Antarctic ice sheet topography, cavity geometry, and global bathymetry (RTopo 1.0.5-beta)

Sub-ice shelf circulation and freezing/melting rates in ocean general circulation models depend critically on an accurate and consistent representation of cavity geometry. Existing global or pan-Antarctic data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional fields into a global data set. We use the S-2004 global 1-minute bathymetry as the backbone and add an improved version of the BEDMAP topography for an area that roughly coincides with the Antarctic continental shelf. Locations of the merging line have been carefully adjusted in order to get the best out of each data set. High-resolution gridded data for upper and lower ice surface topography and cavity geometry of the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves, and for Pine Island Glacier have been carefully merged into the ambient ice and ocean topographies. Multibeam survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI), British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO), gridded, and again carefully merged into the existing bathymetry map. The global 1-minute dataset (RTopo-1 Version 1.0.5) has been split into two netCDF files. The first contains digital maps for global bedrock topography, ice bottom topography, and surface elevation. The second contains the auxiliary maps for data sources and the surface type mask. A regional subset that covers all variables for the region south of 50 deg S is also available in netCDF format. Datasets for the locations of grounding and coast lines are provided in ASCII format.

Heat fluxes and surface radiation measurements from Samoylov Island, Lena Delta, Siberia, October 2007 to March 2008

In this study, we present the winter time surface energy balance at a polygonal tundra site in northern Siberia based on independent measurements of the net radiation, the sensible heat flux and the ground heat flux from two winter seasons. The latent heat flux is inferred from measurements of the atmospheric turbulence characteristics and a model approach. The long-wave radiation is found to be the dominant factor in the surface energy balance. The radiative losses are balanced to about 60 % by the ground heat flux and almost 40 % by the sensible heat fluxes, whereas the contribution of the latent heat flux is small. The main controlling factors of the surface energy budget are the snow cover, the cloudiness and the soil temperature gradient. Large spatial differences in the surface energy balance are observed between tundra soils and a small pond. The ground heat flux released at a freezing pond is by a factor of two higher compared to the freezing soil, whereas large differences in net radiation between the pond and soil are only observed at the end of the winter period. Differences in the surface energy balance between the two winter seasons are found to be related to differences in snow depth and cloud cover which strongly affect the temperature evolution and the freeze-up at the investigated pond.

Short Communication Over-Winter Channel Bed Temperature Regimes Generated by Contrasting Snow Accumulation in a High Arctic River

We report experimental results of near-surface winter temperatures along and adjacent to the channel bed of a High Arctic river on Melville Island, Canada. Temperature loggers 5cm below the ground surface in areas where the terrain suggests varying snow accumulation patterns revealed that the maximum winter difference between air and near-surface temperatures ranged from 0 to +30°C during the winter of 2012–13, and that shallow near-surface freezing conditions were delayed for up to 21 days in some locations. Cooling to -10°C was delayed for up to 117 days. Modelled temperature at the top of permafrost indicates that permafrost at locations with thick snow can be up to 8°C warmer than those with thin snow. This thermal evidence for an ameliorated surface environment indicates the potential for substantial extended microbial and biogeochemical cycling during early winter. Rapid thaw of the bed during initiation of snowmelt in spring also indicates a high degree of hydrological connectivity. Therefore, snow-filled channels may contribute to biogeochemical and aquatic cycling in High Arctic rivers.

Exploring several nonconventional interactions of ice-binding proteins

Traditionally, ice-binding proteins (IBPs), also known as antifreeze proteins (AFPs), have been defined by two universal activities: ice recrystallization inhibition and thermal hysteresis. However, there remains the possibility IBPs have other complementary functions given the diversity found within this protein group. This thesis explores some of these in both natural and applied settings, in the hopes of furthering our understanding of this remarkable group of proteins. Plant IBPs could function as part of a defensive strategy against ice nucleators produced by certain pathogens. To assess this hypothesis, recombinant IBPs from perennial ryegrass and purple false brome were combined with the ice nucleation protein (INP) from the plant pathogen, Pseudomonas syringae. Strikingly, the plant proteins depressed the freezing point of the bacterial INP, while a fish AFP could not, nor did the INPs have any effect on IBP activity. Thus, the interaction between these two different proteins suggests a role in plant defensive strategies against pathogenic bacteria as another IBP function. In addition, the potential use of hyperactive insect IBPs in organ preservation was investigated. Current kidney preservation techniques involve storing the organ at 4 °C for a maximum of 24 h prior to transplantation. Extending this “safe” time would have profound effects on renal transplants, however, ischemic injury is prevalent when storage periods are prolonged. Experiments described here allowed subzero preservation for 72 h with the addition of a beetle IBP to CryoStasis® solution. Kidneys stored using the traditional technique for 24 h and the method developed here for 72 h showed similar levels of biomarker enzymes, underscoring the potential utility of insect IBPs for future transplant purposes. Finally, IBP function in the freeze-tolerant gall fly, Eurosta solidaginis, was examined. Larvae representing the mid-autumn stage displayed ice-binding activity, suggesting an IBP is being expressed, possibly as a protective measure against freezing damage when fall temperatures can unpredictably drop. IBP activity was also observed in the larvae’s host plant, Solidago spp. Mass spectrometry analysis of ice-affinity purified plant extracts provided three candidate pathogenesis-related proteins that could be responsible for the detected activity, further demonstrating additional functions of IBPs.

Ecophysiology of Adonis distorta, a high-mountain species endemic of the Central Apennines

Morphological, anatomical and physiological plant and leaf traits of A. distorta, an endemic species of the Central Apennines on the Majella Massif, growing at 2,675 m a.s.l, were analyzed. The length of the phenological cycle starts immediately after the snowmelt at the end of May, lasting 128 ± 10 days. The low A. distorta height  (Hmax= 64 ± 4 mm) and total leaf area (TLA= 38 ± 9 cm2) associated to a high leaf mass area (LMA =11.8±0.6 mg cm−2) and a relatively high leaf tissue density (LTD = 124.6±14.3 mg cm−3) seem to be adaptive traits to the stress factors of the environment where it grows. From a physiological point of view, the high A. distorta photosynthetic rates (PN =19.6 ± 2.3 µmol m−2 s−1) and total chlorophyll content (Chla+b = 0.88 ± 0.13 mg g−1) in July are justified by the favorable temperature. PN decreases by 87% in September at the beginning of plant senescence. Photosynthesis and leaf respiration (RD) variations allow A. distorta to maintain a positive carbon balance during the growing season becoming indicative of the efficiency of plant carbon use. The results could be an important tool for conservation programmes of the A. distorta wild populations.

Microscopic Mechanism and Kinetics of Ice Formation at Complex Interfaces: Zooming in on Kaolinite

Most ice in nature forms because of impurities which boost the exceedingly low nucleation rate of pure supercooled water. However, the microscopic details of ice nucleation on these substances remain largely unknown. Here, we have unraveled the molecular mechanism and the kinetics of ice formation on kaolinite, a clay mineral playing a key role in climate science. We find that the formation of ice at strong supercooling in the presence of this clay is about 20 orders of magnitude faster than homogeneous freezing. The critical nucleus is substantially smaller than that found for homogeneous nucleation and, in contrast to the predictions of classical nucleation theory (CNT), it has a strong two-dimensional character. Nonetheless, we show that CNT describes correctly the formation of ice at this complex interface. Kaolinite also promotes the exclusive nucleation of hexagonal ice, as opposed to homogeneous freezing where a mixture of cubic and hexagonal polytypes is observed.

Barriers and facilitators to cooking from 'scratch' using basic or raw ingredients: A qualitative interview study

Background: Previous research has highlighted an ambiguity in understanding cooking related terminology and a number of barriers and facilitators to home meal preparation. However, meals prepared in the home still include convenience products (typically high in sugars, fats and sodium) which can have negative effects on health. Therefore, this study aimed to qualitatively explore: (1) how individuals define cooking from ‘scratch’, and (2) their barriers and facilitators to cooking with basic ingredients.
Methods: 27 semi-structured interviews were conducted with participants (aged 18-58 years) living on the island of Ireland, eliciting definitions of ‘cooking from scratch’ and exploring the reasons participants cook in a particular way. The interviews were professionally transcribed verbatim and Nvivo 10 was used for an inductive thematic analysis.
Results: Our results highlighted that although cooking from ‘scratch’ lacks a single definition, participants viewed it as optimal cooking. Barriers to cooking with raw ingredients included: 1) time pressures; (2) desire to save money; (3) desire for effortless meals; (4) family food preferences; and (5) effect of kitchen disasters. Facilitators included: 1) desire to eat for health and well-being; (2) creative inspiration; (3) ability to plan and prepare meals ahead of time; and (4) greater self-efficacy in one’s cooking ability.
Conclusions: Our findings contribute to understanding how individuals define cooking from ‘scratch’, and barriers and facilitators to cooking with raw ingredients. Interventions should focus on practical sessions to increase cooking self-efficacy; highlight the importance of planning ahead and teach methods such as batch cooking and freezing to facilitate cooking from scratch.

Experimental viscosity measurements of biodiesels at high pressure

The viscosity of biodiesels of soybean and rapeseed biodiesels blended with mineral diesel fuel were measured at pressures of up to 200 MPa. Using a falling sinker-type viscometer reproducible viscosity data were obtained based on the time taken for a sinker to descend a fixed distance down an enclosed tube under the influence of gravity. Measurements were taken using pressures which correspond to those of interest in automotive common rail diesel engines, and at temperatures of between 25oC and 80oC. In all cases, the viscosity of the biodiesel blends were found to increase exponentially for which the blends were noted as being more viscous than pure mineral fuels. A pressure-freezing effect was not observed for the blends.

Guardas prisionais, contextos de atuação e motivações

O contexto prisional tem recebido nos últimos anos uma grande atenção por parte dos investigadores portugueses. Porém, esse estudo não se têm centrado nos guardas prisionais, como grupo profissional. Dada a inexistência de pesquisas sobre esta temática, o presente estudo pretende analisar os contextos em que se desenrola o exercício das funções dos guardas prisionais, uma vez que estas podem produzir desmotivação e desgaste profissional nestes indivíduos. A investigação decorreu com a participação de guardas prisionais, a exercer funções nos Estabelecimentos Prisionais de Chaves, Lamego e Izeda. Para serem atingidos os objetivos propostos, optou-se pelo método qualitativo,através da aplicação de entrevistas semiestruturadas como instrumento de recolha de dados. Durante o mês de Abril e Maio de 2016 foram realizadas entrevistas a quinze guardas prisionais que trabalhavam em contacto direto com os reclusos. Ao longo da análise das entrevistas ficaram patentes nas declarações algumas fontes de desmotivação devido ao congelamento de salários e das progressões na função pública, à inexistência de concursos internos e à ineficácia e injustiça das avaliações de desempenho. Por outro lado, os profissionais estudados afirmam sentir uma fraca valorização das suas funções no serviço, a par de uma má imagem da sua profissão, difundida e sustentada pelos meios de comunicação social. Estes fatores podem contribuir para que eles próprios não se sintam identificados com o grupo profissional ao qual pertencem. Finalmente, os entrevistados manifestam sentir uma falta de formação contínua, cuja existência consideram fundamental.

Factors affecting fertility in frozen-thawed boar sperm

Frozen-thawed boar sperm holds the potential to have an impact on the future of the swine industry. Utilization of this technology could improve a swine producer’s ability to access top-tier genetics from around the world, to improve efficiency, profitability, and the quality of product to meet consumer demands. Effective application of frozen-thawed sperm can help reduce the potential risk associated with devastating economic loss due to the spread of disease. Frozen storage of boar sperm also provides a safeguard in the event of disease outbreaks, as genetic material from paternal lines can be preserved and banked for repopulation purposes. Historically these benefits have been masked by reduction in fertility measures such as litter size. The reduced fertility results from the damage sustained by the sperm cell during cryopreservation. However, increased understanding of this damage has lead to improved cryopreservation methods, ultimately increasing post-thaw viability and fertility. Enhancements in breeding technology have also resulted in a better understanding of the AI methods required to achieve acceptable farrowing rates and litter size. Fertility following AI with frozen-thawed sperm is approaching that of liquid stored sperm, and producers may soon reap the benefits of this technology. This thesis will outline the current swine industry, opportunities for utilizing frozen-thawed sperm, the main components of sperm, why they are susceptible to damage, and current freezing and breeding practices. Objective 1 was to develop a cryopreservation protocol for our lab that resulted in consistent post-thaw motility ( ≥ 40%) that would eventually be used by Illinois boar studs for domestic and international sale of frozen sperm. Evaluation with both manual microscopy and CASA methods were conducted to verify quality. A preliminary breeding trial was then conducted to test the fertility of sperm frozen with this method. There were 41 ejaculates from 23 boars used for freezing. Sperm were frozen at 1.4x109 sperm/mL, averaging 55.61.1% (meanSE) motility, following thaw. The samples assessed were not different (P>0.05) in motility when compared with manual or CASA systems, and results were most reliable at a 1:40 sperm dilution. In the preliminary breeding trial, gilts (n=14) were inseminated with either a single (n=10) or double (n=4) AI using 1, 2, or 4x109 motile, frozen-thawed sperm. Overall, the resulting pregnancy rates averaged 71.4% and numbers of normal fetuses per litter averaged 15.51.3 per litter. A feasibility study for freezing cost per ejaculate was estimated at $275/ejaculate or $11/dose of frozen-thawed semen at standard doses of 5x109 total frozen-thawed sperm. This cost estimate did not include genetic value, fixed equipment costs, depreciation, or variable lab space fees. Objective 2 focused on the proper methods for breeding with frozen-thawed boar sperm to achieve fertility. Our hypothesis was that increased numbers of inseminations and increased numbers of motile frozen-thawed sperm would improve pregnancy rate and litter size. Results showed acceptable fertility at high sperm numbers, but also the optimal method for insemination with the lowest dose tested. Gilts (n=111) responded to synchronization methods and were bred with 1, 2, or 4x109 motile frozen-thawed sperm from six boars using a single AI at 32 h, or a double AI, with the first AI at 24 and 32 h following estrus. Ultrasound was conducted at 12 h intervals to estimate the time of ovulation. On day 32 of gestation, overall pregnancy rate (73%) and number of normal fetuses per litter (10.80.5) across all treatments did not differ, and were not affected by number of motile sperm, or the interaction of number of motile sperm and number of inseminations. However, the number of inseminations tended to affect (P=0.14) the number of normal fetuses. Litter size increased with a double AI compared to single AI. Multiple inseminations helped to allow insemination to occur close to ovulation in response to variation in the time of ovulation. Both pregnancy rate and number of normal fetuses were greater when the time of the AI at 32 h occurred closer to the estimated time of ovulation (P<0.05). In addition, other factors such as presence of an abnormal ovary at day 30 decreased (P<0.001) pregnancy rate, while boar affected number of normal fetuses (P<0.01). Analysis of our data using a fertility index revealed doses of 2x109 motile sperm with multiple AI can achieve acceptable fertility with use of less sperm, when compared to AI using 4x109 motile sperm. The methods described here will investigate the potential for improved fertility when using frozen-thawed sperm, while accounting for variation in time of ovulation.

Otimização da produção biotecnológica de lipases e correlação com a produção de biossurfactantes

As lipases e os biossurfactantes são compostos produzidos por microrganismos através de fermentações em estado sólido (FES) ou sumberso (FSm), os quais são aplicáveis nas indústrias alimentícia e farmacêutica, na bioenergia e na biorremediação, entre outras. O objetivo geral deste trabalho foi otimizar a produção de lipases através de fermentação em estado sólido e fermentação submersa. Os fungos foram selecionados quanto à habilidade de produção de lipases através de FES e FSm e aqueles que apresentaram as maiores atividades lipolíticas foram utilizados na seleção de variáveis significativas e na otimização da produção de lipases nos dois modos de cultivo. Foram empregadas técnicas seqüenciais de planejamento experimental, incluindo planejamentos fracionários, completos e a metodologia de superfície de resposta para a otimização da produção de lipases. As variáveis estudadas na FES foram o pH, o tipo de farelo como fonte de carbono, a fonte de nitrogênio, o indutor, a concentração da fonte de nitrogênio, a concentração do indutor e a cepa do fungo. Na FSm, além das variáveis estudadas na FES, estudaram-se as variáveis concentração inicial de inóculo e agitação. As enzimas produzidas foram caracterizadas quanto à temperatura e pH ótimos e quanto à estabilidade a temperatura e pH. Nas condições otimizadas de produção de lipases, foi avaliada a correlação entre a produção de lipases e bioemulsificantes. Inicialmente foram isolados 28 fungos. Os fungos Aspergillus O- 4 e Aspergillus E-6 foram selecionados como bons produtores de lipases no processo de fermentação em estado sólido e os fungos Penicillium E-3, Trichoderma E-19 e Aspergillus O-8 como bons produtores de lipases através da fermentação submersa. As condições otimizadas para a produção de lipases através de fermentação em estado sólido foram obtidas utilizando-se o fungo Aspergillus O-4, farelo de soja, 2% de nitrato de sódio, 2% de azeite de oliva e pHs inferiores a 5, obtendo-se atividades lipolíticas máximas de 57 U. As condições otimizadas para a produção de lipases na fermentação submersa foram obtidas utilizando-se o fungo Aspergillus O-8, farelo de trigo, 4,5% de extrato de levedura, 2% de óleo de soja e pH 7,15. A máxima atividade obtida durante a etapa de otimização foi 6 U. As lipases obtidas por FES apresentaram atividades máximas a 35ºC e pH 6,0, enquanto que as obtidas por FSm apresentaram ótimos a 37ºC e pH 7,2. A estabilidade térmica das lipases produzidas via FSm foi superior a das lipases obtidas via FES, com atividades residuais de 72% e 26,8% após 1h de exposição a 90ºC e 60ºC, respectivamente. As lipases obtidas via FES foram mais estáveis em pH´s alcalinos, com atividades residuais superiores a 60% após 24 h de exposição, enquanto as lipases produzidas via FSm foram mais estáveis em pH´s ácidos, com 80% de atividade residual na faixa de pH entre 3,5 e 6,5. Na fermentação submersa a correlação entre a produção de lipases e a atividade emulsificante óleo em água (O/A) e água em óleo (A/O) dos extratos foi 95,4% e 86,8%, respectivamente, obtendo-se atividades emulsificantes máximas O/A e A/O de 2,95 UE e 42,7 UE. Embora a maior produção de lipases tenha sido obtida na fermentação em estado sólido, não houve produção concomitante de biossurfactantes. Os extratos da fermentação submersa apresentaram redução da tensão superficial de 50 mN m -1 para 28 mN m -1 e atividade antimicrobiana frente ao microrganismo S. aureus ATCC 25923, com potenciais antimicrobianos de 36 a 43% nos três primeiros dias de fermentação. A fermentação submersa foi a técnica que apresentou os melhores resultados de otimização da produção de lipases, bem como de produção simultânea de biossurfactantes.

Cryopreservation of avocado (Persea Americana Mill.) using somatic embryos

Avocado genetic resources are currently maintained in the form of field repositories at great cost and risk of natural disasters, pest and diseases. Cryopreservation offers a necessary, complimentary method that is safe, cost-effective and long-term. However, long-term maintenance and regeneration of plantlets from avocado somatic embryos has been a major barrier in the development of new avocado cultivars. In this study, two protocols for vitrification-based cryopreservation of avocado somatic embryos were investigated. Globular somatic embryos of two avocado cultivars were tested, revealing cultivar-dependent differences in desiccation tolerance and subsequent freezing resistance, possibly attributed to their size and culture age. A two-step regeneration system, involving an intermediate liquid phase step between subcultures in solid medium, significantly enhanced shoot development from somatic embryo tissue. This work will add considerable value towards cryopreservation of avocado somatic embryos for germplasm conservation and the generation of new and improved avocado cultivars.

Impact of natural and/or chemical stressors on the freeze-tolerant and euryhaline enchytraeid, Enchytraeus albidus

Rapid climatic changes are taking place in Arctic, subarctic and cold temperate regions, where predictions point to an increase in freeze-thaw events, changes in precipitation, evaporation and salinity patterns. Climate change may therefore result in large impacts in ecosystem functioning and dynamics, especially in the presence of contaminants due to intense anthropogenic activities. Even though multiple stress approaches have received increasing interest in the last decades, the number of such studies is limited. In particular, knowledge on the effect of freezethaw events and salinity fluctuations on ecotoxicology of soil invertebrates is lacking, especially important when considering supralittoral species. Therefore, the aim of this thesis was to investigate the effects of low temperature and salinity fluctuations, singly and in combination with contaminants, in the freeze-tolerant and euryhaline enchytraeid Enchytraeus albidus. The assessment of population level endpoints (survival and reproduction), along with physiological and biochemical parameters such as levels of cryoprotectants, ice/water content, oxidative stress biomarkers, cellular energy allocation, and tissue concentration of chemicals (when applied), provided new and valuable knowledge on the effects of selected physical and chemical stressors in E. albidus, and allowed the understanding of adjustments in the primary response mechanisms that enable worms to maintain homeostasis and survival in harsh environments such as polar and temperate-cold regions. The presence of moderate levels of salinity significantly increased freeze-tolerance (mainly evaluated as survival, cryoprotection and ice fraction) and reproduction of E. albidus. Moreover, it contributed to the readjustments of cryoprotectant levels, restoration of antioxidant levels and changed singnificantly the effect and uptake of chemicals (copper cadmium, carbendazim and 4-nonylphenol). Temperature fluctuations (simulated as daily freeze-thaw cycles, between -2ºC and -4ºC) caused substancial negative effect on survival of worms previsouly exposed to non-lethal concentrations of 4-nonylphenol, as compared with constant freezing (-4ºC) and control temperature (2ºC). The decrease in cryoprotectants, increase in energy consumption and the highest concentration of 4-nonylphenol in the tissues have highlighted the high energy requirements and level of toxicity experienced by worms exposed to the combined effect of contaminants and freezing-thawing events. The findings reported on this thesis demonstrate that natural (physical) and chemical stressors, singly or in combination, may alter the dynamics of E. albidus, affecting not only their survival and reproduction (and consequent presence/distribution) but also their physiological and biochemical adaptations. These alterations may lead to severe consequences for the functioning of the ecosystems along the Arctic, subarctic and cold temperate regions, where they play an important role for decomposition of dead organic matter. This thesis provides a scientific basis for improving the setting of safety factors for natural soil ecosystems, and to underline the integration of similar investigations in ecotoxicology, and eventually in risk assessment of contaminants.