To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Prenatal and early-life environmental exposures play a key role in the development of atopy and allergic disease. The Family Atherosclerosis Monitoring In earLY life Study is a general, population-based Canadian birth cohort that prospectively evaluated prenatal and early-life traits and their association with atopy and/or allergic disease. The study population included 901 babies, 857 mothers and 530 fathers. Prenatal and postnatal risk factors were evaluated through questionnaires collected during the antenatal period and at 1 year. The end points of atopy and allergic diseases in infants were evaluated through questionnaires and skin prick testing. Key outcomes included atopy (24.5%), food allergy (17.5%), cow’s milk allergy (4.8%), wheezing (18.6%) and eczema (16%). The association between infant antibiotic exposure [odds ratio (OR): 2.04, 95% confidence interval (CI): 1.45–2.88] and increased atopy was noted in the multivariate analysis, whereas prenatal maternal exposure to dogs (OR: 0.60, 95% CI: 0.42–0.84) and acetaminophen (OR: 0.68, 95% CI: 0.51–0.92) was associated with decreased atopy. This population-based birth cohort in Canada demonstrated high rates of atopy, food allergy, wheezing and eczema. Several previously reported and some novel prenatal and postnatal exposures were associated with atopy and allergic diseases at 1 year of age.
The aim of this study was to estimate the amount of childhood hepatitis B virus transmission in children born in the UK, a very low-prevalence country, that is preventable only by universal hepatitis B immunization of infants. Oral fluid specimens were collected from schoolchildren aged 7–11 years in four inner city multi-ethnic areas and tested for the presence of antibody to hepatitis B core antigen (anti-HBc). Those found positive or indeterminate were followed up with testing on serum to confirm their hepatitis B status. The overall prevalence of anti-HBc in children was low [0·26%, 95% confidence interval (CI) 0·14–0·44]. The estimated average annual incidence of hepatitis B was estimated to be 29·26/100 000 children (95% CI 16·00–49·08). The total incidence that is preventable only by a universal infant immunization programme in the UK was estimated to be between 5·00 and 12·49/100 000. The study demonstrates that the extent of horizontal childhood hepatitis B virus transmission is low in children born in the UK and suggests that schools in the UK are an uncommon setting for the transmission of the virus. Targeted hepatitis B testing and immunization of migrants from intermediate- and high-prevalence countries is likely to be a more effective measure to reduce childhood transmission than a universal infant immunization programme.
We report observations by high resolution electron microscopy of model catalysts produced by impregnating MgO smoke particles with inorganic clusters. With the use of very low beam currents the substrates are of sufficiently low noise that we have been able to image cleanly both single atoms and very small clusters of size l-2nm in sufficient detail to determine their atomic structure. Two types of metal structures are observed: single atoms decorating atomic steps and in a few cases two-dimensional surface rafts, and a population of mainly single crystal with a few multiply twinned particles. The single crystal particles are pseudomorphically epitaxed on the MgO substrates.
II-VI semiconductor alloys have recently received considerable attention for their possible use in double heterostructure (DH) blue laser diodes (LDs).1-4 The purpose of this paper is to present the empirical pseudopotential method within virtual crystal approximation for calculating the band structure of MgZnSSe quaternary alloy. The dependence of band gap energies on alloy composition has shown that MgZnSSe can be a direct or an indirect semiconductor. Electron and hole effective masses are calculated for different composition. Camel's back structure for the X valley conduction band has been found for certain composition range.
Monoclinic ZrO2 and its supported catalysts Co/Ni/ZrO2 for catalytic decomposition of N2O have been studied with FTIR, EDAX, XPS, and the evaluation of activity of the catalysts. It is found that monoclinic ZrO2 alone has the catalytic effect for N2O decomposition although the gas decomposes on Co/Ni/ZrO2 more efficiently. The XPS study shows that only Co exists in the surface region of ZrO2. In evaluation experiments, it is found that when Co/Ni exceeds a threshold concentration, the conversion of N2O is no longer accelerated with the increase of Co/Ni content. The gas decomposition on Co/Ni/ZrO2 can be described as first order with respect to partial pressure of N2O. No nitrogen N(ls) photoelectrons were detected for the catalysts after N2O decomposition. Surface reactions on ZrO2 and Co/Ni/ZrO2, including the behaviour of retained carbon (Cls) and N2O decomposition mechanism, will also be addressed.
We describe the fabrication of self-aligned split gate electrodes on suspended multiwalled carbon nanotube structures. A suspended multiwalled carbon nanotube structure was used as an evaporation mask for the deposition of metal electrodes resulting in the formation of discontinuous wire deposition. The metal deposits on the nanotubes are removed with lift-off due to the poor adhesion of metal to the nanotube surface. Using Al sacrificial layers, it was possible to fabricate self-aligned contact electrodes and control electrodes nanometers from the suspended carbon nanotubes with a single lithography step. It was also shown that the fabrication technique may also be used to form nano-gaped contact electrodes. The technique should prove useful for the fabrication of nano-electromechanical systems.
In this paper we review the use of high pressure techniques to investigate the optical properties of partially ordered GalnP epitaxial layers grown on GaAs substrates. In particular, we demonstrate the ability of high pressure to modify the band alignment at the GalnP/GaAs interface and hence to alter the optical properties of heterostructures fabricated from partially ordered GalnP on GaAs.
An alternative method for seeding catalyst nanoparticles for carbon nanotubes and nanowires growth is presented. Ni nanoparticles are formed inside a 450 nm SiO2 film on (100) Si wafers through the implantation of Ni ions at fluences of 7.5×1015 and 1.7×1016 ions cm−2 and post-annealing treatment at 700, 900 and 1100 °C. After exposed to the surface by HF dip etching, the Ni nanoparticles are used as catalyst for the growth of vertically aligned carbon nanotubes by direct current plasma enhanced chemical vapor deposition.
We investigated the performance of 65nm pFETs whereby the source and drain extensions (SDE) were implanted with Carborane, (C2B10H12) a novel form of molecular species. The high atomic mass of this molecule (146 a.m.u.) and the number of boron atoms transported per ion enables the productivity at low energy required for manufacturing of ultra shallow junctions for advanced scaling. In this investigation, Carborane was implanted at 13 keV to produce a Boron profile near equivalent to that produced by the reference BF2 implant. Results of electrical measurements did not exhibit any compromise in the I-V characteristics in terms of Id-Vg and Id-Vd and Ion-Ioff. External resistance and Vt roll-off shifted slightly with respect to the reference devices. This is attributed to a deeper junction with Carborane due to slight offset in the profile matching. It will be shown that with fully matched profiles, a perfect match of the device characteristics can be achieved.
In this paper, an efficient computation method is developed for solving a general class of minmax optimal control problems, where the minimum deviation from the violation of the continuous state inequality constraints is maximized. The constraint transcription method is used to construct a smooth approximate function for each of the continuous state inequality constraints. We then obtain an approximate optimal control problem with the integral of the summation of these smooth approximate functions as its cost function. A necessary condition and a sufficient condition are derived showing the relationship between the original problem and the smooth approximate problem. We then construct a violation function from the solution of the smooth approximate optimal control problem and the original continuous state inequality constraints in such a way that the optimal control of the minmax problem is equivalent to the largest root of the violation function, and hence can be solved by the bisection search method. The control parametrization and a time scaling transform are applied to these optimal control problems. We then consider two practical problems: the obstacle avoidance optimal control problem and the abort landing of an aircraft in a windshear downburst.
An outbreak of typhoid caused by Salmonella typhi of the same Vi-phage type (D1) and of the same antibiogram was reported in a large psychiatric institution in Singapore. A total of 95 (4·8%) of the 1965 inmates were infected, 47 with symptoms and 48 asymptomatic. Transmission was through close person-to-person contact and not through contaminated food or water. The source of infection could not be established. The outbreak was brought under control by maintaining a high standard of environmental sanitation, active search for fever and diarrhoeal cases, identification of asymptomatic cases by rectal swabbing, and isolation of those found to be infected. Mass immunization with two doses of heat-phenol inactivated typhoid vaccine was also carried out concurrently. The vaccine was found to have an efficacy of 65·8% in preventing clinical illness.
In this paper, we consider a linear program with only equality constraints but containing interval and random coefficients. We first address the linear program with interval coefficients, and establish some structural properties of this linear program. On this basis, a solution method is proposed. We then move on to consider the linear program with random coefficients. Using the chance constraint approach and a new approach, the satisfaction degree approach, we obtain the two respective deterministic equivalent formulations. Then the results and the numerical solution methods obtained for these two linear models are applied to the original linear problem which contains both interval and random coefficients. By way of illustration, we consider a practical problem, where the optimal mixing proportions need to be determined for the mix slurry in the production process of aluminium with sintering. This gives rise to a linear program with interval and random coefficients. Its deterministic equivalent formulations are presented. Preliminary numerical examples show that the proposed models and the solution methods are promising.
To determine the incidence of complications following temperature-controlled radiofrequency treatment of the soft palate, uvula and tongue base.
Settings and methods:
We included all patients who had received temperature-controlled radiofrequency treatment of the soft palate, uvula and tongue base, for sleep-disordered breathing, over a four-year period in a tertiary hospital. Patients' medical records were systematically reviewed for radiofrequency treatment parameters and complications.
Main outcome measure:
Seventy-six patients had been treated, with a total of 127 treatment sessions and 544 lesions to the palate, uvula and tongue base. The incidences of minor and moderate complications were, respectively, 2.6 per cent (14/544 lesions) and 0.4 per cent (2/544 treatment lesions), being 3.0 per cent (16/544 lesions) overall. Subdividing by anatomical region, the incidences of minor and moderate complications following palatal and uvula radiofrequency treatment were, respectively, 3.1 per cent (14/446 lesions) and 0 per cent, and those following tongue base treatment were, respectively, 0 per cent and 2.0 per cent (2/98 lesions). The incidence of minor complications following soft palate and uvula treatment, per treatment session, was 10.9 per cent. The incidence of moderate complications following tongue base treatment, per treatment session, was 4.6 per cent. There were no major complications in our study population.
In this study, the incidence of complications of temperature-controlled radiofrequency treatment of the palate, uvula and tongue base was low. Temperature-controlled radiofrequency is a safe treatment modality for patients with sleep-disordered breathing and can be performed as a day case procedure. We recommend day admission for patients undergoing radiofrequency of the tongue base, in view of the potential for severe complications and airway compromise.
In this paper, we develop a discretisation algorithm with an adaptive scheme for solving a class of combined semi-infinite and semi-definite programming problems. We show that any sequence of points generated by the algorithm contains a convergent subsequence; and furthermore, each accumulation point is a local optimal solution of the combined semi-infinite and semi-definite programming problem. To illustrate the effectiveness of the algorithm, two specific classes of problems are solved. They are relaxations of quadratically constrained semi-infinite quadratic programming problems and semi-infinite eigenvalue problems.
In this paper, we first discuss some basic properties of semipreinvex functions. We then show that the ratio of semipreinvex functions is semipreinvex, which extends earlier results by Khan and Hanson  and Craven and Mond . Finally, saddle point optimality criteria are developed for a multiobjective fractional programming problem under semipreinvexity conditions.
In this paper, we consider the numerical solution of a class of optimal control problems involving variable time points in their cost functions. The control enhancing transform is first used to convert the optimal control problem with variable time points into an equivalent optimal control problem with fixed multiple characteristic time (MCT). Using the control parametrization technique, the time horizon is partitioned into several subintervals. Let the partition points also be taken as decision variables. The control functions are approximated by piecewise constant or piecewise linear functions in accordance with these variable partition points. We thus obtain a finite dimensional optimization problem. The control parametrization enhancing control transform (CPET) is again used to convert approximate optimal control problems with variable partition points into equivalent standard optimal control problems with MCT, where the control functions are piecewise constant or piecewise linear functions with pre-fixed partition points. The transformed problems are essentially optimal parameter selection problems with MCT. The gradient formulae for the objective function as well as the constraint functions with respect to relevant decision variables are obtained. Numerical examples are solved using the proposed method.
The prevalence and genetic diversity of hepatitis C infection in women attending antenatal
clinics in two regions of England was investigated to inform future surveillance and control
measures. Women booking into antenatal care are routinely offered a test for immunity to
rubella. Serum residues from these tests were unlinked, anonymized and archived as part of the
Unlinked Anonymous Prevalence Monitoring Programme (UAPMP). The serum specimens
were tested for anti-HCV using a cost-effective pooling strategy. After taking into account
differential sampling from the UAPMP serum archive, the adjusted overall prevalence of anti-HCV
was 0·43% (95% CI: 0·32–0·53) in London and 0·21% (95% CI: 0·14–0·28) in the
Northern and Yorkshire region. Restriction fragment length polymorphism of amplified HCV
RNA identified type 3a as the most common HCV genotype in these antenatal women. The
prevalence of anti-HCV in antenatal women in the UK is low and consistent with that
expected from injecting drug use.
In this paper a bridging method is introduced for numerical solutions of one-dimensional global optimization problems where a continuously differentiable function is to be minimized over a finite interval which can be given either explicitly or by constraints involving continuously differentiable functions. The concept of a bridged function is introduced. Some properties of the bridged function are given. On this basis, several bridging algorithm are developed for the computation of global optimal solutions. The algorithms are demonstrated by solving several numerical examples.
Room-temperature photovoltaic spectroscopy was applied to study undoped GaN, n-type GaN, and InGaN quantum well structures. Clear exciton absorption was observed in the photovoltaic spectra of the undoped GaN, and polarization measurements were made to identify the exciton absorption. For the n-type GaN sample, instead of the exciton absorption we observed only bulk absorption edge, which may be due to the free carrier screening effect. For the InGaN quantum well structures, the photovoltaic spectra showed relatively complicated line shape due to the overlap of the signals from different layers. By changing the reference phase of the lock-in amplifier, we were able to suppress some of the signals and thus identify the origin of the corresponding signal.
In management science and system engineering, problems with two incommensurate objectives are often detected. Bicriterion optimization finds an optimal solution for the problems. In this paper it is shown that bicriterion discrete optimal control problems can be solved by using a parametric optimization technique with relaxed convexity assumptions. Some necessary optimality conditions for discrete optimal control problems subject to a linear state difference equation are derived. It is shown that in this case no adjoint equation is required.