Many-body mobility edge due to symmetry-constrained dynamics and strong interactions

We provide numerical evidence combined with an analytical understanding of the many-body mobility edge for the strongly anisotropic spin-1/2 XXZ model in a random magnetic field. The system dynamics can be understood in terms of symmetry-constrained excitations about parent states with ferromagnetic and anti-ferromagnetic short range order. These two regimes yield vastly different dynamics producing an observable, tunable many-body mobility edge. We compute a set of diagnostic quantities that verify the presence of the mobility edge and discuss how weakly correlated disorder can tune the mobility edge further.Comment: 10 pages, 5 figure

SPIRAL Phase A: A Prototype Integral Field Spectrograph for the AAT

We present details of a prototype fiber feed for use on the Anglo-Australian Telescope (AAT) that uses a dedicated fiber-fed medium/high resolution (R > 10000) visible-band spectrograph to give integral field spectroscopy (IFS) of an extended object. A focal reducer couples light from the telescope to the close-packed lenslet array and fiber feed, allowing the spectrograph be used on other telescopes with the change of a single lens. By considering the properties of the fibers in the design of the spectrograph, an efficient design can be realised, and we present the first scientific results of a prototype spectrograph using a fiber feed with 37 spatial elements, namely the detection of Lithium confirming a brown dwarf candidate and IFS of the supernova remnant SN1987A.Comment: 41 pages, 15 figures, 3 tables; accepted by PAS

Adapting the International System of Units to the twenty-first century

We review the proposal of the International Committee for Weights and Measures (Comité International des Poids et Mesures, CIPM), currently being considered by the General Conference on Weights and Measures (Conférences Générales des Poids et Mesures, CGPM), to revise the International System of Units (Le Système International d’Unitès, SI). The proposal includes new definitions for four of the seven base units of the SI, and a new form of words to present the definitions of all the units. The objective of the proposed changes is to adopt definitions referenced to constants of nature, taken in the widest sense, so that the definitions may be based on what are believed to be true invariants. In particular, whereas in the current SI the kilogram, ampere, kelvin and mole are linked to exact numerical values of the mass of the international prototype of the kilogram, the magnetic constant (permeability of vacuum), the triple-point temperature of water and the molar mass of carbon-12, respectively, in the new SI these units are linked to exact numerical values of the Planck constant, the elementary charge, the Boltzmann constant and the Avogadro constant, respectively. The new wording used expresses the definitions in a simple and unambiguous manner without the need for the distinction between base and derived units. The importance of relations among the fundamental constants to the definitions, and the importance of establishing a mise en pratique for the realization of each definition, are also discussed

Rethinking critical criminology - A panel discussion

This paper takes the form of a report on the panel discussion held at the conclusion of the 1992 meetings of the European Group for the Study of Deviance and Social Control in Padua in September 1992. In the light of a perceived crisis of relevance for earlier, 1970s notions of critique in criminology, and in the context of a conference dedicated to the theme of human rights in a uniting Europe, eight panellists from Italy, England, and Canada via Ireland debated their different versions of the project of critical criminology in the last years of the twentieth century. Each of these presentations is summarised here, and an attempt is made to recognise the emergence of a debate between a "human rights criminology", eversensitive to the possibilities of repression and control in Fortress Europe, and an alternative perspective, predicated perhaps on some notion of Social Defence and a realist programme of crime prevention and control across free market Europe

El Niño and the delayed action oscillator

We study the dynamics of the El Niño phenomenon using the mathematical model of delayedaction oscillator (DAO). Topics such as the influence of the annual cycle, global warming, stochastic influences due to weather conditions and even off-equatorial heat-sinks can all be discussed using only modest analytical and numerical resources. Thus the DAO allows for a pedagogical introduction to the science of El Niño and La Niña while at the same time avoiding the need for large-scale computing resources normally associated with much more sophisticated coupled atmosphere-ocean general circulation models. It is an approach which is ideally suited for student projects both at high school and undergraduate level

Female urogenital dysfunction following total mesorectal excision for rectal cancer

BACKGROUND: The effect of Total Mesorectal Excision (TME) on sexual function in the male is well documented. However, there is little literature in female patients. The aim of this study was to review the pelvic autonomic nervous anatomy in the female and to perform a retrospective audit of urinary and sexual function in women following surgery for rectal cancer where TME had been performed. Urogenital dysfunction was assessed through interview and questionnaire. METHOD: Twenty-three questionnaires, eighteen returned, were sent to women with a mean age 65.5 yrs (range 34–86). All had undergone total mesorectal excision for rectal cancer between 1998–2001. Mean follow-up was 18.8 months (range 3–35). RESULTS: Preoperatively 5/18 (28%) were sexually active, 3/18 (17%) of patients described urinary frequency and nocturia and 7/18 (39%) described symptoms of stress incontinence prior to surgery. Postoperatively all sexually active patients remained active although all described some discomfort with penetration. Two of the patients sexually active described reduced libido secondary to the stoma. Postoperative urinary symptoms developed with 59% reporting the development of nocturia, 18% developed stress incontinence and one patient required a permanent catheter. Of those with symptoms, 80% persisted longer than three months from surgery. Symptoms were predominant in those patients with low rectal cancers, particularly those undergoing abdomino-perineal excision and in those who had previously undergone abdominal hysterectomy. CONCLUSION: The treatment of rectal cancer involves surgery to the pelvic floor. Despite nerve preservation this is associated with the development of worsening nocturia and stress incontinence. This is most marked in those patients who had previously undergone a hysterectomy. Further studies are warranted to assess the interaction with previous gynaecological surgery

A cryptic RNA-binding domain mediates Syncrip recognition and exosomal partitioning of miRNA targets

Exosomal miRNA transfer is a mechanism for cell-cell communication that is important in the immune response, in the functioning of the nervous system and in cancer. Syncrip/hnRNPQ is a highly conserved RNA-binding protein that mediates the exosomal partition of a set of miRNAs. Here, we report that Syncrip's amino-terminal domain, which was previously thought to mediate protein-protein interactions, is a cryptic, conserved and sequence-specific RNA-binding domain, designated NURR (N-terminal unit for RNA recognition). The NURR domain mediates the specific recognition of a short hEXO sequence defining Syncrip exosomal miRNA targets, and is coupled by a non-canonical structural element to Syncrip's RRM domains to achieve high-affinity miRNA binding. As a consequence, Syncrip-mediated selection of the target miRNAs implies both recognition of the hEXO sequence by the NURR domain and binding of the RRM domains 5′ to this sequence. This structural arrangement enables Syncrip-mediated selection of miRNAs with different seed sequences. © 2018 The Author(s)

Effective Temperatures of a Driven System Near Jamming

Fluctuations in a model of a sheared, zero-temperature foam are studied numerically. Five different quantities that reduce to the true temperature in an equilibrium thermal system are calculated. All five have the same shear-rate dependence, and three have the same value. Near the onset of jamming, the relaxation time is the same function of these three temperatures in the sheared system as of the true temperature in an unsheared system. These results imply that statistical mechanics is useful for the system and provide strong support for the concept of jamming.Comment: 4 pages, 4 postscript figure

Piston-ring film thickness: theory and experiment compared

A review of the published literature has demonstrated a large variability and discrepancies in the measured and predicted values of piston-ring lubricating film thickness in internal combustion engines. Only 2 papers have been found that compare experiments in firing engines directly with outputs from sophisticated ring-pack lubrication models. The agreement between theory and experiment in these comparisons was limited, possibly because of inadequacies in the models and/ or inaccuracies of measurement. This paper seeks to contribute to the literature by comparing accurately calibrated experimental measurements of piston-ring film thickness in a firing engine with predictions from an advanced, commercial software package alongside details of the systematic analysis of the measurement errors in this process. Suggestions on how measurement accuracy could be further improved are also given. Measurements of oil film thickness with an error (standard deviation) of +/-15% have been achieved. It is shown that this error can be reduced further, by changes in the design and installation of the sensors. Detailed experimental measurements of film thickness under the top compression ring in a firing petrol engine have been made and compared with the predictions from a commercial, state-of-the art modelling package. The agreement between theory and experiment is excellent throughout the stroke in most cases, but some significant differences are observed at the lower load conditions. These differences are as yet unexplained, but may be due to the sensor topography influencing the hydrodynamic lubrication, lubricant availability, out-of-roundness in the cylinder, or squeeze effects. This a topic that requires further stud