2,450 research outputs found

    What Can the Organization of the Brain’s Default Mode Network Tell us About Self-Knowledge?

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    Understanding ourselves has been a fundamental topic for psychologists and philosophers alike. In this paper we review the evidence linking specific brain structures to self-reflection. The brain regions most associated with self-reflection are the posterior cingulate and medial prefrontal (mPFC) cortices, together known as the cortical midline structures (CMSs). We review evidence arguing that self-reflection is special in memory, while noting that these brain regions are often engaged when we think about others in our social worlds. Based on the CMSs’ patterns of connectivity and activity, we speculate about three possible interpretations of their role in supporting self-reflection that are somewhat overlapping, and not intended to be mutually exclusive. First, self may be a powerful, but ordinary case for a cognitive system specialized for thinking about people. Second, mPFC may serve as a processing “hub,” binding together information from all sensory modalities with internally generated information. Third, mPFC may serve as a cortical director of thought, helping to guide moment-by-moment conscious processing. Suggestions are made for future research avenues aimed at testing such possibilities

    Interpreting Ambiguous Social Cues in Unpredictable Contexts

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    Unpredictable environments can be anxiety-provoking and elicit exaggerated emotional responses to aversive stimuli. Even neutral stimuli, when presented in an unpredictable fashion, prime anxiety-like behavior and elicit heightened amygdala activity. The amygdala plays a key role in initiating responses to biologically relevant information, such as facial expressions of emotion. While some expressions clearly signal negative (anger) or positive (happy) events, other expressions (e.g. surprise) are more ambiguous in that they can predict either valence, depending on the context. Here, we sought to determine whether unpredictable presentations of ambiguous facial expressions would bias participants to interpret them more negatively. We used functional magnetic resonance imaging and facial electromyography (EMG) to characterize responses to predictable vs unpredictable presentations of surprised faces. We observed moderate but sustained increases in amygdala reactivity to predictable presentations of surprised faces, and relatively increased amygdala responses to unpredictable faces that then habituated, similar to previously observed responses to clearly negative (e.g. fearful) faces. We also observed decreased corrugator EMG responses to predictable surprised face presentations, similar to happy faces, and increased responses to unpredictable surprised face presentations, similar to angry faces. Taken together, these data suggest that unpredictability biases people to interpret ambiguous social cues negatively

    The Nuclear Spectral Energy Distribution of NGC 4395, The Least Luminous Type 1 Seyfert Galaxy

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    We present X-ray (ROSAT), infrared, and radio observations of NGC 4395, which harbors the optically least luminous type 1 Seyfert nucleus discovered thus far. In combination with published optical and ultraviolet spectra, we have used these data to assemble the broadband spectral energy distribution (SED) of the galaxy's nucleus. Interestingly, the SED of NGC 4395 differs markedly from the SEDs of both quasars and typical low-luminosity active galactic nuclei, which may be a manifestation of the different physical conditions (i.e., black hole masses, accretion rates, and/or accretion modes) that exist in these objects. The nuclear X-ray source in NGC 4395 is variable and has an observed luminosity of just ~ 10^38 ergs/s. Although this emission could plausibly be associated with either a weak active nucleus or a bright stellar-mass binary system, the optical and ultraviolet emission-line properties of the nucleus strongly suggest that the X-rays arise from a classical AGN.Comment: Accepted for publication in PASP (July 1999), 17 pages, including 4 Postscript figure

    Effect of a grazing period prior to finishing on a high concentrate diet on meat quality from bulls and steers

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    Bulls and steers (n = 60) were assigned to a pre-finishing grazing period and subsequently finished on concentrates or offered concentrates without grazing until slaughter (19 months). Colour and pH of longissimus thoracis were measured (48 h post-slaughter), and samples collected for proximate composition, collagen, sarcomere length, muscle fibre and enzymatic profile analysis. Steaks for texture, cook loss and sensory were aged (14 days). Castration increased intramuscular fat content, cook loss and myosin isoforms IIa and I proportions, and decreased IIx proportion (P < 0.05). Steer meat was positively correlated to overall tenderness, texture and acceptability (P < 0.05). The presence of a pre-finishing grazing period decreased intramuscular fat and increased the proportion of IIa compared with animals on concentrates, while no differences were found in sensory. Muscle colour, collagen, sarcomere length and instrumental texture were not modified by diet or castration. In conclusion, beef sensory characteristics were unaffected by diet, whereas castration resulted in a small improvement; however all the treatments produced an acceptable product

    Development of and Access to Products for Neglected Diseases

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    INTRODUCTION: Prior research on neglected disease drug development suggested inadequate funding was responsible for relatively few new approvals. In response, significantly more resources have been allocated towards development of drugs targeting neglected diseases. Our objective was to reassess drug development between 1975 and 1999, evaluate progress in neglected disease drug development since 2000, and explain how increased numbers of approvals are a necessary but insufficient condition to improving access. METHODS: To assess numbers of approvals targeting neglected diseases, we employed two distinct methodologies: First, to revisit numbers published in Trouiller et al. (2002) we used their method to count marketed new chemical entities (NCEs) between 1975 and 1999. Second, using the G-Finder report as a benchmark, we identified which diseases are currently considered "neglected" to tally approvals in the 1975-1999 and 2000-2009 periods. Searching PharmaProjects and IMS R&D Focus databases as well as websites from numerous drug regulatory agencies, we identified new drug approvals and indications. Also, we examined the World Health Organization's (WHO) Essential Drug List (EDL) to see which drugs and indications were on the list. FINDINGS: Upon recount, using Trouiller et al. methodology, we found that between 1975 and 1999 more NCEs (n = 32) targeting tropical diseases and tuberculosis were approved than reported in Trouiller et al. (n = 16). Using the G-Finder method of defining neglected diseases, we found 46 new drug approvals between 1975 and 1999. WHO included 85% of these drugs on the EDL. In the period 2000 to May 2009, despite much greater funding, only 26 new drugs and vaccines for neglected diseases were marketed. Of these, WHO placed 50% on the EDL. CONCLUSIONS: Product approvals for neglected diseases have increased, though progress has been uneven, with malaria appearing to benefit most in the short run from increased funding, while less success has been booked in other disease categories. Uneven progress suggests funding could be better targeted, particularly with regard to neglected diseases that have hitherto received scant attention. In addition, policymakers should focus on other aspects related to access. Besides drug development, there are the issues of EDL listing, architecture, availability, affordability, and adoption

    Datastreme Courses: Teacher Enhancement Utilizing Current Environmental Data and the Internet

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    The American Meteorological Society\u27s (AMS) Educational Program seeks to assist the improvement of science education in K-12 classrooms through implementation of the National Science Education Standards. This goal is being accomplished through the offering of three teacher enhancement courses via blended instruction methods. Following course participation each teacher functions as an Earth system science education resource person for his/her colleagues

    The Central Engines of 19 LINERs as Viewed by Chandra

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    Using archival Chandra observations of 19 LINERs we explore the X-ray properties of their inner kiloparsec to determine the origin of their nuclear X-ray emission, to investigate the presence of an AGN, and to identify the power source of the optical emission lines. The relative numbers of LINER types in our sample are similar to those in optical spectroscopic surveys. We find that diffuse, thermal emission is very common and is concentrated within the central few hundred parsec. The average spectra of the hot gas in spirals and ellipticals are very similar to those of normal galaxies. They can be fitted with a thermal plasma (kT~0.5 keV) plus a power law (photon index of 1.3-1.5) model. There are on average 3 detected point sources in their inner kiloparsec with L(0.5-10 keV)~10^37-10^40 erg/s. The average cumulative luminosity functions for sources in spirals and ellipticals are identical to those of normal galaxies. In the innermost circle of 2.5" radius in each galaxy we find an AGN in 12 of the 19 galaxies. The AGNs contribute a median of 60% of the 0.5-10 keV luminosity of the central 2.5" region, they have luminosities of 10^37-10^39 erg/s (Eddington ratios 10^-8 to 10^-5). The ionizing luminosity of the AGNs is not enough to power the observed optical emission lines in this particular sample. Thus, we suggest that the lines are powered either by the mechanical interaction of an AGN jet (or wind) with the circumnuclear gas, or by stellar processes, e.g. photoionization by post-AGB stars or young stars.Comment: Accepted by Ap.J. 23 pages, 8 figures, emulatepj format, images of fig 1 not included, for complete PDF preprint see http://www.astro.psu.edu/users/mce/preprints

    Vitamin D deficiency promotes large rupture-prone abdominal aortic aneurysms and cholecalciferol supplementation limits progression of aneurysms in a mouse model

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    Vitamin D deficiency has been associated with human abdominal aortic aneurysm (AAA); however, its role in AAA pathogenesis is unclear. The aim of the present study was to inves-tigate the effect of vitamin D deficiency on AAA development and examine if administering cholecalciferol (CCF) could limit growth of established AAA within the angiotensin-II (AngII) infused apolipoprotein E-deficient mouse model. Mice were rendered vitamin D deficiency through dietary restriction and during AngII infusion developed larger AAAs as assessed by ultrasound and ex vivo morphometry that ruptured more commonly (48% vs. 19%; P=0.028) than controls. Vitamin D deficiency was associated with increased aortic expression of osteopontin and matrix metalloproteinase-2 and -9 than controls. CCF administration to mice with established aortic aneurysms limited AAA growth as assessed by ultrasound (P<0.001) and ex vivo morphometry (P=0.036) and reduced rupture rate (8% vs. 46%; P=0.031). This effect was associated with up-regulation of circulating and aortic sclerostin. Incubation of human aortic smooth muscle cells with 1,25-dihyroxyvitamin D3 (the active metabolite of vitamin D) for 48 h induced up-regulation of sclerostin (P<0.001) and changed the expression of a range of other genes important in extracellular matrix remodeling. The present study suggests that vitamin D deficiency promotes development of large rupture-prone aortic aneurysms in an experimental model. CCF administration limited both growth and rupture of established aneurysms. These effects of vitamin D appeared to be mediated via changes in genes involved in extracellular matrix remodeling, particularly sclerostin
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