Comparing demand functions when different price manipulations are used: Does unit price help?

Six hens pecked a key (Experiment 1) or pushed a door (Experiment 2) to obtain food reinforcement. In both experiments and as an analogue of price changes, the response requirements were varied in two ways: by increasing the number of responses required and by increasing the required force of each response. The two price manipulations (response number and response force) had different effects on behavior and produced different-shaped demand functions when the rates of consumption were plotted logarithmically against the price analogues. Irrespective of response topography, when the number of required responses was varied, the data paths appeared linear, with slopes close to -1.0. When the required force of each keypeck and doorpush was varied, the data paths were clearly curved, with increasingly steep downward slopes as the force increased. Using the concept of unit price did not fully remove the different effects of the two price manipulations. Those differences are best attributed to the differing times needed in order to complete each response unit under those price manipulations

Security Protocol Analysis and Blockchains

This work serves to explore the use of protocol verification tools, in this case AVISPA and SPAN, to verify a protocol used to establish blockchain identities as well as a protocol used for electronic voting that runs on top of a blockchain, leveraging blockchain as a platform. We explore the protocol verification tools themselves, as well as the modeling languages, CAS+ and HLPSL, used to write protocol specifications for verification by these tools. We determine that it is possible to verify a protocol regarding establishment of blockchain identities as well as that it is not possible to verify protocols which leverage blockchain as a platform, at least with the toolchain used and the CAS+ encoding of the protocol

Reinforcer magnitude and demand under fixed-ratio schedules with domestic hens

This study compared three methods of normalizing demand functions to allow comparison of demand for different commodities and examined how varying reinforcer magnitudes affected these analyses. Hens responded under fixed-ratio schedules in 40-min sessions with response requirement doubling each session and with 2-s, 8-s, and 12-s access to wheat. Over the smaller fixed ratios overall response rates generally increased and were higher the shorter the magazine duration. The logarithms of the number of reinforcers obtained (consumption) and the fixed ratio (price) were well fitted by curvilinear demand functions (Hursh et al., 1988. Journal of the Experimental Analysis of Behavior 50, 419–440) that were inelastic (b negative) over small fixed-ratios. The fixed ratio with maximal response rate (Pmax) increased, and the rate of change of elasticity (a) and initial consumption (L) decreased with increased magazine duration. Normalizing consumption using measures of preference for various magazine durations (3-s vs. 3-s, 2-s vs. 8-s, and 2-s vs. 12-s), obtained using concurrent schedules, gave useful results as it removed the differences in L. Normalizing consumption and price (Hursh and Winger, 1995. Journal of the Experimental Analysis of Behavior 64, 373–384) unified the data functions as intended by that analysis. The exponential function (Hursh and Silberberg, 2008. Psychological Review, 115, 186–198) gave an essential value that increased (i.e., α decreased significantly) as magazine duration decreased. This was not as predicted, since α should be constant over variations in magazine duration, but is similar to previous findings using a similar procedure with different food qualities (hens) and food quantities (rats)

Water: a neglected nutrient in the young child? A South African perspective

Water is considered an essential nutrient because the body cannot produce enough water itself, by metabolism of food, to fulfil its need.When the quantity or quality of water is inadequate, health problems result, most notably dehydration and diarrhoea. As a result of contaminated water and poor hygiene, related infections are still a serious problem. Indeed, in the South African setting water availability and sanitation are critical issues because of the prevalence of childhood diarrhoea and also the HIV/AIDS crisis.Though considerable efforts have been made to improve the water and sanitation problems in South Africa – especially with regard to water supply infrastructure – there is still room for much improvement.Water is a healthy alternative to calorie-dense, non-nutritive beverages, such as artificial fruit drinks and soda. The latter should be avoided as they contribute little other than energy and may contribute to overweight and obesity.Also, they displace more nutritious foods from the child’s diet. Consumption of fruit juice should also be limited. These issues highlight the need for a specific guideline relating to water intake in the paediatric food-based dietary guidelines

A colorimetric method for the determination of deoxyribonucleic acid in adipose tissue.

A method is described for measuring the deoxyribonucleic acid (DNA) content of small samples of adipose tissue or free fat cells. Lipids and acid-soluble nucleotides are first removed by extraction with a cold diethyl ether - ethanol mixture containing 10 per cent. ml V of trichloroacetic acid. DNA is then measured by hydrolysing the nucleoprotein residue in a 5 per cent. solution of trichloroacetic acid at 90 QC for 20 min, followed by treatment with p-nitrophenylhydrazine and measurement of the hydrazone at 560 nm. Several aspects of the method have been critically examined in order to determine the optimum conditions. The method is satisfactorily reproducible

Is the Rise in Reported Dementia Mortality Real? Analysis of Multiple-Cause-of-Death Data for Australia and the United States

Official statistics in Australia and the United States show large recent increases in dementia mortality rates. In this study, we assessed whether these trends are biased by an increasing tendency of medical certifiers (predominantly physicians) to report on the death certificate that dementia was a direct cause of death. Regression models of multiple-cause-of-death data in Australia (2006-2016) and the United States (2006-2017) were constructed to adjust dementia mortality rates for changes in death certification practices. Compared with official statistics, the recent increase in adjusted age-standardized dementia death rates was less than half as large in Australia and about two-thirds as large in the United States. Further adjustment for changes in reporting of dementia anywhere on the death certificate implied even lower increases in dementia mortality. Declines in reporting of cardiovascular diseases as comorbid conditions also contributed to rises in dementia mortality rates. The increasing likelihood of dementia's being reported as directly leading to death largely explains recent increases in dementia mortality rates in both countries. However, studies have found that reported dementia on death certificates remains low compared with clinical evaluations of its prevalence. Improved guidance and training for certifiers in reporting of dementia on death certificates will help standardize mortality statistics within and between countries

Raman signatures of classical and quantum phases in coupled dots: A theoretical prediction

We study electron molecules in realistic vertically coupled quantum dots in a strong magnetic field. Computing the energy spectrum, pair correlation functions, and dynamical form factor as a function of inter-dot coupling via diagonalization of the many-body Hamiltonian, we identify structural transitions between different phases, some of which do not have a classical counterpart. The calculated Raman cross section shows how such phases can be experimentally singled out.Comment: 9 pages, 2 postscript figures, 1 colour postscript figure, Latex 2e, Europhysics Letters style and epsfig macros. Submitted to Europhysics Letter

Naval History by Conspiracy Theory: The British Admiralty before the First World War and the Methodology of Revisionism

Revisionist interpretations of British naval policy in the Fisher era claim that an elaborate smoke screen was created to hide the Royal Navy’s real policies; while documents showing the true goals were systematically destroyed. By asserting this, revisionists are able to dismiss those parts of the documentary record that contradict their theories, while simultaneously excusing the lack of evidence for their theories by claiming it has been destroyed. This article shows that this methodology is misleading and untenable