333 research outputs found

    Digital second-order phase-locked loop

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    A digital second-order phase-locked loop is disclosed in which a counter driven by a stable clock pulse source is used to generate a reference waveform of the same frequency as an incoming waveform, and to sample the incoming waveform at zero-crossover points. The samples are converted to digital form and accumulated over M cycles, reversing the sign of every second sample. After every M cycles, the accumulated value of samples is hard limited to a value SGN = + or - 1 and multiplied by a value delta sub 1 equal to a number of n sub 1 of fractions of a cycle. An error signal is used to advance or retard the counter according to the sign of the sum by an amount equal to the sum

    Probing linguistic change in Arabic vernaculars: a sociohistorical perspective

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    It is received wisdom in variationist sociolinguistics that linguistic and social factors go hand in hand in structuring variability in language and any consequent instances of language change. We address the complexity of such factors by exploring data from several Arabic dialects in the eastern Arab World. We demonstrate that language change does not always follow expected phonological trajectories, even in cases where older changes are reconstructed to have operated along so-called universal patterns. In our explanation of recent changes in these dialects, we emphasise the role of social motivations for language change and the interactions between these social constraints and purely linguistic ones. Our analysis of change is supported by historical accounts of variation and change in Arabic. We illustrate how general principles of sociolinguistic theory apply to the Arabic data and provide additional layers of sociolinguistic information that highlight the importance of diverse data for evaluating cross-linguistic generalisations

    Black-holes, topological strings and large N phase transitions

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    The counting of microstates of BPS black-holes on local Calabi-Yau of the form O(p2)O(p)S2{\mathcal O}(p-2)\oplus{\mathcal O}(-p) \longrightarrow S^2 is explored by computing the partition function of q-deformed Yang-Mills theory on S2S^2. We obtain, at finite NN, the instanton expansion of the gauge theory. It can be written exactly as the partition function for U(N) Chern-Simons gauge theory on a Lens space, summed over all non-trivial vacua, plus a tower of non-perturbative instanton contributions. In the large NN limit we find a peculiar phase structure in the model. At weak string coupling the theory reduces to the trivial sector and the topological string partition function on the resolved conifold is reproduced in this regime. At a certain critical point, instantons are enhanced and the theory undergoes a phase transition into a strong coupling regime. The transition from the strong coupling phase to the weak coupling phase is of third order.Comment: 16 pages, 3 figures; Invited talk given at QG05, Cala Gonone (Italy), September 200

    Concomitant optic nerve transection and chorioretinitis sclopetaria

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    BACKGROUND: Optic nerve transection and chorioretinitis sclopetaria may occur following blunt ocular trauma. However, simultaneous occurrence has not yet been reported. We report the first case of concomitant optic nerve transection and chorioretinitis sclopetaria. CASE PRESENTATION: A 12- year- old boy with history of BB gun injury to his right eye was referred for loss of vision. His visual acuity was counting fingers at one meter in the right eye and with 3+ relative afferent pupillary defect (RAPD). On slit lamp examination, the right eye appeared normal except for 1+ vitreous reaction. Fundus examination of the right eye revealed a pale disc with superior retinal scar and diffuse submacular fibrosis compatible with chorioretinitis sclopetaria. Orbital CT- scans showed transection of the optic nerve by the BB gun pellet, which was lodged at the orbital apex. CONCLUSION: BB gun injury may cause concomitant optic nerve transection and chorioretinitissclopetaria

    Black Holes and Causal Structure in Anti-de Sitter Isometric Spacetimes

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    The observation that the 2+1 dimensional BTZ black hole can be obtained as a quotient space of anti-de Sitter space leads one to ask what causal behaviour other such quotient spaces can display. In this paper we answer this question in 2+1 and 3+1 dimensions when the identification group has one generator. Among other things we find that there does not exist any 3+1 generalization of the rotating BTZ hole. However, the non-rotating generalization exists and exhibits some unexpected properties. For example, it turns out to be non-static and to possess a non-trivial apparent horizon.Comment: LaTeX, 22 pages, 10 postscript figures, uses epsf.te

    Effects of different biochars, compost and lime treatments on the chemical properties of sandy soils

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    Decrease in organic matter of the soil is one of the major threats to soils in Europe and other parts of the globe. Maintaining or increasing organic carbon is a great challenge in agricultural practices. Application of composts and other organic amendments is an important way of compensation of losses of organic carbon at the same time it is solving the placement and recycling of organic wastes and residues. The favorable effect of these amendments on physical, chemical and biological properties has been proved by different studies, however the stability and the rate of the influence is an issue that can be improved.The aim of the presented study was to investigate the effect of carbonates on the solubility of applied organic materials and selected soil parameters. Different biochars, compost and carbonate were added to light textured soil. The pH and E4/E6 rates were studied under laboratory conditions. Beside the increase of soil organic matter content, all studied parameters gave promising results. The decrease in E4/E6 rate suggests that the inorganic carbonates are stabilizing the fresh organic residues and prevent the leaching processes. Improved soil organic carbon stability is very important in light textured soils.Further investigations are undergoing to determine the optimal rate of components and extend the kinds of material available for application

    New Prehospital Triage for Stroke Patients Significantly Reduces Transport Time of EVT Patients Without Delaying IVT

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    Background and Purpose: Ischemic stroke is a leading cause of mortality and morbidity worldwide. The time from stroke onset to treatment impacts clinical outcome. Here, we examined whether changing a triage model from “drip and ship” to “mothership” yielded significant reductions of onset-to-groin time (OGT) in patients receiving EVT and onset-to-needle time (ONT) in IVT-treated patients, compared to before FAST-PLUS test implementation. We also investigated whether the new triage improved clinical outcomes.Methods: In a before/after multicenter study, we evaluated the effects of changing the prehospital triage system for suspected stroke patients in the Moravian–Silesian region, Czech Republic. In the new system, the validated FAST PLUS test is used to differentiate patients with suspected large vessel occlusion and triage-positive patients are transported directly to the CSC. Time metrics and patient data were obtained from the regional EMS database and SITS database.Results: For EVT patients, the median OGT was 213 min in 2015 and 142 min in 2018, and the median TT was 142 min in 2015 and 47 min in 2018. For tPA patients, the median ONT was 110 min in 2015 and 109 min in 2018, and the median TT was 41 min in 2015 and 48 min in 2018. Clinical outcome did not significantly change. The percentages of patients with favorable clinical outcome (mRS 0–2) were comparable between 2015 and 2018: 60 vs. 59% in tPA patients and 40 vs. 44% in EVT patients.Conclusions: The new prehospital triage has yielded shorter OGTs for EVT patients. No changes were found in the onset-to-needle time for IVT-treated patients, or in the clinical outcome at 3 months after stroke onset

    The nanosyntax of spatial deixis

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    This paper provides a fine-grained morphosyntactic analysis of spatial deixis. We propose that the universal core of spatial deixis is a three-way contrast: Proximal close to speaker', Medial close to hearer', and Distal far from speaker and hearer'. This system arises from three features merged as heads in a single universal functional sequence: Dx(3) > Dx(2) > Dx(1). The hierarchy is understood in terms of superset-subset relations, such that Proximal [Dx(1)] is a subset of Medial [Dx(2) [Dx(1)]], which in turn is a subset of Distal [Dx(3) [Dx(2) [Dx(1)]]]. Evidence comes from patterns of syncretism and morphological containment in the demonstrative systems of a number of genetically diverse languages. Regarding syncretisms, languages can show a transparent three-way morphological contrast, or some sort of syncretism: Medial/Proximal vs. Distal, Distal/Medial vs. Proximal, or a totally syncretic Distal/Medial/Proximal (i.e. a neutral demonstrative). These syncretisms entail that the features responsible for the Proximal and Medial readings be adjacent and that the features responsible for the Distal and Medial readings be adjacent in the fseq. Regarding containment, we show that Proximal can be structurally contained within Medial and that Medial can be structurally contained within Distal, meaning that Medial structures are larger than Proximal structures, and that Distal structures are larger than Medial structures, confirming our hierarchy. We show that these facts are naturally accounted for by nanosyntactic principles of spellout. We end the paper by accounting for potential counterexamples and other issues

    Social integration and dialect divergence in coastal Palestine

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    The history of Palestine has caused communities to be displaced and relocated, entailing that speech communities have been dismantled and created anew. The coastal cities of Jaffa and Gaza exemplify this reality. This study analyzes speakers from Jaffa, some of whom remained there and others residing in Gaza as refugees. Through an examination of three variables, (ʕ), (AH), and (Q), we shed light on the effects of dialect contact while highlighting the link between dialect contact and identity formation and maintenance. All three variables are found to be in varied states of change as a result of contact with other varieties of Arabic, as well as with Modern Hebrew. We conclude that (Q), through its high social salience, works to create and maintain a sense of community identity for Jaffan refugees in Gaza at a time when the speech of the larger Jaffa community is undergoing substantial linguistic change
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