Book chapters will be unavailable on Saturday 24th August between 8am-12pm BST. This is for essential maintenance which will provide improved performance going forwards. Please accept our apologies for any inconvenience caused.
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 email@example.com
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.
Cobalt-doped ZnO (CZO) film nanocomposites have been deposited on Si(100) substrates by pulsed electron beam ablation from a single Co0.2Zn0.8O target. The films have been deposited at various electron beam repetition rates (1, 2, 4, and 8 Hz), under a background argon (Ar) pressure of ∼3 mtorr, an accelerating voltage of 16 kV, and a deposition temperature of 450 °C. The effect of beam frequency on the structural, chemical, and morphological properties of the films has been assessed. The findings reveal that film thickness, film roughness, and degree of crystallinity of the ZnO wurtzite structure increase with beam frequency, while globule size and density reach maximum and minimum values, respectively, as the beam frequency is increased. The pulse frequency does not appear to affect the average nanoparticulate size. X-ray photoelectron spectroscopy data support the co-existence of metallic cobalt (Co0), CoO, and Co2O3 in CZO films near the surface. Phase analysis by X-ray diffraction also confirms the presence of hexagonal close-packed metallic cobalt whose content in the films is practically unaffected by beam frequency.
Millimeter-wave (mm-wave) beam-steering antennas are preferred for reducing the disruptive effects, such as those caused by high atmospheric debilitation in wireless communications systems. In this work, a compact broadband antenna array with a low loss feed network design is introduced. To overcome the short-range effects on mm-wave frequencies, a feed network – with a modified Butler matrix and a compact zeroth-order resonance antenna element – has been designed. Furthermore, the aperture feed technique has been utilized to provide a broadside stable pattern and improve the delivered gain. A Fabry-Perot layer without the height of the air layer is used. Taking advantage of this novel design, a broadband and compact beam-steering array antenna – capable of covering impedance bandwidths (from 33.84 to 36.59 GHz) and scanning a solid angle of about ~94°, with a peak gain of 17.6 dBi – is attained.
Strenuous physical exercise and hyperthermia may paradoxically induce oxidative stress and adverse effects on myocardial function. The purpose of this study was to investigate the effect of 14-d coenzyme Q10 (CoQ10) supplementation and pre-cooling on serum creatine kinase-MB (CK-MB), cardiac Troponin I (cTnI), myoglobin (Mb), lactate dehydrogenase (LD), total antioxidant capacity (TAC), lipid peroxidation (LPO) and CoQ10 concentration in elite swimmers. In total, thirty-six healthy males (mean age 17 (sd 1) years) were randomly selected and divided into four groups of supplementation, supplementation with pre-cooling, pre-cooling and control. During an eighteen-session protocol in the morning and evening, subjects attended speed and endurance swimming training sessions for 5 km in each session. Blood sampling was done before (two stages) and after (two stages) administration of CoQ10 and pre-cooling. ANCOVA and repeated measurement tests with Bonferroni post hoc test were used for the statistical analysis of the data. There was no significant statistical difference among groups for the levels of CK-MB, cTnI, Mb, LD, TAC, LPO and CoQ10 at the presampling (stages 1 and 2) (P>0·05). However, pre-cooling and control groups show a significant increase in the levels of CK-MB, cTnI, Mb, LD and LPO compared with the supplementation and supplementation with pre-cooling groups in the post-sampling (stages 1 and 2) (P<0·05), except for the TAC and CoQ10. Consequently, CoQ10 supplementation prevents adverse changes of myocardial damage and oxidative stress during swimming competition phase. Meanwhile, the pre-cooling strategy individually has no desired effect on the levels of CK-MB, cTnI, Mb, LD, LPO, TAC and CoQ10.
The addition of acids generally lowers the pH and buffering capacity of the diet, reduces pH within the stomach, increases both gastric proteolysis and nutrient digestibility, promotes beneficial bacteria at the expense of pathogenic organisms and decreases intestinal bacterial growth. As a consequence there is an improvement in gastrointestinal health, resulting in enhanced growth performance and improved feed efficiency. Mixture of Organic acids has shown to be an effective alternative to eliminate salmonellas in feeds and chickens. Organic acids reduce the pH in the digestive tract and are able to suppress the growth of undesired micro organisms, mainly in the upper part of the digestive tract depending on the place and rate of absorption. The faster the acids are absorbed the smaller is the pH lowering effect. This effect is directly influenced by the acid binding capacity of the diet. Therefore the aim of this study was to determine that antibiotic growth promoter could be replaced by a mixture of organic acids.
Antibiotic growth promotion in agricultural animal production has been practiced for about 50 year in the United States and other countries. Early indications were for a beneficial effect on production efficiency in poultry and swine. There were early concerns about the development of antibiotic resistance in human pathogens resulting in recommendations to ban sub therapeutic use in animal feeds. One of the best alternatives for antibiotic growth promoters are organic acids. Organic acids mixtures have been shown to be an effective alternative to eliminate salmonellas in feeds and chickens. Various organic acid combinations were tested to prevent Salmonella contamination through the ration in day-old chicks, and it was observed that a mixture of formic (70%) and propionic acid (30%), was efficient to eliminate S. enteritidis and S. thyphimurium, both of great importance in human health and increase growth rate in broiler.
Late Cenozoic basalts of the Bazman volcanic field, Makran volcanic arc of
southern Iran, contain two types of plagioclase feldspar phenocrysts with
significant textural and compositional differences. The most common type is
rather homogeneous with only weak zoning and maximum An content of 83 mol.%.
The less common type of phenocryst exhibits complex zoning and, other than
rims, is close in composition and similar in texture to those of associated
andesites. This type of plagioclase phenocryst is characterized by an
engulfed core with oscillatory zoning, which is overgrown by sieve-textured,
moderately zoned mantle, and a relatively narrow rim. In both rock types,
the An content of the core is between 40 and 63 mol.% with abrupt
fluctuations. No significant correlation between An content and MgO, FeO,
SrO and BaO is apparent in the core of phenocrysts in basalts. Anorthite
content of the core of phenocrysts in andesites inversely correlates with
SrO and BaO. The mantle of plagioclase phenocrysts in both rock types is
characterized by sharp increases of An (up to 41 mol.%), MgO, and FeO, in
the contact with the core. Anorthite correlates positively with MgO and FeO
in the mantle, but correlation between An and SrO and BaO is not evident. It
is assumed that plagioclase phenocrysts originally crystallizing from the
host andesitic magma were interrupted by mixing with a hotter, juvenile
basaltic magma. The resulting changes in temperature, composition, and
H2O content of the surrounding melt caused compositional
zonation, and the development of resorption in the cores and sieve texture
in the mantles. As the An contents of the rims of the phenocrysts resemble
the average An content of the groundmass plagioclases in both rock types, it
is thought that the two involved magmas gained their independent physical
identity before the formation of compositionally-distinct rims of
The population density of the diamondback moth (DBM), Plutella xylostella (L.), the species diversity of its predators, parasitism on eggs, larvae and pupae, and associated yield of canola were evaluated in experimental plots where spring canola was grown either as a monoculture or strip-intercropped with annual alfalfa in the ratio of 3C:3A, 6C:3A and 9C:3A over a 2-year period. The egg density was significantly higher in monoculture than in intercrops. The highest and lowest densities of larvae and pupae of DBM were recorded in monoculture (2.9–3.2 larvae per plant and 1.14–1.20 pupae per plant) and intercrop 3C:3A (0.7–0.6 larvae per plant and 0.34–0.29 pupae per plant), respectively. Shannon diversity index (H') for species composition of the predators of DBM immature stages was lower in monoculture than in intercrops, and was similar amongst the three intercrops. Moreover, the percent parasitism for eggs, larvae and pupae was higher in intercrops than in monoculture. The dry seed weight loss was higher in monocrop (37.6–40.1%) compared to 3C:3A (7.9–8.6%), 6C:3A (19.5–21.4%) and 9C:3A (21.6–25.4%). Our results indicate that intercropping canola with annual alfalfa, especially in the ratio 3C:3A, can increase the species diversity, parasitism rates of DBM immature stages, and enhance the yield of canola. The implications of these findings, in relation to integrated pest management (IPM) in canola cropping systems, are discussed.
The anthocorid bug Orius albidipennis Reuter is a generalist predator that feeds on the whitefly Bemisia tabaci Gennadius and the strawberry spider mite Tetranychus turkestani Ugarov & Nikolski in greenhouse crops. There are no previous studies on the potential efficacy of the predatory bug against these pests on greenhouse crops. We report on the efficacy and the prey preference of the predator to control these pests on different host plants under laboratory conditions. In a laboratory experiment, we estimated the predation rates of O. albidipennis at different densities of each prey after 24 h on cucumber and sweet pepper leaves. Predation rates of the predatory bug to T. turkestani and B. tabaci were significantly higher on sweet pepper leaf than on cucumber leaf. We studied the effect of plant species on prey preference and switching of O. albidipennis to B. tabaci and T. turkestani using Manly's α index values and Murdoch's no-switch line, respectively. Our results show that O. albidipennis prefers T. turkestani to B. tabaci on both host plants but its preference for T. turkestani on sweet pepper is significantly greater than on cucumber. Moreover, on sweet pepper, preference values are completely fitted by Murdoch's no-switch line. The findings suggest that morphological defence traits of plants, such as hairy leaves of cucumber, may effectively change prey preference and reduce predation success of O. albidipennis.
Trajectory tracking is one of the main control problems in the context of Wheeled Mobile Robots (WMRs). Control of underactuated systems has been focused by many researchers during past few years. In this paper, tracking control of a Tractor–Trailer Wheeled Mobile Robot (TTWMR) has been discussed. TTWMR includes a differential drive WMR towing a passive spherical wheeled trailer. Spherical wheels in contrast with standard wheels make the robot highly underactuated with severe non-linearities. Underactuation is due to the use of spherical wheeled trailer to increase robots' maneuverability and degrees of freedom. In fact, standard wheels are subjected to non-holonomic constraints due to pure rolling and non-slip conditions, which reduce robot maneuverability. In this paper, after introducing the robot, kinematics and kinetics models are obtained. Then, based on a physical intuition, a novel control algorithm is developed for the robot, i.e. Lyapunov-PID control algorithm. Subsequently, singularity avoidance of the proposed algorithm is discussed and the stability of the algorithm is analyzed. Finally, simulation and experimental results are presented which reveal the effectiveness of the proposed algorithm.
A new design of reconfigurable sub-nanosecond pulse generator (PG) with pulse shape selection ability is presented in this paper. Step recovery diode is used as the pulse sharpening device and the pulse shaping circuit consists of a controllable RC differentiator in which a single PIN diode is embedded, which provides two different switchable pulse shaping performances. The realized PG has a compact (10 × 12 mm2) simple structure and is easy to implement while generating Gaussian and monocycle pulses with 510 and 660 ps pulse width, respectively. The proposed pulse shaping method is versatile and can be effectively modified and reconfigured to generate more complicated pulse shapes such as polycycle signals. The measured results reveal that the proposed reconfigurable PG is suitable to be used in systems with pulse shape modulation that require sub-nanosecond pulses at low pulse repetition rates.
This study reports on the preparation of cobalt doped zinc oxide (Co:ZnO) films
via pulsed electron beam ablation (PEBA) from a single target containing 20 w%
Co on sapphire (0001) and silicon (100) substrates. The films have been
deposited at various temperatures (350оC,
400оC, 450оC) and pulse
frequencies (2 Hz, 4 Hz), under a background argon (Ar) pressure of about 3
mtorr, and an accelerating voltage of 14 kV. The surface morphology has been
examined by atomic force microscopy (AFM) and scanning electron microscopy
(SEM). According to SEM analysis, the films consist of nano-globules whose size
is in the range of 80-178 nm. Energy dispersive x-ray spectroscopy (EDX) reveals
that deposition is congruent and the prepared films contain
∼20±5 w% cobalt. It has been found that the nano-globules in
the deposited films are cobalt-rich zones containing ∼70 w% Co. From
x-ray photoelectron spectroscopy (XPS) analysis, Co 2p3/2 peaks
indicate that the deposited films contain CoO (binding energy = 780.5
eV) as well as metallic Co (binding energy = 778.1-778.5 eV). X-ray
diffraction (XRD) analysis supports the presence of metallic Co hcp phase
(2ϴ = 44.47° and 47.43°) in the films.
This study presents the influence of heat and mass transfer on peristaltic transport of Finitely Extensible Nonlinear Elastic Peterlin (FENE-P) fluid in the presence of chemical reaction. It is assumed that all the fluid properties, except the density are constant. The Boussinesq approximation which relates density change to temperature and concentration changes is used in formulating buoyancy force terms in the momentum equation. Moreover, we neglect viscous dissipation and include diffusion-thermal (Dufour) and thermal-diffusion (Soret) effects in the present analysis. By the consideration of such important aspects the flow equations become highly nonlinear and coupled. In order to make the problem tractable we have adopted widely used assumptions of long wave length and low Reynolds number. An exact solution of the simplified coupled linear equations for the temperature and concentration has been obtained whereas numerical solution is obtained for dimensionless stream function and pressure gradient. The effects of different parameters on velocity field, temperature and concentration fields and trapping phenomenon are highlighted through various graphs. Numerical integration has been performed to analyze pressure rise per wavelength.
A new genus and species of mites of the family Caraboacaridae (Acari: Heterostigmata), Intercaraboacarus clivinus Katlav and Hajiqanbar new genus, new species, associated with Clivina ypsilon Dejean, 1829 (Coleoptera: Carabidae), is described from Iran. It is the third genus of the family Caraboacaridae in the world. The new genus represents a combination of shared character states with the two previously described genera. An illustrated key to world genera of the family is provided. Differentiation of the new genus from other genera and distribution and host range of all known genera and species of the family are discussed.
This paper deals with an analytical solution of an oscillatory flow in a channel filled with a porous medium saturated with a viscous fluid. The consideration of porosity in the channel is the basic idea of the paper. The oscillatory waves in the channel with porous medium are produced due to self-excited pressure disturbances caused by inevitable fluctuation in a suction rate at the porous walls. The ensuing steady axial velocity and the time dependent oscillatory axial velocity are found analytically using perturbation method and WKB approximation. The important physical quantities like the velocity profile, amplitude of the oscillation and penetration depth of the oscillatory velocity have been given special emphasis in this analysis. The effects of porosity of the medium on these quantities are calculated analytically and examined graphically. We find that the amplitude of oscillatory velocity and the penetration depth of the oscillatory axial velocity decrease with increasing values of inverse Darcy parameter. The oscillations in the fluid can be minimized by decreasing the permeability of the medium.
The mite species Trochometridium mutilliphillum Loghmani and Hajiqanbar new species (Acari: Trombidiformes: Trochometridiidae) associated with two mutillid wasps of the genera Tricholabiodes Radoszkowski and Dentilla Lelej (Hymenoptera: Mutillidae) is described from northeastern Iran. Some new host records for species of the genus Trochometridium Cross are reported, including a remarkable new record of an association between the mite family Trochometridiidae and the order Diptera. Also, an illustrated key to world genera and species of the family Trochometridiidae is provided.
Hospital-treated self-poisoning is common, with limited effective interventions for reducing subsequent suicidal behaviour.
To test the efficacy of a postcard intervention to reduce suicidal behaviour.
Randomised controlled trial of individuals who self-poisoned (n = 2300), the intervention consisted of nine postcards sent over 12 months versus usual treatment. Outcomes assessed at 12 months (n = 2113) were suicidal ideation, suicide attempts and self-cutting (proportion and event rates).
There was a significant reduction in any suicidal ideation (relative risk reduction (RRR) = 0.31, 95% CI 0.22–0.38), any suicide attempt (RRR = 0.42, 95% CI 0.11–0.63) and number of attempts (incidence rate ratios (IRR) = 0.64, 95% CI 0.42–0.97). There was no significant reduction in any self-cutting (RRR = 0.14, 95% CI −-0.29 to 0.42) or self-cutting events (IRR = 1.03 95% CI 0.76–1.39).
A postcard intervention reduced suicidal ideation and suicide attempts in a non-Western population. Sustained, brief contact by mail may reduce suicidal ideation and suicide attempts in individuals who self-poison.
Quantum dots (QDs) have been shown to improve the efficiency and optical properties of opto- electronic devices compared to two dimensional quantum wells in the active region. The formation of self-assembled GaN nanostructures on aluminum nitride (AlN) grown on sapphire substrates by Metal Organic Chemical Vapor deposition (MOCVD) was explored. This paper reports on the effect of in-situ activation in nitrogen atmosphere on MOCVD grown GaN nanostructures. The effect of introducing manganese in these nanostructures was also studied. Optically active nanostructures were successfully obtained. A blue shift is observed in the photoluminescence data with a decrease in nanostructure size.
The incorporation of Mn into GaMnN epilayers by MOCVD growth was investigated. Samples with high Mn concentrations lead to room temperature ferromagnetism. In addition an absorption band around 1.5 eV was observed. Intensity and linewidth of this band scaled with the Mn concentration and with the room temperature (RT) saturation magnetization. This band is assigned to the internal Mn3+ transition between the 5E and the partially filled 5T2 levels of the 5D state. The broadening of the absorption band is introduced by the high Mn concentration. Recharging of the Mn3+ to Mn2+ was found to effectively suppress these transitions resulting also in a significant reduction of the RT magnetization. The pronounced sensitivity of the relative position of the Fermi level and 1.5 eV absorption band can be used to predict the magnetization behavior of the Ga1−xMnxN epilayers. The absence of doping-induced strain was observed by Raman spectroscopy. The structural quality, the presence of Mn2+ ions were confirmed by EPR spectroscopy, meanwhile no Mn-Mn interactions were observed.