967 resultados para Focal Point
Resumo:
A polymer containing electron-rich aromatic donors (1,5-dialkoxynaphthalene (DAN)) was coerced into a folded state by an external folding agent that contained an electron-deficient aromatic acceptor (pyromellitic diimide (PM)) unit. The donor-containing polymer was designed to carry a tertiary amine moiety in the linking segment, which served as an H-bonding site for reinforcing the interaction with the acceptor containing folding agent that also bore a carboxylic acid group. The H-bonding interaction of the carboxylic acid and the tertiary amine brings the PDI unit between two adjacent DAN units along the polymer backbone to induce charge-transfer (C-T) interactions, and this in turn causes the polymer chain to form a pleated structure. Evidence for the formation of such a pleated structure was obtained from NMR titration studies and also by monitoring the C-T band in their UV-visible spectra. By varying the length of the segment that links the PDI acceptor to the carboxylic acid group, we showed that the most effective folding agent was the one that had a single carbon spacer, as evident from the highest value of the association constant. Control experiments with propionic acid clearly demonstrated the importance of the additional C-T interactions for venerating the folded structures. Further, solution viscosity measurements in the presence of varying amounts of the folding agent revealed a gradual stiffening of the chain in the case of the PDI carrying carboxylic acid, whereas no such affect was seen in the case of simple propionic acid. These observations were supported by D FT calculations of the interactions of a dimeric model of the polymer with the various folding agents; here too the stability of the complex was seen to be highest in the case of the single carbon spacer.
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We propose and demonstrate a dynamic point spread function (PSF) for single and multiphoton fluorescence microscopy. The goal is to generate a PSF whose shape and size can be maneuvered from highly localized to elongated one, thereby allowing shallow-to-depth excitation capability during active imaging. The PSF is obtained by utilizing specially designed spatial filter and dynamically altering the filter parameters. We predict potential applications in nanobioimaging and fluorescence microscopy.
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We propose and demonstrate a dynamic point spread function (PSF) for single and multiphoton fluorescence microscopy. The goal is to generate a PSF whose shape and size can be maneuvered from highly localized to elongated one, thereby allowing shallow-to-depth excitation capability during active imaging. The PSF is obtained by utilizing specially designed spatial filter and dynamically altering the filter parameters. We predict potential applications in nanobioimaging and fluorescence microscopy.
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The paper presents simple graphical procedures for position synthesis of plane linkage mechanisms to generate functions of two independent variables. The procedures are based on point-position reduction and permit synthesis of the linkage to satisfy up to six arbitrarily selected precision positions.
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The paper presents simple graphical procedures for the position synthesis of plane linkage mechanisms with sliding inputs and output to generate functions of two independent variables. The procedures are based on point position reduction and permit synthesis of the linkage to satisfy up to five arbitrarily selected precision positions.
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The aim of the study was to explore the importance of evaluating leadership criteria in Finland at leader/subordinate levels of the insurance industry. The overall purpose of the thesis is tackled and analyzed from two different perspectives: - by examining the importance of the leadership criteria and style of Finnish insurance business leaders and their subordinates - by examining the opinions of insurance business leaders regarding leadership criteria in two culturally different countries: the US and Finland. This thesis consists of three published articles that scrutinise the focal phenomena both theoretically and empirically. The main results of the study do not lend support to the existence of a universal model of leadership criteria in the insurance business. As a matter of fact, the possible model seems to be based more on the special organizational and cultural circumstances of the country in question. The leadership criteria seem to be quite stable irrespective of the comparatively short research time period (3–5 years) and hierarchical level (subordinate/leader). Leaders have major difficulties in changing their leadership style. In fact, in order to bring about an efficient organizational change in the company you have to alternate the leader. The cultural dimensions (cooperation and monitoring) identified by Finnish subordinates were mostly in line with those of their managers, whilst emphasizing more the aspect of monitoring employees, which could be seen from their point of view as another element of managers’ optimizing/efficiency requirements. In Finnish surveys the strong emphasis on cooperation and mutual trust become apparent by both subordinates and managers. The basic problem is still how to emphasize and balance them in real life in such a way that both parties are happy to work together on a common basis. The American surveys suggests hypothetically that in a soft market period (buyer’s market) managers employ a more relationship-oriented leadership style and correspondingly adapt their leadership style to a more task-oriented approach in a hard market phase (seller’s market). In making business better Finnish insurance managers could probably concentrate more on task-oriented items such as reviewing, budgeting, monitoring and goal-orientation. The study also suggests that the social safety net of the European welfare state ideology has so far shielded the culture-specific sense of social responsibility of Finnish managers from the hazards of free competition and globalization.
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Service researchers have repeatedly claimed that firms should acquire customer information in order to develop services that fit customer needs. Despite this, studies that would concentrate on the actual use of customer information in service development are lacking. The present study fulfils this research gap by investigating information use during a service development process. It demonstrates that use is not a straightforward task that automatically follows the acquisition of customer information. In fact, out of the six identified types of use, four represent non usage of customer information. Hence, the study demonstrates that the acquisition of customer information does not guarantee that the information will actually be used in development. The current study used an ethnographic approach. Consequently, the study was conducted in the field in real time over an extensive period of 13 months. Participant observation allowed direct access to the investigated phenomenon, i.e. the different types of use by the observed development project members were captured while they emerged. In addition, interviews, informal discussions and internal documents were used to gather data. A development process of a bank’s website constituted the empirical context of the investigation. This ethnography brings novel insights to both academia and practice. It critically questions the traditional focus on the firm’s acquisition of customer information and suggests that this focus ought to be expanded to the actual use of customer information. What is the point in acquiring costly customer information if it is not used in the development? Based on the findings of this study, a holistic view on customer information, “information in use” is generated. This view extends the traditional view of customer information in three ways: the source, timing and form of data collection. First, the study showed that the customer information can come explicitly from the customer, from speculation among the developers or it can already exist implicitly. Prior research has mainly focused on the customer as the information provider and the explicit source to turn to for information. Second, the study identified that the used and non-used customer information was acquired both previously, and currently within the time frame of the focal development process, as well as potentially in the future. Prior research has primarily focused on the currently acquired customer information, i.e. within the timeframe of the development process. Third, the used and non-used customer information was both formally and informally acquired. In prior research a large number of sophisticated formal methods have been suggested for the acquisition of customer information to be used in development. By focusing on “information in use”, new knowledge on types of customer information that are actually used was generated. For example, the findings show that the formal customer information acquired during the development process is used less than customer information already existent within the firm. With this knowledge at hand, better methods to capture this more usable customer information can be developed. Moreover, the thesis suggests that by focusing stronger on use of customer information, service development processes can be restructured in order to facilitate the information that is actually used.
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he growth of high-performance application in computer graphics, signal processing and scientific computing is a key driver for high performance, fixed latency; pipelined floating point dividers. Solutions available in the literature use large lookup table for double precision floating point operations.In this paper, we propose a cost effective, fixed latency pipelined divider using modified Taylor-series expansion for double precision floating point operations. We reduce chip area by using a smaller lookup table. We show that the latency of the proposed divider is 49.4 times the latency of a full-adder. The proposed divider reduces chip area by about 81% than the pipelined divider in [9] which is based on modified Taylor-series.
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We have presented a new low dissipative kinetic scheme based on a modified Courant Splitting of the molecular velocity through a parameter φ. Conditions for the split fluxes derived based on equilibrium determine φ for a one point shock. It turns out that φ is a function of the Left and Right states to the shock and that these states should satisfy the Rankine-Hugoniot Jump condition. Hence φ is utilized in regions where the gradients are sufficiently high, and is switched to unity in smooth regions. Numerical results confirm a discrete shock structure with a single interior point when the shock is aligned with the grid.
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The electrical capacitance and resistance of the binary liquid mixture cyclohexane + acetonitrile are measured in the one phase and two phase regions at spot frequencies between 5 kHz and 100 kHz. This sample has a very low gravity affected (∼0.6 mK) region. In one phase region the capacitance data show a sharp, ∼0.7% increase above background within 0.5 degrees of Tc whereas the resistance has a smooth increase of ∼1.5% above background in a (T−Tc) range of 4 degrees. Two phase values of capacitance and resistance from the coexisting phases are used to determine the critical parameters Tc (critical temperature), Rc (resistance at Tc) and Cc (capacitance at Tc). A precise knowledge of these parameters reduces the uncertainty on the critical exponent 0 for C and R. The one phase capacitance data fit to an (1 - α) exponent in a limited temperature range of 0.2 degrees. Resistance data strongly support an (1 - α) exponent over the entire 5 degree range.
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An analysis is performed to study the unsteady laminar incompressible boundary-layer flow of an electrically conducting fluid in a cone due to a point sink with an applied magnetic field. The unsteadiness in the flow is considered for two types of motion, viz. the motion arising due to the free stream velocity varying continuously with time and the transient motion occurring due to an impulsive change either in the strength of the point sink or in the wall temperature. The partial differential equations governing the flow have been solved numerically using an implicit finite-difference scheme in combination with the quasilinearization technique. The magnetic field increases the skin friction but reduces heat transfer. The heat transfer and temperature field are strongly influenced by the viscous dissipation and Prandtl number. The velocity field is more affected at the early stage of the transient motion, caused by an impulsive change in the strength of the point sink, as compared to the temperature field. When the transient motion is caused by a sudden change in the wall temperature, both skin friction and heat transfer take more time to reach a new steady state. The transient nature of the flow and heat transfer is active for a short time in the case of suction and for a long time in the case of injection. The viscous dissipation prolongs the transient behavior of the flow.
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Semi-similar solutions of the unsteady compressible laminar boundary layer flow over two-dimensional and axisymmetric bodies at the stagnation point with mass transfer are studied for all the second-order boundary layer effects when the free stream velocity varies arbitrarily with time. The set of partial differential equations governing the unsteady compressible second-order boundary layers representing all the effects are derived for the first time. These partial differential equations are solved numerically using an implicit finite-difference scheme. The results are obtained for two particular unsteady free stream velocity distributions: (a) an accelerating stream and (b) a fluctuating stream. It is observed that the total skin friction and heat transfer are strongly affected by the surface mass transfer and wall temperature. However, their variation with time is significant only for large times. The second-order boundary layer effects are found to be more pronounced in the case of no mass transfer or injection as compared to that for suction. Résumé Des solutions semi-similaires d'écoulement variable compressible de couche limite sur des corps bi-dimensionnels thermique, sont étudiées pour tous les effets de couche limite du second ordre, lorsque la vitesse de l'écoulement libre varie arbitrairement avec le temps. Le systéme d'équations aux dérivées partielles représentant tous les effets est écrit pour la premiére fois. On le résout numériquement á l'aide d'un schéma implicite aux différences finies. Les résultats sont obtenus pour deux cas de vitesse variable d'écoulement libre: (a) un écoulement accéléré et (b) un écoulement fluctuant. On observe que le frottement pariétal total et le transfert de chaleur sont fortement affectés par le transfert de masse et la température pariétaux. Néanmoins, leur variation avec le temps est sensible seulement pour des grandes durées. Les effets sont trouvés plus prononcés dans le cas de l'absence du transfert de masse ou de l'injection par rapport au cas de l'aspiration.
Resumo:
All the second-order boundary-layer effects on the unsteady laminar incompressible flow at the stagnation-point of a three-dimensional body for both nodal and saddle point regions have been studied. It has been assumed that the free-stream velocity, wall temperature and mass transfer vary arbitrarily with time. The effect of the Prandtl number has been taken into account. The partial differential equations governing the flow have been derived for the first time and then solved numerically unsteady free-stream velocity distributions, the nature of the using an implicit finite-difference scheme. It is found that the stagnation point and the mass transfer strongly affect the skin friction and heat transfer whereas the effects of the Prandtl number and the variation of the wall temperature with time are only on the heat transfer. The skin friction due to the combined effects of first- and second-order boundary layers is less than the skin friction due to, the first-order boundary layers whereas the heat transfer has the opposite behaviour. Suction increases the skin friction and heat transfer but injection does the opposite
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We report preliminary experiments on the ternary-liquid mixture, methyl ethyl ketone (MEK)+water (W)+secondary butyl alcohol (sBA)-a promising system for the realization of the quadruple critical point (QCP). The unusual tunnel-shaped phase diagram shown by this system is characterized and visualized by us in the form of a prismatic phase diagram. Light-scattering experiments reveal that (MEK+W+sBA) shows near three-dimensional-Ising type of critical behavior near the lower critical solution temperatures, with the susceptibility exponent (gamma) in the range of 1.217 <=gamma <= 1.246. The correlation length amplitudes (xi(o)) and the critical exponent (nu) of the correlation length (xi) are in the ranges of 3.536 <=xi(o)<= 4.611 A and 0.619 <=nu <= 0.633, respectively. An analysis in terms of the effective susceptibility exponent (gamma(eff)) shows that the critical behavior is of the Ising type for MEK concentrations in the ranges of 0.1000 <= X <= 0.1250 and X >= 0.3000. But, for the intermediate range of 0.1750 <= X < 0.3000, the system shows a tendency towards mean-field type of critical behavior. The advantages of the system (MEK+W+sBA) over the system (3-methylpyridine+water+heavy water+potassium Iodide) for the realization of a QCP are outlined.
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In Finland, specialized studies in social work (professional licentiate education) were begun in the year 2000. The education is targeted at experienced social workers and leads to a licentiate degree (a degree between master s and doctorate). In this study, the experiences of members of the first study cohort, specializing in social work with children and young people, are examined. The study s theoretical frame of reference is based on the morphogenetic approach, developed by British sociologist Margaret Archer. In it, the potential powers of both an agent as well as social and cultural structures are considered important and worth taking into account. Archer sees reflexivity, a person s ability to analyze herself/himself, as an essential starting point for agency. Thanks to reflexivity, people are able to engage in internal conversations , discuss the concerns that are important to them and form agential projects . In Archer s theory, the social structures and traits of the cultural system are seen as having potential power in relation to people s agential projects; these powers can enable but also restrain the realization of the projects. On the other hand, individuals can try to review the factors affecting their agential projects and find ways of action that facilitate them. The research task is to study the self-understanding of social work professionals in the 21st century, the issues and goals professionally important for them, as well as the contexts framing the realization of these goals. The research questions are as follows: 1) What kind of internal conversations, concerns and agential projects related to their work did the professionals taking part in licentiate education bring to light? 2) What kind of enabling and restraining factors can be identified in their situations? And 3) What kind of social structures and traits related to the cultural system are connected to these factors? The research material was collected by interviewing the students in different phases of their education. In 2001 and 2004 all members of the study group (n = 25) were interviewed. In 2007, 13 students took part. The themes of the internal conversations brought to light in the interviews were divided into four broad thematic categories: professional development, the position of children in social work, multiprofessional work and structural social work. In relation to these themes the students formed different kinds of agential projects. In addition, the study reveals several cultural and social structures that have enabled but also restrained the realization of the agential projects. These structures are linked, for example, to the relations between employees and employers, students and teachers, children and adults as well as between the representatives of different professions. Working conditions which social workers often consider weak are discussed as a focal issue related to many themes. These working conditions become evident, for example, in the great imbalance which exists between the professional tasks and the amount of time that social workers have for them. Difficult situations arise when social workers feel they cannot reach the goals that are professionally important to them because of the strict external conditions of the work.