A size-dependent functionally graded sinusoidal plate model based on a modified couple stress theory

A size-dependent model for bending and free vibration of functionally graded plate is developed based on the modified couple stress theory and sinusoidal shear deformation theory. In the former theory, the small scale effect is taken into consideration, while the effect of shear deformation is accounted for in the latter theory. The equations of motion and boundary conditions are derived from Hamilton’s principle. Analytical solutions for the bending and vibration problems of simply supported plates are obtained. Numerical examples are presented to illustrate the influences of small scale on the responses of functionally graded microplates. The results indicate that the inclusion of small scale effects results in an increase in plate stiffness, and consequently, leads to a reduction of deflection and an increase in frequency. Such small scale effects are significant when the plate thickness is small, but become negligible with increasing plate thickness

A nonlocal sinusoidal shear deformation beam theory with application to bending, buckling, and vibration of nanobeams

This paper presents a nonlocal sinusoidal shear deformation beam theory for the bending, buckling, and vibration of nanobeams. The present model is capable of capturing both small scale effect and transverse shear deformation effects of nanobeams, and does not require shear correction factors. Based on the nonlocal differential constitutive relations of Eringen, the equations of motion as well as the boundary conditions of the beam are derived using Hamilton’s principle. Analytical solutions for the deflection, buckling load, and natural frequency are presented for a simply supported beam, and the obtained results are compared with those predicted by the nonlocal Timoshenko beam theory. The comparison firmly establishes that the present beam theory can accurately predict the bending, buckling, and vibration responses of short nanobeams where the small scale and transverse shear deformation effects are significant

Thermal transient flow rate sensor for high temperature liquid metal cooled nuclear reactor

In nuclear power plants and accelerator driven system (ADS) for nuclear waste treatment, it is important to monitor the coolant flow rate in the reactor core and pipe-line. In such a strong irradiation, high pressure and temperature environment, no accurate local flow measurement technique is readily available. Electromagnetic (EM) flow meter is popular in low temperature application as it is a non-intrusive technology. However, additional voltage will be produced due to temperature, flow, pressure, the chemical properties of the liquid metal and surface condition of the steel walls. In addition, the non-definite wetting behavior of liquid lead-bismuth to the electrically conducting structure material can lead to incorrect readings even during one measurement day. As the temperature measurement technique is well developed for high temperature applications, one alternative flow rate measurement technique is proposed here based on correlation velocity measurement using temperature sensors. The impulse response function (IRF) will be used instead of the cross-correlation function in the time delay estimation. The IRF method shows a more accurate estimation of the transit time, which allows extremely low velocities (down to 2 cm/sec) to be detected. In this research work, the faster thermal diffusion effect in low Prandtl number liquid metal will be considered for the better delay time estimation. The proposed research will be completed in two years, and in specific, the PIs plan to fulfill the research missions by performing the following activities:1. Review the related literature on correlation velocity measurement technique using temperature noise in the flow field;2. Design and construct a correlation velocity measurement device with a possibility of changing the distances between the two temperature sensors;3. Develop a signal processing and data reduction scheme and implement it to a LabVIEW data acquisition system;4. Perform experiments with different sensor distances and various Reynoldsnumbers in several different water temperatures in single-phase water flows.Experimental results will be compared to a Pitot tube or hot-wire anemometry;5. Evaluate the measurement device in the by-pass system of TC-1.6. Design a circuit board for sensor integration

Star-galaxy separation by far-infrared color-color diagrams for the AKARI FIS All-Sky Survey (Bright Source Catalogue Version beta-1)

To separate stars and galaxies in the far infrared AKARI All-Sky Survey data, we have selected a sample with the complete color information available in the low extinction regions of the sky and constructed color-color plots for these data. We looked for the method to separate stars and galaxies using the color information. We performed an extensive search for the counterparts of these selected All-Sky Survey sources in the NED and SIMBAD databases. Among 5176 objects, we found 4272 galaxies, 382 other extragalactic objects, 349 Milky Way stars, 50 other Galactic objects, and 101 sources detected before in various wavelengths but of an unknown origin. 22 sources were left unidentified. Then, we checked colors of stars and galaxies in the far-infrared flux-color and color-color plots. In the resulting diagrams, stars form two clearly separated clouds. One of them is easy to be distinguished from galaxies and allows for a simple method of excluding a large part of stars using the far-infrared data. The other smaller branch, overplotting galaxies, consists of stars known to have an infrared excess, like Vega and some fainter stars discovered by IRAS or 2MASS. The color properties of these objects in any case make them very difficult to distinguish from galaxies. We conclude that the FIR color-color diagrams allow for a high-quality star-galaxy separation. With the proposed simple method we can select more that 95 % of galaxies rejecting at least 80 % of stars.Comment: 20 pages, 41 figures, "Astronomy & Astrophysics", accepted, to appear in the AKARI special issu

‘It’s too late’. Is it really? Considerations for amblyopia treatment in older children

In recent years, media coverage has demonstrated instances in which families of children aged 7 and older, newly diagnosed with strabismic and/or anisometropic amblyopia through community eyecare services, were told it was ‘too late’ for their child to effectively respond to conventional amblyopia treatment (occlusion or atropine penalisation). Formal guidance pertaining to binocular vision anomalies from eyecare professional bodies does not specifically make reference to a child’s age, beyond stating the importance of early diagnosis and treatment of strabismus/amblyopia. However, there have been many changes in the way we view the recovery period for amblyopia, and it is well demonstrated both within literature and clinical practice that conventional treatment can improve amblyopic eye visual acuity in children beyond the age of 7 years. The occurrence of these media described cases within the community eyecare sphere would suggest it is worthwhile revisiting the literature on the subject of amblyopia treatment in older children (aged 7+ years), to address misconceptions and place in the spotlight current considerations facing clinicians when treating newly diagnosed amblyopia within this age group. This perspective review provides an evidence-based update covering the various considerations associated with treatment of amblyopia in older children, along with recent amblyopia treatment advances that could have an impact on treatment prospects for this patient group. Considerations include the risks, benefits and efficacy of treating newly diagnosed amblyopia in older children, monitoring density of suppression to mitigate intractable diplopia risk, and recent findings regarding binocular treatments for amblyopia

Strabismus as a Presenting Sign in Retinoblastoma

PURPOSE:To report the presenting signs of retinoblastoma in a large cohort of patients who underwent orthoptic assessment at presentation. METHODS:A retrospective medical chart review was conducted on 131 patients with retinoblastoma who presented consecutively to a single institution during a 6-year period. The main outcome measure was the presenting sign(s) of the disease. RESULTS:Of 131 patients with retinoblastoma, 88 presented with unilateral disease and 43 presented with bilateral disease (mean ages: 22.7 and 14.8 months, respectively). Leukocoria was the presenting sign in 56% of patients, leukocoria and strabismus in 18%, strabismus in 13%, inflammation in 8%, and “other” signs in 5%. The fovea was affected by the retinoblastoma tumor or its sequelae in 75% of patients. Patients who presented with strabismus were significantly more likely to have foveal involvement than patients who presented with leukocoria alone (P = .001). Thirty-one percent of patients had strabismus as a component of their presentation; 63% had exotropia, 23% had esotropia, and 14% had variable strabismus. The percentage of patients with strabismus increased to 66% when small angle and variable strabismus were also considered. Patients with inflammation had worse ocular survival (P < .05). CONCLUSIONS:This study assessed the combination of leukocoria and strabismus as presenting features of retinoblastoma. Foveal involvement is common in patients who have strabismus and may influence decision-making regarding globe salvage. The authors confirmed that exotropia is more common than esotropia in retinoblastoma in the largest cohort to have undergone an orthoptic assessment

Retinal Neuronal Ectopia: a new entity in the differential diagnosis of retinoblastoma

BACKGROUND: To present a rare retinal disorder that should be considered in the differential diagnosis of retinoblastoma. METHODS: A 2-year-old boy presented with left ocular discomfort, leukocoria, and a left divergent squint. Examination of the left eye revealed abnormalities in the anterior segment, and fundoscopy showed an irregular white calcified mass with fibrosis and traction toward the lens. As the ocular discomfort worsened, enucleation of the left eye was performed. RESULTS: Histopathological and immunohistochemical assessment of the enucleated eye established the diagnosis of retinal neuronal ectopia. CONCLUSION: We believe that this case is unique in the human retina and highlights the need for specialist differential diagnosis. Although rare, retinal neuronal ectopia should be considered in the differential diagnosis of retinoblastoma

Retinoblastoma and vision

The assessment of vision has a growing importance in the management of retinoblastoma in the era of globe-conserving therapy, both prior to and after treatment. As survival rates approach 98-99% and globe salvage rates reach ever-higher levels, it is important to provide families with information regarding the visual outcomes of different treatments. We present an overview of the role of vision in determining the treatment given and the impact of complications of treatment. We also discuss screening and treatment strategies that can be used to maximise vision