3,937 research outputs found
Modification of anatase TiO(001) surface electronic structure by Au impurity
We have used density functional theory calculations based on the projector
augmented wave method to investigate the electronic structure of
Au-incorporated anatase TiO(001) surface. Due to the coordination with
several level oxygens, Au atoms can be encapsulated inside TiO slab. Au is
adsorbed over the surface Ti--O bond, so called the bridge site on anatase
TiO(001)--11 surface. However, for 0.25 ML coverage, Au atoms
energetically prefer to stay at 0.64 {\AA} above the midpoint of the two
surface oxygens which is significantly closer to the surface layer. When
implanted inside the slab for full coverage, Au forms parallel metallic wires
inside TiO lattice where interlayer distances increase due to local
segregation. Au brings half-filled impurity states into the band gap leading to
metallization, in addition to other filled surface and impurity bands within
the gap. These Au-driven Fermi-level-pinning gap states are close to, or even
in some cases inside, the conduction band of the host slab. On the other hand,
if Au is substituted for the surface Ti atom, Fermi level falls lower in the
gap closer to the valence band top.Comment: 10 pages, 4 figure
Collider design issues based on proton-driven plasma wakefield acceleration
Recent simulations have shown that a high-energy proton bunch can excite
strong plasma wakefields and accelerate a bunch of electrons to the energy
frontier in a single stage of acceleration. It therefore paves the way towards
a compact future collider design using the proton beams from existing
high-energy proton machines, e.g. Tevatron or the LHC. This paper addresses
some key issues in designing a compact electron-positron linear collider and an
electron-proton collider based on existing CERN accelerator infrastructure
An collider based on proton-driven plasma wakefield acceleration
Recent simulations have shown that a high-energy proton bunch can excite
strong plasma wakefields and accelerate a bunch of electrons to the energy
frontier in a single stage of acceleration. This scheme could lead to a future
collider using the LHC for the proton beam and a compact electron
accelerator of length 170 m, producing electrons of energy up to 100 GeV. The
parameters of such a collider are discussed as well as conceptual layouts
within the CERN accelerator complex. The physics of plasma wakefield
acceleration will also be introduced, with the AWAKE experiment, a proof of
principle demonstration of proton-driven plasma wakefield acceleration, briefly
reviewed, as well as the physics possibilities of such an collider.Comment: 6 pages, 2 figures, to appear in the proceedings of the DIS 2014
Workshop, 28 April - 2 May, Warsaw, Polan
CP violating anomalous top-quark couplings at the LHC
We study the T odd correlations induced by CP violating anomalous top-quark
couplings at both production and decay level in the process gg --> t t_bar -->
(b mu+ nu_mu) (b_bar mu- nu_mu_bar). We consider several counting asymmetries
at the parton level and find the ones with the most sensitivity to each of
these anomalous couplings at the LHC.Comment: 14 LaTeX Pages, 1 EPS Figure, minor typos correcte
DFT study of noble metal impurities of TiO2(110)
Cataloged from PDF version of article.Atomic and electronic structures of TiO2(110) surface with possible adsorptional, substitutional and interstitial Au or Pt elemental impurities at full and one-sixth monolayer concentrations were investigated by density functional theory calculations using the projector augmented wave approach within the plane wave method. Relative thermodynamic stabilities of such phases have been discussed by means of their surface free energies. Our results suggest that tunable photocatalytic activity can be achieved on Pt atom admixed rutile (110) surface at low coverages
Ekonometrik modellerle enflasyon tahmini: Pakistan üzerine ampirik bir uygulama
This article aims at modeling and forecasting inflation in Pakistan. For this purpose a number of econometric approaches are implemented and their results are compared. In ARIMA models, adding additional lags for p and/or q necessarily reduced the sum of squares of the estimated residuals. When a model is estimated using lagged variables, some observations are lost. Results further indicate that the VAR models do not perform better than the ARIMA (2, 1, 2) models and, the two factor model with ARIMA (2, 1, 2) slightly performs better than the ARIMA (2, 1, 2). Although the study focuses on the problem of macroeconomic forecasting, the empirical results have more general implications for small scale macroeconometric models.Bu makale Pakistan’daki enflasyonu modellemeyi ve tahmin etmeyi amaçlamaktadır. Bunun için bir takım ekonometrik yaklaşımlar uygulanmış ve sonuçları karşılaştırılmıştır. ARIMA modellerinde p ve/veya q için fazladan gecikme eklenmesi, hesaplanan hata terimlerinin karelerinin toplamını her zaman azaltmadığı görülmüştür. Gecikmeli değerlerle bir model oluşturulduğunda ise bazı gözlemlerin kaybedildiği ortaya çıkmıştır. Sonuçlar ayrıca şunu göstermiştir ki VAR modelleri ARIMA (2,1,2) modellerinden daha iyi performans sergilememekte ve iki faktörlü ARIMA (2,1,2) modeli ARIMA (2,1,2) modelinden az da olsa daha iyi sonuçlar ortaya koymaktadır. Bu çalışma makroekonomik tahmin sorunu üzerine odaklanmasına rağmen elde edilen ampirik sonuçlar küçük ölçekli makro-ekonometrik modeller için daha genel implikasyonlar taşımaktadır
Forecasting Inflation Through Econometric Models : an Empirical Study on Pakistani Data
Bu makale Pakistan’daki enflasyonu modellemeyi ve tahmin etmeyi amaçlamaktadır. Bunun için bir takım ekonometrik yaklaşımlar uygulanmış ve sonuçları karşılaştırılmıştır. ARIMA modellerinde p ve/veya q için fazladan gecikme eklenmesi, hesaplanan hata terimlerinin karelerinin toplamını her zaman azaltmadığı görülmüştür. Gecikmeli değerlerle bir model oluşturulduğunda ise bazı gözlemlerin kaybedildiği ortaya çıkmıştır. Sonuçlar ayrıca şunu göstermiştir ki VAR modelleri ARIMA (2,1,2) modellerinden daha iyi performans sergilememekte ve iki faktörlü ARIMA (2,1,2) modeli ARIMA (2,1,2) modelinden az da olsa daha iyi sonuçlar ortaya koymaktadır. Bu çalışma makroekonomik tahmin sorunu üzerine odaklanmasına rağmen elde edilen ampirik sonuçlar küçük ölçekli makro-ekonometrik modeller için daha genel implikasyonlar taşımaktadır.This article aims at modeling and forecasting inflation in Pakistan. For this purpose a number of econometric approaches are implemented and their results are compared. In ARIMA models, adding additional lags for p and/or q necessarily reduced the sum of squares of the estimated residuals. When a model is estimated using lagged variables, some observations are lost. Results further indicate that the VAR models do not perform better than the ARIMA (2, 1, 2) models and, the two factor model with ARIMA (2, 1, 2) slightly performs better than the ARIMA (2, 1, 2). Although the study focuses on the problem of macroeconomic forecasting, the empirical results have more general implications for small scale macroeconometric models
Forecasting Inflation Through Econometric Models : an Empirical Study on Pakistani Data
Bu makale Pakistan’daki enflasyonu modellemeyi ve tahmin etmeyi amaçlamaktadır. Bunun için bir takım ekonometrik yaklaşımlar uygulanmış ve sonuçları karşılaştırılmıştır. ARIMA modellerinde p ve/veya q için fazladan gecikme eklenmesi, hesaplanan hata terimlerinin karelerinin toplamını her zaman azaltmadığı görülmüştür. Gecikmeli değerlerle bir model oluşturulduğunda ise bazı gözlemlerin kaybedildiği ortaya çıkmıştır. Sonuçlar ayrıca şunu göstermiştir ki VAR modelleri ARIMA (2,1,2) modellerinden daha iyi performans sergilememekte ve iki faktörlü ARIMA (2,1,2) modeli ARIMA (2,1,2) modelinden az da olsa daha iyi sonuçlar ortaya koymaktadır. Bu çalışma makroekonomik tahmin sorunu üzerine odaklanmasına rağmen elde edilen ampirik sonuçlar küçük ölçekli makro-ekonometrik modeller için daha genel implikasyonlar taşımaktadır.This article aims at modeling and forecasting inflation in Pakistan. For this purpose a number of econometric approaches are implemented and their results are compared. In ARIMA models, adding additional lags for p and/or q necessarily reduced the sum of squares of the estimated residuals. When a model is estimated using lagged variables, some observations are lost. Results further indicate that the VAR models do not perform better than the ARIMA (2, 1, 2) models and, the two factor model with ARIMA (2, 1, 2) slightly performs better than the ARIMA (2, 1, 2). Although the study focuses on the problem of macroeconomic forecasting, the empirical results have more general implications for small scale macroeconometric models
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