Osakekurssin reagointi tulosvaroitukseen nousu- ja laskumarkkinoilla

Tutkimuksen tavoitteena on selvittää tapahtuuko tulosvaroituksen yhteydessä yli- tai alireagointia nousu- ja laskumarkkinoiden aikana. Tutkimus tehdään tapahtumatutkimuksena, jossa tarkoituksena on tutkia osakkeiden epänormaaleja tuottoja tulosvaroituspäivän ympärillä. Tapahtumaikkunan pituus on yhteensä 11 päivää [-5, +5]. Aineisto koostuu Helsingin pörssin OMXH25 indeksin yritysten julkaisemista tulosvaroituksista vuosien 1997–2009 välillä. Tälle aikavälille osuu 200 päivän liukuvalla keskiarvolla mitattuna kaksi nousu- ja kaksi laskumarkkinaa. Tutkimuksessa ei havaittu selvää yli- tai alireagointia nousu- tai laskumarkkinoilla. Sen sijaan tietty säännöllisyys reagoinnissa tulosvaroituksiin löydettiin: Nousumarkkinoilla, tulosvaroituspäivän jälkeen näkyy selvä positiivinen tuotto kahden päivän ajalta tulosvaroituksen jälkeen, riippumatta siitä onko kyseessä positiivinen vai negatiivinen tulosvaroitus. Vastaavasti laskumarkkinoilla löydettiin selvä negatiivinen epänormaali tuotto kahden päivän ajalta tulosvaroituksen jälkeen.

Optimal latent period in a bacteriophage population model structured by infection-age

We study the lysis timing of a bacteriophage population by means of a continuously infection-age-structured population dynamics model. The features of the model are the infection process of bacteria, the death process, and the lysis process which means the replication of bacteriophage viruses inside bacteria and the destruction of them. The time till lysis (or latent period) is assumed to have an arbitrary distribution. We have carried out an optimization procedure, and we have found that the latent period corresponding to maximal fitness (i.e. maximal growth rate of the bacteriophage population) is of fixed length. We also study the dependence of the optimal latent period on the amount of susceptible bacteria and the number of virions released by a single infection. Finally, the evolutionarily stable strategy of the latent period is also determined as a fixed period taking into account that super-infections are not considered

Alternative technique for biodiesel quality control using an optical fiber long-period grating sensor

We report the use of an optical fiber sensor to measure the soybean oil concentration in samples obtained from the mixture of pure biodiesel and commercial soybean oil. The operation of the device is based on the long-period grating sensitivity to the surrounding medium refractive index, which leads to measurable modifications in the grating transmission spectrum. The proposed analysis method results in errors in the oil concentration of 0.4% and 2.6% for pure biodiesel and commercial soybean oil, respectively. Techniques of total glycerol, dynamic viscosity, density, and hydrogen nuclear magnetic resonance spectroscopy were also employed to validate the proposed method.

Testing the Random Walk Hypothesis on the Baltic Stock Markets

The purpose of the thesis is to analyze whether the returns of general stock market indices of Estonia, Latvia and Lithuania follow the random walk hypothesis (RWH), and in addition, whether they are consistent with the weak-form efficiency criterion. Also the existence of the day-of-the-week anomaly is examined in the same regional markets. The data consists of daily closing quotes of the OMX Tallinn, Riga and Vilnius total return indices for the sample period from January 3, 2000 to August 28, 2009. Moreover, the full sample period is also divided into two sub-periods. The RWH is tested by applying three quantitative methods (i.e. the Augmented Dickey-Fuller unit root test, serial correlation test and non-parametric runs test). Ordinary Least Squares (OLS) regression with dummy variables is employed to detect the day-of-the-week anomalies. The random walk hypothesis (RWH) is rejected in the Estonian and Lithuanian stock markets. The Latvian stock market exhibits more efficient behaviour, although some evidence of inefficiency is also found, mostly during the first sub-period from 2000 to 2004. Day-of-the-week anomalies are detected on every stock market examined, though no longer during the later sub-period.