10,889 research outputs found
Evolution of dopant-induced helium nanoplasmas
Two-component nanoplasmas generated by strong-field ionization of doped
helium nanodroplets are studied in a pump-probe experiment using few-cycle
laser pulses in combination with molecular dynamics simulations. High yields of
helium ions and a pronounced, droplet size-dependent resonance structure in the
pump-probe transients reveal the evolution of the dopant-induced helium
nanoplasma. The pump-probe dynamics is interpreted in terms of strong inner
ionization by the pump pulse and resonant heating by the probe pulse which
controls the final charge states detected via the frustration of electron-ion
recombination
Care-seeking decisions for worsening symptoms in heart failure: a qualitative metasynthesis
Purpose: Over 50% of heart failure (HF) patients delay seeking help for worsening symptoms until these reach acute levels and require emergency hospitalisation. This metasynthesis aimed to identify and explore factors influencing timely care-seeking in patients with HF. Methods: Electronic databases searched were Medline, EMBASE and CINAHL. Studies were included if they were peer reviewed journal articles written in English, and reported perspectives of HF patients following qualitative data collection and analysis. Forty articles underwent analysis following the approach of Thomas and Harden. Leventhal's self-regulatory model (SRM) was used to organise the literature. Results: Much of the literature fit within the SRM, however this model did not account for all factors that influence patients’ care-seeking for worsening symptoms. Factors not accounted for included patients’ appraisals of previous care-seeking experiences, perceived system and provider barriers to accessing care, and the influence of external appraisals. When added to factors already represented in the model, such as misattribution of symptoms, not identifying with HF diagnosis, cognitive status, lack of understanding information provided, adaptation to symptoms, and emotional responses, a more comprehensive account of patients’ decision-making was revealed. Implications: This metasynthesis identified factors, as yet unaccounted for, in a prominent model, and has suggested a more comprehensive framework for addressing care-seeking in HF patients. This information can be used to tailor education, communication, and service initiatives to improve HF patients’ responses to worsening symptoms
Multi-view Vehicle Detection based on Part Model with Active Learning
© 2018 IEEE. Nowadays, most ofthe vehicle detection methods aim to detect only single-view vehicles, and the performance is easily affected by partial occlusion. Therefore, a novel multi-view vehicle detection system is proposed to solve the problem of partial occlusion. The proposed system is divided into two steps: Background filtering and part model. Background filtering step is used to filter out trees, sky and other road background objects. In the part model step, each of the part models is trained by samples collected by using the proposed active learning algorithm. This paper validates the performance of the background filtering method and the part model algorithm in multi-view car detection. The performance of the proposed method outperforms previously proposed methods
Controlling laser spectra in a phaseonium photonic crystal using maser
We study the control of quantum resonances in photonic crystals with
electromagnetically induced transparency driven by microwave field. In addition
to the control laser, the intensity and phase of the maser can alter the
transmission and reflection spectra in interesting ways, producing hyperfine
resonances through the combined effects of multiple scattering in the
superstructure.Comment: 7 pages, 4 figure
Fine Selmer Groups and Isogeny Invariance
We investigate fine Selmer groups for elliptic curves and for Galois
representations over a number field. More specifically, we discuss Conjecture
A, which states that the fine Selmer group of an elliptic curve over the
cyclotomic extension is a finitely generated -module. The
relationship between this conjecture and Iwasawa's classical conjecture
is clarified. We also present some partial results towards the question whether
Conjecture A is invariant under isogenies.Comment: 20 page
Extraordinary Late-Time Infrared Emission of Type IIn Supernovae
Near-Infrared (NIR) observations are presented for five Type IIn supernovae
(SN 1995N, SN 1997ab, SN 1998S, SN 1999Z, and SN 1999el) that exhibit strong
infrared excesses at late times (t >= 100 d). H- and K-band emission from these
objects is dominated by a continuum that rises toward longer wavelengths. The
data are interpreted as thermal emission from dust, probably situated in a
pre-existing circumstellar nebula. The IR luminosities implied by single
temperature blackbody fits are quite large,> 10^(41 - 42) erg s^-1, and the
emission evolves slowly, lasting for years after maximum light. For SN 1995N,
the integrated energy release via IR dust emission was 0.5 -- 1 * 10^50 erg. A
number of dust heating scenarios are considered, the most likely being an
infrared echo poweredby X-ray and UV emissions from the shock interaction with
a dense circumstellar medium.Comment: 14 Pages, 3 Figures, Accecpted for publication in The Astrophysical
Journa
Role of Keystone Species in Aquatic Ecosystem
A keystone species is a species that has a disproportionately large effect on its environment relative to its abundance. Such species play a critical role in maintaining the structure of an ecological community, affecting many other organism s in an ecosystem and helping to determine the types and numbers of various other species
in the community
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