9480 research outputs found
Sort by
An Analysis of Forest Management with Selection Cuttings: A Case Study of RMK Logging Areas
No full textMagistritöö
Metsamajanduse ja metsaökoloogia õppekavalErinevate metsamajandamise viiside kasutamise eelised ja puudused on metsanduses olnud pikka aega arutluse all. Viimastel aastatel on Eestis lageraiete kõrval hakatud üha enam tähelepanu pöörama ka püsimetsana majandamisele valikraiete abil. Valikraie võimaldab säilitada pidevat metsakatet ja elurikkust, kuid selle majanduslik tasuvus on olnud võrreldes traditsioonilise lageraiega ebaselge ning Eestis on nappinud praktilisi uuringuid. Käesoleva magistritöö eesmärk on analüüsida, kas ja millistel tingimustel on valikraiel põhinev metsa majandamine majanduslikult elujõuline alternatiiv lageraiele. Uurimuses kasutati aastatel 2019–2024 RMK-s tehtud 13 valikraie majandusnäitajaid ning aastatel 1994–2014 valikraietega majandatud puistute inventeerimisandmeid. Erinevate raieviiside ökonoomilise tasuvuse hindamiseks arvutati puidu müügist saadav puhastulu nii hektari kui ka tihumeetri kohta. Lisaks analüüsiti puistute majandamise tulevasi rahavooge, arvutades nende puhasnüüdisväärtuse erinevate diskontomäärade alusel. Varasemate valikraiete järel tekkinud puistu teise rinde kujunemist analüüsiti logistilise regressiooni abil. Uuriti valikraiele järgnenud töid ja metsakategooria muutusi. Tulemused näitavad, et lageraied annavad keskmiselt 30% kõrgemat puhastulu iga raiutud puiduühiku kohta. Samas võib valikraie üksikjuhtudel pakkuda pindalaühiku kohta võrreldavat tulu ning tagada pikaajalise stabiilse tuluvoo. Madala intressimäära (1–2%) korral osutus valikraietega majandamise rahavoogude puhasnüüdisväärtus võrreldavaks või isegi suuremaks kui lageraie puhul. Kõrgema intressimäära (3% ja 5%) korral andsid seevastu parema majandusliku tulemuse lageraied. Selgus, et valikraiete edukus sõltub korduvate raiete tulu stabiilsusest ja loodusliku uuenemise õnnestumisest. Vanemate valikraielankide analüüs näitas, et uue metsapõlvkonna teke ei ole alati tagatud ning sõltub paljudest eri teguritest nagu näiteks puuliik, metsakasvukohatüüp, puistu struktuur jne. Töö tulemused kinnitavad varasemates uuringutes esile toodud püsimetsanduse pikaajalisi ökoloogilisi eeliseid, samas kui majanduslikus võrdluses osutub valikraie selgelt vähem tulusaks kui lageraie. Võib järeldada, et valikraie on riigimetsas toimiv ja jätkusuutlik majandamisviis peamiselt hoiu- ja kaitsemetsades, kuigi teatud tingimustel ka majandusmetsades. Küll aga aitab valikraie tasakaalustada metsamajanduse majanduslikke huve loodusväärtuste säilitamise ning ökosüsteemiteenuste ja elurikkuse kaitsega. Soovitan edaspidi jätkata varasemate valikraiete pikaajalist seiret ning viia läbi täiendavaid uuringuid valikraie praktikate täiustamiseks.The advantages and disadvantages of different forest management practices have been a subject of long-standing debate in forestry. In recent years, alongside clear-cutting, increasing attention in Estonia has been given to continuous-cover forestry applying selection cuttings. While selection cutting enables the maintenance of continuous canopy and biodiversity, its economic profitability compared to clear-cutting remains unclear, and practical studies in Estonia are limited. This master’s thesis assesses whether, and under what conditions, forest management based on selection cutting can be a financially viable alternative to clear-cutting. The study uses economic indicators from 13 selection cuttings conducted by RMK (2019–2024) and inventory data from stands managed with selection cutting (1994–2014). Net revenue from timber sales was calculated per hectare and per cubic metre, and the net present value (NPV) of future cash flows was analyzed under various discount rates. Second-layer formation following earlier selection cuttings was examined using logistic regression. Results show that, on average, clear-cutting yields 30% higher net revenue per unit of timber. However, in some cases, selection cutting can provide comparable revenue per hectare and ensure a more stable long-term income. At low discount rates (1–2%), the NPV of selection cutting was comparable to or exceeded that of clear-cutting; at higher rates (3–5%), clear-cutting yielded better outcomes. The success of selection cutting depends on stable revenues from repeated harvests and effective natural regeneration. Older selection cutting sites showed that regeneration is not always guaranteed and depends on factors such as species, site type, and stand structure. These findings align with earlier studies highlighting the long-term ecological benefits of continuous-cover forestry, while confirming that selection cutting remains significantly less profitable economically. It can be concluded that selection cutting is a viable and sustainable option primarily in conservation and protection forests, and in certain cases, also in commercial forests. Furthermore, it offers a way to reconcile economic goals in forestry with the conservation of biodiversity and ecosystem services. Continued monitoring of past selection cuttings and further research into improving these practices are recommended
Ecohydraulic modeling on an artificial rapid in the Laeva river
No full textMagistritöö
Vesiehituse ja veekaitse õppekavalKäesolev magistritöö käsitleb kalade rändetingimuste hindamist tehiskärestiku tüüpi kalapääsus muutuvate hüdroloogiliste olude juures. Probleemi aktuaalsust suurendab kliimamuutustest tingitud voolurežiimi muutus Eesti jõgedes, mis mõjutab rände tingimusi kevadisel perioodil, mil toimub paljude kalade kudemisperiood.
Voolurežiimi muutuste analüüsimisel kasutati sisendina 1960–2020. aasta ööpäevaseid äravoolumooduleid kümnel Ida-Eesti vesikonna jõel. Lisaks analüüsiti eraldi uuritava Laeva jõe arvutuslike vooluhulkasid aastatel 1960–2024. Töös esimeses osas analüüsiti trende 30 päeva keskmistes minimaalsetes äravooludes ja leiti, et talvisel perioodil on minimaalsed vooluhulgad oluliselt kasvanud, samas kui mai kuu minimaalsed vooluhulgad on vähenenud.
Laeva jõe tehiskärestiku toimivust hinnati ökohüdraulilise modelleerimisega, kus särg (Rutilus rutilus) oli uuritavaks kalaliigiks. Hüdraulilise modelleerimise sisendina kasutati ööpäevaseid arvutuslike vooluhulkasid aastal 2019, mida võib pidada vaeevaseks aastaks. Metoodikas kombibeeriti HEC-RAS tarkvaras koostatud 2D hüdrauliline mudel elupaiga sobivusindeksiga (HSI). HIS koondindeks põhines iga võrgusilma voolukiiruse ja veesügavuse osaindeksist.
Tulemused näitasid, et rajatud Laeva tehiskärestik tagab särjele sobivad rändetingimused. Kärestiku ülesvoolu osas võimaldavad madalveesäng ja seda ümbritsev madalam ala kalade läbipääsu erinevate vooluhulkade korral. Kärestiku allavoolu osas, kus madalveesäng puudub, jääb väga väikeste vooluhulkade puhul veekiht kalade liikumiseks liiga madalaks.
Antud tööd kinnitab, et ökohüdrauliline modelleerimine on kauslik tööriist, mis sobib kalapääsude hindamiseks nii hüdraulilisest kui bioloogilisest aspektist juba projekteerimise etapis. Meetodi laiem rakendamine Eestis suurendaks kalapääsude tõhusust ning parendaks veekeskkonna taastamiseks kasutatavate vahendite kasutamise efektiivsust.This master's thesis analyses fish migration conditions in an artificial rapid under changing hydrological conditions. The relevance of the topic is increased by climate change-induced alterations in the flow regime of Estonian rivers, particularly affecting the spring period that coincides with the spawning season of many fish species.
To analyse changes in the flow regime, daily specific discharge data from 1960 to 2020 were used from ten rivers in the eastern Estonian basin. Additionally, theoretically calculated discharge rates for the Laeva River from 1960 to 2024 were analysed separately. The first part of the study investigated trends in the 30-day moving average of minimum discharge values and found that minimum discharge has significantly increased in winter, while the values in the month of May show a decreasing trend.
The Laeva River artificial rapid fish passage effectiveness was assessed using ecohydraulic modelling, with the roach (Rutilus rutilus) as a model species. Hydraulic modelling was based on daily discharge data from the low-flow year 2019. The methodology combined a 2D hydraulic model built with HEC-RAS software with a habitat suitability index (HSI) analysis to assess the fish passage effectiveness. HSI composite index was based on sub-indices from flow velocity and water depth from each grid point.
The results showed that the constructed Laeva rapid provides suitable conditions for roach migration. The upstream section with a low-flow channel and the surrounding shallower area ensure fish passage under various flow conditions. In contrast to the downstream section, where the low-flow channel is not constructed, the fish passage effectiveness is low under low flow conditions due to low water depth.
The study confirms that ecohydraulic modelling is a useful tool for evaluating fish passage effectiveness already at the design stage. Wider adoption of this method in Estonia would enhance the effectiveness of fish passages and also improve the efficiency of resource management in aquatic habitat restoration
Accessibility of Everyday Services for Residents of Tartu Based on the 15-Minute City Concept
No full textMagistritöö
Geodeesia, kinnisvara- ja maakorralduse õppekaval15-minutilise linna kontseptsioon lähtub ideest, et kõik igapäevaseks eluks vajalikud teenused peaksid olema kättesaadavad kuni 15-minutilise jalgsikäigu kaugusel. Selline ruumiline korraldus toetab jätkusuutlikku linnakeskkonda, suurendab elukvaliteeti ja vähendab sõltuvust autotranspordist.
Magistritöö eesmärk on hinnata igapäevateenuste kättesaadavust Tartu linna elanikele, tuginedes 15-minutilise linna kontseptsioonile. Analüüs hõlmas üheksat teenuseliiki: kooliteenus, lasteaiateenus, toidukauplused, apteegid, esmatasandi tervishoiuteenused, pangaautomaadid, pakiautomaadid, ühistranspordipeatused ja vabaajataristu. Teenuste kättesaadavuse hindamiseks kasutati võrgupõhist ruumianalüüsi, mis modelleerib jalakäija liikumist mööda tegelikku teedevõrku.
Tulemuste põhjal selgus, et suurem osa Tartu linna elanikest elab käsitletavatest teenustest 15-minutilise jalgsikäigu kaugusel. Kõige paremini on kättesaadavad toidukauplused, lasteaiad ja lastehoiud, apteegid, panga- ja pakiautomaadid, ühistranspordipeatused ning vabaajataristu. Kitsaskohad ilmnesid kooliteenuse ja esmatasandi tervishoiu kättesaadavuses, eriti äärelinna elamupiirkondades. Töö tulemused pakuvad sisendit ruumilise planeerimise ja linnakeskkonna arendamise protsessidesse, tuues esile piirkonnad, kus teenuste kättesaadavust tuleks tulevikus parandada.The concept of the 15-minute city is based on the idea that all essential daily services should be accessible within a 15-minute walk from one's home. This spatial model supports sustainable urban development, enhances quality of life, and reduces dependence on private car use.
The aim of this thesis was to evaluate the accessibility of everyday services for residents of the city of Tartu, based on the principles of the 15-minute city. The analysis focused on nine categories of services: primary schools, kindergartens, grocery stores, pharmacies, primary healthcare providers, ATMs, parcel lockers, public transport stops, and recreational infrastructure. Accessibility was assessed using network-based spatial analysis that models pedestrian movement along the actual street network.
The results indicate that the majority of Tartu’s residents live within a 15-minute walking distance from the analysed services. The best-covered services were grocery stores, kindergartens and childcare facilities, pharmacies, ATMs, parcel lockers, public transport stops, and recreational areas. The greatest shortcomings were found in access to schools and primary healthcare, particularly in suburban residential areas. The findings offer practical insights for spatial planning and urban development, highlighting areas where access to essential services needs to be improved in the future
Sub-clinical respiratory infection identified on farms by monitoring weight changes of pigs with the Weight-Detect instrument
No full textReceived: January 13th, 2025 ; Accepted: April 17th, 2025 ; Published: April 29th, 2025 ; Correspondence: [email protected] essential task of growth rate monitoring of pigs is usually undertaken on farms using electronic scales, but new technologies are now available to continuously monitor the weight of pigs. One of these systems (Weight-Detect, WD, PLF Agritech, Brisbane, Australia) has been introduced on a commercial pig farm in Spain as part of the EU funded aWISH project to (1) assess the applicability of the technology and (2) use this information to assess the general welfare status of pigs. The WD unit was installed in early 2024 and manual weight recordings were undertaken periodically using an electronic scale to validate the WD system. In terms of absolute values, the manual measurements indicated that the WD system was able to predict the average pen weight of the pigs with 1.7% (2.0 kg) precision. More importantly, this case study demonstrated that the WD unit was able to detect weight reduction in pigs six days before the clinical signs of a respiratory disease infection were noticed. According to the WD measurements the study pigs achieved an average daily gain (ADG) of 882 g d-1 between the 20/03/24 and 16/04/2024. However, between the 17/4/2024 and 30/04/2024 their ADG dropped dramatically to 286 g d-1. The animals were diagnosed with respiratory disease on the 22/04/24, six days after the dramatic reduction in ADG was recorded by the WD system. This period of ADG stagnation has caused an approximate 14-day delay in reaching the desired slaughter weight, (approx. 130 kg), potentially creating significant financial losses for the producer. After the 1/05/24 pigs recovered and achieved an ADG of 645 g d-1 until their last recorded weighing day on the 20/5/24. These results highlight the WD system’s ability to alert livestock managers about impending health problems before clinical signs appear, so appropriate mitigation measures can be implemented to reduce the negative impacts on welfare and production performance
Biosecurity in Estonian dairy and beef cattle herds, results of Biocheck.UGent assessment : [presentation]
No full textHorizon Europe BIOSECURE project.
Effective biosecurity is essential for preventing disease and ensuring farm sustainability. The objective was to assess the current biosecurity status of the Estonian cattle farms to raise awareness and support future improvements.Funded by the European Unio
Development of a fermented oat-based beverage using kefir starter culture
No full textBakalaureusetöö
Toiduainete tehnoloogia õppekavalTaimsed piimatoodete alternatiivid koguvad järjest rohkem populaarsust, sest need sobivad suuremale tarbijaskonnale. Fermentatsiooni järgselt võivad need joogid omandada probiootilise toime, mis tugevdab seedesüsteemi mikrofloorat. Tootmisprotsessis keeruline saavutada taimsest toorainest toodet, mis sarnaneks sensoorsete omaduste poolest keefirile. Üheks põhjuseks on taimses joogis leiduvate valkude ja rasvade väiksem sisaldus, mis mõjutab tekstuuri, maitse tasakaalu ja fermenteerimisvõimet.
Bakalaureusetöö eesmärk oli uurida keefiriseene ja starterkultuuriga fermenteeritud kaerajoogi omadusi. Töö raames fermenteeriti kuus proovi, mille suhkrusisaldus oli 2%, 3% ja 4%. Lisati vastavalt starterkultuur või keefiriseen. Fermentatsioon toimus 18 tundi temperatuuril 37 °C. Enne fermenteerimist määrati kaerajoogi tiitritav happesus, pH ja lahustunud kuivaine sisaldus (Brix). Pärast katsete lõppu määrati samuti tiitritav happesus, pH, Brix ning lisaks viidi läbi sensoorne analüüs, kus hinnati välimust, lõhna, maitset, konsistentsi, magusust ja happesust.
Töö tulemustest selgus, et kõikide proovide pH langes algtasemelt 7,49±0,046 vahemikku 4,59–4,95. Madalaima pH oli proov KJ 2% (4,59±0,49), millel oli ka kõrgeim tiitritav happesus (43,87±2,57 °Th). Statistiliselt oluline erinevus tiitritavas happesuses ilmnes proovide KJ 3% ja KS 3% vahel (p = 0,0014). Brix langus viitas sellele, et fermentatsiooni käigus tarbisid mikroorganismid aktiivselt suhkrut. Sensoorse analüüsi tulemuste põhjal selgus, et starterkultuur ja suhkru kontsentratsioon mõjutas enim magususe ja happesuse tajumist. Parima lõhnahinnangu sai proov KJ 3%. Välimuse ja konsistentsi hinnangud ei erinenud märgatavalt. Keefiriseenega katse teise korduse proovid jäeti sensoorsest hindamisest välja, kuna jook oli visuaalselt ja lõhna poolest riknenud – jook eraldus tugevalt, muutus tükiliseks ja lõhnas alkohoolselt.
Käesoleva bakalaureusetöö tulemused näitavad, et stabiilsema tulemuse annab fermentatsioonil starterkultuuride kasutamine. Lisaks mõjutab starterkultuuri ja suhkru kontsentratsiooni kooslus keemilisi ja sensoorseid omadusi. Kokkuvõttes saab kaerajoogist valmistada taimset keefiri alternatiivi, mille organoleptilised omadused vajavad veel optimeerimist.Plant-based dairy alternatives are gaining popularity, as they are suitable for a wider range of consumers. After fermentation, these drinks may acquire probiotic properties that support the gut microbiota. However, achieving a product from plant-based raw materials that resembles kefir in its sensory characteristics is challenging in the production process. One of the reasons is that plant-based drinks compared to milk have a lower level of proteins and fats that affect fermentation capacity, texture and flavour balance.
The aim of this bachelor’s thesis was to study properties of oat-based drinks fermented with kefir grains and starter culture. Six oat drink samples with varying sugar contents (2%, 3% and 4%) were fermented with both kefir grains and starter culture for 18 hours at 37 °C. Before fermentation, the titratable acidity, pH and soluble dry matter content (Brix) of the oat drink were measured. After the fermentation process, the same parameters were measured again, and a sensory evaluation was conducted to assess appearance, aroma, taste, texture, sweetness and acidity.
The results of the study revealed that the pH of all samples decreased from the initial level of 7.49±0.046 to a range of 4.59–4.95. The lowest pH was observed in sample KJ 2% (4.59±0.49), which also had the highest titratable acidity (43.87±2.57 °Th). A statistically significant difference in titratable acidity was found between samples KJ 3% and KS 3% (p = 0.0014). The decrease in Brix indicated that microorganisms actively consumed sugar during fermentation. Based on the sensory analysis results, it was found that the starter culture and sugar concentration most strongly influenced the perception of sweetness and acidity. Sample KJ 3% received the highest aroma rating. There were no significant differences in appearance and consistency ratings. The second replicate samples of the kefir grain test were excluded from the sensory evaluation, as the beverage was spoiled in terms of appearance and smell – it had separated strongly, became lumpy, and had an alcoholic odor
The results of this bachelor’s thesis indicate that using starter cultures provides a more stable fermentation outcome. Additionally, the combination of starter culture and sugar concentration affects both chemical and sensory properties. In conclusion, it is possible to create a plant-based kefir alternative from oat drink, though its organoleptic properties still require optimization
Agronomic and bromatological characteristics of Cassava cultivars
No full textReceived: March 12th, 2025 ; Accepted: June 19th, 2025 ; Published: June 26th, 2025 ; Correspondence: [email protected] aim of this study was to evaluate the potential of the aerial part of cassava, analyzing its development and nutritional value, in addition to the production of biomass at different times and with different management. A randomized complete block design was used, with six cassava varieties (BRS Formosa, BRS Mulatinha, Eucalyptus, BRS White Pot, BRS Kiriris and BRS New Horizon) and five replicates, harvested six and twelve months after planting, with and without pruning. To evaluate the amount of biomass produced by the aerial part of cassava and the production of roots, a 6×2 factorial scheme in randomized complete blocks design was conducted. Six cassava varieties were tested, each with five replicates. The plants were harvested at two different times: with pruning (harvesting at six and twelve months after planting) and without pruning (single harvest at twelve months). There was an effect for the characteristics plant height, stem diameter, number of stems, number of leaves, lobe length, lobe width and petiole length, however when they were evaluated at twelve months, there was no effect, only for the characteristics lobe length and petiole length. It was found that there was an effect for dry matter, ether extract, hemicellulose and ADF. The BRS White Pot variety presented a higher concentration of non-fibrous carbohydrates. Differences were observed for neutral detergent fiber corrected for ash and protein and lignin. For the values of total digestible nutrients, the cultivars BRS White Pot, BRS New Horizon and BRS Formosa stood out in relation to the others. There was a difference in the protein fractionation of the different cassava cultivars for total nitrogen fraction, fraction A and fraction C when they were harvested six months after planting. However, when they were evaluated at twelve months, there was only an effect for fraction C. There was an effect for CT, fraction A+B1, fraction B2 and fraction C when they were evaluated six months after planting. However, when they were evaluated twelve months after planting there was no difference for total carbohydrates and fraction B2. The interaction was not significant between the different cultivars and pruning management for the production of green matter, dry matter, crude protein, total digestible nutrients of the aerial part and green matter and dry matter of the roots. In management without pruning, there was an increase in the variables PGMPA, PDMPA, PCPPA and PTDNPA. The cultivars BRS Mulatinha and BRS New Horizon are recommended as they present greater leaf retention and number of stems, providing greater biomass production when managed without pruning
Employees job satisfaction and motivation of Savekate OÜ example
No full textMagistritöö
Ettevõtlus ja ökonoomika õppekavalKäesolev magistritöö käsitleb töötajate töörahulolu ja motivatsiooni ehitusettevõtte Savekate OÜ näitel. Uurimistöö vajadus tuleneb ettevõtte soovist saada süsteemset ja tõenduspõhist ülevaadet töötajate rahulolust ning töötajaid motiveerivatest ja demotiveerivatest teguritest. Teoreetilises osas käsitletakse töömotivatsiooni ja rahulolu olemust ning tuntumaid motivatsiooniteooriaid, sh Herzbergi kahefaktoriteooriat ja Maslow vajaduste hierarhiat. Empiirilises osas viiakse läbi töötajate seas ankeetküsitlus, millele vastas 80,6% ettevõtte töötajatest.
Uuringus selgus, et töötajad peavad kõige olulisemaks konkurentsivõimelist töötasu, lisatasusid ja head meeskonnatööd. Kõige madalamalt hinnati töötajate kaasatust otsustusprotsessidesse ja premeerimissüsteemi läbipaistvust. Sugude ja ametigruppide võrdlus näitas mõningaid statistiliselt olulisi erinevusi, näiteks tajuvad naised tööd tähenduslikumana kui mehed. Ametipositsioonide lõikes ilmnes enim erisusi tasustamisega seotud hinnangutes. Avatud vastustes rõhutati vajadust parema kommunikatsiooni, juhendamise ja tunnustuse järele.
Töö tulemused viitavad vajadusele täiustada tasustamise ja premeerimise süsteemi, arendada juhtide oskusi ning tugevdada sisekommunikatsiooni. Uuring annab praktilisi soovitusi töötajate rahulolu ja motivatsiooni suurendamiseks, aidates ettevõttel kujundada teadlikumat ja töötajakesksemat personalipoliitikat.This master’s thesis examines employee job satisfaction and motivation through the case study of the construction company Savekate OÜ. The need for this research stems from the company’s interest in gaining a systematic and evidence-based overview of employee satisfaction, as well as the factors that motivate or demotivate staff. The theoretical part of the thesis explores the nature of job motivation and satisfaction, including an overview of well-known motivational theories such as Herzberg’s two-factor theory and Maslow’s hierarchy of needs. The empirical part involves a questionnaire survey conducted among the employees, with a response rate of 80.6%.
The survey revealed that employees consider competitive salary, bonuses, and good teamwork to be the most important factors. The lowest ratings were given to employee involvement in decision-making processes and the transparency of the reward system. Comparisons between genders and job groups showed some statistically significant differences; for instance, women perceived their work as more meaningful than men. The greatest differences by job position were related to perceptions of compensation. Open-ended responses highlighted the need for improved communication, guidance, and recognition.
The results indicate the need to improve the compensation and reward system, develop leadership skills, and strengthen internal communication. The study provides practical recommendations for increasing employee satisfaction and motivation, helping the company to shape a more informed and employee-centred human resource policy
A solid wood writing desk at the intersection of design, contemporary construction and material awareness
No full textBakalaureusetöö
Puidutöötlemise tehnoloogia õppekavalTöö eesmärk oli kavandada ja valmistada täispuidust kirjutuslaud, mis oleks huvitava
disainiga ja konstruktsiooniliselt tugev. Tööpind on valmistatud Ameerika saarest ning
jalad mahagonist. Kõik detailid on tehtud ise toorsaematerjalist ja on ühendatud tüüblite
abil ilma metallkinnitusteta. Viimistlemiseks kasutati looduslikku õlivaha.
Konstruktsioon tagab jäikuse ja piisava jalaruumi. Valminud laud sobib käsitöönduslikuks
väiketootmiseks.The aim of this project was to design and build a solid wood writing desk that features an
interesting design and strong structural integrity. The desktop was made from American
ash, and the legs from mahogany. All components were handcrafted from rough-sawn
timber and joined using wooden dowels without any metal fasteners. A natural oil-wax
finish was applied. The construction ensures rigidity and provides sufficient legroom. The
finished desk is suitable for small-scale artisanal production
Morphological and molecular identifications of medically important mosquitoes Culex pipiens and Culex torrentium from specimens collected in the Piusa caves
No full textBakalaureusetöö
Loodusturismi õppekavalPistesääsklased (Diptera: Culicidae) on maailmas laialt levinud putukate sugukond. Paljude liikide emased isendid toituvad püsisoojaste loomade verest, levitades seeläbi erinevaid haigustekitajaid. Töös uuriti, kas talvituvate laulusääse liikide (Cule. pipiens ja Culex torrentium) puhul on tiivaeelsete soomuste esinemine määramistunnusena kasutatav ja usaldusväärne meetod kahe liigi eristamiseks. Lisaks analüüsiti, kas määraja varasem kogemus on oluline faktor liikide eristamiseks. Liikide tuvastamisel lähtusid kõik määrajad samast määramisjuhisest. Kõik määrajad leidsid rohkem Cx. pipiens’i kui Cx. torrentium’i. Morfoloogilitse tulemuste kinnituseks eraldati sääskedest DNA ning analüüsiti polümerisatsiooni ahelreaktsioonil (PCR) kasutades kummagi liigi spetsiifilisi praimereid. PCR analüüsi tulemused olid oluliselt erinevad võrreldes morfoloogiliste tulemustega. Tulemuste põhjal võib järeldada, et töös käsitletud kahe liigi valmikuna talvituvate isendite eristamiseks morfoloogiliselt ei ole tiiva-eelsete soomuste esinemine usaldusväärne määramisfaktor. Täpsemate andmete saamiseks eelmainitud liikide arvukuse ja üleüldise valmikuna talvituvate pistesääsklaste liigirikkuse osas tuleks tulevikus läbi viia suuremahulisem uurimistöö.Mosquitoes (Diptera: Culicidae) are a widely distributed family of insects across the world. Females of many species feed on the blood of warm-blooded animals, thereby transmitting various pathogens. This study investigated whether the presence of prealar scales can be used as a reliable morphological character for distinguishing between two overwintering Culex species, Culex pipiens and Culex torrentium. Additionally, the study analyzed whether the previous experience of the identifier is an important factor in species differentiation. All identifiers followed the same identification key. All identifiers recorded more Cx. pipiens individuals than Cx. torrentium. To confirm the morphological results, DNA was extracted from the mosquitoes and analyzed using polymerase chain reaction (PCR) with species-specific primers for each species. The PCR results differed significantly from the morphological identifications. Based on the results, it can be concluded that the presence of prealar scales is not a reliable morphological character for distinguishing overwintering adult individuals of the two species discussed. To obtain more accurate data on the abundance of the aforementioned species and the overall species diversity of overwintering adult mosquitoes, a more extensive study should be conducted in the future