8,151 research outputs found
Oil price shocks and policy uncertainty: New evidence on the effects of US and non-US oil production
Important interaction has been established for US economic policy uncertainty with a number of
economic and financial variables including oil prices. This paper examines the dynamic effects of
US and non-US oil production shocks on economic policy uncertainty using a structural VAR
model. Such an examination is motivated by the substantial increases in US oil production in recent
years with implications for US political and economic security. Positive innovations in US oil
production are associated with decreases in US economic policy uncertainty. The economic
forecast interquartile ranges about the US CPI and about federal/state/local government
expenditures are particularly sensitive to innovations in US oil supply shocks. Shocks to US oil
supply disruption causes rises in the CPI forecast uncertainty and accounts for 21% of the overall
variation of the CPI forecaster disagreement. Dis-aggregation of oil production shocks into US
and non-US oil production yield novel results. Oil supply shocks identified by US and non-US
origins explain as much of the variation in economic policy uncertainty as structural shocks on the
demand side of the oil market
Fabrication of (Ga,Mn)N nanowires with room temperature ferromagnetism using nitrogen plasma
Ferromagnetic properties of (Ga,Mn)N nanowires were examined by treating with nitrogen plasma at 200 ??C. Nanowires grown by chemical vapor deposition were n-type and no secondary phases were found. The magnetic moment increased and was maintained at room temperature by this treatment. Synchrotron radiation photoemission spectroscopy revealed that Ga vacancies significantly increased, but N vacancies decreased by plasma treatment, leading to a decrease of MnGa-VN complex and the enhancement of Mn activation.open111
Enhancement of magnetic properties by nitrogen implantation to Mn-implanted p-type GaN
N and Mn ions were co-implanted into p-type GaN and subsequently annealed at 700-900degreesC. Compared with Mn-implanted sample, the (Mn+N)-implanted sample revealed a larger ferromagnetic signal. This was attributed to the increase of Ga-Mn magnetic phases. Mn-N compounds, such as Mn6N2.58 and Mn3N2, decreased and the resistivity significantly increased, meaning a reduction of N vacancies. It is suggested that enhancement in ferromagnetic properties in the (Mn+N)-implanted GaN originated from the reduction of N vacancies and the increase of Ga-Mn magnetic phases.open293
Microstructural, optical, and magnetic properties of Mn-implanted p-type GaN
The microstructural, optical and magnetic properties of Mn-implanted p-type GaN were investigated. Dilute magnetic semiconductor was achieved by implanting Mn ions into p-type GaN and subsequently annealing. The Ga-Mn magnetic phases contributing to the ferromagnetic property were produced after annealing Mn-implanted p-type GaN below 800??C.open151
The Minimal Solution to the mu/B_mu Problem in Gauge Mediation
We provide a minimal solution to the mu/B_mu problem in the gauge mediated
supersymmetry breaking by introducing a Standard Model singlet filed S with a
mass around the messenger scale which couples to the Higgs and messenger
fields. This singlet is nearly supersymmetric and acquires a relatively small
Vacuum Expectation Value (VEV) from its radiatively generated tadpole term.
Consequently, both mu and B_mu parameters receive the tree-level and one-loop
contributions, which are comparable due to the small S VEV. Because there
exists a proper cancellation in such two kinds of contributions to B_mu, we can
have a viable Higgs sector for electroweak symmetry breaking.Comment: 15 pages, 2 figures, version published on JHE
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