Salmonella enterica serotypes have been linked to outbreaks associated with low water activity foods. The ability of biofilm forming pathogens, such as Salmonella, to survive thermal and chemical processes is improved; it is unclear if biofilms will also improve survival to desiccation and gastric stresses. The purpose of this study was to quantify the effect of physiological state (planktonic versus biofilm) and prior exposure to desiccation on Salmonella survival and gene expression after passage through an in-vitro digestion model. Cells of Salmonella enterica serotype Tennessee were deposited onto membranes for planktonic cells or on glass beads to create biofilms. The cells were subsequently dried at room temperature and stored in dried milk powder (aw = 0.3) for up to 30 days. Salmonella survival was quantified by serial dilution onto brilliant green agar before desiccation, after desiccation, after 1-day storage and after 30-day storage. At each sampling both physiological states were tested for survival through a simulated gastrointestinal system. RNA was extracted at the identical time points and relative gene expression determined for genes associated with stress response (rpoS, otsB), virulence (hilA, hilD, invA, sipC) and a housekeeping gene 16S rRNA using quantitative real-time PCR. The physiological state and length of storage effected the survival and gene expression of Salmonella within the desiccated milk powder environment and after passage through an in-vitro digestion system (p<0.05). Larger numbers of S. Tennessee were recovered by plate counts for biofilm cells, compared to planktonic cells. However, the numbers of 16S rRNA gene copies were not significantly different suggesting entry of S. Tennessee into a viable but non-culturable state. Prolonged storage in dry milk powder was not associated with increased cross-protection to gastric stress. Increased expression of stress response genes rpoS and otsB correlated with survival, indicating cross protection of low water activity and acid stress. Increased expression of virulence-associated genes was seen in cells exposed to short periods of dry storage, suggesting an increased virulence potential. / Master of Science in Life Sciences

Radio frequency interference (RFI) poses significant challenges for passive microwave radiometry used in climate studies and Earth science. Despite operating in protected frequency bands, microwave radiometers often encounter RFI from sources like air surveillance radars, 5G communications, and unmanned aerial vehicles. Traditional RFI detection methods rely on handcrafted algorithms designed for specific RFI types. This study proposes a deep learning (DL) approach, leveraging convolutional neural networks to detect various RFI types on a global scale. By learning directly from radiometer data, this data-driven method enhances detection accuracy and generalization. The DL framework processes raw moment data and Stokes parameters, dynamically labeled using quality flags, offering a robust and efficient solution for RFI detection. This approach demonstrates the potential for improved RFI mitigation in passive remote sensing applications.

As the population increases, Swedish cities are becoming more urbanized. Consequently, people’s well-being deteriorates, and global warming has become reality. Buildings are replacing green spaces, necessitating the implementation of new methods to reintroduce greenery into urban areas. This study was conducted to investigate how a wall of an existing building in Halmstad, Sweden, is affected by supporting a living wall concerning load-bearing capacity, moisture, energy performance and economics. The methodology of this qualitative study includes literature review, interviews, and calculations for moisture, heat, and load-bearing capacity. The study found that living walls serve as additional insulation and that moisture does not affect the existing wall due to a vapor barrier. Also that the calculated wall withstands the weight of the living wall. Installation and maintenance costs can vary widely, and there is a wide range of plant species available. It's important to find plants that can withstand the climate for the specific wall. A broader selection of plants is available among those that wither in a beautiful way and are thus not evergreen. After interviews, it can be noted that living walls require minimal maintenance and thus maintenance costs are constant. Over time, some costs will be reduced as cooling and heating expenses decrease since the living wall acts as additional insulation.

The regeneration in oak-dominated stands following five silvicultural treatments was examined on four sites in the mountains of Virginia and West Virginia. Treatments included: silvicultural clearcut, leave-tree, commercial clearcut, shelterwood, and group selection. The effects of harvesting were compared among sites and among treatments. Oak regeneration dominance, measured by the relative density of dominant and codominant oak regeneration, was the most important variable calculated from the data. Oak regeneration dominance varied by site, but did not vary by silvicultural treatment; all treatments resulted in relatively low numbers. Therefore, the silvicultural treatments used here were not enough to overcome the site specific limitations to successful oak regeneration. Oak species also seemed to be less important in the regenerating stands than in their parent stands. The biggest losses in oak importance occurred on the intermediate and high quality sites; competitive oak regeneration was relatively scarce on two of the three sites with an oak site index (base age 50) of over 70 ft. Multiple linear regression analysis was used to identify the factors controlling oak regeneration at a smaller scale. The most important variables were those that described the oak stump sprouting potential, the understory and overstory oak component in the pre-harvest stand, post-harvest light and soil nitrogen levels. / Master of Science

<p dir="ltr">Historically, low-moisture foods were considered to have minimal microbial risks due to their inability to support the growth of microorganisms. However, many high-profile multistate outbreaks and recalls have drawn research and extension attention to low-moisture food safety. Contamination can occur at any stage in the supply chain, making food safety a shared responsibility among all actors from farm to fork. Fostering a positive food safety culture is essential for implementing food safety management systems, ensuring compliance, and driving the adoption of food safety-enhancing technologies, ultimately improving food safety performance across the industry. This dissertation explores the factors and best practices influencing cultural and managerial transformation in food safety and identifies challenges and needs in food safety training, education, and management, among various stakeholders in the low-moisture food industry. Chapters 2 and 3 focus on the California almond industry as a case study. Chapter 2 showcases the evolution of food safety management and culture in the almond industry following two major <i>Salmonella </i>outbreaks in the early 2000s, highlighting the role of repeated outbreaks and proactive industry leadership in driving the changes. It also examines the factors affecting the industry-wide adoption of food safety technologies. Chapter 3 evaluates current food safety training programs in almond processing facilities, detailing key advancements and barriers to effective training. Their user experiences with current food safety materials are also assessed to identify areas for improvement. Chapter 4 expands the assessment to the broader U.S. low-moisture food industry, investigating best practices and barriers in improving food safety culture, and assessing challenges and data gaps in continual food safety improvement. Moving further downstream in the supply chain, Chapter 5 shifts focus to retail food establishments, specifically Asian restaurants, exploring their handling practices of dried wood ear mushrooms, a culturally unique low-moisture food ingredient implicated in a multistate <i>Salmonella</i> outbreak in 2020 and multiple recalls. This chapter also uncovers the unique challenges to behavioral change within this niche audience, such as cultural practices and language barriers. Findings from these studies provide valuable insights into the dynamics and complexities of cultural transformation in the food system. They also inform the development and improvement of culturally tailored training and educational programs, and guide future research directions, continuously strengthening food safety culture and performance in the low-moisture food sector.</p>

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The present work is a contribution to description and understanding of the distribution and movement of water in swelling soils. In order to investigate the moisture distribution in swelling soils a detailed knowledge of volume change properties, flow characteristics and total potential of water in the soil is essential. Therefore, a possible volume change mechanism is first described by dividing the swelling soils into four categories and volume change of a swelling soil is measured under different overburden pressures. The measured and calculated (from volume change data) overburden potential components are used to check the validity of the derivation of a load factor, ∝. Moisture diffusivity in swelling soil under different overburden pressures is measured using Gardner's (1956) outflow method. Behaviour of equilibrium moisture profiles in swelling soils is theoretically explained, solving the differential equation by considering the physical variation of individual soil properties with moisture content and overburden pressure. Using the measured volume change data and moisture potentials under various overburden pressures, the behaviour of possible moisture profiles are described at equilibrium and under steady vertical flows in swelling soils. It is shown that high overburden pressures lead to soil water behaviour quite different from any previously reported.

Veckbildning i bitumenbaserade tätskiktmattor är ett problem som är känt i branschen. Problemet uppstår oftast på underlagstak av trä som är byggda under årets fuktigaste period, oktober-november, och vecken börjar då att bildas i slutet av våren i takt med den ökande solinstrålningen. Vecken bildas när underlagstaket torkar ut och krymper, det leder till att tätskiktets infästningspunkter skjuts ihop och ett materialöverskott av tätskiktsmatta bildas – ett tillräckligt stort materialöverskott visar sig i form av ett veck. Idag kan veckbildningen leda till att tätskiktsmattor måste bytas ut av estetiska skäl. Denna rapport utreder vilka faktorer som påverkar risken för veckbildning. Rörelser i både trä och tätskikt har studerats. Träets rörelser är direkt beroende av dess fuktkvot, när träet torkar ut krymper det också. För att utreda de faktorer som påverkar träets fuktighet har fuktberäknings-programmet WUFI använts. WUFI har nyttjats för att göra en parameterstudie där olika parametrar har jämförts, till exempel: platser i landet, inbyggnadsfuktkvoter, tidpunkter för inbyggnad etc. Till skillnad från de flesta andra material krymper bitumenbaserade tätskikt initialt till följd av uppvärmning från solen. Hur träet och tätskiktet påverkar varandra till följd av deras inbördes rörelser har utretts i form av en hypotes. Antagandet utgår från att tätskiktets mekaniska infästningspunkter i underlagstaket är en viktig del - ju kortare avstånd mellan infästningspunkterna, desto högre är risken för veckbildning. Beräkningar, utifrån antagandet, har gjorts för att kunna jämföra olika utföranden med varandra. Faktorer som leder till minskad risk för veckbildning är att minska fuktkvotsändringen och därmed fuktrörelserna genom att bygga tak med så låg inbyggnadsfuktkvot som möjligt, till exempel genom att bygga under våren/sommaren. Vid byggnation under höst/vinter kan fuktkvoten hållas nere med en avfuktare. Att använda takplywood i stället för råspont leder till minskade rörelser i underlagstaket. En annan åtgärd som skulle minska risken för veckbildning är att öka den maximalt tillåtna krympningen i tätskiktet. / Creasing in roofing membranes is a problem that is familiar in the industry. The issue usually occurs on wooden roof deckings constructed during the wettest period of the year, October-November. The creases then begin to form at the end of the spring due to the increasing solar radiation. When the roof decking dries out and shrinks, the creases start to form. The shrinking leads to the attachment points of the roofing membrane getting pushed together. That creates an excess of material - a sufficiently large surplus of material appears in the form of a crease. Today, the formation of creases can lead to roofing membranes having to get replaced for aesthetic reasons. This report investigates the factors that affect the risk of creasing. Both the movement in the wood and the roofing membrane have been examined. The wood's motions are directly dependent on its moisture content. When the wood is drying, it's also shrinking. The moisture calculation program WUFI has been used to investigate the factors that affect the wood's moisture. The investigation is in the form of a parameter study where different parameters have been compared, for example, places in the country, built-in moisture ratios, built-in times, and more. Unlike most other materials, bituminous roofing membranes initially shrink due to heating from the sun. How the wood and the roofing membrane affect each other as a result of their respective movements has been investigated in the form of a hypothesis. It assumes that the mechanical attachment points of the roofing membrane in the roof decking are of importance - the shorter the distance between the attachment points, the higher the risk of creases. Calculations, based on the assumption, have been made to compare different roofing components with each other. Factors that lead to a reduced risk of creasing are to reduce the moisture ratio change and thus the moisture movements by building roofs with as low a built-in moisture ratio as possible, for example, by constructing in the spring/summer. When constructing during autumn/winter, the moisture ratio can be kept down with a dehumidifier. Using roof plywood instead of tongued and grooved board leads to reduced movements in the roof decking. Another measure that would reduce the risk of creasing is to increase the maximum allowable shrinkage in the roofing membrane.

Doctor of Philosophy / Department of Civil Engineering / Mustaque Hossain / The engineers from the Kansas Department of Transportation (KDOT) often have to decide whether or not to accept non-conforming Superpave mixtures during construction. The first part of this study focused on estimating lives of deficient Superpave pavements incorporating nonconforming Superpave mixtures. These criteria were based on the Hamburg Wheel-Tracking Device (HWTD) test results and analysis. The second part of this study focused on developing accelerated mix testing models to considerably reduce test duration. To accomplish the first objective, nine fine-graded Superpave mixes of 12.5-mm nominal maximum aggregate size (NMAS) with asphalt grade PG 64-22 from six administrative districts of KDOT were selected. Specimens were prepared at three different target air void levels @ N[subscript]design gyrations and four target simulated in-place density levels with the Superpave gyratory compactor. Average number of wheel passes to 20-mm rut depth, creep slope, stripping slope, and stripping inflection point in HWTD tests were recorded and then used in the statistical analysis. Results showed that, in general, higher simulated in-place density up to a certain limit of 91% to 93%, results in a higher number of wheel passes until 20-mm rut depth in HWTD tests. A Superpave mixture with very low air voids @ N[subscript]design (2%) level performed very poorly in the HWTD test. HWTD tests were also performed on six 12.5-mm NMAS mixtures with air voids @ N[subscript]design of 4% for six projects, simulated in-place density of 93%, two temperature levels and five load levels with binder grades of PG 64-22, PG 64-28, and PG 70-22. Field cores of 150-mm in diameter from three projects in three KDOT districts with 12.5-mm NMAS and asphalt grade of PG 64-22 were also obtained and tested in HWTD for model evaluation. HWTD test results indicated as expected. Statistical analysis was performed and accelerated mix testing models were developed to determine the effect of increased temperature and load on the duration of the HWTD test. Good consistency between predicted and observed test results was obtained when higher temperature and standard load level were used. Test duration of the HWTD can thus be reduced to two hours or less using accelerated mix testing (statistical) models.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: A study was conducted between 2000 and 2002 in the lower Berg River catchment of the semi-arid Western Cape Province to investigate the effect of irrigation developments (wheat fields to table grapes) on the quality of the Berg River as well as the sustainability of these developments. This study was necessitated by the mineralisation of both the Breede and Berg River, probably due to irrigation together with the higher pressure on these water resources from the growing demand for fresh water from the Cape Town metropolitan area. Water and Salt balances of two dominant soil patterns (Glenrosa/Swartland and Oakleaf/Hutton soil forms) from the catchment area were monitored at two localities. Vineyard blocks of different ages in the same soil forms were used to study the effect of irrigation over time. The electrical conductivity of the soil water extracts (ECe) was measured three times over depth at the selected sites and the quality of irrigation and drainage return-flow were monitored. Soil water storing capacities of these stony (high rough fragment' fractions) soils were also characterised for more efficient drainage quantity prediction. Glenrosa/Swartland soils showed the highest ECe's (200-400 mx.m") that decreased significantly after four to five years of irrigation and distribution became more uniform over depth. These high salt concentrations were explained due to natural occurrence of salts, mineral weathering and salts from the irrigation water. Oakleaf/Hutton soils showed lower ECe's « 200 nfS.m") but they are subject to the quality of the irrigation water, which is not that constant over years. Localised salt accumulation was observed due to the irrigation method and became more prominent over years. Drainage quantities were under predicted because of the big/high rough fragment fractions and the occurrence of preferential-flow. This prohibited the accurate calculation of the soil water house holding characteristics. It also led to the under calculation of salt return-flow, but it was very evident that the most salt retumflow occurred from the Glenrosa/Swartland soils. Effective irrigation management to achieve and maintain optimal soil water levels and to reduce the negative impact of high ECe's is essential for the sustainability of these irrigation developments. At present it does not seem that the irrigation return-flow is causing dramatic mineralisation of the lower Berg River, but it is a situation that must be monitored as the developments extent and become older (come into production). It seems that irrigation return-flow only has an influence on the quality of the river at the beginning of such a development, but after about three years the influence directly correlates with the quality of irrigation water and mineral weathering. / AFRIKAANSE OPSOMMING: 'n Studie is gedurende die jare 2000 tot 2002 in die benede Bergrivier opvanggebied van die semi-ariede Wes-Kaap Provinsie gedoen om die effek van besproeiingsontwikkelings (koringlande na tafeldruiwe) op die kwaliteit van die Bergrivier se water, asook die volhoubaarheid van besproeiingslandbou te ondersoek. Hierdie studie was genoodsaak deur toenemende versouting van beide die Breede- en Bergrivier, waarskynlik a.g.v. besproeiing, tesarne met groter druk op hierdie waterbronne van wee die groeiende aanvraag na vars water deur die Kaapstadse metropool. Water- en soutbalanse van twee dominante grondpatrone (Glenrosa/Swartland en Oakleaf/Hutton grondvorms) binne die opvanggebied was by twee lokaliteite gemoniteer. Wingerdblokke van verskillende ouderdomme binne dieselfde grondvorms is gebruik om die effek van besproeiing oor tyd te ondersoek. Die elektriese geleiding van die grondwaterekstrak (EGe) was drie maal op verskillende dieptes by geselekteerde persele gemeet en die kwaliteit van besproeiingswater en dreineringsterugvloei was deurgaans gemoniteer. Grondwaterstoringskapasiteite van hierdie klipryke ( hoe 'growwe fragment fraksie) gronde was ook gekarakteriseer vir meer doeltreffende voorspellings van dreineringshoeveelhede. Glenrosa/Swartland gronde het die hoogste EGe's getoon (200-400 mx.m') wat na vier tot vyf jaar se besproeiing aansienlik afgeneem het en meer uniform met diepte versprei was. Die hoe soutkonsentrasies is veroorsaak deur die natuurlike voorkoms van sout in die grond, minerale verwering en sout vanuit die besproeiingswater. Oakleaf/Hutton gronde het laer EGe's getoon « 200 mS.m-I ), maar hierdie gronde se soutinhoud is ook onderhewig aan die kwaliteit van die besproeiingswater en dreinering wat oor jare nie baie konstant was en nog is nie. Gelokaliseerde soutaansarneling tussen wingerdrye is ook waargeneem a.g.v. die besproeiingsmetode en dit word meer prominent oor jare. Dreineringshoeveelhede was onder-voorspel a.g.v. die groot/hoe growwe fragment fraksies en voorkoms van voorkeurvloei, wat die akkurate modellering van grondwaterhuishouding beperk het. Dit het ook daartoe gelei dat soutterugvloei ondervoorspel was, maar dit was duidelik dat die meeste soutterugvloei vanuit die Glenrosa/Swartland gronde plaasvind. Effektiewe besproeiingsbestuur, om optimale grondwaterpeile te handhaaf en om negatiewe effekte van hoe EGe te beperk, is noodsaaklik vir die volhoubaarheid van hierdie tipe besproeiingsontwikkelings. Tans blyk dit nie of besproeiingsterugvloei drarnatiese versouting van die benede Bergrivier veroorsaak nie, maar dit is egter 'n situasie wat deeglik gemoniteer moet word soos wat ontwikkelings uitbrei en ouer word (in produksie kom). Besproeiingsterugvloei het dus net aan die begin van so 'n ontwikkelling 'n invloed op die EG van die rivier, maar na ongeveer drie jaar hou die invloed direk verband met die kwaliteit van die besproeiingswater en minerale verwenng.