• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 8
  • 2
  • 2
  • Tagged with
  • 15
  • 5
  • 5
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 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

The Glycemic and Insulinemic Effects of Short-Term Blood Flow Restricted Walk Training

Osborne, Larry A., Jr. 11 July 2018 (has links)
No description available.
2

Effect of Cuff Pressure on Blood Flow During Blood Flow-Restricted Rest and Exercise

Crossley, Kent Westerberg 01 April 2019 (has links)
Purpose: The purpose of this study was to investigate the blood flow/pressure relationship (linear or nonlinear) in the superficial femoral artery when seated, as well as to investigate blood flow changes with exercise using varying cuff pressures and a preexercise (PE) condition. The presence of venous outflow with occlusion at rest and exercise was also investigated.Methods: Twenty-three subjects visited the lab on 3 occasions. First to determine linearity of blood flow using 0% to 90% arterial occlusion pressure (AOP), and venous outflow at rest and during exercise with cuff inflated to 40% AOP. Subsequent visits compared blood flow between rest and PE conditions to determine average blood flow, heart rate, systolic and diastolic blood pressure changes in response to a blood flow-restricted (BFR) exercise protocol. Results: Blood flow/pressure relationship is nonlinear at the superficial femoral artery (p < 0.01). No significant differences in average blood flow, conductance or mean arterial pressure (MAP) were found between 30% to 80% AOP (p = 1.0 to .08). Blood flow is not significantly different between rest and PE groups (p = 0.49) although initial 40% AOP and 40% exercise arterial occlusion pressure (EAOP) values were different between rest and PE groups. (p < 0.01). Conclusion: The nonlinear relationship at the superficial femoral artery demonstrates higher cuff pressures are not necessary to reduce blood flow in BFR exercise of the lower extremity. Furthermore, PE or warm-up is not necessary prior to determining EAOP as it does not alter blood flow responses during BFR exercise. We found evidence of venous outflow above the cuff both at rest and during exercise at 40% AOP.
3

Exponering för bromerade flamskyddsmedel vid arbete med flygplansunderhåll

Lundgren, Håkan January 2013 (has links)
Problemställning och syfte: Bromerade flamskyddsmedel (BFR) används i många varor och produkter. Polybromerade difenyletrar (PBDEs) är en av dessa och deras kemiska struktur liknar den i miljögiftet PCB och kan på samma sätt lagras upp i miljön samt skada människor och djur. På arbetsplatser där BFR förekommer riskerar medarbetarna att exponeras. I den här studien har olika BFR undersökts i samband med servicearbete på flygplan. Målet har varit att jämföra förekomsten i damm och luft, samt blod (serum) med resultat från tidi­gare studier. Metod: Damm- och luftprovtagning har genomförts vid olika faser av service­arbetet. Proverna har analyserats med avseende på olika typer av BRF. Dess­utom har medarbetarnas upptag av BRF via blodprov (serum) undersökts. Resultat: Undersökningen har visat att samtliga former av PBDE samt övriga BFR förekommer i höga koncentrationer i damm och luft i flygplanen, men med ojämn fördelning. Analyserna av serum visade att flygmekanikerna har förhöjda nivåer jämfört med svensk allmänhet och jämförbar nivå med högexponerade yrkesgrupper. Medarbetarnas ålder, år i yrke och arbetad tid i flygplan den senaste månaden uppvisade inget samband i förhållande till PBDE i serum. Slutsats: Koncentrationerna av BFR i damm och luft är högre än i de flesta andra miljöer och koncentrationerna i serum är högre än de flesta referens­gruppers. För att minska risken för exponering behöver insatserna för att mini­mera dammet via städning förbättras. Dessutom bör informationen gällande hygien och användning av personlig skyddsutrustning repeteras för medarbe­tarna. Samtliga yrkeshygieniska åtgärder bör fastställas och hanteras i det systematiska arbetsmiljöarbetet via rutiner och handlingsplaner. / Presentation and aim: Brominated flame retardants (BFRs) are used in many materials and products. Polybrominated diphenyl ethers (PBDEs) are the most well known and because of their structures, similar to that of PCB, they have been proposed to possibly affect health and environment. Occupational exposure has been an issue for years and this study investigated BRF in aircraft mainte­nance. The aim of this study was to assess the presence and levels of BRFs in dust, air and blood (serum) and compare the results with different references. Method: Dust and air were sampled in different phases of the work with the air­craft and analysis of a spectrum of BFR was performed. In addition, serum from employees was sampled and analyzed for the presence of PBDEs. Result: PBDEs and other BFRs were found in dust and air samples at high con­centrations. Serum concentrations in the technicians were slightly higher to those observed in the general Swedish population and in the same magnitude as some highly exposed occupational references. Years of work, age or time spent in the aircraft before giving blood seems not to have an impact on the level of BFRs in serum. Conclusion: This study shows high concentrations of BFR in dust and air in the aircraft and the concentrations of PBDEs in serum were high compared to most reference groups. To minimize the risk for exposure, it is important to focus on industrial hygiene improvements to minimize the amount of dust in working areas. The personal hygiene and use of personal safety equipment can also be improved and the routines should be described and included in the appropriate documentation regarding work environment.
4

Aluminium water extract levels from liquid packaging board : A comparative trial study between alum and polyaluminium chloride added as flocculants on BM7, Stora Enso Skoghall Mill / Vattenextraktnivåer av aluminium från vätskekartong : En jämförande försöksstudie mellan alun och polyaluminiumklorid tillsatt som flockningsmedel på KM7, Stora Enso Skoghalls Bruk

Cassel, Hanna January 2022 (has links)
The aluminium content of water extracts is an important aspect for the food safety of paper board, as the content indicates the ability of the paper board material to transfer aluminium to the packaged food product. Aluminium intake in humans and its health effects have been discussed for many years as some research has seen potential links between, among other things, high aluminium levels in the brain and the development of hereditary Alzheimer's.BfR's method and recommendation is the one that is generally followed by producers around the world, as there is no common international law. The method involves leaving small pieces of the paper board in Milli-Q water for 24 hours, before a content determination of Al is made in the formed water extract. In 2021, BfR halved its recommended limit for aluminium in aqueous extracts from 2 mg/L to 1 mg/L. For Stora Enso Skoghall, this led to some of their paper board grades not meeting this limit.A specific liquid packaging board grade that previously did not meet BfR's new limit was selected and alum as a flocculant was replaced with PAC, among other things. The aim was to investigate whether the change in flocculation chemical, as well as varying dosages, could affect the Al content in water extracts and whether PAC could possibly result in a lower Al content. The method for the water extracts and their effect on the final Al content have also been investigated further. This is done by performing the BfR method with artificial tap water as well, and then comparing the Al content in these extracts.PAC as a flocculant instead of alum did not result in lower levels of Al in the water extracts. Variations in dosage and production without aluminium-containing flocculants also did not significantly affect the Al content of the extracts. The type of water used in the analysis turned out to play a major role in how much aluminium migrated from the board. All samples extracted in artificial tap water resulted in Al levels less than the 1 mg/L limit. For the majority of the samples extracted in Milli-Q water, the Al levels were instead closer to 2 mg/L. The difference in Al content between the water extracts is believed to be mainly due to differences in pH and thus varying amounts of soluble aluminium.The results showed a relatively large variation between the two external laboratories used. This is believed to be mainly due to variations in method and measuring equipment, but one must also consider the small sample size that was tested and what variations it entails.
5

An automated approach to clustering with the framework suggested by Bradley, Fayyad and Reina

Berglund, Jesper January 2018 (has links)
Clustering with the framework suggested by Bradley, Fayyad and Reina allows for great scalability. However, practical challenges appear when applying the framework. One of the challenges is to define model parameters. This includes defining the number of clusters (K). Understanding how parameter values affect the final clustering may be challenging even with insight into the algorithm. Automating the clustering would allow for a more widespread use. The research question is thus: How could an automated process for clustering with BFR be defined and what results could such a process yield? A tailored method for parameter optimization is suggested. This method is used with a new and computationally advantageous cluster validity index called population density index. Computing the widely used within set sum of squares error requires an additional pass over the data set. Computing population density index does not. The final step of the automated process is to cluster with the parameters generated in the process. The outcome of these clusterings are measured. The results present data collected over 100 identically defined automated processes. These results show that 97 % of the identified K-values falls within the range of the suggested optimal value 2. The method for optimizing parameters clearly results in parameters that outperform randomized parameters. The suggested population density index has a correlation coefficient of 1.00 with the commonly used within set sum of square error in a 32-dimensional case. An automated process for clustering with BFR has been defined. / Ramverket som föreslås av Bradley, Fayyad och Reina möjliggör storskalig klustring. Att använda ramverket medför dock praktiska utmaningar. En av dessa utmaningar är att definiera modellens parametrar. Detta inkluderar att definiera antalet kluster (K). Att förstå hur angivna parametervärden påverkar det slutgiltiga klustringsresultatet är utmanande även med insikt i algoritmen. Att automatisera klustringen skulle möjliggöra för fler att använda ramverket. Detta resulterar i frågeställningen: Hur skulle en automatiserad process för klustring med BFR kunna definieras och vilka resultat skulle en sådan process kunna ge? En skräddarsydd metod för parameteroptimisering föreslås. Denna används i kombination med ett nytt klustervalideringsindex vilket refereras till som population density index. Användning av detta index medför beräkningsmässiga fördelar. Att beräkna det frekvent använda within set sum of squares-värdet kräver ytterligare en iteration över det använda datasettet. Att beräkna population density index undviker denna extra iteration. Det sista steget i den automatiserade processen är att klustra givet de parametervärden som processen själv definierar. Resultatet av dessa klustringar mäts. Resultaten presenterar data insamlad över 100 individuella försök. För samtliga av dessa var den automatiserade processen identiskt definierad. Resultaten visar att 97 % av de identifierade värdena på K-parametern faller inom en värdemängd baserad på det optimala värdet 2. Att optimera parametervärden med den föreslagna metoden ger tydligt bättre värden än om dessa genereras stokastiskt. Det föreslagna population density index har 1.00 som korrelationskoefficient med det välanvända within set sum of squares-värdet i ett 32-dimensionellt fall. En automatiserad process för att klustra med BFR har definierats.
6

Fate Mechanisms and Removal of Tetrabromobisphenol-A (2,2’,6,6’-Tetrabromo-4,4’-isopropylidenediphenol) in the Activated Sludge Process

Potvin, Christopher Michael 10 May 2012 (has links)
A novel method for determination of tetrabromobisphenol-A (TBBPA), was developed using gas chromatography-negative ion chemical ionization-mass spectrom- etry (GC-NCI-MS). Samples of municipal wastewater treatment plant (WWTP) influent were analyzed for TBBPA. Levels ranged from 1 to 41 ng/L, with an average of 20 ± 14 ng/L. Matrix effects were shown to be 30 ± 17 % in the influent and -30 ± 11 % in membrane permeate. The method limit of quantitation was 0.1 ng/L TBBPA. Sorption of TBBPA to fresh mixed-liquor suspended solids (MLSS) from a membrane bioreactor (MBR) were studied. In a kinetic study, sorption was found to be essentially complete after 12 hours of exposure to MLSS. Log Koc and log Kd were measured at 4.7 ± 0.8 and 1.9 ± 0.8 respectively (n = 22). These values were much higher than modelled estimates based on Kow (p ≥ 0.05), and higher than modelled estimates based on Kow and pKa (p ≥ 0.05). Data was successfully modelled using the Freundlich isotherm, having a Kf value of 8.5 and an n value of 1.7. TBBPA adsorbed to borosilicate glassware, with a wall-loss coefficient (Kw) of 0.15 ± 0.1 (n ≥ 3). TBBPA levels in WWTP influent varied from 13 to 29 ng/L while effluent concentrations varied from 0 to 2.2 ng/L over the same period. Three pilot-scale membrane bioreactors (MBRs) removed less TBBPA during the same time period, though MBR removal was also significant (p ≥ 0.05). Increasing MBR sludge residence time (SRT) increased removal at the 86 % confidence interval (p = 0.14). A nitrifying MABR was shown to remove TBBPA significantly when spiked with ammonia and TBBPA (p ≥ 0.05), showing that nitrifying bacteria can degrade TBBPA. An MABR hollow fibre was found to adsorb TBBPA. Various soluble microbial products (SMP) were studied from MBRs fed munici- pal influent. Using current measurement practices, SMP were shown to be sensitive to matrix effects. Use of the standard addition technique (SA) can compensate for this. Measurements using SA showed SMP degrades rapidly during storage in the fridge and due to freezing. SA was also used to compare commonly used SMP extraction techniques, and showed that extraction method influences recovery.
7

Hormonstörande ämnen i förskolans inomhusmiljö : Inventering av privata förskolor i Östersunds kommun och förslag till förbättringsåtgärder

Ros, Julia January 2015 (has links)
I dagens moderna samhälle finns syntetiska kemikalier i princip överallt. De kan tas upp av människor på olika sätt, till exempel genom inandning, upptag genom huden och genom mat. Barn och unga är mer känsliga för kemikalier än vuxna, bland annat eftersom hjärnan, immun- och hormonsystemet inte är färdigutvecklade. Studier har visat höga halter av olika kemikalier i förskolemiljön vilket tros bero på de olika material som ofta förekommer, såsom skumgummi och plast, samt mängden av dessa. Studiens främsta syfte är att göra en uppskattning av exponeringen för bromerade flamskyddsmedel, ftalater och bisfenol A i de privata förskolorna inom Östersund kommun, samt ge förslag till förbättringsåtgärder. Metoden omfattar en inventering av förskolorna samt en litteraturstudie som fokuserar på relevant forskning om ämnena i fokus. Data från inventeringen rörande material och produkter kända att innehålla bromerade flamskyddsmedel, ftalater och bisfenol A plockades ut och utvärderades. Datan delades in i kategorierna skumgummi, mjukgjord plast, samt äta – produkter i plast. Information om några av de återförsäljare som förskolorna handlat av har samlats in. Utifrån det litteraturstudien och inventeringen visat har förslag till förbättringsåtgärder tagits fram. Resultatet visar att material och produkter kända att innehålla bromerade flamskyddsmedel, ftalater och bisfenol A förekom i relativt stor utsträckning på flera av förskolorna. Skillnaderna i mängd material och produkter mellan förskolorna var dock väldigt stora. Möjliga förklaringar är olika pedagogiska inriktningar samt olika grad av medvetenhet om risker med till exempel plast. En jämförelse med en inventering av kommunala förskolor i en annan kommun visar att förskolorna i denna studie generellt sett hade mindre mängd skumgummi, mjukgjord plast i inredning och leksaker, samt muggar och tallrikar i plast. Skillnaden kan eventuellt bero på att privata förskolor inte är bundna att följa kommunens upphandling. Ytterligare studier behövs för att kunna uppskatta vidden av exponering för bromerade flamskyddsmedel, ftalater och bisfenol A i Östersunds privata förskolor, samt för att göra en bedömning av eventuell påverkan på barns hälsa.
8

Linking exposure pathways to internal concentrations of brominated flame retardants in Swedish mothers and their toddlers

Sahlström, Leena January 2014 (has links)
Brominated flame retardants (BFRs) have been used in a variety of consumer products to enhance their fire safety. This has resulted in exposure of the environment, wildlife and humans causing risks of endocrine disruption. The use restrictions of many BFRs have resulted in the introduction of other brominated chemicals (emerging BFRs) on the market. Humans are exposed to BFRs primarily via diet and dust ingestion, but the importance of the different exposure pathways has scarcely been studied. Children in particular have not been studied well due to lack of biomonitoring data. In this thesis, a mother-toddler cohort (n=24) from Uppsala was studied for their exposure to tri-decabrominated diphenyl ethers (tri-decaBDEs), isomer-specific hexabromocyclododecanes (HBCDs) and emerging BFRs (EBFRs). A clean-up and fractionation method was developed for determination of the above-mentioned BFRs in the same sample without dividing the sample. Measures of external exposure from dietary intake and dust ingestion were estimated. These were compared to internal concentrations (serum, feces) to determine which exposure pathways were most important for explaining the different BFR concentrations and patterns found in mothers and toddlers. Taking all the results into account, the toddlers’ higher serum levels of tetra-pentaBDEs seem to be the result of previous breastfeeding and those of octa-decaBDEs from exposure to house dust. For mothers, diet was estimated to be the main exposure route of tri-hexaBDEs and HBCDs. Dust ingestion was estimated to be the main route for BDE-209 exposure in mothers. Significant correlations were found between the tetra-decaBDE concentrations in matched serum and feces samples indicating that feces could be used as a non-invasive sample matrix for biomonitoring of PBDEs in toddlers. EBFRs were detected in the feces of toddlers and in a few serum samples from both mothers and toddlers indicating that exposure to these replacement chemicals occurs. / <p><strong> </strong>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.</p>
9

Corrosion-related Gas Measurements and Analysis for a Suite of Coals in Staged Pulverized Coal Combustion

Reeder, Todd A. 30 June 2010 (has links) (PDF)
Eleven gas species, including CO, CO2, H2, H2O, H2S, HCl, NOX, O2, SO2, COS and SO3, were measured in a 150 kWth, staged, pulverized coal, down-fired combustor using a Fourier transform infrared (FTIR) spectrometer, gas chromatograph (GC), and a Horiba PG-250 5-gas analyzer. Additional gases such as HCN, NH3, CH4, and other hydrocarbons were also measured. Seven coals of varying rank and composition were investigated. Measurements were obtained in reducing (S.R. = 0.85) and oxidizing (S.R. = 1.15) conditions. In particular, sulfur- and chlorine-containing species including H2S, SO2, COS, SO3, and HCl are discussed. In the reducing zone, all four measured sulfur species were present although SO3 was only 1-3% of the total coal sulfur. A trade-off between SO2, H2S, and COS was clearly identifiable according to S.R. H2S and COS increased and SO2 decreased in highly reducing or high-CO regions. The total amount of sulfur in the measured species in the reducing zone was estimated to be about 65-80% of the total coal sulfur. The total amount of sulfur measured in the four gases increased linearly with coal sulfur in both the oxidizing and reducing zones for the seven coals considered. In the oxidizing zone, SO3 remained low (1-3% of total sulfur) with the only other measurable sulfur bearing species being SO2. Chlorine was found to be released in the reducing zone and form primarily HCl. As the HCl was transported into the oxidizing region, the chlorine remained as HCl. Measurement of HCl was difficult, making some of the data incomplete. The HCl concentration was found to be affected by the flow rate of gases into the sampling line and gas analyzers suggesting HCl is highly reactive and needs to be quenched rapidly or it will react during sampling. Several trends in the data were matched by equilibrium calculations including trends for H2S, COS and SO2 in both reducing and oxidizing conditions. SO3 did not match equilibrium although the amount of SO3 was proportional to the amount of sulfur in the coal. HCl, though consistent with cited literature for several coals, did not agree with equilibrium trends or values.
10

The Effects of Common Low-load Blood Flow Restriction Training Protocols on Muscle Excitation and Fatigue

Aldeghi, Taylor M 01 January 2022 (has links)
Low-load blood flow restriction (LLBFR) training has been shown to elicit greater increases in muscle hypertrophy and strength compared to traditional low-load training, yet few studies have compared the effectiveness of different LLBFR protocols. To our knowledge, no previous study has compared the acute neuromuscular changes induced by two common LLBFR protocols: 30-15-15-15 repetitions (BFR-75) and four sets of repetitions performed to volitional failure (BFR-F). Therefore, the purpose of this study was to use surface electromyography (sEMG) to compare changes in muscle excitation and fatigue during BFR-75 and BFR-F protocols. Ten women (mean ± SD age = 22 ± 3.5 years) volunteered to participate in this investigation. Participants performed isokinetic, unilateral, concentric-eccentric, leg extension muscle actions at 30% maximal voluntary isometric contraction torque with BFR applied at 60% arterial occlusion pressure using a 12-centimeter-wide cuff. The sEMG amplitude and frequency values were measured from the rectus femoris muscle during the beginning and end of each set of exercise and analyzed using separate 2 [condition (BFR-75 and BFR-F)] x 8 [time (B1, E1, B2, E2, B3, E3, B4, E4)] repeated measures ANOVAs. For sEMG amplitude, there was no significant 2-way interaction (p = 0.486; ηₚ² = 0.118) or significant main effect for condition (p = 0.617; ηₚ² = 0.038), but there was a significant main effect for time (p < 0.001; ηₚ² = 0.520). SEMG amplitude increased across time during both protocols (B1 < E1, E2, B3, E3, B4, E4, p ≤ 0.001–0.049). For sEMG frequency, there was no significant 2-way interaction (p = 0.847; ηₚ² = 0.064) or significant main effect for condition (p = 0.825; ηₚ² = 0.007), but there was a significant main effect for time (p = 0.006; ηₚ² = 0.478). SEMG frequency decreased across time during both protocols (B1 > E1, B2, E2, B3, E3, B4, E4, p = 0.002–0.035). Thus, the implementation of the BFR-75 and BFR-F protocols elicited comparable neuromuscular responses that were consistent with fatiguing exercise, but investigators and clinicians may consider other factors such as participant/patient comfort, time, and rating of perceived exertion when determining which protocol to use.

Page generated in 0.0639 seconds