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.
Choline is an important nutrient for humans. Choline intake of the European population was assessed considering the European Food Safety Authority European Comprehensive Food Consumption Database and the United States Department of Agriculture Nutrient Database. Average choline intake ranges were 151–210 mg/d among toddlers (1 to ≤3 years old), 177–304 mg/d among other children (3 to ≤10 years old), 244–373 mg/d among adolescents (10 to ≤18 years old), 291–468 mg/d among adults (18 to ≤65 years old), 284–450 mg/d among elderly people (65 to ≤75 years old) and 269–444 mg/d among very elderly people (≥75 years old). The intakes were higher among males compared with females, mainly due to larger quantities of food consumed per day. In most of the population groups considered, the average choline intake was below the adequate intake (AI) set by the Institute of Medicine in the USA. The main food groups contributing to choline intake were meat, milk, grain, egg and their derived products, composite dishes and fish. The main limitations of this study are related to the absence of choline composition data of foods consumed by the European population and the subsequent assumption made to assess their intake levels. Given the definition of AI, no conclusion on the adequacy of choline intake can be drawn for most European population groups. Such results improve the knowledge on choline intake in Europe that could be further refined by the collection of choline composition data for foods as consumed in Europe.
During neutron irradiation in nuclear power plants, uranium dioxide (UO2), the most used nuclear fuel, changes gradually its chemical composition because of the incorporation of new chemical elements which are created by fissions and named Fission Products (FP). As a consequence, the fluorine-type crystalline structure and its lattice parameters may also be modified. In order to better understand this behavior, neodymium-doped UO2 ceramics have been prepared with the aim to simulate the crystallographic matrix of irradiated fuels, since Nd is one of the most abundant FP. In a previous work, high temperature X-ray diffraction was performed on a sample (U0.72Nd0.28)O2, annealed under reducing conditions. The diffractograms evidenced, for the first time, the existence of a miscibility gap in the U-Nd-O system.
In this paper, we present the first results of a thermodynamic modeling of the ternary system U-Nd-O based on the CAlculation of PHAse Diagrams (CALPHAD) method, in order to obtain a complete description of this miscibility gap. The very first results of this modeling seem to confirm the presence of a region presenting two FCC (fluorite) phases (instead of a single solid solution, which is expected from literature). At room temperature, the gap appears from a Nd content as small as about 0.02 at. % and an O/M ratio slightly lower than 2.
Breast cancer metastasis to bone continues to be a major clinical problem, and patient-to-patient variability in rates of disease progression and metastasis complicate treatment even further. This may be due to differences in the cancer cells, the osteoclasts, or the pre-metastatic niche, but all of these contribute to proteolytic remodeling necessary for osteolytic lesion establishment, primarily through secretion of cathepsin K, the most powerful human collagenase. There is debate about the relative contributions of breast cancer cells and osteoclasts and synergism between the two in altering the biochemical and biomechanical properties of the colonized bone, as these are difficult to parse with animal models. To quantify the relative contributions of breast cancer cells and osteoclasts in bone resorption, we have been developing engineered bone microenvironment tissue surrogates by adapting a poly(ester urethane) urea system embedded with microbone particles. Here, we report their use with MDA-MB-231 breast cancer cells and RAW264.7 derived osteoclasts, to provide temporal, multiscale reporters of bone resorption that can be measured non-destructively: 1) collagen degradation measured by C-terminal collagen fragment release, 2) mineral dissolution by measuring calcium released with the calcium arsenazo assay, and also show their beneficial effects in upregulating cathepsin K expression compared to tissue culture polystyrene controls. These more natural derived bone surrogates may be useful tools in mimicking bone metastatic niche and determining differences between proteolytic activity of different patients’ tumor and bone resident cells in a controlled manner.
Many sea cucumber fisheries have dramatically declined worldwide due to rapid overexploitation and ineffective management. This study designed an innovative management strategy for small-scale, data-limited sea cucumber fisheries in Pacific Island countries. Firstly, a local quota-based comanagement system was implemented in New Caledonia to manage a small-scale sandfish Holothuria scabra fishery. A habitat map derived from high-resolution satellite imagery was used to stratify survey sampling and assess the harvestable stock biomass. The latter has been monitored as the reference biomass (RB) since 2008 and repeatedly used by the local fishers’ organization and Fisheries Department officers to set adaptive total allowable catches and regulations of fishing effort. Results showed the excellent performance of this fishery between 2008 and 2012, both biologically (167% increase in total stock biomass) and economically (146% increase in annual returns from catches). Secondly, the assessment of the RB was generalized to multispecies sea cucumber fisheries in Vanuatu in 2011 before the proposed lifting of a five-year national moratorium. Building upon these practical case studies in New Caledonia and Vanuatu, this paper outlines an operational framework to inform sea cucumber fisheries policy in these two countries and discusses the upscaling of the proposed management strategy.
An enormous effort is underway worldwide to attempt to detect gravitational waves. If successful, this will open a new frontier in astronomy. An essential portion of this effort is being carried out in Australia by the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA), with research teams working at the Australia National University, University of Western Australia, and University of Adelaide involving scientists and students representing many more institutions and nations. ACIGA is developing ultrastable high-power continuous-wave lasers for the next generation interferometric gravity wave detectors; researching the problems associated with high optical power in resonant cavities; opening frontiers in advanced interferometry configurations, quantum optics, and signal extraction; and is the world's leader in high-performance vibration isolation and suspension design. ACIGA has also been active in theoretical research and modelling of potential astronomical gravitational wave sources, and in developing data analysis detection algorithms. ACIGA has opened a research facility north of Perth, Western Australia, which will be the culmination of these efforts. This paper briefly reviews ACIGA's research activities and the prospects for gravitational wave astronomy in the southern hemisphere.
We present an overview of the latest results from the PdBI Arcsecond Whirlpool Survey (PAWS, PI: E. Schinnerer), which has mapped CO(1-0) emission in the nearby grand-design spiral galaxy M51 at 40pc resolution. Our data are sensitive to GMCs above 105 M⊙, allowing the construction of the largest GMC catalog to date – containing over 1500 objects – using the CPROPS algorithm (Rosolowsky & Leroy 2006). In the inner disk of M51, the properties of the CO emission show significant variation that can be linked to the dynamical environment in which the molecular gas is located. We find that dynamically distinct regions host clouds with different properties and exhibit different GMC mass spectra, as well as distinct patterns of star formation. To understand how this sensitivity to environment emerges, we consider the role of pressure on GMC stabilization (including shear and star formation feedback-driven turbulence). We suggest that, in the presence of significant external pressure, streaming motions driven by the spiral arm can act to reduce the surface pressure on clouds. The resulting stabilization impacts the global pattern of star formation and can account for the observed non-monotonic radial dependence of the gas depletion time. Our findings have implications for the observed scatter in the standard GMC relations and extragalactic star formation laws.
D. G. Blair, University of Western Australia, Perth,E. J. Howell, University of Western Australia, Perth,L. Ju, University of Western Australia, Perth,C. Zhao, University of Western Australia, Perth
The suppression of seismic ground motion is a significant challenge for ground based gravitational wave interferometric detectors. It is generally achieved through different combinations of active isolation and passive isolation. This chapter will look at two different vibration isolation systems. Part 1 will describe the mostly active vibration isolation system used by LIGO. Part 2 will discuss the mostly passive isolation systems developed at the University of Western Australia, which have features in common with isolation systems developed for many other detectors.
Seismic isolation for Advanced LIGO
Lantz for the LIGO Scientific Collaboration
One of the most significant improvements for Advanced LIGO will be to move the lower edge of the detection band from 40 Hz down to 10 Hz. This will allow us to start tracking the final inspiral of compact binary systems earlier in their evolution, and will also allow us to observe the inspirals not only of pairs of neutron stars, but also of binary systems containing more massive objects, such as black holes with 10 to 30 times the mass of the Sun, as described in Chapter 4. In order to measure gravitational waves at 10 Hz, the requirements for the motion of the Advanced LIGO mirrors are very strict. The Advanced LIGO interferometer cannot distinguish between differential length changes in the arms caused by the spacetime distortion of a passing gravitational wave and differential length changes caused by mirror motion. For an interesting discussion about interferometer configurations where this might not be true, see recent work by Kawamura and Chen (2004) and others.
Le comportement mécanique et la tenue en fatigue sont étudiés en fonction de
l’orientation des fibres et en fonction du chargement (traction-torsion) pour un
thermoplastique renforcé par des fibres de verre courtes. Les résultats présentent une
forte anisotropie qui exige la mise en œuvre d’une chaîne de dimensionnement qui intègre
la simulation du procédé : simulation de l’orientation des fibres par Moldflow, estimation
du comportement mécanique par homogénéisation de type Mori Tanaka et enfin application
d’un critère énergétique. La confrontation entre les résultats expérimentaux et cette
modélisation complète est très satisfaisante.
The effect of furnace grown SiO2 layers on the optical properties of p- on p+ (100) Si substrates are investigated. The real part, n, of the complex refractive index n* = n + ik is calculated for radiation measured in the infra-red (IR) region between 3000 and 8000 cm−1 where the extinction coefficient, k, is negligible. The expression for n is obtained using the Fresnel coefficients for a three medium air-oxide-Si model. Strain in the silicon, which affects n, and caused by the stress in the SiO2 layer, increases with oxide thickness. X-ray diffraction (XRD) was used to measure the strain in Si for oxides layers ranging from native to 5124Å. The data showed a monotonically increasing normal compressive strain, εN (up to 0.47%) with oxide thickness, however, the corresponding change in n due to strain was not well defined. The effect of strain on the direct optical gap, Ed, at 3.46 eV when determined from results of other investigators by electroreflectance, suggests an average shift in Ed of about 25 meV.
We have measured the photovoltaic spectra at 300K for a PIN GaAs/AlGaAs structure containing five coupled wells (50A/28A) grown by molecular beam epitaxy (MBE). The spectra were obtained in the energy range from 1.40 eV to 1.60 eV. This is the region in which optical transitions between the sub-band valence and conduction states are possible. Five direct optical transitions are allowed for this structure. These transitions are normally difficult to measure at room temperature because of broadening, nevertheless, some of the allowed transitions were observed from the photovoltaic spectra and agreed with calculations. We have previously shown that measurements made using electroreflectance (ER) agree with these results. However, with ER, three possible transitions were observed but only one with certainty, possibly because of interference caused by adjacent line spectra interaction. This interference appears to be less pronounced in the photovoltaic spectra, which aids in the identification of transitions.
In this paper, we develop a new method based on ultra-low-energy ion implantation through a stencil mask to locally fabricate Si nanocrystals in an ultrathin silica layer. We perform a 1 keV Si implantation with doses of 5×1015 Si+/cm2, 7.5×1015 Si+/cm2 and 1×1016 Si+/cm2 in a 7 nm thick silicon oxide layer through stencil mask apertures ranging from 1μm up to 5 μm. After the mask removal the samples are furnace annealed at a temperature of 1050°C for 90 min under N2 atmosphere. The samples are then characterized by mapping the implanted and non-implanted areas by atomic force microscopy and photoluminescence spectroscopy. The intensity and the wavelength of the PL peak are found to depend on the implanted NCs cell size. A slight blue shift from 730 nm up to 720 nm is observed with decreasing cell size. Simultaneously, the PL intensity decreases and the signal vanishes for submicron features (which should contain 102 to 103 NCs). AFM microcopy performed on the implanted regions shows that the well-known oxide swelling usually observed after NCs synthesis decreases from 3.5 nm down to 0 as the cell size decreases. This result demonstrates that the effective implanted dose clearly decreases with the size of the cells. This effect is probably due to an electrostatic charging of the Si3N4 membrane despite the metallization treatments applied to the mask surface.
A multistate outbreak of Escherichia coli O157:H7 infections occurred in the USA in November–December 2006 in patrons of restaurant chain A. We identified 77 cases with chain A exposure in four states – Delaware, New Jersey, New York, and Pennsylvania. Fifty-one (66%) patients were hospitalized, and seven (9%) developed haemolytic uraemic syndrome; none died. In a matched analysis controlling for age in 31 cases and 55 controls, illness was associated with consumption of shredded iceberg lettuce [matched odds ratio (mOR) 8·0, 95% confidence interval (CI) 1·1–348·1] and shredded cheddar cheese (mOR 6·2, CI 1·7–33·7). Lettuce, an uncooked ingredient, was more commonly consumed (97% of patients) than cheddar cheese (84%) and a single source supplied all affected restaurants. A single source of cheese could not explain the regional distribution of outbreak cases. The outbreak highlights challenges in conducting rapid multistate investigations and the importance of incorporating epidemiological study results with other investigative findings.
Tight binaries discovered in young nearby associations are ideal targets to provide dynamical mass measurments through orbital monitoring. Coupled with estimated temperatures, surface gravities and luminosities, direct mass measurments provide benchmarks for evolutionary models of low-mass stars (M ≤ 0.5 M๏) and brown dwarfs (M ≤ 0.078 M๏) at young ages (Age ≤ 100 Myrs).
TWA22 AB is likely to be a member of the nearby TW Hydrae association (Age ~ 8 Myr). It was resolved in a tigh binary with a projected separation of a few AU. In this paper we present preliminary results on the companion orbital monitoring and on the spectral characterisation of the system.
Serological markers and peak serum alanine aminotransferase (ALT) values of 140 in-patients with acute hepatitis, either type A (n = 90), or type B (n = 50) were prospectively assessed. In 23 out of the 90 patients with acute hepatitis A, evidence of previous experience with hepatitis B virus (HBV) was found, whereas 35 out of the 50 patients with acute hepatitis B had past contact with hepatitis A virus (HAV). The mean peak ALT values [S.D.] were significantly higher in hepatitis A patients with previous experience with HBV (1413  i.u./l), when compared to those without such experience (842  i.u./l, P < 0·001). Such a difference was not evident between acute hepatitis B patients, whether or not they had previous contact with HAV. We conclude that when acute hepatitis A is superimposed on past HBV infection an augmented transaminaemia, indicative of enhanced liver cell necrosis, takes place although a definite explanation is lacking. We suggest that individuals with markers of HBV infection should be early candidates for HAV immunization.
We have solved to 3.3 Å resolution the crystal
structure of the HIV reverse-transcription primer tRNA(Lys,3).
The overall structure is exactly comparable to the well-known
L-shape structure first revealed by yeast tRNA(Phe). In
particular, it unambiguously shows a canonical anticodon
loop. This contradicts previous results in short RNA
fragment studies and leads us to conclude that neither
frameshifting specificities of tRNA(Lys) nor tRNA(Lys,3)
primer selection by HIV are due to a specific three-dimensional
anticodon structure. Comparison of our structure with the
results of an NMR study on a hairpin representing a
nonmodified anticodon stem-loop makes plausible the conclusion
that chemical modifications of the wobble base U34 to
5-methoxycarbonyl-methyl-2-thiouridine and of A37 to
would be responsible for a canonical 7-nt anticodon-loop
structure, whereas the unmodified form would result in
a noncanonical UUU short triloop. The hexagonal crystal
packing is remarkable and shows tight dimers of tRNAs forming
a right-handed double superhelix. Within the dimers, the
tRNAs are associated head-to-tail such that the CCA end
of one tRNA interacts with the anticodon of the symmetry-related
tRNA. This provides us with a partial view of a codon–anticodon
interaction and gives insights into the positioning of
residue 37, and of its posttranscriptional modifications,
relative to the first base of the codon.
Maize is a flowering plant well suited for biological research on reproduction processes. In addition to interesting sexual traits, there is in this species a large amount of data regarding genetics and cytogenetics. The embryo sac and the female germ unit have been characterized, and precise studies have been developed on male gametes. Finally, the time course of double fertilization has recently been determined. Nevertheless, the intimate mechanisms of double fertilization are still unknown. A new way to approach this phenomenon is to develop systems of “in vitro fertilization.” In this chapter, the technical procedures to isolate and manipulate male and female gametes in maize are described. The embryo sac and egg cells are prepared with the help of an enzymatic treatment. Sperm cells or male nuclei from viable pollen grains are released in an acidic medium and selected from a specific layer of a Percoll gradient after centrifugation steps. With these cellular tools, two in vitro methods of fertilization have been developed: (1) spontaneous fusion of male and female gametes in the presence of 5 mM of calcium and (2) microinjection of male nuclei either into the egg or into the central cell of a mature embryo sac. Culture of the artificial zygotes and microinjected embryo sacs is in progress. All these techniques provide a new window for investigating the first steps of fertilization and early embryogenesis at the cellular and molecular levels.
Camerarius (1694, reviewed in Ducker and Knox 1985) was the pioneer in plant reproductive biology.
Isolates of Cylindrocladium floridanum obtained from diseased
roots of white and black spruce seedlings and surrounding soil in
bareroot nurseries in Ontario, Minnesota and Wisconsin area were compared
mitochondrial DNA (mtDNA) and ribosomal DNA
(rDNA) restriction fragment length polymorphisms (RFLPs), human minisatellite
DNA fingerprints and polymerase chain reaction.
Nucleotide sequences of rDNA ITS regions of selected isolates were also
Based on the nuclear DNA fingerprinting
patterns, these isolates could be divided into three groups, namely S1,
S3. Isolates of S1 and S2 showed the same
mtDNA RFLPs which were slightly different from that of S3. Isolates representing
each of the three groups showed an identical
nucleotide sequence of rDNA ITS regions. These data suggest that all the
tested belong to the same species which may be
divided into three biotypes or populations.
Artificial fertilisation was attempted in maize by microinjecting sperm nuclei into the egg cell or central cell of isolated embryo sacs. A protocol for isolation of nuclei from pollen grains was developed and a pure fraction of sperm nuclei was obtained after centrifugation on a Percoll gradient. The in vitro transcriptional activity of the nuclei was tested by incorporation of radioactive UTP into RNA. The level of labelled nucleotide incorporation increased and reached a maximum after between 30 and 40 min in the incubation medium. The embryo sacs were enzymatically isolated and their viability determined by observation of cytoplasmic streaming in the female cells. The embryo sacs were immobilised by embedding in low-melting-point agarose and a single male nucleus was injected with a bevelled microcapillary. The presence of the injected nucleus in the egg or central cell was demonstrated using a cytological approach. This paper presents an alternative method for studying the intimate processes of fertilisation in plants.