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.
Multi-stakeholder initiatives (MSIs) have emerged as a leading institutional approach for advancing sustainability globally. This paper examines three prominent MSIs that have developed sustainability metrics and a standard for US agriculture: Field to Market, the Stewardship Index for Specialty Crops and the National Sustainable Agricultural Standard Initiative. Using data from interviews and content analysis of initiative reports, two sets of analyses are presented. First, building on Paul Thompson's tri-partite theorization of sustainability, how each initiative is conceptualizing agricultural sustainability is analyzed. We find that two contrasting visions of sustainable agriculture for the USA have emerged from the three MSIs. One vision is a resource sufficiency approach focused on eco-efficiencies and the other vision is a functional integrity approach that emphasizes the maintenance of resilient agricultural and ecological systems. Second, we examine the governance practices of the MSIs to explain why such divergent conceptualizations of sustainability have been mapped out. We find that far from being a neutral forum, the internal dynamics of MSIs often reflect and reproduce existing power relationships among stakeholders. In concluding, we suggest that incremental improvements in sustainability can be achieved using MSIs, but more transformative changes may require other forms of governance.
For the improvement of the orbital elements of Hyperion, a program of photographic observations of Saturnian satellites has been made since the opposition of 1966. In this paper are presented the reduction method and results derived from the observations during the oppositions of 1968 and 1977.
The polarization observation of solar radio emission at 200 Mc./s. was started in December 1954 at the Tokyo Astronomical Observatory with a new type of radio polarimeter[1, 2]. With a pair of crossed dipoles at the focus of a 10 metre paraboloid of equatorial mounting, it gives almost simultaneously six components of polarization, two circular and four linear, on a time-sharing basis by using electronic switching. Fig. 1 shows the block diagram of the circuit and the combination of modulators and demodulators. 6AS6 pentodes are used as the time modulators. The duration of each gate pulse is 1/1600 sec. and one set of observations is obtained in 1/200 sec. One of the principal features of the present scheme is to use a common receiving system for all the components in order to avoid inevitable errors due to differences or changes in the gain and in the central frequencies of different receivers. A new type of square-law detector is employed in the present system . It has rapid response time and excellent stability.
The partial solar eclipse of 20 June 1955 was observed at Tokyo and Toyokawa, where regular solar radio observations are conducted. A party was sent to Kagoshima by the Tokyo Astronomical Observatory. The locations, the frequencies observed and the types of aerial are listed in Table 1. The paths of the northern limb of the moon at three stations are shown by dotted lines in Fig. 3.
To evaluate the growth of children after repair of Tetralogy of Fallot, as well as the influence of residual lesions and socio-economic status.
A total of 17 children, including 10 boys with a median age of 16 months at surgery, were enrolled in a retrospective cohort, in a tertiary care university hospital. Anthropometric (as z-scores), clinical, nutritional, and social data were collected.
Weight-for-age and weight-for-height z-scores decreased pre-operatively and recovered post-operatively in almost all patients, most markedly weight for age. Weight-for-height z-scores improved, but were still lower than birth values in the long term. Long-term height-for-age z-scores were higher than those at birth, surgery, and 3 months post-operatively. Most patients showed catch-up growth for height for age (70%), weight for age (82%), and weight for height (70%). Post-operative residual lesions (76%) influenced weight-for-age z-scores. Despite the fact that most patients (70%) were from low-income families, energy intake was above the estimated requirement for age and gender in all but one patient. There was no influence of socio-economic status on pre- and post-operative growth. Bone age was delayed and long-term-predicted height was within mid-parental height limits in 16 children (93%).
Children submitted to Tetralogy of Fallot repair had pre-operative acute growth restriction and showed post-operative catch-up growth for weight and height. Acute growth restriction could still be present in the long term.
Cementitious materials have been studied for their applicability as support and lining in the construction of shafts and tunnels of the underground facilities for HLW disposal system. However, in the case of Ordinary Portland Cement (OPC), the buffer materials and the host rock may be altered due to the high alkalinity of groundwater contacting the OPC in the long-term. Low alkaline cements with high content of pozzolanic material were developed in order to reduce such hyper alkaline alteration. This paper shows that the pH of the leaching solution of this cement is about 11, and that it can be applied for full scale lining and for shotcrete.
TiOx thin films were prepared from titanium tetraisopropoxide (Ti-(O-i-C3H7)4, TTIP) in a remote plasma enhanced chemical vapor deposition (RPE-CVD) using a mixture of hydrogen/oxygen plasma gas. Emission spectra suggested that H-radicals dissociated TTIP molecules in gas phase. By mixing with oxygen, H-radical density was increased with the correlation effect to result in enhancement of deposition rate. Deposition rate was also influenced by OH-radicals. OH-radicals caused deactivation of precursors and hence suppressed Ti-O-Ti bond formation in gas phase. The highest deposition rate of 11 nm/min, which was two orders higher than that for the case of single gas plasma, was achieved in the case of mixture gas ratio of 20% oxygen and 80% hydrogen. Surface reaction due to the heated substrate did not affect the deposition rate though the film structure was remarkably changed. It was demonstrated that for RPE-CVD process, oxygen/hydrogen mixture gas plasma was effective for obtaining high deposition rate, and also H-to-OH radical density ratio was an important factor to control the deposition rate.
ZnO and SiO2 thin films coated on plastic materials were investigated for the protection against solar ultraviolet (UV) radiation and the hard coating. Using diethylzinc (DEZ) as the organic zinc material, we attempt to deposit ZnO thin films on polycarbonate (PC) resin at room temperature by the cathode deposition technique of the plasma enhanced (PE) CVD method. It was found that the rf power and the substrate temperature intensively influenced on the deposition rate. The deposition rate increased with the rf power up to 100W, but decreased with the RF power above 100W, and also decreased with increasing the substrate temperature. In a xenon arc weatherability test, the ZnO-coated PC plates exhibited remarkable protection characteristics against UV radiation. They kept a smooth surface and no- coloring even if UV light irradiated for 1000 hours. Moreover, SiO2film deposited from tetraethoxysilane (TEOS) was over-coated on the ZnO film / PC plates. These films showed a drastic improvement in the hardness. Therefore, these films are expected as the UV-cut and hard coating for the automotive parts.
The effects of dopant type and dopant concentration on the native oxide growth in air on the silicon surface were investigated. The oxide thickness was measured by X-ray photoelectron spectrometry (XPS). The oxide was thicker on n-type Si than on p-type Si in early oxidation. The oxide increased linearly with the dopant concentration. This enhancement of oxidation was assumed to be caused by vacancies near the surface in the silicon bulk.
SiO2 thin firms were fabricated in a remote electron cyclotron resonance (ECR) plasma by tctraethoxysilane (TEOS) as the silicon source. Oxygen was used as the plasma gas. A mesh was placed between the TEOS gas outlet and the substrate. In the present investigation a-SiO2 films were deposited with and without the mesh and film properties were studied comparatively. The deposition rate increased when the mesh was attached. The optimum deposition rate is observed when the mesh voltage was zero, that is the mesh was grounded. The deposition rates of both methods were also dependnt on the TEOS flow rate, applied microwave power and the substrate temperature. These three parameters have significant roles in controlling the film quality. Good quality SiO2 films can be obtained with a higher deposition rate when a mesh is attached.
detailed study was carried out in investigating the chemical reaction scheme involved with the deposition of a-SiC:H films by carbosilane sources in a remote hydrogen plasma. As the carbosilane sources, tetramethylsilane (TMS), hexamethyldisilane (HMDS) and tetrakis(trimethylsilyl)silane (TMSS) were used. Depositions were performed in the presence and absence of both UV radiation and H radicals. UV radiation activates only the TMS molecules out of the above three types of molecules in depositing a-SiC:H films. Other two monomers are seen to be activated by hydrogen radicals. It is proposed that the most susceptible bond to be broken at first by hydrogen radical is the Si-Si bond. A reaction model for the formation of a- SiC:H films was presented by considering the Me2Si=CH2 as the film forming precursor.
Polycrystalline silicon (poly-Si) films are of great interest in the field of TFT fabrication for active matrix liquid crystal display(AM-LCD) applications. Low temperature depositions below 500 °C are necessary for using a glass substrate for the application to large area devices such as display devices. We investigated poly-Si growth at low temperature by plasma enhanced chemical vapor deposition (PECVD). Cathode deposition is used in which substrates are mounted on the powered electrode and a mesh electrode is attached on the cathode for protecting the growing surface from ion impacts. It is found that poly-Si films can be deposited in the wide range of SiH4 concentration even at 100%, and a high deposition rate of 35nm/min has been realized. This investigation gives highly promising results for poly-Si growth technology at low temperature.
In performance assessment of geological disposal systems the phenomenon of dispersion in geological media is one of the most important processes to be modeled and is dependent on the heterogeneity of the media. In order to understand the dispersion process in a well defined heterogeneous field, laboratory experimental apparatus, named MACRO, was constructed to study fluid flow and mass transport. A synthetic heterogeneous field was constructed in a flow-bed using six kinds of glass beads with diameters of 0.1, 0.15, 0.2, 0.4, 0.6 and 0.8 mm. Both dye (brilliant blue) and NaCI solution were used as tracers in the experiment. A particle tracking method, considering advection, was used in numerical simulations of the experiment, and the dispersion effect was assumed to be expressed by the variability of the local advective velocity in a high resolution numerical grid. The simulated results obtained by the particle tracking method agreed with the measurement, confirming the applicability of modelling approach used in this study.
The long-term programme of in-situ radionuclide migration experiments in the underground test site at Grimsel (GTS) involves the development and testing of radionuclide transport models with their associated databases. The field experiments are carried out in a water-bearing shear zone in crystalline rock utilising a suite of tracers of differing geochemical behaviour. A rigorous model testing procedure has been developed for the GTS radionuclide migration experiment. This paper describes application of this testing procedure to a solute transport code developed by PNC.
A study of laser annealing of a-SiC:H films was carried out in order to obtain poly-SiC films. First, a-SiC:H films were fabricated at temperatures ranging from 30 to 400 °C. All these films show amorphous structure before the annealing process. After annealing by a single pulse of 248 nm laser, films show poly-SiC structure. The pulse energies used for these anneals varied from 30 to 300 mJ/pulse. After exposing to a laser pulse, the a-SiC:H films melt and recrystallize forming poly-SiC structure. In addition to this process, a fraction of the film is observed to be vaporized. This vaporized fraction depends on the original film composition, hardness and the laser pulse-energy. Electrical resistivity of the films before the annealing process lies in the region of 1015 Ωcm. This resistivity drops drastically after the annealing process.
This paper describes an approach for assessing the geosphere performance of nuclear waste disposal in fractured rock. In this approach, a three-dimensional heterogeneous channelnetwork model is constructed using a stochastic discrete fracture network (DFN) code. Radionuclide migration in the channel-network model is solved using the Laplace transform Galerkin finite element method, taking into account advection-dispersion in a fracture network, matrix diffusion, sorption in the rock matrix as well as radioactive chain decay. Preliminary radionuclide migration analysis was performed for fifty realizations of a synthetic block-scale DFN model. The total radionuclide release from all packages in the repository was estimated from the statistics of the results of fifty realizations under the hypothesis of ergodicity. The interpretation of the result of the three-dimensional network model by a combination of simpler one-dimensional parallel plate models is also discussed.
n-and p-type doping of CdTe grown heteroepitaxially on GaAs substrate by radical assisted metal organic chemical vapor deposition technique were studied. n-type doping was studied by the gas phase n-butyliodine doping during the film growth, whereas p-type doping was carried by treating the undoped layers with alkaline metal compound (Na2Te) and excimer laser radiation. Highly conductive n-and p-layers were thus obtained which formed good ohmic contact with aluminum and gold electrodes, respectively. Using this technique, n-and p- layers were formed on intrinsic CdTe substrate to form p-i-n diode. This p-i-n structure showed a good diode characteristics and good sensitivity to X-ray radiation with dark current in the order of nA/mm 2 at room temperature.
An organosilicon compound, hexamethyldisilane (HMDS) was incorporated for SiC thin film preparation by remote plasma enhanced CVD method. We investigated how plasma excited radicals react with source monomers using two kinds of gas mixtures. It was found that film component and formation mechanism depends on stronger on plasma gases. Using a mixture of nitrogen and hydrogen gases as plasma gas source, deposited films contained large amounts of nitrogen. When uing an argon and hydrogen mixture, deposited film was a SiC with large hydrogen contents. In this research, we found that hydrogen radicals are very active for decomposition of monomer source gas and this can be related to precursors for film deposition. When using a mixture of argon and hydrogen as plasma gas, the film deposition speed was influenced by substrate temperature. The estimated activation energy was larger than the case of using nitrogen and hydrogen gases. Different reaction mechanisms were observed for different plasma gas source
For epitaxial growth of compound Zn1−xCd1−XTe by metal organic chemical vapor deposition (MOCVD), it is difficult to obtain a high composition ratio x. In this study, we have adopted a remote plasma enhanced (RPE) MOCVD method for the epitaxial growth. Cd1−xZnxTe with the composition ratio x in the range of 0 to 1 has been obtained while varying the ratio of dimethylcadmium (DMCd) to diethylzinc (DEZn) from 0 to 20%. The crystallinity of the epitaxial films was about 400 to 700 arcsec FWHM defined by X ray diffiraction measurements.
SiO2 thin films were deposited on automobile plastics at low temperatures using a microwave activated ECR plasma. Oxygen was used as the plasma gas while tetraethoxysilane (TEOS) was used as the source gas which was introduced into the downstream. In the present investigation high quality SiO2 films were deposited on polycarbonate (PC) and polypropylene (PP) substrates with and without a mesh and the characteristics of hard coating films were studied. The film growth rate increases with the decrease of substrate temperature when a mesh is inserted into the plasma. The irregularities of polymer surfaces could be planarized by the deposition of 1.0 μm thick SiO2 film. The dynamic hardness of PC and PP are increased by the deposition of SiO2 film, however, films deposited on PP is seen to be cracked while that of on PC is crack-free.