Notions and subnotions in information structure

Three dimensions can be distinguished in a cross-linguistic account of information structure. First, there is the definition of the focus constituent, the part of the linguistic expression which is subject to some focus meaning. Second and third, there are the focus meanings and the array of structural devices that encode them. In a given language, the expression of focus is facilitated as well as constrained by the grammar within which the focus devices operate. The prevalence of focus ambiguity, the structural inability to make focus distinctions, will thus vary across languages, and within a language, across focus meanings

Low altitude flux and dose measurements during two solar flare events

The dosimeter on board the low altitude polar orbiting DMSP/F7 satellite makes dose and flux measurements for electrons with energies greater than 1.0, 2.5, 5.0 and 10.0 MeV; and for protons with energies greater than 20, 35, 51, and 75 MeV. The characteristics and performance of the dosimeter are illustrated by presenting dose and flux data taken during the solar flare proton events of February 16 and April 26, 1984

Diagnosis of atrial situs by transesophageal echocardiography

AbstractIn a prospective investigation, direct visualization of both atrial appendages was attempted during transesophageal echocardiographic studies in 132 patients with congenital heart disease. High quality cross-sectional images delineating the unique morphologic details of both atrial appendages were obtained in every patient. Abnormal cardiac position such as dextrocardia (four patients) or mesocardia (two patients) did not pose any problems for transesophageal assessment of both atrial appendages. Thus, direct diagnosis of atrial situs was possible in every patient. Atrial situs solitus was present in 127 patients studied. Three patients were found to have situs inversus, one had left atrial isomerism and one had right atrial isomerism. No patient with juxtaposed atrial appendages was encountered. All patients had prior subcostal ultrasound scans for assessment of the morphology and relation of the suprarenal abdominal great vessels and the related patterns of hepatic venous drainage.Patients with abnormal atrial situs had correlative high kilovoltage filter beam radiography for assessment of bronchus morphology. The results of situs determination obtained by either method were in agreement.In this series, transesophageal echocardiography allowed the direct and accurate visualization of both atrial appendages and the determination of atrial situs in all patients studied. Transesophageal echocardiography may prove to be the most reliable in vivo technique for determination of atrial situs

A comparison of balloon injury models of endovascular lesions in rat arteries

BACKGROUND: Balloon injury (BI) of the rat carotid artery (CCA) is widely used to study intimal hyperplasia (IH) and decrease in lumen diameter (LD), but CCA's small diameter impedes the evaluation of endovascular therapies. Therefore, we validated BI in the aorta (AA) and iliac artery (CIA) to compare it with CCA. METHODS: Rats underwent BI or a sham procedure (control). Light microscopic evaluation was performed either directly or at 1, 2, 3, 4 and 16 weeks follow-up. The area of IH and the change in LD (LD at 16 weeks minus LD post BI) were compared. RESULTS: In the BI-groups the area of IH increased to 0.14 +/- 0.08 mm2 (CCA), 0.14 +/- 0.03 mm2 (CIA) and 0.12 +/- 0.04 mm2 (AA) at 16 weeks (NS). The LD decreased with 0.49 +/- 0.07 mm (CCA), compared to 0.22 +/- 0.07 mm (CIA) and 0.07 +/- 0.10 mm (AA) at 16 weeks (p < 0.05). The constrictive vascular remodelling (CVR = wall circumference loss combined with a decrease in LD) was -0.17 +/- 0.05 mm in CIA but absent in CCA and AA. No IH, no decrease in LD and no CVR was seen in the control groups. CONCLUSIONS: BI resulted in: (1.) a decrease in LD in CCA due to IH, (2.) a decrease in LD in CIA due to IH and CVR, (3.) no change in LD in AA, (4.) Comparable IH development in all arteries, (5.) CCA has no vasa vasorum compared to CIA and AA, (6.) The CIA model combines good access for 2 F endovascular catheters with a decrease in LD due to IH and CVR after BI

Mechanical features and in vivo imaging of a polymer stent

A polyethylene-terephthalate (PETP, polyester), self-expanding, braided mesh stent has been developed for percutaneous (coronary) arterial implantation. In vitro measurements showed that the radial pressure delivered by this device was similar to a self-expanding, stainless steel stent. Due to hysteresis-like behaviour, it proved necessary to mount the polymer stent on the delivery system immediately before the placement procedure, and to select a diameter in the unconstrained condition, which was 60% larger than the diameter of the target vessel. Eight polyester stents were implanted in peripheral arteries of four pigs. Except for heparin during the implantation procedure, antithrombotic or antiplatelet drugs were not administered. After four weeks repeat angiography revealed that one of the stents was subtotally occluded. At autopsy, two other stents proved to be located in the aortic bifurcation, probably due to failure of the delivery system. Quantitative angiographic assessment showed that the mean luminal diameters at the site of stent placement were 3.3±0.2 mm before, 3.2±0.2 mm immediately after, and 2.7±0.5 mm at four weeks after implantation. Intravascular ultrasound (IVUS) examination after 4 weeks could identify the individual struts of the stents, as well as their length. In addition, a description of the extent of neointimal hyperplasia was feasible. The IVUS assessment was validated by histological examination. In conclusion, polyester stents can be constructed with mechanical properties similar to stainless steel stents. After implantation in porcine peripheral arteries, five of six correctly placed stents were patent at four weeks. Imaging of stents by angiography and IVUS provided complementary information

The Paradoxical Effects of Chronic Intra-Amniotic Ureaplasma parvum Exposure on Ovine Fetal Brain Development

Chorioamnionitis is associated with adverse neurodevelopmental outcomes in preterm infants. Ureaplasma spp. are the microorganisms most frequently isolated from the amniotic fluid of women diagnosed with chorioamnionitis. However, controversy remains concerning the role of Ureaplasma spp. in the pathogenesis of neonatal brain injury. We hypothesize that re-exposure to an inflammatory trigger during the perinatal period might be responsible for the variation in brain outcome of preterms following Ureaplasma driven chorioamnionitis. To investigate these clinical scenarios, we performed a detailed multi-modal study in which ovine neurodevelopmental outcomes were assessed following chronic intra-amniotic Ureaplasma parvum (UP) infection, either alone or combined with subsequent lipopolysaccharide (LPS) exposure. We show that chronic intra-amniotic UP exposure during the second trimester provoked a decrease of astrocytes, increased oligodendrocyte numbers and elevated 5-methylcytosine levels. In contrast, short-term LPS exposure before preterm birth induced increased microglial activation, myelin loss, elevation of 5-hydroxymethylcytosine levels and lipid profile changes. These LPS-induced changes were prevented by chronic pre-exposure to UP (preconditioning). These data indicate that chronic UP exposure provokes dual effects on preterm brain development in utero. On one hand, prolonged UP exposure causes detrimental cerebral changes which may predispose to adverse postnatal clinical outcomes. On the other, chronic intra-amniotic UP exposure preconditions the brain against a second inflammatory hit. This study demonstrates that microbial interactions, timing and duration of inflammatory insults will determine the effects on the fetal brain. Therefore, this study helps to understand the complex and diverse postnatal neurological outcomes following UP driven chorioamnionitis

Neuroinflammation and structural injury of the fetal ovine brain following intra-amniotic Candida albicans exposure.

BackgroundIntra-amniotic Candida albicans (C. Albicans) infection is associated with preterm birth and high morbidity and mortality rates. Survivors are prone to adverse neurodevelopmental outcomes. The mechanisms leading to these adverse neonatal brain outcomes remain largely unknown. To better understand the mechanisms underlying C. albicans-induced fetal brain injury, we studied immunological responses and structural changes of the fetal brain in a well-established translational ovine model of intra-amniotic C. albicans infection. In addition, we tested whether these potential adverse outcomes of the fetal brain were improved in utero by antifungal treatment with fluconazole.MethodsPregnant ewes received an intra-amniotic injection of 10(7) colony-forming units C. albicans or saline (controls) at 3 or 5 days before preterm delivery at 0.8 of gestation (term ~ 150 days). Fetal intra-amniotic/intra-peritoneal injections of fluconazole or saline (controls) were administered 2 days after C. albicans exposure. Post mortem analyses for fungal burden, peripheral immune activation, neuroinflammation, and white matter/neuronal injury were performed to determine the effects of intra-amniotic C. albicans and fluconazole treatment.ResultsIntra-amniotic exposure to C. albicans caused a severe systemic inflammatory response, illustrated by a robust increase of plasma interleukin-6 concentrations. Cerebrospinal fluid cultures were positive for C. albicans in the majority of the 3-day C. albicans-exposed animals whereas no positive cultures were present in the 5-day C. albicans-exposed and fluconazole-treated animals. Although C. albicans was not detected in the brain parenchyma, a neuroinflammatory response in the hippocampus and white matter was seen which was characterized by increased microglial and astrocyte activation. These neuroinflammatory changes were accompanied by structural white matter injury. Intra-amniotic fluconazole reduced fetal mortality but did not attenuate neuroinflammation and white matter injury.ConclusionsIntra-amniotic C. albicans exposure provoked acute systemic and neuroinflammatory responses with concomitant white matter injury. Fluconazole treatment prevented systemic inflammation without attenuating cerebral inflammation and injury

Acoustic Correlates of Information Structure.

This paper reports three studies aimed at addressing three questions about the acoustic correlates of information structure in English: (1) do speakers mark information structure prosodically, and, to the extent they do; (2) what are the acoustic features associated with different aspects of information structure; and (3) how well can listeners retrieve this information from the signal? The information structure of subject-verb-object sentences was manipulated via the questions preceding those sentences: elements in the target sentences were either focused (i.e., the answer to a wh-question) or given (i.e., mentioned in prior discourse); furthermore, focused elements had either an implicit or an explicit contrast set in the discourse; finally, either only the object was focused (narrow object focus) or the entire event was focused (wide focus). The results across all three experiments demonstrated that people reliably mark (1) focus location (subject, verb, or object) using greater intensity, longer duration, and higher mean and maximum F0, and (2) focus breadth, such that narrow object focus is marked with greater intensity, longer duration, and higher mean and maximum F0 on the object than wide focus. Furthermore, when participants are made aware of prosodic ambiguity present across different information structures, they reliably mark focus type, so that contrastively focused elements are produced with greater intensity, longer duration, and lower mean and maximum F0 than noncontrastively focused elements. In addition to having important theoretical consequences for accounts of semantics and prosody, these experiments demonstrate that linear residualisation successfully removes individual differences in people's productions thereby revealing cross-speaker generalisations. Furthermore, discriminant modelling allows us to objectively determine the acoustic features that underlie meaning differences

Basic notions of information structure

This article takes stock of the basic notions of Information Structure (IS). It first provides a general characterization of IS — following Chafe (1976) — within a communicative model of Common Ground(CG), which distinguishes between CG content and CG management. IS is concerned with those features of language that concern the local CG. Second, this paper defines and discusses the notions of Focus (as indicating alternatives) and its various uses, Givenness (as indicating that a denotation is already present in the CG), and Topic (as specifying what a statement is about). It also proposes a new notion, Delimitation, which comprises contrastive topics and frame setters, and indicates that the current conversational move does not entirely satisfy the local communicative needs. It also points out that rhetorical structuring partly belongs to IS.Peer Reviewe

A statistical study of the inner edge of the electron plasma sheet and the net convection potential as a function of geomagnetic activity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94691/1/jgra21076.pd