Adiabatic critical quantum metrology cannot reach the Heisenberg limit even when shortcuts to adiabaticity are applied

We show that the quantum Fisher information attained in an adiabatic approach to critical quantum metrology cannot lead to the Heisenberg limit of precision and therefore regular quantum metrology under optimal settings is always superior. Furthermore, we argue that even though shortcuts to adiabaticity can arbitrarily decrease the time of preparing critical ground states, they cannot be used to achieve or overcome the Heisenberg limit for quantum parameter estimation in adiabatic critical quantum metrology. As case studies, we explore the application of counter-diabatic driving to the Landau-Zener model and the quantum Rabi model.Comment: 22 pages, 6 figure

Pictures of the past : Benjamin and Barthes on photography.

This paper explores the key moments in Benjamin’s and Barthes’s analyses of the cultural significance of the photograph. For Benjamin these are; the optical unconscious, the transmission of aura, the representation of cultural and political decay and proto-surrealist political commentary. For Barthes they are; the techniques of the photographer, the studium, the punctum and the ecstasy of the image. These rather different approaches to photography reveal a common concern with history. Both authors have written about the nature of historical understanding and photography has provided both with a powerful metaphor. What emerges from their analyses of photographs is that each evokes a double moment of historical awareness; of being both in the present and in the past. For Benjamin this is the ‘spark of contingency’ with which the aura of past existence shines in the present. For Barthes it is the ‘ça-a-été’, the emotional stab of awareness that what is present and visible in the photograph is irretrievably lost in the past

Intestinal Fatty Acid Binding Protein as a Predictor of Early Mesenteric Injury Preceding Clinical Presentation:A Case Report

Introduction: Diagnosing non-occlusive mesenteric ischaemia (NOMI) in patients is complicated, due to poor signs and symptoms and non-specific laboratory tests, leading to a high mortality rate. This case study presents the rare case of a patient who developed mesenteric ischaemia after an emergency thoracic endovascular aneurysm repair (TEVAR) for a type B aortic dissection (TBAD) and peri-operative cardiogenic shock. Study outcomes revealed that intestinal fatty acid binding protein (I-FABP) identified early mucosal damage two days before the clinical presentation. Report: A 43 year old male patient was admitted to the emergency department with an acute TBAD and a dissection of the superior mesenteric artery (SMA), for which TEVAR was performed with additional stent placement in the SMA. Peri-operatively, the patient went into cardiogenic shock with a sustained period of hypotension. Post-operatively, the plasma I-FABP levels were measured prospectively, revealing an initial increase on post-operative day five (551.1 pg/mL), which continued beyond day six (610.3 pg/mL). On post-operative day seven, the patient developed a fever and demonstrated signs of peritonitis and bowel perforation. He underwent an emergency laparotomy, followed by an ileocaecal resection (&lt;100 cm) with a transverse ileostomy. Pathological analysis confirmed the diagnosis of mesenteric ischaemia. Discussion: The diagnosis of NOMI in critically ill patients is often complicated, and the currently available diagnostic markers lack the specificity and sensitivity to detect early intestinal injury. This case report highlights that elevated I-FABP in plasma levels may indicate the presence of early mesenteric injury. Further research needs to be conducted before I-FABP can be applied in daily practice.</p

Estimating direct rebound effects for personal automotive travel in Great Britain

Direct rebound effects result from increased consumption of cheaper energy services. For example, more fuel-efficient cars encourage more car travel. This study is the first to quantify this effect for personal automotive travel in Great Britain. We use aggregate time-series data on transport activity, fuel consumption and other relevant variables over the period 1970-2011 and estimate the direct rebound effect from the elasticity of vehicle kilometres with respect to: a) vehicle fuel efficiency (km/MJ); b) the fuel cost of driving (£/km); and c) road fuel prices (£/MJ). We estimate a total of 54 models, paying careful attention to methodological issues and model diagnostics. Taking changes in fuel efficiency as the explanatory variable, we find no evidence of a long-run direct rebound effect in Great Britain over this period. However, taking changes in either the fuel cost of driving or fuel prices as the explanatory variable we estimate a direct rebound effect in the range 10% to 27% with a mean of 18%. This estimate is consistent with the results of US studies and suggests that one fifth of the potential fuel savings from improved car fuel efficiency may have been eroded through increased driving. We also show how the normalisation of distance travelled (per capita, per adult or per driver) affects the results obtained

Mast cells protect from post-traumatic spinal cord damage in mice by degrading inflammation-associated cytokines via mouse mast cell protease 4

AbstractMast cells (MCs) are found abundantly in the central nervous system and play a complex role in neuroinflammatory diseases such as multiple sclerosis and stroke. In the present study, we show that MC-deficient KitW-sh/W-sh mice display significantly increased astrogliosis and T cell infiltration as well as significantly reduced functional recovery after spinal cord injury compared to wildtype mice. In addition, MC-deficient mice show significantly increased levels of MCP-1, TNF-α, IL-10 and IL-13 protein levels in the spinal cord. Mice deficient in mouse mast cell protease 4 (mMCP4), an MC-specific chymase, also showed increased MCP-1, IL-6 and IL-13 protein levels in spinal cord samples and a decreased functional outcome after spinal cord injury. A degradation assay using supernatant from MCs derived from either mMCP4−/− mice or controls revealed that mMCP4 cleaves MCP-1, IL-6, and IL-13 suggesting a protective role for MC proteases in neuroinflammation. These data show for the first time that MCs may be protective after spinal cord injury and that they may reduce CNS damage by degrading inflammation-associated cytokines via the MC-specific chymase mMCP4

Spectral Theory of Sparse Non-Hermitian Random Matrices

Sparse non-Hermitian random matrices arise in the study of disordered physical systems with asymmetric local interactions, and have applications ranging from neural networks to ecosystem dynamics. The spectral characteristics of these matrices provide crucial information on system stability and susceptibility, however, their study is greatly complicated by the twin challenges of a lack of symmetry and a sparse interaction structure. In this review we provide a concise and systematic introduction to the main tools and results in this field. We show how the spectra of sparse non-Hermitian matrices can be computed via an analogy with infinite dimensional operators obeying certain recursion relations. With reference to three illustrative examples --- adjacency matrices of regular oriented graphs, adjacency matrices of oriented Erd\H{o}s-R\'{e}nyi graphs, and adjacency matrices of weighted oriented Erd\H{o}s-R\'{e}nyi graphs --- we demonstrate the use of these methods to obtain both analytic and numerical results for the spectrum, the spectral distribution, the location of outlier eigenvalues, and the statistical properties of eigenvectors.Comment: 60 pages, 10 figure