972 research outputs found
Vertical velocities from proper motions of red clump giants
We derive the vertical velocities of disk stars in the range of
Galactocentric radii of R=5-16 kpc within 2 kpc in height from the Galactic
plane. This kinematic information is connected to dynamical aspects in the
formation and evolution of the Milky Way, such as the passage of satellites and
vertical resonance and determines whether the warp is a long-lived or a
transient feature.
We used the proper motions of the PPMXL survey, correcting of systematic
errors with the reference of quasars. From the color-magnitude diagram K versus
(J-K) we selected the standard candles corresponding to red clump giants and
used the information of their proper motions to build a map of the vertical
motions of our Galaxy. We derived the kinematics of the warp both analytically
and through a particle simulation to fit these data. Complementarily, we also
carried out the same analysis with red clump giants spectroscopically selected
with APOGEE data, and we predict the improvements in accuracy that will be
reached with future Gaia data.
A simple model of warp with the height of the disk z_w(R,phi)=gamma (R-R_sun)
sin(phi-phi_w) fits the vertical motions if d(gamma)/dt/gamma=-34+/-17
Gyr^{-1}; the contribution to d(gamma)/dt comes from the southern warp and is
negligible in the north. The vertical motion in the warp apparently indicates
that the main S-shaped structure of the warp is a long-lived feature, whereas
the perturbation that produces an irregularity in the southern part is most
likely a transient phenomenon. With the use of the Gaia end-of-mission products
together with spectroscopically classified red clump giants, the precision in
vertical motions can be increased by an order of magnitude at least.Comment: Accepted for publication in A&A. arXiv admin note: text overlap with
arXiv:1402.355
Effects of construction delays on construction project objectives
Delays can be defined as the late completion of works as compared to the planned schedule on the contract. Delays can be avoided or minimized only when their causes are identified. When delay occurred in to our project, it will have adverse consequences on project objectives in terms of time, cost and quality. The aim of the study reported in this paper was to identify the effects of delays that could threat project objectives in construction projects. A comprehensive literature review from various sources through books, conference proceedings, the internet, and civil engineering journals was made to carry out the study. According to delay categories that were contractor related, client related, consultant related, labor related and external related, the results of this study identified the six major effects of delay that were time overrun, cost overrun, dispute, arbitration, total abandonment, and litigation. The study also revealed that time and cost overruns were the frequent effects of delay. It is hoped that this study will become the foundation of further research in the area of project delays and mitigation measures
Developing Mitigation Measures for Delays in Building Construction Projects: A Case Study in the City of Esfahan
Developing mitigation measures are to avoid or minimize the magnitude of adverse consequences of delay causes that could threat the project objectives in terms of time, cost and quality. It is also vital to be aware of mitigation measures within the construction industry. The aim of the study reported in this paper is to develop mitigation measures for delays in building construction projects in the city of Isfahan, Iran. A questionnaire survey was used to carry out the study which was filled out by professional parties such as clients, contractors, architects, project managers, consultants and developers in the construction industry. Feedbacks from respondents gave variety of measures for each cause of delay to mitigate the adverse and disruptive consequences of delay causes in building construction projects in Isfahan. Time and cost overrun were the common negative effects of delays in building construction projects in Isfahan. The study has found that twenty one significant mitigation measures based on the different points of view from respondents of the questionnaire survey, in order to avoid or minimize the causes of delays in building construction projects in Isfahan, it has been proposed that the top six most effective mitigation measures of avoiding or minimizing these delays were further elaborated. This include: considering the clients views while providing designs, setting the project budget according to proper and accurate estimations, efficient and effective project management among the parties in the project, proper selection of competent and capable contractors appropriate for the project, appropriate delegating of project parties regarding to their specialties and skills and also having sufficient knowledge of project environment and project parties before the project starts. It is hope that this finding will be able to address issues and problems of delays in building construction projects in general in Iran
Effect of TiO2-ZnO/GAC on by-product distribution of CVOCs decomposition in a NTP-assisted catalysis system
In this study, the catalytic effect of TiO2-ZnO/GAC coupled with non-thermal plasma was investigated on the byproducts distribution of decomposition of chlorinated VOCs in gas streams. The effect of specific input energy, and initial gas composition was examined in a corona discharge reactor energized by a high frequency pulsed power supply. Detected by-products for catalytic NTP at 750 J L-1 included CO, CO2, Cl2, trichloroacetaldehyde, as well as trichlorobenzaldehyde with chloroform feeding, while they were dominated by CO, CO2, and lower abundance of trichlorobenzaldehyde and Cl2 with chlorobenzene introduction. Some of the by-products such as O3, NO, NO2, and COCl2 disappeared totally over TiO2-ZnO/GAC. Furthermore, the amount of heavy products such as trichlorobenzaldehyde decreased significantly in favor of small molecules such as CO, CO2, and Cl2 with the hybrid process. The selectivity towards COx soared up to 77 over the catalyst at 750 J L-1 and 100 ppm of chlorobenzene. © by Farshid Ghorbani-Shahna 2015
Universal standards for the concept of trust in online dispute resolution systems in e-commerce disputes
Is the Molecular Berry Phase an Artifact of the Born-Oppenheimer Approximation?
We demonstrate that the molecular Berry phase and the corresponding nonanalyticity in the electronic Born-Oppenheimer wave function is, in general, not a true topological feature of the exact solution of the full electron-nuclear Schrodinger equation. For a numerically exactly solvable model we show that a nonanalyticity, and the associated geometric phase, only appear in the limit of infinite nuclear mass, while a perfectly smooth behavior is found for any finite nuclear mass.open
Prognostic factors for esophageal squamous cell Carcinoma-A Population-Based study in Golestan province, Iran, a high incidence area
Golestan Province in northern Iran is an area with a high incidence of esophageal squamous cell carcinoma (ESCC). We aimed to investigate prognostic factors for ESCC and survival of cases in Golestan, on which little data were available. We followed-up 426 ESCC cases participating in a population-based case-control study. Data were analyzed using the Kaplan-Meier method and the Cox proportional hazard models. Median survival was 7 months. Age at diagnosis was inversely associated with survival, but the association was disappeared with adjustment for treatment. Residing in urban areas (hazard ratio, HR = 0.70; 95 CI 0.54-0.90) and being of non-Turkmen ethnic groups (HR = 0.76; 95 CI 0.61-0.96) were associated with better prognosis. In contrast to other types of tobacco use, nass (a smokeless tobacco product) chewing was associated with a slightly poorer prognosis even in models adjusted for other factors including stage of disease and treatment (HR = 1.38; 95 CI 0.99-1.92). Opium use was associated with poorer prognosis in crude analyses but not in adjusted models. Almost all of potentially curative treatments were associated with longer survival. Prognosis of ESCC in Golestan is very poor. Easier access to treatment facilities may improve the prognosis of ESCC in Golestan. The observed association between nass chewing and poorer prognosis needs further investigations; this association may suggest a possible role for ingestion of nass constituents in prognosis of ESCC. © 2011 Aghcheli et al
The effect of tactile-kinesthetic stimulation on growth indices of healthy neonates
Abstract
Therapeutic touch is emphasized by healthcare professionals for improvement of neonates' growth and development. However, inconsistencies exist regarding effects and methods of massage in neonates. The purpose of this clinical trial is to assess and comprise intervention and control groups regarding the effects of tactile-kinesthetic stimulation (TKS) by mothers on growth indices of healthy term neonates. Sixty healthy term neonates were randomly assigned into intervention and control groups. Mothers of neonates in the experimental group were trained to perform TKS for their newborns at home before feeding for at least 28 consecutive days, two times a day, and 15 min each time. Neonates in the control group were not required to receive this intervention. The neonates’ growth indices were measured within 24 h after birth, and then at days 14 and 28. During the study and the three consecutive measurements, no significant difference was found between the mean weights, heights, and head circumferences of the neonates in the two groups (p > 0.05).
Keywords:
Tactile-kinesthetic stimulation Growth indices Neonates
Mother's touc
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