interaction between monetary policy and �fiscal policy. The model consists of an IS curve, a Phillips curve, a term structure relation, a debt
accumulation equation and a Taylor monetary policy rule supplemented with a Zero Lower Bound, and a fi�scal policy rule. The model is calibrated/estimated for EU-16 countries
for the period 1980Q1{2009Q4. The impact of the Global Financial Crisis is studied by means of impulse responses following a combined, prolonged aggregate demand and public
debt shock. The simulation mimicking the GFC turns out to work fairly well. However, the required size of the shock is quite large
Floppy modes and the free energy: Rigidity and connectivity percolation on Bethe Lattices
We show that negative of the number of floppy modes behaves as a free energy
for both connectivity and rigidity percolation, and we illustrate this result
using Bethe lattices. The rigidity transition on Bethe lattices is found to be
first order at a bond concentration close to that predicted by Maxwell
constraint counting. We calculate the probability of a bond being on the
infinite cluster and also on the overconstrained part of the infinite cluster,
and show how a specific heat can be defined as the second derivative of the
free energy. We demonstrate that the Bethe lattice solution is equivalent to
that of the random bond model, where points are joined randomly (with equal
probability at all length scales) to have a given coordination, and then
subsequently bonds are randomly removed.Comment: RevTeX 11 pages + epsfig embedded figures. Submitted to Phys. Rev.
Onset of rigidty in glasses: from random to self-organized networks
We review in this paper the signatures of a new elastic phase that is found
in glasses with selected compositions. It is shown that in contrast with random
networks, where rigidity percolates at a single threshold, networks that are
able to self-organize to avoid stress will remain in an almost stress- free
state during a compositional interval, an intermediate phase, that is bounded
by a flexible phase and a stressed rigid phase. We report the experimental
signatures and describe the theoretical efforts that have been accomplished to
characterize the intermediate phase. We illustrate one of the methods used in
more detail with the example of Group III chalcogenides and finally suggest
further possible experimental signatures of self-organization.Comment: 27 pages, 6 figures, Proceedings of the Conference on Non-Crystalline
Materials 10, to appear in Journal of Non-Crystalline Solid
Advances in Microfluidics and Lab-on-a-Chip Technologies
Advances in molecular biology are enabling rapid and efficient analyses for
effective intervention in domains such as biology research, infectious disease
management, food safety, and biodefense. The emergence of microfluidics and
nanotechnologies has enabled both new capabilities and instrument sizes
practical for point-of-care. It has also introduced new functionality, enhanced
sensitivity, and reduced the time and cost involved in conventional molecular
diagnostic techniques. This chapter reviews the application of microfluidics
for molecular diagnostics methods such as nucleic acid amplification,
next-generation sequencing, high resolution melting analysis, cytogenetics,
protein detection and analysis, and cell sorting. We also review microfluidic
sample preparation platforms applied to molecular diagnostics and targeted to
sample-in, answer-out capabilities
Geophysical studies with laser-beam detectors of gravitational waves
The existing high technology laser-beam detectors of gravitational waves may
find very useful applications in an unexpected area - geophysics. To make
possible the detection of weak gravitational waves in the region of high
frequencies of astrophysical interest, ~ 30 - 10^3 Hz, control systems of laser
interferometers must permanently monitor, record and compensate much larger
external interventions that take place in the region of low frequencies of
geophysical interest, ~ 10^{-5} - 3 X 10^{-3} Hz. Such phenomena as tidal
perturbations of land and gravity, normal mode oscillations of Earth,
oscillations of the inner core of Earth, etc. will inevitably affect the
performance of the interferometers and, therefore, the information about them
will be stored in the data of control systems. We specifically identify the
low-frequency information contained in distances between the interferometer
mirrors (deformation of Earth) and angles between the mirrors' suspensions
(deviations of local gravity vectors and plumb lines). We show that the access
to the angular information may require some modest amendments to the optical
scheme of the interferometers, and we suggest the ways of doing that. The
detailed evaluation of environmental and instrumental noises indicates that
they will not prevent, even if only marginally, the detection of interesting
geophysical phenomena. Gravitational-wave instruments seem to be capable of
reaching, as a by-product of their continuous operation, very ambitious
geophysical goals, such as observation of the Earth's inner core oscillations.Comment: 29 pages including 8 figures, modifications and clarifications in
response to referees' comments, to be published in Class. Quant. Gra
The development of a municipal water conservation and demand management strategy and business plan as required by the Water Services Act, South Africa
The implementation of water conservation and water demand management (WC/WDM) at municipal level has been inadequate for many years, despite South Africa being one of the driest countries in the world. This could be attributed to a lack of planning, and not realising the consequences and potential benefits of water restrictions. Many South African municipalities do not have a WC/WDM strategy and business plan although many books, publications and software packages have been produced to assist water supply managers. Most of the existing strategies are also vague and of little value, and the municipalities do not have the necessary financial, technical and institutional capacity to support such a strategy. Municipalities often fail to realise that most WC/WDM activities will pay for themselves and that financial institutions will fund these projects if a proper business case could be compiled. Ironically municipalities have complained that they are unable to obtain funding while most financial institutions complain that they cannot find bankable projects because of the poor quality of the applications and strategies. This guideline provides a simple and pragmatic approach to the development of a WC/WDM strategy and business plan which will enable municipalities to plan, obtain funding, implement and ensure the overall sustainability of water resources in the municipality and the country as a whole.Keywords: water conservation, demand managemen
Melt homogenization and self-organization of chalcogenides glasses: evidence of sharp rigidity, stress and nanoscale phase separation transitions in the GexSe100-x binary
A Raman profiling method is used to monitor growth of GexSe100-x melts and
reveals a two step process of homogenization. Resulting homogeneous glasses
show the non-reversing enthalpy at Tg, {\Delta}Hnr(x), to show a square-well
like variation with x, with a rigidity transition near xc(1) = 19.5(5)% and
stress transition near xc(2) = 26.0(5)%) representing the boundaries of the
rigid but stress-free Intermediate Phase (IP). The square-well like variation
of {\Delta}Hnr(x) develops sloping walls, a triangular shape and eventually
disappears in glasses having an increasing heterogeneity. The {\Delta}Hnr term
ages over weeks outside the IP but not inside the IP. An optical analogue of
the reversibility window is observed with Raman spectra of as-quenched melts
and Tg cycled glasses being the same for glass compositions in the IP but
different for compositions outside the IP. Variations of Molar volumes, display
three regimes of behavior with a global minimum in the IP and a pronounced
increase outside that phase. The intrinsic physical behavior of dry and
homogeneous chalcogenides glasses can vary sharply with composition near
elastic and chemical phase transitions, showing that the physics of network
glasses requires homogeneous samples, and may be far more interesting than
hitherto recognized
Evaluation of minimum residual pressure as design criterion for South African water distribution systems
The South African civil engineering fraternity has grown to accept 24 m as the design criterion for minimum residual pressure in water distribution systems. However, the theoretical peak demand in many systems has increased beyond the point where minimum residual pressure exceeds 24 m – at least according to hydraulic models. Additions of customers to existing supply systems have led to increased peak flows with time, often without infrastructure upgrades to internal reticulation. Increased flows imply reduced pressures. This is not necessarily a concern: peak flow conditions rarely occur in a supply system and also, customer complaints often act as a first sign of ‘low pressures’. No complaints imply ‘no low pressures’. The researchers analysed hydraulic models for 14 different towns in 5 municipal areas of South Africa, including 2 large metros,to identify the minimum residual pressures currently expected. The results include almost 55 000 model nodes and show that about 20% of the nodes in the distribution systems analysed have pressures of below 24 m, while pressures of below 14 m are not uncommon. Whether this relatively common occurrence of low pressures under modelled peak demand is found in practice is not known at this stage. A new guideline for minimum residual pressure based on previous criteria and results from this study is presented, noting that a physical lower limit of about 10 m water pressure is specified in home appliance specifications
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