6,900 research outputs found

    Quantum estimation of a damping constant

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    We discuss an interferometric approach to the estimation of quantum mechanical damping. We study specific classes of entangled and separable probe states consisting of superpositions of coherent states. Based on the assumption of limited quantum resources we show that entanglement improves the estimation of an unknown damping constant.Comment: 7 pages, 5 figure

    First Structure Formation: A Simulation of Small Scale Structure at High Redshift

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    We describe the results of a simulation of collisionless cold dark matter in a LambdaCDM universe to examine the properties of objects collapsing at high redshift (z=10). We analyze the halos that form at these early times in this simulation and find that the results are similar to those of simulations of large scale structure formation at low redshift. In particular, we consider halo properties such as the mass function, density profile, halo shape, spin parameter, and angular momentum alignment with the minor axis. By understanding the properties of small scale structure formation at high redshift, we can better understand the nature of the first structures in the universe, such as Population III stars.Comment: 31 pages, 14 figures; accepted for publication in ApJ. Figure 1 can also be viewed at http://cfa-www.harvard.edu/~hjang/research

    Ecosystem Food Web Lift-the-Flap Pages

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    In the lesson on which this practical article is based, third grade students constructed a ā€œlift-the-flapā€ page to explore food webs on the prairie. The moveable papercraft focused student attention on prairie animalsā€™ external structures and how the inferred functions of those structures could support further inferences about the animalsā€™ diets. In general, most students made simple causal connections between an animalā€™s observable characteristics and the food it would probably eat. Some students were also able to make multi-agent connections to develop a more complex mental model of a food web. Ultimately, the lift-the flap project was engaging to students and motivated them to focus their attention on the characteristics of animals of different ecosystems to infer their probable diets

    Predicting suitable environments and potential occurrences for coelacanths (Latimeria spp.)

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    This is the author's accepted manuscript. The original publication is available at www.springerlink.com.Extant coelacanths (Latimeria chalumnae) were first discovered in the western Indian Ocean in 1938; in 1998, a second species of coelacanth, Latimeria menadoensis, was discovered off the north coast of Sulawesi, Indonesia, expanding the known distribution of the genus across the Indian Ocean Basin. This study uses ecological niche modeling techniques to estimate dimensions of realized niches of coelacanths and generate hypotheses for additional sites where they might be found. Coelacanth occurrence information was integrated with environmental and oceanographic data using the Genetic Algorithm for Rule-set Production (GARP) and a maximum entropy algorithm (Maxent). Resulting models were visualized as maps of relative suitability of sites for coelacanths throughout the Indian Ocean, as well as scatterplots of ecological variables. Our findings suggest that the range of coelacanths could extend beyond their presently known distribution and suggests alternative mechanisms for currently observed distributions. Further investigation into these hypotheses could aid in forming a more complete picture of the distributions and populations of members of genus Latimeria, which in turn could aid in developing conservation strategies, particularly in the case of L. menadoensis

    Droplet digital PCR for oncogenic KMT2A fusion detection

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    Acute myeloid leukemia (AML) is an aggressive blood cancer diagnosed in approximately 120,000 individuals worldwide each year. During treatment for AML, detecting residual disease is essential for prognostication and treatment decision-making. Currently, methods for detecting residual AML are limited to identifying approximately 1:100 to 1:1000 leukemic cells (morphology and DNA sequencing) or are difficult to implement (flow cytometry). AML arising after chemotherapy or radiation exposure is termed therapy-related AML (t-AML) and is exceptionally aggressive and treatment resistant. t-AML is often driven by oncogenic fusions that result from prior treatments that introduce double-strand DNA breaks. The most common t-AML-associated translocations affect KMT2A. There are at least 80 known KMT2A fusion partners, but approximately 80% of fusions involve only five partners-AF9, AF6, AF4, ELL, and ENL. We present a novel droplet digital PCR assay targeting the most common KMT2A-rearrangements to enable detection of rare AML cells harboring these fusions. This assay was benchmarked in cell lines and patient samples harboring oncogenic KMT2A fusions and demonstrated a limit of detection of approximately 1:1,000,000 cells. Future application of this assay could improve disease detection and treatment decision-making for patients with t-AML with KMT2A fusions and premalignant oncogenic fusion detection in at-risk individuals after chemotherapy exposure

    Evaluation of the Audicor Acoustic Cardiography Device as a Diagnostic Tool in Horses with Mitral or Aortic Valve Insufficiency

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    Mitral and aortic valve insufficiencies have been commonly reported in horses. The objective of this study was to establish the use of acoustic cardiography (AudicorĀ®) in horses with aortic (AI) or mitral valve insufficiency (MI). A total of 17 healthy horses, 18 horses with AI, and 28 horses with MI were prospectively included. None of the horses was in heart failure. Echocardiography and AudicorĀ® analyses were conducted. Electromechanical activating time (EMAT), rate-corrected EMATc, left ventricular systolic time (LVST), rate-corrected LVSTc, and intensity and persistence of the third and fourth heart sound (S3, S4) were reported by AudicorĀ®. Graphical analysis of the three-dimensional (3D) phonocardiogram served to visually detect murmurs. AudicorĀ® snapshot variables were compared between groups using one-way ANOVA followed by Tukeyā€™s multiple-comparisons test. The association between AudicorĀ® snapshot variables and the corresponding echocardiographic variables was investigated by linear regression and Blandā€“Altman analyses. Heart murmurs were not displayed on AudicorĀ® phonocardiograms. No significant differences were found between AudicorĀ® variables obtained in clinically healthy horses and horses with valvular insufficiency. The AudicorĀ® device is unable to detect heart murmurs in horses. AudicorĀ® variables representing cardiac function are not markedly altered, and their association with corresponding echocardiographic variables is poor in horses with valvular insufficiency that are not in heart failure

    Alarmins in frozen shoulder: a molecular association between inflammation and pain

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    Background: The pathophysiological mechanisms behind proliferation of fibroblasts and deposition of dense collagen matrix in idiopathic frozen shoulder remain unclear. Alarmins (also known as danger signals) are endogenous molecules that are released into the extracellular milieu after infection or tissue injury and that signal cell and tissue damage. Purpose: To investigate whether the presence of alarmins is higher in patients with idiopathic frozen shoulder than in control subjects. Study Design: Controlled laboratory study. Methods: Shoulder capsule samples were collected from 10 patients with idiopathic frozen shoulder and 10 patients with unstable shoulders (control). The samples were stained with hematoxylin and eosin (H&E) and analyzed by immunohistochemistry using antibodies against alarmin molecules including high-mobility group protein B1 (HMGB1), interleukin 33, S100A8, S100A9, and the peripheral nerve marker PGP9.5. Immunoreactivities were rated in a blinded fashion from ā€œnoneā€ to ā€œstrong.ā€ Immunohistochemical distribution within the capsule was noted. Before surgery, patient-ranked pain frequency, severity, stiffness, and the range of passive shoulder motion were recorded and statistically analyzed. Results: Compared with control patients, patients with frozen shoulder had greater frequency and severity of self-reported pain (P = .02) and more restricted range of motion in all planes (P < .05). H&E-stained capsular tissue from frozen shoulder showed fibroblastic hypercellularity and increased subsynovial vascularity. Immunoreactivity of alarmins was significantly stronger in frozen shoulder capsules compared with control capsules (P < .05). Furthermore, the expression of the alarmin molecule HMGB1 significantly correlated (r > 0.9, P < .05) with the severity of patient-reported pain. Conclusion: This study demonstrates a potential role for key molecular danger signals in frozen shoulder and suggests an association between the expression of danger molecules and the pain experienced by patients

    A model suite of green algae within the Scenedesmaceae for investigating contrasting desiccation tolerance and morphology

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    Author Posting. Ā© The Company of Biologists, 2018. This article is posted here by permission of The Company of Biologists for personal use, not for redistribution. The definitive version was published in Journal of Cell Science 131 (2018): jcs212233, doi:10.1242/jcs.212233.Microscopic green algae inhabiting desert microbiotic crusts are remarkably diverse phylogenetically, and many desert lineages have independently evolved from aquatic ancestors. Here we worked with five desert and aquatic species within the family Scenedesmaceae to examine mechanisms that underlie desiccation tolerance and release of unicellular versus multicellular progeny. Live cell staining and time-lapse confocal imaging coupled with transmission electron microscopy established that the desert and aquatic species all divide by multiple (rather than binary) fission, although progeny were unicellular in three species and multicellular (joined in a sheet-like coenobium) in two. During division, Golgi complexes were localized near nuclei, and all species exhibited dynamic rotation of the daughter cell mass within the mother cell wall at cytokinesis. Differential desiccation tolerance across the five species, assessed from photosynthetic efficiency during desiccation/rehydration cycles, was accompanied by differential accumulation of intracellular reactive oxygen species (ROS) detected using a dye sensitive to intracellular ROS. Further comparative investigation will aim to understand the genetic, ultrastructural and physiological characteristics supporting unicellular versus multicellular coenobial morphology, and the ability of representatives in the Scenedesmaceae to colonize ecologically diverse, even extreme, habitats.This work was supported by the National Science Foundation, Division of Integrative Organismal Systems [1355085 to Z.G.C.], an anonymous donor [to Z.G.C.], the Marine Biological Laboratory [to M.B.] and the Environmental and Molecular Sciences Laboratory (EMSL) [48938 to Z.G.C.], a Department of Energy, Office of Science User Facility sponsored by the Office of Biological and Environmental Research, located at Pacific Northwest National Laboratory.2019-04-1
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