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The first demonstration of laser action in ruby was made in 1960 by T. H. Maiman of Hughes Research Laboratories, USA. Many laboratories worldwide began the search for lasers using different materials, operating at different wavelengths. In the UK, academia, industry and the central laboratories took up the challenge from the earliest days to develop these systems for a broad range of applications. This historical review looks at the contribution the UK has made to the advancement of the technology, the development of systems and components and their exploitation over the last 60 years.
Laser–solid interactions are highly suited as a potential source of high energy X-rays for nondestructive imaging. A bright, energetic X-ray pulse can be driven from a small source, making it ideal for high resolution X-ray radiography. By limiting the lateral dimensions of the target we are able to confine the region over which X-rays are produced, enabling imaging with enhanced resolution and contrast. Using constrained targets we demonstrate experimentally a
X-ray source, improving the image quality compared to unconstrained foil targets. Modelling demonstrates that a larger sheath field envelope around the perimeter of the constrained targets increases the proportion of electron current that recirculates through the target, driving a brighter source of X-rays.
Clinicians need guidance to address the heterogeneity of treatment responses of patients with major depressive disorder (MDD). While prediction schemes based on symptom clustering and biomarkers have so far not yielded results of sufficient strength to inform clinical decision-making, prediction schemes based on big data predictive analytic models might be more practically useful.
We review evidence suggesting that prediction equations based on symptoms and other easily-assessed clinical features found in previous research to predict MDD treatment outcomes might provide a foundation for developing predictive analytic clinical decision support models that could help clinicians select optimal (personalised) MDD treatments. These methods could also be useful in targeting patient subsamples for more expensive biomarker assessments.
Approximately two dozen baseline variables obtained from medical records or patient reports have been found repeatedly in MDD treatment trials to predict overall treatment outcomes (i.e., intervention v. control) or differential treatment outcomes (i.e., intervention A v. intervention B). Similar evidence has been found in observational studies of MDD persistence-severity. However, no treatment studies have yet attempted to develop treatment outcome equations using the full set of these predictors. Promising preliminary empirical results coupled with recent developments in statistical methodology suggest that models could be developed to provide useful clinical decision support in personalised treatment selection. These tools could also provide a strong foundation to increase statistical power in focused studies of biomarkers and MDD heterogeneity of treatment response in subsequent controlled trials.
Coordinated efforts are needed to develop a protocol for systematically collecting information about established predictors of heterogeneity of MDD treatment response in large observational treatment studies, applying and refining these models in subsequent pragmatic trials, carrying out pooled secondary analyses to extract the maximum amount of information from these coordinated studies, and using this information to focus future discovery efforts in the segment of the patient population in which continued uncertainty about treatment response exists.
Dogs can be infected by a wide range of Bartonella spp., but limited studies have been conducted in tropical urban and rural dog populations. We aimed to determine Bartonella antibody prevalence in 455 domestic dogs from four tropical countries and detect Bartonella DNA in a subset of these dogs. Bartonella antibodies were detected in 38 (8·3%) dogs, including 26 (10·1%) from Colombia, nine (7·6%) from Brazil, three (5·1%) from Sri Lanka and none from Vietnam. DNA extraction was performed for 26 (63%) of the 41 seropositive and 10 seronegative dogs. Four seropositive dogs were PCR positive, including two Colombian dogs, infected with B. rochalimae and B. vinsonii subsp. berkhoffii, and two Sri Lankan dogs harbouring sequences identical to strain HMD described in dogs from Italy and Greece. This is the first detection of Bartonella infection in dogs from Colombia and Sri Lanka and identification of Bartonella strain HMD from Asia.
We investigate the vibrational properties of ultrananocrystalline diamond (UNCD) using molecular dynamics simulations. We compare the vibrational spectra of two UNCD models of average grain size 2 and 4 nm with single crystal diamond and an isolated nanodiamond (ND) particle. The vibrational spectra of the ND particle and UNCD models exhibit the effect of phonon confinement as well as undercoordinated atoms at the surface/interfaces. This is further reflected in the specific heat of UNCD models and the ND particle that showed enhancements over that of single crystal diamond. The excess specific heat in UNCD models in comparison to single crystal diamond is found to be maximum at approximately 350 K.
The scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.
In recent years infection caused by Salmonella serotype Enteritidis (SE) phage type 4 has spread through Europe but has been uncommon in the USA. The first recognized outbreak of this strain in the USA occurred in a Chinese restaurant in El Paso, Texas, in April 1993; no source was identified. In September 1993, a second outbreak caused by SE phage type 4 was associated with the same restaurant. To determine the cause of the second outbreak, we compared food exposures of the 19 patients with that of two control groups. Egg rolls were the only item significantly associated with illness in both analyses (first control group: oddsratio [OR] 8·2, 95% confidence interval [CI] 2·3–31·6; second control group: OR 13·1, 95% CI 2·1–97·0). Retrospective analysis of the April outbreak also implicated egg rolls (OR 32·4, 95% CI 9·1–126·6). Egg roll batter was made from pooled shell eggs and was left at room temperature throughout the day. These two outbreaks of SE phage type 4 likely could have been prevented by using pasteurized eggs and safe food preparation practices.
The velocity fluctuations of particles in a low-Reynolds-number fluidized bed have important similarities and differences with the velocity fluctuations in a low-Reynolds-number sedimenting suspension. We show that, like sedimentation, the velocity fluctuations in a fluidized bed are described well by the balance between density fluctuations due to Poisson statistics and Stokes drag. However, unlike sedimentation, the correlation length of the fluctuations in a fluidized bed increases with volume fraction. We argue that this difference arises because the relaxation time of density fluctuations is completely different in the two systems.
The photographs displayed above show the impact, spreading, and boiling history of n-heptane droplets on a stainless steel surface. The impact velocity, Weber number, and initial droplet diameter are constant (values of 1 m/s, 43 and 1.5 mm respectively), and the view is looking down on the surface at an angle of about 30°. The photographs were taken using a spark flash method and the flash duration was 0.5 μs. The dynamic behavior illustrated in the photographs is a consequence of varying the initial surface temperature.
The effect of surface temperature on droplet shape may be seen by reading across any row; the evolution of droplet shape at various temperatures may be seen by reading down any column. An entrapped air bubble can be seen in the drop when the surface temperature is 24°C. At higher temperatures vigorous bubbling, rather like that of a droplet sizzling on a frying pan, is seen (the boiling point of n-heptane is 98°C) but the bubbles disappear as the Leidenfrost temperature of n-heptane (about 200°C) is exceeded because the droplet become levitated above a cushion of its own vapor and does not make direct contact with the surface. The droplet shape is unaffected by surface temperature in the early stage of the impact process (t≤0.8 ms) but is affected by temperature at later time (cf. t≥ 1.6 ms) because of the progressive influence of intermittent solid-liquid contact as temperature is increased.
The determination of residual stresses and the analysis of phases in
zirconia layers obtained after oxidation of Zy-4 and Zr-1%Nb-O sheets have been
performed using X-ray diffraction with synchrotron radiation at 20 and 400°C.
These experimental analyses have been compared with calculations using a
micromechanical approach (thermoelastic behaviour) and also with a macroscopic
approximation of the thermal stress due to cooling. The main result is the small
influence of cooling on the residual stresses developing in the zirconia layer,
especially for Zr-1%Nb-O.
The mechanical properties and dislocation microstructure of single crystals with a range of compositions within the Fex-Ni60–x-Al40 pseudobinary system have been investigated, with the purpose of bridging the behavior from FeAl to NiAl. Experiments are focused on the compression testing of <001> oriented single crystals with compositions where x = 10, 20, 30, 40, and 50 (in atomic percent). Observations of a<111> dislocation morphologies at room temperature and both a<111> and non-a<111> dislocation activity at elevated temperatures are reported and discussed. Measurements of the yield strength, elastic modulus and strain hardening rates are reported, and the variation of strength with composition is correlated with dislocation dissociation and overall dislocation morphology.
Continuous phase separation or spinodal decomposition occurs within a miscibility gap through the selective amplification of long wavelength concentration waves to produce a two-phase modulated microstructure. To comprehensively study the formation of these modulated microstructures and the kinetics of continuous phase separation the behavior of the composition fluctuations in the decomposing material should be monitored directly. The atom probe field-ion microscope is an ideal instrument for this type of investigation of fine-scale microstructures because of its ultra-high spatial resolution and microchemical analysis capability.
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