While a host of economic variables have been identified in the literature with the apparent in-sample ability to predict the equity premium, Goyal and Welch (2007) find that these variables fail to deliver consistent out-of-sample forecast gains relative to the historical average. Imposing theoretically motivated restrictions on individual predictive regression models, Campbell and Thompson (20...

Sample preparation is an essential step in analysis, greatly influencing the reliability and accuracy of resulted the time and cost of analysis. Solid-Phase Microextraction (SPME) is a very simple and efficient, solventless sample preparation method, invented by Pawliszyn in 1989. SPME has been widely used in different fields of analytical chemistry since its first applications to environmental...

in this article, we characterize the involutiveness of the linear combination of the forma1a1 +a2a2 when a1, a2 are nonzero complex numbers, a1 is a quadratic or tripotent matrix,and a2 is arbitrary, under certain properties imposed on a1 and a2.

in recent years, sub-band speech recognition has been found useful in addressing the need for robustness in speech recognition, especially for the speech contaminated by band-limited noise. in sub-band speech recognition, the full band speech is divided into several frequency sub-bands, with the result of the recognition task given by the combination of the sub-band feature vectors or their lik...

in the course of this study, the number of recorded chalcidids (hym.: chalcididae) from iranincreased to 42 species (including one unidentified species of the genus lasiochalcidia masi), of whichfifteen species and four genera are new to iranian chalcidid fauna. the family chalcididae is repredentedby three subfamilies in iran as follows: chalcidinae (16 species), dirhininae (two species), andh...

introduction: pulsed dye laser (pdl) has been used to treat acne lesions and scar erythema by interrupting superficial vasculature. salicylic acid chemical peels are employed chiefly due to their lipophilic, comedolytic, and anti-inflammatory properties. although studies have looked at peels and laser therapy independently in acne management, we examined these treatments in combination. our pri...

background and objective: in this study due to increasing importance of producing low fat meat products such as low calorie hamburger and in order to developing new and safe product with low fat and saturated fatty acid content and high unsaturated fatty acid, the effect of reducing animal fat content and adding combination of healthier oil, olive oil and canola oil that were used as a substitu...

Optically pumped helium magnetometers are important instruments whichhave many applications in military, mass spectroscopy and space applications. In thispaper, the working principles of helium magnetometers have been explained. There isalso an introduction of a new method for finding the resonant frequency, which hasadvantages to the typical method such as more sample r...

A new approach is described for the combination of electron ionization and LC–MS based on sample ionization as vibrationally cold molecules in a supersonic molecular beam (Cold EI). Cold EI of sample compounds in liquid solutions (methanol, acetonitrile, water, etc.) is achieved through spray formation, followed by soft thermal vaporization of the sample particles prior to their supersonic expa...