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A series of radiocarbon dates for Early Bronze Age contexts from the excavations at Kouphovouno are published for the first time. By adopting a Bayesian modelling approach, the 14C estimates allow greater precision in arriving at an absolute chronology for the period. The opportunity is taken to place these dates as part of the more general development of the Early Bronze period. The sequence for mainland Greece is compared with the recently revised dating of the Early Cycladic period. The new data support a lower chronology than that advocated in recent publications.
A new silicide/silicon IR detector is presented which has the potential for multicolour detection due to the tunability of its photoresponse. This tunable internal photoemission sensor (TIPS) fabricated using the Ir/Si/ErSi2 system, consists of two back–to–back Schottky diodes separated by a thin undoped Si layer. The two metals have different Schottky barrier heights so that the depleted Si forms an asymmetrical potential barrier to the carriers photocreated in each metallic film. The photocurrent flowing between the two metallic films is therefore strongly dependent on the shape and height of the effective potential barrier that can be varied by a bias applied between the two metallic electrodes. The Ir/Si/ErSi2 photoresponse and cut–off wavelength are indeed dramatically modulated when a small bias (less than 1 volt) is applied between the Ir and ErSi2 electrodes. The quantum efficiencies, measured in the 1 to 3 μm range, are comparable to the best obtained in Schottky and SiGe/Si internal photoemission detectors. A quantitative model derived from the Fowler formalism (by taking into account (i) the hole and electron photocurrents and (ii) the wavelength dependence of the photon absorption in each metallic film) fits all the experimental data over the whole range of photon energy and applied biases. The effective barrier heights thus measured as a function of applied bias are in good agreement with those deduced from activation energy analysis of the TIPS dark current and show that the cut–off wavelength can be modulated from 2.5 μm to more than 6 μm. Finally, electrical and photoresponse measurements on Cr/Si/SiGe(p+) structures (using the same TIPS mode of operation) also demonstrate the photoresponse tunability, thus combining the TIPS tunability with the extended wavelength range of operation (up to 10 μm) of SiGe/Si detectors.
On 26 November 2010, an outbreak of scombroid fish poisoning occurred in the French Armed Forces in Dakar, Senegal. This chemical intoxication, due to high histamine concentration in fish, is often mistaken for an allergic reaction. A case-control study was undertaken including the 71 cases and 78 randomly selected controls among lunch attendees. The usual symptoms for scombroid fish poisoning were observed in cases, i.e. flushing (85·9%), headache (83·1%), rapid/weak pulse (59·1%) and diarrhoea (47·9%). Symptoms occurred from within a few minutes to up to 3 h following the meal. Most patients quickly recovered with antihistamine and/or symptomatic treatment. Tuna was the only food item positively associated with illness (odds ratio 36·3, 95% confidence interval 6·3–210·0), with the risk of illness increasing with the quantity of fish consumed. No bacterial contamination was found in leftover food, but histamine concentration in tuna was found to be 4900 mg/kg, almost 50-fold higher than the concentration allowed by European regulations. This report is unique because of the large size of the case series – to our knowledge, the largest event of scombroid fish poisoning ever reported – and the chemical and bacteriological analyses results obtained on leftover food.
A series of epitaxial Co/Cr superlattices has been grown by molecular beam epitaxy. The Cr is in a metastable hcp phase as confirmed by transmission electron microscopy, selected area diffraction, and reflection high energy electron diffraction. The Cr layers are 10Å thick in all samples while the Co layers are varied from 12Å to 40Å. The diffusion between Co and Cr is studied by SQUID magnetometry and indicates step-like interfaces in the best samples. Interfacial sharpness has also been found to be unusually sensitive to Co deposition rates, and in contrast with other superlattice systems, we find that sharper interfaces enhance parallel anisotropy. Hall effect measurements of the saturation field are within 10% of SQUID values. Magnetoresistance at 4.2K is only 1/3% which we believe is a consequence of the high density of states at the Fermi level of hcp Cr.
We demonstrate the growth of epitaxially ordered Cobalt-Chromium (Co-Cr) superlattices by ultrahigh-vacuum deposition techniques. The superlattices, consisting of hcp Co (00.1) and hcp Cr (00.1) layers with their [11.0] crystallographic axes parallel to GaAs  have a hexagonal closed packed (hcp) structure with the c-axis normal to the film plane.
We have studied the morphology and magnetic phase transitions of monolayer-range Fe films on a reconstructed Au(001) surface using the combination of High-Resolution Low-Energy Electron Diffraction (HRLEED) and Surface Magneto-Optic Kerr Effect (SMOKE) techniques. Through the measurement of energy dependent angular profiles of the specularly diffracted beam, we discovered a simple method to determine not only the interfacial spacings (Fe-Au and Fe-Fe) but also to detect the build up of the second layer. For a one-level (2-D) Fe films with coverage of ∼ 0.6 monolayer (ML) perpendicular magnetization was observed. For a 1 ML equivalent 3-D film both perpendicular and in-plane magnetization were observed. The magnetic phase transitions of these magnetic islands showed finite size broadening effect. The perpendicular saturation magnetization decreases with temperature above 100°C but never vanishes and the magnetization curve has no hysteresis loop above ∼ 120°C. The implication of superparamagnetism is discussed.
We present data from low-energy He+ ion scattering off a magnetized Fe(110) surface where we monitored the circular polarization of the light emitted from particles neutralized into excited states. We investigated the dependence on incident energy, incident angle and magnetization for a singlet and a triplet transition. As expected, there is no dependence on magnetization for the singlet state, but for the triplet transition we observed a difference in the circular polarization of as high as 32% when changing the direction of the magnetization.
We have investigated the magnetic arrangment of 3d transition-metal stepped surface by using a self-consistent real-space tight-binding method. As expected, the presence of steps modifies locally the properties of a transition-metal surface. We emphasized the influence of atomic environment. We found for the (100)-Fe surface, an enhancement of the magnetic moments of the external edge of this step as compared to the flat surface. The results are not very sensitives to the step length. More striking is the case of the (100)-V stepped surface where atoms at the external edge display a large magnetic moment.
We have grown a series of Fe(110)/Ag(111)/Fe(110) sandwich structures using a PHI 430B MBE system and analyzed their magnetic properties using transmission Mössbauer spectroscopy. The heterostructures consisted of two 30-monolayer (ML) 56Fe(110) slabs separated by an intervening Ag(111) layer 2 to 35 ML thick, with a 2 ML 57Fe Mössbauer probe layer placed at one of the Fe/Ag interfaces. We found that temperature dependence of the hyperfine field in the probe layer and the saturation hyperfine field value as well stronly depend on the Ag interlayer thickness. This result demonstrates that there exists an interlayer magnetic exchange interaction between the Fe layers across Ag. In addition, preliminary evidence suggests that this is probably an RKKY interaction.
A brief discussion of the resonant magnetic scattering process is given. Results from recent studies of thin Fe films and Fe/Gd multilayers are used as examples to demonstrate the information can be obtained and the unique features of this technique: large resonant enhancement, sensitivity to magnitization, elemental specificity, and tunability of the penetration depth. Comparison is made with related techniques: magneto-optical Kerr effect, Faraday effect, and magnetic circular dichroism.
We report the electronic structure of Pd(001) films with various thicknesses, within a self-consistent real-space description of the Hubbard Hamiltonian. We point out that the onset of ferromagnetism in Pd films is not a surface effect, but is directly related to the thickness of the slab: when the lattice parameter increases, films of two or three planes become ferromagnetic. Films with increasing thicknesses (from five layers to the bulk size) need a greater increase of the lattice parameter. An important supplementary lattice expansion is necessary to obtain a free-standing ferromagnetic monolayer. The surprising experimental results of Pd films on Ag or Fe substrate, are well described within this framework.
The contribution of strains to anomalous surface and interface magnetic anisotropies cannot be analyzed quantitatively without knowledge of the ME coupling coefficients there. We have measured the ME coupling coefficients Bs near the surface (~0.5nm) of two amorphous alloys, Fe77Cr6B17 (with bulk magnetostriction λs = +7 × 10−6) and Co76Cr4B20 (λs = -3.8 × 10−6) and found them to differ significantly from the bulk values Bb: Fe-base, Bs = -1.7 × 105 J/m3 (57% of Bb) and Co-base, Bs = 5.8 × 105 J/m3 (three times Bb).
Magnetic properties of sputtered Ni/Al multilayers have been investigated by vibrating sample magnetometry and ferromagnetic resonance. In these compositionally modulated films (CMFs) the Al ‘spacer’ layer thickness was fixed at 3.5 nm while the total Ni content of each film was held constant at 308 nm. The thickness of the individual Ni layers was varied from 4.8 to 154 nm. The CMFs showed a variety of magnetic characteristics which were dependent on the thickness of the Ni layers. CMFs with Ni layer thickness 30 nm and above showed clear evidence of perpendicular anisotropy. This anisotropy is characterized by low-remanence perpendicular hysteresis loops of the type commonly found in CoCr alloy films. As the Ni layer thickness diminishes the perpendicular anisotropy decreases and is eventually lost. Simultaneously, the CMFs show increasing in-plane remanence, rising to a peak squareness of greater than 0.5 at a Ni layer thickness of 11 nm. As the Ni thickness continues to decrease, the remanence again declines. At Ni thicknesses of a few nm the CMFs become quasi-superparamagnetic. These CMFs do not show a monotonic reduction in saturation magnetization, Ms, with decreasing Ni layer thickness. Instead, both Ms and the coercivity, Hc, pass through a maximum in the region of 40–80 nm Ni layer thickness. FMR measurements were also made on these films. A plot of the effective anisotropy field produces data of a similar form to the Ms versus Ni layer thickness plot, again with a clear maximum. The FMR data also reveals interesting resonances in the films exhibiting perpendicular anisotropy. The presence of satellite resonances adjacent to the principal resonance peaks seems to suggest, in structural terms, a two-phase system as the basis of the observed anisotropy.
Inflammatory bowel diseases (IBD) are immunomediated ailments affecting millions of individuals. Although diet is regarded as an important factor influencing IBD, there are no accepted dietary recommendations presently available. We administered 7·6 % lyophilised apples obtained from two cultivars (Golden Delicious and Marie Ménard, low and high in polyphenols, respectively) to HLA-B27 transgenic rats which develop spontaneous IBD. After 3 months feeding, rats fed Marie Ménard apples had reduced myeloperoxidase activity (3·6 (sem 0·3) v. 2·2 (sem 0·2) U/g tissue; P < 0·05) and reduced cyclo-oxygenase-2 (P < 0·05) and inducible NO synthase gene expression (P < 0·01) in the colon mucosa and significantly less diarrhoea (P < 0·05), compared with control rats. Cell proliferation in the colon mucosa was reduced significantly by feeding Golden Delicious apples, with a borderline effect of Marie Ménard apples. Gene expression profiling of the colon mucosa, analysed using the Whole Rat Genome 4 × 44 K Agilent Arrays, revealed a down-regulation of the pathways of PG synthesis, mitogen-activated protein kinase (MAPK) signalling and TNFα–NF-κB in Marie Ménard-fed rats. In the stools of the animals of this group we also measured a significant reduction of bacteria of the Bacteriodes fragilis group. In conclusion, the administration of Marie Ménard apples, rich in polyphenols and used at present only in the manufacturing of cider, ameliorates colon inflammation in transgenic rats developing spontaneous intestinal inflammation, suggesting the possible use of these and other apple varieties to control inflammation in IBD patients.
In developing countries, vaccination against highly pathogenic avian influenza subtype H5N1 (HPAI) in free-range poultry flocks is usually implemented as periodic campaigns and newborn chicks are generally not vaccinated by farmers between vaccination passes. The demographic population turnover leads to a continuous decrease in the population immunity rate (PIR) over time. We present a simple Leslie matrix model for estimating population turnover and PIR dynamics in a hypothetical small-size vaccinated free-range poultry population. Four different vaccination scenarios were identified assuming necessary procedures to achieve immunity. The results indicate that high levels of population immunity are difficult to sustain. Assuming an animal immunity response of 80% after vaccination and a constant population size, PIR 4 months after vaccination was ⩽30% in all the scenarios. Predictions averaged over time showed mean PIR between 36% and 48%, which is below the population immunity thresholds for eradication approximated from R0 estimates.
The frequency response of the h.f. quadrupole probe is calculated to be used as a diagnostic tool for measurements of electron density and temperature. In §2 the magnetic field is assumed to be zero, and ion motions are neglected. For a Maxwellian plasma, the so-called ‘Landau wave approximation’ is compared with various more sophisticated treatments, such as numerical integration or super-Cauchy and multiple water-bag models. The range of validity of this approximation is shown to be large, and the results can be applied to the most interesting parts of the experimental observations. All results previously established are recovered with greater speed. Having studied various disturbances (collisions, inhomogeneity and relative motion of the probe with respect to the plasma), it is deduced that the best way to determine the electron temperature is to use the anti-resonances due to beating between the Landau wave and the cold plasma field. In § 3 we describe the quadrupole probe, launched in December 1971 as part of the CISASPE rocket experiment. To deduce the electron density and temperature from these measurements, it is necessary to consider the influence of a static magnetic field, such as the earth's magnetic field. The general case could be treated by numerical integration, though with great difficulty, but it is shown that in most ionospheric conditions, in the vicinity of the upper hybrid frequency ωT the above treatment is again possible, the plasma frequency simply being replaced by ωT, and the thermal velocity slightly modified. These assumptions are used to deduce the electron density and temperature profiles.
A final report is presented here on the excavation of four Areas at the prehistoric site of Kouphovouno, Sparta, Lakonia. Areas A and D were excavated as trials in 2001 and lie outside the land purchased by the BSA for the main campaigns, so they could not be excavated further, whilst Areas E and F had extensive deposits of historic date and were not further explored as being outside the remit of the main Kouphovouno Project. The excavations have yielded important Neolithic and Early Helladic II deposits, plus Bronze Age burials and later Roman remains. After summarising the aims of the Project and mentioning earlier work at the site, the report gives an account of the stratigraphy and finds and includes specialist reports on the human and animal bones, the ceramics, the chipped and ground stone and other finds. Also discussed is the relationship between the surface remains reported in BSA 99 and the excavated material.
A multidisciplinary research programme was developed to get a scientific expertise for the quality assessment of products obtained from cloned livestock. Thirty-seven bovine Holstein female clones of five different genotypes and their products were analysed in comparison with 38 control animals obtained by conventional artificial insemination and raised under the same conditions at the same experimental farm. Animal evaluation included over 150 criteria and more than 10 000 measurements to check the physiological status and health over a 3-year period. All the parameters studied were in the normal range for age and breed, but some significant differences were detected between clone and control groups in terms of delayed onset of puberty in clones, higher neutrophil counts in haematology or lower biochemical plasma concentrations of gamma glutamyl transferase. Milk and meat analyses were conformable to expected values. We, however, found some differences in fatty acid (FA) composition of milk and muscle suggesting a possible deviation in lipid metabolism as assessed by higher delta-9 desaturase activity indexes in both milk and muscles from clones compared with controls. Repeated muscle biopsies in the semitendinosus muscle of the same animals demonstrated a higher oxidative activity in muscle of young clones (8 months of age) compared with controls, suggesting a delayed muscle maturation in clones. Nutritional evaluation of milk and meat using the rat feeding trials did not show any difference between clone and control products for food intake, growth rate, body composition of the rats, nor for possible allergenicity. Possible reactivation of bovine endogenous retroviruses (BERVs) was analysed and compared between normal and cloned cattle. As expected, these BERV sequences are not transcribed and no RNA was detected in the blood of clones, donor animals or controls; therefore, it may be assumed that the sanitary risk associated with BERV sequences is not higher in cattle derived from somatic nuclear transfer than in cattle born from conventional reproduction. Our results confirm that the quality and safety of products (milk and meat) from adult and clinically healthy cloned cattle is globally similar to normal animals. However, from a strictly biological point of view, the slightly delayed maturation we observed in the muscle of clones together with some marginal differences identified in FA composition of both muscle and milk, point to the need for more refined analysis to totally exclude any risks from the consumption of those products.
This is the final report on the intensive survey at Kouphovouno, the prehistoric settlement just south of Sparta, in 1999–2000. As well as a total collection of the artefacts on the surface, there was a magnetometer survey of the site and a programme of environmental studies, for which a series of cores was taken. The site was first occupied in the 6th millennium and covered 4–5 ha in the Middle, Late/Final Neolithic and Early Helladic periods. Occupation continued in the Middle and Late Helladic periods and there is also evidence of Classical-Hellenistic and Roman activity. As well as pottery, the artefacts included chipped and polished stone tools. An analytical programme has investigated the source of the raw materials used for the latter.