13,912 research outputs found

    On site challenges for the construction of 16-storey condominium: as observed by a young civil engineering technologist

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    The difference between an engineer and an engineering technologist is that, an engineer would mainly focus and produce structural designs based on engineering calculations, while the job of an engineering technologist is to execute the design in the real working environment by adopting flexible and critical technical ideas on-site. The challenges can be divided into two categories, namely design challenges faced by an engineer and the construction challenges faced by an engineering technologist. Thus, the job scope of an engineering technologist is relatively wider when compared to that of an engineer, as the engineering technologist would be dealing with the consultant, contractors and suppliers on site, while handling the in situ construction challenges. This requires basic understanding of engineering principles and technology, critical thinking and problem-solving skills, modern tools competency in software applications, designs and construction calculations, as well as communication and leadership skills all rolled into one. I have recorded my experience as a junior civil engineering technologist engaged in the construction works of a 16-storey condominium at Langkawi, Kedah. Included in the descriptions are in situ technical problems encountered, potentially unsafe working conditions, foundations, scheduling and housekeeping on site, among others. I hope that the information shared in this entry would make a good introduction and induction for juniors entering the work site, where my personal undertakings could serve as a guide and reminder for them

    The Mass-Loss Return From Evolved Stars to The Large Magellanic Cloud VI: Luminosities and Mass-Loss Rates on Population Scales

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    We present results from the first application of the Grid of Red Supergiant and Asymptotic Giant Branch ModelS (GRAMS) model grid to the entire evolved stellar population of the Large Magellanic Cloud (LMC). GRAMS is a pre-computed grid of 80,843 radiative transfer (RT) models of evolved stars and circumstellar dust shells composed of either silicate or carbonaceous dust. We fit GRAMS models to ~30,000 Asymptotic Giant Branch (AGB) and Red Supergiant (RSG) stars in the LMC, using 12 bands of photometry from the optical to the mid-infrared. Our published dataset consists of thousands of evolved stars with individually determined evolutionary parameters such as luminosity and mass-loss rate. The GRAMS grid has a greater than 80% accuracy rate discriminating between Oxygen- and Carbon-rich chemistry. The global dust injection rate to the interstellar medium (ISM) of the LMC from RSGs and AGB stars is on the order of 1.5x10^(-5) solar masses/yr, equivalent to a total mass injection rate (including the gas) into the ISM of ~5x10^(-3) solar masses/yr. Carbon stars inject two and a half times as much dust into the ISM as do O-rich AGB stars, but the same amount of mass. We determine a bolometric correction factor for C-rich AGB stars in the K band as a function of J - K color, BC(K) = -0.40(J-K)^2 + 1.83(J-K) + 1.29. We determine several IR color proxies for the dust mass-loss rate (MLR) from C-rich AGB stars, such as log (MLR) = (-18.90)/((K-[8.0])+3.37)-5.93. We find that a larger fraction of AGB stars exhibiting the `long-secondary period' phenomenon are O-rich than stars dominated by radial pulsations, and AGB stars without detectable mass-loss do not appear on either the first-overtone or fundamental-mode pulsation sequences.Comment: 19 pages, 19 figure

    Distinct Salivary Biomarker Profile in Chronic Periodontitis

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    poster abstractBackground: Saliva has potential to diagnose chronic periodontitis (CP). Changes in tissue-expression of pattern-recognition-receptors (PRRs), which recognize periodontal-pathogens, correlate with CP. It follows that PRRs-expression in nucleated-cells (NCs) shed in saliva and soluble-PRRs may differentiate CP from health. Additionally, cytokines in gingival cervical fluid (GCF) correlate with worsening CP, which may be reflected in saliva. One significant test for biomarkers is changes in response to treatment. Objectives: Comparison of CP salivary-biomarkers profile with health and to study treatment effects of scaling and root planning (SRP). Methods: Unstimulated whole saliva (UWS) collection and recording of routine clinical periodontal parameters was done for two groups (n=16): healthy (H) (minimal clinical loss of attachment (CAL) and clinical inflammation) and CP (≥30% sites with ≥4mm CAL). UWS was collected at 3 different time points: before, 1-week and 6-weeks after SRP from the CP group. NCs and clarified saliva (CS) were separated from UWS. Messenger RNA was extracted from NCs and TLR-2 expression was quantitated through real-time-PCR. CS depleted of immunoglobulin and amylase to prevent large molecule interferences and diluted to 1 μg/ml of salivary-protein in PBS, normalize for variations in liquid volume, was used to quantify biomarkers through ELISA. Statistical significance between H- and CP-groups biomarkers was determined through Mann-Whitney ‘U' test and one tailed paired ‘t' test. Results: Statistically significant differences were noted for clinical profiles of H- and CP-groups and for changes after SRP within CP-group. Salivary sTLR-2, IL-17 and IL-10, were significantly higher, and sCD14, IL-6, IL-4 and TLR-2 mRNA were significantly lower in H compared to CP. In CP, salivary sTLR-2 and IL10 increased significantly at 1- and 6-weeks after SRP, whilst IL-4 decreased significantly at 6-weeks. Conclusions: Salivary biomarkers profiles are distinct between health and CP as well as before and after SRP treatment. sTLR-2, IL-10 and IL-4 may serve as short-term biomarkers for monitoring response to SRP. sCD14, TLR2-mRNA and other cytokines need exploration as long-term response biomarkers. Depletion of amylase and immunoglobulin, and normalization for total salivary protein may be important in biomarkers quantification

    Linear and nonlinear optical spectroscopy of a strongly-coupled microdisk-quantum dot system

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    A fiber taper waveguide is used to perform direct optical spectroscopy of a microdisk-quantum-dot system, exciting the system through the photonic (light) channel rather than the excitonic (matter) channel. Strong coupling, the regime of coherent quantum interactions, is demonstrated through observation of vacuum Rabi splitting in the transmitted and reflected signals from the cavity. The fiber coupling method also allows the examination of the system's steady-state nonlinear properties, where saturation of the cavity-QD response is observed for less than one intracavity photon.Comment: adjusted references, added minor clarification

    Tunable coupling in circuit quantum electrodynamics with a superconducting V-system

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    Recent progress in superconducting qubits has demonstrated the potential of these devices for the future of quantum information processing. One desirable feature for quantum computing is independent control of qubit interactions as well as qubit energies. We demonstrate a new type of superconducting charge qubit that has a V-shaped energy spectrum and uses quantum interference to provide independent control over the qubit energy and dipole coupling to a superconducting cavity. We demonstrate dynamic access to the strong coupling regime by tuning the coupling strength from less than 200 kHz to more than 40 MHz. This tunable coupling can be used to protect the qubit from cavity-induced relaxation and avoid unwanted qubit-qubit interactions in a multi-qubit system.Comment: 5 pages, 4 figure

    Fracture Toughness of Metal Castings

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    CO J = 2 - 1 Emission from Evolved Stars in the Galactic Bulge

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    We observe a sample of 8 evolved stars in the Galactic Bulge in the CO J = 2 - 1 line using the Submillimeter Array (SMA) with angular resolution of 1 - 4 arcseconds. These stars have been detected previously at infrared wavelengths, and several of them have OH maser emission. We detect CO J = 2 - 1 emission from three of the sources in the sample: OH 359.943 +0.260, [SLO2003] A12, and [SLO2003] A51. We do not detect the remaining 5 stars in the sample because of heavy contamination from the galactic foreground CO emission. Combining CO data with observations at infrared wavelengths constraining dust mass loss from these stars, we determine the gas-to-dust ratios of the Galactic Bulge stars for which CO emission is detected. For OH 359.943 +0.260, we determine a gas mass-loss rate of 7.9 (+/- 2.2) x 10^-5 M_Sun/year and a gas-to-dust ratio of 310 (+/- 89). For [SLO2003] A12, we find a gas mass-loss rate of 5.4 (+/- 2.8) x 10^-5 M_Sun/year and a gas-to-dust ratio of 220 (+/- 110). For [SLO2003] A51, we find a gas mass-loss rate of 3.4 (+/- 3.0) x 10^-5 M_Sun/year and a gas-to-dust ratio of 160 (+/- 140), reflecting the low quality of our tentative detection of the CO J = 2 - 1 emission from A51. We find the CO J = 2 - 1 detections of OH/IR stars in the Galactic Bulge require lower average CO J = 2 - 1 backgrounds.Comment: 40 pages, 16 figures, appeared in the 1 March 2013 issue of the Astrophysical Journa
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