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21.
One of the most vociferous criticisms of the Internet has always been that it contributes to loneliness among its users. This study analyses results from the World Internet Project, comprised of representative samples from 13 countries (22,002 participants). Thus creating an exceptional international representative sample. In analyzing those results, we argue that in order to achieve a comprehensive understanding of the Internet’s influence over individuals’ social lives; it is essential to consider the different types of social connections that might be influenced by the Internet. We assess the influence of Internet use over social interactions in separate life domains (e.g. with family members; friends; colleagues). Our analysis confirms that Internet usage can actually enhance the social lives of its users. Qualifications to the research are discussed while highlighting the different life domains in which we found significant correlations between Internet usage and increased social interactions.  相似文献   
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How do leadership ratings collected from units operating under stable conditions predict subsequent performance of those units operating under high stress and uncertainty? To examine this question, the authors calculated the predictive relationships for the transformational and transactional leadership of 72 light infantry rifle platoon leaders for ratings of unit potency, cohesion, and performance for U.S. Army platoons participating in combat simulation exercises. Both transformational and transactional contingent reward leadership ratings of platoon leaders and sergeants positively predicted unit performance. The relationship of platoon leadership to performance was partially mediated through the unit's level of potency and cohesion. Implications, limitations, and future directions for leadership research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
23.
Super resolution pitch determination of speech signals   总被引:7,自引:0,他引:7  
Based on a new similarity model for the voice excitation process, a novel pitch determination procedure is derived. The unique features of the proposed algorithm are infinite (super) resolution, better accuracy than the difference limen for F0, robustness to noise, reliability, and modest computational complexity. The algorithm is instrumental to speech processing applications which require pitch synchronous spectral analysis. The computational complexity of the proposed algorithm is well within the capacity of modern digital signal processing (DSP) technology and therefore can be implemented in real time  相似文献   
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Existing buildings constitute a large portion of the UK’s housing stock. Refurbishment of existing buildings can, therefore, have an important role in achieving the UK government’s CO2 reduction targets. While building regulations and rating frameworks mainly focus on the improvements of the operational performance of buildings, Life Cycle Analysis is considered to be a more appropriate framework to account for long–term CO2 savings. This study evaluates a range of retrofit approaches (simple, medium, and deep), in terms of Life Cycle Carbon Footprint applied on a terraced house—one of the most common housing archetypes in London. The initial state of the original building has also been examined assuming three initial states (never refurbished, refurbished in compliance with the 1976 and with the 2000 building regulations). Results showed that for all initial state scenarios, deep retrofit achieved the lowest life cycle carbon emissions, in absolute figures, compared to the simple and medium retrofits. Simple retrofit packages, on the other hand, achieved quick and significant improvements, especially in buildings with poor initial thermal conditions. The study also indicated that retrofit packages applied on highly efficient building fabrics result in longer carbon payback time periods. The study recommends establishing a ‘staggered’ retrofitting approach, which pushes for ‘older building first’ and ‘simple retrofit packages first’, as these gain quick CO2 savings. Deep retrofit packages and treatment of relatively new buildings should be implemented at a later stage, to push buildings further to Zero–Carbon target.

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The discovery and understanding of gecko ‘frictional-adhesion’ adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick–slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick–slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick–slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems.  相似文献   
28.
A general solution procedure, based on the linear theory, is presented for arbitrary shells of revolution subjected to arbitrary axisymmetric dynamic loads. The equations of motion admit shear deformation and rotational inertia. The numerical solution is obtained by Houbolt's method and by finite differences.  相似文献   
29.
Fluorescence lifetime imaging is a very promising imaging method for early detection of malignant tumors. It offers many advantages over conventional fluorescence methods, especially because the acquired signal does not rely on the fluorophore concentration in the tissue. As in all imaging method, the goal is to determine the exact location of a malignant tumor. However, since we are dealing with optical imaging, the inverse problem, i.e., extracting the tumor location coordinates is not an easy task to fulfill. In this paper, we describe an alternative method of interpreting the fluorescence lifetime image. The method extracts four features from each decay curve. We show that from these features one can extract the location of the tumor. The theoretical model is compared to the experimental results obtained from tissue-like phantoms.  相似文献   
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