3,503 research outputs found

    Mutual information between reflected and transmitted speckle images

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    We study theoretically the mutual information between reflected and transmitted speckle patterns produced by wave scattering from disordered media. The mutual information between the two speckle images recorded on an array of N detection points (pixels) takes the form of long-range intensity correlation loops, that we evaluate explicitly as a function of the disorder strength and the Thouless number g. Our analysis, supported by extensive numerical simulations, reveals a competing effect of cross-sample and surface spatial correlations. An optimal distance between pixels is proven to exist, that enhances the mutual information by a factor Ng compared to the single-pixel scenario.Comment: 5 pages, 4 figures, + S

    Correlations between reflected and transmitted intensity patterns emerging from opaque disordered media

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    The propagation of monochromatic light through a scattering medium produces speckle patterns in reflection and transmission, and the apparent randomness of these patterns prevents direct imaging through thick turbid media. Yet, since elastic multiple scattering is fundamentally a linear and deterministic process, information is not lost but distributed among many degrees of freedom that can be resolved and manipulated. Here we demonstrate experimentally that the reflected and transmitted speckle patterns are correlated, even for opaque media with thickness much larger than the transport mean free path, proving that information survives the multiple scattering process and can be recovered. The existence of mutual information between the two sides of a scattering medium opens up new possibilities for the control of transmitted light without any feedback from the target side, but using only information gathered from the reflected speckle.Comment: 6 pages, 4 figure

    "We've always known who we are": Belonging in the Poarch Band of Creek Indians.

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    This dissertation focuses on the history and identity of the Poarch Band of Creek Indians of Alabama. This work contributes to the larger body of scholarship that challenges the invisibility of Native Americans in the East and the South. The dissertation describes the economic conditions of the Poarch Creeks from the early twentieth century to the present. I trace the process Poarch went through in order to gain access to equal educational opportunities in the segregated South. I also discuss the integration of local white schools with Indian children. Two chapters of this dissertation are devoted to the way in which the Poarch Creek define kinship and tribal membership. I analyze the way in which blood quantum is used to identify members of the Poarch Band of Creek Indians. I also examine how the tribe’s legal definitions of tribal members differ from the broader Poarch community’s understanding of who belongs in the community and who is deserving of current tribal member benefits. Drawing on Janet Carsten’s (1997, 2000, 2004) idea of “shared substance” as the basis of kinship relations, I trace the idea of “shared discrimination” as one way in which tribal members have formed familial bonds even without being biologically related. I also examine the religious components of life in Poarch, including both Christianity and the traditional religious practice of stomp dancing. I describe the legal process of federal recognition and the Poarch Band of Creek’s petition for acknowledgement that was granted in 1983. I discuss the Wind Creek Casino and Hotel, a recently constructed Class II gaming facility on the Poarch Band of Creek Indian reservation, which supports the process of self-determination by the Poarch Band of Creek Indians. Finally, I discuss the ways in which tribal members are now able to express their pride in being a tribal member, as well as the ways that the tribe has contributed to the surrounding community.Ph.D.AnthropologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/89704/1/kfayard_1.pd

    Increasing Precision of Clinical Diagnosis of Alzheimer\u27s Disease Using a Combined Algorithm Incorporating Clinical and Novel Biomarker Data

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    Establishing the in vivo diagnosis of Alzheimer€ℱs disease (AD) or other dementias relies on clinical criteria; however, the accuracy of these criteria can be limited. The diagnostic accuracy is 77% for a clinical diagnosis of AD, even among experts. We performed a review through PubMed of articles related to specific diagnostic modalities, including APOE genotyping, cerebrospinal fluid (CSF) testing, fludeoxyglucose F 18 positron emission tomography (PET), amyloid PET, tau PET, computed tomography (CT), single-photon emission CT, magnetic resonance imaging (MRI), and B12 and thyroid-stimulating hormone screening, to determine the specificity and sensitivity of each test used in the clinical diagnosis of AD. We added a novel immunomagnetic reduction assay that provides ultrasensitivity for analyzing the levels of plasma tau and beta amyloid 42 (AÎÂČ42). The sensitivity and specificity of the current diagnostic approach (structural CT or MRI with screening labs) remain low for clinical detection of AD and are primarily used to exclude other conditions. Because of limited diagnostic capabilities, physicians do not feel comfortable or skilled in rendering a clinical diagnosis of AD. Compounding this problem is the fact that inexpensive, minimally invasive diagnostic tests do not yet exist. Biomarkers (obtained through CSF testing or PET imaging), which are not routinely incorporated in clinical practice, correlate well with pathologic changes. While PET is particularly costly and difficult to assess, CSF measures of tau and beta amyloid are not costly, and these tests may be worthwhile when the tiered approach proposed here warrants further testing. There is a need for developing bloodborne biomarkers that can aid in the clinical diagnosis of AD. Here we present a streamlined questionnaire-enriched, biomarker-enriched approach that is more cost-effective than the current diagnosis of exclusion and is designed to increase clinical confidence for a diagnosis of dementia due to AD

    Effects of Sound Symbolism in Names on Personality Perception

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    We investigated effects of sound symbolism in names on personality perception. Participants were randomly assigned to a group that either had invented or non-invented round or sharp names. They were asked to fill out a BFI-10 and a BSRI-12 questionnaire for five different names followed by reading 10 descriptions of personality traits and circling either a round name or a sharp name that fit the description best. Results showed that sound type present in names affected perceptions of Extraversion and that name and sound type affected perceptions of Femininity. These results provide evidence of sound symbolic associations present in names

    Return to sport and re-tears after anterior cruciate ligament reconstruction in children and adolescents

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    BACKGROUND: The primary objective of this study was to determine the time to and level of return to sports after anterior cruciate ligament (ACL) reconstruction in children and adolescents. The secondary objectives were to evaluate the risk of early ACL re-tear after return to sports and the risk of ACL tear in the contralateral knee. HYPOTHESIS: The time to return to sports in young patients is considerably longer than in adults. METHODS: A prospective multicentre study was conducted at 12 centres specialised in knee ligament surgery, in children and adolescents younger than 18 years, between 1 January 2015 and 31 October 2015. The patients were divided into a paediatric group with open physes and a skeletally mature group with closed physes. We recorded the time to return to sport, the type of sport resumed, and the occurrence of early re-tears on the same side. A poor outcome was defined as a re-tear or an objective IKDC score of C or D. A contralateral ACL tear was not considered a poor outcome. RESULTS: Of 278 included patients, 100 had open physes and 178 closed physes. In the open physes group, return to running occurred after 10.4±4.7 months, return to pivoting/contact sport training after 13.1±3.9 months, and return to pivoting/contact sport competitions after 13.8±3.8 months. Of the 100 patients, 80% returned to the same sport and 63.5% to pivoting/contact sport competitions. Re-tears occurred in 9% of patients, after 11.8±4.1 months, and contralateral tears in 6% of patients, after 17.2±4.4 months. In all, 19.4% of patients had a poor outcome, including 10.4% with an IKDC score of C or D and 9% with re-tears. In the group with closed physes, return to running occurred after 8.8±5.1 months, return to pivoting/contact sport training after 11.7±4.7 months, and return to pivoting/contact sport competitions after 12.3±4.2 months. Of the 178 patients, 76.9% returned to the same sport and 55.6% to pivoting/contact sport competitions. The re-tear rate was only 2.8% and the contralateral tear rate 5%. In all, 14.7% of patients had poor outcome, including 11.9% with an IKDC score of C or D and 2.8% with re-tears. No risk factors for re-tears were identified; the quadruple-bundle semitendinosus technique showed a non-significant association with re-tears. CONCLUSION: In young children, the return to sport time after ACL reconstruction is considerably longer than 1 year and the return to competitions occurs later and is more difficult. The results of this study indicate that reservations are in order when informing the family about return to sports prospects after ACL reconstruction. The return to pivoting/contact sport competitions should not be allowed until 14 months after surgery in young skeletally immature patients, and the risk of re-injury is high within the first 2 years. LEVEL OF EVIDENCE: IV, retrospective study

    Bodies, technologies and action possibilities: when is an affordance?

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    Borrowed from ecological psychology, the concept of affordances is often said to offer the social study of technology a means of re-framing the question of what is, and what is not, ‘social’ about technological artefacts. The concept, many argue, enables us to chart a safe course between the perils of technological determinism and social constructivism. This article questions the sociological adequacy of the concept as conventionally deployed. Drawing on ethnographic work on the ways technological artefacts engage, and are engaged by, disabled bodies, we propose that the ‘affordances’ of technological objects are not reducible to their material constitution but are inextricably bound up with specific, historically situated modes of engagement and ways of life

    Fermiophobic and other non-minimal neutral Higgs bosons at the LHC

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    The phenomenology of neutral Higgs bosons from non--SUSY, extended Higgs sectors is studied in the context of the LHC, with particular attention given to the case of a fermiophobic Higgs. It is found that enhanced branching ratios to γγ\gamma\gamma and τ+τ−\tau^+\tau^- are possible and can provide clear signatures, while detection of a fermiophobic Higgs will be problematic beyond a mass of 130 GeV.Comment: 16 pages, Latex, 5 figure

    Three-Body approach to the K^- d Scattering Length in Particle Basis

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    We report on the first calculation of the scattering length A_{K^-d} based on a relativistic three-body approach where the two-body input amplitudes coupled to the Kbar N channels have been obtained with the chiral SU(3) constraint, but with isospin symmetry breaking effects taken into account. Results are compared with a recent calculation applying a similar set of two-body amplitudes,based on the fixed center approximation, considered as a good approximation for a loosely bound target, and for which we find significant deviations from the exact three-body results. Effects of the hyperon-nucleon interaction, and deuteron DD-wave component are also evaluated.Comment: 5 pages, Submitted to Phys. Rev.
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