215 research outputs found
A Binary Millisecond Pulsar in Globular Cluster NGC6544
We report the detection of a new 3.06 ms binary pulsar in the globular
cluster NGC6544 using a Fourier-domain ``acceleration'' search. With an implied
companion mass of ~0.01 solar masses and an orbital period of only P_b~1.7
hours, it displays very similar orbital properties to many pulsars which are
eclipsed by their companion winds. The orbital period is the second shortest of
known binary pulsars after 47 Tuc R. The measured flux density of 1.3 +/- 0.4
mJy at 1332 MHz indicates that the pulsar is almost certainly the known
steep-spectrum point source near the core of NGC6544.Comment: Accepted by ApJ Letters on 11 October 2000, 5 page
A Stellar Dynamical Measurement of the Black Hole Mass in the Maser Galaxy NGC 4258
We determine the mass of the black hole at the center of the spiral galaxy
NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These
models are constrained by high spatial resolution imaging and long-slit
spectroscopy of the nuclear region obtained with the {\em Hubble Space
Telescope}, complemented by ground-based observations extending to larger
radii. Our best mass estimate is \MBH = (3.3 \pm 0.2) \times 10^7 \MSun for
a distance of 7.28 Mpc (statistical errors only). This is within 15% of
(3.82\pm 0.01) \times 10^7 \MSun, the mass determined from the kinematics of
water masers (rescaled to the same distance) assuming they are in Keplerian
rotation in a warped disk. The construction of accurate dynamical models of NGC
4258 is somewhat compromised by an unresolved active nucleus and color
gradients, the latter caused by variations in the stellar population and/or
obscuring dust. These problems are not present in the other black
hole mass determinations from stellar dynamics that have been published by us
and other groups; thus, the relatively close agreement between the stellar
dynamical mass and the maser mass in NGC 4258 enhances our confidence in the
black hole masses determined in other galaxies from stellar dynamics using
similar methods and data of comparable quality.Comment: 58 pages, submitted to ApJ. Some figures excluded due to size. The
entire paper is at http://www.noao.edu/noao/staff/lauer/nuker_papers.htm
A Search for H2O Megamasers in High-z Type-2 AGNs
We report a search for H2O megamasers in 274 SDSS type-2 AGNs (0.3 < z <
0.83), half of which can be classified as type-2 QSOs from their [OIII] 5007
luminosity, using the Robert C. Byrd Green Bank Telescope (GBT) and the
Effelsberg 100-m radio telescope. Apart from the detection of the extremely
luminous water vapor megamaser SDSS J080430.99+360718.1, already reported by
Barvainis & Antonucci (2005), we do not find any additional line emission. This
high rate of non-detections is compared to the water maser luminosity function
created from the 78 water maser galaxies known to date and its extrapolation
towards the higher luminosities of "gigamasers" that we would have been able to
detect given the sensitivity of our survey. The properties of the known water
masers are summarized and discussed with respect to the nature of high-z type-2
AGNs and megamasers in general. In the appendix, we list 173 additional objects
(mainly radio galaxies, but also QSOs and galaxies) that were observed with the
GBT, the Effelsberg 100-m radio telescope, or Arecibo Observatory without
leading to the detection of water maser emission.Comment: 28 pages, 3 figures. Accepted for publication in the Astrophysical
Journa
2006 Senior Researcher Award Acceptance Address: Observations about Music Education Research in MENC'S First and Second Centuries
Sport, genetics and the `natural athlete': The resurgence of racial science
This article explores the ethical implications of recent discussions that naturalize the relationship between race, the body and sport within the frame of genetic science. Many suggestions of a racially distributed genetic basis for athletic ability and performance are strategically posited as a resounding critique of the `politically correct' meta-narratives of established sociological and anthropological forms of explanation that emphasize the social and cultural construction of race. I argue that this use of genetic science in order to describe and explain common-sense impressions of racial physiology and sporting ability is founded on erroneous premises of objectivity and disinterest, and inflates the analytical efficacy of scientific truth claims. I suggest that assertions of a value-free science of racial athletic ability reify race as inherited permanent biological characteristics that produce social hierarchies and are more characteristic of a longer history of `racial science'
A Potential Neural Substrate for Processing Functional Classes of Complex Acoustic Signals
Categorization is essential to all cognitive processes, but identifying the neural substrates underlying categorization processes is a real challenge. Among animals that have been shown to be able of categorization, songbirds are particularly interesting because they provide researchers with clear examples of categories of acoustic signals allowing different levels of recognition, and they possess a system of specialized brain structures found only in birds that learn to sing: the song system. Moreover, an avian brain nucleus that is analogous to the mammalian secondary auditory cortex (the caudo-medial nidopallium, or NCM) has recently emerged as a plausible site for sensory representation of birdsong, and appears as a well positioned brain region for categorization of songs. Hence, we tested responses in this non-primary, associative area to clear and distinct classes of songs with different functions and social values, and for a possible correspondence between these responses and the functional aspects of songs, in a highly social songbird species: the European starling. Our results clearly show differential neuronal responses to the ethologically defined classes of songs, both in the number of neurons responding, and in the response magnitude of these neurons. Most importantly, these differential responses corresponded to the functional classes of songs, with increasing activation from non-specific to species-specific and from species-specific to individual-specific sounds. These data therefore suggest a potential neural substrate for sorting natural communication signals into categories, and for individual vocal recognition of same-species members. Given the many parallels that exist between birdsong and speech, these results may contribute to a better understanding of the neural bases of speech
A Program for At-Risk High School Students Informed by Evolutionary Science
Improving the academic performance of at-risk high school students has proven difficult, often calling for an extended day, extended school year, and other expensive measures. Here we report the results of a program for at-risk 9th and 10th graders in Binghamton, New York, called the Regents Academy that takes place during the normal school day and year. The design of the program is informed by the evolutionary dynamics of cooperation and learning, in general and for our species as a unique product of biocultural evolution. Not only did the Regents Academy students outperform their comparison group in a randomized control design, but they performed on a par with the average high school student in Binghamton on state-mandated exams. All students can benefit from the social environment provided for at-risk students at the Regents Academy, which is within the reach of most public school districts
From Harm to Robustness: A Principled Approach to Vice Regulation
John Stuart Mill’s harm principle maintains that adult behavior cannot justifiably be subject to social coercion unless the behavior involves harm or a significant risk of harm to non-consenting others. The absence of harms to others, however, is one of the distinguishing features of many manifestations of “vices” such as the consumption of alcohol, nicotine, recreational drugs, prostitution, pornography, and gambling. It is with respect to vice policy, then, that the harm principle tends to be most constraining, and some current vice controls, such as prohibitions on drug possession and prostitution, violate Mill’s precept. In the vice arena, we seem to be willing to accept social interference with what Mill termed “self-regarding” behavior. But does that willingness then imply that any social intervention into private affairs is justifiable, that the government has just as much right to outlaw Protestantism, or shag carpets, or spicy foods, as it does to outlaw drugs? In this paper I argue that advances in neuroscience and behavioral economics offer strong evidence that vices and other potentially addictive goods or activities frequently involve less-than-rational choices, and hence are exempt from the full force of the harm principle. As an alternative guide to vice policy, and following some guidance from Mill, I propose the “robustness principle”: public policy towards addictive or vicious activities engaged in by adults should be robust with respect to departures from full rationality. That is, policies should work pretty well if everyone is completely rational, and policies should work pretty well even if many people are occasionally (or frequently) irrational in their vice-related choices. The harm and robustness principles cohere in many ways, but the robustness principle offers more scope for policies that try to direct people “for their own good,” without opening the door to tyrannical inroads upon self-regarding behavior
Challenging Incommensurability: What We Can Learn from Ludwik Fleck for the Analysis of Configurational Innovation
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