Intrinsic two-phonon-exchange mechanism of superconductivity and enhancement of Tc

It is shown that the intrinsic two-phonon terms occurring in first order in the electron-phonon interaction Hamiltonian can give rise to (i) an essential doubling of the interaction phase space (BCS cutoff) and (ii) an attractive pairing interaction proportional to the phonon occupation numbers. This suggests a possible enhancement of the superconductive transition temperature in the presence of high-frequency acoustic field.

Improved damping capacity and machinability of graphite particle-aluminum alloy composites

The damping capacity of cast graphitic aluminum alloy composites has been measured using a torsion pendulum at a constant strain amplitude. It was found that flake-graphite particles dispersed in the matrix of aluminum alloys increased the damping capacity; the improvement was greater, the higher the amount of graphite dispersed in the matrix. At sufficiently high graphite contents the damping capacity of graphitic aluminum composites approaches that of cast iron. The ratio between the damping capacity and the density of graphitic aluminum alloys is higher than cast iron, making them very attractive as light-weight, high-damping materials for possible aircraft applications. Machinability tests on graphite particle-aluminum composites, conducted at speeds of 315 sfm and 525 sfm, showed that the chip length decreased with the amount of graphite of a given size. When the size of graphite was decreased, at a given machining speed, the chip length decreased. Metallographic examination shows that graphite particles act as chip breakers, and are frequently sheared parallel to the plane of the

Wrought aluminum-nickel alloys for high strength-high conductivity applications

Aluminum-Nickel alloys ranging from 0.06 pct to 6.1 pct (by wt) Ni have been developed for high strength-high conductivity applications. These alloys were produced by solidification in a permanent mold followed by homogenization, hot extrusion or hot rolling and cold drawing to wire form. This sequence of fabrication a) led to the production of fine fibrous dispersoids of NiAl3 as part of the Al-NiAl3 eutectic during the initial casting operation, b) permitted the retention of fine fibrous dispersiods of NiAl3 produced during casting without any significant coarsening during processing and c) led to uniform dispersion and general alignment of these fibrous dispersoids along a given direction in the product without any measurable fiber-matrix separation, extensive fiber-fragmentation or crack production in the matrix. These alloys can be processed to wire form as easily as aluminum and when processed by the above sequence, possess very attractive combination of high strength-high electrical conductivity. Tensile strengths range from 173 N/mm2 (at 0.6 pct Ni) to 241 N/mm2 (at 6.1 pct Ni) in combination with corresponding conductivity values between 62 pct IACS and 55.5 pct IACS. The wires also possess attractive yield strength; for instance, the 0.2 pct off-set strength of Al-6.1 pct Ni wire is 213 N/mm2. Using simple composite rules, the estimated strength and the conductivity of NiAl3 fibers were found to be 1380 N/mm2 and 18 pct IACS respectively, in these wires.

Halvennettu työ : Pätkätyö ja sukupuoli sopimusyhteiskuntaa edeltävissä työmarkkinakäytännöissä

Unvalued Work. Gender and fragmented labour before national collective bargaining Systematically irregular work creates economic and social insecurity. A novelty? To think that globalisation results in unprecedented labour conditions turns out to be questionable when the idea is put in perspective. In the light of history there is nothing new in the frequency of today s short-term employment, for instance, ranking genders in labour relations in an old custom. Unvalued Work (Halvennettu työ) examines the regulation and management of labour before the time of collective bargaining. In the study present trends engage in a dialogue with empirical findings from the past. Preventing trade unions to take the initiative has been and remains an employer interest. The analysis focuses on female employment in the 1920s and 1930s. The inferences challenge to ask on what conditions the history of Finnish labour relations warrants on the whole speaking of contractual security, stable earnings and regular waged work that provides livelihood. Success in selling one s labour is not synonymous with good employment that yields decent income. Juxtaposing labour relations between the world wars and the 21st century helps us to understand the currently transforming labour market. Present policies are informed by past choices and patterns of thought. Unvalued Work (Halvennettu työ) offers instruments for making sense of today s labour relations.

Essays on corporate governance, stakeholders, and restructuring

This dissertation consists of an introductory section and three theoretical essays analyzing the interaction of corporate governance and restructuring. The essays adopt an incomplete contracts approach and analyze the role of different institutional designs to facilitate the alignment of the objectives of shareholders and management (or employees) over the magnitude of corporate restructuring. The first essay analyzes how a firm's choice of production technology affects the employees' human capital investment. In the essay, the owners of the firm can choose between a specific and a general technology that both require a costly human capital investment by the employees. The specific technology is initially superior in using the human capital of employees but, in contrast to the general technology, it is not compatible with future innovations. As a result, anticipated changes in the specific technology diminish the ex ante incentives of the employees to invest in human capital unless the shareholders grant the employees specific governance mechanisms (a right of veto, severance pay) so as to protect their investments. The results of the first essay indicate that the level of protection that the shareholders are willing to offer falls short of the socially desirable one. Furthermore, when restructuring opportunities become more abundant, it becomes more attractive both socially and from the viewpoint of the shareholders to initially adopt the general technology. The second essay analyzes how the allocation of authority within the firm interacts with the owners' choice of business strategy when the ability of the owners to monitor the project proposals of the management is biased in favor of the status quo strategy. The essay shows that a bias in the monitoring ability will affect not only the allocation of authority within the firm but also the choice of business strategy. Especially, when delegation has positive managerial incentive effects, delegation turns out to be more attractive under the new business strategy because the improved managerial incentives are a way for the owners to compensate their own reduced information gathering ability. This effect, however, simultaneously makes the owners hesitant to switch the strategy since it would involve a more frequent loss of control over the project choice. Consequently, the owners' lack of knowledge of the new business strategy may lead to a suboptimal choice of strategy. The third essay analyzes the implications of CEO succession process for the ideal board structure. In this essay, the presence of the departing CEO on the board facilitates the ability of the board to find a matching successor and to counsel him. However, the ex-CEO's presence may simultaneously also weaken the ability of the board to restructure since the predecessor may use the opportunity to distort the successor's project choice. The results of the essay suggest that the extent of restructuring gains, the firm's ability to hire good outside directors and the importance of board's advisory role affect at which point and for how long the shareholders may want to nominate the predecessor to the board.

An innovative clustering technique for unsupervized learning in the context of remotely sensed earth resources data analysis

A new clustering technique, based on the concept of immediato neighbourhood, with a novel capability to self-learn the number of clusters expected in the unsupervized environment, has been developed. The method compares favourably with other clustering schemes based on distance measures, both in terms of conceptual innovations and computational economy. Test implementation of the scheme using C-l flight line training sample data in a simulated unsupervized mode has brought out the efficacy of the technique. The technique can easily be implemented as a front end to established pattern classification systems with supervized learning capabilities to derive unified learning systems capable of operating in both supervized and unsupervized environments. This makes the technique an attractive proposition in the context of remotely sensed earth resources data analysis wherein it is essential to have such a unified learning system capability.

Studies on Wage Differentials and Labour Market Transitions

This thesis consists of four studies. The first study examines wage differentials between women and men in the Finnish manufacturing sector. A matched employer-employee data set is used to decompose the overall gender wage gap into the contributions of sex differences in human capital, labour market segregation, and residual within-job wage differentials. The topic of the second study is the relationship between the extended unemployment benefits and labour market transitions of older workers. The analysis exploits a quasi-experimental setting caused by a change in the law that raised the eligibility age of workers benefiting from extended benefits. Roughly half of the unemployed workers with extended benefits are estimated to be effectively withdrawn from labour market search. The risk of unemployment declined and the re-employment probability increased among the age groups directly affected by the reform. The third study provides an empirical analysis of a structural equilibrium search model. Estimation results from various model specifications are compared and discussed. The last study is a methodological study where the difficulties of interpreting the results of competing risks hazard models are discussed and a solution for a particular class of models is proposed. It is argued that a common practice of reporting the results of qualitative response models in terms of marginal effects is also useful in the context of competing risks duration models.

Is there an athermal region of plastic flow in metals at intermediate temperatures?

The question of the existence or otherwise of an athermal temperature region of plastic flow in metals is examined. It is suggested that the athermal region is absent in metals with large dislocation densities. Such an explanation is provoked by a fairly recent proposition that the unzipping of attractive junctions is a plausible rate-controlling mechanism at high temperatures.

Assessing taxpayer response to legislative changes: A case study of ‘in-house’ fringe benefits rules

On 22 October 2012, the Australian Federal Government announced the removal of the $1,000 in-house fringe benefits concession when used as part of a salary packaging arrangement. At the time of the announcement, the Federal Government predicted that the removal of the concession would contribute additional tax revenue of $445 million over the following four years as well as an increase of GST payments to the States and Territories. However, anecdotal evidence at the same time indicated that the Australian employer response was to immediately stop providing employees with such in-house fringe benefits via salary sacrificing arrangements. Data presented in this article, collected from a combination of interviews with tax managers of four Australian entities as well as a review of the published archival data, confirms that the abolition of the $1,000 in-house fringe benefits concession was perceived as a negative change, whereby employees were considered the ‘big losers’ despite assertions by the Federal Government to the contrary. Using a conceptual map of tax rule change developed by Oats and Sadler, this article seeks to understand the reasons for this fringe benefits tax change and taxpayer response. In particular, the economic and political factors, and the responses of the relevant taxpayers (employers) are explored. Drawing on behavioural economic concepts, the actions, attitudes and response of employers to the rule change are also examined. The research findings suggest that the decision by Australian employers to cease providing the in-house fringe benefits as part of a salary-packaging arrangement after the legislative amendment was impacted by more than simple rational behaviour.

Regional variation in the composition and structure of mixed-species bird flocks in the Western Ghats and Sri Lanka

Mixed-species bird flocks are attractive models for the investigation of geographical variation in animal communities, as they represent a subset of the avifauna in most forested regions of the world. Yet studies of the regional variation in flock size and the composition of flocks are few, due to the predominance of studies carried out at single study site. Here, we review nine studies of mixed-species flocks conducted at 16 sites along the Western Ghats in India and in Sri Lanka. We find that flock size varies as much within this region as it does globally, with observation time being a confounding variable. Flock composition, however, is predictably related to elevation. Flocks at high elevations (>1200 m) in the Western Ghats strongly resemble flocks at high elevations in the mountain ranges of Sri Lanka in their composition, especially at the family level. We compare these flocks to flocks of other regions and make recommendations on study methodology that can facilitate comparisons across studies.

Engineering the pentose phosphate pathway of Saccharomyces cerevisiae for production of ethanol and xylitol

The baker s yeast Saccharomyces cerevisiae has a long tradition in alcohol production from D-glucose of e.g. starch. However, without genetic modifications it is unable to utilise the 5-carbon sugars D-xylose and L arabinose present in plant biomass. In this study, one key metabolic step of the catabolic D-xylose pathway in recombinant D-xylose-utilising S. cerevisiae strains was studied. This step, carried out by xylulokinase (XK), was shown to be rate-limiting, because overexpression of the xylulokinase-encoding gene XKS1 increased both the specific ethanol production rate and the yield from D xylose. In addition, less of the unwanted side product xylitol was produced. Recombinant D-xylose-utilizing S. cerevisiae strains have been constructed by expressing the genes coding for the first two enzymes of the pathway, D-xylose reductase (XR) and xylitol dehydrogenase (XDH) from the D-xylose-utilising yeast Pichia stipitis. In this study, the ability of endogenous genes of S. cerevisiae to enable D-xylose utilisation was evaluated. Overexpression of the GRE3 gene coding for an unspecific aldose reductase and the ScXYL2 gene coding for a xylitol dehydrogenase homologue enabled growth on D-xylose in aerobic conditions. However, the strain with GRE3 and ScXYL2 had a lower growth rate and accumulated more xylitol compared to the strain with the corresponding enzymes from P. stipitis. Use of the strictly NADPH-dependent Gre3p instead of the P. stipitis XR able to utilise both NADH and NADPH leads to a more severe redox imbalance. In a S. cerevisiae strain not engineered for D-xylose utilisation the presence of D-xylose increased xylitol dehydrogenase activity and the expression of the genes SOR1 or SOR2 coding for sorbitol dehydrogenase. Thus, D-xylose utilisation by S. cerevisiae with activities encoded by ScXYL2 or possibly SOR1 or SOR2, and GRE3 is feasible, but requires efficient redox balance engineering. Compared to D-xylose, D-glucose is a cheap and readily available substrate and thus an attractive alternative for xylitol manufacture. In this study, the pentose phosphate pathway (PPP) of S. cerevisiae was engineered for production of xylitol from D-glucose. Xylitol was formed from D-xylulose 5-phosphate in strains lacking transketolase activity and expressing the gene coding for XDH from P. stipitis. In addition to xylitol, ribitol, D-ribose and D-ribulose were also formed. Deletion of the xylulokinase-encoding gene increased xylitol production, whereas the expression of DOG1 coding for sugar phosphate phosphatase increased ribitol, D-ribose and D-ribulose production. Strains lacking phosphoglucose isomerase (Pgi1p) activity were shown to produce 5 carbon compounds through PPP when DOG1 was overexpressed. Expression of genes encoding glyceraldehyde 3-phosphate dehydrogenase of Bacillus subtilis, GapB, or NAD-dependent glutamate dehydrogenase Gdh2p of S. cerevisiae, altered the cellular redox balance and enhanced growth of pgi1 strains on D glucose, but co-expression with DOG1 reduced growth on higher D-glucose concentrations. Strains lacking both transketolase and phosphoglucose isomerase activities tolerated only low D-glucose concentrations, but the yield of 5-carbon sugars and sugar alcohols on D-glucose was about 50% (w/w).

An engineering or behavioural approach? A study into employee’s perceptions regarding the effectiveness of occupational road safety initiatives

Background and Aims Considerable variation has been documented with fleet safety interventions’ abilities to create lasting behavioural change, and research has neglected to consider employees’ perceptions regarding the effectiveness of fleet interventions. This is a critical oversight as employees’ beliefs and acceptance levels (as well as the perceived organisational commitment to safety) can ultimately influence levels of effectiveness, and this study aimed to examine such perceptions in Australian fleet settings. Method 679 employees sourced from four Australian organisations completed a safety climate questionnaire as well as provided perspectives about the effectiveness of 35 different safety initiatives. Results Countermeasures that were perceived as most effective were a mix of human and engineering-based approaches: - (a) purchasing safer vehicles; - (b) investigating serious vehicle incidents, and; - (c) practical driver skills training. In contrast, least effective countermeasures were considered to be: - (a) signing a promise card; - (b) advertising a company’s phone number on the back of cars for complaints and compliments, and; - (c) communicating cost benefits of road safety to employees. No significant differences in employee perceptions were identified based on age, gender, employees’ self-reported crash involvement or employees’ self-reported traffic infringement history. Perceptions of safety climate were identified to be “moderate” but were not linked to self-reported crash or traffic infringement history. However, higher levels of safety climate were positively correlated with perceived effectiveness of some interventions. Conclusion Taken together, employees believed occupational road safety risks could best be managed by the employer by implementing a combination of engineering and human resource initiatives to enhance road safety. This paper will further outline the key findings in regards to practice as well as provide direction for future research.

Ion heating by the lower hybrid mode

The lower hybrid mode excited in a plasma with cross-field current and density gradient induces an attractive potential between the negative-and positive-energy modes of the plasma. The growth rate is thereby reduced and becomes comparable with the damping rates due to wave-particle interaction. This leads to the saturation of the turbulent field. Some applications have been made to the turbulent heating experiments in plasma where cross-field current is present.

Species-based and community-level approaches to conservation prioritization

One major reason for the global decline of biodiversity is habitat loss and fragmentation. Conservation areas can be designed to reduce biodiversity loss, but as resources are limited, conservation efforts need to be prioritized in order to achieve best possible outcomes. The field of systematic conservation planning developed as a response to opportunistic approaches to conservation that often resulted in biased representation of biological diversity. The last two decades have seen the development of increasingly sophisticated methods that account for information about biodiversity conservation goals (benefits), economical considerations (costs) and socio-political constraints. In this thesis I focus on two general topics related to systematic conservation planning. First, I address two aspects of the question about how biodiversity features should be valued. (i) I investigate the extremely important but often neglected issue of differential prioritization of species for conservation. Species prioritization can be based on various criteria, and is always goal-dependent, but can also be implemented in a scientifically more rigorous way than what is the usual practice. (ii) I introduce a novel framework for conservation prioritization, which is based on continuous benefit functions that convert increasing levels of biodiversity feature representation to increasing conservation value using the principle that more is better. Traditional target-based systematic conservation planning is a special case of this approach, in which a step function is used for the benefit function. We have further expanded the benefit function framework for area prioritization to address issues such as protected area size and habitat vulnerability. In the second part of the thesis I address the application of community level modelling strategies to conservation prioritization. One of the most serious issues in systematic conservation planning currently is not the deficiency of methodology for selection and design, but simply the lack of data. Community level modelling offers a surrogate strategy that makes conservation planning more feasible in data poor regions. We have reviewed the available community-level approaches to conservation planning. These range from simplistic classification techniques to sophisticated modelling and selection strategies. We have also developed a general and novel community level approach to conservation prioritization that significantly improves on methods that were available before. This thesis introduces further degrees of realism into conservation planning methodology. The benefit function -based conservation prioritization framework largely circumvents the problematic phase of target setting, and allowing for trade-offs between species representation provides a more flexible and hopefully more attractive approach to conservation practitioners. The community-level approach seems highly promising and should prove valuable for conservation planning especially in data poor regions. Future work should focus on integrating prioritization methods to deal with multiple aspects in combination influencing the prioritization process, and further testing and refining the community level strategies using real, large datasets.

Negotiation schemes for multi-agent cooperative search

Because of limited sensor and communication ranges, designing efficient mechanisms for cooperative tasks is difficult. In this article, several negotiation schemes for multiple agents performing a cooperative task are presented. The negotiation schemes provide suboptimal solutions, but have attractive features of fast decision-making, and scalability to large number of agents without increasing the complexity of the algorithm. A software agent architecture of the decision-making process is also presented. The effect of the magnitude of information flow during the negotiation process is studied by using different models of the negotiation scheme. The performance of the various negotiation schemes, using different information structures, is studied based on the uncertainty reduction achieved for a specified number of search steps. The negotiation schemes perform comparable to that of optimal strategy in terms of uncertainty reduction and also require very low computational time, similar to 7 per cent to that of optimal strategy. Finally, analysis on computational and communication requirement for the negotiation schemes is carried out.