DIGITAL ENCODING OF TELEVISION SIGNALS USING THE PULSE WIDTH MODULATOR

An attempt is made to quantify the circuit complexity and mean circuit speed of linearly quantized straight PCM video encoding techniques. Any significant reduction in circuit complexity (i.e. the number of active and passive devices to be integrated) is considered important since this determines: chip area and yield if the encoder is to be fully integrated. Analysis indicates that the complexity of the more highly developed straight PCM video encoders can be reduced by typically a factor 3 using either non-programmed sequential encoding, pulse width modulator encoding or programmed sequential encoding (closed loop successive approximation). The encoder studied in this work is an 8-bit pulse width modulator video encoder using a 2-step production line technique and a detailed design procedure for a prototype encoder is given. This encoder is considered to achieve 7-bit resolution at a sampling rate of 13.3MHZ. A mathematical model of the encoder-decoder system is developed for numerical evaluation of the effect of encoder errors and white Gaussian noise upon a coded and decoded video signal. A triangular wave test is applied to examine the effect of encoder errors upon the statio transfer characteristic of the encoder. Dynamic errors are investigated by simulating colour subcarrier at the model input and observing the phase and gain errors at the filtered codec output. Using differential phase and gain, an attempt is made to determine a circuit design and alignment criterion such that most practical codecs will fall within specific bounds on these parameters (taken as ±6° and ±6% respective1y). In the absense of dither, Monte Carlo analysis indicates that the maximum voltage error incurred by each encoder error source should have a high probability (95%) of being less than a half quantum if 85 - 90% of codecs measured are to fall within the above bounds. If white Gaussian noise is used as a simple dither signal then the probability of a codec falling within the above bounds may increase to about 95%. Improvements to the encoder are discussed, including several automatic error correction techniques which combat instrumental errors and give a more robust PWM encoder. Also, by predetermining the most significant bit for each set of 4 coded bits it is possible to halve the encoder clock frequency (to 133MHZ) without significantly changing the encoder complexity

Extragalactic infrared spectroscopy

The spectra of galaxies in the near infrared atmospheric transmission windows are explored. Emission lines were detected due to molecular hydrogen, atomic hydrogen recombination lines, a line attributed to FEII, and a broad CO absorption feature. Lines due to H2 and FEII are especially strong in interacting and merging galaxies, but they were also detected in Seyferts and normal spirals. These lines appear to be shock excited. Multi-aperture measurements show that they emanate from regions as large as 15 kpc. It is argued that starbursts provide the most plausible and consistent model for the excitation of these lines, but the changes of relative line intensity of various species with aperture suggest that other excitation mechanisms are also operating in the outer regions of these galaxies

Covalent chemical modification of self- assembled fluorocarbon monolayers by low- energy CH<SUB>2</SUB>Br<SUB>2</SUB><SUP>+&#183;</SUP> ions: a combined ion/surface scattering and X-ray photoelectron spectroscopic investigation

Specific covalent chemical modification at the outermost atomic layers of fluorinated self-assembled monolayers (F-SAMs) on gold is achieved by bombardment with low-energy polyatomic ions (&lt;100 eV). The projectile ion CH2Br2+&#183; (m/z 172), mass and energy selected using a hybrid ion/surface scattering mass spectrometer and scattered from the F-SAM surface, CF3(CF2)7(CH2)2-S-Au, undergoes ion/surface reactions evident from the nature of the scattered ions, CH2F+ (m/z 33), CHBrF+ (m/z 111), and CF2Br+ (m/z 129). The chemical transformation of the reactive F-SAM surface was independently monitored by in situ chemical sputtering with the projectile Xe+&#183;. Representative species sputtered from the modified surface include CF2Br+, an indicator of terminal CF3 to CF2Br conversion. X-ray photoelectron spectroscopy (XPS) was used to confirm the presence of organic bromine at the surface; Br (3P3/2) and Br (3P&#189;) peaks were present at binding energies of 182 and 190 eV, respectively. XPS analysis also revealed increased surface modification at higher collision energies in these reactive ion bombardment experiments, as exemplified by the increased hydrocarbon/fluorocarbon peak ratio in the C(1s) region and incorporation of oxygen in the surface seen in the observation of an O(1s) peak

Quantum fluctuations on a thick de Sitter brane

We investigate quantum fluctuations on a de Sitter (dS) brane, which has its own thickness, in order to examine whether or not the finite thickness of the brane can act as a natural cut-off for the Kaluza-Klein (KK) spectrum. We calculate the amplitude of the KK modes and the bound state by using the zeta function method after a dimensional reduction.We show that the KK amplitude is finite for a given brane thickness and in the thin wall limit the standard surface divergent behavior is recovered. The strength of the divergence in the thin wall limit depends on the number of dimensions, e.g., logarithmic on a two dimensional brane and quadratic on a four dimensional brane. We also find that the amplitude of the bound state mode and KK modes depends on the choice of renormalization scale; and for fixed renormalization scales the bound state mode is insensitive to the brane thickness both for two and four-dimensional dS branes.Comment: 23 pages, typos correcte

Identification of post-traumatic stress disorder following ICU

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Ability of verbal autopsy data to detect deaths due to uncontrolled hyperglycaemia:testing existing methods and development and validation of a novel weighted score

Objectives: Verbal autopsy (VA) is a useful tool to ascertain cause of death where no other mechanisms exist. We aimed to assess the utility of VA data to ascertain deaths due to uncontrolled hyperglycaemia and to develop a weighted score (WS) to specifically identify cases. Cases were identified by a study or site physician with training in diabetes. These diagnoses were also compared with diagnoses produced by a standard computer algorithm (InterVA-4). Setting: This study was done using VA data from the Health and Demographic Survey sites in Agincourt in rural South Africa. Validation of the WS was done using VA data from Karonga in Malawi. Participants: All deaths from ages 1 to 49 years between 1992 and 2015 and between 2002 and 2016 from Agincourt and Karonga, respectively. There were 8699 relevant deaths in Agincourt and 1663 in Karonga. Results: Of the Agincourt deaths, there were 77 study physician classified cases and 58 computer algorithm classified cases. Agreement between study physician classified cases and computer algorithm classified cases was poor (Cohen’s kappa 0.14). Our WS produced a receiver operator curve with area under the curve of 0.952 (95% CI 0.920 to 0.985). However, positive predictive value (PPV) was below 50% when the WS was applied to the development set and the score was dominated by the necessity for a premortem diagnosis of diabetes. Independent validation showed the WS performed reasonably against site physician classified cases with sensitivity of 86%, specificity of 99%, PPV of 60% and negative predictive value of 99%. Conclusion: Our results suggest that widely used VA methodologies may be missing deaths due to uncontrolled hyperglycaemia. Our WS may offer improved ability to detect deaths due to uncontrolled hyperglycaemia in large populations studies where no other means exist

Demographic Patterns and Limitation of Grey Wolves, Canis lupus, in and Near Pukaskwa National Park, Ontario

In response to concern regarding the growth and long-term viability of the wolf population in and near Pukaskwa National Park, a study of demographic patterns and limitation of radio-collared wolves (Canis lupus) was completed between 1994 and 1998. The mean annual finite rate of increase (0.96) suggested that population growth of wolves was limited and declining slightly. Small pack sizes, high cumulative mortality, and low reproductive success also suggested a declining population. Two limiting factors, ungulate biomass and human-caused mortality, were examined to determine the importance of each in limiting the population growth of wolves. Ungulate biomass was involved because occurrence of natural-caused mortality was high (9 of 17 wolves) compared with other studies. In addition, consumption rates were low and similar to other studies where starvation and other signs of malnutrition were noted. Further, Moose densities in the study area were low to moderate and below thresholds indicating nutritional stress for wolves. Occurrence of human-caused mortality was high (8 of 17 wolves) suggesting that it was also an important limiting factor, particularly given the low availability of ungulate biomass and reproduction noted in this study. Based on present demographic patterns, ungulate biomass, and human-caused mortality, the wolf population likely will remain at present low densities or continue to decline

Randomly Amplified DNA Fingerprinting: A Culmination of DNA Marker Technologies Based on Arbitrarily-Primed PCR Amplification

Arbitrarily-primed DNA markers can be very useful for genetic fingerprinting and for facilitating positional cloning of genes. This class of technologies is particularly important for less studied species, for which genome sequence information is generally not known. The technologies include Randomly Amplified Polymorphic DNA (RAPD), DNA Amplification Fingerprinting (DAF), and Amplified Fragment Length Polymorphism (AFLP). We have modified the DAF protocol to produce a robust PCR-based DNA marker technology called Randomly Amplified DNA Fingerprinting (RAF). While the protocol most closely resembles DAF, it is much more robust and sensitive because amplicons are labelled with either radioactive (33)P or fluorescence in a 30-cycle PCR, and then separated and detected on large polyacrylamide sequencing gels. Highly reproducible RAF markers were readily amplified from either purified DNA or alkali-treated intact leaf tissue. RAF markers typically display dominant inheritance. However, a small but significant portion of the RAF markers exhibit codominant inheritance and represent microsatellite loci. RAF compares favorably with AFLP for efficiency and reliability on many plant genomes, including the very large and complex genomes of sugarcane and wheat. While the two technologies detect about the same number of markers per large polyacrylamide gel, advantages of RAF over AFLP include: (i) no requirement for enzymatic template preparation, (ii) one instead of two PCRs, and (iii) overall cost. RAF and AFLP were shown to differ in the selective basis of amplification of markers from genomes and could therefore be used in complementary fashion for some genetic studies

The pervasive nature of heterodox economic spaces at a time of neoliberal crisis: towards a “postneoliberal” anarchist future

Re-reading the economic landscape of the western world as a largely non-capitalist landscape composed of economic plurality, this paper demonstrates how economic relations in contemporary western society are often embedded in non-commodified practices such as mutual aid, reciprocity, co-operation and inclusion. By highlighting how the long-overlooked lived practices in the contemporary world of production, consumption and exchange are heavily grounded in the very types and essences of non-capitalist economic relations that have long been proposed by anarchistic visions of employment and organization, this paper displays that such visions are far from utopian: they are embedded firmly in the present. Through focusing on the pervasive nature of heterodox economic spaces in the UK in particular, some ideas about how to develop an anarchist future of work and organization will be proposed. The outcome is to begin to engage in the demonstrative construction of a future based on mutualism and autonomous modes of organization and representation. © 2012 The Authors. Antipode© 2012 Antipode Foundation Ltd.

Research needs for optimising wastewater-based epidemiology monitoring for public health protection

Wastewater-based epidemiology (WBE) is an unobtrusive method used to observe patterns in illicit drug use, poliovirus, and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). The pandemic and need for surveillance measures have led to the rapid acceleration of WBE research and development globally. With the infrastructure available to monitor SARS-CoV-2 from wastewater in 58 countries globally, there is potential to expand targets and applications for public health protection, such as other viral pathogens, antimicrobial resistance (AMR), pharmaceutical consumption, or exposure to chemical pollutants. Some applications have been explored in academic research but are not used to inform public health decision-making. We reflect on the current knowledge of WBE for these applications and identify barriers and opportunities for expanding beyond SARS-CoV-2. This paper critically reviews the applications of WBE for public health and identifies the important research gaps for WBE to be a useful tool in public health. It considers possible uses for pathogenic viruses, AMR, and chemicals. It summarises the current evidence on the following: (1) the presence of markers in stool and urine; (2) environmental factors influencing persistence of markers in wastewater; (3) methods for sample collection and storage; (4) prospective methods for detection and quantification; (5) reducing uncertainties; and (6) further considerations for public health use