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IntroductionThe binocular system provides a stereoscopic view from slightly different retinal images and produces perceptual alternations, namely, binocular rivalry, from significantly different retinal images. When we observe a stereogram in which the stimulus configurations induce stereopsis and rivalry simultaneously, the binocular system prefers stereopsis to rivalry. However, changes in visual perception are yet to be investigated by parametrically manipulating the components of a stereogram.MethodsWe examined stereopsis preferences in stereograms with various horizontal disparities. The stereograms of our paradigms included horizontal and vertical bars in one eye and a vertical bar alone in the other. Under experimental conditions, the vertical bar superimposed on the horizontal bar varied its position relative to the opposite vertical bar: range of horizontal disparity, 0.0′ to 42.3′. The superimposed vertical bar was absent under the control condition. Observers were instructed to indicate the disappearance of monocular horizontal bars, that is, targets, from their perception during the 30-s trials.ResultsThe total disappearance duration decreased under experimental conditions compared with that under control conditions, and it gradually increased with an increase in the disparity of the stereoscopic vertical bars.DiscussionThese results indicate that the disparity in the stereoscopic components biases binocular perception away from the rivalry between the vertical and horizontal bars toward the stereopsis of the vertical bars. Furthermore, the disappearance duration showed a unimodal and asymmetric distribution across all disparity conditions. This suggests that rivalry processing occurs in parallel when stereopsis is dominant. We found that stereopsis preference is an outcome of binocular perception selection biased by disparity.

Abstract We experimentally demonstrate resonance of first-order vector vortex beams (VVB) with a triangular optical cavity. We also show that, due to their symmetry properties, the VVBs commonly known as radial and azimuthal beams do not resonate at the same cavity length, which could be explored to use the triangular resonator as a mode sorter. In addition, an intracavity Pancharatnam phase shifter (PPS) is implemented in order to compensate for any birefringent phase that the cavity mirrors may introduce.

Abstract Time perception is inherently subjective and malleable. We experience a wide range of time scales, from less than a second to decades. In addition, our perception of time can be affected by our attentional and emotional states. Previous psychological and neuroimaging studies have used several paradigms and methods to probe factors that influence time perception. Considering these factors facilitates approaches to improve time management and to enhance sensory experiences. This Collection of time perception studies includes reports that focus on stimulus property, physiological state, cross-modal interaction, attention, learning, age, and environment. These findings help to illuminate the complex mechanisms of time perception.

Abstract The ability to parse sound mixtures into coherent auditory objects is fundamental to cognitive functions, such as speech comprehension and language acquisition. Yet, we still lack a clear understanding of how auditory objects are formed. To address this question, we studied a speech-specific case of perceptual multistability, called verbal transformations (VTs), in which a variety of verbal forms is induced by continuous repetition of a physically unchanging word. Here, we investigated the degree to which auditory memory through sensory adaptation influences VTs. Specifically, we hypothesized that when memory persistence is longer, participants are able to retain the current verbal form longer, resulting in sensory adaptation, which in turn, affects auditory perception. Participants performed VT and auditory memory tasks on different days. In the VT task, Japanese participants continuously reported their perception while listening to a Japanese word (2- or 3-mora in length) played repeatedly for 5 min. In the auditory memory task, a different sequence of three morae, e.g., /ka/, /hi/, and /su/, was presented to each ear simultaneously. After some period (0–4 s), participants were visually cued to recall one of the sequences, i.e., in the left or right ear. We found that delayed recall accuracy was negatively correlated with the number of VTs, particularly under 2-mora conditions. This suggests that memory persistence is important for formation and selection of perceptual objects.

Nonreciprocal charge transport in solids, where resistance is different between rightward and leftward currents, is a key function of rectifying devices in modern electronics, as exemplified by p-n semiconductor junctions. Recently, this was also demonstrated in noncentrosymmetric materials in magnetic fields since their band structure exhibits spin polarization coupled to the position of momentum space due to antisymmetric spin-orbit coupling. To enhance the magnitude of the nonreciprocal effect, it is essential to tune such spin-momentum coupling, which has been hampered in conventional materials owing to the difficulty in controlling the broken inversion symmetry built into the lattice and interfacial structures. Here, we report large nonreciprocal resistivity in the layered polar metal BaMnX_{2} (X=Sb, Bi), where the spin-polarized Dirac dispersion depends on the in-plane polarization tunable by chemical substitution of the X site. For X=Sb with a pair of single-type valleys, the nonreciprocal resistivity increases monotonically with decreasing temperature, while for X=Bi with multiple types of valleys it is reduced by about an order of magnitude and exhibits a peak at a low temperature. Theoretical calculations indicate that the nonreciprocal resistivity is sensitive not only to the spin-momentum (spin-valley) coupling but also to the Fermi energy and the Dirac dispersion. The observed significant variation of nonreciprocal transport in the same series of materials might be of great use in the design of junction-free rectifying devices and circuits.

BackgroundDecision-making under risk is a common challenge. It is known that risk-taking behavior varies between contexts of reward and punishment, yet the mechanisms underlying this asymmetry in risk sensitivity remain unclear.MethodsThis study used a monetary task to investigate neurochemical mechanisms and brain dynamics underpinning risk sensitivity. Twenty-eight participants engaged in a task requiring selection of visual stimuli to maximize monetary gains and minimize monetary losses. We modeled participant trial-and-error processes using reinforcement learning.ResultsParticipants with higher subjective utility parameters showed risk preference in the gain domain (r = −0.59) and risk avoidance in the loss domain (r = −0.77). Magnetic resonance spectroscopy (MRS) revealed that risk avoidance in the loss domain was associated with γ-aminobutyric acid (GABA) levels in the ventral striatum (r = −0.42), but not in the insula (r = −0.15). Using functional magnetic resonance imaging (fMRI), we tested whether risk-sensitive brain dynamics contribute to participant risky choices. Energy landscape analyses demonstrated that higher switching rates between brain states, including the striatum and insula, were correlated with risk avoidance in the loss domain (r = −0.59), a relationship not observed in the gain domain (r = −0.02).ConclusionsThese findings from MRS and fMRI suggest that distinct mechanisms are involved in gain/loss decision making, mediated by subcortical neurometabolite levels and brain dynamic transitions.

Abstract The forward η mesons production has been observed by the Large Hadron Collider forward (LHCf) experiment in proton-proton collision at s $$ \sqrt{s} $$ = 13 TeV. This paper presents the measurement of the inclusive production rate of η in p T < 1.1 GeV/c, expressed as a function of the Feynman-x variable. These results are compared with the predictions of several hadronic interaction models commonly used for the modelling of the air showers produced by ultra-high energy cosmic rays. This is both the first measurement of η mesons from LHCf and the first time a particle containing strange quarks has been observed in the forward region for high-energy collisions. These results will provide a powerful constraint on hadronic interaction models for the purpose of improving the understanding of the processes underlying the air showers produced in the Earth’s atmosphere by ultra-energetic cosmic rays.

Abstract El Niño/Southern Oscillation (ENSO) is the main climate mode that drives the interannual variability in climate and consequently vegetation greenness. While widespread green‐up has been reported and examined in tropical America during El Niño, it remains unclear how vegetation in tropical Asia changes during the period. Here, we used four remote sensing‐based leaf area index (LAI) products to investigate changes in vegetation greenness during the 2015/16 El Niño in tropical Asia. We found a strong green‐up during the 2015/16 El Niño in tropical Asia, with its regional average LAI stronger than that of tropical America. The drivers for the green‐up vary across the region, with radiation being the main driver for continental tropical Asia, and temperature and soil water anomalies in the west and east parts of maritime tropical Asia, respectively. These findings provide important insights into the response of tropical Asia's vegetation to extreme climate anomalies.

Global and regional sources and sinks of carbon across the earth's surface have been studied extensively using atmospheric carbon dioxide (CO2) observations and atmospheric chemistry-transport model (ACTM) simulations (top-down/inversion method). However, the uncertainties in the regional flux distributions remain unconstrained due to the lack of high-quality measurements, uncertainties in model simulations, and representation of data and flux errors in the inversion systems. Here, we assess the representation of data and flux errors using a suite of 16 inversion cases derived from a single transport model (MIROC4-ACTM) but different sets of a priori (bottom-up) terrestrial biosphere and oceanic fluxes, as well as prior flux and observational data uncertainties (50 sites) to estimate CO2 fluxes for 84 regions over the period 2000–2020. The inversion ensembles provide a mean flux field that is consistent with the global CO2 growth rate, land and ocean sink partitioning of −2.9 ± 0.3 (± 1σ uncertainty on the ensemble mean) and −1.6 ± 0.2 PgC yr−1, respectively, for the period 2011–2020 (without riverine export correction), offsetting about 22 %–33 % and 16 %–18 % of global fossil fuel CO2 emissions. The rivers carry about 0.6 PgC yr−1 of land sink into the deep ocean, and thus the effective land and ocean partitioning is −2.3 ± 0.3 and −2.2 ± 0.3, respectively. Aggregated fluxes for 15 land regions compare reasonably well with the best estimations for the 2000s (∼ 2000–2009), given by the REgional Carbon Cycle Assessment and Processes (RECCAP), and all regions appeared as a carbon sink over 2011–2020. Interannual variability and seasonal cycle in CO2 fluxes are more consistently derived for two distinct prior fluxes when a greater degree of freedom (increased prior flux uncertainty) is given to the inversion system. We have further evaluated the inversion fluxes using meridional CO2 distributions from independent (not used in the inversions) aircraft and surface measurements, suggesting that the ensemble mean flux (model–observation mean ± 1σ standard deviation = −0.3 ± 3 ppm) is best suited for global and regional CO2 flux budgets than an individual inversion (model–observation 1σ standard deviation = −0.35 ± 3.3 ppm). Using the ensemble mean fluxes and uncertainties for 15 land and 11 ocean regions at 5-year intervals, we show promise in the capability to track flux changes toward supporting the ongoing and future CO2 emission mitigation policies.

Understanding the structural origin of the anomalous properties of SiO2 liquid and glass at high pressures is fundamental in wide range of scientific fields. Here, the authors find experimental evidence of a bimodal behavior in the translational order of silicon’s second shell and breaking of local tetrahedral symmetry in SiO2 glass under pressure.

Regional land carbon budgets provide insights into the spatial distribution of the land uptake of atmospheric carbon dioxide and can be used to evaluate carbon cycle models and to define baselines for land-based additional mitigation efforts. The scientific community has been involved in providing observation-based estimates of regional carbon budgets either by downscaling atmospheric CO2 observations into surface fluxes with atmospheric inversions, by using inventories of carbon stock changes in terrestrial ecosystems, by upscaling local field observations such as flux towers with gridded climate and remote sensing fields, or by integrating data-driven or process-oriented terrestrial carbon cycle models. The first coordinated attempt to collect regional carbon budgets for nine regions covering the entire globe in the RECCAP-1 project has delivered estimates for the decade 2000–2009, but these budgets were not comparable between regions due to different definitions and component fluxes being reported or omitted. The recent recognition of lateral fluxes of carbon by human activities and rivers that connect CO2 uptake in one area with its release in another also requires better definitions and protocols to reach harmonized regional budgets that can be summed up to a globe scale and compared with the atmospheric CO2 growth rate and inversion results. In this study, using the international initiative RECCAP-2 coordinated by the Global Carbon Project, which aims to be an update to regional carbon budgets over the last 2 decades based on observations for 10 regions covering the globe with a better harmonization than the precursor project, we provide recommendations for using atmospheric inversion results to match bottom-up carbon accounting and models, and we define the different component fluxes of the net land atmosphere carbon exchange that should be reported by each research group in charge of each region. Special attention is given to lateral fluxes, inland water fluxes, and land use fluxes.

Background: As populations age and pandemics continue, grief disrupts the health and productivity of increasingly bereaved populations. While funerals can reconnect old friends and relations to provide psycho-social support, and satisfying funeral participation reportedly reduces such psychiatric complications of grief, the psychological effects of recent restrictions on funerals remains unclear. This first English report of open-ended responses to a Japan-wide survey sheds some light on this by looking at Japanese psychological reflections on their funerals. Objectives: To determine what aspects of funerals the Japanese bereaved feel psycho-socially valuable or conversely problematic, and for what reasons. Setting: Data were collected using anonymized all-Japan postal surveys from 2019 to 2020. Participants: 288 recently-bereaved chief mourners submitted 353 open-ended responses discussing their experiences and feelings about the funerals they conducted. Method: Anonymized data were divided into positive, regrets, vacillations, and negative comments about the subjects most frequently cited. Results: Most commonly cited were funeral directors (64), attendees (56), ritual/ceremony (49), and the need for (pre-)planning (40). Respondents profoundly appreciated funeral directors' support, and regretted not having planned better or invited more people to the funeral. Dissatisfaction tended to focus on unexplained expenses and mistakes or offenses in rituals. Many also criticized their doctors for not realistically forecasting their loved ones' demise. Conclusions: Responses validated that responsive funeral directors can significantly support their clients through early acute grief, and that inviting more celebrants to a full funeral facilitates psycho-social support and may obviate future regrets. Rituals too provide memorable means to help survivors deal with grief. Medical professionals should psychologically encourage terminal patients' families to communicate while patients are still coherent; families are strongly advised to discuss funeral plans with their elders before the end of life.

Autonomous sensory meridian response (ASMR) is a complex sensory-emotional experience characterized by pleasant tingling sensations initiating at the scalp. ASMR is triggered in some people (called ASMR-responders) by stimuli including whispering, personal attention, and crisp sounds (termed ASMR triggers). Since its inception, ASMR has been likened to synesthesia, but convincing empirical data directly linking ASMR with synesthesia is lacking. In this study, we examined whether the prevalence of synesthesia is indeed significantly higher in ASMR-responders than non-responders. A sample of working adults and students (N = 648) were surveyed about their experience with ASMR and common types of synesthesia. The proportion of synesthetes who were classified as ASMR-responders was 52%, whereas 22% of ASMR-responders were also synesthetes. These results suggest that: (1) over half of those identifying as synesthetes also experience ASMR, and (2) that synesthesia is up to four times as common among ASMR-responders as among non-responders (22% vs. 5%). Findings also suggest a prevalence rate for ASMR of approximately 20%. Overall, the co-occurrence of ASMR and synesthesia lends empirical support to the idea that ASMR may be driven by synesthetic mechanisms, but future research would benefit from examining how ASMR and synesthesia are different, as well as similar.

Achievement of task performance is required to maintain a constant level of attention. Attentional level fluctuates over the course of daily activities. However, brain dynamics leading to attentional fluctuation are still unknown. We investigated the underlying mechanisms of sustained attention using functional magnetic resonance imaging (fMRI). Participants were scanned with fMRI while performing an auditory, gradual-onset, continuous performance task (gradCPT). In this task, narrations gradually changed from one to the next. Participants pressed a button for frequent Go trials (i.e., male voices) as quickly as possible and withheld responses to infrequent No-go trials (i.e., female voices). Event-related analysis revealed that frontal and temporal areas, including the auditory cortex, were activated during successful and unsuccessful inhibition of predominant responses. Reaction-time (RT) variability throughout the auditory gradCPT was positively correlated with signal changes in regions of the dorsal attention network: superior frontal gyrus and superior parietal lobule. Energy landscape analysis showed that task-related activations could be clustered into different attractors: regions of the dorsal attention network and default mode network. The number of alternations between RT-stable and erratic periods increased with an increase in transitions between attractors in the brain. Therefore, we conclude that dynamic transitions between brain states are closely linked to auditory attentional fluctuations.

Abstract Background The activation of melanocortin 1 receptor (MC1R) on melanocytes stimulates the production of eumelanin. A tridecapeptide α melanocyte‐stimulating hormone (αMSH) is known to induce skin pigmentation. Objectives We characterised the properties of a novel oral MC1R agonist dersimelagon (MT‐7117) with respect to its specific binding to MC1R, downstream signalling and eumelanin production in experimental models. Methods The competitive binding and production of intracellular cyclic adenosine 3′, 5′‐monophosphate in cells expressing recombinant melanocortin receptors were examined. A mouse melanoma cell line B16F1 was used for the evaluation of in vitro melanin production. The in vitro activity of MT‐7117 was determined with αMSH and [Nle4, D‐Phe7]‐αMSH (NDP‐αMSH) as reference comparators. The change of coat colour and skin pigmentation were evaluated after repeat administration of MT‐7117 by oral gavage to C57BL/6J‐Ay/+ mice and cynomolgus monkeys, respectively. Results MT‐7117 showed the highest affinity for human MC1R compared to the other melanocortin receptors evaluated and agonistic activity for human, cynomolgus monkey and mouse MC1R, with EC50 values in the nanomolar range. In B16F1 cells, MT‐7117 increased melanin production in a concentration‐dependent manner. In vivo, MT‐7117 (≥0.3 mg/kg/day p.o.) significantly induced coat colour darkening in mice. MT‐7117 (≥1 mg/kg/day p.o.) induced significant skin pigmentation in monkeys and complete reversibility was observed after cessation of its administration. Conclusions MT‐7117 is a novel oral MC1R agonist that induces melanogenesis in vitro and in vivo, suggesting its potential application for the prevention of phototoxic reactions in patients with photodermatoses, such as erythropoietic protoporphyria and X‐linked protoporphyria.

Background: Limited data are available on the management of pregnant women with severe or critical forms of COVID-19, such as the optimal timing of provider-initiated delivery, and post-partum care, including antithrombotic prophylaxis. We present the clinical course, pre- and post-partum management, and outcomes of two pregnant women critically ill with COVID-19. Cases: Both women had confirmed SARS-CoV-2 pneumonia with rapid clinical decompensation that required admission to the intensive care unit, intubation, and delivery by emergency cesarean section at 32 and 29 weeks. Both patients clinically improved in the first two postoperative days, but this was followed by clinical, laboratory and radiological deterioration on the third postoperative day; however, they both improved again after full anticoagulation. This pattern suggests the possible formation of pulmonary microthrombi in the early puerperium. We discuss the challenges faced by the multiprofessional team in the management of these patients. Conclusions: There are few resources to guide health professionals caring for pregnant women with critical COVID-19. These two cases contribute to the rapidly evolving knowledge on the management and outcomes of pregnant women with COVID-19.

The flow behind two flat plates placed normal to the flow in side-by-side arrangement was experimentally investigated by varying the gap ratio G* (the ratio of gap spacing to plate width) in the range of 0.0 ≤ G* ≤ 2.5 to examine the effect of gap ratio on the wake. The flow patterns around the plates were observed using the hydrogen bubble flow visualization in the water tunnel. Velocity and pressure components were acquired by employing hot-wire anemometers and digital manometers in the wind tunnel. From the experiment, it has been found that, at gap ratios less than 1.6, the gap flow was biased either upward or downward and maintained a stable biased flow pattern. The width of the wake on the biased side was increased with the gap ratio, while that on the unbiased side was decreased. At 1.6 ≤ G* < 2.0, the switching of the biased gap flow appeared due to the flow instability by mutual interference of the vortex shedding from the plates, while at G* of 2.0 or more, the gap flow was no longer biased. The plates on the biased side showed relatively low base pressure and high velocity, and detected periodic vortex shedding, while those on the unbiased side showed the opposite phenomena. At gap ratios less than 2.0, two Strouhal numbers indicating the bi-stable situation exist, and the difference between the two Strouhal numbers decreased with the gap ratio.

Auditory frisson is the experience of feeling of cold or shivering related to sound in the absence of a physical cold stimulus. Multiple examples of frisson-inducing sounds have been reported, but the mechanism of auditory frisson remains elusive. Typical frisson-inducing sounds may contain a looming effect, in which a sound appears to approach the listener's peripersonal space. Previous studies on sound in peripersonal space have provided objective measurements of sound-inducing effects, but few have investigated the subjective experience of frisson-inducing sounds. Here we explored whether it is possible to produce subjective feelings of frisson by moving a noise sound (white noise, rolling beads noise, or frictional noise produced by rubbing a plastic bag) stimulus around a listener's head. Our results demonstrated that sound-induced frisson can be experienced stronger when auditory stimuli are rotated around the head (binaural moving sounds) than the one without the rotation (monaural static sounds), regardless of the source of the noise sound. Pearson's correlation analysis showed that several acoustic features of auditory stimuli, such as variance of interaural level difference (ILD), loudness, and sharpness, were correlated with the magnitude of subjective frisson. We had also observed that the subjective feelings of frisson by moving a musical sound had increased comparing with a static musical sound.

The nonlinear interaction between terahertz frequency electric fields and atoms or molecules can be used to study fundamental and technical problems. Here the authors demonstrate a THz–driven phase transition, with a potential application as a THz sensor, using Rydberg atomic states in a cesium vapor.

Abstract Perceptual organisation must select one interpretation from several alternatives to guide behaviour. Computational models suggest that this could be achieved through an interplay between inhibition and excitation across competing types of neural population coding for each interpretation. Here, to test for such models, we used magnetic resonance spectroscopy to measure non-invasively the concentrations of inhibitory γ-aminobutyric acid (GABA) and excitatory glutamate-glutamine (Glx) in several brain regions. Human participants first performed auditory and visual multistability tasks that produced spontaneous switching between percepts. Then, we observed that longer percept durations during behaviour were associated with higher GABA/Glx ratios in the sensory area coding for each modality. When participants were asked to voluntarily modulate their perception, a common factor across modalities emerged: the GABA/Glx ratio in the posterior parietal cortex tended to be positively correlated with the amount of effective volitional control. Our results provide direct evidence implicating that the balance between neural inhibition and excitation within sensory regions resolves perceptual competition. This powerful computational principle appears to be leveraged by both audition and vision, implemented independently across modalities, but modulated by an integrated control process.

This work deals with the degradation of effluent of a potato processing industry from Itajubá (MG) region, which is a processed potato pole. The choice of this effluent is based on the fact that companies in the region are in search of a final destination more suitable for this type of waste which causes damage to fauna and flora. Although not toxic, if this type of effluent is not treated correctly it can contribute to the disappearance of springs, the appearance of unpleasant odors in the rivers and damage to the local fauna and flora. The present study has the purpose to evaluate if the battery ferrite is effective in the treatment of effluent of the potato processing industry. Therefore, different catalysts were used: Fe(NO3)3.9H2O and Ferrite, different H2O2 (15 and 30 mmol L-1) concentrations with and without solar radiation in different treatment times of the potato effluent with pH value adjusted in 2.5. Approximately 32% of mineralization of the effluent organic compounds were reached during the first ten minutes, demonstrating the effectiveness of ferrite as a catalyst in the process, as well as significant changes in the effluent color and elimination of the odor. In addition, the ferrites could be recovered at the end of the process by applying a magnetic field, thus avoiding the release of catalyst in the effluent and allowing its reuse.

This study investigated the effect of phloroglucinol (1,3,5-trihydroxybenzene) supplementation alone on methane production, rumen fermentation profiles, and microbial population structure of mixed in vitro cultures. Treatments included a control group containing a substrate with no supplement, and substrates supplemented with 2, 4, 6, 8, or 10 mmol/L of phloroglucinol. The results revealed that phloroglucinol was able to decrease methane production in a dose-dependent manner. The highest decrease was observed with 8 and 10 mmol/L supplementations. The relative quantity of methanogen was not affected by phloroglucinol, whereas genus Coprococcus was increased with increasing concentrations of phloroglucinol (p

Maple syrup urine disease (MSUD) is an autosomal recessive disease associated with high levels of branched-chain amino acids. Children with MSUD can present severe neurological damage, but liver transplantation (LT) allows the patient to resume a normal diet and avoid further neurological damage. The use of living related donors has been controversial because parents are obligatory heterozygotes. We report a case of a 2-year-old child with MSUD who underwent a living donor LT. The donor was the patient's mother, and his liver was then used as a domino graft. The postoperative course was uneventful in all three subjects. DNA analysis performed after the transplantation (sequencing of the coding regions of BCKDHA, BCKDHB, and DBT genes) showed that the MSUD patient was heterozygous for a pathogenic mutation in the BCKDHB gene. This mutation was not found in his mother, who is an obligatory carrier for MSUD according to the family history and, as expected, presented both normal clinical phenotype and levels of branched-chain amino acids. In conclusion, our data suggest that the use of a related donor in LT for MSUD was effective, and the liver of the MSUD patient was successfully used in domino transplantation. Routine donor genotyping may not be feasible, because the test is not widely available, and, most importantly, the disease is associated with both the presence of allelic and locus heterogeneity. Further studies with this population of patients are required to expand the use of related donors in MSUD.

BACKGROUND: Spinal anesthesia for cesarean delivery may cause severe maternal hypotension and a decrease in cardiac output. Compared to assessment of cardiac output via a pulmonary artery catheter, the FloTrac/Vigileo™ system may offer a less invasive technique. The aim of this study was to evaluate cardiac output and other hemodynamic measurements made using the FloTrac/Vigileo™ system in patients undergoing spinal anesthesia for elective cesarean section. METHODS: A prospective study enrolling 10 healthy pregnant women was performed. Hemodynamic parameters were continuously obtained at 15 main points: admission to surgery (two baseline measurements), after preload, after spinal anesthesia administration and 4 time points thereafter (4, 6, 8 and 10 min after anesthesia), at skin and uterine incision, newborn and placental delivery, oxytocin administration, end of surgery, and recovery from anesthesia. Hemodynamic therapy was guided by mean arterial pressure, and vasopressors were used as appropriate to maintain baseline values. A repeated measures ANOVA was used for data analysis. RESULTS: There was a significant increase in heart rate and a decrease of stroke volume and stroke volume index up to 10 min after spinal anesthesia (P < 0.01). Importantly, stroke volume variation increased immediately after newborn delivery (P < 0.001) and returned to basal values at the end of surgery. Further hemodynamic parameters showed no significant changes over time. DISCUSSION AND CONCLUSIONS: No significant hemodynamic effects, except for heart rate and stroke volume changes, were observed in pregnant women managed with preload and vasopressors when undergoing elective cesarean section and spinal anesthesia.

JUSTIFICATIVA E OBJETIVOS: Adição de clonidina subaracnóidea (±-agonista) prolonga a ação analgésica da combinação sufentanil e bupivacaína isobárica em analgesia combinada para o trabalho de parto ¹. O objetivo deste estudo foi comparar a qualidade de analgesia e a prevalência de efeitos colaterais após a adição de clonidina subaracnóidea à solução anestésica em gestantes durante trabalho de parto. MÉTODO: Após aprovação da Comissão de Ética, 22 gestantes em trabalho de parto receberam aleatoriamente no espaço subaracnóideo 2,5 mg de bupivacaína hiperbárica 0,5% (grupo CLON/HIPER; n = 11) ou 2,5 mg de bupivacaína isobárica 0,5% (grupo CLON/ISO; n = 11) em associação ao sufentanil 2,5 µg e à clonidina 30 µg. A dor avaliada pela Escala Analógica Visual, a freqüência cardíaca e a pressão arterial média foram estudadas a cada 5 minutos nos primeiros 15 minutos e, a seguir, a cada 15 minutos até o nascimento. Foi avaliada a prevalência de efeitos colaterais (náusea, vômito, prurido e sedação). O estudo foi encerrado no momento em que foi necessária complementação analgésica peridural (dor > 3 cm) ou ao nascimento. A análise estatística foi realizada pelos testes t de Student, Qui-quadrado, Fisher e ANOVA de duas vias para medidas repetidas, considerando como significativo p < 0,05. RESULTADOS: Os grupos CLON/HIPER e CLON/ISO foram semelhantes com relação a dados antropométricos, duração da analgesia (70,9 ± 32,9 vs. 85,4 ± 39,5), freqüência cardíaca, ocorrência de prurido, sedação, náusea e vômitos. No grupo CLON/ISO houve diminuição significativa da pressão arterial média com relação ao grupo CLON/HIPER nos momentos 15, 30 e 45 minutos (p < 0,05). CONCLUSÕES: Nas condições estudadas, a adição de clonidina em baixa dose (30 ¼g), associada ao sufentanil, determinou maior ocorrência de hipotensão quando administrada com soluções isobáricas de anestésico local. Com relação aos demais efeitos colaterais, as soluções hiperbáricas e isobáricas comportam-se de maneira semelhante.JUSTIFICATIVA Y OBJETIVOS: La adición de la clonidina subaracnoidea (±-agonista), prolonga la acción analgésica de la combinación sufentanil y bupivacaína isobárica en analgesia combinada para el trabajo de parto ¹. El objetivo de este estudio fue comparar la calidad de analgesia y la prevalencia de los efectos colaterales, después de la adición de clonidina subaracnoidea a la solución anestésica en gestantes durante el parto. MÉTODO: Después de la aprobación de la Comisión de Ética, 22 gestantes en trabajo de parto recibieron aleatoriamente en el espacio subaracnoideo 2,5 mg de bupivacaína hiperbárica 0,5% (grupo CLON/HIPER; n = 11) o 2,5 mg de bupivacaína isobárica 0,5% (grupo CLON/ISO; n = 11) en asociación con el sufentanil 2,5 µg y la clonidina 30 µg. El dolor evaluado por la Escala Analógica Visual, la frecuencia cardíaca y la presión arterial promedio, fueron estudiados a cada 5 minutos en los primeros 15 minutos y a continuación, a cada 15 minutos hasta el nacimiento. Fue evaluada la prevalencia de efectos colaterales (náusea, vómito, prurito y sedación). El estudio fue terminado en el momento en que se hizo necesaria la complementación analgésica epidural (dolor > 3 cm) o al nacimiento. El análisis estadístico fue realizado a través de los tests t de Student, Chi-cuadrado, Fisher y ANOVA de dos vías para medidas repetidas, considerando como significativo p < 0,05. RESULTADOS: Los grupos CLON/HIPER y CLON/ISO fueron similares con relación a los datos antropométricos, duración de la analgesia (70,9 ± 32,9 vs. 85,4 ± 39,5), frecuencia cardíaca, incidencia de prurito, sedación, náusea y vómitos. En el grupo CLON/ISO hubo una disminución significativa de la presión arterial promedio con relación al grupo CLON/HIPER en los momentos 15, 30, y 45 minutos (p < 0,05). CONCLUSIONES: En las condiciones estudiadas, la adición de clonidina en baja dosis (30 ¼g), asociada al sufentanil, determinó una mayor incidencia de hipotensión cuando se administró con soluciones isobáricas de anestésico local. Con relación a los demás efectos colaterales, las soluciones hiperbáricas e isobáricas se comportan de manera similar.BACKGROUND AND OBJECTIVES: The addition of subarachnoid clonidine (α-agonist) prolongs the analgesia produced by the combination of sufentanil and isobaric bupivacaine in combined labor analgesia¹. The objective of this study was to compare the quality of analgesia and the prevalence of side effects after the addition of subarachnoid clonidine to the anesthetic solution in labor analgesia. METHODS: After approval by the Ethics Commission, 22 pregnant women in labor were randomly assigned to the subarachnoid administration of either 2.5 mg of 0.5% hyperbaric bupivacaine (CLON/HYPER Group; n = 11) or 2.5 mg of 0.5% isobaric bupivacaine (CLON/ISO Group; n = 11) associated with 2.5 µg of sufentanil and 30 µg of clonidine. Pain, evaluated by the Visual Analogue Scale, heart rate, and mean arterial pressure were assessed every 5 minutes during the first 15 minutes, and then every 15 minutes afterwards until delivery. The prevalence of side effects (nausea, vomiting, pruritus, and sedation) was evaluated. The study was terminated whenever the patient needed supplemental epidural analgesia (pain > 3) or upon delivery of the fetus. The Student t test, Chi-square test, Fisher exact test, and two-way ANOVA for repeated measurements were used in the statistical analysis and a p < 0.05 was considered significant. RESULTS: Anthropometric data, duration of analgesia (70.9 ± 32.9 vs. 85.4 ± 39.5), heart rate, and the incidence of pruritus, sedation, nausea, and vomiting were similar in both groups. Mean arterial pressure was significantly lower in the CLON/ISO Group than in the CLON/HYPER Group at 15, 30, and 45 minutes (p < 0.05). CONCLUSIONS: Under the conditions of the present study, the association of a small dose of clonidine (30 µg) with sufentanil caused a higher incidence of hypotension when the isobaric solution of the local anesthetic was used. For all other side effects, both hyperbaric and isobaric solutions showed similar behavior.

Multi-stability refers to the phenomenon of perception stochastically switching between possible interpretations of an unchanging stimulus. Despite considerable variability, individuals show stable idiosyncratic patterns of switching between alternative perceptions in the auditory streaming paradigm. We explored correlates of the individual switching patterns with executive functions, personality traits, and creativity. The main dimensions on which individual switching patterns differed from each other were identified using multidimensional scaling. Individuals with high scores on the dimension explaining the largest portion of the inter-individual variance switched more often between the alternative perceptions than those with low scores. They also perceived the most unusual interpretation more often, and experienced all perceptual alternatives with a shorter delay from stimulus onset. The ego-resiliency personality trait, which reflects a tendency for adaptive flexibility and experience seeking, was significantly positively related to this dimension. Taking these results together we suggest that this dimension may reflect the individual's tendency for exploring the auditory environment. Executive functions were significantly related to some of the variables describing global properties of the switching patterns, such as the average number of switches. Thus individual patterns of perceptual switching in the auditory streaming paradigm are related to some personality traits and executive functions.