Comment on `Glassy Transition in a Disordered Model for the RNA Secondary Structure'

In cond-mat/9907125 the low-temperature behavior of a model for RNA secondary structure was studied. It is claimed that the model exhibits a breaking of the replica symmetry, since the width of the distribution P(q) of overlaps may converge to a finite value at T=0. The authors used an exact enumeration method to obtain all ground states for a given RNA sequence. Because of the exponential growing degeneracy, only sequences up to length L=256 could be studied. Here it is shown that, in contrast to the previous results, by going to much larger sizes as L=2000 the variance coverges towards zero, i.e. P(q) is a delta-function in the thermodynamic limit.Comment: completely rewritten, comment to cond-mat/9907125 (PRL 84, 2026

Error threshold in simple landscapes

We consider the quasispecies description of a population evolving in both the "master sequence" landscape (where a single sequence is evolutionarily preferred over all others) and the REM landscape (where the fitness of different sequences is an independent, identically distributed, random variable). We show that, in both cases, the error threshold is analogous to a first order thermodynamical transition, where the overlap between the average genotype and the optimal one drops discontinuously to zero.Comment: 10 pages and 2 figures, Plain LaTe

Selling surveillance technology: semiotic themes in advertisements for ageing in place with dementia

Six advertisements were explored that sell surveillance technologies for people living with dementia through qualitative content analysis. Advertisements from the United Kingdom, Sweden, and the Netherlands were analysed to explore semiotic textual meaning and people living with dementia (N = 5) and carers (N = 4) responded to these advertisements. The semiotic themes report a “wanderer” discourse which signals to track people living with dementia, children pets and possessions. Mainly negative representations communicate the dangers of wandering towards younger-female carers, few positive representations show a smiling person with dementia and only one person was represented as interacting with technology. Participants did not understand the advertisements and people living with dementia felt stigmatised. There is a lack of reflexivity when people living with dementia are seen as objects. The reliance on stereotypes targeted at carers with misunderstood conceivable trackers hinders resilience for people living with dementia and implies the continuous stigmatisation that occurs when they are disregarded as human technology-users

What do we require from surveillance technology? A review of the needs of people with dementia and informal caregivers

Introduction: Dementia has become a major global concern and surveillance technology might provide support for informal caregivers and people with dementia. However, the needs of caregivers and people with dementia for surveillance technology have not been reviewed. Method: A scoping literature review was used to identify the needs of caregivers and/or people with dementia towards surveillance technology. Electronic database searching was undertaken on LexisNexis, PubMed, Scopus, EMBASE, MEDLINE, Cumulative Index to Nursing, Allied Health Literature, PsycINFO, Web of Science, Assistive Technology database, and Google Scholar. Eligible studies were synthesized by theme. Results: Twenty-eight eligible studies were identified, with the majority reporting the needs of caregivers rather than people with dementia. The predominant themes for caregivers were location accuracy, and increasing the safety of the person with dementia. People with dementia wanted simple useful technology that fits within their capacity and existing routines. Conclusions: The needs of people with dementia must be considered when designing surveillance products. Studies have mostly focused on caregivers and discount ST product requirements. Further work is required to establish effective use of surveillance technology in dementia care. Therefore, further research should cross analyze these results by examining both the needs of caregivers, and people with dementia

Probing the Higgs mechanism via γγ→W+W−\gamma\gamma\to W^+W^-

We investigate the sensitivity of the reaction $\gamma\gamma\to W^+W^-$ to the Higgs sector based on the complete one-loop corrections in the minimal Standard Model and the gauged non-linear $\sigma$-model. While this sensitivity is very strong for the suppressed cross-section of equally polarized photons and longitudinal W bosons, it is only marginal for the dominant mode of transverse polarizations. The corrections within the $\sigma$-model turn out to be UV-finite in accordance with the absence of \log\MH terms in the Standard Model with a heavy Higgs boson.Comment: 12 pages uuencoded postscrip

Gravitation Interaction and Electromagnetic Interaction in the Relativistic Universe with Total Zero and Local Non-Zero Energy

In the model of flat expansive homogeneous and isotropic relativistic universe with total zero and local non-zero energy the gravitation energy of bodies and the elecromagnetic energy of charged bodies can be localised.Comment: LaTeX, 10 pages, 1 figur

Bloch-Nordsieck Violation in Spontaneously Broken Abelian Theories

We point out that, in a spontaneously broken U(1) gauge theory, inclusive processes, whose primary particles are mass eigenstates that do not coincide with the gauge eigenstates, are not free of infrared logarithms. The charge mixing allowed by symmetry breaking and the ensuing Bloch-Nordsieck violation are here analyzed in a few relevant cases and in particular for processes initiated by longitudinal gauge bosons. Of particular interest is the example of weak hypercharge in the Standard Model where, in addition, left-right mixing effects arise in transversely polarized fermion beams.Comment: 4 pages, 1 figur

Possibility of the new type phase transition

The scalar field theory and the scalar electrodynamics quantized in the flat gap are considered. The dynamical effects arising due to the boundary presence with two types of boundary conditions (BC) satisfied by scalar fields are studied. It is shown that while the Neumann BC lead to the usual scalar field mass generation, the Dirichlet BC give rise to the dynamical mechanism of spontaneous symmetry breaking. Due to the later, there arises the possibility of the new type phase transition from the normal to spontaneously broken phase. The decreasing in the characteristic size of the quantization region (the gap size here) and increasing in the temperature compete with each other, tending to transport the system in the spontaneously broken and in the normal phase, respectively. The system evolves with a combined parameter, simultaneously reflecting the change in temperature and in the size. As a result, at the critical value of this parameter there occurs the phase transition from the normal phase to the spontaneously broken one. In particular, the usual massless scalar electrodynamics transforms to the Higgs model