Numerical modelling of the backscattering of dual-polarization weather radar

Polarimetriset säätutkat ovat tulossa lähiaikoina operatiiviseen käyttöön Suomessa ja muualla maailmassa. Polarimetriset säätutkat tuovat lisää informaatiota ilmakehän hydrometeorien mittaukseen ja mahdollistavat siten perinteisiä säätutkia tarkemman sateen vesimäärän arvioinnin ja sateen olomuotojen luokittelun. Polarimetristen säätutkien parempaa hyödyntämistä varten tarvitaan lisää tietoa erilaisten hydrometeorien sirontaominaisuuksista . Tässä työssä tehtiin modifioitua DDA- eli diskreettidipoliapproksimaatiolaskentaa ja nollannen asteen säteilynkuljetusteoriaa käyttävä sirontamallinnusohjelma. Ohjelma kykenee laskemaan yksittäisen partikkelin eteenpäin ja takaisinsirontaparametrit eri polarisaatioille ja samoista kappaleista käyttäjän antamalla tiheydellä muodostuvan kerroksen sironta- ja vaimennusominaisuudet. Ohjelman toiminta validoitiin vertaamalla pallomaisten kappaleiden mallinnustuloksia analyyttisiin, ja siten tarkasti oikean tuloksen antaviin Mie-sirontatuloksiin. Ohjelmaa käytettiin sulavan lumi-, räntä- ja vesisateen etenemisvaimennuksen mallintamiseen. Ohjelmalla tutkittiin miten etenemisvaimennus muuttuu partikkelin sisältämän vesimäärän kasvaessa ja kuinka veden sijoittuminen eri puolille kappaletta vaikuttaa eri polarisaatioilla tapahtuvaan vaimennukseen. Sulamista mallinnettiin yksinkertaisella mallilla, jossa on neljä sulamisvaihetta. Vaimennusmallinnuksen tuloksista havaittiin, miten HH- ja VV-polarisaatioiden ero kasvaa voimakkaasti, kun partikkelin alaosaan kertyy nestemäistä vettä tai kun partikkelin muoto muuttuu litteämmäksi. Pallosymmetristä tilannetta kuvaavassa toisen sulamisvaiheen partikkelissa havaittiin oletuksen vastaisesti myös jonkin verran eroa polarisaatioiden vaimennustuloksissa. Ongelman oletettiin johtuvan tavasta, jolla partikkelit luotiin, eikä varsinaisesta mallinnusohjelmasta, joka vaikuttaa muuten toimivan oletetusti.Polarimetric weather radars will be in operational use in the near future. Polarimetric weather radars provide more information in the measurement of the atmospheric hydrometeors when compared to traditional weather radars. Hence more accurate estimates of the rain water content and precipitation types can be attained. In order to make better use of the features of polarimetric weather radars more information on the scattering properties of hydrometeors is needed. In this thesis a program, that models scattering using modified DDA calculation and the zeroeth degree radiative transfer theory, was made. The program is able to calculate forward and backscattering parameters of a single particle and scattering and attenuation properties for a layer consisting of those particles with a specified numerical density. The results from program for spherical particles were validated by comparing them to Mie scattering results, which are analytical, and therefore, true results for the scattering situation. The program was used to model attenuation due to hydrometeors in the melting layer. It was studied how the propagation attenuation changes when the water volume fraction in the particles increases and how differential accumulation of the water affects the attenuation in different polarization components. Melting of the particle was modeled with a simple model with four phases of melting. The results of the attenuation modeling suggest, that the difference between HH and VV polarizations increases strongly when more water accumulates in the bottom of the particle and when the particle changes to a flatter shape. The second phase of the melting was spherically symmetric but contrary, to the initial assumption, differences between attenuation results for different polarizations were noticed. The problem was assumed to be caused by the way the particles were generated and not by the program which otherwise seems to be working properly

Sähköisen kaupankäynnin hyödyntäminen paperitukkuliiketoiminnassa : case Papyrus Finland Oy

Siirretty Doriast

Abnormal behavior, striatal dopamine turnover and opioid peptide gene expression in histamine-deficient mice

Hypothalamic histaminergic neurons regulate a variety of homeostatic, metabolic and cognitive functions. Recent data have suggested a modulatory role of histamine and histamine receptors in shaping striatal activity and connected the histaminergic system to neuropsychiatric disorders. We characterized exploratory behavior and striatal neurotransmission in mice lacking the histamine producing enzyme histidine decarboxylase (Hdc). The mutant mice showed a distinct behavioral pattern during exploration of novel environment, specifically, increased frequency of rearing seated against the wall, jumping and head/body shakes. This behavioral phenotype was associated with decreased levels of striatal dopamine and serotonin and increased level of dopamine metabolite DOPAC. Gene expression levels of dynorphin and enkephalin, opioids released by medium spiny neurons of striatal direct and indirect pathways respectively, were lower in Hdc mutant mice than in control animals. A low dose of amphetamine led to similar behavioral and biochemical outcomes in both genotypes. Increased striatal dopamine turnover was observed in Hdc KO mice after treatment with dopamine precursor l-Dopa. Overall, our study suggests a role for striatal dopamine and opioid peptides in formation of distinct behavioral phenotype of Hdc KO mice.Peer reviewe

Repeated Ethanol Exposure Alters DNA Methylation Status and Dynorphin/Kappa-Opioid Receptor Expression in Nucleus Accumbens of Alcohol-Preferring AA Rats

Growing evidence suggests that epigenetic mechanisms, such as DNA methylation and demethylation, and histone modifications, are involved in the development of alcohol and drug addiction. However, studies of alcohol use disorder (AUD) that are focused on epigenetic DNA modifications and gene expression changes remain conflicting. Our aim was to study the effect of repeated ethanol consumption on epigenetic regulatory enzymes such as DNA methyltransferase and demethylase enzymes and whether those changes affected dynorphin/kappa-opioid receptor system in the Nucleus Accumbens (NAc). Two groups of male alcohol-preferring Alko Alcohol (AA) rats, rats which are selectively bred for high voluntary alcohol consumption and one group of male Wistar rats were used. The first group of AA rats had access to alcohol (10% ethanol solution) for 90 min on Mondays, Wednesdays and Fridays over a period of 3 weeks to establish a stable baseline of ethanol intake (AA-ethanol). The second group of AA rats (AA-water) and the Wistar rats (Wistar-water) were provided with water. Using qPCR, we found that voluntary alcohol drinking increased Dnmt1, -3a, and -3b mRNA levels and did not affect Tet family transcripts in the AA-ethanol group when compared with AA- and Wistar-water rats. DNMT and TET enzymatic activity measurements showed similar results to qPCR, where DNMT activity was increased in AA-ethanol group compared with AA-water and Wistar-water groups, with no statistically significant difference between groups in TET enzyme activity. In line with previous data, we found an increased percentage of global DNA methylation and hydroxymethylation in the AA-ethanol group compared with control rats. Finally, we investigated changes of selected candidate genes from dynorphin/kappa-opioid receptor system (Pdyn, Kor) and Dnmt3a genes that might be important in AUD-related behaviour. Our gene expression and promoter methylation analysis revealed a significant increase in the mRNA levels of Pdyn, Kor, and Dnmt3a in the AA-ethanol group, however, these changes can only be partially associate with the aberrant DNA methylation in promoter areas of the selected candidate genes. Thus, our findings suggest that the aberrant DNA methylation is rather one of the several mechanisms involved in gene expression regulation in AA rat model.Peer reviewe