31,065 research outputs found
What works and for whom: a review of OECD countries' experiences with active labour market policies
Although rather discouraging in general, the evaluation literature indicates some measures that have been successful. Job-search assistance, wage subsidies in the private sector, and labour market training do work for some groups, even if the impacts are not large. Also, the evaluation literature focuses on the impacts of one-off programs. Regular interventions, such as job-search monitoring, intensive interviews, and referrals to vacant jobs, have rarely been evaluated rigorously. Recently, introduced "activation" strategies in some OECD countries do appear to yield significant employment gains for participants. An important element in such strategies is experiments with alternative ways of improving the performance of the public employment service. Activation policies which combine high-quality assistance to find work with pressure on unemployed people to accept job offers can be effective with respect to unemployment duration, but more rapid returns to work sometimes comes at the cost of accepting lower re-employment earnings. Although active policies might give rise to displacement effects in the short run, this need not be case the over the medium run of a few years. Declines in structural employment rates achieved by many OECD countries in the 1990s give some reasons for optimism in this respect.job search; wage subsidies; labour market training
Characterization and In-situ Monitoring of Sub-stoichiometric Adjustable Tc Titanium Nitride Growth
The structural and electrical properties of Ti-N films deposited by reactive
sputtering depend on their growth parameters, in particular the Ar:N2 gas
ratio. We show that the nitrogen percentage changes the crystallographic phase
of the film progressively from pure \alpha-Ti, through an \alpha-Ti phase with
interstitial nitrogen, to stoichiometric Ti2N, and through a substoichiometric
TiNX to stoichiometric TiN. These changes also affect the superconducting
transition temperature, Tc, allowing, the superconducting properties to be
tailored for specific applications. After decreasing from a Tc of 0.4 K for
pure Ti down to below 50 mK at the Ti2N point, the Tc then increases rapidly up
to nearly 5 K over a narrow range of nitrogen incorporation. This very sharp
increase of Tc makes it difficult to control the properties of the film from
wafer-to-wafer as well as across a given wafer to within acceptable margins for
device fabrication. Here we show that the nitrogen composition and hence the
superconductive properties are related to, and can be determined by,
spectroscopic ellipsometry. Therefore, this technique may be used for process
control and wafer screening prior to investing time in processing devices
Phosphorus and arsenic distributions in a seasonally-stratified, iron- and manganese-rich lake: microbiological and geochemical controls
Seasonal stratification in temperate lakes greater than a few metres deep provides conditions amenable to pronounced vertical zonation of redox chemistry. Such changes are particularly evident in eutrophic systems where high phytoplankton biomass often leads to seasonally-established anoxic hypolimnia and profound changes in geochemical conditions. In this study, we investigated the behaviour of trace elements in the water column of a seasonally-stratified, eutrophic lake. Two consecutive years of data from Lake Ngapouri, North Island, New Zealand, demonstrate the occurrence of highly correlated profiles of phosphorus (P), arsenic (As), iron (Fe) and manganese (Mn), all of which increased in concentration by 1-2 orders of magnitude within the anoxic hypolimnion. Stoichiometric and mass-balance considerations demonstrate that increases in alkalinity in hypolimnetic waters were consistent with observed changes in sulfate, Fe and Mn concentrations with depth, corresponding to dissimilatory reduction of sulfate, Fe(III) and Mn(IV) hydroxides. Thermodynamic constraints on Fe, Mn and Al solubility indicate that amorphous Fe(III), Mn(IV) hydroxides most probably controlled Fe and Mn in the surface mixed layer (~0 to 8 m) while Al(III) hydroxides were supersaturated throughout the entire system. Surface complexation modelling indicated that iron hydroxides (HFO) potentially dominated As speciation in the lake. It is likely that other colloidal phases such as allophanic clays also limited HPO42- activity, reducing competition for HAsO42- adsorption to iron hydroxides. This research highlights the coupling of P, As, Fe and Mn in Lake Ngapouri, and the apparent role of multiple colloidal phases in affecting P and As activity within overarching microbiological and geochemical processes
Methodology for bus layout for topological quantum error correcting codes
Most quantum computing architectures can be realized as two-dimensional
lattices of qubits that interact with each other. We take transmon qubits and
transmission line resonators as promising candidates for qubits and couplers;
we use them as basic building elements of a quantum code. We then propose a
simple framework to determine the optimal experimental layout to realize
quantum codes. We show that this engineering optimization problem can be
reduced to the solution of standard binary linear programs. While solving such
programs is a NP-hard problem, we propose a way to find scalable optimal
architectures that require solving the linear program for a restricted number
of qubits and couplers. We apply our methods to two celebrated quantum codes,
namely the surface code and the Fibonacci code.Comment: 11 pages, 12 figure
Identifying capacitive and inductive loss in lumped element superconducting hybrid titanium nitride/aluminum resonators
We present a method to systematically locate and extract capacitive and
inductive losses in superconducting resonators at microwave frequencies by use
of mixed-material, lumped element devices. In these devices, ultra-low loss
titanium nitride was progressively replaced with aluminum in the
inter-digitated capacitor and meandered inductor elements. By measuring the
power dependent loss at 50 mK as the Al-TiN fraction in each element is
increased, we find that at low electric field, i.e. in the single photon limit,
the loss is two level system in nature and is correlated with the amount of Al
capacitance rather than the Al inductance. In the high electric field limit,
the remaining loss is linearly related to the product of the Al area times its
inductance and is likely due to quasiparticles generated by stray radiation. At
elevated temperature, additional loss is correlated with the amount of Al in
the inductance, with a power independent TiN-Al interface loss term that
exponentially decreases as the temperature is reduced. The TiN-Al interface
loss is vanishingly small at the 50 mK base temperature.Comment: 10 pages, 5 figure
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