Kilohertz QPO Peak Separation Is Not Constant in Scorpius X-1

We report on a series of twenty ~10^5 c/s, 0.125 msec time-resolution RXTE observations of the Z source and low-mass X-ray binary Scorpius X-1. Twin kilohertz quasi-periodic oscillation (QPO) peaks are obvious in nearly all observations. We find that the peak separation is not constant, as expected in some beat-frequency models, but instead varies from ~310 to ~230 Hz when the centroid frequency of the higher-frequency peak varies from ~875 to ~1085 Hz. We detect none of the additional QPO peaks at higher frequencies predicted in the photon bubble model (PBM), with best-case upper limits on the peaks' power ratio of 0.025. We do detect, simultaneously with the kHz QPO, additional QPO peaks near 45 and 90 Hz whose frequency increases with mass accretion rate. We interpret these as first and second harmonics of the so-called horizontal-branch oscillations well known from other Z sources and usually interpreted in terms of the magnetospheric beat-frequency model (BFM). We conclude that the magnetospheric BFM and the PBM are now unlikely to explain the kHz QPO in Sco X-1. In order to succeed in doing so, any BFM involving the neutron star spin (unseen in Sco X-1) will have to postulate at least one additional unseen frequency, beating with the spin to produce one of the kHz peaks.Comment: 6 pages including 3 figure

Dale Goble as a Builder of Bridges

Ecological scientists and legal scholars think and talk in different ways. The “gulf of mutual incomprehension” that results can impede efforts to address shared problems. Dale Goble bridged this gulf by teaming with ecologists to interpret the Endangered Species Act and develop the concept of conservation-reliant species—species that require ongoing, long-term management to address the factors that threaten them. Most imperiled species are conservation reliant and conservation resources are limited. Meeting the long-term needs of conservation-reliant species will require the blending of ecological science, societal context, and law that Dale Goble has long promoted

T Pyxidis: The First Cataclysmic Variable with a Collimated Jet

We present the first observational evidence for a collimated jet in a cataclysmic variable system; the recurrent nova T Pyxidis. Optical spectra show bipolar components of H$\alpha$ with velocities $\sim 1400 km/s$, very similar to those observed in the supersoft X-ray sources and in SS 433. We argue that a key ingredient of the formation of jets in the supersoft X-ray sources and T Pyx (in addition to an accretion disk threaded by a vertical magnetic field), is the presence of nuclear burning on the surface of the white dwarf.Comment: 10 pages 2 figures to appear in ApJ Letter

Own Your Politics: The Entanglement of Resistance and the Luxury Fashion Industry

This thesis takes as its subject the increasing instrumentalization of social and political content by the fashion industry in recent years. Such content raises questions about the relationship between notions of political resistance and market capitalism. Marxist theorists such as Frederic Jameson and David Harvey would perhaps view this phenomenon as a confirmation of the ways in which late capitalism incapacitates forms of political descent by absorbing it within its machinations. Within this line of thinking, the way in which various designers use the fashion runway as a forum for protest would suggest late capitalism’s seemingly boundless ability to absorb critique within the commodity form. Such a notion would run parallel to the claim by Jameson that the diversification of cultural production in postmodernism has rendered it illegible. The first chapter illustrates how such notions of absorbed resistance are consistent with the aesthetic project of several influential fashion designers today. The primary example locates this in the trend “normcore.” I will elaborate a history of the term, showing the ways in which New York based art collective “DIS” was instrumental in its formation. I will then show how the trend firmly established itself within canonical fashion aesthetics through the works of several celebrated fashion designers and brands. The notion that the absorption of political descent within the market system indicates an incapacity of social resistance reaches an impasse however, when considering other forms of social resistance. Most notably, the persistence of racial inequality and the cultural output of minority groups advances an ulterior form of resistance whose project, while coterminous with economic exploitation, is not perfectly delineated within its terms. In the second chapter, I engage with such canonical postmodern thinkers as Michel Foucault and Judith Butler in order to think through specific examples of resistance by political outgroups, and their cooption by the fashion industry. Specifically, the popularization of hip hop style in the United States and globally has rendered it vulnerable to cooption by majoritarian groups. This phenomenon in the examples I enumerate has largely gone unaddressed in the fashion industry, and its obfuscation has furthermore aided the critique of absorbed resistance earlier elucidated. The fashion industry has come under increasing scrutiny to rectify its problematic relationship to racial inequality. The protests against police brutality which seek to address racial justice that broke out during the Summer of 2020 have made it necessary for fashion brands to respond in kind, laying out a course of action in order to rectify its ongoing relationship to racial representation and systemic oppression. In the last section of this paper, I will reflect on the ways in which the brands I engage with have responded. In the end, this study emphasizes the way in which a close study of clothing and the fashion industry is relevant to ongoing discussions concerning political resistance within the frame of a market system

H2O and OH gas in the terrestrial planet-forming zones of protoplanetary disks

We present detections of numerous 10-20 micron H2O emission lines from two protoplanetary disks around the T Tauri stars AS 205A and DR Tau, obtained using the InfraRed Spectrograph on the Spitzer Space Telescope. Follow-up 3-5 micron Keck-NIRSPEC data confirm the presence of abundant water and spectrally resolve the lines. We also detect the P4.5 (2.934 micron) and P9.5 (3.179 micron) doublets of OH and 12CO/13CO v=1-0 emission in both sources. Line shapes and LTE models suggest that the emission from all three molecules originates between ~0.5 and 5 AU, and so will provide a new window for understanding the chemical environment during terrestrial planet formation. LTE models also imply significant columns of H2O and OH in the inner disk atmospheres, suggesting physical transport of volatile ices either vertically or radially; while the significant radial extent of the emission stresses the importance of a more complete understanding of non-thermal excitation processes.Comment: 9 pages, 3 figures, 1 table, aastex, to appear in the Astrophysical Journa

The X-ray eclipse of the dwarf nova HT CAS observed by the XMM-Newton satellite: spectral and timing analysis

A cataclysmic variable is a binary system consisting of a white dwarf that accretes material from a secondary object via the Roche-lobe mechanism. In the case of long enough observation, a detailed temporal analysis can be performed, allowing the physical properties of the binary system to be determined. We present an XMM-Newton observation of the dwarf nova HT Cas acquired to resolve the binary system eclipses and constrain the origin of the X-rays observed. We also compare our results with previous ROSAT and ASCA data. After the spectral analysis of the three EPIC camera signals, the observed X-ray light curve was studied with well known techniques and the eclipse contact points obtained. The X-ray spectrum can be described by thermal bremsstrahlung of temperature $kT_1=6.89 \pm 0.23$ keV plus a black-body component (upper limit) with temperature $kT_2=30_{-6}^{+8}$ eV. Neglecting the black-body, the bolometric absorption corrected flux is $F^{\rm{Bol}}=(6.5\pm 0.1)\times10^{-12}$ erg s$^{-1}$ cm$^{-2}$, which, for a distance of HT Cas of 131 pc, corresponds to a bolometric luminosity of $(1.33\pm 0.02)\times10^{31}$ erg s$^{-1}$. The study of the eclipse in the EPIC light curve permits us to constrain the size and location of the X-ray emitting region, which turns out to be close to the white dwarf radius. We measure an X-ray eclipse somewhat smaller (but only at a level of $\simeq 1.5 \sigma$) than the corresponding optical one. If this is the case, we have possibly identified the signature of either high latitude emission or a layer of X-ray emitting material partially obscured by an accretion disk.Comment: Accepted for publication on Astronomy and Astrophysics, 200

The mass of the neutron star in Cyg X-2 (V1341 Cyg)

Cygnus X-2 is one of the brightest and longest known X-ray sources. We present high resolution optical spectroscopy of Cyg X-2 obtained over 4 years which gives an improved mass function of 0.69 +/- 0.03 Msun (1 sigma error). In addition, we resolve the rotationally broadened absorption features of the secondary star for the first time, deriving a rotation speed of vsin(i) = 34.2 +/- 2.5 km per s (1 sigma error) which leads to a mass ratio of q = M_c/M_x = 0.34 +/- 0.04 (1 sigma error), assuming a tidally-locked and Roche lobe-filling secondary). Hence with the lack of X-ray eclipses (i.e. i <~ 73 degrees) we can set firm 95% confidence lower limits to the neutron star mass of M_x > 1.27 Msun and to the companion star mass of M_c > 0.39 Msun. However, by additionally requiring that the companion must exceed 0.75 Msun (as required theoretically to produce a steady low-mass X-ray binary), then M_x > 1.88 Msun and i < 61 degrees (95% confidence lower and upper limit, respectively), thereby making Cyg X-2 the highest mass neutron star measured to date. If confirmed this would set significant constraints on the equation of state of nuclear matter.Comment: 16 pages, 4 figures, ApJ Letters, accepted, LaTeX, aasms4.st

Cortical thickness of planum temporale and pars opercularis in native language tone processing

The present study investigated the relationship between linguistic tone processing and cortical thickness of bilateral planum temporale (PT) and pars opercularis of the inferior frontal gyrus (IFGpo). Swedish tones on word stems function as cues to upcoming endings. Correlating structural brain imaging data with participants’ response time patterns for suffixes, we found that thicker cortex in the left PT was associated with greater reliance on tones to anticipate upcoming inflections on real words. On inflected pseudoword stems, however, the cortical thickness of left IFGpo was associated with tone-suffix processing. Thus cortical thickness of the left PT might play a role in processing tones as part of stored representations for familiar speech segments, most likely when inflected forms are accessed as whole words. In the absence of stored representations, listeners might need to rely on morphosyntactic rules specifying tone-suffix associations, potentially facilitated by greater cortical thickness of left IFGpo

Development and validation of a self-report measure of practical barriers to medication adherence: The medication practical barriers to adherence questionnaire (MPRAQ)

AIM: This study reports the development and validation of a new self-report measure (MPRAQ) that assesses practical barriers to medication adherence. METHODS: MPRAQ comprises fifteen statements describing practical barriers. Responses are scored on a 5-point Likert scale; higher scores indicate more practical barriers. Initial face validity was evaluated by cognitive testing with patients from a diabetes support group. Following refinement, internal reliability and construct validity were assessed in two samples: patients recruited via Amazon mTurk and the Nivel Dutch Healthcare Consumer Panel (COPA). Respondents completed the Beliefs about Medicines Questionnaire (BMQ - general and specific), and Medication Adherence Report Scale (MARS-5). The mTurk sample also completed the Perceived Sensitivity to Medicines questionnaire (PSM), and repeated MPRAQ two weeks later to assess test-retest reliability. RESULTS: Face validity was evaluated in 15 patients (46% female; mean (SD) age 64(12) years). A total of 184 mTurk participants completed the questionnaire (in English) and 334 in COPA (in Dutch). Internal reliability was acceptable (mTurk α=0.89; COPA α=0.94). Construct validity was confirmed, with significant correlation between MPRAQ and BMQ-Specific Concerns (mTurk r=0.546, p<0.0001; COPA r=0.370, p<0.0001); BMQ-General Harm (mTurk r=0.504, p<0.0001; COPA r=0.219, p<0.0001); BMQ-General Overuse (mTurk, r=0.324, p<0.0001; COPA r=0.109, p=0.047), and PSM (mTurk only, r=0.463, p<0.0001), and a negative correlation with MARS-5 (mTurk r=-0.450, p<0.0001; COPA r=-0.260, p<0.0001). MPRAQ did not correlate with BMQ-Specific Necessity or BMQ-General Benefit. Correlation between MPRAQ baseline and 2-week follow-up scores confirmed test-retest reliability (r=0.745, p<0.0001; n=52). CONCLUSION: MPRAQ is a reliable and valid self-report measure of practical adherence barriers

A new mass-ratio for the X-ray Binary X2127+119 in M15?

The luminous low-mass X-ray binary X2127+119 in the core of the globular cluster M15 (NGC 7078), which has an orbital period of 17 hours, has long been assumed to contain a donor star evolving off the main sequence, with a mass of 0.8 solar masses (the main-sequence turn-off mass for M15). We present orbital-phase-resolved spectroscopy of X2127+119 in the H-alpha and He I 6678 spectral region, obtained with the Hubble Space Telescope. We show that these data are incompatible with the assumed masses of X2127+119's component stars. The continuum eclipse is too shallow, indicating that much of the accretion disc remains visible during eclipse, and therefore that the size of the donor star relative to the disc is much smaller in this high-inclination system than the assumed mass-ratio allows. Furthermore, the flux of X2127+119's He I 6678 emission, which has a velocity that implies an association with the stream-disc impact region, remains unchanged through eclipse, implying that material from the impact region is always visible. This should not be possible if the previously-assumed mass ratio is correct. In addition, we do not detect any spectral features from the donor star, which is unexpected for a 0.8 solar-mass sub-giant in a system with a 17-hour period.Comment: 6 pages, 4 figures, accepted by A&