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Mezaka A.,University of Latvia | Susko U.,Latvian Society of Botanists | Opmanis A.,Latvian Academy of Sciences
Folia Cryptogamica Estonica | Year: 2011

Information on Schistostega pennata is limited in the Baltic countries. In Latvia S. pennata is listed as 'rare' in the Red data book but still little is known about the species distribution in relation to habitat and substrate. A search of all available literature and unpublished records provided information on about 21 S. pennata records in Latvia from 1924 until 2010 from different habitats and substrates. In total 18 records of S. pennata were found from protected areas. The latest records suggest that it is more common in Woodland Key Habitats on Picea abies root mass, than on sandstone in Latvia. Source


Kholkin A.L.,University of Aveiro | Kiselev D.A.,University of Aveiro | Bdikin I.K.,University of Aveiro | Sternberg A.,Latvian Academy of Sciences | And 4 more authors.
Materials | Year: 2010

Relaxors constitute a large class of ferroelectrics where disorder is introduced by doping with ions of different size and valence, in order to maximize their useful properties in a broad temperature range. Polarization disorder in relaxors is typically studied by dielectric and scattering techniques that do not allow direct mapping of relaxor parameters, such as correlation length or width of the relaxation time spectrum. In this paper, we introduce a novel method based on measurements of local vibrations by Piezoresponse Force Microscopy (PFM) that detects nanoscale polarization on the relaxor surface. Random polarization patterns are then analyzed via local Fast Fourier Transform (FFT) and the FFT PFM parameters, such as amplitude, correlation radius and width of the spectrum of spatial correlations, are mapped along with the conventional topography. The results are tested with transparent (Pb, La) (Zr, Ti)O3 ceramics where local disorder is due to doping with La3+. The conclusions are made about the distribution of the defectsresponsible for relaxor behavior and the role of the grain boundaries in the macroscopic response. © 2010 by the authors. Source


Spalvis K.,Latvian State Forestry Research Institute Silava | Daugaviete M.,Latvian State Forestry Research Institute Silava | Platace R.,Latvian Academy of Sciences | Daugavietis U.,Latvian State Forestry Research Institute Silava
International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM | Year: 2014

In the northern hemisphere Norway spruce (Picea abies Karst.) as one of the most productive and fast-growing conifer species has long been cultivated over vast areas. According to the literature data the spruce plantations in Europe take up some 6 to 7 million hectares. In the territory of present-day Latvia pure stands of spruce were established in woodlands already in the 19th century. Starting with the 1980s, spruce plantations for short rotation cultivation (till the age of 40 years) were on a larger scale established also in abandoned agricultural lands. Between 2000 and 2012, the area under similar plantations has reached 28,700ha. At first commercial thinnings at the age of 15 years the number of trees in the plantations is normally reduced to 1,500 stems•ha-1. In such a situation the major challenge is how to utilize the biomass thinned out. In the given study we have investigated the structure and amount of woody biomass that may be recovered in thinning 15-year pure stands of spruce. According to the field data, the weight of above-ground biomass of one tree in 15-year pure stands of spruce is on average 142.9kg (100%), of which stemwood makes 65.7 kg (46.0%) and tree foliage 76.9kg (53.9%), respectively. The biomass of green branches comprises the fraction of needles (38.1 kg or 49.5%) and young shoots (7.2kg or 9.4%), which in biomass studies is known as tree foliage. In 21 to 25-year pure stands of spruce the above-ground biomass of one tree weighs on average 372kg (100%), of which stemwood is 244.5 kg (65.7%) and tree foliage 117kg (31.5%), respectively In similar spruce plantations the number of trees removed in the first commercial thinnings is 1,210 trees ha-1 with the yield of pulpwood 27.1m3ha-1, or stem biomass 21.5t ha-1, and tree foliage 17.8t ha-1. When thinning 21to 25-year plantations, on average 877 trees ha-1 are thinned out, with the yield of pulpwood 109m3ha-1, or stem biomass 86.3t ha-1, and tree foliage 21.6t ha-1. The profit calculations, when utilizing also tree foliage, show that in thinning 15 to16-year spruce plantations the gross profit is 1.8 times higher, compared to the case when only pulpwood is utilized. For 21 to 25- year plantations this increase in gross profit is 1.2 times higher compared to utilizing pulpwood alone. © 2014, SGEM. All Rights Reserved. Source


Merkulovs D.,Riga Technical University | Dekhtyar Y.,Riga Technical University | Vilitis O.,University of Latvia | Shipkovs P.,Latvian Academy of Sciences | Merkulova V.,ELMI Ltd
IFMBE Proceedings | Year: 2015

Compact device of high sensitivity for measurement of the refractive indices for both stationary and flowing liquids has been developed. This device can be used to analyse a variety of biomedical liquids: urine, serum protein. The refractive index (RI) is determined by measuring the deviation of a laser beam passing through a cylindrical cuvette containing the test liquid. In order to significantly improve the resolution and stability of RI measurements, the repeated reflections and refractions of the light beam travelling through the cylindrical cuvette are employed. © Springer International Publishing Switzerland 2015. Source


Merkulovs D.,Riga Technical University | Dekhtyar Y.,Riga Technical University | Vilitis O.,University of Latvia | Shipkovs P.,Latvian Academy of Sciences | Merkulova V.,ELMI Ltd
IFMBE Proceedings | Year: 2015

Compact device of high sensitivity for measurement of the refractive indices of both stationary and flowing liquids has been developed. This device can be used to analyse a variety of biomedical liquids: urine, serum protein. The refractive index (RI) is determined by measuring the deviation of a laser beam passing through a cylindrical cell containing the test liquid. In order to significantly improve the resolution and stability of RI measurements, the repeated reflections and refractions of the light beam travelling through the cylindrical cell are employed. © Springer Science+Business Media Singapore 2015. Source

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