Spectral properties of the renormalization group at infinite temperature

The renormalization group (RG) approach is largely responsible for the considerable success that has been achieved in developing a quantitative theory of phase transitions. Physical properties emerge from spectral properties of the linearization of the RG map at a fixed point. This article considers RG for classical Ising-type lattice systems. The linearization acts on an infinite-dimensional Banach space of interactions. At a trivial fixed point (zero interaction), the spectral properties of the RG linearization can be worked out explicitly, without any approximation. The results are for the RG maps corresponding to decimation and majority rule. They indicate spectrum of an unusual kind: dense point spectrum for which the adjoint operators have no point spectrum at all, only residual spectrum. This may serve as a lesson in what one might expect in more general situations.Comment: 12 page

Studying biological science does not lead to adoption of a healthy lifestyle

Aims: The lifestyle and physical activity (PA) habits of young people play a key role in the prevention of cardiovascular and metabolic diseases at older ages. The current generation of biological science students at university holds promise for better future medicine and medical technology. However, their physical fitness and lifestyle are often ignored. Methods: Lifestyle, PAs and common risk factors for cardiovascular disease before, and at, university were collected from 408 students using self-completed, anonymous surveys between the academic years of 2017 and 2019 from the School of Biological Sciences, University of Reading. Statistical analysis was performed using SAS® 9.4 software. Results: Among the 408 participants, 134 were male and 274 were female with a mean (SD) age of 19.6 (2.24). Approximately 19% of participants consumed alcohol beyond the safe limit of <14 units/week (112 g/week). Among them, 65% were males. Before university, 47% of students failed to meet the UK National Physical Activity Guidelines (NPAG) which increased to 56% during university with males exhibiting a steeper incline. Compared to their lifestyles before university, more students had insufficient sleep and displayed greater sedentariness during university. Moreover, 16% of students declared no engagement in PA which was greater than the value of 12% before university. Fitness perceptions worsened by 11% during university particularly for females. Statistical analysis revealed that gender, BMI and fitness perceptions were significantly correlated with PA levels. The most prevalent explanation for inadequacy in meeting NPAG was insufficient time. Conclusion: Compared to their pre-university lifestyles, biological science students at university are more likely to adopt unhealthier behaviours with less time for exercise and prolonged sedentary behaviours, which increases the risk for cardiovascular diseases. It is important to raise awareness of their fitness perceptions and to encourage health-promoting programmes at university

Simple one-dimensional quantum-mechanical model for a particle attached to a surface

We present a simple one-dimensional quantum-mechanical model for a particle attached to a surface. We solve the Schr\"odinger equation in terms of Weber functions and discuss the behavior of the eigenvalues and eigenfunctions. We derive the virial theorem and other exact relationships as well as the asymptotic behaviour of the eigenvalues. We calculate the zero-point energy for model parameters corresponding to H adsorbed on Pd(100) and also outline the application of the Rayleigh-Ritz variational method

The spatially resolved Kennicutt-Schmidt relation in the HI dominated regions of spiral and dwarf irregular galaxies

We study the Kennicutt-Schmidt relation between average star formation rate and average cold gas surface density in the Hi dominated ISM of nearby spiral and dwarf irregular galaxies. We divide the galaxies into grid cells varying from sub-kpc to tens of kpc in size. Grid-cell measurements of low SFRs using H-alpha emission can be biased and scatter may be introduced because of non-uniform sampling of the IMF or because of stochastically varying star formation. In order to alleviate these issues, we use far-ultraviolet emission to trace SFR, and we sum up the fluxes from different bins with the same gas surface density to calculate the average $\Sigma_{SFR}$ at a given value of $\Sigma_{gas}$. We study the resulting Kennicutt-Schmidt relation in 400 pc, 1 kpc and 10 kpc scale grids in nearby massive spirals and in 400 pc scale grids in nearby faint dwarf irregulars. We find a relation with a power law slope of 1.5 in the HI-dominated regions for both kinds of galaxies. The relation is offset towards longer gas consumption timescales compared to the molecular hydrogen dominated centres of spirals, but the offset is an order-of-magnitude less than that quoted by earlier studies. Our results lead to the surprising conclusion that conversion of gas to stars is independent of metallicity in the HI dominated regions of star-forming galaxies. Our observed relations are better fit by a model of star formation based on thermal and hydrostatic equilibrium in the ISM, in which feedback driven turbulence sets the thermal pressure.Comment: 11 pages, 7 figures, 5 tables. Accepted for publication in MNRAS Main Journal. For the definitive version visit http://mnras.oxfordjournals.org

Simulating Z_2 topological insulators with cold atoms in a one-dimensional optical lattice

We propose an experimental scheme to simulate and detect the properties of time-reversal invariant topological insulators, using cold atoms trapped in one-dimensional bichromatic optical lattices. This system is described by a one-dimensional Aubry-Andre model with an additional SU(2) gauge structure, which captures the essential properties of a two-dimensional Z2 topological insulator. We demonstrate that topologically protected edge states, with opposite spin orientations, can be pumped across the lattice by sweeping a laser phase adiabatically. This process constitutes an elegant way to transfer topologically protected quantum states in a highly controllable environment. We discuss how density measurements could provide clear signatures of the topological phases emanating from our one-dimensional system.Comment: 5 pages +, 3 figures, to appear in Physical Review

Tradisi Pemakaman Rambu Solo Di Tana Toraja Dalam Novel Puya Ke Puya Karya Faisal Oddang (Kajian Interpretatif Simbolik Clifford Geertz)

Penelitian ini mengkaji tentang tradisi Rambu Solo yang ada di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang dengan teori Clifford Geertz yang terdiri atas sistem pengetahuan, sistem nilai, dan sistem simbol. Tujuan penelitian ini adalah 1) mendeskripsikan sistem pengetahuan pada tradisi Rambu Solo di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang; 2) mendeskripsikan sistem nilai pada tradisi Rambu Solo di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang; 3) mendeskripsikan sistem simbol pada tradisi Rambu Solo di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang. Pendekatan yang digunakan dalam penelitian ini adalah pendekatan antropologi sastra, yaitu pendekatan yang digunakan untuk meneliti sistem budaya atau adat dari suatu kebudayaan tertentu dalam masyarakat. Penelitian ini mengkhususkan pada tradisi yang tumbuh dalam masyarakat yang ada dalam novel Puya ke Puya karya Faisal Oddang, yaitu Tana Toraja. Teknik pengumpulan data yang digunakan dalam penelitian ini adalah baca catat. Teknik analisis data yang digunakan adalah hermeneutika. Hasil penelitian ini adalah sistem pengetahuan yang terdapat pada tradisi Rambu Solo di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang terdiri atas dua bentuk, yaitu 1) pemakaman Rambu Solo dan 2) pemakaman bayi di pohon tarra. Sistem pengetahuan tersebut menginterpretasikan perilaku masyarakat yang sudah ada. Sistem nilai yang terdapat pada tradisi Rambu Solo di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang terdiri atas empat hal, yaitu 1) nilai religi, 2) nilai kekeluargaan, 3) nilai prestise, dan 4) nilai kebersamaan.&nbsp; Sistem Simbol yang terdapat pada tradisi Rambu Solo di Tana Toraja dalam novel Puya ke Puya karya Faisal Oddang terdiri atas enam hal, yaitu 1) simbol ritual, 2) simbol perlengkapan ritual, 3) simbol nyanyian, 4) simbol bangsawan, 5) simbol arwah, 6) simbol melayat . Macam-macam simbol yang dijelaskan tersebut mempunyai makna dan berhubungan dengan tradisi Rambu Solo di Toraja. Kata kunci : tradisi, ritual, adat, dan interpretatif simboli

Acceleration and vacuum temperature

The quantum fluctuations of an "accelerated" vacuum state, that is vacuum fluctuations in the presence of a constant electromagnetic field, can be described by the temperature \TEH. Considering \TEH for the gyromagnetic factor $g=1$ we show that \TEH(g=1)=\THU, where \THU is the Unruh temperature experienced by an accelerated observer. We conjecture that both particle production and nonlinear field effects inherent in the Unruh accelerated observer case are described by the case $g=1$ QED of strong fields. We present rates of particle production for $g=0,1,2$ and show that the case $g=1$ is experimentally distinguishable from $g=0,2$. Therefore, either accelerated observers are distinguishable from accelerated vacuum or there is unexpected modification of the theoretical framework.Comment: 4 pages, 1 figure; expanded discussion of experimental observables, added references, version appearing in Phys Rev