A quadratic Bézier representation withholds a curve segment with free from loops, cusps and inflection points. Furthermore,
this rational form provides extra freedom to generate visually pleasing curves due to the existence of weights. In this
paper, we propose sufficient conditions for rational quadratic Bézier curves to possess monotonic increasing/decreasing
curvatures by means of monotone curvature tests which are based on the derivative of curvature functions. We have
derived a simple interval of the middle weight that assures the construction of a family of rational quadratic Bézier curves
to be planar spirals, which is characterized by the turning angle, end curvatures and the chords of control polygon.
The proposed formulation can be used by CAD systems for aesthetic product design, highway/railway design and robot
trajectory design avoiding unwanted curvature oscillations.
Kertas ini membincangkan satu keluarga lengkung peralihan satahan licin yang dibina menggunakan dua lingkaran kuartik Bezier. Lingkaran kuartik yang diperkenalkan ini mempunyai enam darjah kebebasan yang memberi kelebihan untuk mempelbagaikan rupa bentuk lingkaran di dalam selangnya. Kelicinan adalah dirujuk melalui ciri-ciri keselanjaran geometri G2 dan kelengkungan monoton yang dimiliki oleh sesuatu lengkung peralihan. Oleh sebab lengkungan ini tidak memiliki sebarang juring, gelung dan titik lengkok balas, di samping tanpa perubahan kelengkungan yang mendadak maka ia amat sesuai untuk aplikasi tertentu dalam Reka Bentuk Berbantukan Komputer (RBK) bagi memenuhi keperluan estatis serta kepentingan fungsinya seperti reka bentuk produk industri, trajektori robot tidak holonomi dan juga reka bentuk mendatar landasan kereta api serta lebuh raya. Sebagai suatu perwakilan polinomial, lingkaran kuartik Bezier ini mampu digabungjalinkan ke dalam sistem RBK yang kebanyakannya berasaskan perwakilan NURBS (nonuniform rational B-splines).
Non-destructive test which refers to electrical resistivity method is recently popular in engineering, environmental, archaeological and mining studies. Based on the previous studies, the results on electrical resistivity interpretation were often debated due to lack of clarification and evidences in quantitative perspective. Traditionally, most of the previous result interpretations were depending on qualitative point of view which is risky to produce unreliable outcomes. In order to minimise those problems, this study has performed a laboratory experiment on soil box electrical resistivity test which was supported by an additional basic physical properties of soil test like particle size distribution test (d), moisture content test (w), density test (ρbulk) and Atterberg limit test (LL, PL and PI). The test was performed to establish a series of electrical resistivity value (ERV) with different quantity of water content for clayey silt and silty sand in loose and dense condition. Apparently, the soil resistivity value was different under loose (L) and dense (C) conditions with moisture content and density variations (silty SAND = ERVLoose: 600 - 7300 Ωm & ERVDense: 490 - 7900 Ωm while Clayey SILT = ERVLoose: 13 - 7700 Ωm & ERVDense: 14 - 8400 Ωm) due to several factors. Moreover, correlation of moisture content (w) and density (ρbulk) due to the ERV was established as follows; Silty SAND: w(L) = 638.8ρ-0.418, w(D) = 1397.1ρ-0.574, ρBulk(L) = 2.6188e-6E-05ρ, ρBulk(D) = 4.099ρ-0.07 while Clayey SILT: w(L) = 109.98ρ-0.268, w(D) = 121.88ρ-0.363, ρBulk(L) = -0.111ln(ρ) + 1.7605, ρBulk(D) = 2.5991ρ-0.037 with determination coefficients, R2 that varied from 0.5643 – 0.8927. This study was successfully demonstrated that the consistency of ERV was greatly influenced by the variation of soil basic physical properties (d, w, ρBulk, LL, PL and PI). Finally, the reliability of the ERV result interpretation can be enhanced due to its ability to produce a meaningful outcome based on supported data from basic geotechnical properties.
Septic arthritis of the shoulder in pediatric patients should be diagnosed and treated urgently to prevent complications of the disease. However, early detection can be a challenge due to mild symptoms with ambiguous laboratory and radiological findings. We report a case of an eight-month-old girl who presented to us initially with pseudo paresis of her right shoulder without any signs suggestive of infection. After a negative ultrasound, she was discharged with analgesia upon improvement of range of motion. Three weeks later, she presented with recurrent shoulder pain associated with fever, swelling, elevated CRP, and osteomyelitis changes of the humeral head on a plain radiograph. We proceeded with a minimally invasive arthrotomy washout and commenced on IV antibiotics. At one month follow-up, she regained her full range of motion and recovered fully. No recurrence of septic arthritis until six-month follow-up. This write-up discusses the diagnostic challenge of pediatric shoulder septic arthritis and the surgical technique of minimally invasive arthrotomy washout in a pediatric patient.
Induction of c-fos in the spinal cord due to pain is well established. This study aims to look at the effects of acute swim stress on Fos-like immunoreactivity (FLI) induced by formalin and how it is modulated by ketamine and morphine. Acutely-stressed and non-stressed adult male Sprague Dawley rats were pretreated with intraperitoneal injection of ketamine 5 mg/kg (Ketava, Atlantic Lab), morphine 10 mg/kg (Rhotard, Custom Pharmaceutical), or saline, 5 minutes prior to experimentation. Rats were acutely stressed by swimming for 3 min in 20 degrees C water. Dilute formalin (Formaldehyde, Merck) was injected to the hindpaw and the formalin score recorded. Rats were then sacrificed and spinal cords (L4-L5) removed for immunohistochemical analysis of FLI. Two-way ANOVA showed significant effects of stress, drug and stress-drug interactions in formalin test and FLI. Both morphine and ketamine produced analgesia in the formalin test. In the saline stressed group, FLI was suppressed on the ipsilateral side (p<0.01) but increased on the contralateral side (p<0.01) compared with non-stressed saline. In morphine and ketamine stressed groups, FLI was increased on both ipsilateral and contralateral sides for morphine (ipsilateral: p<0.05; contralateral: p<0.001) and ketamine (ipsilateral: p<0.05, contralateral: p<0.05) compared with their corresponding non-stressed groups. In conclusion, presence of stress may lead to discrepancy between behavioural manifestation of pain and c-fos induction in the spinal cord.