Basal melting of ice shelves is causing accelerating mass loss from the Antarctic Ice Sheet, yet the oceanographic processes which drive this are rarely observed. This thesis uses new observations from phase sensitive radar and moored oceanographic instruments to describe the processes which drive rapid basal melting of the north-western Ross Ice Shelf. Oceanographic conditions at the mooring site are strongly influenced by the neighbouring Ross Sea Polynya. High Salinity Shelf Water fills the lower water column continuously, but during summer a southward flow ventilates the cavity bringing Antarctic Surface Water (AASW) to the site. Tides account for half of the flow speed variance, and low frequency variability is influenced by local winds, and eddies associated with sea ice production in the polynya. Four years of basal melt rate observations show a mean melt rate of 1.8 m y$^{-1}$ at the mooring site and a strong seasonal cycle driven principally by water temperature variations. Radar observations show that melt rates vary rapidly and continuously in response to flow speed variability, and rapid melting occurs only when flow speeds are high. Radar observations of melt rates from 78 sites on the Ross and McMurdo ice shelves show an area-averaged annual-mean basal melt rate of 1.35 m y$^{-1}$, implying a net basal mass loss of 9.6 Gt y$^{-1}$ from the region. Melt rates are highest near the ice front where annual-mean and short-term summer rates reached 7.7 m y$^{-1}$ and 53 m y$^{-1}$, respectively. The seasonal and spatial variations in melt rate are consistent with melting driven by the summer inflow of AASW. Observations of boundary layer water temperature, flow speed and melt rates indicate that melt rates scale linearly with current speed, but sub-linearly with temperature in the outer boundary layer, possibly due to the stabilising effects of melt water input. Existing melt rate parameterisations which account for flow speed can be tuned to match the observations when thermal driving is low, but overestimate melt rates at higher temperatures, implying the need for further refinements to the models.

Orientador: Salvador Massaguer Roig / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-05T11:20:00Z (GMT). No. of bitstreams: 1 Busani_SilviaFatimaBorges_D.PDF: 12953590 bytes, checksum: f4928b1a7cba5073da7384ea057dda79 (MD5) Previous issue date: 2005 / Doutorado / Doutor em Tecnologia de Alimentos

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The interaction of numerous sedimentary processes at key transition points along the depositional profile results in a complex heterogeneity in ancient basin margin successions. This complexity is generally well studied along depositional dip sections, but lateral (strike) variability and consequent implications for sediment distribution and stratigraphic architecture is commonly less well constrained. In the Karoo Basin, continuous NW-SE-oriented exposure over 80 km has been characterized by 53 logs with 9910 m of cumulative thickness, >2500 palaeocurrent measurements, and ground-, drone- and helicopter-based photo panels. Palaeoflow indicators suggest dominant sediment transport was to the N-NE, with E-W and NE-SW bidirectional components. These are consistent with a strike orientation of the outcrop belt relative to the NE-N margin progradation direction and a NE-SW reworking by waves orientation. In the south of the study area, upper slope and shelf edge parasequences (50-75 m-thick), show current ripples and inverse-to-normal grading in micaceous and organic-rich siltstones and sandstones. They are interpreted as river-dominated prodelta and mouth bar deposits, locally incised by distributary channels (100 m-thick, 1.5 km-wide). Overlying shelf parasequences are thinner (15-50 m) with symmetrical ripple tops, HCS and low angle cross bedding, interpreted as wave-influenced deltaic or shoreface deposits. They transition upward into erosive-based, fining-up sandstones and isolated sharp-based tabular climbing-rippled sandstones, interpreted as channels and crevasse splays within delta plain mudstones. Along strike to the north, upper slope parasequences show more wave reworking indicators and no evidence of gullying or incision. Overlying shelf parasequences are sandier, more amalgamated and strongly influenced by wave action. They are interpreted as offshore, shoreface, foreshore and strandplain deposits. Southern nearshore environments were therefore more river-dominated with bypass and sediment delivery to deeper parts of the basin across a steep, more erosive margin. Wave and storm current redistribution along strike to the northern, lower gradient margin resulted in higher net-to-gross and sand connectivity on a wider shelf, without major incision, bypass and sand supply to the upper slope. No evidence of major avulsions in the upstream tributary and distributary systems are interpreted because the bypass and fluvial-dominated characteristics are persistent in the southern areas through time, whereas the northern margin maintained a sand-starved upper slope and a wave dominated shelf succession. The overall thicker and delta- dominated succession in the south, and the thinner, more condensed and wave dominated stratigraphy in the north are interpreted to be controlled by a combination of basement and basin configuration and differential basin margin physiography. However, relative sea level fluctuations controlled the stacking patterns, with an overall shallowing-upward profile that can be subdivided into two prograding phases, separated by a transgressive phase. At parasequence scale, climate, autocyclicity and coastal processes influenced the equilibrium between sediment input, redistribution and compensational stacking. This study demonstrates that although basin margin successions may be consistently progradational, the interaction of mixed coastal processes and differential spatial configuration can result in a complex along-strike sedimentary architecture, with major implications for sediment distribution through time and space.

Commonly referred to as “red tide”, harmful algal blooms (HABs) formed by Karenia brevis occur frequently in the Gulf of Mexico (GOM). A bloom is defined as cell abundances >105 cells L-1. This thesis will focus primarily on Karenia brevis, formerly known as Gymnodinium breve, in the Gulf of Mexico. K. brevis is harmful because it produces brevetoxin, a ladder-frame polyether that acts as a potent neurotoxin in vertebrates. K. brevis commonly causes fish kills, respiratory irritation in humans, and Neurotoxic Shellfish Poisoning (NSP) if ingested. Blooms of K. brevis occur almost annually along the West Florida Shelf (WFS) in the late summer and early fall, when the coastal current is favorable for bloom initiation. Along the Texas-Louisiana shelf (TLS) however, blooms of K. brevis are infrequent and sporadic. While much is known of the blooms along the WFS due to their frequent presence, little is known of the mechanisms driving the blooms along the TLS due to their inconsistent presence. To understand the stochastic nature of HABs along the TLS, historical data of bloom occurrences from 1996 to present were compared with NOAA station PTAT2 wind, sea-level pressure, air and water temperature data and NCEP NARR-A sea-level pressure data. The difference in the monthly-mean along-shore component of the wind was statistically significant between bloom and non-bloom years in September (p<<0.001) and April (p=0.0015), with bloom years having a strong downcoast current. Monthly mean water temperature values yielded similar results between bloom and non-bloom years. Both March and September monthly-mean water temperature values were lower during non-bloom years with p-values of 0.01 and 0.048, respectively. These results suggest the possibly of forecasting for HABs along the TLS with currently measured, publicly available data.

<p>Temperature is the common accelerant that is used for shelf-life determination of shelf-stable food because it is easy to use and there are models such as Q₁₀and Arrhenius, which are available for shelf-life prediction. The accelerated shelf-life test (ASLT) still requires months of analysis time as it only uses temperature as the accelerant. Oxygen pressure as an accelerant has not been given much attention even though many studies have shown the negative impact of oxygen on the shelf-life of food. An effective analysis method with multiple accelerants has the potential for the development of a rapid shelf-life determination method. Hence, this research focused on the invention of a rapid method, named the Ultra-Accelerated Shelf-Life Test (UASLT) that combines oxygen pressure and temperature as accelerants and the development of shelf-life prediction model(s). The study hypothesized that the application of elevated oxygen pressure and elevated temperature (40C) increases the amount of oxygen diffusing into packaged food which leads to rapid degradation of nutrients that further reduces the overall shelf-life analysis time compared to the ASLT method. A custom-made high-pressure chamber with a 100% oxygen environment at 40C was designed and developed as part of the UASLT method. The impact of the application of oxygen pressure on oxygen diffusivity in polymeric food packaging materials was investigated on three packages with different oxygen permeability properties. The application of oxygen pressure significantly increased the rate of oxygen transfer and the oxygen diffusivity values for all packaging materials compared to the counterparts that were not exposed to the pressure. A shelf-stable model food fortified with vitamins A, B1, C and D3 was developed to investigate the effectiveness of the UASLT method in degrading the quality indicators in the model foods in a polyethylene terephthalate (PET) container. PET was chosen as it was the most permeable to oxygen. Model food was also subjected to ASLT conditions at the same temperature without additional pressure and at room temperature (control). A degradation of 27.1 ± 1.9%, 13.9± 2.1%, 35.8 ± 1.0%, and 35.4 ± 0.7% were seen in vitamins A, B1, C and D3, respectively, in just 50 days. Slower degradation was observed with samples kept under the ASLT conditions for 105 days and reached a degradation of 24.0 ± 2.0%, 4.9 ± 6.1%, 32.0 ± 3.1% and 25.1 ± 1.5% for vitamin A, B1, C and D3, respectively. The control samples that were studied for 210 days showed 14.9 ± 5.0%, 2.0 ± 2.2%, 13.8 ± 2.2% and 10.6% ± 0.8% degradation in vitamins A, B1, C and D3, respectively. The increase in the dE values due to browning in samples kept at the UASLT, ASLT and control conditions were 11.67 ± 0.09, 7.49 ± 0.19 and 2.51 ± 0.11, respectively. The degradation of vitamins A, C, D3 was analyzed using the 1st order kinetic and the rate constant,    (day^-1) was used to develop four prediction models. Vitamin B1 values were omitted from the kinetic analysis due to insufficient degradation. Two temperature-oxygen diffusion models were developed by correlating oxygen diffusivity and   . Comparisons were made with the temperature-based models of    and Arrhenius. The predicted    values across the models were in the range of 0.051-0.054 day^-1,0.080-0.088 day^-1 and 0.048-0.051 day^-1, for vitamin A, C and D3, respectively. The    values estimated for vitamins A, C, and D3 were 2.16, 2.63 and 2.62, respectively. The predicted shelf-life of vitamin A, C and D3 to undergo 25% reduction was in the range of 404 to 551, 321-353 and 529-583 days across all models, respectively. The shelf-life predicted from the temperature-oxygen diffusion models was close to the temperature models indicating the potential to be paired with the UASLT method. Experimental verification is needed to analyze the errors in the prediction. The addition of oxygen pressure further reduced the shelf-life analysis time by 50% compared to ASLT. Elevated external oxygen pressure can be used as an accelerant along with elevated temperatures (40C) for rapid shelf-life testing of packaged foods. This novel approach has potential application in the food industry for faster shelf-life analysis of food.</p>

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The space shuttle has been flying for seventeen years and NASA plans to fly it for many more. To meet the requirement of supporting future flights, NASA has undertaken a Shuttle Upgrades Program to improve various shuttle components. The avionics on the solid rocket booster (SRB) is one of the areas being upgraded. To develop avionics hardware, the environments that they are to encounter during flight must be defined to a higher degree of fidelity than is currently available. This paper describes the effort to determine these environments via the use of a commercial off the shelf data acquisition system.

International Telemetering Conference Proceedings / October 28-31, 1996 / Town and Country Hotel and Convention Center, San Diego, California / We have long used standards to guide the development process of software systems. Standards such as POSIX, X-Windows, SQL have become part of the language of software developers and have guided the coding of systems that are intended to be portable and interoperable. Standards also have a role to play in the integration of commercial off-the-shelf (COTS) products. At NASA's Goddard Space Flight Center, we have been participating on the Renaissance Team, a reengineering effort that has seen the focus shift from custom-built systems to the use of COTS to satisfy prime mission functions. As part of this effort, we developed a process that identified standards that are applicable to the evaluation and integration of products and assessed how those standards should be applied. Since the goal is to develop a set of standards that can be used to instantiate systems of differing sizes and capabilities, the standards selected have been broken into four areas: global integration standards, global development standards, mission development standards, and mission integration standards. Each of the areas is less restrictive than the preceding area in the standards that are allowed. This paper describes the process that we used to select and categorize the standards to be applied to Renaissance systems.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Grape quality is important for the producer, exporter and the consumer. Consumers judge table grapes according to their size, colour, taste and shelf life. The consumer’s prerequisites will influence the producer. Therefore, it is essential to know how the table grape berry develops so that it can be manipulated, favouring the postharvest quality and shelf life. This study was performed on Prime and Crimson Seedless, both grafted onto Ramsey, in the Paarl district of South Africa. The aim of this study was to describe and quantify table grape berry development and compositional changes taking place throughout growth and ripening. The effect of sugar:acid ratio on postharvest shelf life was also evaluated. To evaluate whether berry size influenced the measured development parameters, three berry sizes were induced for both cultivars by using plant bioregulators such as gibberellic acid (GA3) and forchlorfenuron – synthetic cytokinin (CPPU) or girdling. The following sizes were obtained for Prime: (i) small berries (<20 mm) with no treatment, which acted as the control; (ii) medium berries (20-24 mm) obtained by 15 ppm GA3 application at 8 mm berry size; (iii) large berries (>24 mm) obtained by combination of 15 ppm GA3 and 1 ppm CPPU application at 8 mm berry size. Crimson Seedless berry sizes were as follows: (i) small berries (<18 mm) with no treatment, which acted as the control; (ii) medium berries (18-22 mm) treated with 10 ppm GA3 at 7 mm berry size; (iii) large berries (>22 mm) treated with 10 ppm GA3 and vines were girdled at 7 mm berry size. To evaluate the effect of sugar:acid ratio on postharvest shelf life, grapes were stored for five weeks at -0.5 ˚C and another week at 7.5˚C. The bunches were evaluated for loose berries, browning, soft tissue breakdown, decay and berry split. The following components were analysed for both cultivars to determine changes in berry composition throughout the season: berry fresh weight, total soluble solids (TSS), glucose, fructose, titratable acidity (TA), tartaric acid, malic acid, abscisic acid (ABA) and total phenols. Total and individual anthocyanins were analysed for Crimson Seedless. Differences were obtained for the three berry sizes for both cultivars. Véraison, representing the start of ripening, started at the same time in successive seasons: 21 days after pea size berry (5 mm berry diameter) for Prime and 28 days after pea size berry (5 mm berry diameter) for Crimson Seedless. A lag stage was not observed, at seven day sampling intervals, for either of the cultivars. Components such as TSS, glucose, fructose and TA content per berry were influenced by berry size in either one or in both seasons for both cultivars. Significant changes in component concentration were detected at the start of, or around véraison. Sugar concentrations (TSS) already started to increase for both cultivars before the start of véraison. At véraison, concentrations of glucose, fructose and ABA increased while concentrations of TA, tartaric acid, malic acid and total phenols decreased. Total anthocyanins in Crimson Seedless started to increase one week after véraison commenced. The main anthocyanin found in Crimson Seedless was peonidin-3-glucoside. During ripening a 1:1 glucose:fructose ratio was detected in both cultivars. Prime tartaric:malic acid ratio was lower than Crimson Seedless tartaric:malic acid ratio in both seasons. Tartaric acid was the main organic acid found in Prime, while malic acid was the main organic acid found in Crimson Seedless. No significant differences were found in the postharvest defects between the different berry sizes. However, tendencies for differences were observed which led to the assumption that medium size berries were more prone to loose berries in both cultivars. Large berries showed a higher percentage berry split for both cultivars. Crimson Seedless second harvest date took place 24 hours after rainfall which could have very likely led to the higher percentages berry defects compared to the first season. Greater berry decay was found with later harvest dates for both cultivars. No significant differences were found for the TSS:TA ratio between the three berry sizes for both cultivars. Postharvest defects were therefore found not only to be influenced by TSS:TA ratio but rather by harvest date and packing procedures. Environmental conditions prior to harvest also had an impact on postharvest shelf life. / AFRIKAANSE OPSOMMING: Druif kwaliteit is belangrik vir die produsent, uitvoerder en verbruiker. Tafeldruiwe word gekeur deur die verbruiker volgens grootte, kleur, smaak en raklewe. Die verbruiker se voorkeure sal dus die produsent beïnvloed. Daarom is dit belangrik om te weet hoe tafeldruiwe ontwikkel ten einde korrelsamestelling te manipuleer om na-oes kwaliteit en raklewe te kan bevoordeel. Hierdie studie is uitgevoer op Prime en Crimson Seedless, beide geënt op Ramsey, in die Paarl distrik van Suid Afrika. Die doel van die studie is om vas te stel hoe korrelsamestelling gedurende groei en rypwording verander. Die effek van suiker:suurverhouding op na-oes raklewe is ook geëvalueer. Om te kan meet of korrel grootte die gemete parameter beïnvloed is drie korrelgroottes verkry vir albei kultivars deur die gebruik van plant bioreguleerders, te wete gibbereliensuur (GA3) en sintetiese sitokiniene (CPPU), of ringelering. Die volgende korrelgroottes is verkry vir Prime: (i) klein korrels (<20 mm) d.m.v. geen behandeling, geklassifiseerd as kontrole; (ii) medium korrels (20-24 mm) d.m.v. ‘n 15 dpm GA3 behandeling by 8 mm korrelgrootte; (iii) groot korrels (>24 mm) d.m.v. ‘n kombinasie van 15 dpm GA3 en 1 dpm CPPU by 8 mm korrelgrootte. Crimson Seedless korrelgroottes was soos volg: (i) klein korrels (<18 mm) d.m.v. geen behandeling, wat as kontrole gedien het; (ii) medium korrels (18-22 mm) d.m.v. ‘n 10 dpm GA3 behandeling by 7 mm korrelgrootte; (iii) groot korrels (>22 mm) d.m.v. ‘n 10 dpm GA3 behandeling en gelyktydige ringelering by 7 mm korrelgrootte. Om die effek van suiker:suur verhouding op na-oes houvermoë te kon evalueer was druiwe gestoor vir vyf weke by -0.5˚C en ‘n verdere week by 7˚C. Die trosse is geëvalueer vir loskorrels, verbruining, sagte weefsel afbreek, verval en korrelbars. Die volgende komponente is geanaliseer vir albei kultivars om veranderinge in korrelsamestelling gedurende die seisoen te bepaal: vars korrelgewig, totale oplosbare vaste stowwe (suikerinhoud), glukose, fruktose, titreerbare sure, wynsteensuur, appelsuur, absisiensuur en totale fenole. Die totale en individuele antosianiene is ook vir Crimson Seedless gemeet. Beduidende verskille tussen die drie korrelgroottes vir albei kultivars is verkry. Deurslaan, naamlik die begin van rypwording, het op dieselfde dag in opeenvolgende seisoene plaasgevind: 21 dae na ertjiekorrel grootte (5 mm korrel deursnee) vir Prime en 28 dae na ertjiekorrel grootte (5 mm korrel deursnee) vir Crimson Seedless. In teenstelling met die tipiese korrel ontwikkelingspatroon is ‘n rusfase nie waargeneem by beide kultivars nie. Komponente soos suikerinhoud, glukose, fruktose en titreerbare suur inhoud per korrel is deur korrelgrootte beïnvloed in een of albei seisoene vir beide kultivars. Suiker konsentrasie van albei kultivars het reeds voor deurslaan begin toeneem. By deurslaan het die konsentrasies van glukose, fruktose en absisiensuur inhoud toegeneem, terwyl die konsentraies van titreerbare sure, wynsteensuur, appelsuur en totale fenole gedaal het. Totale antosianiene in Crimson Seedless het ‘n week na deurslaan begin toeneem. Die hoof antosianien in Crimson Seedless is peonidien-3-glukosied. Gedurende rypwording was daar ‘n 1:1 glukose:fruktose verhouding gevind vir beide kultivars. In terme van sure is Prime se wynsteensuur:appelsuur verhouding laer as in Crimson Seedless vir albei seisoene. Wynsteensuur is die hoof organiese suur in Prime terwyl appelsuur die hoof organiese suur in Crimson Seedless is. Geen betekenisvolle verskille vir na-oes houvermoë tussen korrelgroottes is waargeneem vir beide kultivars nie. Daar was egter tendense wat aanleiding gegee het in die aanname dat medium grootte korrels geneig is tot loskorrels in albei kultivars. Groot korrels het ‘n hoër korrelbars persentasie getoon vir beide kultivars. Crimson Seedless se tweede oes het plaasgevind 24 uur na reënval, wat aanleiding gegee het tot hoër persentasies korrelbederf. Hoër persentasie korrelbederf was ook gevind met later oesdatums. Geen beduidende verskille is gevind vir suiker:suur verhouding tussen die drie korrelgroottes vir beide kultivars nie. Dus word na-oes houvermoë nie net deur suiker:suur verhouding beïnvloed nie, maar ook deur oestyd en verpakkingsprodsedures. Omgewingsomstandighede voor oes kan ook na-oes houvermoë beïnvloed.