145 research outputs found

    The X-ray properties of the magnetic cataclysmic variable UUColumbae

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    Aims. XMM-Newton observations to determine for the first time the broad-band X-ray properties of the faint, high galactic latitude intermediate polar UUCol are presented. Methods. We performed X-ray timing analysis in different energy ranges of the EPIC cameras, which reveals the dominance of the 863 s white dwarf rotational period. The spin pulse is strongly energy dependent. Weak variabilities at the beat 935 s and at the 3.5 h orbital periods are also observed, but the orbital modulation is detected only below 0.5 keV. Simultaneous UV and optical photometry shows that the spin pulse is anti-phased with respect to the hard X-rays. Analysis of the EPIC and RGS spectra reveals the complexity of the X-ray emission, which is composed of a soft 50 eV black–body component and two optically thin emission components at 0.2 keV and 11 keV strongly absorbed by dense material with an equivalent hydrogen column density of 1023 cm−2 that partially (50%) covers the X-ray source. Results. The complex X-ray and UV/optical temporal behaviour indicates that accretion occurs predominantly (∼80%) via a disc with a partial contribution (∼20%) directly from the stream. The main accreting pole dominates at high energies whilst the secondary pole mainly contributes in the soft X-rays and at lower energies. The bolometric flux ratio of the soft-to-hard X-ray emissions is found to be consistent with the prediction of the standard accretion shock model. We find the white dwarf in UUCol accretes at a low rate and possesses a low magnetic moment. It is therefore unlikely that UUCol will evolve into a moderate field strength polar, so that the soft X-ray intermediate polars still remain an enigmatic small group of magnetic cataclysmic variables

    Towards Investigating Global Warming Impact on Human Health Using Derivatives of Photoplethysmogram Signals

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    Recent clinical studies show that the contour of the photoplethysmogram (PPG) wave contains valuable information for characterizing cardiovascular activity. However, analyzing the PPG wave contour is difficult; therefore, researchers have applied first or higher order derivatives to emphasize and conveniently quantify subtle changes in the filtered PPG contour. Our hypothesis is that analyzing the whole PPG recording rather than each PPG wave contour or on a beat-by-beat basis can detect heat-stressed subjects and that, consequently, we will be able to investigate the impact of global warming on human health. Here, we explore the most suitable derivative order for heat stress assessment based on the energy and entropy of the whole PPG recording. The results of our study indicate that the use of the entropy of the seventh derivative of the filtered PPG signal shows promising results in detecting heat stress using 20-second recordings, with an overall accuracy of 71.6%. Moreover, the combination of the entropy of the seventh derivative of the filtered PPG signal with the root mean square of successive differences, or RMSSD (a traditional heart rate variability index of heat stress), improved the detection of heat stress to 88.9% accuracy

    BeppoSAX observations of soft X-ray Intermediate Polars

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    We present broad-band (0.1--90keV) spectral and temporal properties of the three Intermediate Polars, RE0751+144 (PQ Gem), RXJ0558.0+5353 (V405Aur) and RXJ1712.6-2414 (V2400 Oph) based on simultaneous soft and hard X-ray observations with the BeppoSAX satellite. The analysis of their spectra over the wide energy range of BeppoSAX instruments allows us to identify the soft and hard X-ray components and to determine simultaneously their temperatures. The black--body temperatures of the irradiated poles of the white dwarf atmosphere are found to be 60--100eV, much higher than those found in their synchronous analogues, the Polars. The temperature of the optically thin post--shock plasma is well constrained in RXJ1712.6-2414 and in RE0751+144 (13 and 17keV) and less precisely determined in RXJ0558.0+5353. In the first two systems evidence of subsolar abundances is found, similarly to what estimated in other magnetic Cataclysmic Variables. A Compton reflection component is present in RXJ0558.0+5353 and in RE0751+144 and it is favoured in RXJ1712.6-2414. Its origin is likely at the irradiated white dwarf surface. Although these systems share common properties (soft X-ray component and optical polarized radiation), their X-ray power spectra and light curves at different energies suggest accretion geometries which cannot be reconciled with a single and simple configuration.Comment: 12 pages, 15 postscript figures, LateX, uses aa.cls. Accepted for publications in Astronomy and Astrophysics Main Journa

    No Pain No Gain: Standards mapping in Latimer Core development

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    Latimer Core (LtC) is a new proposed Biodiversity Information Standards (TDWG) data standard that supports the representation and discovery of natural science collections by structuring data about the groups of objects that those collections and their subcomponents encompass (Woodburn et al. 2022). It is designed to be applicable to a range of use cases that include high level collection registries, rich textual narratives and semantic networks of collections, as well as more granular, quantitative breakdowns of collections to aid collection discovery and digitisation planning.As a standard that is (in this first version) focused on natural science collections, LtC has significant intersections with existing data standards and models (Fig. 1) that represent individual natural science objects and occurrences and their associated data (e.g., Darwin Core (DwC), Access to Biological Collection Data (ABCD), Conceptual Reference Model of the International Committee on Documentation (CIDOC-CRM)). LtC's scope also overlaps with standards for more generic concepts like metadata, organisations, people and activities (i.e., Dublin Core, World Wide Web Consortium (W3C) ORG Ontology and PROV Ontology, Schema.org). LtC represents just an element of this extended network of data standards for the natural sciences and related concepts. Mapping between LtC and intersecting standards is therefore crucial for avoiding duplication of effort in the standard development process, and ensuring that data stored using the different standards are as interoperable as possible in alignment with FAIR (Findable, Accessible, Interoperable, Reusable) principles. In particular, it is vital to make robust associations between records representing groups of objects in LtC and records (where available) that represent the objects within those groups.During LtC development, efforts were made to identify and align with relevant standards and vocabularies, and adopt existing terms from them where possible. During expert review, a more structured approach was proposed and implemented using the Simple Knowledge Organization System (SKOS) mappingRelation vocabulary. This exercise helped to better describe the nature of the mappings between new LtC terms and related terms in other standards, and to validate decisions around the borrowing of existing terms for LtC. A further exercise also used elements of the Simple Standard for Sharing Ontological Mappings (SSSOM) to start to develop a more comprehensive set of metadata around these mappings. At present, these mappings (Suppl. material 1 and Suppl. material 2) are provisional and not considered to be comprehensive, but should be further refined and expanded over time.Even with the support provided by the SKOS and SSSOM standards, the LtC experience has proven the mapping process to be far from straightforward. Different standards vary in how they are structured, for example, DwC is a 'bag of terms', with informal classes and no structural constraints, while more structured standards and ontologies like ABCD and PROV employ different approaches to how structure is defined and documented. The various standards use different metadata schemas and serialisations (e.g., Resource Description Framework (RDF), XML) for their documentation, and different approaches to providing persistent, resolvable identifiers for their terms. There are also many subtle nuances involved in assessing the alignment between the concepts that the source and target terms represent, particularly when assessing whether a match is exact enough to allow the existing term to be adopted. These factors make the mapping process quite manual and labour-intensive. Approaches and tools, such as developing decision trees (Fig. 2) to represent the logic involved and further exploration of the SSSOM standard, could help to streamline this process.In this presentation, we will discuss the LtC experience of the standard mapping process, the challenges faced and methods used, and the potential to contribute this experience to a collaborative standards mapping within the anticipated TDWG Standards Mapping Interest Group

    X-ray confirmation of the intermediate polar HTCam

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    We report on the first pointed X-ray observations with XMM-Newton and RXTE satellites of the X-ray source RXJ0757.0+6306 = HT Cam. We detect a strong 515 s X-ray modulation confirming the optical photometric period found in 1998, which definitively assigns this source to the intermediate polar class of magnetic cataclysmic variables. The lack of orbital sidebands in the X-rays indicates that the X-ray period is the spin period of the accreting white dwarf. Simultaneous ultraviolet and optical B-band photometry acquired with the XMM-Newton Optical Monitor and coordinated optical UBVRI photometric data acquired at the Nordic Optical Telescope (La Palma) show that the optical pulse is in phase with the X-rays and hence originates in the magnetically-confined accretion flow. The lack of ultraviolet spin modulation suggests that accretion-induced heating on the white dwarf surface is not important in this source. Spectral analyses of XMM-Newton EPIC and RGS data show that HTCam has a multi-temperature spectrum and, contrary to most intermediate polars, it does not suffer from strong absorption. With its 86 min orbital period, HTCam is the third confirmed system of this class below the 2–3 h period gap accreting at a low rate

    A faculty–librarian collaboration successsStory: Implementing a teach-the-teacher library and information literacy instruction model in a first-year agricultural science course

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    Teaching information literacy requires a constant and evolving paradigm shift in today's fast-changing technology era. Add to this the intricacy of agricultural science education, and it becomes clear that instructors face challenges teaching the necessary research skills to prepare the next generation of scientists. Two faculty members in Colorado State University's College of Agricultural Sciences identified a need to redesign a core agricultural science course after observing their students struggle with research and writing. These professors improved their course through a redesign program that connected them with librarians. This collaboration led to the creation of a scaffold to help students build information literacy skills through a first-year agricultural science course. In this paper the authors discuss this collaboration, including four key factors to the program's success: a) a faculty–librarian partnership through a learning and teaching institute; b) early exposure to information literacy skills in a first-year agricultural science course; c) the integration of a research guide in a Learning Management System (LMS), and a step-by-step library and information literacy instruction session with a library assignment; and d) a teach-the-teacher model using graduate students from the respective discipline. The authors also analyze student evaluation outcomes and reflect on future improvements

    Rescuing the Mortgage Giants

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    Paper addresses the 2008 rescues of Fannie Mae and Freddie Mac, the two government-sponsored enterprises focussed on the mortgage market. Part of a series of XX papers -RESPONDING to the GLOBAL FINANCIAL CRISIS: What We Did and Why We Did It, presented on September 11-12, 2018, at the Hutchins Center of the Brookings Institute and co-sponsored by the Yale Program on Financial Stability, in light of the 10th Anniversary of the Global Financial Crisis

    Ubu Roi

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    Program for the nineth annual RISD Cabaret held in the Waterman Building commemorating the 100th anniversary of the premier of Alfred Jarry\u27s 1896 play, Ubu Roi . Graphic design: Matt DeSmith and Vivian Law.https://digitalcommons.risd.edu/liberalarts_cabaret_programs/1008/thumbnail.jp

    Systolic peak detection in acceleration photoplethysmograms measured from emergency responders in tropical conditions

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    Abstract Photoplethysmogram (PPG) monitoring is not only essential for critically ill patients in hospitals or at home, but also for those undergoing exercise testing. However, processing PPG signals measured after exercise is challenging, especially if the environment is hot and humid. In this paper, we propose a novel algorithm that can detect systolic peaks under challenging conditions, as in the case of emergency responders in tropical conditions. Accurate systolic-peak detection is an important first step for the analysis of heart rate variability. Algorithms based on local maxima-minima, first-derivative, and slope sum are evaluated, and a new algorithm is introduced to improve the detection rate. With 40 healthy subjects, the new algorithm demonstrates the highest overall detection accuracy (99.84% sensitivity, 99.89% positive predictivity). Existing algorithms, such as Billauer's, Li's and Zong's, have comparable although lower accuracy. However, the proposed algorithm presents an advantage for real-time applications by avoiding human intervention in threshold determination. For best performance, we show that a combination of two event-related moving averages with an offset threshold has an advantage in detecting systolic peaks, even in heat-stressed PPG signals

    RACE-OC Project: Rotation and variability in the epsilon Chamaeleontis, Octans, and Argus stellar associations

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    We aim at determining the rotational and magnetic-related activity properties of stars at different stages of evolution. We focus our attention primarily on members of young stellar associations of known ages. Specifically, we extend our previous analysis in Paper I (Messina et al. 2010, A&A 520, A15) to 3 additional young stellar associations beyond 100 pc and with ages in the range 6-40 Myr: epsilon Chamaeleontis (~6 Myr), Octans (~20 Myr), and Argus (~40 Myr). Additional rotational data of eta Chamaeleontis and IC2391 clusters are also considered. Rotational periods were determined from photometric time-series data obtained by the All Sky Automated Survey (ASAS) and the Wide Angle Search for Planets (SuperWASP) archives. With the present study we have completed the analysis of the rotational properties of the late-type members of all known young loose associations in the solar neighborhood. Considering also the results of Paper I, we have derived the rotation periods of 241 targets: 171 confirmed, 44 likely, 26 uncertain. The period of the remaining 50 stars known to be part of loose associations still remains unknown. This rotation period catalogue, and specifically the new information presented in this paper at ~6, 20, and 40 Myr, contributes significantly to a better observational description of the angular momentum evolution of young stars.Comment: Accepted by Astronomy & Astrophysics. Onlines figures will be available at CD
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