Basal crevasses and suture zones in the Larsen C Ice Shelf, Antarctica: Implications for ice shelf stability in a warming climate

Understanding ice shelf structure and processes is paramount to future predictions of sea level rise, as nearly 75% of the ice flux from the Antarctic Ice Sheet (AIS) passes through these gates. The breakup of an ice shelf removes the longitudinal back stress acting on the grounded inland ice and leads to flow acceleration, dynamic thinning and frontal retreat, processes that can be sustained for more than a decade. Increased ice discharge to the ocean contributes to global sea level rise. This dissertation investigates basal crevasses and suture zones, two key structural components of ice shelves, in order to understand how the structure of an ice shelf influences its stability in a warming climate. Ground penetrating radar, high-resolution satellite imagery and a variety of modeling approaches are utilized to assess these features on the Larsen C Ice Shelf but in a manner that considers their influence on ice shelf stability around the AIS. Basal crevasses are largescale (~66% of ice thickness and ten’s of km in length) and abundant features that are significant structural weaknesses. The viscoplastic deformation of the ice shelf in response to the perturbed hydrostatic balance leads to the formation of both surface depressions and crevasses, hence weakening the ice shelf further. Basal crevasses increase the local ice-ocean interface by ~30%, thereby increasing basal roughness and altering ice-ocean interactions. Ice-shelf fractures frequently terminate where they encounter suture zones, regions of material heterogeneity that form at the lateral bounds of meteoric inflows to ice shelves. The termination of a 25 km-long rift in the Churchill Peninsula suture zone is investigated and found to contain ~60 m of accreted marine ice. Steady-state basal melting/freezing rates are determined for the ice shelf and applied to a flowline model to examine the along-flow evolution of ice shelf structure. The thickening surface wedge of locally accumulated meteoric ice, which likely has limited lateral variation in its mechanical properties, accounts for ~60% of the total ice thickness near the calving front. This suggests that the material heterogeneities present in the lower ~40% of the ice column are responsible for resisting fracture propagation and thereby delaying tabular calving events. This represents a highly sensitive aspect of ice-shelf stability, as changes in the oceanic forcing may lead to the loss of this heterogeneity

The spatial distribution of pet dogs and pet cats on the island of Ireland

<p>Abstract</p> <p>Background</p> <p>There is considerable international research regarding the link between human demographics and pet ownership. In several international studies, pet ownership was associated with household demographics including: the presence of children in the household, urban/rural location, level of education and age/family structure. What is lacking across all these studies, however, is an understanding of how these pets are spatially distributed throughout the regions under study. This paper describes the spatial distribution of pet dog and pet cat owning households on the island of Ireland.</p> <p>Results</p> <p>In 2006, there were an estimated 640,620 pet dog owning households and 215,542 pet cat owning households in Ireland. These estimates are derived from logistic regression modelling, based on household composition to determine pet dog ownership and the type of house to determine pet cat ownership. Results are presented using chloropleth maps. There is a higher density of pet dog owning households in the east of Ireland and in the cities than the west of Ireland and rural areas. However, in urban districts there are a lower proportion of households owning pet dogs than in rural districts. There are more households with cats in the urban areas, but the proportion of households with cats is greater in rural areas.</p> <p>Conclusions</p> <p>The difference in spatial distribution of dog ownership is a reflection of a generally higher density of households in the east of Ireland and in major cities. The higher proportion of ownership in the west is understandable given the higher proportion of farmers and rural dwellings in this area. Spatial representation allows us to visualise the impact of human household distribution on the density of both pet dogs and pet cats on the island of Ireland. This information can be used when analysing risk of disease spread, for market research and for instigating veterinary care.</p

Life cycle assessment of geopolymer concrete: A Malaysian context

An electrochemical fuel cell contains first and second monolithic electrically conducting flow field-bipolar plate assemblies arranged essentially parallel to each other such that an inside surface of the first bipolar separator plate is facing an inside surface of the second bipolar separator plate, wherein the bipolar separator plates are electrically and mechanically connected by intervening layers that are directly bonded to each other. The fuel cells can be stacked between endplates and supplied with hydrogen and oxygen to generate electric power. An air cooled condenser for use with a fuel cell stack is composed of a porous foam condensing element and a porous foam cooling element. The condenser can be placed by a fuel cell stack for cooling purposes.U

Study of UV Degradation on Plastic (PET) Aerosols

The present study was aimed to explore the impact of UV radiation, from ‘real world’ environmental exposure, on the degradation of plastic PET aerosol containers. Additionally, the intent was to correlate the ‘real world’ environmental exposure to artificial sunlight, using a Xenon-Arc lamp, to develop a simulated test. The standardized methodology could then be used to evaluate the integrity of the plastic aerosol container and product, without the complexity of using ‘real world’ exposure. Through this study, a lab method was developed and validated that would simulate the effect of UV radiation using the Xenon-Arc. Moreover, a correlation was made for conditions inside the Xenon-Arc chamber that were conducive to testing a plastic pressurized container

Structural or Dispositional? An Experimental Investigation of the Experience of Winning in Social Casino Games (and Impulsivity) on Subsequent Gambling Behaviors

Background and aims: In the present research, we experimentally investigated whether the experience of winning (i.e., inflated payout rates) in a social casino game influenced social casino gamers’ subsequent decision to gamble for money. Furthermore, we assessed whether facets of dispositional impulsivity – negative and positive urgency in particular – also influenced participants’ subsequent gambling. Methods: Social casino gamers who were also current gamblers (N = 318) were asked to play a social casino game to assess their perceptions of the game in exchange for $3. Unbeknownst to them, players were randomly assigned to one of three experimental conditions: winning (n = 110), break-even (n = 103), or losing (n = 105). After playing, participants were offered a chance to gamble their$3 renumeration in an online roulette game. Results: A total of 280 participants (88.1%) elected to gamble, but no between-condition variation in the decision to gamble emerged. Furthermore, there were no differences in gambling on the online roulette between condition. However, higher levels of both negative and positive urgency increased the likelihood of gambling. Finally, impulsivity did not moderate the relationship between experience of winning and decision to gamble. Conclusion: The results suggest that dispositional factors, including impulsive urgency, are implicated in the choice to gamble for social casino gamers following play

Bringing good things to life : New Markets Tax Credits and the opening of low-income communities to investment, including a case study of Pittsfield, Massachusetts

Thesis (S.M. in Real Estate Development)--Massachusetts Institute of Technology, Dept. of Urban Studies and Planning, Center for Real Estate, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (leaves 156-160).The New Markets Tax Credit (NMTC) Program is designed to promote investment and economic growth in urban and rural low-income communities across the country. Created in 2000 as one of the last acts of the Clinton Administration, the NMTC program has allocated $16 billion of tax credits to date to Community Development Entities (CDEs), who in turn use the credits to make investments in target communities. Through the final authorized round of allocations, which is currently projected to be end-of-year 2008, the program will have allocated$19.5 billion in tax credit authority. This thesis investigates how NMTCs work, why they are structured as they are, and who uses them. It reviews the origins as well as the current status of the program, and investigates how one of the most active, innovative CDEs in the country, Massachusetts Housing Investment Corporation (MHIC), uses NMTCs in practice. Finally, this thesis provides a case study of Pittsfield, a small city in western Massachusetts where NMTCs have been used as part of the community's efforts to redevelop the downtown as a cultural and entertainment destination. Pittsfield, once home to a large General Electric manufacturing plant, experienced a rapid economic decline following GE's gradual closure and sale of its operations in the city over the last several decades. This thesis investigates Pittsfield's efforts to redefine itself through a combination of strong leadership, vision, and the effective use of available capital resources such as NMTCs. One of the primary questions raised about NMTCs has involved how to evaluate the impacts of the tax credit investments on their target communities. Especially in an environment in which the re-authorization of the program is not assured, understanding the impacts of NMTC investments is critical if the program is to continue.(cont.) This project lays out an innovative evaluation framework based upon 'theory of change' logic modeling in order to offer a potential guide for NMTC impact evaluation that could be used in practice. In particular, this thesis argues that NMTC investments must be evaluated within the context of broader community redevelopment initiatives and not as stand-alone initiatives. Ultimately, the value of theory of change models both for planning community development initiatives and for evaluating NMTC impacts is demonstrated by constructing such a framework for Pittsfield, Mass.by Daniel J. McGrath.S.M.in Real Estate Developmen

Genes involved in platelet aggregation and activation are downregulated during acute anaphylaxis in humans

Objective: Mechanisms underlying the anaphylactic reaction in humans are not fully understood. Here, we aimed at improving our understanding of anaphylaxis by investigating gene expression changes. Methods: Microarray data set GSE69063 was analysed, describing emergency department (ED) patients with severe anaphylaxis (n = 12), moderate anaphylaxis (n = 6), sepsis (n = 20) and trauma (n = 11). Samples were taken at ED presentation (T0) and 1 h later (T1). Healthy controls were age and sex matched to ED patient groups. Gene expression changes were determined using limma, and pathway analysis applied. Differentially expressed genes were validated in an independent cohort of anaphylaxis patients (n = 31) and matched healthy controls (n = 10), using quantitative reverse transcription-polymerase chain reaction. Results: Platelet aggregation was dysregulated in severe anaphylaxis at T0, but not in moderate anaphylaxis, sepsis or trauma. Dysregulation was not observed in patients who received adrenaline before T0. Seven genes (GATA1 (adjusted P-value = 5.57 × 10−4), TLN1 (adjusted P-value = 9.40 × 10−4), GP1BA (adjusted P-value = 2.15 × 10−2), SELP (adjusted P-value = 2.29 × 10−2), MPL (adjusted P-value = 1.20 × 10−2), F13A1 (adjusted P-value = 1.39 × 10−2) and SPARC (adjusted P-value = 4.06 × 10−2)) were significantly downregulated in severe anaphylaxis patients who did not receive adrenaline before ED arrival, compared with healthy controls. One gene (TLN1 (adjusted P-value = 1.29 × 10−2)) was significantly downregulated in moderate anaphylaxis patients who did not receive adrenaline before ED arrival, compared with healthy controls. Conclusion: Downregulation of genes involved in platelet aggregation and activation is a unique feature of the early anaphylactic reaction not previously reported and may be associated with reaction severity

Digitised audio questionnaire for assessment of informed consent comprehension in a low-literacy African research population: development and psychometric evaluation.

OBJECTIVE: To develop and psychometrically evaluate an audio digitised tool for assessment of comprehension of informed consent among low-literacy Gambian research participants. SETTING: We conducted this study in the Gambia where a high illiteracy rate and absence of standardised writing formats of local languages pose major challenges for research participants to comprehend consent information. We developed a 34-item questionnaire to assess participants' comprehension of key elements of informed consent. The questionnaire was face validated and content validated by experienced researchers. To bypass the challenge of a lack of standardised writing formats, we audiorecorded the questionnaire in three major Gambian languages: Mandinka, Wolof and Fula. The questionnaire was further developed into an audio computer-assisted interview format. PARTICIPANTS: The digitised questionnaire was administered to 250 participants enrolled in two clinical trials in the urban and rural areas of the Gambia. One week after first administration, the questionnaire was readministered to half of the participants who were randomly selected. Participants were eligible if enrolled in the parent trials and could speak any of the three major Gambian languages. OUTCOME MEASURE: The primary outcome measure was reliability and validity of the questionnaire. RESULTS: Item reduction by factor analysis showed that 21 of the question items have strong factor loadings. These were retained along with five other items which were fundamental components of informed consent. The 26-item questionnaire has high internal consistency with a Cronbach's α of 0.73-0.79 and an intraclass correlation coefficient of 0.94 (95% CI 0.923 to 0.954). Hypotheses testing also showed that the questionnaire has a positive correlation with a similar questionnaire and discriminates between participants with and without education. CONCLUSIONS: We have developed a reliable and valid measure of comprehension of informed consent information for the Gambian context, which might be easily adapted to similar settings. This is a major step towards engendering comprehension of informed consent information among low-literacy participants