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

Effects of ADHD on writing composition product and process in school-age students

Objective: This study examined the relationship between ADHD and writing performance. Method: Students in Grades 3 to 7, 84 with ADHD and 135 age and gender-matched controls completed a writing task (including process logs), and measures of, working memory and attention. Results: Students with ADHD wrote texts of similar length but with poorer structure, coherence and ideation. 6.7% of the variance in writing quality was explained by whether or not the student had an ADHD diagnosis, after control for IQ and age-within-year, with students with ADHD producing text that was less coherent, well structured, and ideationally rich and to spend less time thinking about and reviewing their text. Half of the effect on text quality could be attributed to working memory and sustained attention effects. Conclusions: ADHD has some effect on writing performance which can, in part, be explained by working memory and attentional deficits

Prólogos de ida y vuelta: Juan de Piña, Alonso de Castillo Solórzano, Francisco de Quintana, Juan Pérez de Montalbán y María de Zayas en el campo literario de Lope de Vega

This paper reviews the dialogue and controversies between the paratexts of a corpus of collections of short novels –and romances– published from 1624 to 1637: Novelas ejemplares y prodigiosas historias (1624) and Varias fortunas (1627) by Juan de Piña; La desdicha en la constancia (1624) and El cuerdo amante (1628) by Miguel Moreno; Sucesos y prodigios de amor (1624) by Juan Pérez de Montalbán; Tardes entretenidas (1625), Jornadas alegres (1626), Tiempo de regocijo (1627), Escarmientos de amor moralizados (1628), Lisardo enamorado (1629) and Huerta de Valencia (1629) by Alonso de Castillo Solórzano; Experiencias de amor y fortuna (1626) and Historia de Hipólito y Aminta (1627) by Francisco de Quintana; and Novelas amorosas y ejemplares (1637) by María de Zayas. It focuses upon the active literary field around Lope de Vega, on the collaborations of the printers Juan González and Luis Sánchez with de bookseller Alonso Pérez and, over all, on the “Prólogo al que leyere” and the “Prólogo de un desapasionado” in the Zayas’s volume. After proposing a writing date for the first one (1626), it is shown that the author of the second foreword (c. 1635-1637) was Castillo Solórzano.El presente artículo pasa revista al diálogo y las controversias entre los paratextos de un corpus de colecciones de relatos –y de novelas largas– publicadas desde 1624 a 1637: Novelas ejemplares y prodigiosas historias (1624) y Varias fortunas (1627) de Juan de Piña; La desdicha en la constancia (1624) y El cuerdo amante (1628) de Miguel Moreno; Sucesos y prodigios de amor (1624) de Juan Pérez de Montalbán; Tardes entretenidas (1625), Jornadas alegres (1626), Tiempo de regocijo (1627), Escarmientos de amor moralizados (1628), Lisardo enamorado (1629) y Huerta de Valencia (1629) de Alonso de Castillo Solórzano; Experiencias de amor y fortuna (1626) e Historia de Hipólito y Aminta (1627) de Francisco de Quintana; y Novelas amorosas y ejemplares (1637) de María de Zayas. Se hace hincapié en el activo campo literario alrededor de Lope de Vega, en las colaboraciones de los impresores Juan González y Luis Sánchez con el librero Alonso Pérez y, sobre todo, en el “Prólogo al que leyere” y el “Prólogo de un desapasionado” del volumen de Zayas. Luego de proponer una fecha de redacción para el primero (1626), se evidencia que el autor del segundo (c. 1635-1637) fue Castillo Solórzano

Parallel-in-time quantum simulation via Page and Wootters quantum time

In the past few decades, researchers have created a veritable zoo of quantum algorithm by drawing inspiration from classical computing, information theory, and even from physical phenomena. Here we present quantum algorithms for parallel-in-time simulations that are inspired by the Page and Wooters formalism. In this framework, and thus in our algorithms, the classical time-variable of quantum mechanics is promoted to the quantum realm by introducing a Hilbert space of "clock" qubits which are then entangled with the "system" qubits. We show that our algorithms can compute temporal properties over $N$ different times of many-body systems by only using $\log(N)$ clock qubits. As such, we achieve an exponential trade-off between time and spatial complexities. In addition, we rigorously prove that the entanglement created between the system qubits and the clock qubits has operational meaning, as it encodes valuable information about the system's dynamics. We also provide a circuit depth estimation of all the protocols, showing an exponential advantage in computation times over traditional sequential in time algorithms. In particular, for the case when the dynamics are determined by the Aubry-Andre model, we present a hybrid method for which our algorithms have a depth that only scales as $\mathcal{O}(\log(N)n)$. As a by product we can relate the previous schemes to the problem of equilibration of an isolated quantum system, thus indicating that our framework enable a new dimension for studying dynamical properties of many-body systems.Comment: 19+15 pages, 18+1 figure

Detection of anomalous microwave emission in the Perseus molecular cloud with the COSMOSOMAS experiment

We present direct evidence for anomalous microwave emission in the Perseus molecular cloud, which shows a clear rising spectrum from 11 to 17 GHz in the data of the COSMOSOMAS experiment. By extending the frequency coverage using WMAP maps convolved with the COSMOSOMAS scanning pattern we reveal a peak flux density of 42 (+/-) 4 Jy at 22 GHz integrated over an extended area of 1.65 x 1.0 deg centered on RA = 55.4 (+/-) 0.1 deg and Dec = 31.8 (+/-) 0.1 deg (J2000). The flux density that we measure at this frequency is nearly an order of magnitude higher than can be explained in terms of normal galactic emission processes (synchrotron, free-free and thermal dust). An extended IRAS dust feature G159.6-18.5 is found near this position and no bright unresolved source which could be an ultracompact HII region or gigahertz peaked source could be found. An adequate fit for the spectral density distribution can be achieved from 10 to 50 GHz by including a very significant contribution from electric dipole emission from small spinning dust grains.Comment: 5 pages, 2 postscript figures, accepted ApJ Let

CRISPR/Cas9 facilitates rapid generation of constitutive forms of transcription factors in Aspergillus niger through specific on-site genomic mutations resulting in increased saccharification of plant biomass

The CRISPR/Cas9 system has been successfully applied for gene editing in filamentous fungi. Previous studies reported that single stranded oligonucleotides can be used as repair templates to induce point mutations in some filamentous fungi belonging to genus Aspergillus. In Aspergillus niger, extensive research has been performed on regulation of plant biomass degradation, addressing transcription factors such as XlnR or GaaR, involved in (hemi-)cellulose and pectin utilization, respectively. Single nucleotide mutations leading to constitutively active forms of XlnR and GaaR have been previously reported. However, the mutations were performed by the introduction of versions obtained through site-directed or UV-mutagenesis into the genome. Here we report a more time- and cost-efficient approach to obtaining constitutively active versions by application of the CRISPR/Cas9 system to generate the desired mutation on-site in the A. niger genome. This was also achieved using only 60-mer single stranded oligonucleotides, shorter than the previously reported 90-mer strands. In this study, we show that CRISPR/Cas9 can also be used to efficiently change functional properties of the proteins encoded by the target gene by on-site genomic mutations in A. niger. The obtained strains with constitutively active XlnR and GaaR versions resulted in increased production of plant biomass degrading enzymes and improved release of D-xylose and L-arabinose from wheat bran, and D-galacturonic acid from sugar beet pulp.Peer reviewe

Novel ion-doped mesoporous glasses for bone tissue engineering: Study of their structural characteristics influenced by the presence of phosphorous oxide

Ion-doped binary SiO2-CaO and ternary SiO2-CaO-P2O5 mesoporous bioactive glasses were synthesized and characterized to evaluate the influence of P2O5 in the glass network structure. Strontium, copper and cobalt oxides in a proportion of 0.8 mol% were selected as dopants because the osteogenic and angiogenic properties reported for these elements. Although the four glass compositions investigated presented analogous textural properties, TEM analysis revealed that the structure of those containing P2O5 exhibited an increased ordered mesoporosity. Furthermore, 29Si NMR revealed that the incorporation of P2O5 increased the network connectivity and that this compound captured the Sr2 +, Cu2 + and Co2 + ions preventing them to behave as modifiers of the silica network. In addition, 31P NMR results revealed that the nature of the cation directly influences the characteristics of the phosphate clusters. In this study, we have proven that phosphorous oxide entraps doping-metallic ions, granting these glasses with a greater mesopores order