A note on the KP hierarchy

Given the two boson representation of the conformal algebra \hat W_\infty, the second Hamiltonian structure of the KP hierarchy, I construct a bi-Hamiltonian hierarchy for the two associated currents. The KP hierarchy appears as a composite of this new and simpler system. The bi-Hamiltonian structure of the new hierarchy gives naturally all the Hamiltonian structures of the KP system.Comment: 12 pages, no figure

On the classical WN(l)W_N^{(l)} algebras

We analyze the W_N^l algebras according to their conjectured realization as the second Hamiltonian structure of the integrable hierarchy resulting from the interchange of x and t in the l^{th} flow of the sl(N) KdV hierarchy. The W_4^3 algebra is derived explicitly along these lines, thus providing further support for the conjecture. This algebra is found to be equivalent to that obtained by the method of Hamiltonian reduction. Furthermore, its twisted version reproduces the algebra associated to a certain non-principal embedding of sl(2) into sl(4), or equivalently, the u(2) quasi-superconformal algebra. The general aspects of the W_N^l algebras are also presented.Comment: 28 page

Stimulus-invariant processing and spectrotemporal reverse correlation in primary auditory cortex

The spectrotemporal receptive field (STRF) provides a versatile and integrated, spectral and temporal, functional characterization of single cells in primary auditory cortex (AI). In this paper, we explore the origin of, and relationship between, different ways of measuring and analyzing an STRF. We demonstrate that STRFs measured using a spectrotemporally diverse array of broadband stimuli -- such as dynamic ripples, spectrotemporally white noise, and temporally orthogonal ripple combinations (TORCs) -- are very similar, confirming earlier findings that the STRF is a robust linear descriptor of the cell. We also present a new deterministic analysis framework that employs the Fourier series to describe the spectrotemporal modulations contained in the stimuli and responses. Additional insights into the STRF measurements, including the nature and interpretation of measurement errors, is presented using the Fourier transform, coupled to singular-value decomposition (SVD), and variability analyses including bootstrap. The results promote the utility of the STRF as a core functional descriptor of neurons in AI.Comment: 42 pages, 8 Figures; to appear in Journal of Computational Neuroscienc

Toda and Volterra Lattice Equations from Discrete Symmetries of KP Hierarchies

The discrete models of the Toda and Volterra chains are being constructed out of the continuum two-boson KP hierarchies. The main tool is the discrete symmetry preserving the Hamiltonian structure of the continuum models. The two-boson currents of KP hierarchy are being associated with sites of the corresponding chain by successive actions of discrete symmetry.Comment: 12 pgs, LaTeX, IFT-P.041/9

Stimulus-invariant processing and spectrotemporal reverse correlation in primary auditory cortex

The spectrotemporal receptive field (STRF) provides a versatile and integrated, spectral and temporal, functional characterization of single cells in primary auditory cortex (AI). In this paper, we explore the origin of, and relationship between, different ways of measuring and analyzing an STRF. We demonstrate that STRFs measured using a spectrotemporally diverse array of broadband stimuli—such as dynamic ripples, spectrotemporally white noise, and temporally orthogonal ripple combinations (TORCs)—are very similar, confirming earlier findings that the STRF is a robust linear descriptor of the cell. We also present a new deterministic analysis framework that employs the Fourier series to describe the spectrotemporal modulations contained in the stimuli and responses. Additional insights into the STRF measurements, including the nature and interpretation of measurement errors, is presented using the Fourier transform, coupled to singular-value decomposition (SVD), and variability analyses including bootstrap. The results promote the utility of the STRF as a core functional descriptor of neurons in A

Stressors in anaesthesiology: development and validation of a new questionnaire: A cross-sectional study of Portuguese anaesthesiologists

BACKGROUND: Stress in anaesthesiologists is a common and multifactorial problem related to patients, colleagues and organisations. The consequences of stress include depression, work-home conflicts and burnout. Reduction in stress can be achieved by reducing the number and magnitude of stressors or by increasing resilience strategies. OBJECTIVES: We have created the self-reporting 'Stress Questionnaire in Anaesthesiologists' (SQA), to qualify the sources of stress in anaesthesiologists' professional lives, and measure the level of associated stress. Our study aimed to develop and validate the SQA using exploratory and confirmatory factor analyses. Construct validity was assessed through correlations between SQA and negative psychological outcomes as well as by comparing perception of stress among different known groups. DESIGN: A questionnaire-based cross-sectional, correlational, observational study. SETTINGS: The study was conducted between January 2014 and December 2014, throughout different anaesthesia departments in Portuguese hospitals. Data collection was from a representative subset at one specific time point. PARTICIPANTS: A sample of 710 anaesthesia specialists and residents from Portugal. MAIN OUTCOME MEASURES: The primary outcome measure was to identify specific stressors in anaesthesiologists. Secondary outcome was the association between stressors and burnout, depression symptoms, anxiety, stress, rumination, satisfaction with life and functional impairment. RESULTS: The exploratory analysis showed the SQA is a tri-dimensional instrument and confirmatory analysis showed the tri-dimensional structure presented good model fit. The three dimensions of SQA correlated positively with other stress measures and burnout, but negatively with satisfaction with life. CONCLUSION: SQA is a well adjusted measure for assessing stressors in anaesthesia physicians and includes clinical, organisational and team stress factors. Results showed that the SQA is a robust and reliable instrument.info:eu-repo/semantics/publishedVersio