11,208 research outputs found
Crystal field analysis of Dy and Tm implanted silicon for photonic and quantum technologies
We report the lattice site and symmetry of optically active Dy3+
and Tm3+ implanted Si. Local symmetry was determined by fitting crystal
field parameters (CFPs), corresponding to various common symmetries, to
the ground state splitting determined by photoluminescence measurements.
These CFP values were then used to calculate the splitting of every J
manifold. We find that both Dy and Tm ions are in a Si substitution site
with local tetragonal symmetry. Knowledge of rare-earth ion symmetry is
important in maximising the number of optically active centres and for
quantum technology applications where local symmetry can be used to
control decoherence
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Paediatric gastroenterology evaluation of overweight and obese children referred from primary care for suspected non-alcoholic fatty liver disease.
BackgroundScreening overweight and obese children for non-alcoholic fatty liver disease (NAFLD) is recommended by paediatric and endocrinology societies. However, gastroenterology societies have called for more data before making a formal recommendation.AimTo determine whether the detection of suspected NAFLD in overweight and obese children through screening in primary care and referral to paediatric gastroenterology resulted in a correct diagnosis of NAFLD.MethodsInformation generated in the clinical evaluation of 347 children identified with suspected NAFLD through screening in primary care and referral to paediatric gastroenterology was captured prospectively. Diagnostic outcomes were reported. The diagnostic performance of two times the upper limit of normal (ULN) for alanine aminotransferase (ALT) was assessed.ResultsNon-alcoholic fatty liver disease was diagnosed in 55% of children identified by screening and referral. Liver disease other than NAFLD was present in 18% of those referred. Autoimmune hepatitis was the most common alternative diagnosis. Children with NAFLD had significantly (P < 0.05) higher screening ALT (98 ± 95) than children with liver disease other than NAFLD (86 ± 74). Advanced fibrosis was present in 11% of children. For the diagnosis of NAFLD, screening ALT two times the clinical ULN had a sensitivity of 57% and a specificity of 71%.ConclusionsScreening of overweight and obese children in primary care for NAFLD with referral to paediatric gastroenterology has the potential to identify clinically relevant liver pathology. Consensus is needed on how to value the risk and rewards of screening and referral, to identify children with liver disease in the most appropriate manner
An evaluation of two distributed deployment algorithms for Mobile Wireless Sensor Networks
Deployment is important in large wireless sensor networks (WSN), specially because nodes may fall due to failure or battery issues. Mobile WSN cope with deployment and reconfiguration at the same time: nodes may move autonomously: i) to achieve a good area coverage; and ii) to distribute as homogeneously as possible. Optimal distribution is computationally expensive and implies high tra c load, so local, distributed approaches may be preferable. This paper presents an experimental evaluation of role-based and behavior based ones. Results show that the later
are better, specially for a large number of nodes in areas with obstacles.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech
Checking Interaction-Based Declassification Policies for Android Using Symbolic Execution
Mobile apps can access a wide variety of secure information, such as contacts
and location. However, current mobile platforms include only coarse access
control mechanisms to protect such data. In this paper, we introduce
interaction-based declassification policies, in which the user's interactions
with the app constrain the release of sensitive information. Our policies are
defined extensionally, so as to be independent of the app's implementation,
based on sequences of security-relevant events that occur in app runs. Policies
use LTL formulae to precisely specify which secret inputs, read at which times,
may be released. We formalize a semantic security condition, interaction-based
noninterference, to define our policies precisely. Finally, we describe a
prototype tool that uses symbolic execution to check interaction-based
declassification policies for Android, and we show that it enforces policies
correctly on a set of apps.Comment: This research was supported in part by NSF grants CNS-1064997 and
1421373, AFOSR grants FA9550-12-1-0334 and FA9550-14-1-0334, a partnership
between UMIACS and the Laboratory for Telecommunication Sciences, and the
National Security Agenc
Performance of mechanically shaken indirect contact atmospheric dryer in drying pastelike materials
Pastelike materials are encountered in many technological processes in chemical, pharmaceutical, foodstuff and natural product industries. The most important factor in the drying of this type of materials is the nature of the moisture bonding that occurs. Because of the different characteristics of pastes, it is impossible to recommend a universal type of dryer for all of these materials. Some of the dryers available provide only indirect contact with the drying agent (heat) and also maintain constant moisture with a system of rotating paddles. We evaluated the performance of this type by studying the dryer kinetics curves for ground coffee under a variety of operational conditions of moisture load of material, temperature of the heating plate, intensity of the mechanical mixing of the moisture material, and initial moisture. The effects of these parameters (except for moisture) were studied using a 2 3 factorial design. According the analyses of the kinetics drying curves, was observed that the increase in the temperature of the plate and rotation as well as the decrease in the load facilitates more effective removal of moisture. In statistical analysis was determined that the load of the material and the heating plate temperature influence the final moisture content of the material and plate temperature modifies the final temperature of the solid. Also, was suggested linear models from the factorial design to describe the process of drying coffee grounds satisfactorily.21348749
Silicon-Modified rare-earth transitions - a new route to Near- and Mid-IR Photonics
Silicon underpins microelectronics but lacks the photonic capability needed for next-generation systems and currently relies on a highly undesirable hybridization of separate discrete devices using direct band gap semiconductors. Rare-earth (RE) implantation is a promising approach to bestow photonic capability to silicon but is limited to internal RE transition wavelengths. Reported here is the first observation of direct optical transitions from the silicon band edge to internal f-levels of implanted REs (Ce, Eu, and Yb); this overturns previously held assumptions about the alignment of RE levels to the silicon band gap. The photoluminescence lines are massively redshifted to several technologically useful wavelengths and modeling of their splitting indicates that they must originate from the REs. Eu-implanted silicon devices display a greatly enhanced electroluminescence efficiency of 8%. Also observed is the first crystal field splitting in Ce luminescence. Mid-IR silicon photodetectors with specific detectivities comparable to existing state-of-the-art mid-IR detectors are demonstrated
Securing a Future for China's Wild Plant Resources
China harbors one of the most species-rich floras in the world. This plant diversity is currently severely threatened by high levels of habitat degradation and unsustainable resource extraction, the country's exceptionally fast economic growth, an uncontrolled increase in tourism, invasive species, and climate change. Furthermore, China's current system of protected areas is ineffective at conserving the country's plant resources, with low levels of enforcement and only a few small reserves located in both the most phytodiverse regions and in areas facing the highest anthropogenic pressure. Seven strategic steps are required in order to secure a future for China's wild plants, including surveys to establish current species distributions and threat levels, the creation of an effective protected-area system focused on quality rather than quantity, resettlement of parts of the scattered rural population, control of the illegal export trade and invasive species, and a streamlining of administrative responsibilities and capacity building in conservation
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