11,432 research outputs found

    Frequency Shift of Carbon-Nanotube-Based Mass Sensor Using Nonlocal Elasticity Theory

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    The frequency equation of carbon-nanotube-based cantilever sensor with an attached mass is derived analytically using nonlocal elasticity theory. According to the equation, the relationship between the frequency shift of the sensor and the attached mass can be obtained. When the nonlocal effect is not taken into account, the variation of frequency shift with the attached mass on the sensor is compared with the previous study. According to this study, the result shows that the frequency shift of the sensor increases with increasing the attached mass. When the attached mass is small compared with that of the sensor, the nonlocal effect is obvious and increasing nonlocal parameter decreases the frequency shift of the sensor. In addition, when the location of the attached mass is closer to the free end, the frequency shift is more significant and that makes the sensor reveal more sensitive. When the attached mass is small, a high sensitivity is obtained

    A regulatory role for repeated decoy transcription factor binding sites in target gene expression

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    Repetitive stretches of DNA that contain transcription factor (TF) binding sites can act as decoys that sequester TFs. This study shows that these decoy sites can have important indirect effects on transcriptional regulation by altering the dose–response between a TF and its target promoter

    Antibody-Dependent Enhancement (ADE) of influenza infection and its possible role in the pathogenesis of influenza

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    Poster Presentations: P05postprintThe International Symposium on 'Surveillance and Discovery in Respiratory and Other Emerging Infections', Phnom Penh, Cambodia, 29-31 May 2011

    Antibody-Dependent Enhancement (ADE) of infection and its possible role in the pathogenesis of influenza

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    Poster Presentationpublished_or_final_versionAnnual Scientific Meeting of the Institut Pasteur International Network, Hong Kong, China, 22-23 November 2010. In BMC Proceedings, 2011, v. 5, suppl. 1, p. 6

    Judgement and supply chain dynamics

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    Forecasting demand at the individual stock-keeping-unit (SKU) level often necessitates the use of statistical methods, such as exponential smoothing. In some organizations, however, statistical forecasts will be subject to judgemental adjustments by managers. Although a number of empirical and ‘laboratory’ studies have been performed in this area, no formal OR modelling has been conducted to offer insights into the impact such adjustments may have on supply chain performance and the potential development of mitigation mechanisms. This is because of the associated dynamic complexity and the situation-specific nature of the problem at hand. In conjunction with appropriate stock control rules, demand forecasts help decide how much to order. It is a common practice that replenishment orders may also be subject to judgemental intervention, adding further to the dynamic system complexity and interdependence. The system dynamics (SD) modelling method can help advance knowledge in this area, where mathematical modelling cannot accommodate the associated complexity. This study, which constitutes part of a UK government funded (EPSRC) project, uses SD models to evaluate the effects of forecasting and ordering adjustments for a wide set of scenarios involving: three different inventory policies; seven different (combinations of) points of intervention; and four different (combinations of) types of judgmental intervention (optimistic and pessimistic). The results enable insights to be gained into the performance of the entire supply chain. An agenda for further research concludes the paper

    A titanium dioxide/nitrogen-doped graphene quantum dot nanocomposite to mitigate cytotoxicity: synthesis, characterisation, and cell viability evaluation

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    Titanium dioxide nanoparticles (TiO2 NPs) have attracted tremendous interest owing to their unique physicochemical properties. However, the cytotoxic effect of TiO2 NPs remains an obstacle for their wide-scale applications, particularly in drug delivery systems and cancer therapies. In this study, the more biocompatible nitrogen-doped graphene quantum dots (N-GQDs) were successfully incorporated onto the surface of the TiO2 NPs resulting in a N-GQDs/TiO2 nanocomposites (NCs). The effects of the nanocomposite on the viability of the breast cancer cell line (MDA-MB-231) was evaluated. The N-GQDs and N-GQDs/TiO2 NCs were synthesised using a one- and two-pot hydrothermal method, respectively while the TiO2 NPs were fabricated using microwave-assisted synthesis in the aqueous phase. The synthesised compounds were characterised using Fourier transform infrared (FTIR) spectroscopy, high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM) and UV-visible spectrophotometry. The cell viability of the MDA-MB-231 cell line was determined using a CellTiter 96® AQueous One Solution Cell Proliferation (MTS) assay. The obtained results indicated that a monodispersed solution of N-GQDs with particle size 4.40 ± 1.5 nm emitted intense blue luminescence in aqueous media. The HRTEM images clearly showed that the TiO2 particles (11.46 ± 2.8 nm) are square shaped. Meanwhile, TiO2 particles were located on the 2D graphene nanosheet surface in N-GQDs/TiO2 NCs (9.16 ± 2.4 nm). N-GQDs and N-GQDs/TiO2 NCs were not toxic to the breast cancer cells at 0.1 mg mL−1 and below. At higher concentrations (0.5 and 1 mg mL−1), the nanocomposite was significantly less cytotoxic compared to the pristine TiO2. In conclusion, this nanocomposite with reduced cytotoxicity warrants further exploration as a new TiO2-based nanomaterial for biomedical applications, especially as an anti-cancer strategy

    EL2 deep donor state in semi-insulating GaAs revealed by frequency dependent positron mobility measurements

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    Positron mobility measurements carried out on semi-insulating GaAs, using the Doppler shift in annihilation radiation technique, show a sharp transition from a high mobility value ∼120 cm2 V-1 s-1 to a lower value ∼45 V-1 s-1 just below room temperature. The temperature of the transition is found to be dependent on the frequency of the applied AC bias. We show that this effect is an artifact due to the thermal ionization of the EL2 deep donor state, which in its ionized state forms a positive space charge that causes the positron to experience large electric fields. This observation suggests a new positron annihilation-based deep-level transient technique applicable to semi-insulating materials. © 1994 The American Physical Society.published_or_final_versio

    Late widespread skeletal metastases from myxoid liposarcoma detected by MRI only

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    Background Myxoid liposarcoma is the second most commonly occurring sub-type of liposarcomas. In contrast to other soft tissue sarcomas, it is known to have a tendency to spread toward extrapulmonary sites, such as soft tissues, retroperitoneum, and the peritoneal surface. Bony spread, however, is not as common. Case presentation We report an unusual case of diffuse skeletal metastases from myxoid liposarcoma occurring 13 years after treatment of the primary tumour in the left lower limb. The skeletal spread of the disease was demonstrated on MRI only after other imaging modalities (plain radiography, CT and TC99 bone scans) had failed to detect these metastases. Conclusion MRI is an extremely sensitive and specific screening tool in the detection of skeletal involvement in these types of sarcomas, and therefore, should be a part of the staging proces

    Rupture of the profunda femoris artery in a patient with alcoholic liver disease: a case report

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    Introduction: Profunda femoris artery aneurysms are rare and often present with rupture. However, to the best of our knowledge, rupture of a non-aneurismal profunda femoris artery has never been reported before. Case presentation: We report the case of a 31-year-old Caucasian man with alcoholic liver disease who presented with rupture of the profunda femoris artery following blunt trauma which was treated by endovascular embolization. Conclusion: Coagulopathy secondary to alcoholic liver disease is a major contributory factor and a high index of suspicion of vascular injury must be attached to such patients following blunt trauma. Although there have no previous documented cases, treatment by endovascular embolization appears to be effective and safe
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