4,118 research outputs found

    Infusing Problem-Based Learning (PBL) Into Science Methods Courses Across Virginia

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    This article outlines the results of a collaborative study of the effects of infusing problem-based learning (PBL) into K-12 science methods courses across four universities in Virginia. Changes in pre-service teachers\u27 attitudes surrounding science teaching were measured before and after completing a science methods course in which they experienced PBL first-hand as participants, and then practiced designing their own PBL units for use in their future classrooms. The results indicate that exposure to PBL enhances pre-service teachers\u27 knowledge of inquiry methods and self-efficacy in teaching science

    Using the <i>aa</i> index over the last 14 solar cycles to characterize extreme geomagnetic activity

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    Geomagnetic indices are routinely used to characterize space weather event intensity. The DST index is well resolved, but is only available over 5 solar cycles. The aa index extends over 14 cycles but is highly discretized with poorly resolved extremes. We parameterize extreme aa activity by the annual averaged top few % of observed values, show these are exponentially distributed and they track annual DST index minima. This gives a 14 cycle average of ~ 4% chance of at least one great (DST nT) storm and ~ 28% chance of at least one severe (DST nT) storm per year. At least one DST=‐809 [‐663,‐955] nT event in a given year would be a 1:151 year event. Carrington event estimate DST ~ ‐850 nT is within the same distribution as other extreme activity seen in aa since 1868 so that its likelihood can be deduced from that of more moderate events. Events with DST â‰Č ‐1000 nT are in a distinct class, requiring special conditions

    A Radial Velocity Study of CTCV J1300-3052

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    We present time-resolved spectroscopy of the eclipsing, short period cataclysmic variable CTCV J1300-3052. Using absorption features from the secondary star, we determine the radial velocity semi-amplitude of the secondary star to be K2 = 378 \pm 6 km/s, and its projected rotational velocity to be v sin i = 125 \pm 7 km/s. Using these parameters and Monte Carlo techniques, we obtain masses of M1 = 0.79 \pm 0.05 MSun for the white dwarf primary and M2 = 0.198 \pm 0.029 MSun for the M-type secondary star. These parameters are found to be in excellent agreement with previous mass determinations found via photometric fitting techniques, supporting the accuracy and validity of photometric mass determinations in short period CVs.Comment: Accepted for publication in MNRAS (24th January 2012). 10 pages, 9 figures (black and white

    Perturbations in the Kerr-Newman Dilatonic Black Hole Background: Maxwell Waves, the Dilaton Background and Gravitational Lensing

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    In this paper we continue the analysis of our previous papers and study the affect of the existence of a non-trivial dilaton background on the propagation of electromagnetic waves in the Kerr-Newman dilatonic black hole space-time. For this purpose we again employ the double expansion in both the background electric charge and the wave parameters of the relevant quantities in the Newman-Penrose formalism and then identify the first order at which the dilaton background enters the Maxwell equations. We then assume that gravitational and dilatonic waves are negligible (at that order in the charge parameter) with respect to electromagnetic waves and argue that this condition is consistent with the solutions already found in the previous paper. Explicit expressions are given for the asymptotic behavior of scattered waves, and a simple physical model is proposed in order to test the effects. An expression for the relative intensity is obtained for Reissner-Nordstrom dilaton black holes using geometrical optics. A comparison with the approximation of geometrical optics for Kerr-Newman dilaton black holes shows that at the order to which the calculations are carried out gravitational lensing of optical images cannot probe the dilaton background.Comment: 9 pages, 1 figur

    HST/STIS UV Spectroscopy of Two Quiescent X-ray Novae: A0620-00 and Centaurus X-4

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    In 1998 we made UV spectroscopic observations with HST/STIS of A0620-00 and Cen X-4, which are two X-ray novae (aka soft X-ray transients). These binary systems are similar in all respects except that the former contains a black hole and the latter contains a neutron star. A UV spectrum (1700-3100A) is presented for the quiescent state of each system in the context of previously published UV/optical and X-ray data. The non-stellar, continuum spectrum of black hole A0620-00 has a prominent UV/optical peak centered at about 3500A. In contrast the spectrum of neutron-star Cen X-4 lacks a peak and rises steadily with frequency over the entire UV/optical band. In the optical, the two systems are comparably luminous. However, black hole A0620-00 is about 6 times less luminous at 1700A, and about 40 times less luminous in the X-ray band. The broadband spectrum of A0620-00 is discussed in terms of the advection-dominated accretion flow model.Comment: 18 pages including 4 figures; tentatively scheduled for the March 10, 2000 issue of ApJ; minor revision

    Validation of the questionnaire on beliefs about medication with type 2 diabetic patients

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    O presente trabalho teve como objectivo validar o QuestionĂĄrio Crenças sobre a Medicação, que avalia Crenças Gerais e Crenças EspecĂ­ficas, estudando suas propriedades psicomĂ©tricas em uma amostra de 387 pacientes diabĂ©ticos tipo 2. O estudo de validade para as Crenças Gerais revelou uma solução de um factor, com um alfa de 0,76, e para as Crenças EspecĂ­ficas, dois factores – Necessidades e PreocupaçÔes –, com um alfa de 0,77 e 0,69 respectivamente. Quanto Ă  validade de constructo, verificou-se uma relação entre as Crenças Gerais e a subescala Necessidades das Crenças EspecĂ­ficas com AdesĂŁo Ă  Medicação, avaliada pela Escala de Avaliação de AderĂȘncia MĂ©dica. O instrumento apresenta boas qualidades psicomĂ©tricas para ser utilizado em pacientes diabĂ©ticos tipo 2.The present paper focused on the validation of the Questionnaire on Beliefs about Medication, which assesses both General Beliefs and Specific Beliefs. The psychometric properties of the instrument were analyzed on a sample of 387 type 2 diabetic patients. The validity study for General Beliefs found a unifactorial solution, with an alpha of .76, and for Specific Beliefs, a two-factor solution – Necessities and Concern –, with an alpha of .77 and .69, respectively. In terms of construct validity, a relationship between General Beliefs, subscale Necessities from Specific Beliefs, and adherence to medication, as evaluated by Medical Adherence Rating Scale, was found. The instrument presents good psychometric qualities to be used in type 2 diabetic patients.Fundação para a CiĂȘncia e Tecnologia (FCT

    Accretion column structure of magnetic cataclysmic variables from X-ray spectroscopy

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    Using Chandra HETG data we present light curves for individual spectral lines of Mg XI and Mg XII for EX Hydrae, an intermediate-polar type cataclysmic variable. The Mg XI light curve, folded on the white dwarf spin period, shows two spikes that are not seen in the Mg XII or broad-band light curves. Occultation of the accretion column by the body of the white dwarf would produce such spikes for an angle between the rotation axis and the accretion columns of alpha = 18 degrees and a height of the Mg XI emission above the white dwarf surface of < 0.0004 white dwarf radii or < 4 km. The absence of spikes in the Mg XII and broad-band light curves could then be explained if the bulk of its emission forms at much larger height, > 0.004 white dwarf radii or > 40 km, above the white dwarf surface, although this is not consistent with the predictions of the standard Aizu model of the accretion column.Comment: 12 pages, 3 figures, accepted for publication in the ApJ Letter

    On the Rotating Charged Black String Solution

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    A rotating charged black string solution in the low energy effective field theory describing five dimensional heterotic string theory is constructed. The solution is labelled by mass, electric charge, axion charge and angular momentum per unit length. The extremal limit of this solution is also studied.Comment: 12 pages, IMSC-93/6,(Phyzzx macro), January 199

    Delays in help seeking at the onset of the symptoms of rheumatoid arthritis: a systematic synthesis of qualitative literature

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    A systematic review of qualitative peer-reviewed publications was conducted to identify drivers of and barriers to help-seeking behaviour in adults with new-onset rheumatoid arthritis (RA). 1058 abstracts were searched to identify relevant publications. 21 relevant publications were identified assessed for quality and subjected to analysis informed by thematic and grounded theory frameworks. Several interacting themes were identified including the early experience of symptoms in relation to disease prototypes, minimising the impact of symptoms, speaking to others, gathering information and seeking alternative treatments, and issues related to accessing health services and attitudes towards healthcare professionals. Many people suggested that they had little knowledge of RA before diagnosis, believing RA to be a mild condition that affected older people. These misperceptions made correct symptom interpretation unlikely. Normalising and ignoring symptoms led people to delay in help-seeking. However, when symptoms impacted on daily activities help was usually sought. Individual interpretations of symptoms are both drivers of and barriers to help seeking. Targeted public health interventions are required to inform symptom interpretation and reduce delays
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