Variations on the Vev Flip-Flop: Instantaneous Freeze-out and Decaying Dark Matter

In this work we consider a simple model for dark matter and identify regions of parameter space where the relic abundance is set via kinematic thresholds, which open and close due to thermal effects. We discuss instantaneous freeze-out, where dark matter suddenly freezes-out when the channel connecting dark matter to the thermal bath closes, and decaying dark matter, where dark matter freezes-out while relativistic and later decays when a kinematic threshold temporarily opens. These mechanisms can occur in the vicinity of a one-step or a two-step phase transition. In all cases thermal effects provide this dynamic behaviour, while ensuring that dark matter remains stable until the present day.Comment: 23 pages, 13 figures; v2: version matched to journal (JHEP), added a detailed discussion of further two-to-two processe

3D model of amphioxus steroid receptor complexed with estradiol

The origins of signaling by vertebrate steroids are not fully understood. An important advance was the report that an estrogen-binding steroid receptor [SR] is present in amphioxus, a basal chordate with a similar body plan as vertebrates. To investigate the evolution of estrogen binding to steroid receptors, we constructed a 3D model of amphioxus SR complexed with estradiol. This 3D model indicates that although the SR is activated by estradiol, some interactions between estradiol and human ER[alpha] are not conserved in the SR, which can explain the low affinity of estradiol for the SR. These differences between the SR and ER[alpha] in the steroid-binding domain are sufficient to suggest that another steroid is the physiological regulator of the SR. The 3D model predicts that mutation of Glu-346 to Gln will increase the affinity of testosterone for amphioxus SR and elucidate the evolution of steroid binding to nuclear receptors

A Grounded Exploration of Sales and Distribution Channel Structures in Thirteen Industries in India Leading to a Classification Scheme

Innovation is a fundamental virtue of marketing. In this paper, a case is made to promote the use of innovative and novel combinations of research methodologies to derive new insights of business phenomena. This study is an attempt to understand and explain the sales and distribution channel structures in thirteen different industries in India. The investigation adopted a mix of case research and grounded theoretic research methodologies in exploring the subject under scrutiny. The study offers a classification scheme for grouping marketing channels into homogenous clusters based on similarity/dissimilarity using multivariate multidimensional mapping techniques. This scheme offers to explain the variety found in structures and suggests alternative channel possibilities. Such a scheme can be used in formulating marketing strategies and in deciding upon operational issues as well. While the main setting of the reported findings is Indian, the findings may prove to be useful beyond the national setting. Usual disclaimers associated with qualitative research methodology (Gummesson 1988) apply in this case concerning the generalisability and validity of the findings. This paper’s contribution is not as much in offering a schema as it is in suggesting an analytical plan/process that helps in visualising structures and associated strategies de novo.

Financial Coaching: A New Approach for Asset Building?

Through a literature review and interviews with nonprofit financial coaches, examines the concepts, training, and capacity building involved in financial coaching for low-income families, as well as critiques of existing models and their implications

Galois extensions of Lubin-Tate spectra

Let E_n be the n-th Lubin-Tate spectrum at a prime p. There is a commutative S-algebra E^{nr}_n whose coefficients are built from the coefficients of E_n and contain all roots of unity whose order is not divisible by p. For odd primes p we show that E^{nr}_n does not have any non-trivial connected finite Galois extensions and is thus separably closed in the sense of Rognes. At the prime 2 we prove that there are no non-trivial connected Galois extensions of E^{nr}_n with Galois group a finite group G with cyclic quotient. Our results carry over to the K(n)-local context.Comment: revised version in final for

Assessing housing quality and its impact on health, safety and sustainability

Background The adverse health and environmental effects of poor housing quality are well established. A central requirement for evidence-based policies and programmes to improve housing standards is a valid, reliable and practical way of measuring housing quality that is supported by policy agencies, the housing sector, researchers and the public. Methods This paper provides guidance on the development of housing quality-assessment tools that link practical measures of housing conditions to their effects on health, safety and sustainability, with particular reference to tools developed in New Zealand and England. Results The authors describe how information on housing quality can support individuals, agencies and the private sector to make worthwhile improvements to the health, safety and sustainability of housing. The information gathered and the resultant tools developed should be guided by the multiple purposes and end users of this information. Other important issues outlined include deciding on the scope, detailed content, practical administration issues and how the information will be analysed and summarised for its intended end users. There are likely to be considerable benefits from increased international collaboration and standardisation of approaches to measuring housing hazards. At the same time, these assessment approaches need to consider local factors such as climate, geography, culture, predominating building practices, important housing-related health issues and existing building codes. Conclusions An effective housing quality-assessment tool has a central role in supporting improvements to housing. The issues discussed in this paper are designed to motivate and assist the development of such tools

Dynamic Freeze-In: Impact of Thermal Masses and Cosmological Phase Transitions on Dark Matter Production

The cosmological abundance of dark matter can be significantly influenced by the temperature dependence of particle masses and vacuum expectation values. We illustrate this point in three simple freeze-in models. The first one, which we call kinematically induced freeze-in, is based on the observation that the effective mass of a scalar temporarily becomes very small as the scalar potential undergoes a second order phase transition. This opens dark matter production channels that are otherwise forbidden. The second model we consider, dubbed vev-induced freeze-in, is a fermionic Higgs portal scenario. Its scalar sector is augmented compared to the Standard Model by an additional scalar singlet, $S$, which couples to dark matter and temporarily acquires a vacuum expectation value (a two-step phase transition or `vev flip-flop'). While $\langle S \rangle \neq 0$, the modified coupling structure in the scalar sector implies that dark matter production is significantly enhanced compared to the $\langle S \rangle = 0$ phases realised at very early times and again today. The third model, which we call mixing-induced freeze-in, is similar in spirit, but here it is the mixing of dark sector fermions, induced by non-zero $\langle S \rangle$, that temporarily boosts the dark matter production rate. For all three scenarios, we carefully dissect the evolution of the dark sector in the early Universe. We compute the DM relic abundance as a function of the model parameters, emphasising the importance of thermal corrections and the proper treatment of phase transitions in the calculation.Comment: 26 pages, 11 figures, v2: matches journal version, change to the value of a benchmark coupling in section II, impact of thermal masses increase

Negotiated Tutoring: An Approach to Interaction in Intelligent Tutoring Systems

This thesis describes a general approach to tutorial interaction in Intelligent Tutoring Systems, called "Negotiated Tutoring". Some aspects of the approach have been implemented as a computer program in the 'KANT' (Kritical Argument Negotiated Tutoring) system. Negotiated Tutoring synthesises some recent trends in Intelligent Tutoring Systems research, including interaction symmetry, use of explicit negotiation in dialogue, multiple interaction styles, and an emphasis on cognitive and metacognitive skill acquisition in domains characterised by justified belief. This combination of features has not been previously incorporated into models for intelligent tutoring dialogues. Our approach depends on modelling the high-level decision-making processes and memory representations used by a participant in dialogue. Dialogue generation is controlled by reasoning mechanisms which operate on a 'dialogue state', consisting of conversants' beliefs, a set of possible dialogue moves, and a restricted representation of the recent utterances generated by both conversants. The representation for conversants' beliefs is based on Anderson's (1983) model for semantic memory, and includes a model for dialogue focus based on spreading activation. Decisions in dialogue are based on preconditions with respect to the dialogue state, higher level educational preferences which choose between relevant alternative dialogue moves, and negotiation mechanisms designed to ensure cooperativity. The domain model for KANT was based on a cognitive model for perception of musical structures in tonal melodies, which extends the theory of Lerdahl and Jackendoff (1983). Our model ('GRAF' - GRouping Analysis with Frames) addresses a number of problems with Lerdahl and Jackendoff's theory, notably in describing how a number of unconscious processes in music cognition interact, including elements of top-down and bottom-up processing. GRAF includes a parser for musical chord functions, a mechanism for performing musical reductions, low-level feature detectors and a frame-system (Minsky 1977) for musical phrase structures

Optimization of conditions for vitrification of aqueous solutions of relevance to cryobiology

Cryopreservation is a technology with wide ranging applications including helping to prevent specis extinction (Hopkins and Herr, 2010). However, the current applicability of cryopreservation protocols is limited. This limitation warranted experimentation that could contribute to the optimization of current protocols for cryopreservation. The experiments presented herein were designed to contribute to the plunge-cooling method of cryopreservation. The importance for further development of current plunge-cooling methods is for the cryopreservation of cell-types sensitive to the other method of cryopreservation, slow-equilibrium freezing. The purpose for plunge-cooling is to cool a sample from ambient temperature to liquid nitrogen temperature at a fast rate. If cooling is sufficiently fast, ice-formation is inhibited. This creates a glass-like vitrified state. To optimize the probability of vitrification, current approaches were modified. Different cooling methods were investigated. Containers called cryostraws were crafted from six different materials, materials with different thermal conductivity properties; all straws were of similar size. The minimum concentrations of several ice-inhibitors (cryoprotectants) needed to achieve vitrification were studied. Novel cooling methods, which involved the use of spinning coolant and/or semi-solid nitrogen, called slush nitrogen (SN), as the cooling medium were invented and then tested. The novel methods enabled rates of cooling that were far faster than previously possible. A chronic problem that plagued the progress with plunge cooling was the difficulty in making SN repeatable. The cause of this problem was researched and identified as contamination of the LN by condensed oxygen. The quantified cooling rates of similar sized containers constructed from different materials yielded unexpected results. We determined that a material\u27s thermal conductivity was a poor predictor of cooling rates. In fact, implementing a material that was porous to LN, such as polyvinyl chloride, yielded the fastest rate of cooling, indicating that a material\u27s porosity is a much better predictor of cooling rate. --Document