An activity-based costing model for long-term preservation and dissemination of digital research data: the case of DANS

Financial sustainability is an important attribute of a trusted, reliable digital repository. The authors of this paper use the case study approach to develop an activity-based costing (ABC) model. This is used for estimating the costs of preserving digital research data and identifying options for improving and sustaining relevant activities. The model is designed in the environment of the Data Archiving and Networked Services (DANS) institute, a well-known trusted repository. The DANS–ABC model has been tested on empirical cost data from activities performed by 51 employees in frames of over 40 different national and international projects. Costs of resources are being assigned to cost objects through activities and cost drivers. The ‘euros per dataset’ unit of costs measurement is introduced to analyse the outputs of the model. Funders, managers and other decision-making stakeholders are being provided with understandable information connected to the strategic goals of the organisation. The latter is being achieved by linking the DANS–ABC model to another widely used managerial tool—the Balanced Scorecard (BSC). The DANS–ABC model supports costing of services provided by a data archive, while the combination of the DANS–ABC with a BSC identifies areas in the digital preservation process where efficiency improvements are possible.     

水力压裂优化设计研究及应用

压裂优化设计的主要参数是无因次采液指数、无因次支撑剂数、无因次裂缝导流能力,弄清它们之间的关系是水力压裂优化设计的关键。经对裂缝优化设计的基本理论进行分析,结合自主研发的OptiStim系统,对水力压裂过程展开了研究分析得知,高渗地层采用压裂增产效果优于低渗地层,使用优质支撑剂、增加支撑剂量能提高压后产量。但为优选出最佳的水力压裂设计方案,需要根据油井具体情况,综合考虑各方面因素。     

Students’ thoughts about the importance and costs of their mobile devices’ features and services

In recent years, handheld devices have become one of the fastest growing communication gadgets. Mobile technology is becoming widespread and research in this area is urgently needed. Using a survey instrument, the thoughts of male and female students regarding the importance and costs of mobile devices were investigated. It was found that students tend to consider the following features important: battery life, mp3 player, video camera, photo camera, storage memory, Bluetooth, design and elegance, clock, calendar, organizer and reminder. Also, they are eager to spend an amount of money so as their mobile device to support them. On average, both genders would pay extra money for such features. However, the majority of females think less of the price than males do. On the contrary, most of the respondents do not consider the following important: touch screen, voice commands, chat, teleconference, encryption and cryptography, common use of files, printing. Therefore, they would not spend any money for these features. Interested decision makers would try to increase their interest on such features. Moreover, all respondents appear to own a mobile phone while most of them do not have Internet connection at home. In general, some gender differences are found in the importance and costs of the mobile devices, but they are not statistically significant.     

Influence of zinc oxide and eugenol sealer on concentration of zinc, calcium and copper in rat tissues

A zinc oxide and eugenol root canal sealer (Roth 811) and sterile saline solution were injected into the dorsal thoracic midline of 70 male Wistar-Furth rats. Every day for the next 7 days, 10 animals were sacrificed by either inhalation. The liver, heart, kidneys and brain were removed from the animals and analysed for zinc, calcium and copper concentrations by flame atomic absorption spectrophotometry. The tissue around the injection site was also surgically removed and prepared for histological evaluation under a microscope. The injection of Roth 811 significantly affected the concentrations of zinc, calcium and copper in some of the examined organs, especially on the 4th and 5th day. The inflammatory reaction adjacent to the material was severe during the first 3 days while on the 7th day the presence of connective tissue with collagen formation was observed.     

Inactivation of Escherichia coli K-12 and Listeria innocua in milk using radio frequency (RF) heating

Using a 2 kW, 27.12 MHz RF heater, studies were conducted to evaluate the effectiveness of RF heating in inactivating surrogates of both Listeria and Escherichia coli cells in milk under continuous flow conditions. Depending on product residence time and RF power level, RF heating was found to be capable of inactivating both Listeria and E. coli in milk, with E. coli being the more heat sensitive of the two. For a total residence time of 55.5 s (i.e., 29.5 and 26 s in the applicator and holding tube, respectively), up to 5- and 7-log reductions were found for heating Listeria and E. coli, respectively at 1200 W, and an applicator tube exit temperature of approximately 65 °C. This study demonstrates that RF heating could be used to effectively pasteurize milk by manipulating incident power levels and flow rate. While these studies have been conducted under mild fluid flow (laminar) conditions, further studies are necessary to justify its industrial application using more realistic flow conditions.

Industrial relevance

Radio frequency (RF) heating can provide rapid heating. Compared to the microwave, RF has the added advantage of higher penetration depth. These advantages could be harnessed for pasteurizing large volume liquid foods and, most importantly, RF heating could potentially replace traditional heat exchangers that are easily fouled by products such as milk. This study demonstrates the effectiveness of using RF heating under mild flow conditions to inactivate microorganisms that could contaminate milk.     

Image quality evaluation and patient dose assessment of medical fluoroscopic X-ray systems: a national study

This study presents the results from a survey conducted by the Greek Atomic Energy Commission (GAEC), during the period 1998-2003, in 530 public and private owned fluoroscopic X-ray systems in Greece. Certain operational parameters for conventional and remote control systems were assessed, according to a quality control protocol developed by GAEC on the basis of the current literature. Public (91.5%) and private (81.5%) owned fluoroscopic units exhibit high-contrast resolution values over 1 lp mm(-1). Moreover, 88.5 and 87.1% of the fluoroscopic units installed in the public and private sector, respectively, present Maximum Patient Entrance Kerma Rate values lower than 100 mGy min(-1). Additionally, 68.3% of the units assessed were found to perform within the acceptance limits. Finally, the third quartile of the Entrance Surface Dose Rate distribution was estimated according to the Dose Reference Level definition and found equal to 35 mGy min(-1).     

Multiple response learning automata.

Learning Automata update their action probabilites on the basis of the response they get from a random environment. They use a reward adaptation rate for a favorable environment's response and a penalty adaptation rate for an unfavorable environment's response. In this correspondence, we introduce Multiple Response learning automata by explicitly classifying the environment responses into a reward (favorable) set and a penalty (unfavorable) set. We derive a new reinforcement scheme which uses different reward or penalty rates for the corresponding reward (favorable) or penalty (unfavorable) responses. Well known learning automata, such as the L(R-P);L(R-I); L(R-eP) are special cases of these Multiple Response learning automata. These automata are feasible at each step, nonabsorbing (when the penalty functions are positive), and strictly distance diminishing. Finally, we provide conditions in order that they are ergodic and expedient.     

Dynamic routing and admission control for virtual circuit networks

The dynamic joint routing and admission control problem in multiple class multiple source-destination virtual circuit networks is considered. A nonlinear dynamic queueing model for virtual circuit networks that considers the dynamic interaction among the virtual circuit and packet processes is introduced. Then a multi-objective cost function of rejecting and maintaining virtual circuits, as well as of delaying and servicing packets is defined. The combined problem is formulated as an optimal control problem. Necessary optimality conditions are provided by Pontryagin's maximum principle. Sufficient optimality conditions based on the convexity of the Hamiltonian function are also given. For the finite horizon, the optimal controls can be found after numerically solving a Two-Point Boundary-Value Problem. For the longrun stationary equilibrium, the state-dependent routing and admission controls are derived.This work was supported by the National Science Foundation under Grant DMC-8452002 together with matching funds from AT&T Information Systems.