Cost Management Practice of Construction Firms and Its Influencing Factors: Lessons from Southwestern Nigeria

The growing need at maintaining steady cost projection of construction projects has been an issue of serious concern to both the clients and the construction practitioners on sites. Also, cost deviation from initial cost plan and cost budget has been prevalent on construction sites and no concerted efforts have been made at addressing this phenomenon. This study therefore examined the factors that are considered to be affecting the cost management practice of construction firms in the southwestern Nigeria and also proffered possible ways of ameliorating the factors. Using survey approach, one hundred copies each of structured questionnaires were distributed to clients, contractors and consultants on construction sites in the study area while 72, 77 and 78 copies were duly filled and returned by the respondents respectively. Relative Importance Index (RII) technique was used for the analysis. The results revealed that poor leadership and in appropriate management, inefficient deployment of resources, excessive wastage of materials on sites, complex payment mechanisms, theft of materials on sites and variation during construction works are the prevailing factors affecting construction cost management practice in the study area. It was concluded that extra focus should be placed on the identified factors with a view to reducing cost of construction, enhancing construction performance and building confidence within the construction industry in the study area

Analysis of the rotational properties of Kuiper belt objects

We use optical data on 10 Kuiper Belt objects (KBOs) to investigate their rotational properties. Of the 10, three (30%) exhibit light variations with amplitude delta_m >= 0.15 mag, and 1 out of 10 (10%) has delta_m >= 0.40 mag, which is in good agreement with previous surveys. These data, in combination with the existing database, are used to discuss the rotational periods, shapes, and densities of Kuiper Belt objects. We find that, in the sampled size range, Kuiper Belt objects have a higher fraction of low amplitude lightcurves and rotate slower than main belt asteroids. The data also show that the rotational properties and the shapes of KBOs depend on size. If we split the database of KBO rotational properties into two size ranges with diameter larger and smaller than 400 km, we find that: (1) the mean lightcurve amplitudes of the two groups are different with 98.5% confidence, (2) the corresponding power-law shape distributions seem to be different, although the existing data are too sparse to render this difference significant, and (3) the two groups occupy different regions on a spin period vs. lightcurve amplitude diagram. These differences are interpreted in the context of KBO collisional evolution.Comment: 15 pages, 14 figures, LaTeX. Astronomical Journal in pres

Taxonomy of asteroid families among the Jupiter Trojans: Comparison between spectroscopic data and the Sloan Digital Sky Survey colors

We present a comparative analysis of the spectral slope and color distributions of Jupiter Trojans, with particular attention to asteroid families. We use a sample of data from the Moving Object Catalogue of the Sloan Digital Sky Survey, together with spectra obtained from several surveys. A first sample of 349 observations, corresponding to 250 Trojan asteroids, were extracted from the Sloan Digital Sky Survey, and we also extracted from the literature a second sample of 91 spectra, corresponding to 71 Trojans. The spectral slopes were computed by means of a least-squares fit to a straight line of the fluxes obtained from the Sloan observations in the first sample, and of the rebinned spectra in the second sample. In both cases the reflectance fluxes/spectra were renormalized to 1 at 6230 $\textrm{\AA}$. We found that the distribution of spectral slopes among Trojan asteroids shows a bimodality. About 2/3 of the objects have reddish slopes compatible with D-type asteroids, while the remaining bodies show less reddish colors compatible with the P-type and C-type classifications. The members of asteroid families also show a bimodal distribution with a very slight predominance of D-type asteroids, but the background is clearly dominated by the D-types. The L4 and L5 swarms show different distributions of spectral slopes, and bimodality is only observed in L4. These differences can be attributed to the asteroid families since the backgraound asteroids show the same slope distribtuions in both swarms. The analysis of individual families indicates that the families in L5 are taxonomically homogeneous, but in L4 they show a mixture of taxonomic types. We discuss a few scenarios that might help to interpret these results.Comment: 20 pages, 15 figures, 2 table

Efficient broadband highly dispersive HfO_2/SiO_2 multilayer mirror for pulse compression in near ultraviolet

We report on design, production and implementation of a highly dispersive broadband dielectric multilayer mirror covering near ultraviolet range from 290 nm to 350 nm. The described mirrors, having 92% spectrally averaged reflectance in the ultraviolet range and ~85 fs of group delay difference, that allow compression to ~7 fs, provide a strong foundation for generation of few-fs pulses in the near ultraviolet

Saponite Dissolution Experiments and Implications for Mars

Recent work suggests that the mineralogical sequence of the Murray formation at Gale crater may have resulted from diagenetic alteration after sedimentation, or deposition in a stratified lake with oxic surface and anoxic bottom waters. Fe-containing clay minerals are common both at Gale crater, and throughout the Noachian-aged terrains on Mars. These clay minerals are primarily ferric (Fe3+), and previous work suggests that these ferric clay minerals may result from alteration of ferrous (Fe2+) smectites that were oxidized after deposition. The detection of trioctahedral smectites at Gale crater by CheMin suggests Fe2+ smectite was also deposited during the early Hesperian. However, due to their sensitivity to oxygen, Fe2+ smectites are difficult to analyze on Earth and very few saponite dissolution rates exist in the literature. To the best of our knowledge, no experiments have measured the dissolution rates of ferrous saponites under oxidizing and reducing conditions. In order to better understand the characteristics of water-rock interaction at Gale crater, particularly the oxidation state, we report our results to date on ongoing syntheses of ferrous and magnesium saponites and dissolution experiments of natural saponite under ambient conditions. Future experiments will include the dissolution of synthetic ferric, ferrous, and magnesium saponites under oxidizing and anoxic conditions at a range of pH values

Values of sexual behaviour in Central and Eastern Europe

Despite the profusion of social cognitive models for the prediction of sexual behaviour, we have only limited knowledge as to the role of individual values in predicting risky sexual activity. This study assessed the relationship between a recently developed value structure and sexual behaviour in the context of rising HIV infection in central and eastern Europe. Five hundred and three respondents (business people, doctors and nurses) from Estonia, Georgia, Hungary, Poland and Russia completed Schwartz’s Portrait Values Questionnaire and reported their condom use, partnership history and record of sexual disease. Results indicated that values had a moderate but consistent relationship with sexual behaviour, with riskier sexual activity reported by those high on Openness to Change, Hedonism and Self-Enhancement. These findings are discussed in the context of the need for culturally sensitive interventions in order to tackle the growing HIV epidemic in this region.This project was supported by a research grant from the Research Support Scheme operated by the Soros Foundation, Prague

Use of viability PCR for detection of live Chlamydia trachomatis in clinical specimens

BackgroundThe current testing approach to diagnose Chlamydia trachomatis (CT) infection relies on nucleic acid amplification tests (NAATs). These tests are highly sensitive, but do not distinguish between active infection and residual bacterial nucleic acid which may remain after resolution of infection, or via cross-contamination. Better methods to assess the viability of CT detected in clinical samples would be useful in determining the relevance of CT detection in a variety of clinical settings. The goal of this study was to test viability PCR (vPCR) as a method to distinguish viable bacteria from non-viable CT.MethodsThe vPCR relies on a propidium monoazide dye (PMAxx), which intercalates into accessible DNA from dead organisms and prevents their detection in a PCR assay for the CT ompA gene. We used digital PCR to quantify absolute genome copy numbers from samples. We validated the vPCR approach using laboratory stocks of CT with known viability. Then, we tested total DNA, viable CT DNA, and culture results from 18 clinical vaginal specimens and 25 rectal clinical specimens, all of which had tested positive by NAAT.ResultsIn laboratory stocks of CT, vPCR using defined ratios of heat-killed to live bacteria tracked closely with expected results. In vaginal clinical specimens, vPCR and total DNA results were correlated, though total DNA genomes outnumbered viable genomes by 2.2–52.6-fold more copies. As expected, vPCR detected more total genomes than culture results. Both vPCR and total DNA correlated with culture results (Spearman correlation R = 0.8425 for total DNA and 0.8056 for vPCR). Ten rectal NAAT positive specimens were negative by total DNA PCR, vPCR, and were negative or inconclusive by culture. Of the 6 rectal specimens that were culture positive, all were total DNA and vPCR positive. vPCR additionally detected viable bacterial DNA in 8 specimens which were NAAT + and culture negative, though levels were very low (mean 1,357 copies/ml)ConclusionsvPCR is a fast and easy method to assess viability in clinical specimens and is more correlated with culture results than total DNA PCR. Inconsistent ratios between total DNA and vPCR results suggest that the amount of dead bacteria varies considerably in clinical specimens. Results from rectal specimens suggest that many NAAT positive specimens do not in fact represent live replicating bacteria, and likely result in significant overuse of unnecessary antibiotics

Stem cell‐derived enteroid cultures as a tool for dissecting host‐parasite interactions in the small intestinal epithelium.

Toxoplasma gondii and Cryptosporidium spp. can cause devastating pathological effects in humans and livestock, and in particular to young or immunocompromised individuals. The current treatment plans for these enteric parasites are limited due to long drug courses, severe side effects, or simply a lack of efficacy. The study of the early interactions between the parasites and the site of infection in the small intestinal epithelium has been thwarted by the lack of accessible, physiologically relevant, and species-specific models. Increasingly, 3D stem cell-derived enteroid models are being refined and developed into sophisticated models of infectious disease. In this review we shall illustrate the use of enteroids to spearhead research into enteric parasitic infections, bridging the gap between cell line cultures and in vivo experiments

MSV3d: database of human MisSense variants mapped to 3D protein structure

The elucidation of the complex relationships linking genotypic and phenotypic variations to protein structure is a major challenge in the post-genomic era. We present MSV3d (Database of human MisSense Variants mapped to 3D protein structure), a new database that contains detailed annotation of missense variants of all human proteins (20 199 proteins). The multi-level characterization includes details of the physico-chemical changes induced by amino acid modification, as well as information related to the conservation of the mutated residue and its position relative to functional features in the available or predicted 3D model. Major releases of the database are automatically generated and updated regularly in line with the dbSNP (database of Single Nucleotide Polymorphism) and SwissVar releases, by exploiting the extensive Décrypthon computational grid resources. The database (http://decrypthon.igbmc.fr/msv3d) is easily accessible through a simple web interface coupled to a powerful query engine and a standard web service. The content is completely or partially downloadable in XML or flat file formats