3,108 research outputs found
Analytical expressions for optimum alignment modes of highly segmented mirrors
The major sources causing deterioration of optical quality in extremely large
optical telescopes are misadjustments of the mirrors, deformations of
monolithic mirrors, and misalignments of segments in segmented mirrors. For
active optics corrections, all three errors, which can partially compensate
each other, are measured simultaneously. It is therefore of interest to
understand the similarities and differences between the three corresponding
types of modes which describe these errors. The first two types are best
represented by Zernike polynomials and elastic modes respectively, both of them
being continuous and smooth functions. The segment misaligment modes, which are
derived by singular value decomposition, are by their nature not smooth and in
general discontinuous. However, for mirrors with a large number of segments,
the lowest modes become effectively both smooth and continuous. This paper
derives analytical expressions for these modes, using differential operators
and their adjoints, for the limit case of infinitesimally small segments. For
segmented mirrors with approximately 1000 segments, it is shown that these
modes agree well with the corresponding lowest singular value decomposition
modes. Furthermore, the analytical expressions reveal the nature of the segment
misalignment modes and allow for a detailed comparison with the elastic modes
of monolithic mirrors. Some mathematical features emerge as identical in the
two cases.Comment: 24 pages, 13 figures, accepted for publication in Journal of Modern
Optic
A Note On Fixed-point Theorems
In an earlier note, S. P. Singh gave an extension of a theorem of Brosowski in a normed linear space setting. Variants of this theorem are considered in the context of strictly convex, reflexive, and inner product spaces. © 1982
Ritualized Display of a Leaf: A Putative Agonistic Signal in Both Sexes of Tropical Bird
Birds use many different signaling modalities (e.g. vocalizations, displays) to transmit information about their motivation to defend valuable resources. A handful of taxa use props , inedible objects scavenged from the environment, in signaling. Several species of motmots (Coraciiformes) hold a leaf in their bill in a display that observational evidence suggests is agonistic. We used a simulated intruder experiment to test this display\u27s agonistic signaling function using data from both members of pairs of russet-crowned motmots (Momotus mexicanus). If the display is agonistic, we expected territory-holding pairs to respond more strongly toward taxidermic mounts displaying a leaf. Our results showed that resident pairs reacted differently to the leaf display depending on the intruder\u27s sex. Display of a leaf by the intruder increased the closeness of the pairs\u27 approach when the model was male, but increased the probability of the territorial defenders displaying a leaf themselves when the model was female. Pairs spent more time responding to male models regardless of leaf display. Our results suggest that the leaf display is an agonistic signal, that territory owners react differently to the leaf display depending on the sex of the intruder performing it, and that the participation of both sexes in territorial defense-which is common among tropical resident birds-extends to this unusual signaling modality
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The peripheral blood transcriptome in septic cardiomyopathy: an observational, pilot study.
BACKGROUND:Septic cardiomyopathy (SCM) is common in sepsis and associated with increased morbidity and mortality. Left ventricular global longitudinal strain (LV GLS), measured by speckle tracking echocardiography, allows improved identification of impaired cardiac contractility. The peripheral blood transcriptome may be an important window into SCM pathophysiology. We therefore studied the peripheral blood transcriptome and LV GLS in a prospective cohort of patients with sepsis. RESULTS:In this single-center observational pilot study, we enrolled adult patients (age > 18) with sepsis within 48 h of admission to the ICU. SCM was defined as LV GLS > - 17% based on echocardiograms performed within 72 h of admission. We enrolled 27 patients, 24 of whom had high-quality RNA results; 18 (75%) of 24 had SCM. The group was 50% female and had a median (IQR) age of 59.5 (48.5-67.0) years and admission APACHE II score of 21.0 (16.0-32.3). Forty-six percent had septic shock. After filtering for low-expression and non-coding genes, 15,418 protein coding genes were expressed and 73 had significantly different expression between patients with vs. without SCM. In patients with SCM, 43 genes were upregulated and 30 were downregulated. Pathway analysis identified enrichment in type 1 interferon signaling (adjusted p < 10-5). CONCLUSIONS:In this hypothesis-generating study, SCM was associated with upregulation of genes in the type 1 interferon signaling pathway. Interferons are cytokines that stimulate the innate and adaptive immune response and are implicated in the early proinflammatory and delayed immunosuppression phases of sepsis. While type 1 interferons have not been implicated previously in SCM, interferon therapy (for viral hepatitis and Kaposi sarcoma) has been associated with reversible cardiomyopathy, perhaps suggesting a role for interferon signaling in SCM
Singular and regular solutions of a non-linear parabolic system
We study a dissipative nonlinear equation modelling certain features of the
Navier-Stokes equations. We prove that the evolution of radially symmetric
compactly supported initial data does not lead to singularities in dimensions
. For dimensions we present strong numerical evidence supporting
existence of blow-up solutions. Moreover, using the same techniques we
numerically confirm a conjecture of Lepin regarding existence of self-similar
singular solutions to a semi-linear heat equation.Comment: 16 page
Study protocol for the Anesthesiology Control Tower—Feedback Alerts to Supplement Treatments (ACTFAST-3) trial: A pilot randomized controlled trial in intraoperative telemedicine [version 1; referees: 2 approved]
Background: Each year, over 300 million people undergo surgical procedures worldwide. Despite efforts to improve outcomes, postoperative morbidity and mortality are common. Many patients experience complications as a result of either medical error or failure to adhere to established clinical practice guidelines. This protocol describes a clinical trial comparing a telemedicine-based decision support system, the Anesthesiology Control Tower (ACT), with enhanced standard intraoperative care. Methods: This study is a pragmatic, comparative effectiveness trial that will randomize approximately 12,000 adult surgical patients on an operating room (OR) level to a control or to an intervention group. All OR clinicians will have access to decision support software within the OR as a part of enhanced standard intraoperative care. The ACT will monitor patients in both groups and will provide additional support to the clinicians assigned to intervention ORs. Primary outcomes include blood glucose management and temperature management. Secondary outcomes will include surrogate, clinical, and economic outcomes, such as incidence of intraoperative hypotension, postoperative respiratory compromise, acute kidney injury, delirium, and volatile anesthetic utilization. Ethics and dissemination: The ACTFAST-3 study has been approved by the Human Resource Protection Office (HRPO) at Washington University in St. Louis and is registered at clinicaltrials.gov (NCT02830126). Recruitment for this protocol began in April 2017 and will end in December 2018. Dissemination of the findings of this study will occur via presentations at academic conferences, journal publications, and educational materials
The Bright Side of Hematopoiesis: Regulatory Roles of ARID3a/Bright in Human and Mouse Hematopoiesis
ARID3a/Bright is a DNA-binding protein that was originally discovered for its ability to increase immunoglobulin transcription in antigen-activated B cells. It interacts with DNA as a dimer through its ARID, or A/T-rich interacting domain. In association with other proteins, ARID3a increased transcription of the immunoglobulin heavy chain and led to improved chromatin accessibility of the heavy chain enhancer. Constitutive expression of ARID3a in B lineage cells resulted in autoantibody production, suggesting its regulation is important. Abnormal ARID3a expression has also been associated with increased proliferative capacity and malignancy. Roles for ARID3a in addition to interactions with the immunoglobulin locus were suggested by transgenic and knockout mouse models. Over-expression of ARID3a resulted in skewing of mature B cell subsets and altered gene expression patterns of follicular B cells, whereas loss of function resulted in loss of B1 lineage B cells and defects in hematopoiesis. More recent studies showed that loss of ARID3a in adult somatic cells promoted developmental plasticity, alterations in gene expression patterns, and lineage fate decisions. Together, these data suggest new regulatory roles for ARID3a. The genes influenced by ARID3a are likely to play pivotal roles in lineage decisions, highlighting the importance of this understudied transcription factor
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