Duration and cost variability of construction activities: an empirical study

The unique nature of construction projects can mean that construction activities often suffer from duration and cost variability. Because this variability is unplanned, it can present a problem when attempting to complete a project on time and on budget. Various factors causing this variability have been identified in the literature, but they predominantly refer to the nature and/or context of the whole project rather than specific activities. In this paper, the order of magnitude of and correlation between activity duration and cost variability is analyzed in 101 construction projects with over 5,000 activities. To do this, the first four moments (mean, standard deviation, skewness, and kurtosis) of actual versus planned duration and cost (log) ratios are analyzed by project, phase of execution, and activity type. Results suggest that, contrary to common wisdom, construction activities do not end late on average. Instead, the large variability in the activity duration is the major factor causing significant project delays and cost overruns. The values of average activity duration and cost variability gathered in this study will also serve as a reference for construction managers to improve future construction planning and project simulation studies with more realistic data

Microbiological and structural aspects of granular sludge from autotrophic denitrifying reactors.

Denitrification is applied in the tertiary treatment of wastewater to reduce N-pollutants. Fluorescence in situ hybridisation (FISH), CARD (catalyzed reporter deposition)-FISH, cloning, and scanning electron microscopy (SEM) were applied to follow the evolution of the microbial composition and structure of granular sludge in autotrophic denitrifying bioreactors fed with nitrate and thiosulfate. With this goal, FISH oligonucleotide probes for the autotrophic denitrifiers, Thiobacillus denitrificans and Thiomicrospira denitrificans, were designed and their utility tested. CARD-FISH and cloning data showed that bacterial diversity changed with bioreactor operation time. After 110 days of operation, the abundance of Thiobacillus denitrificans cells increased considerably: from 1 to 35% of total DAPI-stained cells and from no isolated clones to 30% of the total positives clones. This fact strongly suggests that this microorganism played a dominant role in the autotrophic denitrification. The Archaeal diversity remained almost unchanged and it was mainly represented by Methanosaeta soehngenii. Scanning electron microscopy results indicated a considerable loss in the integrity of the sludge granules during the operation, with risk of sludge buoyancy.pre-print370 K

Dynamically biased statistical model for the ortho/para conversion in the H2 + H3+ → H3+ + H2 reaction

In this work we present a dynamically biased statistical model to describe the evolution of the title reaction from statistical to a more direct mechanism, using quasi-classical trajectories (QCT). The method is based on the one previously proposed by Park and Light [J. Chem. Phys. 126, 044305 (2007)10.1063/1.2430711]. A recent global potential energy surface is used here to calculate the capture probabilities, instead of the long-range ion-induced dipole interactions. The dynamical constraints are introduced by considering a scrambling matrix which depends on energy and determine the probability of the identity/hop/exchange mechanisms. These probabilities are calculated using QCT. It is found that the high zero-point energy of the fragments is transferred to the rest of the degrees of freedom, what shortens the lifetime of H 5+ complexes and, as a consequence, the exchange mechanism is produced with lower proportion. The zero-point energy (ZPE) is not properly described in quasi-classical trajectory calculations and an approximation is done in which the initial ZPE of the reactants is reduced in QCT calculations to obtain a new ZPE-biased scrambling matrix. This reduction of the ZPE is explained by the need of correcting the pure classical level number of the H 5+ complex, as done in classical simulations of unimolecular processes and to get equivalent quantum and classical rate constants using Rice-Ramsperger-Kassel-Marcus theory. This matrix allows to obtain a ratio of hop/exchange mechanisms, α(T), in rather good agreement with recent experimental results by Crabtree [J. Chem. Phys. 134, 194311 (2011)10.1063/1.3587246] at room temperature. At lower temperatures, however, the present simulations predict too high ratios because the biased scrambling matrix is not statistical enough. This demonstrates the importance of applying quantum methods to simulate this reaction at the low temperatures of astrophysical interestThis work has been supported by the program CONSOLIDER-INGENIO 2010 of Ministerio de Ciencia e Innovación under Grant No. CSD2009-00038, entitled “Molecular strophysics: the Herschel and Alma era,” and by Grant Nos. FIS2011-29596-C02 and QCQ2008-02578, and by Comunidad Autónoma de Madrid (CAM) under Grant No. S-2009/MAT/146

Continuous and Localized Mn Implantation of ZnO

We present results derived from continuous and localized 35 keV (55)Mn(+) ion implantations into ZnO. Localized implantations were carried out by using self-ordered alumina membranes as masks leading to ordered arrays of implanted volumes on the substrate surfaces. Defects and vacancies in the small implantation volumes of ZnO were generated due to the implantation processes besides the creation of new phases. Rapid thermal annealing was applied in the case of continuous implantation. The samples were characterized by HRSEM, GIXRD, Raman spectroscopy and RBS/C. Magnetic characterization of the samples pointed out appreciable differences among the samples obtained by the different implantation methods. This fact was mainly attributed to the different volume/surface ratios present in the implanted zones as well as to the increase of Mn atom concentrations along the grain frontiers in the nanostructured surfaces. The samples also showed a ferromagnetic transition phase at temperature value higher than room temperature

A quantitative analysis of cold water for human consumption in hospitals in Spain

An estimation of the water used for human consumption in hospitals is essential to determine possible savings and to fix criteria to improve the design of new water consumption models.The present work reports on cold water for human consumption (CWHC) in hospitals in Spain and determines the possible savings. In the period of 2005–2012, 80 Eco-Management and Audit Schemes (EMAS) from20 hospitals were analysed. The results conclude that the average annual consumption of CWHC is 1.59m3/m2 (with a standard deviation of 0.48 m3/m2), 195.85 m3/bed (standard deviation 70.07 m3/bed), or 53.69 m3/worker (standard deviation 16.64 m3/worker). The results demonstrate the possibility of saving 5,600,000m3 of water per year. Assuming the cost of water as approximately 1.22 €/m3, annual savings are estimated as 6,832,000 €. Furthermore, 2,912MWh of energy could be saved, and the emission of 22,400 annual tonnes of CO2 into the atmosphere could be avoided

Silica final lens performance in laser fusion facilities: HiPER and LIFE

Nowadays, the projects LIFE (Laser Inertial Fusion Energy) in USA and HiPER (High Power Laser Energy Research) in Europe are the most advanced ones to demonstrate laser fusion energy viability. One of the main points of concern to properly achieve ignition is the performance of the final optics (lenses) under the severe irradiation conditions that take place in fusion facilities. In this paper, we calculate the radiation fluxes and doses as well as the radiation-induced temperature enhancement and colour centre formation in final lenses assuming realistic geometrical configurations for HiPER and LIFE. On these bases, the mechanical stresses generated by the established temperature gradients are evaluated showing that from a mechanical point of view lenses only fulfill specifications if ions resulting from the imploding target are mitigated. The absorption coefficient of the lenses is calculated during reactor startup and steady-state operation. The obtained results evidence the necessity of new solutions to tackle ignition problems during the startup process for HiPER. Finally, we evaluated the effect of temperature gradients on focal length changes and lens surface deformations. In summary, we discuss the capabilities and weak points of silica lenses and propose alternatives to overcome predictable problems

The effects of a high-protein, high-calorie, fiber- and fructo-oligosaccharide-enriched enteral formula on nutritional status, bowel habits and tolerance: Safety and effectiveness of enteral nutrition in elderly spanish patients (Sens study)

Background: Enteral nutrition (EN) is an effective nutritional intervention for patients at risk of malnutrition or malnourished. However, complications such as gastrointestinal intolerance, hyperglycemia or refeeding syndrome can be triggered by EN. Aim: To investigate the effects of a tube feeding formula (TFF) on patients’ nutritional status, biochemical status, bowel habits and safety. Methodology: Observational, prospective and multicenter study. Patients = 18 years, undernourished or at nutritional risk, who were prescribed a high-calorie, high-protein, fiber-fortified TFF were included. Patients were evaluated over a period of eight weeks (baseline [V1], four weeks [V2] and eight weeks [V3]). Results: A statistically significant increase in weight (1.5 kg), body mass index (0.6 kg/m2) and nutritional intake (59.7 kcal/day) was observed between V1 and V2. Between V1 and V3, there was a statistically significant decrease in the percentage of individuals with abnormal biochemical markers for glucose, potassium, total protein and albumin. The number of patients’ bowel movements remained stable throughout the study with a mean of 1.1 daily bowel movements. Conclusion: The TFF was safe and well tolerated, improving patients’ nutritional status without altering patients’ bowel habits. Introducción: la nutrición enteral es una intervención efectiva para pacientes desnutridos o en riesgo de sufrir desnutrición. Sin embargo, puede desencadenar complicaciones como intolerancia gastrointestinal, hiperglicemia o síndrome de realimentación. Objetivo: investigar los efectos de una fórmula de nutrición enteral por sonda en el estado nutricional y bioquímico, hábitos gastrointestinales y seguridad de los pacientes. Metodología: estudio observacional, prospectivo y multicéntrico. Se incluyeron pacientes = 18 años, desnutridos o en riesgo de desnutrición, tributarios de recibir una fórmula de nutrición enteral hipercalórica, hiperproteica, y rica en fibra y fructooligosacáridos. Los pacientes fueron evaluados durante 8 semanas en 3 visitas (V1, inicial; V2, 4 semanas; V3, 8 semanas). Resultados: entre V1 y V2 se observó un incremento estadísticamente significativo en peso (1, 5 kg), índice de masa corporal (0, 6 kg/m2) e ingesta calórica (59, 7 kcal/día). Entre V1 y V3, existió un descenso en el porcentaje de pacientes con valores anormales de glucosa, potasio, proteína total y albúmina. Los hábitos intestinales se mantuvieron estables durante el estudio (1, 1 deposiciones diarias de media). Conclusión: la fórmula fue segura, tolerada, y mejoró el estado nutricional del paciente sin alterar los hábitos intestinales

Synthesis of the BCDE Molecular Fragment of Azadiradione Mediated by Titanocene(III)

[EN]A practical, short, and diastereoselective synthesis of the azadiradione BCDE fragment from a readily available starting material is described. The key step was the titanocene(III)-promoted tandem cyclization of unsaturated epoxy nitrile

Advanced data acquisition system implementation for the ITER Neutron Diagnostic use case using EPICS and FlexRIO technology on a PXIe platform

In the framework of the ITER Control Breakdown Structure (CBS), Plant System Instrumentation & Control (I&C) defines the hardware and software required to control one or more plant systems [1]. For diagnostics, most of the complex Plant System I&C are to be delivered by ITER Domestic Agencies (DAs). As an example for the DAs, ITER Organization (IO) has developed several use cases for diagnostics Plant System I&C that fully comply with guidelines presented in the Plant Control Design Handbook (PCDH) [2]. One such use case is for neutron diagnostics, specifically the Fission Chamber (FC), which is responsible for delivering time-resolved measurements of neutron source strength and fusion power to aid in assessing the functional performance of ITER [3]. ITER will deploy four Fission Chamber units, each consisting of three individual FC detectors. Two of these detectors contain Uranium 235 for Neutron detection, while a third "dummy" detector will provide gamma and noise detection. The neutron flux from each MFC is measured by the three methods: . Counting Mode: measures the number of individual pulses and their location in the record. Pulse parameters (threshold and width) are user configurable. . Campbelling Mode (Mean Square Voltage): measures the RMS deviation in signal amplitude from its average value. .Current Mode: integrates the signal amplitude over the measurement perio