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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Säsongsrörelser i Bristols slavhandel, 1698-1776.

Kenttä, Tony January 2010 (has links)
<p>This master's essay is about seasonality in Bristols slave trade until the American Revolution 1776. The essay uses the Voyages database as the primary material. The essay's method is to study monthly distribution at different points of the slave trade – the departure from Bristol and the arrival at the American destination. The seasonality of slave purchases in Africa is primarly studied through the monthly distribution of departures from Bristol for a specific region in Africa. This methodological choice is based on the lack of coverage of African arrival dates. The theoretical groundwork in the essay is foremost based on Henri Lefebvre's concept of rhytm analysis. The results of the essay show that there usually was some seasonality in the different parts of Bristol's slave trade. The essay tries to relate this seasonality with possible explanations, like the need of provisions, trade goods, harvest cycles in Africa and America, though the essay doesn't have any pretensions of proving actual causal relations, just that the seasonality of the slave trade coincided with other seasonal cycles.</p>
2

Säsongsrörelser i Bristols slavhandel, 1698-1776.

Kenttä, Tony January 2010 (has links)
This master's essay is about seasonality in Bristols slave trade until the American Revolution 1776. The essay uses the Voyages database as the primary material. The essay's method is to study monthly distribution at different points of the slave trade – the departure from Bristol and the arrival at the American destination. The seasonality of slave purchases in Africa is primarly studied through the monthly distribution of departures from Bristol for a specific region in Africa. This methodological choice is based on the lack of coverage of African arrival dates. The theoretical groundwork in the essay is foremost based on Henri Lefebvre's concept of rhytm analysis. The results of the essay show that there usually was some seasonality in the different parts of Bristol's slave trade. The essay tries to relate this seasonality with possible explanations, like the need of provisions, trade goods, harvest cycles in Africa and America, though the essay doesn't have any pretensions of proving actual causal relations, just that the seasonality of the slave trade coincided with other seasonal cycles.
3

Dejefors kraftverks inverkan på den lekvandrande laxens möjlighet till nedströmsvandring i Klarälven / Downstream salmon kelt migration past Dejefors hydropower plant in the river Klarälven

Hansson Järnving, Rebecca January 2021 (has links)
Under hösten leker en inhemsk population av Atlantisk lax (Salmo salar) i Klarälven, Sverige, för att därefter vandra nedströms tillbaka till sjön Vänern. Vid älvens andra kraftverk sett från Vänerns mynning, Dejefors kraftverk, finns det planer på att ersätta ett av kraftverken mot ett nytt och det finns därför ett behov av att ta reda på hur laxens nedströmsvandring påverkas av det kraftverket som finns där i dag. Då alla kraftverk i Klarälven saknar fiskpassagelösningar är det extra viktigt att följa upp laxarnas passageöverlevnad under vandringen. Avsikten med denna studie var därför att ta reda på hur laxen rörde sig runt kraftverket, hur väl de klarade av att passera kraftverket beroende av vilken passageväg de tog och vilka faktorer som påverkade passageframgången. Under september 2020 fångades 40 laxindivider in när de var på väg uppströms inför leken. De mättes och märktes med telemetrisändare för att sedan transporteras uppströms och släppas ut nedanför kraftverket i Munkfors, varifrån deras nedströmsvandring förbi Dejefors kraftverk följdes och analyserades med hjälp av akustisk telemetri. Resultatet visade att det inte fanns någon signifikant skillnad mellan kön för när laxarna påbörjade sin nedströmsvandring. Kraftverket visade sig dock fördröja laxarnas nedströmsvandring då det tog längre tid för dem att passera kraftverket än vad det tagit dem att simma ner dit i den fritt strömmande delen av älven. Av de 31 laxar som anlände till Deje så passerade 27 av dem kraftverket, varav 13 individer överlevde (48 %). Överlevnaden var högre för individer som passerade via spillutskoven (10 av 12) än turbinerna (3 av 15). Det fanns en signifikant skillnad i mortalitet vid kraftverkspassage beroende på laxens längd och passageväg; långa individer hade en högre mortalitet (73 %) än kortare (25 %) och passagevägen hade en signifikant effekt på mortaliteten. Resultatet visar tydligt på ett behov av åtgärder för att förbättra överlevnaden hos lax vid passage av Dejefors kraftverk. Lösningar för att få fisken att helt undvika turbinerna och istället välja en annan passageväg vore troligen den bästa och effektivaste lösningen för att öka laxens överlevnad under nedströmsvandringen. / During autumn, the endemic Atlantic salmon (Salmo salar) migrate upstream to spawn in the river Klarälven, Sweden, after which they migrate downstream back to Lake Vänern. There are plans to remove one of the power houses in Deje, and replace it with a new power house, and before that happens it is important to study the downstream passage conditions at the site. As all power plants in Klarälven lack fish passage solutions, it is important to follow up the salmon passage survival during the migration. The purpose of this study was therefore to study how downstream migrating salmon negotiate the power plant, the route-specific passage survival and what factors that could affect their passage success. In September 2020, 40 upstream migrating salmon individuals were caught, measured and tagged after which they were transported and released below the power plant in Munkfors. Their downstream migration past Dejefors power plant was studied and analyzed using acoustic telemetry. The results showed that there was no significant difference between sexes in regards of downstream migration timing. However, the power plant turned out to delay downstream migrating salmon as it took longer time for them to pass the power plant than it took them to swim down the free-flowing part of the river. Of the 31 salmon that arrived in Deje, 27 passed the power plant, of which 13 individuals survived (48%). The survival rate was higher for individuals passing via spillways (10 of 12) than turbines (3 of 15). There was a significant difference in mortality rate at power plant passage depending on the length and passage route of the salmon. Large individuals suffered a higher mortality (11 of 15) than short (3 of 12) and a larger proportion of the salmon died when passing through the turbines than through spill gates. Based on the results, there was a clear need for improved survival rates for salmon passing the Dejefors power plant. The design of the turbines could be changed for increased survival, but at the same time other solutions that will make it possible for fish to avoid the turbines and instead choose another passageway would probably be a better and more efficient solution to increase the survival of the salmon during their downstream migration.

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