20 research outputs found
Design of a 3µm pixel linear CMOS sensor for earth observation
No full textA visible wavelength linear photosensor featuring a pixel size of 3µm has been designed for fabrication using commercial 0.25µm CMOS technology. For the photo-sensing element, the design uses a special "deep N-well" in P-epi diode offered by the foundry for imaging devices. Pixel reset is via an adjacent p-FET, thus allowing high reset voltages for a wide pixel voltage swing. The pixel voltage is buffered using a voltage-follower op-amp and a sampling scheme is used to allow correlated double sampling (CDS) for removal of reset noise. Reset and signal levels are buffered through a 16:1 multiplexer to a switched capacitor amplifier which performs the CDS function. Incorporated in the CDS circuit is a programmable gain of 1-8 for increased signal-to-noise ratio at low signal levels. Data output is via 4 analogue output drivers for off-chip conversion. Each driver supplies a differential output voltage with a ± 1V swing for 6.25kHz. This gives a peak data rate at each output driver of 10M sample/s. The device will operate on a 3.3V supply and will dissipate approximately 950mW. Simulations indicate an equivalent noise charge at the pixel of 66.3e- for a full well capacity of 255,000e-, giving a dynamic range of 71.7dB
A new superconductor in lead cuprate (Pb0.5B0.5)Sr-2(Y0.5Ca0.5)Cu2Py
No full textA new lead cuprate superconductor, (Pb0.5Ba0.5)Sr-2(Y0.5Ca0.5)Cu2Oy, With T-c(onset)=62 K and T-c(zero)=31 K, has been prepared. Barium ions occupy the part sites of the lead in the unit cell. The crystal parameters of this superconductor are a=3.82 Angstrom, c=11.93 Angstrom. For one of the samples, an anomalous drop of resistance was observed around 230 K, but it disappeared after 4 thermocycles.Physics, AppliedSCI(E)EI
Cosmological parameter estimation using Very Small Array data out to ℓ= 1500
No full textWe estimate cosmological parameters using data obtained by the Very Small Array (VSA) in its extended configuration, in conjunction with a variety of other cosmic microwave background (CMB) data and external priors. Within the flat Λ cold dark matter (ΛCDM) model, we find that the inclusion of high-resolution data from the VSA modifies the limits on the cosmological parameters as compared to those suggested by the Wilkinson Microwave Anisotropy Probe (WMAP) alone, while still remaining compatible with their estimates. We find that Ωbh2= 0.0234+0.0012−0.0014, Ωdmh2= 0.111+0.014−0.016, h= 0.73+0.09−0.05, nS= 0.97+0.06−0.03, 1010AS= 23+7−3 and τ= 0.14+0.14−0.07 for WMAP and VSA when no external prior is included. On extending the model to include a running spectral index of density fluctuations, we find that the inclusion of VSA data leads to a negative running at a level of more than 95 per cent confidence ( nrun=−0.069 ± 0.032 ), something that is not significantly changed by the inclusion of a stringent prior on the Hubble constant. Inclusion of prior information from the 2dF galaxy redshift survey reduces the significance of the result by constraining the value of Ωm. We discuss the veracity of this result in the context of various systematic effects and also a broken spectral index model. We also constrain the fraction of neutrinos and find that fν < 0.087 at 95 per cent confidence, which corresponds to mν < 0.32 eV when all neutrino masses are equal. Finally, we consider the global best fit within a general cosmological model with 12 parameters and find consistency with other analyses available in the literature. The evidence for nrun < 0 is only marginal within this model
Implementation fidelity of circularity in publicly tendered civil engineering projects
No full textWith the current urgency to become more circular, procurement presents the primary method to deliver the circular policy ambition by purchasing circular products and stimulating circularity in the market. In the building and infrastructure sector, civil engineering projects offer unique opportunities for circularity. This research presents an assessment of the implementation fidelity of the circular ambition within the tendering process. It examines for each of the methods that define the tendering process, the tendered project, and the awarding framework whether the way circularity is being implemented delivers the ambition as expected.Along with the four research phases, the research devises and uses a framework to assess the fidelity of circularity implementation through the methods to include it in the tendering of civil engineering works. The implementation fidelity framework is used to; create a holistic analysis that captures the many facets impacting the tendering process; determine areas of issues and, consequently, room for improvements; and differentiate between the methods to include the circular ambition in the process. Through three study cases, the construct of the analysis managed to capture the data between quantitative and qualitative in a consistent and interpretable manner. It creates a consistent link between the fidelity dimensions, the corresponding issue areas, and the methods to include circularity in the tendering process. The room for improvement follows the three moderating dimensions, exposure, quality of delivery, and participation. The research links the issues impacting the fidelity of circular ambition implementation in three categories: structural issues, implementation traps, and policy-related, to the three moderating dimensions. The research acknowledges that policy-related issues impact at a sector level as issues inherent to the policy itself. Nonetheless, the research finds that, on an organizational level, removing structural issues and implementation traps raises overall fidelity and reduces the effect of policy-related issues. Increasing this fidelity reflects on the efficacy of the methods to include circularity in tendering, individually and as a group of instruments intended to complement each other. In conclusion, the research recommends practical use of the implementation fidelity framework, which would feed into the body of expertise within an organization to improve future tendering processes to include, enable, and produce more circular solutions with more efficacy in the use of the methods. It will also allow aligning perceptions of the contractors and the contracting authority on one hand and the policymakers and policy implementers on the other hand. For future research, examining all five implementation fidelity dimensions for the instruments and processes at the different levels throughout the procurement cycle is most compatible with the circular ambition in the building and infrastructure sector. This could be most beneficial to establish a more vital link between policymakers and policy implementers. Moreover, it would support future efforts to update the circular ambition goals and milestones by presenting a more encompassing image of the policy implementation fidelity in real-world settings.Civil Engineering | Construction Management and Engineerin
Dynamic study of oxygen in Cu-O plane in Bi-system superconductors
No full textSuperconducting transition temperature (T-c), hole concentration (n(c)), and crystal structure for Bi1.7Pb0.3Sr2Ca2Cu3Oy (2223) polycrystals and Bi2Sr2CaCu2Oy (2212) single crystals annealed in different atmospheres have been measured. It is found that the consequence of annealing in O-2 is mainly the modification of the oxygen in Cu-O planes, which is different from that in N-2 where the change is in the Bi-O planes. The result provides a good explanation for the complicated changes of the T-c with the annealing conditions.Physics, AppliedSCI(E)EI
Study of mismatch between two different blocks in Bi-system superconductors
No full textSamples of Bi1.7Pb0.3Sr2Ca2Cu3O10+y (2223) annealed in different atmospheres and having different value of T-c and oxygen contents were obtained and examined by a wide range of measurements as well as theoretical calculation. A roughly quantitative relationship among T-c, oxygen content, c direction thermal expansion coefficient, and mismatch factors are established. It is revealed that the mismatch is important for superconductivity.Physics, AppliedSCI(E)EI
An Opposite Behaviour of Semiconducting and Superconducting YBCO Single Crystal
No full textAn opposite thermal dynamic change in superconducting and semiconducting cuprates of YBa2Cu3O7−x(Y-123) is observed. At 450 °C the superconducting Y-123 single crystal shows an endothermal anomaly and a weight loss, while the semiconducting one shows an exothermal anomaly and weight gain. High temperature x-ray diffraction reveals that the lattice parameters of the Y-123 crystal jump significantly at this temperature. A computer simulation demonstrates that the change of the lattice parameters can be related with the change of the lattice energy
Preparation of superconducting HgBa(2)CaCu(2)Ox and Hg(0.8)Bi(0.2)Ba(2)CaCu(2)Ox films by means of annealing of mercury-free precursor films
No full textHgBa(2)CaCu(2)Ox films and Hg(0.8)Bi(0.2)Ba(2)CaCu(2)Ox films were prepared by means of annealing of mercury-free precursor films with the Hg-1212 bulks in an evacuated quartz tube. The mercury-free precursor films were deposited by laser ablation on (100) SrTiO3 substrates. The annealed films exhibited the (OOn) oriented X-ray diffraction pattern of the Hg-1212. The superconducting transition temperatures, T-c(p=0), are 121 K and 100 K respectively.Physics, AppliedSCI(E)EI
Anomalous Behaviour of Bi-System Superconductors in the Normal State and their Correlation with Superconductivity
No full textOur experiments show that Bi-system samples exhibit two parameter anomalies and two heat and weight anomalies in normal state. For the samples of (Bi,Pb)2Sr2CaCu2Oy, as the superconducting volume is over 65%, two anomalies of heat and weight at about 400 °C and 750 °C, respectively, are significantly observed; as the superconducting volume of the samples is under 50%, or the samples are non-superconducting, the anomaly at about 400 °C is hardly observed. For the samples of (Bi,Pb)2Sr2Ca2Cu3Oy, as the superconducting volume is over 65%, they exhibit two anomalies at about 300 °C and 750 °C, respectively; as the superconducting volume is under 50%, the anomaly at about 300 °C disappears, and as the samples are non-superconducting, it shows a quite opposite behavior to the superconducting samples at about 300 °C. We develop a computer program based on calculation of lattice energy to simulate the experimental results, it is found that the change of the lattice energy can well explain the anomalous phenomena in the samples
Gut colonisation by extended-spectrum beta-lactamase-producing Escherichia coli and its association with the gut microbiome and metabolome in Dutch adults: a matched case-control study
No full textBackground: Gut colonisation by extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli is a risk factor for developing overt infection. The gut microbiome can provide colonisation resistance against enteropathogens, but it remains unclear whether it confers resistance against ESBL-producing E coli. We aimed to identify a potential role of the microbiome in controlling colonisation by this antibiotic-resistant bacterium.Methods: For this matched case-control study, we used faeces from 2751 individuals in a Dutch cross-sectional population study (PIENTER-3) to culture ESBL-producing bacteria. Of these, we selected 49 samples that were positive for an ESBL-producing E coli (ESBL-positive) and negative for several variables known to affect microbiome composition. These samples were matched 1:1 to ESBL-negative samples on the basis of individuals' age, sex, having been abroad or not in the past 6 months, and ethnicity. Shotgun metagenomic sequencing was done and taxonomic species composition and functional annotations (ie, microbial metabolism and carbohydrate-active enzymes) were determined. Targeted quantitative metabolic profiling (proton nuclear magnetic resonance spectroscopy) was done to investigate metabolomic profiles and combinations of univariate (t test and Wilcoxon test), multivariate (principal coordinates analysis, permutational multivariate analysis of variance, and partial least-squares discriminant analysis) and machine-learning approaches (least absolute shrinkage and selection operator and random forests) were used to analyse all the molecular data.Findings: No differences in diversity parameters or in relative abundance were observed between ESBL-positive and ESBL-negative groups based on bacterial species-level composition. Machine-learning approaches using microbiota composition did not accurately predict ESBL status (area under the receiver operating characteristic curve [AUROC]=0.41) when using either microbiota composition or any of the functional profiles. The metabolome also did not differ between ESBL groups, as assessed by various methods including random forest (AUROC=0- 61).Interpretation: By combining multiomics and machine-learning approaches, we conclude that asymptomatic gut carriage of ESBL-producing E. coli is not associated with an altered microbiome composition or function. This finding might suggest that microbiome-mediated colonisation resistance against ESBL-producing E, coli is not as relevant as it is against other enteropathogens and antibiotic-resistant bacteria. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd.Proteomic
