1,700 research outputs found

    Effects of construction delays on construction project objectives

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    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

    Electroweak phase transition in the presence of hypermagnetic field and the generation of gravitational waves

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    We investigate the effects of a large-scale background hypermagnetic field on the electroweak phase transition. We propose an effective weak angle which varies during the electroweak phase transition and upon its use, show that for a strong enough hypermagnetic field the phase transition occurs in two steps and becomes first-order. We obtain all of the important quantities characterizing the details of the phase transition, including the latent heat, transition temperature and duration. We then explore one of the consequences of this model which is the generation of gravitational waves. We calculate the gravitational wave energy spectrum generated during the first-order electroweak phase transition and find that, for strong enough background hypermagnetic fields, these signals can be detected by the Ultimate-DECIGO interferometer.Comment: 19 pages, 7 figures; v3: more discussions adde

    Vertical velocities from proper motions of red clump giants

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    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

    The Experiences of Family Members of Non-Organ Donors on the Crisis Rising From Patients' Brain Death

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    Background: Brain death crisis as an overwhelming situation can create a critical state for families in which they are unable to make logical decisions for their patients with brain death. Objectives: This study aimed to explore the experiences of family members of patients with brain death, who did not donate their patients’ organs. Methods: A qualitative study was conducted on nine non-donor family members of patients with brain death, selected using the purposeful sampling method. To collect data, deep unstructured interviews were held to reach data saturation. The interviews were transcribed verbatim and analyzed utilizing the phenomenology approach based on the seven-step Colaizzi’s method. Results: The participants of this study explained their situation as ‘an overwhelming situation in families due to patients’ brain death’. Also, the data analysis led to the development of four main themes as follow: ‘overwhelming situation’, ‘perplexity factors’, ‘the sling loops of defect in consent for organ donation’, and ‘compatibility’. Conclusions: The overwhelming effects of the patients’ brain death on the family members and the crisis rising from it influenced the decisions made by family members for organ donation. Therefore, some measures should be taken to cultivate appropriate adaptive behaviors among family members for relieving their sorrow and pain. Moreover, healthcare team members should be informed of the crisis raised from patient’s brain death and help family members make logical decisions with regards to organ donation

    Scintigraphy with 99mTc(V)-DMSA in monitoring patients with inflammatory bowel disease

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    The clinical significance of pentavalent technetium-99m dimercaptosuccinic acid (99mTc(V)-DMSA) scintigraphy in diagnosing inflammatory bowel disease (IBD) has not yet been fully elucidated. The aim of this prospective paper was to study the above. This study included 54 patients, 22 females and 32 males (mean age: 36.68±11.49; range: 18-63 years) with IBD who came to our clinics for follow-up and were examined clinically by colonoscopy and 99mTc(V)-DMSA scintigraphy. On the follow-up studies, five patients (9.25%) relapsed, and 49 (90.74%) remained at a steady condition. There was a good correlation between the scintigraphic results and the clinical and colonoscopy data of the patients (P<0.05). In conclusion, our results indicated that 99mTc(V)DMSA scintigraphy can be complementary to colonoscopy for the diagnostic evaluation of IBD

    The evaluation of base deficit as the predictive agent of mortality in geriatric trauma

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    زمینه و هدف: کمبود باز (Base deficit) به عنوان یک عامل مرتبط با کاهش پرفیوژن نسجی مخفی شناخته شده است، لیکن نقطه بحرانی مؤثر در ایجاد این حالت و مرگ و میر به دنبال تروما تعیین نشده است. در این مطالعه ارزش پیشگویی کننده کمبود باز در مرگ و میر و نقطه برش آن در افراد سالمند مورد بررسی قرار گرفت. روش بررسی: در یک مطالعه تحلیلی - آینده نگر 300 بیمار سالمند (سن بالاتر یا مساوی 65 سال) مبتلا به تروما در مرکز پزشکی الزهراء (س) دانشگاه علوم پزشکی اصفهان مورد بررسی قرار گرفتند. از هر بیمار گازهای خونی آنالیز شده و مقدار کمبود باز محاسبه گردید و عوامل مؤثر در تغییرات کمبود باز مورد ارزیابی قرار گرفت. وضعیت بیماران تا زمان ترخیص و یا مرگ پیگیری شد و عوامل مؤثر در مرگ بیماران نیز مورد بررسی قرار گرفت. جهت تجزیه و تحلیل داده ها از محاسبه رگرسیون استفاده شد. یافته ها: نتایج این مطالعه نشان داد که در افراد سالمند مبتلا به تروما و علائم حیاتی پایدار، کمبود باز تنها عامل پیشگویی کننده مرگ می باشد (01/0
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