Compact set of invariants characterizing graph states of up to eight qubits

The set of entanglement measures proposed by Hein, Eisert, and Briegel for n-qubit graph states [Phys. Rev. A 69, 062311 (2004)] fails to distinguish between inequivalent classes under local Clifford operations if n > 6. On the other hand, the set of invariants proposed by van den Nest, Dehaene, and De Moor (VDD) [Phys. Rev. A 72, 014307 (2005)] distinguishes between inequivalent classes, but contains too many invariants (more than 2 10^{36} for n=7) to be practical. Here we solve the problem of deciding which entanglement class a graph state of n < 9 qubits belongs to by calculating some of the state's intrinsic properties. We show that four invariants related to those proposed by VDD are enough for distinguishing between all inequivalent classes with n < 9 qubits.Comment: REVTeX4, 9 pages, 1 figur

Experimental fully contextual correlations

Quantum correlations are contextual yet, in general, nothing prevents the existence of even more contextual correlations. We identify and test a noncontextuality inequality in which the quantum violation cannot be improved by any hypothetical postquantum theory, and use it to experimentally obtain correlations in which the fraction of noncontextual correlations is less than 0.06. Our correlations are experimentally generated from the results of sequential compatible tests on a four-state quantum system encoded in the polarization and path of a single photon.Comment: REVTeX4, 6 pages, 3 figure

Numerical study of efficiencies for box type solar cooker with internal reflectors

En este trabajo se muestran los resultados del estudio de las eficiencias termodinámicas de 1.a y 2.a ley aplicadas a 4 arreglos diferentes de estufas solares de tipo caja con reflectores internos. La estufa solar tiene 2 vidrios en su cubierta para disminuir la pérdida de calor por radiación y convección, y crear así el efecto invernadero. El interior de la estufa tiene espejos colocados a diferentes ángulos para dirigir la radiación solar hacia un recipiente con agua que se encuentra también dentro de la estufa. Los resultados obtenidos están basados en las temperaturas de calentamiento del agua, las cuales fueron obtenidas por medio de una simulación numérica que permite comparar los 4 arreglos de estufas solares bajo condiciones idénticas. El tratamiento de los resultados revela que la cantidad de energía que impacta en las estufas solares no es aprovechada de manera adecuada para los fines de calentamiento de agua. La mayor parte de la energía aprovechable se almacena en los vidrios de la tapa, lo que evidencia la necesidad de trabajar en el desarrollo de mejores materiales para mejorar tal situación.In this work, results of efficiencies for first and second law of thermodynamics applied to four box-type solar cookers with internal reflectors are shown. The solar cooker has two glasses on its cover to diminish the losses of heat for radiation and convection, besides creating the effect hothouse inside the cooker. The interior of the cooker has flat mirrors placed at different angles to reflect the solar radiation toward a recipient with water inside the cooker. The obtained results are based on heating water temperatures which were obtained by means of numeric simulation, allowing comparison under identical conditions of four solar cookers. The treatment of the results revealed that the quantity of energy that impacts on the solar cookers is not used in right way for the heating water ends. Most of the profitable energy is stored in the glasses of the cover, what evidences the necessity to work in the development of better materials to diminish such situation.Peer Reviewe

Prevalence of apical periodontitis and frequency of root canal treatments in liver transplant candidates

Aim: The purpose of this study was to investigate the prevalence of apical periodontitis (AP) and endodontic treatment in liver transplant candidates and control healthy subjects. Material and Methods: A descriptive cross-sectional study. Forty two liver transplant candidates (LTC) (study group) and 42 control subjects. Digital panoramic radiographs where used. Periapical status was scored according to the periapical index (PAI). Results were analysed statistically using the Chi-squared test and logistic regression. Results: Radiographic signs of AP in one or more teeth was found in 79% of patients in the study group and in 50% of control subjects (p = 0.008; OR = 3.7; C. I. 95% = 1.4 - 9.5). One or more root-filled teeth (RFT) were found in 19% and 62% of study and control subjects, respectively (p = 0.0001; OR = 0.14; 95% C. I. = 0.05 - 0.38). Among LTC patients 14.7% of the teeth had AP, whereas in the control subjects 4.2% of teeth were affected (p= 0.0002). The percentage of RFT in the study and control groups was 1.5% and 6.8%, respectively (p = 0.0002). Conclusions: Liver transplant candidates have significantly higher prevalence of radiographic periapical lesions and lower frequency of RFT than controls healthy subjects

Problematising high-stakes assessment in statistics.

Statistics emerged as a discipline to address pressing practical problems. In the UK, this has not been reflected in school statistics curricula, where students often work with small-scale invented data to develop mastery of statistical technique. Recent curriculum reforms set out to improve this situation; students are expected to work in class with a large authentic data set, and to demonstrate appropriate skills on high-stakes assessment. Here, we analyse all the first set of examination papers containing statistics for the new GCE qualification, and also questions using statistical graphs from the GCSE qualifications in summer 2017. We show that there is very little emphasis on statistical skills such as interpreting data and drawing conclusions, and a great deal of emphasis on technical skills. Contexts are (for the most part) banal. Several questions ask students to use inappropriate procedures. We believe systemic flaws have resulted in assessment which is not fit for purpose. We call for curriculum reform, and offer examples of how things might be done better both in curriculum and in assessment

Artificial Modifications of the Coast In Response to the \u3ci\u3eDeepwater Horizon\u3c/i\u3e Oil Spill: Quick Solutions or Long-Term Liabilities?

The Deepwater Horizon oil spill threatened many coastal ecosystems in the Gulf of Mexico during the spring and summer of 2010. Mitigation strategies included the construction of barrier sand berms, the restriction or blocking of inlets, and the diversion of freshwater from rivers to the coastal marshes and into the ocean, in order to flush away the oil, on the premise that these measures could reduce the quantity of oil reaching sensitive coastal environments such as wetlands or estuaries. These projects result in changes to the ecosystems that they were intended to protect. Long-term effects include alterations of the hydrological and ecological characteristics of estuaries, changes in sediment transport along the coastal barrier islands, the loss of sand resources, and adverse impacts to benthic and pelagic organisms. Although there are no easy solutions for minimizing the impacts of the Deepwater Horizon disaster on coastal ecosystems, we recommend that federal, state, and local agencies return to the strategic use of long-term restoration plans for this region

Synergy between magneto-rheological fluids and aluminum foams. Prospective alternative for seismic damping

This is the accepted manuscript. Access to the published article can be gained at: http://jim.sagepub.com/cgi/reprint/1045389X15596624v1.pdf?ijkey=SyFHNQwE4XMQqBF&keytype=finiteThis article presents the experimental study of a preliminary investigation of a seismic damper device aimed at improving the behavior of structures when subjected to earthquakes. The damper is the result of a binomial material formed by aluminum foam with pores 1 mm in diameter, wetted by a magnetorheological fluid (MRF). The objective of the present work is to explore the synergy between the two components in a magnetorheological test, and to evaluate the effect of the Al foam pores in the structure buildup of the fluid. The analysis is completed with a compressive test carried out on the MRF-filled foam in the presence of a magnetic field. This kind of test demonstrates that the deformation of the foam for very small loads is limited by the hardening of the fluid because of its MR response. The results of this research suggest that there is a mutual benefit between the components of the device, presumably leading to an enhanced dissipation of vibration energy.Proyectos PE2012-FQM694 (Junta de Andalucía, Spain), FIS2013-47666-C3-1-R (MINECO, Spain), SENER-CONACYT "151496" (UNAM Mexico), CONACYT National Quality Graduate Progra

An Initial Framework for Understanding the Resilience of Aquifers to Groundwater Pumping

Groundwater stored in aquifers experiences a wide variety of natural, induced and/or anthropogenic disturbances. Among them, groundwater extraction is the main disturbance that affects most of the aquifers in the world. Aquifer’s resilience, understood as the potential of the aquifer to sustain disturbances on the long term and to guarantee essential qualities and functions, provides a key tool when assessing sustainable groundwater management alternatives. The aim of this work is to illustrate an aquifer resilience framework that can support groundwater sustainable management. A theoretical framework is based on the identification of the key variables that parameterize the quantitative and qualitative responses of the groundwater flow system to pumping. An example from the literature based in Denmark is provided as an illustration of the proposed framework. The results show that long-term high quality data are essential to make a step further in aquifers dynamic responses. The quantitative understanding of the aquifer’s behavior before, during and after groundwater extraction provides a valuable source of information in order to identify thresholds of change (tipping points, transitions or regime shifts) which could permit pro-active groundwater management decisions. Moreover, a deeper understanding on the aquifer’s dynamics provides useful information in order to avert threats that may put the sustainability of the system at risk

Integrating current and historical water chemistry data with long-term piezometric records to develop a regional-scale conceptual flow model: Las Salinas spring, Medina del Campo, Spain

Study region: Old Las Salinas spring in Medina del Campo, Duero river basin, central Spain. Study focus: Medina del Campo groundwater body (MCGWB) is a multilayer semiconfined aquifer subject to intensive pumping since the 1970’s, where the current existence of spas where there used to be traditional baths could confirm the existence of deep groundwater flow paths. The old spring of Las Salinas (OSLS) is a saline anomaly in an aquifer with predominance of CaCO3H waters whose occurrence has not yet been formally explained. Long-term geological, geophysical, hydrogeological and hydrochemical records were integrated and complemented with field work to clarify its existence. New hydrological insights for the region: Outcomes led to the conclusion that the hydrochemistry of the Olmedo and Palacio de las Salinas salt baths is associated with the existence of a major threshold in the impervious basement of the aquifer, which intercepted deep regional groundwater flow and caused upwelling to the surface under unperturbed conditions. These results allow for the development of a conceptual flow model at the regional scale that explains the changes in natural water chemistry that have been identified in recent decades