Bilateral J-Curves between Pakistan and Her Trading Partners

Earlier studies that investigated the J-Curve phenomenon for Pakistan employed aggregate trade data. These studies suffered from the “aggregation bias” problem. In order to overcome this constraint, this paper tests the effects of real exchange rate depreciation in the Pakistani Rupee on the bilateral trade balance between Pakistan and her 12 respective trade partners. These countries, together, account for almost half of Pakistan’s total trade. In order to differentiate between the long-run equilibrium and short-run disequilibrium dynamics, and also to deal with non-stationary data, the ARDL approach is used. The results do not provide any support for the standard J-curve phenomenon.J-Curve, Trade Balance, Marshall-Lerner Condition

Fermi surfaces and Phase Stability of Ba(Fe1−x_{1-x}Mx_x)2_2As2_2 (M=Co, Ni, Cu, Zn)

BaFe$_2$As$_2$ with transition-metal doping exhibits a variety of rich phenomenon from coupling of structure, magnetism, and superconductivity. Using density functional theory, we systematically compare the Fermi surfaces (FS), formation energies ($\Delta E_f$), and density of states (DOS) of electron-doped Ba(Fe$_{1-x}$M$_x$)$_2$As$_2$ with M={Co, Ni, Cu, Zn} in tetragonal (I$4/mmm$) and orthorhombic (F$mmm$) structures in nonmagnetic (NM), antiferromagnetic (AFM), and paramagnetic (PM, disordered local moment) states. We explain changes to phase stability ($\Delta E_f$) and Fermi surfaces (and nesting) due to chemical and magnetic disorder, and compare to observed/assessed properties and contrast alloy theory with that expected from rigid-band model. With alloying, the DOS changes from common-band (Co,Ni) to split-band (Cu,Zn), which dictates $\Delta E_f$ and can overwhelm FS-nesting instabilities, as for Cu,Zn cases

Fiber-reinforced composite with interpenetrating polymer network - Influence of shelf-life of the prepreg and the adhesive primer on interfacial adhesive strength of the composite to a resin luting material

Fiber-reinforced composite (FRC) is a low-cost metal-free restorative alternative. To overcome problems related to the interfacial adhesion between composite luting material and FRC, a semi-interpenetrating polymer network (semi-IPN) matrix with linear polymer of poly(methylmethacrylate) (PMMA) was developed for FRC. Therefore, a series of laboratory studies were executed to investigate the effect of shelf-life, monomer systems and PMMA gradient on the intact and ground substrates of semi-IPN FRC. In the four experimental studies, everStick C&B was used as the semi-IPN based FRC. The first study evaluated the shelf-life and dissolving capability of the methyl methacrylate (MMA) monomer in polymerized FRC. The second study investigated the effect of different adhesive/primer on polymerized FRC which were stored for various durations (at 4°C; 1.0, 1.5, and 3-year) before curing. The third study analyzed the tensile bond strength (TBS) between resin luting material and FRC using different adhesive/primers systems. The fourth study determined TBS between polymerized FRC intact (high gradient PMMA) or ground (low gradient PMMA) surfaces and a resin luting material. The results were statistically analyzed using analysis of variance (ANOVA), the post hoc Tukey’s test, regression and correlation analysis using statistical software. It can be concluded that upon aging, the linear and cross-linked components of the semi-IPN structure of FRC might become phase-segregated. Both G-Multi PRIMER and Composite Primer might have the ability to diffuse into polymerized FRC and form a durable adhesive layer with increased nanohardness and adhesive strength between resin luting material and the FRC substrate. The highest TBS can be achieved for FRC intact surface treated with the G-Multi PRIMER.Osittaislomittaismuoviverkostorakenne kuitulujitteissa muovissa – muovin esivalmisteen säilytysajan ja pinnan esikäsittelyajan vaikutus muovin rajapintaliitoksen sidoslujuuteen. Kuitulujittenen muovi on hammashoidon materiaali, joka täyttää hammaslääketieteen asettamat ulkonäölliset ja lujuusvaatimukset. Kuitulujitteinen muovi koostuu lujitekuiduista ja niitä sitovasta yleensä ristisilloitetusta muovimatriisista, joka voi olla myös osittaislomittaisverkostomuovirakenne (engl. semi-IPN). Tässä tutkimuksessa selvitettiin kuitulujite-esivalmisteen säilytysajan ja kovetetun kuitulujiteteisen muovin pinnan esikäsittelyn vaikutusta muovin liimautumiseen muihin hammaslääketieteessä käytettyihin muoveihin. Tutkimuksessa käytettiin semi-IPN muovipitoista kuitulujitteista muovia. Kuitulujitteisen muovin pinnan rakennetta ja ominaisuuksia tutkittiin muovin kovettamisen jälkeen. Vertailua tehtiin muun muassa nanomekaanisella pinnan analysoinnilla niistä muoveista, joiden esivalmistetta oli säilytetty jopa kaksi vuotta ennen näytteen valmistusta. Lisäksi tutkimuksessa kiinnitettiin erityistä huomiota kuitulujitteisen muovin liimautumiseen toiseen muoviin ja tällöin verrattiin erilaisten pinnan esikäsittelyaineiden vaikutusta rajapintaliitoksen sidoslujuuteen. Tulokset osoittivat tilastollisesti merkitseviä eroja näytteen pinnan nanokovuudessa pinnan eri kerrossyvyyksissä, mikä osoittaa semi-IPN gradienttirakenteen olemassaolon. Käytetyt kaksi esikäsittelyainetta saivat rajapintaliitoksen pinnan kovuuden lisääntymään näytteissä, jotka oli valmistettu tuoreesta kuitulujitteisen muovin esivalmisteesta. Myös esivalmisteen säilytysaika ennen sen käyttämistä vaikutti merkitsevästi liimautumiseen. Korkein sidoslujuus saavutettiin kuitulujitteisella muovilla, jonka pintaa ei oltu hiottu ennen liimaamista eli pinnan gradienttirakennetta ei oltu poistettu

Low-energy, planar magnetic defects in BaFe2As2: nanotwins, twins, antiphase and domain boundaries

In BaFe2As2, structural and magnetic planar defects begin to proliferate below the structural phase transition, affecting descriptions of magnetism and superconductivity. We study using density-functional theory the stability and magnetic properties of competing antiphase and domain boundaries, twins and isolated $nano$twins (twin nuclei) - spin excitations proposed and/or observed. These nanoscale defects have very low surface energy ($22$-$210$~$m$Jm$^{-2}$), with twins favorable to the mesoscale. Defects exhibit smaller moments confined near their boundaries -- making a uniform-moment picture inappropriate for long-range magnetic order in real samples. {\it{Nano}}twins explain features in measured pair distribution functions, so should be considered when analyzing scattering data. All these defects can be weakly mobile and/or have fluctuations that lower assessed "ordered" moments from longer spatial and/or time averaging, and should be considered directly.Comment: 6 pages, 6 figures, 1 tabl

Do Islamic stocks and commodity markets comove at different investment horizons ? evidence from wavelet time-frequency approach

The financial crisis during the last decade did not only affect the stock markets but also the commodity markets. The behavior and relation of these two markets have changed during and after the financial crisis. Therefore, an understanding of the relationship between commodities and stock markets is crucial, especially during the crisis, when investors are looking for alternative investment opportunities. In this paper, we focus on commodity markets and their relation with Islamic stock markets during the financial crisis. This is one of the first attempts to study this relationship in the important and growing area of Islamic capital markets. The paper applies the recent wavelet analysis to Dow Jones Islamic index and two commodity sector indices (Energy and Precious Metal) and it aims to reveal how they commoved in the period of the Global Financial crisis, which began in the USA as the Subprime mortgage crisis. Empirical results revealed that Islamic stock market commoved to a certain extent with the commodity indices during the whole period. Also, the wavelet correlation of stock markets and commodities differ significantly when talking about different investment horizons. We observed that stock markets are in general more correlated at different horizons with Energy sector than with Precious Metal. Further, based on wavelet coherence, it is observed that the co-movement between DJ Islamic and Energy Sector is significantly more compared to the co-movement with the Precious Metal commodity sector at different time scales and frequencies