Isomorphism in expanding families of indistinguishable groups

For every odd prime $p$ and every integer $n\geq 12$ there is a Heisenberg group of order $p^{5n/4+O(1)}$ that has $p^{n^2/24+O(n)}$ pairwise nonisomorphic quotients of order $p^{n}$. Yet, these quotients are virtually indistinguishable. They have isomorphic character tables, every conjugacy class of a non-central element has the same size, and every element has order at most $p$. They are also directly and centrally indecomposable and of the same indecomposability type. The recognized portions of their automorphism groups are isomorphic, represented isomorphically on their abelianizations, and of small index in their full automorphism groups. Nevertheless, there is a polynomial-time algorithm to test for isomorphisms between these groups.Comment: 28 page

Federal Credit Unions: Growth and Operations, 1934—1961

131 pagesThis study deals with federal credit unions on a national basis. It attempts to answer such questions as the following: what is a federal credit union? Where does the Federal Credit Union stand, as a financial institution, in our present day economy? Are there economies of scale in the larger credit unions’ operations? Should there be a tax upon the earnings of federal credit unions similar to the tax upon earnings of other financial institutions (such as commercial banks and savings and loan associations)? For what purpose do credit unions lend? This study also analyzes Federal Credit Union growth and operations. It attempts to point out the significant changes that have taken place in the Federal Credit Union since 1934. The method of presentation in this study is both historical and statistical. And the analysis of statistical data the emphasis is predominantly on developments in recent years

A CASE STUDY EVALUATING THE EFFECTS OF HIGH CYCLE THERMAL LOADING WITHIN A PRESSURISED WATER REACTOR MIXING TEE USING CONJUGATE CFD/FE METHODS

ABSTRACT In nuclear plant piping systems thermal fatigue damage can arise at locations where there is turbulent mixing of different temperature flows. The severity of this phenomenon is difficult to assess via plant instrumentation due to the high frequencies involved. NESC report EUR 22763 EN, published in 2007, defines the "Level 1" screening criterion for the design of austenitic stainless steel mixing tees, based on recorded incidents of fatigue cracking in civil power plants. The experimental data indicates that damage due to High Cycle Thermal Loading (HCTL) is unlikely to occur if the temperature difference between the hot and cold inlet streams is less than 80°C. The "Level 2" approach outlined by NESC provides a methodology for the calculation of a fatigue usage factor based on the assumption of a sinusoidal thermal loading at the most damaging frequency for a given ΔT. Advice is given on selection of heat transfer coefficient, fatigue curves, fatigue strength reduction factors and plasticity correction factors. Experience shows that these methods can be overly pessimistic when compared with plant operational experience. This paper describes a case study using the more detailed NESC "Level 3" evaluation of HCTL at a Pressurised Water Reactor (PWR) mixing tee using a coupled Computational Fluid Dynamics and Finite Element Analysis (CFD/FE) analysis to evaluate the complete load spectra together with the ASME 2010 fatigue S-N curve. The CFD model used is "conjugate", ie it calculates temperatures in both the fluid and the metal. Large Eddy Simulation (LES) was used to investigate HCTL effects using an appropriate mesh size to accurately predict the rapid fluctuations in metal temperature local to the surface. Metal temperature predictions using conjugate CFD analyses provided the input to finite element analysis, utilising rain-flow techniques, in order to derive fatigue usage factors in the areas of interest. This study found that the severity of HCTL is influenced by various factors such as flow conditions, local geometry including bore match features, integral conical reducers that allow progressive change in pipe radius as well as branch pipe swirl penetration

A global review of the ecosystem services provided by bivalve aquaculture:Services of bivalve aquaculture

Bivalve shellfish aquaculture provides many benefits to society, beyond their traditional market value. This study collates the evidence available on the provisioning, regulating and cultural ecosystem services provided by the bivalve species commonly used in aquaculture. For the first time, it synthesises this evidence to provide a global assessment of the potential market and non‐market economic value of bivalve aquaculture. Bivalves are filter feeders, filtering water and particulates, creating substrates which provide habitat to act as nursery grounds for other species. Goods from provisioning services include meat, worth an estimated $23.9 billion as well as, pearls, shell and poultry grit, with oyster shell being the most important, with a global potential worth of$5.2 billion. The most important regulating services are nutrient remediation. Cultivated bivalves remove 49,000 tonnes of nitrogen and 6,000 tonnes of phosphorus, worth a potential $1.20 billion. Currently, there is little evidence on the cultural services per year of bivalve aquaculture, but we argue that these cultural values are broad ranging, although difficult to quantify. Our assessment indicates that the global, non‐food bivalve aquaculture services are worth$6.47 billion ($2.95 billion–9.99 billion) per annum. However, this is likely to be an underestimate of the true value of bivalve aquaculture as there are significant gaps in evidence of the value for a number of key services. The analysis presented here can be used to indicate the likely scale of payments for ecosystem services provided by bivalve aquaculture, prior to more detailed assessments

Critical Review on the Public Health Impact of Norovirus Contamination in Shellfish and the Environment:A UK Perspective

We review the risk of norovirus (NoV) infection to the human population from consumption of contaminated shellfish. From a UK perspective, risk is apportioned for different vectors of NoV infection within the population. NoV spreads mainly by person-to-person contact or via unsanitary food handling. NoV also enters the coastal zone via wastewater discharges resulting in contamination of shellfish waters. Typically, NoV persists in the marine environment for several days, with its presence strongly linked to human population density, wastewater discharge rate, and efficacy of wastewater treatment. Shellfish bioaccumulate NoV and current post-harvest depuration is inefficient in its removal. While NoV can be inactivated by cooking (e.g. mussels), consumption of contaminated raw shellfish (e.g. oysters) represents a risk to human health. Consumption of contaminated food accounts for 3–11% of NoV cases in the UK (~74,000 cases/year), of which 16% are attributable to oyster consumption (11,800 cases/year). However, environmental and human factors influencing NoV infectivity remain poorly understood. Lack of standard methods for accurate quantification of infective and non-infective (damaged) NoV particles represent a major barrier, hampering identification of an appropriate lower NoV contamination limit for shellfish. Future management strategies may include shellfish quality assessment (at point of harvest or at point of supply) or harvesting controls. However, poor understanding of NoV inactivation in shellfish and the environment currently limits accurate apportionment and risk assessment for NoV and hence the identification of appropriate shellfish or environmental quality standards

Anarchy in the UK: Reading Beryl the Peril via historic conceptions of childhood

© 2014 Taylor & Francis. Much work within the field of childhood studies has focused on the social discourses through which childhood is understood. This article draws on this work in developing a critical framework for considering the appeal of Beryl the Peril. The article examines the influence of conceptualisations of childhood prevalent in the nineteenth and early twentieth centuries. These theorised children as disruptive and requiring restraint. Approved literature for children sought to socialise them into the adult order. However, a more subversive strain, identifiable in Lewis Carroll's Alice novels, celebrated an anarchic vision of childhood. This article examines how Beryl the Peril negotiated these conflicting conceptions of childhood. Beryl is an unruly force; her opponent, and representative of social authority, is Dad. Their clashes play out the tensions in these articulations of childhood. The development of Beryl over nearly 60 years provides an opportunity to examine how her subversive spirit has remained appealing

Further insights into the discoloration of TATB under ionizing radiation

To determine degradation products formed by exposure of TATB to ionizing radiation, a computational and experimental study is presented. Thermochemical and spectral data have been calculated using DFT at the MH06-HF/aug-cc-pVTZ level which suggest the formation of the cation radical derivative of TATB. Irradiated TATB samples showed the widely reported yellow-to-green discoloration, with measured CIE L*, a*, b* and RGB values correlating with total dose. Trace quantities of a mono-furazan derivative were detected by HPLC-MS; the discoloration is not attributed to this, but rather to the presence of a paramagnetic species (i.e., the cation), as detected by ESR measurements. Recrystallized irradiated TATB samples reverted to their original color, further suggesting it is the cation radical that is responsible for color change

Mechanical Structural Design of a MEMS-Based Piezoresistive Accelerometer for Head Injuries Monitoring: A Computational Analysis by Increments of the Sensor Mass Moment of Inertia.

This work focuses on the proof-mass mechanical structural design improvement of a tri-axial piezoresistive accelerometer specifically designed for head injuries monitoring where medium-G impacts are common; for example, in sports such as racing cars or American Football. The device requires the highest sensitivity achievable with a single proof-mass approach, and a very low error (<1%) as the accuracy for these types of applications is paramount. The optimization method differs from previous work as it is based on the progressive increment of the sensor proof-mass mass moment of inertia (MMI) in all three axes. Three different designs are presented in this study, where at each step of design evolution, the MMI of the sensor proof-mass gradually increases in all axes. The work numerically demonstrates that an increment of MMI determines an increment of device sensitivity with a simultaneous reduction of cross-axis sensitivity in the particular axis under study. This is due to the linkage between the external applied stress and the distribution of mass (of the proof-mass), and therefore of its mass moment of inertia. Progressively concentrating the mass on the axes where the piezoresistors are located (i.e., x- and y-axis) by increasing the MMI in the x- and y-axis, will undoubtedly increase the longitudinal stresses applied in that areas for a given external acceleration, therefore increasing the piezoresistors fractional resistance change and eventually positively affecting the sensor sensitivity. The final device shows a sensitivity increase of about 80% in the z-axis and a reduction of cross-axis sensitivity of 18% respect to state-of-art sensors available in the literature from a previous work of the authors. Sensor design, modelling, and optimization are presented, concluding the work with results, discussion, and conclusion