2,953 research outputs found

    Sesquicaesium hemisodium tetra­cyanidoplatinate(II) sesquihydrate

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    The title compound, Cs1.5Na0.5[Pt(CN)4]·1.5H2O, was isolated from solution as a salt. The tetra­cyanidoplatinate (TCP) anions are stacked in a linear quasi-one-dimensional arrangement along the b axis, with Pt⋯Pt inter­actions of 3.6321 (5) Å. The mixed alkali metal TCP contains three distinct alkali metal positions in the structure that do not show any mixed occupancy: Cs1 (site symmetry 2), Cs2 (general position) and Na1 (site symmetry ). The Na+ ion contains an octa­hedral coordination environment composed of two water mol­ecules and four N-terminal cyanides, which serve to bridge TCP anions. The Cs+ cations contain mono- and bicapped square-prismatic environments, where the square prisms are formed from cyanide N atoms with water mol­ecules capping the faces. The 1.5 water mol­ecules per formula unit are a result of two fully occupied sites, one on a general position and one on a twofold rotation axis. Weak hydrogen-bonding inter­actions are observed between one water mol­ecule and terminal N-atom acceptors from TCP, while the second water mol­ecule is not involved in hydrogen bonding

    Seeing the body distorts tactile size perception

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    Vision of the body modulates somatosensation, even when entirely non-informative about stimulation. For example, seeing the body increases tactile spatial acuity, but reduces acute pain. While previous results demonstrate that vision of the body modulates somatosensory sensitivity, it is unknown whether vision also affects metric properties of touch, and if so how. This study investigated how non-informative vision of the body modulates tactile size perception. We used the mirror box illusion to induce the illusion that participants were directly seeing their stimulated left hand, though they actually saw their reflected right hand. We manipulated whether participants: (a) had the illusion of directly seeing their stimulated left hand, (b) had the illusion of seeing a non-body object at the same location, or (c) looked directly at their non-stimulated right-hand. Participants made verbal estimates of the perceived distance between two tactile stimuli presented simultaneously to the dorsum of the left hand, either 20, 30, or 40 mm apart. Vision of the body significantly reduced the perceived size of touch, compared to vision of the object or of the contralateral hand. In contrast, no apparent changes of perceived hand size were found. These results show that seeing the body distorts tactile size perception

    Implicit body representations and the conscious body image

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    Recent studies have revealed that somatosensory processing relies on a class of implicit body representations showing large distortions of size and shape. The relation between these representations and the conscious body image remains unclear. Dissociations have been reported in the clinical literature on eating disorders between different body image measures, with larger and more consistent distortions found with depictive measures, in which participants compare their body to a visual depiction of a body, than metric measures, in which participants compare their body to some non-body standard. Here, we compared implicit body representations underlying position sense to the body image measured with both depictive and metric methods. The body image was measured using both a depictive method (template matching) in which participants judged whether their hand was wider or more slender than a shown hand picture, and a metric method (line length) in which participants judged whether different parts of the their hand were shorter or longer than a presented line. Consistent with previous findings, characteristic distortions were found for the implicit body representation underlying position sense. These distortions were also found in attenuated form for metric – but not depictive – body image measures. While replicating the basic dissociation between implicit body representations and the conscious body image, these results demonstrate that this dissociation is not absolute and specific tasks may utilise both to varying degrees depending on task demands. Metric measures may not be pure measures of body image, but some combination of visual and somatosensory body representations

    Categorical perception of tactile distance

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    The tactile surface forms a continuous sheet covering the body. And yet, the perceived distance between two touches varies across stimulation sites. Perceived tactile distance is larger when stimuli cross over the wrist, compared to when both fall on either the hand or the forearm. This effect could reflect a categorical distortion of tactile space across body-part boundaries (in which stimuli crossing the wrist boundary are perceptually elongated) or may simply reflect a localised increased in acuity surrounding anatomical landmarks (in which stimuli near the wrist are perceptually elongated). We tested these two interpretations, by comparing a well-documented bias to perceive mediolateral tactile distances across the forearm/hand as larger than proximodistal ones along the forearm/hand at three different sites (hand, wrist, and forearm). According to the ‘categorical’ interpretation, tactile distances should be elongated selectively in the proximodistal axis thus reducing the anisotropy. According to the ‘localised acuity’ interpretation, distances will be perceptually elongated in the vicinity of the wrist regardless of orientation, leading to increased overall size without affecting anisotropy. Consistent with the categorical account, we found a reduction in the magnitude of anisotropy at the wrist, with no evidence of a corresponding specialized increase in precision. These findings demonstrate that we reference touch to a representation of the body that is categorically segmented into discrete parts, which consequently influences the perception of tactile distance

    Ultra-Dense Neutron Star Matter, Strange Quark Stars, and the Nuclear Equation of State

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    With central densities way above the density of atomic nuclei, neutron stars contain matter in one of the densest forms found in the universe. Depending of the density reached in the cores of neutron stars, they may contain stable phases of exotic matter found nowhere else in space. This article gives a brief overview of the phases of ultra-dense matter predicted to exist deep inside neutron stars and discusses the equation of state associated with such matter.Comment: 15 pages, 9 figures; paper presented at the International Symposium on Heavy Ion Physics 2006, April 3 to April 6, 2006, Frankfurt am Main, German

    What Sexual and Gender Minority People Want Researchers to Know About Sexual Orientation and Gender Identity Questions: A Qualitative Study

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    Sexual and gender minority (SGM) people—including members of the lesbian, gay, bisexual, transgender, and queer communities—are understudied and underrepresented in research. Current sexual orientation and gender identity (SOGI) questions do not sufficiently engage SGM people, and there is a critical gap in understanding how SOGI questions reduce inclusion and accurate empirical representation. We conducted a qualitative study to answer the question, “For SGM people, what are the major limitations with current SOGI questions?” Focus groups probed reactions to SOGI questions adapted from prior national surveys and clinical best practice guidelines. Questions were refined and presented in semi-structured cognitive interviews. Template analysis using a priori themes guided analysis. There were 74 participants: 55 in nine focus groups and 19 in cognitive interviews. Participants were diverse: 51.3% identified as gender minorities, 87.8% as sexual minorities, 8.1% as Hispanic/Latinx, 13.5% as Black or African-American, and 43.2% as Non-white. Two major themes emerged: (1) SOGI questions did not allow for identity fluidity and complexity, reducing inclusion and representation, and (2) SOGI question stems and answer choices were often not clear as to which SOGI dimension was being assessed. To our knowledge, this represents the largest body of qualitative data studying SGM perspectives when responding to SOGI questions. We present recommendations for future development and use of SOGI measures. Attention to these topics may improve meaningful participation of SGM people in research and implementation of such research within and for SGM communities

    A supramodal representation of the body surface

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    The ability to accurately localize both tactile and painful sensations on the body is one of the most important functions of the somatosensory system. Most accounts of localization refer to the systematic spatial relation between skin receptors and cortical neurons. The topographic organization of somatosensory neurons in the brain provides a map of the sensory surface. However, systematic distortions in perceptual localization tasks suggest that localizing a somatosensory stimulus involves more than simply identifying specific active neural populations within a somatotopic map. Thus, perceptual localization may depend on both afferent inputs and other unknown factors. In four experiments, we investigated whether localization biases vary according to the specific skin regions and subset of afferent fibers stimulated. We represented localization errors as a ‘perceptual map’ of skin locations. We compared the perceptual maps of stimuli that activate Aβ (innocuous touch), Aδ (pinprick pain), and C fibers (non-painful heat) on both the hairy and glabrous skin of the left hand. Perceptual maps exhibited systematic distortions that strongly depended on the skin region stimulated. We found systematic distal and radial (i.e., towards the thumb) biases in localization of touch, pain, and heat on the hand dorsum. A less consistent proximal bias was found on the palm. These distortions were independent of the population of afferent fibers stimulated, and also independent of the response modality used to report localization. We argue that these biases are likely to have a central origin, and result from a supramodal representation of the body surface

    Implicit and explicit body representations

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    Several forms of perception require that sensory information be referenced to representations of the size and shape of the body. This requirement is especially acute in somatosensation in which the main receptor surface (i.e., the skin) is itself coextensive with the body. In this paper I will review recent research investigating the body representations underlying somatosensory information processing, including abilities such as tactile localisation, tactile size perception, and position sense. These representations show remarkably large and stereotyped distortions of represented body size and shape. Intriguingly, these distortions appear to mirror distortions characteristic of somatosensory maps, though in attenuated form. In contrast, when asked to make overt judgments about perceived body form, participants are generally quite accurate. This pattern of results suggests that higher-level somatosensory processing relies on a class of implicit body representation, distinct from the conscious body image. I discuss the implications of these results for understanding the nature of body representation and the factors which influence it
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