368 resultados para Cation-exchange Capacity
Resumo:
Putnam's “constrict theory” suggests that ethnic diversity creates challenges for developing and sustaining social capital in urban settings. He argues that diversity decreases social cohesion and reduces social interactions among community residents. While Putnam's thesis is the subject of much debate in North America, the United Kingdom, and Europe, there is a limited focus on how ethnic diversity impacts upon social cohesion and neighborly exchange behaviors in Australia. Employing multilevel modeling and utilizing administrative and survey data from 4,000 residents living in 148 Brisbane suburbs, we assess whether ethnic diversity lowers social cohesion and increases “hunkering.” Our findings indicate that social cohesion and neighborly exchange are attenuated in ethnically diverse suburbs. However, diversity is less consequential for neighborly exchange among immigrants when compared to the general population. Our results provide at least partial support for Putnam's thesis.
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Aromatic radicals form in a variety of reacting gas-phase systems, where their molecular weight growth reactions with unsaturated hydrocarbons are of considerable importance. We have investigated the ion-molecule reaction of the aromatic distonic N-methyl-pyridinium-4-yl (NMP) radical cation with 2-butyne (CH3C CCH3) using ion trap mass spectrometry. Comparison is made to high-level ab initio energy surfaces for the reaction of NMP and for the neutral phenyl radical system. The NMP radical cation reacts rapidly with 2-butyne at ambient temperature, due to the apparent absence of any barrier. The activated vinyl radical adduct predominantly dissociates via loss of a H atom, with lesser amounts of CH3 loss. High-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry allows us to identify small quantities of the collisionally deactivated reaction adduct. Statistical reaction rate theory calculations (master equation/RRKM theory) on the NMP + 2-butyne system support our experimental findings, and indicate a mechanism that predominantly involves an allylic resonance-stabilized radical formed via H atom shuttling between the aromatic ring and the C-4 side-chain, followed by cyclization and/or low-energy H atom beta-scission reactions. A similar mechanism is demonstrated for the neutral phenyl radical (Ph center dot)+2-butyne reaction, forming products that include 3-methylindene. The collisionally deactivated reaction adduct is predicted to be quenched in the form of a resonance-stabilized methylphenylallyl radical. Experiments using a 2,5-dichloro substituted methyl-pyridiniumyl radical cation revealed that in this case CH3 loss from the 2-butyne adduct is favoured over H atom loss, verifying the key role of ortho H atoms, and the shuttling mechanism, in the reactions of aromatic radicals with alkynes. As well as being useful phenyl radical analogues, pyridiniumyl radical cations may form in the ionosphere of Titan, where they could undergo rapid molecular weight growth reactions to yield polycyclic aromatic nitrogen hydrocarbons (PANHs).
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Global pressures of burgeoning population growth and consumption are threatening efforts to reduce negative environmental pressures associated with development such as atmospheric, land and water pollution. For example, the world’s population is now growing at over 70 million per year or 1 billion per decade (Brown, 2007), increasing from 3.5 billion in 1970, to 5 billion in 1990, to 7 billion by 2010 (United Nations, 2002). In 1990 only 13 percent of the global population lived in cities, while in 2007 more than half did. More than 60 percent of the global population lives within 100 kilometers of the coastline (World Resources Institute, 2005) and nearly all of the population growth hereon is forecast to happen in developing countries (Postel, 1999). Future levels of stress on the global environment are therefore likely to increase if current trends are used for forecasting, which is particularly challenging as scientists are already observing significant signs of degradation and failure in environmental systems. For example, the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC, 2007) provided an nequivocal link between climate change and current human activities, in particular: the burning of fossil fuels; deforestation and land clearing; the use of synthetic greenhouse gases; and decomposition of wastes from landfill. The UK Stern Review concluded that within our lifetime there is between a 77 to 99 percent chance (depending on the climate model used) of the global average temperature rising by more than 2 degrees Celsius (Stern, 2006), with a likely greenhouse gas concentration in the atmosphere of 550 parts per million (ppm) or more by around 2100.
Resumo:
This paper reports a study of ion exchange (IX) as an alternative CSG water treatment to the widely used reverse osmosis (RO) desalination process. An IX pilot plant facility has been constructed and operated using both synthetic and real CSG water samples. Application of appropriate synthetic resin technology has proved the effectiveness of IX processes.
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Security models for two-party authenticated key exchange (AKE) protocols have developed over time to provide security even when the adversary learns certain secret keys. In this work, we advance the modelling of AKE protocols by considering more granular, continuous leakage of long-term secrets of protocol participants: the adversary can adaptively request arbitrary leakage of long-term secrets even after the test session is activated, with limits on the amount of leakage per query but no bounds on the total leakage. We present a security model supporting continuous leakage even when the adversary learns certain ephemeral secrets or session keys, and give a generic construction of a two-pass leakage-resilient key exchange protocol that is secure in the model; our protocol achieves continuous, after-the-fact leakage resilience with not much more cost than a previous protocol with only bounded, non-after-the-fact leakage.
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Objectives: To i) identify predictors of admission, and ii) describe outcomes for patients who arrived via ambulance to three Australian public Emergency Departments (EDs), before and after the opening of 41 additional ED beds within the area. Methods: A retrospective, comparative, cohort study using deterministically linked health data collected between 3 September 2006 and 2 September 2008. Data included ambulance offload delay, time to see doctor, ED length of stay (ED LOS), admission requirement, access block, hospital length of stay and in-hospital mortality. Logistic regression analysis was undertaken to identify predictors of hospital admission. Results: One third of all 286,037 ED presentations were via ambulance (n= 79,196) and 40.3% required admission. After increasing emergency capacity, the only outcome measure to improve was in-hospital mortality. Ambulance offload delay, time to see doctor, ED length of stay (ED LOS), admission requirement, access block, hospital length of stay did not improve. Strong predictors of admission before and after increased capacity included: age over 65 years, Australian Triage Scale (ATS) category 1-3, diagnoses of circulatory or respiratory conditions and ED LOS > 4 hours. With additional capacity the odds ratios for these predictors increased for age >65 and ED LOS > 4 hours and decreased for triage category and ED diagnoses. Conclusions: Expanding ED capacity from 81 to 122 beds within a health service area impacted favourably on mortality outcomes but not on time-related service outcomes such as ambulance offload time, time to see doctor and ED LOS. To improve all service outcomes, when altering (increasing/decreasing) ED bed numbers, the whole healthcare system needs to be considered.
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Drawing on principles of social exchange this thesis employs mediated regression to investigate the relationship between internal communication and employee engagement in the Australian workforce. Findings suggest organisations and supervisors should focus internal communication efforts toward building greater perceptions of support and stronger identification among employees in order to foster optimal engagement. This research contributes to public relations and management scholarship through understanding how perceived support and identification act as mediating mechanisms in the relationship between internal communication and employee engagement at the organisational and supervisory level.
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Capacity reduction programmes, in the form of buybacks or decommissioning, have had relatively widespread application in fisheries in the US, Europe and Australia. A common criticism of such programmes is that they remove the least efficient vessels first, resulting in an increase in average efficiency of the remaining fleet, which tends to increase the effective fishing power of the remaining fleet. In this paper, the effects of a buyback programme on average technical efficiency in Australia’s Northern Prawn Fishery are examined using a multi-output production function approach with an explicit inefficiency model. As expected, the results indicate that average efficiency of the remaining vessels was generally greater than that of the removed vessels. Further, there was some evidence of an increase in average scale efficiency in the fleet as the remaining vessels were closer, on average, to the optimal scale. Key factors affecting technical efficiency included company structure and the number of vessels fishing. In regard to fleet size, our model suggests positive externalities associated with more boats fishing at any point in time (due to information sharing and reduced search costs), but also negative externalities due to crowding, with the latter effect dominating the former. Hence, the buyback resulted in a net increase in the individual efficiency of the remaining vessels due to reduced crowding, as well as raising average efficiency through removal of less efficient vessels.
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The buoyancy that the Indian economy experienced between 2000 and 2010, in spite of the global downturn of 2008, is no longer a reality. Growth projections for 2012-13 have been reassessed to 6.5 per cent. This is still higher than most other developed economies of the world (see Figure 1.1), however the growth rate is slowing. The World Bank in its recent forecasts1 expects India’s growth rates not to extend beyond 7.2 % and 7.4 % in the years 2013-14 and 2014-15, respectively. Similarly, the Planning Commission has scaled down the growth target for the 12th Five Year Plan (2012-17) from 9% to 8%. Different reports note different rates, but the consistent message is that the projection of India’s economy is on a downward trend...
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At the 2012 CDIO conference, it was clear to all that engineering for 21st Century challenges and opportunities will be critical to the success of society over the next 2-3 decades, in dealing with pressures including climate change, resource depletion and urban densification. Within this context there is a growing imperative for rapid curriculum renewal towards education for sustainable development across all types and disciplines of engineering education, around the world. Building on a paper presented by these authors at the 2012 CDIO conference, this 2013 roundtable will draw on participants’ experiences to discuss how sustainability knowledge and skills can be embedded within a CDIO-based program using a holistic approach to curriculum renewal. The highly interactive and dynamic session will include two parts: 1) a short presentation from the chairs of the roundtable on an emergent model for rapid curriculum renewal; and 2) a facilitated discussion with participants about challenges and opportunities for action. Session notes will be recorded for distribution among participants following the conference.
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In the avian model of myopia, retinal image degradation quickly leads to ocular enlargement. We now give evidence that regionally specific changes in ocular size are correlated with both biomechanical indices of scleral remodeling, e.g. hydration capacity and with biochemical changes in proteinase activities. The latter include a 72 kDa matrix metalloproteinase (putatively MMP-2), other gelatin-binding MMPs, an acid pH MMP and a serine protease. Specifically, we have found that increases in scleral hydrational capacity parallel increases in collagen degrading activities. Gelatin zymography reveals that eyes with 7 days of retinal image degradation have elevated levels (1.4-fold) of gelatinolytic activities at 72 and 67 kDa M(r) in equatorial and posterior pole regions of the sclera while, after 14 days of treatment, increases are no longer apparent. Lower M(r) zymographic activities at 50, 46 and 37 kDa M(r) are collectively increased in eyes treated for both 7 and 14 days (1.4- and 2.4-fold respectively) in the equator and posterior pole areas of enlarging eyes. Western blot analyses of scleral extracts with an antibody to human MMP-2 reveals immunoreactive bands at 65, 30 and 25 kDa. Zymograms incubated under slightly acidic conditions reveal that, in enlarging eyes, MMP activities at 25 and 28 kDa M(r) are increased in scleral equator and posterior pole (1.6- and 4.5-fold respectively). A TIMP-like protein is also identified in sclera and cornea by Western blot analysis. Finally, retinal-image degradation also increases (~2.6-fold) the activity of a 23.5 kDa serine proteinase in limbus, equator and posterior pole sclera that is inhibited by aprotinin and soybean trypsin inhibitor. Taken together, these results indicate that eye growth induced by retinal-image degradation involves increases in the activities of multiple scleral proteinases that could modify the biomechanical properties of scleral structural components and contribute to tissue remodeling and growth.
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During invasion and metastasis, cancer cells interact closely with the extracellular matrix molecules by attachment, degradation, and migration. We demonstrated previously the local degradation of fluorescently labeled gelatin matrix by cancer cells at invasive membrane protrusions, called invadopodia. Using the newly developed quantitative fluorescence-activated cell sorting-phagocytosis assay and image analysis of localized degradation of fluorescently labeled matrix, we document here that degradation and site- specific removal of cross-linked gelatin matrix is correlated with the extent of phagocytosis in human breast cancer cells. A higher phagocytic capacity is generally associated with increasing invasiveness, documented in other invasion and motility assays as well. Gelatin phagocytosis is time and cell density dependent, and it is mediated by the actin cytoskeleton. Most of the intracellular gelatin is routed to actively acidified vesicles, as demonstrated by the fluorescent colocalization of gelatin with acidic vesicles, indicating the intracellular degradation of the phagocytosed matrix in lysosomes. We show here that normal intracellular routing is blocked after treatment with acidification inhibitors. In addition, the need for partial proteolytic degradation of the matrix prior to phagocytosis is demonstrated by the inhibition of gelatin phagocytosis with different serine and metalloproteinase inhibitors and its stimulation by conditioned medium containing the matrix metalloproteinases MMP-2 and MMP-9. Our results demonstrate that phagocytosis of extracellular matrix is an inherent feature of breast tumor cells that correlates with and may even directly contribute to their invasive capacity. This assay is useful for screening and evaluating potential anti-invasive agents because it is fast, reproducible, and versatile.
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Balancing the competing interests of autonomy and protection of individuals is an escalating challenge confronting an ageing Australian population. Legal and medical professionals are increasingly being asked to determine whether individuals are legally capable to make their own testamentary, financial and/or personal/health care decisions. Diseases such as dementia impact upon cognition which necessitates collaboration between the legal and medical professions to satisfactorily assess the effect of such mentally disabling conditions upon legal competency. Terminological and methodological differences exist between the two professions when assessing capacity in this context which subsequently create miscommunication and misunderstanding. Consequently, it is not necessarily a simple solution for a legal professional to seek the opinion of a medical practitioner. Exacerbating the situation is the fact that no consistent and transparent capacity assessment paradigm currently exists in Australia. Assessments are instead being undertaken on an ad hoc basis dependent upon the skill set of the legal and/or medical professionals involved. A qualitative study seeking the views of legal and medical professionals who practise in this area has been conducted. This incorporated a review of the relevant literature and surveys which informed the semi-structured interviews conducted with 10 legal and 20 medical practitioners. Practitioners were asked whether there is a standard approach to assessment and whether national guidelines would assist. The general consensus was that uniform guidelines would be advantageous. The research also canvassed practitioner views as to the state of the relationship between the professions when assessing capacity. Three promising practices have emerged from this research: first, is the need for the development of national guidelines and supporting principles to satisfactorily assess capacity; second, is the possibility of strengthening the relationship between legal and medical professionals to assist in the satisfactory assessment of legal capacity; and third, the need for increased community education.
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Employee engagement is linked to higher productivity, lower attrition, and improved organizational reputations resulting in increased focus and resourcing by managers to foster an engaged workforce. While drivers of employee engagement have been identified as perceived support, job characteristics, and value congruence, internal communication is theoretically suggested to be a key influence in both the process and maintenance of employee engagement efforts. However, understanding the mechanisms by which internal communication influences employee engagement has emerged as a key question in the literature. The purpose of this research is to investigate whether social factors, namely perceived support and identification, play a mediating role in the relationship between internal communication and engagement. To test the theoretical model, data are collected from 200 non-executive employees using an online self-administered survey. The study applies linear and mediated regression to the model and finds that organizations and supervisors should focus internal communication efforts toward building greater perceptions of support and stronger identification among employees in order to foster optimal levels of engagement.