1,738 research outputs found
Quantum Correlations in Multipartite Quantum Systems
We review some concepts and properties of quantum correlations, in particular
multipartite measures, geometric measures and monogamy relations. We also
discuss the relation between classical and total correlationsComment: to be published as a chapter of the book "Lectures on general quantum
correlations and their applications" edited by F. Fanchini, D. Soares-Pinto,
and G. Adesso (Springer, 2017
Why should we care about quantum discord?
Entanglement is a central feature of quantum theory. Mathematical properties
and physical applications of pure state entanglement make it a template to
study quantum correlations. However, an extension of entanglement measures to
mixed states in terms of separability does not always correspond to all the
operational aspects. Quantum discord measures allow an alternative way to
extend the idea of quantum correlations to mixed states. In many cases these
extensions are motivated by physical scenarios and quantum information
protocols. In this chapter we discuss several settings involving correlated
quantum systems, ranging from distributed gates to detectors testing quantum
fields. In each setting we show how entanglement fails to capture the relevant
features of the correlated system, and discuss the role of discord as a
possible alternative.Comment: Written for "Lectures on general quantum correlations and their
applications
Choosing a Survey Sample When Data on the Population Are Limited: A Method Using Global Positioning Systems and Aerial and Satellite Photographs
Background
Various methods have been proposed for sampling when data on the population are limited. However, these methods are often biased. We propose a new method to draw a population sample using Global Positioning Systems and aerial or satellite photographs.
Results
We randomly sampled Global Positioning System locations in designated areas. A circle was drawn around each location with radius representing 20 m. Buildings in the circle were identified from satellite photographs; one was randomly chosen. Interviewers selected one household from the building, and interviews were conducted with eligible household members.
Conclusions
Participants had known selection probabilities, allowing proper estimation of parameters of interest and their variances. The approach was made possible by recent technological developments and access to satellite photographs.
 
Optimal use of visual information in adolescents and young adults with developmental coordination disorder
Recent reports offer contrasting views on whether or not the use of online visual control is impaired in individuals with developmental coordination disorder (DCD). This study explored the optimal temporal basis for processing and using visual information in adolescents and young adults with DCD. Participants were 22 adolescents and young adults (12 males and 10 females; M = 19 years, SD = 3). Half had been diagnosed with DCD as children and still performed poorly on the movement assessment battery for children (DCD group; n = 11), and half reported typical development (TD group; n = 11) and were age- and gender-matched with the DCD group. We used performance on a steering task as a measure of information processing and examined the use of advance visual information. The conditions varied the duration of advance visual information: 125, 250, 500, 750, and 1,000 ms. With increased duration of advance visual information, the TD group showed a pattern of linear improvement. For the DCD group, however, the pattern was best described by a U-curve where optimal performance occurred with about 750 ms of advance information. The results suggest that the DCD group has an underlying preference for immediate online processing of visual information. The exact timing for optimal online control may depend crucially on the task, but too much advance information is detrimental to performance
Engaging with community researchers for exposure science: lessons learned from a pesticide biomonitoring study
A major challenge in biomonitoring studies with members of the general public is ensuring their continued involvement throughout the necessary length of the research. The paper presents evidence on the use of community researchers, recruited from local study areas, as a mechanism for ensuring effective recruitment and retention of farmer and resident participants for a pesticides biomonitoring study. The evidence presented suggests that community researchers' abilities to build and sustain trusting relationships with participants enhanced the rigour of the study as a result of their on-the-ground responsiveness and flexibility resulting in data collection beyond targets expected
FindFoci: a focus detection algorithm with automated parameter training that closely matches human assignments, reduces human inconsistencies and increases speed of analysis
Accurate and reproducible quantification of the accumulation of proteins into foci in cells is essential for data interpretation and for biological inferences. To improve reproducibility, much emphasis has been placed on the preparation of samples, but less attention has been given to reporting and standardizing the quantification of foci. The current standard to quantitate foci in open-source software is to manually determine a range of parameters based on the outcome of one or a few representative images and then apply the parameter combination to the analysis of a larger dataset. Here, we demonstrate the power and utility of using machine learning to train a new algorithm (FindFoci) to determine optimal parameters. FindFoci closely matches human assignments and allows rapid automated exploration of parameter space. Thus, individuals can train the algorithm to mirror their own assignments and then automate focus counting using the same parameters across a large number of images. Using the training algorithm to match human assignments of foci, we demonstrate that applying an optimal parameter combination from a single image is not broadly applicable to analysis of other images scored by the same experimenter or by other experimenters. Our analysis thus reveals wide variation in human assignment of foci and their quantification. To overcome this, we developed training on multiple images, which reduces the inconsistency of using a single or a few images to set parameters for focus detection. FindFoci is provided as an open-source plugin for ImageJ
Factors associated with post-traumatic stress disorder and depression amongst internally displaced persons in northern Uganda
BACKGROUND: The 20 year war in northern Uganda between the Lord's Resistance Army and the Ugandan government has resulted in the displacement of up to 2 million people within Uganda. The purpose of the study was to measure rates of post-traumatic stress disorder (PTSD) and depression amongst these internally displaced persons (IDPs), and investigate associated demographic and trauma exposure risk factors. METHODS: A cross-sectional multi-staged, random cluster survey with 1210 adult IDPs was conducted in November 2006 in Gulu and Amuru districts of northern Uganda. Levels of exposure to traumatic events and PTSD were measured using the Harvard Trauma Questionnaire (original version), and levels of depression were measured using the Hopkins Symptom Checklist-25. Multivariate logistic regression was used to analyse the association of demographic and trauma exposure variables on the outcomes of PTSD and depression. RESULTS: Over half (54%) of the respondents met symptom criteria for PTSD, and over two thirds (67%) of respondents met symptom criteria for depression. Over half (58%) of respondents had experienced 8 or more of the 16 trauma events covered in the questionnaire. Factors strongly linked with PTSD and depression included gender, marital status, distance of displacement, experiencing ill health without medical care, experiencing rape or sexual abuse, experiencing lack of food or water, and experiencing higher rates of trauma exposure. CONCLUSION: This study provides evidence of exposure to traumatic events and deprivation of essential goods and services suffered by IDPs, and the resultant effect this has upon their mental health. Protection and social and psychological assistance are urgently required to help IDPs in northern Uganda re-build their lives
The CACCC-binding protein KLF3/BKLF represses a subset of KLF1/EKLF target genes and is required for proper erythroid maturation in vivo
The CACCC-box binding protein erythroid Kruppel-like factor (EKLF/KLF1) is a master regulator that directs the expression of many important erythroid genes. We have previously shown that EKLF drives transcription of the gene for a second KLF, basic Kruppel-like factor, or KLF3. We have now tested the in vivo role of KLF3 in erythroid cells by examining Klf3 knockout mice. KLF3-deficient adults exhibit a mild compensated anemia, including enlarged spleens, increased red pulp, and a higher percentage of erythroid progenitors, together with elevated reticulocytes and abnormal erythrocytes in the peripheral blood. Impaired erythroid maturation is also observed in the fetal liver. We have found that KLF3 levels rise as erythroid cells mature to become TER119(+). Consistent with this, microarray analysis of both TER119(-) and TER119(+) erythroid populations revealed that KLF3 is most critical at the later stages of erythroid maturation and is indeed primarily a transcriptional repressor. Notably, many of the genes repressed by KLF3 are also known to be activated by EKLF. However, the majority of these are not currently recognized as erythroid-cell-specific genes. These results reveal the molecular and physiological function of KLF3, defining it as a feedback repressor that counters the activity of EKLF at selected target genes to achieve normal erythropoiesis
Entanglement distribution and quantum discord
Establishing entanglement between distant parties is one of the most
important problems of quantum technology, since long-distance entanglement is
an essential part of such fundamental tasks as quantum cryptography or quantum
teleportation. In this lecture we review basic properties of entanglement and
quantum discord, and discuss recent results on entanglement distribution and
the role of quantum discord therein. We also review entanglement distribution
with separable states, and discuss important problems which still remain open.
One such open problem is a possible advantage of indirect entanglement
distribution, when compared to direct distribution protocols.Comment: 7 pages, 2 figures, contribution to "Lectures on general quantum
correlations and their applications", edited by Felipe Fanchini, Diogo
Soares-Pinto, and Gerardo Adess
Quantum Discord and entropic measures of quantum correlations: Optimization and behavior in finite spin chains
We discuss a generalization of the conditional entropy and one-way
information deficit in quantum systems, based on general entropic forms. The
formalism allows to consider simple entropic forms for which a closed
evaluation of the associated optimization problem in qudit-qubit systems is
shown to become feasible, allowing to approximate that of the quantum discord.
As application, we examine quantum correlations of spin pairs in the exact
ground state of finite spin chains in a magnetic field through the quantum
discord and information deficit. While these quantities show a similar
behavior, their optimizing measurements exhibit significant differences, which
can be understood and predicted through the previous approximations. The
remarkable behavior of these quantities in the vicinity of transverse and
non-transverse factorizing fields is also discussed.Comment: 10 pages, 3 figure
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