Long-term pathological consequences of resin tapping wounds on stems of Scots pine (Pinus sylvestris L.)

Key message After 5-6 decades since inflicting resin tapping wounds, overmature (> 120 years old) Pinus sylvestris stems remain undecayed and vigorous. Overmature trees of Pinus sylvestris bearing large wounds made by resin tapping decades ago are still present in woodlands of south-eastern Baltic Sea region. The aim of the present study was to investigate health condition of those trees focusing on fungal infections and to estimate impact of the injury on radial stem growth. The study was conducted in Latvia in three overmature stands of P. sylvestris, resin-tapped in 1950-1970 s. On the studied ninety 120-167-year-old trees, exposed sapwood constituted from 1140 to 7755 cm(2) per individual stem. Of the 127 wounds sampled, 52 (41%) showed wood discoloration. The discoloration in its extent was limited, expanding beyond wound margins approx. 1 (max 3) cm in radial, and 6-7 cm in longitudinal directions. Of the 127 wood samples/wounds subjected to fungal isolations, 96% resulted in fungal growth, yielding 236 fungal isolates that represented 47 fungal taxa. The most common among macro-fungi was basidiomycete Porodaedalea pini, which was isolated from 9% of stems. The fungus is currently classed not as a tree pathogen, but instead as an indicator species for woodland sites to be considered for nature conservation. Data from tree ring widths have revealed that tree reacted to the resin tapping injury by increasing radial increment of the un-affected part of the circumference of the stem. Current study demonstrated that even on the long term, resin tapping has little influence on health condition and vitality of P. sylvestris, even at the very old age. This should be considered as a supporting message in case resin taping practices in the region are to be revived

Sea Buckthorn (Hippophae rhamnoides) Waste Biomass after Harvesting as a Source of Valuable Biologically Active Compounds with Nutraceutical and Antibacterial Potential

Funding Information: Funding: This research was funded by ERDF project nr. Nr.1.1.1.1/19/A/146 “Biorefinery processing of sea buckthorn non-fruit biomass using innovative techniques and comprehensive analytical investigation, for obtaining prospective for Latvian bioeconomy high value-added products, including serotonin”. Publisher Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland.For sustainable sea buckthorn (Hippophae rhamnoides) berry production, the task at hand is to find an application for the large amount of biomass waste arising at harvesting. Sea buckthorn (SBT) vegetation is currently poorly studied. The purpose of this research was to assess the composition and potential of SBT twigs as a source of valuable biologically active substances. Water and 50% EtOH extracts of twigs of three Latvian SBT cultivars with a high berry yield and quality, popular for cultivation in many countries (H. rhamnoides ‘Maria Bruvele', ‘Tatiana', ‘Botanicheskaya Lubitelskaya'), were investigated for the first time. The phytochemical composition (UHPLC-ESI-MS/MS analysis) and biological activity of the obtained hydrophilic extracts were determined. The highest yield of polyphenolic compounds and serotonin was observed for ‘Maria Bruvele'. Hydrophilic extracts were investigated for radical scavenging activity (DPPH' test), antibacterial/antifungal activity against five pathogenic bacteria/yeast, cytotoxicity, and the enzymatic activity of alpha-amylase (via in vitro testing), which is extremely important for the treatment of people with underweight, wasting, and malabsorption. The results showed a high potential of sea buckthorn biomass as a source of valuable biologically active compounds for the creation of preparations for the food industry, nutraceuticals, and cosmetics.publishersversionPeer reviewe

I Sense, Therefore I act? An Active Inference Perspective on Relationship Between Attention and Motor Preparation Time

Pētījuma mērķis ir labāk izprast psiholoģisko procesu pamatprincipus, par teorētisko bāzi izmantojot aktīvo inferenci. Aktīvā inference postulē, ka cilvēka psihe ir saprotama kā hierarhisks maņu prognožu cikls – nevis kā maņu signālu saņēmēja un apstrādātāja, bet kā to aktīva radītāja, kurā uztvere un darbības ir analoģiski, uz maņu prognozēm balstīti procesi, un kustību veikšanu var saprast kā maņu prognožu piepildīšanu. Izmantojot uztveres analoģiju, pētījumā tiek eksperimentāli pārbaudīts, vai kustību sagatavošanu var saprast kā uzmanību, kas veltīta ķermeņa iekšējo maņu prognozēm.This research tries to better understand the most basic principles of psychological processes using active interference as theoretical basis. Active inference postulates that human psyche can be understood as a hierarchical cycle of sensory predictions – not as a receiver and processor of sensory signals, but their active creator that uses perception and action – two analogous processes based on sensory predictions, and thus movement can be understood as fulfillment of sensory predictions. Using perception as the analogy the study experimentally examines whether motor preparation can be understood as attention paid to the predictions of the body's internal senses

Romas viesnīca: [oriģinālfotogrāfiju albums]

Fotogrāfa vārds reljefā iespiedumā fotogrāfiju apakšējā labajā stūrī, bez datējuma

Heat Transfer Characteristics of Crushed Rock and Lightweight Aggregate Materials

Over the last decades there has been a major transition to using crushed rock materials for road and railway construction instead of natural materials such as sand or gravel. In addition, it is common practice to use very coarse and sometimes open graded materials for structural layers. Knowledge of the thermal properties of construction materials is crucial for proper thermal design for road and railway structures. Thermal conductivity is the governing heat transfer mechanism in most such materials. However, with coarse open graded materials, natural air convection can make a significant contribution to the overall heat transfer. This study investigates the heat-transfer characteristics of granular materials with a focus on natural air convection. It consists of three parts: i) small-scale experiments on particle thermal conductivity and crushed rock thermal conductivity, and the validation and adaptation of an existing thermal conductivity model; ii) large-scale experiments on natural convection, the establishment of intrinsic permeability and subsequent modeling of large scale experiments; iii) investigations of possible air convection under field conditions in a full-scale road structure. The small-scale experiments showed to have good results on thermal conductivity measurements of particle thermal conductivity and thermal conductivity of crushed rock materials. For the validation and adaptation of the thermal conductivity model, 42 samples were prepared and 328 tests conducted in unfrozen and frozen states with different degrees of moisture content. A large-scale heat transfer cell with an inner volume of 1m3 was used to measure the increase in heat transfer due to natural air convection. A method based on the analytical Nusselt (Nu)-Rayleigh (Ra) number relationship was used to establish the intrinsic permeability (K) of different construction materials. These included three crushed rock materials (20/120, 40/120 and 20/250 mm) and two lightweight aggregates: expanded clay and foam glass. The experimental results showed that natural air convection could be initiated in all three crushed rock materials at a fairly low temperature gradient (∇T) of 4.5 to 6.5° C/m. The established K for crushed rock materials ranged from 1.1 to 2.2x10-6 m2. Air convection for foam glass and expanded clay (10/20 mm) material was initiated at critical ∇T of 11.0 and 22.5°C/m respectively. The corresponding K values based on the experimental measurements were 0.86 and 0.17x10-6 m2. The overall results show that air convection can be induced at a relatively low ∇T. To observe material characteristics under field conditions, a full-scale test site was constructed incorporating ten different sections. This study, however, focuses on only two sections, which had layers of open graded materials. Observations of the temperature profiles during the cooling period found that ∇T exceeded the critical value in all open graded layers. However, given that the air convection also depends on layer thickness, apparent Rayleigh number (Ra*) was calculated. The results show that Ra* exceeded the critical value only in a 1.0 m thick frost protection layer (40/120 mm crushed rock) and a 0.6 m thick foam glass layer (10/60 mm). To further investigate possible air convection under field conditions, a numerical model was developed. The results from the model clearly show the presence and effect of air convection. However, it could be that the effect of convection was overestimated, given that the K values were established under laboratory conditions with materials with no compaction. To sum up, this study has shown that a simple thermal conductivity model could be adapted, with slight calibration, for the estimation of thermal conductivity in crushed rock materials. The study has also shown that natural air convection could easily be initiated in coarse materials used in road construction under relatively low temperature gradients. The study at the field test site found that layers with coarse, open graded materials are exposed to very high temperature gradients. The field observations and analysis together with the numerical model showed the possible presence of natural air convection. Air convection can have an adverse effect on seasonal freezing environments by increasing the depth of frost penetration, resulting in possible differential heaving

Hypothesis testing using nonparametric tests

Lai pārbaudītu statistiskas hipotēzes, ir izstrādāti daudzi statistiskie testi. Piemēram, hipotēžu pārbaudei par izlašu vidējo vērtību vienādību izplatītākie ir t-tests un vienfaktora dispersiju analīze (ANOVA), taču, tā kā tie ir parametriski testi, tad ir jāizpildās konkrētiem pieņēmumiem, lai šos testus varētu pielietot, turklāt diskrētā veidā uzdotiem datiem šie testi nemaz neder. Šajā darbā aplūkoti vairāki neparametriski testi, kas ir labas alternatīvas parametriskajiem testiem, kā arī paskaidrota atšķirība starp parametriskajiem un neparametriskajiem testiem. Katrā nodaļā aplūkotas atšķirīgas situācijas pēc izlašu skaita un to savstarpējās atkarības, savukārt apakšnodaļās aplūkoti piemērotākie testi atbilstošajam datu formātam. Darba noslēgumā iekļauti piemēri dažiem no aplūkotajiem testiem.There have been developed several statistical tests for testing statistical hypothesis. For example, for testing hypothesis about the equality of sample means, the most common tests are t-test and one-way analysis of variance (ANOVA), but, as they are parametric tests, there are certain assumptions about the data that have to be met before the test can be properly used, plus for discrete data, the parametric tests are invalid. In this paper several nonparametric tests are discussed, and the difference between [arametric and nonparametric tests is reviewed. Each chapter is devoted for different situation based in the number of samples and their dependence, whereas each sub-chapter describes the most appropriate test for the type of data. At the end a few examples are included for some of the tests

Economic assesment of forest tree-breding

Meža nozare ir viena no svarīgākajām Latvijas tautsaimniecības nozarēm. Koksne un tās izstrādājumi ir viena no vadošajām eksporta precēm, turklāt meža nozarē ir nodarbināti ap 45 tūkstošiem iedzīvotāju. Ar meža selekcijas palīdzību ir iespējams nodrošināt pieejamo koksnes resursu palielinājumu ilgtermiņā, taču tās veikšana prasa ieguldījumus gan laika, gan naudas izteiksmē. Lai novērtētu šo ieguldījumu ekonomisko pamatotību, veikta selekcijas procesa izmaksu un ieguvumu analīze. Tās ietvaros pētīta dažādu parametru ietekme uz kopējo rezultātu, pieļaujot atšķirīgus nākotnes scenārijus. Rezultātā gūts apstiprinājums meža selekcijas potenciālam mežaudžu finansiālās vērtības paaugstināšanā, nosedzot paša selekcijas procesa izdevumus, un sniegti ierosinājumi selekcijas tālākai attīstībai.Forest sector is one of the most important industries in Latvia. Wood and its products are one of the leading export goods, furthermore approximately 45 thousand inhabitants are employed in forest sector. Tree-breeding is a possibility to increase the amount of accessible wood resources in long-term, however the realization of tree-breeding needs investments both in the expression of time and money. The cost-benefit analysis of tree-breeding is done to evaluate the economic validity of such investments. The influence of several parameters on total outcome is investigated to provide results for different future scenarios. As a result affirmation of the potential of tree-breeding in increasing the financial value of forests while covering its costs is obtained, as well as suggestions for the further development of tree-breeding are given

Experimental study on the effect of soil moisture content on critical temperature rise for typical cable backfill materials

The increased utilization of power grid requires operating power cables close to their thermal limit. Buried power cables in such condition experience thermal instability where thermal resistance increases as the moisture migrates away from the proximity of the cable forming a dry-out zone. While it is common to use a two-zone model to account for the dry-out zone in ampacity calculations, there is a limited number of studies on characterizing backfill materials for their critical temperature rise ( Δθx ), especially for crushed rock sands. In addition, dependency of the Δθx on moisture content is sometimes not acknowledged. This study measures the Δθx for three typical backfill materials and investigates the relationship between Δθx and moisture content. The results show that crushed rock sand has higher Δθx compared to natural sand. Overall, large range of Δθx was measured depending on moisture content and type of soil. Ampacity calculations with the established Δθx show that at low moisture content, the thermal resistivity of the soil has a higher influence on ampacity than Δθx . At relatively high moisture content, the Δθx becomes the predominant factor governing the overall ampacity