Head rotations in the play of Hanuman langurs (Semnopithecus entellus): description and analysis of function

Although head rotations are frequent patterns in play behavior in many mammalian species and differ from head movements used in other contexts, they have not been quantitatively described and their function remains unclear. The head rotations occurring in the play behavior of free-ranging Hanuman langurs (Semnopithecus entellus) were described from videotaped sequences. The authors tested 2 possible hypotheses about their function. Either the head rotations serve to create unexpected situations and should therefore occur in both solitary and social play and also be very variable, or they serve as play signals and should therefore occur only in social play and be ritualized. If head rotations have both functions, they should be less variable in social play. The data revealed that head rotations were very variable and were present both in solitary and social play. Furthermore, there was no difference in the variability between the head rotations present in the 2 types of play. The results do not support the function of head rotations as play signals but, rather, suggest that head rotations may serve to create unexpected situations in play.     

Tonal centers and expectancy: facilitation or inhibition of chords at the top of the harmonic hierarchy?

Harmonic priming studies have shown that a musical context with its tonal center influences target chord processing. In comparison with targets following baseline contexts, which do not establish a specific tonal center, processing is facilitated for a strongly related target functioning as the tonic, but inhibited for unrelated (out-of-key) and less related (subdominant) targets. This study investigated cost and benefit patterns for the processing of the 3 most important chords of the harmonic hierarchy. Response time patterns reflected the chords' ranking: Processing was fastest for the tonic, followed by the dominant, and then the subdominant. The comparison with baseline contexts replicated the benefit of processing for tonic targets (Experiments 1 and 3) and the cost of processing for subdominant targets (Experiment 3), while dominant targets were situated at baseline level (Experiments 1 to 3). Findings indicate that listeners implicitly understand fine differences in tonal stabilities and confirm the special status of the tonic being the most expected and solely facilitated chord at the end of a tonal context. Findings are discussed with references to sensory and cognitive approaches of music perception.     

Solving the $100 modal logic challenge

We present the theoretical foundation, design, and implementation, of a system that automatically determines the subset relation between two given axiomatizations of propositional modal logics. This is an open problem for automated theorem proving. Our system solves all but six out of 121 instances formed from 11 common axiomatizations of seven modal logics. Thus, although the problem is undecidable in general, our approach is empirically successful in practically relevant situations.     

A note on the normal form of closed formulas of interpretability logic

Each closed (i.e. variable free) formula of interpretability logic is equivalent in ILF to a closed formula of the provability logic G, thus to a Boolean combination of formulas of the form ⁿ.     

The Proof by Cases Property and its Variants in Structural Consequence Relations

This paper is a contribution to the study of the rôle of disjunction in Abstract Algebraic Logic. Several kinds of (generalized) disjunctions, usually defined using a suitable variant of the proof by cases property, were introduced and extensively studied in the literature mainly in the context of finitary logics. The goals of this paper are to extend these results to all logics, to systematize the multitude of notions of disjunction (both those already considered in the literature and those introduced in this paper), and to show several interesting applications allowed by the presence of a suitable disjunction in a given logic.     

Responses of urban crows to con- and hetero-specific alarm calls in predator and non-predator zoo enclosures

Urban animals and birds in particular are able to cope with diverse novel threats in a city environment such as avoiding novel, unfamiliar predators. Predator avoidance often includes alarm signals that can be used also by hetero-specifics, which is mainly the case in mixed-species flocks. It can also occur when species do not form flocks but co-occur together. In this study we tested whether urban crows use alarm calls of conspecifics and hetero-specifics (jackdaws, Corvus monedula) differently in a predator and a non-predator context with partly novel and unfamiliar zoo animal species. Birds were tested at the Tiergarten Schönbrunn in the city of Vienna by playing back con- and hetero-specific alarm calls and control stimuli (great tit song and no stimuli) at predator (wolf, polar bear) and non-predator (eland antelope and cranes, peccaries) enclosures. We recorded responses of crows as the percentage of birds flying away after hearing the playback (out of those present before the playback) and as the number of vocalizations given by the present birds. A significantly higher percentage of crows flew away after hearing either con- or hetero-specific alarm calls, but it did not significantly differ between the predator and the non-predator context. Crows treated jackdaw calls just as crow calls, indicating that they make proper use of hetero-specific alarm calls. Responding similarly in both contexts may suggest that the crows were uncertain about the threat a particular zoo animal represents and were generally cautious. In the predator context, however, a high percentage of crows also flew away upon hearing the great tit control song which suggests that they may still evaluate those species which occasionally killed crows as more dangerous and respond to any conspicuous sound.     

The temporal organization of functional brain connectivity is abnormal in schizophrenia but does not correlate with symptomatology

Previous work employing graph theory and nonlinear analysis has found increased spatial and temporal disorder, respectively, of functional brain connectivity in schizophrenia. We present a new method combining graph theory and nonlinear techniques that measures the temporal disorder of functional brain connections. Multichannel electroencephalographic data were windowed and functional networks were reconstructed using the minimum spanning trees of correlation matrices. Using a method based on Shannon entropy, we found elevated connection entropy in gamma activity of patients with schizophrenia; however, gamma connection entropy remained elevated in patients with schizophrenia even after a reduction in symptoms due to treatment with antipsychotics. Our results are consistent with several possibilities: (1) aberrant functional connectivity is epiphenomenal to schizophrenia, (2) aberrant functional connectivity is a central feature but antipsychotics reduce symptoms by an independent mechanism, or (3) connection entropy is not an appropriately sensitive measure of brain abnormalities in schizophrenia.     

Functional lateralization of the human premotor cortex during sequential movements

A neurological truism is that each side of the brain controls movements on the opposite side of the body. Yet some left hemisphere brain lesions cause bilateral impairment of complex motor function and/or ideomotor apraxia. We report that the left dorsal premotor cortex of normal right-handed people plays a fundamental role in sequential movement of both right and left hands. Subjects performed sequential finger movements during functional magnetic resonance imaging of the motor cortices. In right-handed subjects, the volume of activated dorsal premotor cortex showed a left hemispheric predominance during hand movements. We suggest that the observed left premotor dominance contributes to the lateralization found in lesion studies.