Respiratory rhythms in stingless bee workers: circadian and ultradian components throughout adult development

The workers of the stingless bee, Melipona quadrifasciata, assume different tasks during their adult life. Newly emerged individuals remain inside the nest, without contact with the external environment. Maturing workers go to more peripheral regions and only the oldest, the foragers, leave the nest. As this diversity of activities implies different metabolic patterns, oxygen consumption has been measured in workers of three different ages: 24-48 h (nurses), 10-15 days (builders), and older than 25 days (foragers). Oxygen consumption of individually isolated workers was determined by intermittent respirometry, under constant darkness and temperature of 25 +/- 1 degrees C. Sets of 24-h measurements were obtained from individuals belonging to each of the three worker groups. Rhythmicity has been assessed in the daily (24 h) and ultradian (5-14 h) domains. This experimental design allowed detection of endogenous rhythms without the influence of the social group and without inflicting stress on the individuals, as would be caused by their longer isolation from the colony. Significant 24-h rhythms in oxygen consumption were present in nurses, builders and foragers; therefore, workers are rhythmic from the age of 24-48 h. However, the amplitude of the circadian rhythm changed according to age: nurses showed the lowest values, while foragers consistently presented the largest ones, about ten times larger than the amplitude of nurses` respiratory rhythm. Ultradian frequencies were detected for all worker groups, the power and frequencies of which varied little with age. This means that the ultradian strength was relatively larger in nurses and apparently maintains some relationship with the queen`s oviposition episodes.

A idéia de corpo e a configuração do ambiente da improvisação musical

O objetivo deste texto é evidenciar a importância da ideia de corpo para a reflexão sobre o ambiente da improvisação musical. Este tipo de prática em tempo real que parte de uma relação direta dos músicos com os seus instrumentos sem a mediação de uma partitura tem como ponto de partida inevitável o corpo dos improvisadores envolvidos. O corpo funciona tanto como um fator de reprodução de possíveis – refletindo os limites do próprio corpo (repetição) - quanto como um potencializador de produção de virtualidades – fundamentados numa expansão destes limites (diferença). Trata-se então de examinar, no agenciamento da improvisação, como o corpo pode ser entendido como detentor deste duplo dinamismo e, neste contexto, que tipo de relacionamento pode estabelecer com a matéria sonora. Procuraremos também estabelecer o papel das ideias de desejo e prazer na configuração deste dinamismo e relacionar esta reflexão com as propostas de improvisação livre e idiomática. Para esta discussão serão utilizados alguns conceitos formulados por Gilles Deleuze como território e linha de fuga, as reflexões de Paul Zumthor sobre corpo, oralidade e performance e as discussões epistemológicas de Edgar Morin sobre o conhecimento e a cultura

Consevatório Drámatico e Musical de São Paulo: a primeira escola de teatro do Brasil

This article studies the Drama and Music Conservatory of São Paulo as an acting school since its foundation in 1906. Although the institution is currently dedicated exclusively to music education, we need to remember that it was the first drama school in South America and represented an important aspect of the growth and modernization of theater in Sao Paulo in the early 1900s. It is on this latter aspect that this study focuses on as it provides background information and examines the role of the institution in the context of São Paulo and Brazilian theater of that period. The essay attempts to understand the artistic orientation of the acting program (until the 1940s when the course was eliminated) and to evaluate its merits and shortcomings throughout the years

Forced Desynchronization of Activity Rhythms in a Model of Chronic Jet Lag in Mice

We studied locomotor activity rhythms of C57/Bl6 mice under a chronic jet lag (CJL) protocol (ChrA(6/2)), which consisted of 6-hour phase advances of the light-dark schedule (LD) every 2 days. Through periodogram analysis, we found 2 components of the activity rhythm: a short-period component (21.01 +/- 0.04 h) that was entrained by the LD schedule and a long-period component (24.68 +/- 0.26 h). We developed a mathematical model comprising 2 coupled circadian oscillators that was tested experimentally with different CJL schedules. Our simulations suggested that under CJL, the system behaves as if it were under a zeitgeber with a period determined by (24 -[phase shift size/days between shifts]). Desynchronization within the system arises according to whether this effective zeitgeber is inside or outside the range of entrainment of the oscillators. In this sense, ChrA(6/2) is interpreted as a (24 - 6/2 = 21 h) zeitgeber, and simulations predicted the behavior of mice under other CJL schedules with an effective 21-hour zeitgeber. Animals studied under an asymmetric T = 21 h zeitgeber (carried out by a 3-hour shortening of every dark phase) showed 2 activity components as observed under ChrA(6/2): an entrained short-period (21.01 +/- 0.03 h) and a long-period component (23.93 +/- 0.31 h). Internal desynchronization was lost when mice were subjected to 9-hour advances every 3 days, a possibility also contemplated by the simulations. Simulations also predicted that desynchronization should be less prevalent under delaying than under advancing CJL. Indeed, most mice subjected to 6-hour delay shifts every 2 days (an effective 27-hour zeitgeber) displayed a single entrained activity component (26.92 +/- 0.11 h). Our results demonstrate that the disruption provoked by CJL schedules is not dependent on the phase-shift magnitude or the frequency of the shifts separately but on the combination of both, through its ratio and additionally on their absolute values. In this study, we present a novel model of forced desynchronization in mice under a specific CJL schedule; in addition, our model provides theoretical tools for the evaluation of circadian disruption under CJL conditions that are currently used in circadian research.

External temporal organization in biological rhythms

This paper is intended as a proposition of a new concept in the field of chronobiology, External Temporal Organization, a notion complementary to that of the Internal Temporal Organization. We will try to explain the possibility that a set of external elements, that occur in a particular order, can act together as a single synchronizing element of the circadian system. We will see that this is not a zeitgeber, in the classic sense, but a much more complex factor, consisting of several elements that appear in the real environment at different times ( phases), constituting as a whole a powerful temporal frame, closer to the way the stimuli occur in the natural environment, in which the entrainment does not take place just in a specific time of the day.

Modeling the Emergence of Circadian Rhythms in a Clock Neuron Network

Circadian rhythms in pacemaker cells persist for weeks in constant darkness, while in other types of cells the molecular oscillations that underlie circadian rhythms damp rapidly under the same conditions. Although much progress has been made in understanding the biochemical and cellular basis of circadian rhythms, the mechanisms leading to damped or self-sustained oscillations remain largely unknown. There exist many mathematical models that reproduce the circadian rhythms in the case of a single cell of the Drosophila fly. However, not much is known about the mechanisms leading to coherent circadian oscillation in clock neuron networks. In this work we have implemented a model for a network of interacting clock neurons to describe the emergence (or damping) of circadian rhythms in Drosophila fly, in the absence of zeitgebers. Our model consists of an array of pacemakers that interact through the modulation of some parameters by a network feedback. The individual pacemakers are described by a well-known biochemical model for circadian oscillation, to which we have added degradation of PER protein by light and multiplicative noise. The network feedback is the PER protein level averaged over the whole network. In particular, we have investigated the effect of modulation of the parameters associated with (i) the control of net entrance of PER into the nucleus and (ii) the non-photic degradation of PER. Our results indicate that the modulation of PER entrance into the nucleus allows the synchronization of clock neurons, leading to coherent circadian oscillations under constant dark condition. On the other hand, the modulation of non-photic degradation cannot reset the phases of individual clocks subjected to intrinsic biochemical noise.

Daily rhythms of native Brazilians in summer and winter

Access to electricity, granting relative independence of human activity on the dark phase of the day, has been pointed out as an important cause for the absence of seasonal changes in the daily rhythms of humans living in urban areas. Featuring a population of adult Guarani natives living without access to electricity, the present naturalistic study was designed to explore possible effects of different natural photoperiods and temperature on human circadian rhythms. We compared time series of wrist temperature (WT) and motor activity in winter and summer, respectively, 01 24 individuals aged 18 to 80. Twenty-four-hour rhythms of WT showed lower amplitudes and higher mean levels in summer, with no significant seasonal differences in acrophase. In contrast, rest-activity (RA) rhythms exhibited a significantly later rest on-and offset in summer, but no seasonal changes in duration, amplitude and mean level. We furthermore identified a phase advance of both the WT acrophase and rest onset with increasing age of the individuals. We concluded that in our study the effect of different seasons was reflected in the amplitude and mean level of the WT rhythm, as well the onset of nighttime rest, which was delayed in summer. (C) 2011 Elsevier Inc. All rights reserved.

Emoções de uma escuta musical afetam a percepção subjetiva de tempo

Este estudo verificou se emoções percebidas durante uma escuta musical influenciam a percepção temporal. Músicos e não músicos foram submetidos a tarefas de escuta de trechos musicais do repertório erudito ocidental com 20 segundos de duração cada um e tarefas de associação temporal de cada trecho ouvido a durações padrões, que variavam de 16 a 24 segundos. Os trechos musicais empregados eram representativos de uma dentre as categorias emocionais Alegria, Tristeza, Serenidade ou Medo / Raiva. Uma análise de variância mostrou que, enquanto os não músicos apresentaram subestimações temporais associadas a pelo menos um trecho musical de cada uma das categorias emocionais, os músicos subestimaram todos os trechos musicais tristes, relacionados às características de baixo arousal e valência afetiva negativa.

Previous exposure to musical auditory stimulation immediately influences the cardiac autonomic responses to the postural change maneuver in women

Background Chronic exposure to musical auditory stimulation has been reported to improve cardiac autonomic regulation. However, it is not clear if music acutely influences it in response to autonomic tests. We evaluated the acute effects of music on heart rate variability (HRV) responses to the postural change maneuver (PCM) in women. Method We evaluated 12 healthy women between 18 and 28 years old and HRV was analyzed in the time (SDNN, RMSSD, NN50 and pNN50) and frequency (LF, HF and LF/HF ratio) domains. In the control protocol, the women remained at seated rest for 10 minutes and quickly stood up within three seconds and remained standing still for 15 minutes. In the music protocol, the women remained at seated rest for 10 minutes, were exposed to music for 10 minutes and quickly stood up within three seconds and remained standing still for 15 minutes. HRV was recorded at the following time: rest, music (music protocol) 0–5, 5–10 and 10–15 min during standing. Results In the control protocol the SDNN, RMSSD and pNN50 indexes were reduced at 10–15 minutes after the volunteers stood up, while the LF (nu) index was increased at the same moment compared to seated rest. In the protocol with music, the indexes were not different from control but the RMSSD, pNN50 and LF (nu) were different from the music period. Conclusion Musical auditory stimulation attenuates the cardiac autonomic responses to the PCM.

Emoções de uma escuta musical afetam a percepção subjetiva de tempo

Este estudo verificou se emoções percebidas durante uma escuta musical influenciam a percepção temporal. Músicos e não músicos foram submetidos a tarefas de escuta de trechos musicais do repertório erudito ocidental com 20 segundos de duração cada um e tarefas de associação temporal de cada trecho ouvido a durações padrões, que variavam de 16 a 24 segundos. Os trechos musicais empregados eram representativos de uma dentre as categorias emocionais Alegria, Tristeza, Serenidade ou Medo / Raiva. Uma análise de variância mostrou que, enquanto os não músicos apresentaram subestimações temporais associadas a pelo menos um trecho musical de cada uma das categorias emocionais, os músicos subestimaram todos os trechos musicais tristes, relacionados às características de baixo arousal e valência afetiva negativa.

A livre improvisação musical e a filosofia de Gilles Deleuze

Nos últimos anos a improvisação passou a figurar como um tema cada vez mais presente nos ambientes acadêmicos e hoje é considerada uma importante linha de pesquisa. A nossa reflexão sobre a livre improvisação, além de se apoiar em nossas experiências práticas, tem como uma das suas principais referências a obra do filósofo francês Gilles Deleuze de quem são emprestados conceitos fundamentais tais como, estratificação, território, plano de consistência, molaridade e molecularidade, corpo sem órgãos, ritmo, meios e ritornelo. Neste artigo, originalmente publicado no número 49, vol. 1 da revista Perspectives of New Music, trataremos de mostrar de que forma estes conceitos nos auxiliam a pensar e fundamentar a livre improvisação musical conforme a concebemos em nossos trabalhos práticos e teóricos.

Disruption of endogenous tidal rhythms of larval release linked to food supply and heat stress in an intertidal barnacle

The timing of larval release may greatly affect the survivorship and distribution of pelagic stages and reveal important aspects of life history tactics in marine invertebrates. Endogenous rhythms of breeding individuals and populations are valuable indicators of selected strategies because they are free of the neutral effect of stochastic environmental variation. The high-shore intertidal barnacle Chthamalus bisinuatus exhibits endogenous tidal and tidal amplitude rhythms in a way that larval release would more likely occur during fortnightly neap periods at high tide. Such timing would minimize larval loss due to stranding and promote larval retention close to shore. This fully explains temporal patterns in populations facing the open sea and inhabiting eutrophic areas. However, rhythmic activity breaks down to an irregular pattern in a population within the São Sebastião Channel subjected to large variation of food supply around a mesotrophic average. Peaks of chl a concentration precede release events by 6 d, suggesting resource limitation for egg production within the channel. Also, extreme daily temperatures imposing mortality risk correlate to release rate just 1 d ahead, suggesting a terminal reproductive strategy. Oceanographic conditions apparently dictate whether barnacles follow a rhythmic trend of larval release supported by endogenous timing or, alternatively, respond to the stochastic variation of key environmental factors, resulting in an erratic temporal pattern.