Travelling salesman problem tools for microcomputers

The problem of determining minimum total distance to be travelled by a salesman, who is to visit given cities each only once (i.e. the travelling salesman problem) is one of the most studied problems in computational mathematics. Finding an exact solution is not only intractably difficult, but also exceedingly costly. However, we implemented efficient optimal algorithms for both symmetric and asymmetric distance problems. The programs implemented can solve problems up to 180 cities in reasonable computer time.     

Synthesis and Physical Studies of the Organic Salts of Pindolol: Pindolol Benzoate and Pindolol 2-Methoxyphenylacetate

In order to investigate the formation of organic salts of drugs, two salts of pindolol were prepared using salt-forming agents which were crystalline and suitable for physical studies in the solid state. The stoichiometry of the products, pindolol benzoate and pindolol 2-methoxyphenylacetate, was established by elemental analysis. The precipitates formed were assessed by differential scanning calorimetry (DSC), thermogravimetry (TG), x-ray powder diffractometry (XRPD) and Fourier transform-infrared spectrometry (FT-IR). According to the TG and DSC curves, there was no water of crystallization in the precipitates, and the products were thermally stable. Both precipitates gave one sharp melting endotherm which differed from the endotherms of the starting compounds. The x-ray dipaction pattern of the precipitates direred clearly from those of the starting materials, acid and base. The products showed absorption by FT-IR typical of carboxylic acid salts at about 1640-1540 cm^-1. The carbonyl absorption indicative of the carboxylic acid group of benzoic acid or 2-methonyphenylacetic acid was not detectable in the spectra of the precipitates. All this indicates that two new crystalline organic salts (1:1) were formed during the syntheses.     

Dopamine release during ethanol drinking in AA rats

The dopamine overflow in the nucleus accumbens of rats from the high alcohol drinking AA line was measured by microdialysis before, during, and after one-half hour sessions of cued drinking of ethanol flavored with saccharin and peppermint or, as a control, saccharin-peppermint drinking. The animals had had extensive previous experience with ethanol drinking. Self-administration of the ethanol solution did not raise the dopamine level substantially: there was a small (17%) but significant increase only during the first 10 min after the onset of drinking. Giving the rats a cue for ethanol, which was part of their daily routine drinking regime, did not raise the dopamine level before ethanol was presented to the rats (i.e., during "anticipation"). The results are consistent with our previous studies showing a lack of a large ethanol-induced dopamine response in rats with previous experience of drinking ethanol and with the idea that although dopamine may play some role in alcohol drinking, it is not the central substrate producing the reinforcement from ethanol in AA rats.     

A coarse-grain reconfigurable architecture for multimedia applications supporting subword and floating-point calculations

Signal processors exploiting ASIC acceleration suffer from sky-rocketing manufacturing costs and long design cycles. FPGA-based systems provide a programmable alternative for exploiting computation parallelism, but the flexibility they provide is not as high as in processor-oriented architectures: HDL or C-to-HDL flows still require specific expertise and a hardware knowledge background. On the other hand, the large size of the configuration bitstream and the inherent complexity of FPGA devices make their dynamic reconfiguration not a very viable approach. Coarse-grained reconfigurable architectures (CGRAs) are an appealing solution but they pose implementation problems and tend to be application specific. This paper presents a scalable CGRA which eases the implementation of algorithms on field programmable gate array (FPGA) platforms. This design option is based on two levels of programmability: it takes advantage of performance and reliability provided by state-of-the-art FPGA technology, and at the same time it provides the user with flexibility, performance and ease of reconfiguration typical of standard CGRAs. The basic cell template provides advanced features such as sub-word SIMD integer and floating-point computation capabilities, as well as saturating arithmetic. Multiple reconfiguration contexts and partial run-time reconfiguration capabilities are provided, tackling this way the problem of high reconfiguration overhead typical of FPGAs. Selected instances of the proposed architecture have been implemented on an Altera Stratix II EP2S180 FPGA. On this system, we mapped some common DSP, image processing, 3D graphics and audio compression algorithms in order to validate our approach and to demonstrate its effectiveness by benchmarking the benefits achieved.     

A coarse-grain reconfigurable architecture for multimedia applications featuring subword computation capabilities

This paper presents the design and the implementation of a coarse-grain reconfigurable machine used as an accelerator for a programmable RISC core, to speed up the execution of computationally demanding tasks like multimedia applications. We created a VHDL model of the proposed architecture and implemented it on a FPGA board for prototyping purposes; then we mapped on our architecture some DSP and image processing algorithms as a benchmark. In particular, we provided the proposed architecture with subword computation capabilities, which turns out to be extremely effective especially when dealing with image processing algorithms, achieving significant benefits in terms of speed and efficiency in resource usage. To create the configuration bitstream (configware) we created a tool based on a graphical user interface (GUI) which provides a first step towards the automation of the programming flow of our design: the tool is meant to ease the life of the programmer, relieving him from the burden of calculating the configuration bits by hand. Synthesis results indicate that the area occupation and the operating frequency of our design are reasonable also when compared to other similar design. In addition to this, the amount of clock cycles taken by our machine to perform a given algorithm is orders of magnitude smaller than the one required by a corresponding software implementation on a RISC microprocessor.     

Guidance in computer-supported collaborative inquiry learning: Capturing aspects of affect and teacher support in science classrooms

International Journal of Computer-Supported Collaborative Learning - Technology-enhanced collaborative inquiry learning has gained a firm position in curricula across disciplines and educational...     

Nature and Criteria of Systems Models in the Social Sciences

Abstract

This paper is an attempt to present an overview of the various meanings in which the concept of model is being employed in scientific literature. Particular emphasis is laid upon systems models and their characteristic features from the viewpoint of social science applications. The criteria of models in the pursuit of such classic goals as explanation and prediction are discussed. It turns out that the criteria of goodness of models should be different in explanation, prediction and action (or policy-making). It is argued that the organizational aspects of models deserve a careful attention because much of what is known about social reality is related to organization. Furthermore, most of what can be done about social reality is concerned with the component coupling structure of systems. Some illustrations from the social science literature are discussed in order to support the arguments of the paper.     

The association of distress and sleeping problems with physicians’ intentions to change profession: The moderating effect of job control.

The present study examined whether job control moderated the association between stress indicators (distress and sleeping problems) and intentions to change profession among 2,650 Finnish physicians. Ordinal logistic regression analysis was applied. The authors found that high levels of distress and sleeping problems were associated with higher levels of intentions to change profession, whereas high job control was associated with lower levels of intentions to change profession even after adjusting for the effects of gender, age, and employment sector. In addition, high job control was able to mitigate the positive association that distress and sleeping problems had with intentions to change profession. Our findings highlight the importance of offering more job control to physicians to prevent unnecessary physician turnover. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Site managers’ daily work and the uses of building information modelling in construction site management

The use of building information modelling (BIM) and related software tools is increasingly expanding in the work of site managers in construction projects. The early uses of BIM in the actual tasks of site managers are explored by examining the utilization of BIM in their work and the challenges in the deployment of the new digital tools for traditional project collaboration. The ethnographic method of the study consists of shadowing the site managers’ work. The site managers actively used BIM and found it beneficial for their daily work. However, the use of BIM in construction sites is still limited because only a few managers have the competence to use BIM software tools, mobile tools are lacking, and the information content of the models needed for construction work is insufficient.     

Characterization and properties of metallic iron nanoparticles: spectroscopy, electrochemistry, and kinetics

There are reports that nano-sized zero-valent iron (Fe0) exhibits greater reactivity than micro-sized particles of Fe0, and it has been suggested that the higher reactivity of nano-Fe0 may impart advantages for groundwater remediation or other environmental applications. However, most of these reports are preliminary in that they leave a hostof potentiallysignificant(and often challenging) material or process variables either uncontrolled or unresolved. In an effort to better understand the reactivity of nano-Fe0, we have used a variety of complementary techniques to characterize two widely studied nano-Fe0 preparations: one synthesized by reduction of goethite with heat and H2 (Fe(H2)) and the other by reductive precipitation with borohydride (Fe(BH)). Fe(H2) is a two-phase material consisting of 40 nm alpha-Fe0 (made up of crystals approximately the size of the particles) and Fe3O4 particles of similar size or larger containing reduced sulfur; whereas Fe(BH) is mostly 20-80 nm metallic Fe particles (aggregates of <1.5 nm grains) with an oxide shell/coating that is high in oxidized boron. The FeBH particles further aggregate into chains. Both materials exhibit corrosion potentials that are more negative than nano-sized Fe2O3, Fe3O4, micro-sized Fe0, or a solid Fe0 disk, which is consistent with their rapid reduction of oxygen, benzoquinone, and carbon tetrachloride. Benzoquinone-which presumably probes inner-sphere surface reactions-reacts more rapidly with FeBH than Fe(H2), whereas carbon tetrachloride reacts at similar rates with FeBH and Fe(H2), presumably by outer-sphere electron transfer. Both types of nano-Fe0 react more rapidlythan micro-sized Fe0 based on mass-normalized rate constants, but surface area-normalized rate constants do not show a significant nano-size effect. The distribution of products from reduction of carbon tetrachloride is more favorable with Fe(H2), which produces less chloroform than reaction with Fe(BH).