Limitations of Passive Protection of Quantum Information

The ability to protect quantum information from the effect of noise is one of the major goals of quantum information processing. In this article, we study limitations on the asymptotic stability of quantum information stored in passive N-qubit systems. We consider the effect of small imperfections in the implementation of the protecting Hamiltonian in the form of perturbations or weak coupling to a ground state environment. We prove that, regardless of the protecting Hamiltonian, there exists a perturbed evolution that necessitates a final error correcting step when the state of the memory is read. Such an error correction step is shown to require a finite error threshold, the lack thereof being exemplified by the 3D compass model. We go on to present explicit weak Hamiltonian perturbations which destroy the logical information stored in the 2D toric code in a time O(log(N)).Comment: 17 pages and appendice

How long can a quantum memory withstand depolarizing noise?

We investigate the possibilities and limitations of passive Hamiltonian protection of a quantum memory against depolarizing noise. Without protection, the lifetime of a single qubit is independent of N, the number of qubits composing the memory. In the presence of a protecting Hamiltonian, the lifetime increases at most logarithmically with N. We construct an explicit time-independent Hamiltonian which saturates this bound, exploiting the noise itself to achieve the protection.Comment: 4 pages, 2 figures. Accepted version, Journal-Ref adde

The bound state Aharonov-Bohm effect around a cosmic string revisited

In this article we observe that the self-adjoint extension of the Hamiltonian of a particle moving around a shielded cosmic string gives rise to a gravitational analogue of the bound state Aharonov-Bohm effect.Comment: 2 pages, no figure

Nuevo registro de Brontocoris tabidus (Hemiptera: Pentatomidae) atacando larvas de Heteroperreyia hubrichi (Hymenoptera: Pergidae)

Schinus terebinthifolia Raddi (Anacardiaceae) es un árbol perenne nativo de Argentina, Brasil, Paraguay y Uruguay, considerado actualmente una de las especies invasoras más agresivas y extendidas en Florida, Hawai y Texas (Estados Unidos). La avispa sierra defoliadora, Heteroperreyia hubrichi Malaise (Hymenoptera: Pergidae), es un agente potencial de control biológico para S. terebinthifolia. Durante inspecciones de campo recientes en el área de distribución nativa de S. terebinthifolia, ninfas y adultos de Brontocoris tabidus (Signoret) (Hemiptera: Pentatomidae) fueron encontrados predando larvas de H. hubrichi y Heteroperreyia n.? sp. sobre plantas de S. terebinthifolia en Argentina (Provincia de Misiones) y Brasil (Estado de Rio Grande do Sul) respectivamente. La depredación de B. tabidus sobre larvas de especies de Heteroperreyia constituye nuevos registros.Brazilian peppertree (Schinus terebinthifolia Raddi; Anacardiaceae) is a perennial tree native to Argentina, Brazil, Paraguay and Uruguay. Brazilian peppertree is one of the most aggressive and widespread invasive species in Florida, Hawaii, and Texas (USA). The defoliating sawfly, Heteroperreyia hubrichi Malaise (Hymenoptera: Pergidae), is a potential biological control agent for S. terebinthifolia. During surveys of plant use under natural conditions in the S. terebinthifolia native range, nymphs and adults of Brontocoris tabidus (Signoret) (Hemiptera: Pentatomidae) were found attacking H. hubrichi and Heteroperreyia n.? sp. larvae feeding on S. terebinthifolia in Argentina (Misiones Province) and Brazil (Rio Grande do Sul) respectively. The attack by B. tabidus on Heteroperreyia species constitutes new records.Fil: Mc Kay, Fernando. Fundación para el Estudio de Especies Invasivas; ArgentinaFil: Dellapé, Gimena. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Entomología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Dyer, Kisten. United States Department of Agriculture; Estados UnidosFil: Wheeler, Gregory. United States Department of Agriculture; Estados Unido

Thanatophoric dysplasia: case report of an autopsy complemented by postmortem computed tomographic study

Thanatophoric dysplasia (TD) is one of the most common lethal skeletal dysplasias, which was first designated as thanatophoric dwarfism and described in 1967. The authors report a case of a Caucasian girl with TD, born to a 31-year-old woman without comorbidities. The newborn presented respiratory distress immediately after delivery, progressing to death in less than 2 hours. An autopsy was carried out after postmortem tomographic examination. The autopsy findings depicted extensive malformations of the skeletal system and the brain. The aim of this report is to discuss the pathogenesis and correlate the morphologic features of TD that were disclosed at the tomography and the autopsy

Differences between postmortem computed tomography and conventional autopsy in a stabbing murder case

Objective: The aim of the present work is to analyze the differences and similarities between the elements of a conventional autopsy and images obtained from postmortem computed tomography in a case of a homicide stab wound. Method: Comparison between the findings of different methods: autopsy and postmortem computed tomography. Results: In some aspects, autopsy is still superior to imaging, especially in relation to external examination and the description of lesion vitality. However, the findings of gas embolism, pneumothorax and pulmonary emphysema and the relationship between the internal path of the instrument of aggression and the entry wound are better demonstrated by postmortem computed tomography. Conclusions: Although multislice computed tomography has greater accuracy than autopsy, we believe that the conventional autopsy method is fundamental for providing evidence in criminal investigations

To which world regions does the valence–dominance model of social perception apply?

Over the past 10 years, Oosterhof and Todorov’s valence–dominance model has emerged as the most prominent account of how people evaluate faces on social dimensions. In this model, two dimensions (valence and dominance) underpin social judgements of faces. Because this model has primarily been developed and tested in Western regions, it is unclear whether these findings apply to other regions. We addressed this question by replicating Oosterhof and Todorov’s methodology across 11 world regions, 41 countries and 11,570 participants. When we used Oosterhof and Todorov’s original analysis strategy, the valence–dominance model generalized across regions. When we used an alternative methodology to allow for correlated dimensions, we observed much less generalization. Collectively, these results suggest that, while the valence–dominance model generalizes very well across regions when dimensions are forced to be orthogonal, regional differences are revealed when we use different extraction methods and correlate and rotate the dimension reduction solution

Why are we misdiagnosing urinary tract infection in older patients? A qualitative inquiry and roadmap for staff behaviour change in the emergency department

Purpose - The aim of this study was to identify the psychological and behavioural factors influencing clinicians managing older people with possible UTI in urgent care settings, and to develop an improvement roadmap. Methods - Michie’s behaviour change wheel and COM-B (Capability, Opportunity, Motivation, Behaviour Change) models were used as the theoretical basis for this study. Semi-structured interviews were undertaken with 21 purposively selected medical and nursing staff in a large urban emergency department in the East Midlands, United Kingdom. Analysis was informed by the framework approach. A participatory design approach was used to develop an improvement roadmap. Results - Key themes emerging from the semi-structured interviews included lack of knowledge on the role of urine dipstick testing, bias towards older people, automatic testing, time and resource constraints, pressures from peers and patients, and fear of the legal consequences of inaction. A thematic networks map indicated complex interactions between psychological and behavioural factors. Among more than 50 different intervention ideas identified by the workshop participants, two interventions were prioritised for implementation: i) controlling the use of dip stick urine tests; ii) providing individualised feedback to staff regarding the outcomes of patients diagnosed and treated for UTI. Conclusions - Psychological and behavioural factors play a significant role in the misdiagnosis of UTI in older people. Systematic approaches incorporating these factors might improve patient outcomes. Future studies should focus on implementation and evaluating their effectiveness and sustainability