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An outbreak of gastroenteritis affected 453 attendees (attack rate 28·5%) of six separate events held at a hotel in Singapore. Active case detection, case-control studies, hygiene inspections and microbial analysis of food, environmental and stool samples were conducted to determine the aetiology of the outbreak and the modes of transmission. The only commonality was the food, crockery and cutlery provided and/or handled by the hotel's Chinese banquet kitchen. Stool specimens from 34 cases and 15 food handlers were positive for norovirus genogroup II. The putative index case was one of eight norovirus-positive food handlers who had worked while they were symptomatic. Several food samples and remnants tested positive for Escherichia coli or high faecal coliforms, aerobic plate counts and/or total coliforms, indicating poor food hygiene. This large common-source outbreak of norovirus gastroenteritis was caused by the consumption of contaminated food and/or contact with contaminated crockery or cutlery provided or handled by the hotel's Chinese banquet kitchen.
Lead free niobate solid solutions can exhibit piezoelectric properties comparable to that of lead zirconate titanate piezoelectrics in the vicinity of its morphotropic phase boundary (MPB). Here we describe how (Na,K)NbO3 and (Na,K)NbO3-LiTaO3 solid solution thin films can be grown epitaxially by the hydrothermal method at temperatures of 200 °C or below in water and be made ferro- and piezoelectrically active by a simple 2 step post growth treatment.
To report a rare case of thyroglossal duct cyst carcinoma which presented with obstructive sleep apnoea, and to highlight the difficulties in making this clinical diagnosis.
Case report and review of the English language literature concerning thyroglossal duct cyst carcinoma.
Thyroglossal duct cyst carcinoma is a rare clinical entity found in only approximately 1 per cent of all patients operated upon for thyroglossal duct cyst. This condition usually presents in an identical manner to its benign counterpart; atypical presentations have not previously been reported. Our patient is the first reported case of a thyroglossal duct cyst carcinoma first presenting with symptoms of obstructive sleep apnoea, without a neck mass. Complete surgical excision with total thyroidectomy and lymph node clearance was performed, in view of the positive lymph node metastases (seen on imaging) and the need for post-operative radioiodine therapy.
Thyroglossal duct cyst carcinomas may present atypically, posing a diagnostic dilemma for the clinician. For patients diagnosed with obstructive sleep apnoea, it is imperative that a thorough otolaryngological examination be performed to exclude any underlying pathology.
The basic mechanism of reinforcement in tendons addresses the transfer of stress, generated by the deforming proteoglycan (PG)-rich matrix, to the collagen fibrils. Regulating this mechanism involves the interactions of PGs on the fibril with those in the surrounding matrix and between PGs on adjacent fibrils. This understanding is key to establishing new insights on the biomechanics of tendon in various research domains. However, the experimental designs in many studies often involved long sample preparation time. To minimise biological degradation the tendons are usually stored by freezing. Here, we have investigated the effects of commonly used frozen storage temperatures on the mechanical properties of tendons from the tail of a murine model (C57BL6 mouse). Fresh (unfrozen) and thawed samples, frozen at temperatures of −20°C and −80°C, respectively, were stretched to rupture. Freezing at −20°C revealed no effect on the maximum stress (σ), stiffness (E), the corresponding strain (ε) at σ and strain energy densities up to ε (u) and from ε until complete rupture (up). On the other hand, freezing at −80°C led to higher σ, E and u; ε and up were unaffected. The results implicate changes in the long-range order of radially packed collagen molecules in fibrils, resulting in fibril rupture at higher stresses, and changes to the composition of extrafibrillar matrix, resulting in an increase in the interaction energy between fibrils via collagen-bound PGs.
The indirect haemagglutination (IHA) test using sensitized turkey erythrocytes and the indirect immunofluorescence assay (IgM-IFA) was confirmed to be sensitive in the detection of a recent or current Pseudomonas pseudomallei infection in 19 culture-confirmed Singapore melioidosis patients. All were found to have antibody titres from 4 to 32 768 in the IHA test and 10 to 320 in the IgM-IFA test. When these tests were employed on sera from 16 immigrant Thai construction workers who died of sudden unexplained death syndrome (SUDS) and 73 healthy Thai fellow workers, 93·8% and 68·8% of SUDS cases had IHA titre of ≥ 4 and IgM-IFA titre of ≥ 10 respectively, in contrast to 39·7% and 12·3% found among healthy Thai workers. These data indicate that at the time of death, most of the SUDS patients had an active infection with P. pseudomallei, possibly resulting from reactivation of a latent infection. The aetiological role of P. pseudomallei as the major cause of SUDS is discussed.
Healthy young men were fed four diets for 2 weeks each providing natural fats containing palmitic acid (16 : 0) predominantly in the sn-1, 3 position of dietary TAG or containing 16 : 0 predominantly in the sn-2 position with low or high levels of linoleic acid (18 : 2n-6). Two treatments supplied 16 : 0 in the sn-1, 3 positions from palmstearin with low (3 % energy) or high (>7 % energy) 18 : 2n-6 and two treatments supplied 16 : 0 in the sn-2 position from lard with high or low levels of 18 : 2n-6. Diets contained 30–35 % energy as fat, 7–11 % energy as 16 : 0 and moderate levels of cholesterol. Fasting serum cholesterol and lipoprotein concentrations were measured. Cholesterol fractional synthesis rate (FSR) was determined by 2H incorporation. Diets providing 16 : 0 in the sn-2 position resulted in lower fasting serum total cholesterol (TC) and a lower TC:HDL ratio than diets providing 16 : 0 in the sn-1, 3 positions. Diets with high levels of 18 : 2n-6 significantly decreased the TC:HDL ratio, reaffirming the well-known cholesterol-reducing effect of 18 : 2n-6. A lower non-esterified cholesterol FSR was observed with low dietary levels of 18 : 2n-6. No differences between dietary treatments were found for serum HDL-cholesterol, LDL-cholesterol or TAG. It is concluded that dietary fats containing 16 : 0 in the sn-2 position may result in slightly lower fasting TC than diets providing 16 : 0 in the sn-1, 3 positions, while the level of n-6 polyunsaturated fat influences endogenous cholesterol synthesis.
Notified cases of dengue infections in Singapore reached historical highs in 2004 (9459 cases) and 2005 (13 817 cases) and the reason for such an increase is still to be established. We apply a mathematical model for dengue infection that takes into account the seasonal variation in incidence, characteristic of dengue fever, and which mimics the 2004–2005 epidemics in Singapore. We simulated a set of possible control strategies and confirmed the intuitive belief that killing adult mosquitoes is the most effective strategy to control an ongoing epidemic. On the other hand, the control of immature forms was very efficient in preventing the resurgence of dengue epidemics. Since the control of immature forms allows the reduction of adulticide, it seems that the best strategy is to combine both adulticide and larvicide control measures during an outbreak, followed by the maintenance of larvicide methods after the epidemic has subsided. In addition, the model showed that the mixed strategy of adulticide and larvicide methods introduced by the government seems to be very effective in reducing the number of cases in the first weeks after the start of control.
The biological changes in recurrent laryngeal cancer following radiotherapy are not fully understood. The authors investigated differences in the expression of p53, proliferating cell nuclear antigen (PCNA) and bcl-2 in laryngeal cancer specimens before radiotherapy and in recurrent laryngeal cancer specimens following radiotherapy in the same patients. The authors investigated the expression of p53, PCNA and bcl-2 by immunohistochemical stain in 30 specimens from 15 patients with primary laryngeal cancer and recurrent laryngeal cancer after radiotherapy.
The expression of p53 protein was significantly different in laryngeal cancer before radiotherapy (4/15, 26.7 per cent) compared with recurrent laryngeal cancer after radiotherapy (8/15, 53.3 per cent) (p < 0.05). The PCNA index was also significantly different in laryngeal cancer specimens before radiotherapy (mean, 11.9 per cent) compared with recurrent laryngeal cancer after radiotherapy (mean, 18.0 per cent) (p < 0.05). However, there was no statistically significant alteration of bcl-2 expression in primary compared with recurrent laryngeal cancer. The expression of p53 and PCNA increased in recurrent laryngeal cancers after radiotherapy, compared with that in laryngeal cancers before radiotherapy. Recurrent laryngeal cancers arising following radiotherapy became biologically aggressive.
Rutile and anatase TiO2 films were grown on glass substrates from acidic titanium precursor solutions from 60°C upwards. Anatase synthesized at 60°C had a crystallinity of 15% that increased to 54% for a growth temperature of 200°C. A similar crystallinity by conventional heat treatment of the 60°C material was attained only at 400°C. It is believed that more complete dehydration of titanium complexes at higher growth temperatures led to less disruption of the long range attractive forces required for the formation of the periodic crystalline lattice. Rutile films grown at 60°C were determined to have a refractive index of 2.4. This is lower than the bulk value of 2.65 because the as-synthesized rutile material was only 29% crystalline and also contained nano-sized pores.
This study estimates the maximum and minimum degrees of autocompaction for radiocarbon-dated Holocene mangrove sediments in Singapore, in order to correct apparent sediment accretion rates for the effects of sediment compression due to autocompaction. Relationships developed for a suite of modern (surface) sediment samples between bulk density, particle-size distribution, and organic matter content were used to estimate the initial (uncompacted) bulk density of buried and variably compressed Holocene sediments, based on the grain-size distribution and organic matter content of the sediment. The difference between measured (compacted) and initial (uncompacted) bulk density of each buried sediment interval can be interpreted as the amount of length shortening experienced by each interval since burial. This allows the elevation of samples selected for 14C dating to be corrected for the effects of autocompaction of the underlying sediment sequence, so that accurate estimates of vertical sediment accretion rates can be calculated.
The 3 Holocene mangrove sequences analyzed and dated for this study ranged in age from 2000 to 8500 cal BP. The effects of autocompaction are significant, even in comparatively thin sequences, with subsidence of up to 56 cm calculated for carbon-dated samples presently 2 m above incompressible basement. The vertical sediment accretion rates for these mangrove sequences ranged from 0.99 to 6.84 mm/yr and carbon sequestration rates ranged from 0.9 to 1.7 t/ha/yr, all within the range observed for comparable Holocene and modern mangrove sediments elsewhere.
Potassium tantalate powders were hydrothermally synthesized at 100 to 200 °C in 4 to 15 M aqueous KOH solutions. A defect pyrochlore, Kta2O5(OH). nH2O (n ≈ 1.4), was obtained at 4 M KOH, but at 7–12 M KOH, this pyrochlore was gradually replaced by a defect perovskite as the stable phase. At 15 M KOH, there was no intermediate pyrochlore, only a defect perovskite, 0.85Ta0.92O2.43(OH)0.57 0.15H2O. Synthesis at higher KOH concentrations led to greater incorporation of protons in the perovskite structures. The potassium vacancies required for charge compensation of incorporated protons could accommodate water molecules in the perovskite structure.
Multidrug-resistant Salmonella enterica subsp. enterica serotype Typhimurium DT104L was first reported in Singapore from mid-July to mid-October 2000. Salmonella strains isolated from clinical laboratories were submitted to a reference laboratory for serotyping, phage-typing and pulsed-field gel electrophoresis (PFGE) using XbaI restriction endonuclease. An epidemiological investigation was conducted to determine the source of infection and mode of transmission using a structured questionnaire. A total of 33 cases involving mainly infants and toddlers were detected in the 3-month long outbreak. The outbreak strain was of the R-type ACGSTSu, i.e. resistant to ampicillin, chloramphenicol, gentamicin, streptomycin, tetracycline and sulphonamide. PFGE showed all isolates had an indistinguishable pattern, indicating a common source of infection. Consumption of imported dried anchovy was found to be the vehicle of transmission after adjusting for all confounding variables in the case-control study using stepwise logistic regression (OR 25·6; 95% CI 3·9–167·9; P = 0·001). Imported dried seafood should be properly processed, packed, labelled, and thoroughly cooked to prevent transmission of multidrug-resistant S. Typhimurium.
Nitrogen-15 enriched ammonium sulphate was applied to micro-plots in a field in which two
leguminous (white clover and peas) and two non-leguminous (ryegrass and winter wheat) crops were
grown to produce 15N-labelled crop residues and roots during 1993/94. Nitrogen benefits and
recovery of crop residue-N, root-N and residual fertilizer-N by three succeeding winter wheat crops
were studied. Each crop residue was subjected to four different residue management treatments
(ploughed, rotary hoed, mulched or burned) before the first sequential wheat crop (1994/95) was
sown, followed by the second (1995/96) and third wheat crops (1996/97), in each of which residues
of the previous wheat crop were removed and all plots were ploughed uniformly before sowing. Grain
yields of the first sequential wheat crop followed the order: white clover > peas > ryegrass > wheat.
The mulched treatment produced significantly lower grain yield than those of other treatments. In the
first sequential wheat crop, leguminous and non-leguminous residues supplied between 29–57% and
6–10% of wheat N accumulated respectively and these decreased with successive sequential crops.
Rotary hoed treatment reduced N benefits of white clover residue-N while no significant differences
in N benefits occurred between residue management treatments in non-leguminous residues. On
average, the first wheat crop recovered between 29–37% of leguminous and 11–13% of non-leguminous
crop residues-N. Corresponding values for root plus residual fertilizer-N were between
5–19% and 2–3%, respectively. Management treatments produced similar effects to those of N
benefits. On average, between 5 to 8% of crop residue-N plus root and residual fertilizer-N was
recovered by each of the second and third sequential wheat crops from leguminous residues compared
to 2 to 4% from non-leguminous residues. The N recoveries tended to be higher under mulched
treatments especially under leguminous than non-leguminous residues for the second sequential
wheat crop but were variable for the third sequential wheat crop. Relatively higher proportions of
leguminous residue-N were unaccounted in ploughed and rotary hoed treatments compared with
those of mulched and burned treatments. In non-leguminous residue-N, higher unaccounted residue-N
occurred under burned (33–44%) compared with other treatments (20–27%).
This paper deals with the problem of constructing multidimensional biorthogonal periodic multiwavelets from a given pair of biorthogonal periodic multiresolutions. Biorthogonal polyphase splines introduced to reduce the problem to a matrix extension problem, and an algorithm for solving the matrix extension problem is derived. Sufficient conditions for collections of periodic multiwavelets to form a pair of biorthogonal Riesz bases of the entire function space are also obtained.
It is well known that passive vortex generators can be very effective in controlling separation by ‘re-energising’ the low momentum fluids at the boundary layers. They have been used extensively in many practical aerodynamic applications; both in external and internal flows. Typical examples include aerofoil stall alleviation and engine face distortion control in the jet aircraft intake during high angles of incidence. The general flow feature behind a vortex generator is that a pair of contra-rotating streamwise vortices would be formed which will significantly strengthen the flow at the boundary layers. However, the rationale for successful vortex generator designs is often poorly understood. In many cases, vortex generator designs have even been shown to be arbitrary. Anderson et al and Reichert and Wendt used rectangular fin and tapered fin vortex generators respectively, to eliminate the internal flow separation of S-shaped intake ducts. Both geometries were found to be equally effective. Weng and Guo successfully applied aerofoil shape type of vortex generators to suppress the swirl on the engine face of an S-shaped intake duct at high angles of incidence.