Algorithms for FFT Beamforming Radio Interferometers

Radio interferometers consisting of identical antennas arranged on a regular lattice permit fast Fourier transform beamforming, which reduces the correlation cost from $\mathcal{O}(n^2)$ in the number of antennas to $\mathcal{O}(n\log n)$. We develop a formalism for describing this process and apply this formalism to derive a number of algorithms with a range of observational applications. These include algorithms for forming arbitrarily pointed tied-array beams from the regularly spaced Fourier-transform formed beams, sculpting the beams to suppress sidelobes while only losing percent-level sensitivity, and optimally estimating the position of a detected source from its observed brightness in the set of beams. We also discuss the effect that correlations in the visibility-space noise, due to cross-talk and sky contributions, have on the optimality of Fourier transform beamforming, showing that it does not strictly preserve the sky information of the $n^2$ correlation, even for an idealized array. Our results have applications to a number of upcoming interferometers, in particular the Canadian Hydrogen Intensity Mapping Experiment--Fast Radio Burst (CHIME/FRB) project.Comment: 17 pages, 4 figures, accepted to Ap

A review of the potential issues of pollution caused by the Mineral elements, Mercury, Lead and Arsenic, its possible impacts on the human beings and the suggested solutions

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2,3-Dibromo-3-phenyl­propionic acid

In the crystal of the title compound, C9H8Br2O2, inversion dimers linked by two O—H⋯O hydrogen bonds occur. All of the carbon and oxygen atoms are disordered over two sets of sites in a 2:1 ratio

Interaction between maize ribosome-inactivating protein and ribosomes

Poster Presentation: abstract no. A11Ribosome‐inactivating proteins (RIPs) represent a group of N‐glycosidases which can cleave the N‐glycosidic bond of adenine at 23S and 28S ribosomal RNA (rRNA) of ribosome and subsequently lead to a halt of protein synthesis and cell death. Regardless to the universal rRNA target, the highly conserved catalytic residues and consensus tertiary structure of RIPs, the activity of RIPs is highly deviated. It is known …postprin

Stability Analysis of Shafts Used for Minewater Heat Recovery

Traditional heating using non-renewable energy resources contributes up to 50% of current carbon emission level. Different sources of renewable energy are being exploited and developed to lower the carbon emission level for continuity of healthy living environment. It is found that thermal energy is stored in minewater flooding abandoned mines. The minewater can be extracted through newly drilled boreholes or existing mineshafts. To ensure successful and sustainable operation, mineshafts have to be structurally stable. When the mines are abandoned, the water level tends to recover. Some of the configurations of the minewater heat recovery may change the temperature of part of the shaft wall. This research aims to provide some insight on the stability of mineshafts for minewater heat recovery through numerical sensitivity analyses on: (a) water level, (b) temperature fluctuations. In the presented research work, rock masses with different properties have been analyzed. Change in temperature is found to mainly change the static Young’s Modulus of intact rock and the joint roughness. However, the joint roughness is expressed indirectly using the Geological Strength Index, which has direct relationship with joint roughness and is used in stability analysis. It is found that an increase in water level reduces the integrity of the whole shaft. The degrees of stability deterioration are different at different depths and depend on the in situ stress state. Findings of this analyses can be assist in making a decision on the selection of the appropriate configuration for minewater heat recovery

Towards an equitable digital society:artificial intelligence (AI) and corporate digital responsibility (CDR)

In the digital era, we witness the increasing use of artificial intelligence (AI) to solve problems, while improving productivity and efficiency. Yet, inevitably costs are involved with delegating power to algorithmically based systems, some of whose workings are opaque and unobservable and thus termed the “black box”. Central to understanding the “black box” is to acknowledge that the algorithm is not mendaciously undertaking this action; it is simply using the recombination afforded to scaled computable machine learning algorithms. But an algorithm with arbitrary precision can easily reconstruct those characteristics and make life-changing decisions, particularly in financial services (credit scoring, risk assessment, etc.), and it could be difficult to reconstruct, if this was done in a fair manner reflecting the values of society. If we permit AI to make life-changing decisions, what are the opportunity costs, data trade-offs, and implications for social, economic, technical, legal, and environmental systems? We find that over 160 ethical AI principles exist, advocating organisations to act responsibly to avoid causing digital societal harms. This maelstrom of guidance, none of which is compulsory, serves to confuse, as opposed to guide. We need to think carefully about how we implement these algorithms, the delegation of decisions and data usage, in the absence of human oversight and AI governance. The paper seeks to harmonise and align approaches, illustrating the opportunities and threats of AI, while raising awareness of Corporate Digital Responsibility (CDR) as a potential collaborative mechanism to demystify governance complexity and to establish an equitable digital society

Estimating the proportion of metabolic health outcomes attributable to obesity: a cross-sectional exploration of body mass index and waist circumference combinations

BACKGROUND: Recent evidence suggests that a substantial subgroup of the population who have a high-risk waist circumference (WC) do not have an obese body mass index (BMI). This study aimed to explore whether including those with a non-obese BMI but high risk WC as \u27obese\u27 improves prediction of adiposity-related metabolic outcomes. METHODS: Eleven thousand, two hundred forty-seven participants were recruited. Height, weight and WC were measured. Ten thousand, six hundred fifty-nine participants with complete data were included. Adiposity categories were defined as: BMI(N)/WC(N), BMI(N)/WC(O), BMI(O)/WC(N), and BMI(O)/WC(O) (N = non-obese and O = obese). Population attributable fraction, area under the receiver operating characteristic curve (AUC), and odds ratios (OR) were calculated. RESULTS: Participants were on average 48 years old and 50 % were men. The proportions of BMI(N)/WC(N), BMI(N)/WC(O), BMI(O)/WC(N) and BMI(O)/WC(O) were 68, 12, 2 and 18 %, respectively. A lower proportion of diabetes was attributable to obesity defined using BMI alone compared to BMI and WC combined (32 % vs 47 %). AUC for diabetes was also lower when obesity was defined using BMI alone (0.62 vs 0.66). Similar results were observed for all outcomes. The odds for hypertension, dyslipidaemia, diabetes and CVD were increased for those with BMI(N)/WC(O) (OR range 1.8-2.7) and BMI(O)/WC(O) (OR 1.9-4.9) compared to those with BMI(N)/WC(N). CONCLUSIONS: Current population monitoring, assessing obesity by BMI only, misses a proportion of the population who are at increased health risk through excess adiposity. Improved identification of those at increased health risk needs to be considered for better prioritisation of policy and resources

Dietary factors and Type 2 diabetes in the Middle East : what is the evidence for an association? - A systematic review.

This review aims to search and summarise the available evidence on the association between dietary factors and type 2 diabetes mellitus (T2DM) in Middle Eastern populations, where diabetes prevalence is among the highest in the world. Electronic databases were searched; authors, libraries, and research centres in the Middle East were contacted for further studies and unpublished literature. Included studies assessed potential dietary factors for T2DM in Middle Eastern adults. Two reviewers assessed studies independently. Extensive searching yielded 17 studies which met the inclusion criteria for this review. The findings showed that whole-grain intake reduces the risk of T2DM, and potato consumption was positively correlated with T2DM. Vegetables and vegetable oil may play a protective role against T2DM. Dietary patterns that are associated with diabetes were identified, such as Fast Food and Refined Grains patterns. Two studies demonstrated that lifestyle interventions decreased the risk of T2DM. In summary, the identified studies support an association between some dietary factors and T2DM; however, many of the included studies were of poor methodological quality so the findings should be interpreted with caution. The review draws attention to major gaps in current evidence and the need for well-designed studies in this area

Protective effect of Dendrobium officinale polysaccharides on experimental Sjogren's syndrome

Sjogren's syndrome (SS), usually described as a chronic inflammation which results in xerostomia (dry mouth) and xerophthalmia (dry eyes). According to the theory of traditional Chinese medicine, body fluid impairment causes the dryness, inducing water secretion deficiency. Discovery of a family of water-specific membrane channel proteins, the aquaporins, provides an interesting molecular mechanism of water permeability and transportation which were found abnormal in tissues of SS patients. Thus, this dryness may lead to the dysfunction in organs as various systematic manifestations. We established an autoallergic mouse model in vivo, and human salivary gland cell line A-253 in vitro. Polysaccharides of Dendrobium officinale (DP) were administrated as treatment, which was described to nourish yin and promote the body fluid. Results showed that immunization with SG autoantigen induced decrease of body weight and increased water intake, decreased AQP5 expression in a series of organs related to body fluid. Sera from model mice induced apoptosis of A-253 cells with activation of caspase-3. Administration of DP could reverse these pathological changes in both the animal and cell model. Thus, DP may be a promising candidate for the treatment of SS by up-regulating the expression of AQP-5 and protecting cells from apoptosis. © 2010 The Berkeley Electronic Press. All rights reserved.published_or_final_versio