1,101 research outputs found

    The Ineludible non-Gaussianity of the Primordial Black Hole Abundance

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    We study the formation of primordial black holes when they are generated by the collapse of large overdensities in the early universe. Since the density contrast is related to the comoving curvature perturbation by a nonlinear relation, the overdensity statistics is unavoidably non-Gaussian. We show that the abundance of primordial black holes at formation may not be captured by a perturbative approach which retains the first few cumulants of the non-Gaussian probability distribution. We provide two techniques to calculate the non-Gaussian abundance of primordial black holes at formation, one based on peak theory and the other on threshold statistics. Our results show that the unavoidable non-Gaussian nature of the inhomogeneities in the energy density makes it harder to generate PBHs. We provide simple (semi-)analytical expressions to calculate the non-Gaussian abundances of the primordial black holes and show that for both narrow and broad power spectra the gaussian case from threshold statistics is reproduced by increasing the amplitude of the power spectrum by a factor O(2÷3){\cal O}(2\div 3).Comment: 26 pages, 10 figures, matching published versio

    Solution of Massless Spin One Wave Equation in Robertson-Walker Space-time

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    We generalize the quantum spinor wave equation for photon into the curved space-time and discuss the solutions of this equation in Robertson-Walker space-time and compare them with the solution of the Maxwell equations in the same space-time.Comment: 16 Pages, Latex, no figures, An expanded version of paper published in International Journal of Modern Physics A, 17 (2002) 113

    Monitoring sources of event memories: A cross-linguistic investigation

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    When monitoring the origins of their memories, people tend to mistakenly attribute mem- ories generated from internal processes (e.g., imagination, visualization) to perception. Here, we ask whether speaking a language that obligatorily encodes the source of informa- tion might help prevent such errors. We compare speakers of English to speakers of Turkish, a language that obligatorily encodes information source (direct/perceptual vs. indirect/hearsay or inference) for past events. In our experiments, participants reported having seen events that they had only inferred from post-event visual evidence. In general, error rates were higher when visual evidence that gave rise to inferences was relatively close to direct visual evidence. Furthermore, errors persisted even when participants were asked to report the specific sources of their memories. Crucially, these error patterns were equivalent across language groups, suggesting that speaking a language that obligatorily encodes source of information does not increase sensitivity to the distinction between per- ception and inference in event memory

    Speaking and gesturing guide event perception during message conceptualization: Evidence from eye movements

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    Speakers’ visual attention to events is guided by linguistic conceptualization of information in spoken language production and in language-specific ways. Does production of language-specific co-speech gestures further guide speakers’ visual attention during message preparation? Here, we examine the link between visual attention and multimodal event descriptions in Turkish. Turkish is a verb-framed language where speakers’ speech and gesture show language specificity with path of motion mostly expressed within the main verb accompanied by path gestures. Turkish-speaking adults viewed motion events while their eye movements were recorded during non- linguistic (viewing-only) and linguistic (viewing-before-describing) tasks. The relative attention allocated to path over manner was higher in the linguistic task compared to the non-linguistic task. Furthermore, the relative attention allocated to path over manner within the linguistic task was higher when speakers (a) encoded path in the main verb versus outside the verb and (b) used additional path gestures accompanying speech versus not. Results strongly suggest that speakers’ visual attention is guided by language-specific event encoding not only in speech but also in gesture. This provides evidence consistent with models that propose integration of speech and gesture at the conceptualization level of language production and suggests that the links between the eye and the mouth may be extended to the eye and the hand

    Speaking but not gesturing predicts event memory: A cross-linguistic comparison

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    Every day people see, describe, and remember motion events. However, the relation between multimodal encoding of motion events in speech and gesture, and memory is not yet fully understood. Moreover, whether language typology modulates this relation remains to be tested. This study investigates whether the type of motion event information (path or manner) mentioned in speech and gesture predicts which information is remembered and whether this varies across speakers of typologically different languages. Dutch- and Turkish-speakers watched and described motion events and completed a surprise recognition memory task. For both Dutch- and Turkish-speakers, manner memory was at chance level. Participants who mentioned path in speech during encoding were more accurate at detecting changes to the path in the memory task. The relation between mentioning path in speech and path memory did not vary cross-linguistically. Finally, the co-speech gesture did not predict memory above mentioning path in speech. These findings suggest that how speakers describe a motion event in speech is more important than the typology of the speakers’ native language in predicting motion event memory. The motion event videos are available for download for future research at https://osf.io/p8cas/

    Investigation of the peripheral inflammation (neutrophil-lymphocyte ratio) in two neurodegenerative diseases of the central nervous system

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    Introduction: Alzheimer’s disease (AD), and idiopathic Parkinson’s disease (IPD) are the neurodegenerative diseases of the central nervous system (CNS). Cognitive impairment is on the forefront in AD. However, IPD is a movement disorder. Inflammation was suggested to have an effect in the pathophysiology of these two diseases. Neutrophil–lymphocyte ratio (NLR) was shown to be a possible marker showing the peripheral inflammation. We aimed to investigate the NLR of patiens with the diagnosis of AD, and IPD, and individuals with no neurodegenerative disease. Materials and methods: A total of 100 patients with the diagnosis of IPD, and 94 with diagnosis of AD, and 61 healthy controls were included into the study. All the demographic, clinical, and laboratory data were retrospectively obtained from the hospital automated database system. Results: The NLR in the IPD group was found statistically significantly higher compared with the control group and the AD group (p < 0.001, p = 0.04, respectively). The age-adjusted values were statistically analyzed because of age difference. No statistically significant difference was detected between AD and control groups in terms of NLR (p = 0.6). The age-adjusted NLR value in the Parkinson’s group was found significantly higher compared to the control group (p = 0.02) and Alzheimer’s group (p = 0.03). Discussion: Chronic inflammation has an important role in the emergence and progression of the chronic neurodegenerative diseases of the CNS. Our results show that the inflammation in the peripheral blood in IPD was more significant compared with the inflammation in AD. © 2021, Fondazione Società Italiana di Neurologia
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